SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) INTRODUCTION

Transcription

1 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Facility Name: Shoosmith Sanitary Landfill SWP #: 587 Type of Application: Review Type: Prepared by: Reviewers: Documents Reviewed: Attachments: 1. Waste Material Management and Disposal Approval Application, prepared by SCS Engineers, submitted July 28, 2015, and finalized August 31, Part B Application for Quarry Cell 28, prepared by SCS Engineers, dated October 21, 2011 Technical Golder Associates Inc. (Golder) Mike Williams, C.P.G., Golder Associates Inc. Mark McClain, P.E., Golder Associates Inc. Jeff Rusch, P.E., Golder Associates Inc. Terri Phillips, P.G., Golder Associates Inc. 1. SCS s Response to Golder s Comments on Solid Waste Permit Technical Review, dated August 23, SCS s Follow-up Response to Golder s Comments on Solid Waste Permit Technical Review, dated August 28, 2015, with attachments Attachment 1: SCS s Follow-up Response to Golder s Comments on Solid Waste Permit Technical Review, dated August 28, 2015, with attachments Attachment 2: SCS s Response to Golder s Comments on Solid Waste Permit Technical Review, dated August 23, 2015 INTRODUCTION This Technical Review Memorandum outlines Golder s observations, comments, and concerns on the design, operating conditions, and associated permit documents for Cell 28 (the Quarry Cell) at the Shoosmith Sanitary Landfill in Chesterfield County, Virginia. The review focused on technical aspects of the design and design/operating condition for consistency with Chesterfield County ordinances, the facility-specific Conditional Use Permit, Virginia Solid Waste Management Regulations (VSWMR), and industry standards with a primary goal of understanding the impacts if any to human health and the environment that could be associated with the proposed design under normal operating conditions and/or in a failure mode. This Memorandum addresses Shoosmith Bros. Inc. s responses dated August 23, 2015, and August 28, 2015, (via SCS Engineers) to the initial Technical Review dated August 12, 2015 (copy attached, along with SCS s two response documents). Golder believes that the proposed Municipal Solid Waste (MSW) landfill design is atypical when compared to the vast majority of MSW landfills that are currently being operated in the United States (i.e., fractured rock quarry, significant gradient control systems, and depth of fill) and there are several technical constraints, physical concerns, and unknown operating conditions that could result in one system or cascading system failures that would be very difficult, if not infeasible, to repair/recover from. These potential failures could result in significant long-term impacts to human health and the environment. Therefore, Golder recommended that additional evaluations above and beyond that which Golder Associates Inc., Reference No Page 1 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

2 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) are typically performed for at-grade/above water-table MSW landfills be completed to ensure that the design will operate to the required performance standards, with appropriate fail-safe mechanisms and/or redundancies. As a point of clarification, SCS states that both the County and DEQ approved the siting and operation for the Quarry Cell in However, it is our understanding that Shoosmith only applied for siting approval for the Quarry Cell pursuant to County Code Chapter 11 Article VII, and only applied for Part A (siting) approval for the Quarry Cell pursuant to the VSWMR. The current County approval application is for operations pursuant to Chapter 11 Article VIII, and the current DEQ permit application for Part B (design and operation) of the Quarry Cell. Golder s original technical comments regarding the operational integrity of the proposed Cell 28 liner, leachate collection, landfill gas collection, and underdrain dewatering systems based on technical constraints, physical concerns, and unknown operating conditions that will likely be encountered during construction, operation, and in post-closure care, are duplicated below in italics. SCS s responses are attached in their entirety. Golder s responses to SCS s responses are provided below, and state whether the issue or concern has been adequately addressed, whether Golder requests additional information or consideration, and/or whether Golder has recommendations for the County s consideration (which are underlined for convenience). TECHNICAL REVIEW - GENERAL COMMENTS 1. The overall concept for the landfill requires that three active systems (groundwater control, leachate collection, and gas collection) be operational for significant periods of time and with minimum down-time to prevent non-compliance with various Virginia regulatory requirements and/or engineering failure of key components of the landfill systems. Also many of the landfill components are unique due to geometry of the side walls, the inflow of groundwater and overall depth. Because of the uniqueness of the design features, these designs need to be developed in sufficient detail so that adequate potential failure analysis can be performed. Of particular concern is the gas collection system as this system design is not as well developed as the groundwater control or leachate collection system. While this is typical for landfills installing vertical wells after final grades are reached, this gas system must be fully vetted and designed as a part of the permit application because its installation will begin early in the development of Cell 28 with the placement of horizontal collectors. See SCS s response, attached. Golder s Response: While the regulations and requirements that govern the Quarry Cell are the same as standard landfills, we disagree with the statement that this design is not atypical. There are many landfills that share some of the characteristics (e.g., excavated into bedrock), yet very few that combine all the characteristics (overall depth, in bedrock, steep side-slopes, overall geometry, dependence initially on a deep active groundwater dewatering system). Our comments are not meant to be construed that these characteristics cannot be accounted for in the design, but rather that many of the design elements require more engineering than is typical, and the consequences of failure of these systems will be difficult to remedy because of depth, geometry, and accessibility. Hence, our comments are directed toward making sure critical design issues have been addressed and contingency plans have been formulated in the case of failure. * * * * The comments below are provided given the critical and unique nature of some of the design features to help provide better confidence that critical design issues have been identified and addressed. These comments do not indicate that the existing design will fail, unless specifically Golder Associates Inc., Reference No Page 2 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

3 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) stated as our opinion for a specific component. Unless specifically noted, the request is being made for further analysis to evaluate potential failure. A) Make sure all calculations are checked and reviewed. Several critical calculations from subcontractors have not been checked (example: Landmark vertical wall design). Additionally, several inconsistencies were identified within and between design calculations. For example, several unit weights of MSW were utilized throughout the calculations. In addition, the equivalence demonstration of the proposed liner systems do not correctly reflect the proposed liner system components presented in the Permit Drawings and Design Report. It is acknowledged that while these inconsistencies may not affect the overall conclusions of the design calculations, the design assumptions should be consistent throughout the application. See SCS s response, attached. Golder s Response: Response is acceptable. Please note that it is standard practice to have final initialed versions of the calculations contained in the Permit Application in case questions arise later for those performing, checking, and reviewing the calculations. * * * * B) The design should include reasonable measures to reduce the amount of water reaching the groundwater control system during the early stages of filling. Specifically, this would include intercepting surface water run-on to the maximum extent possible before it reaches the groundwater control system. This would lengthen the amount of time that the groundwater pumping system could be down prior to causing the unacceptable buildup of hydraulic pressures under the bottom liner. See SCS s response, attached. Golder s Response: Response is acceptable. * * * * C) Provide additional details and technical support on the gas collection design, particularly the following: a. The connection of horizontal collectors to vertical risers and potential failure of these connections due to differential movement of risers and laterals. See SCS s response, attached. Golder s Response: Response is acceptable. Please note that the basis for this comment is that we believe there is a high probability of failure for the system components identified in our comments based upon the design shown in the Permit Application. A primary factor is the total depth of waste and the difficulty in reaching deep portions of the landfill to remedy failed system components. Because of this complicating factor, we recommend redundancies to the system components as a part of the system design (many were discussed in the response to our comment), as it will be technically difficult and expensive to remedy component failures as the depth of waste increases. We recommend the redundancies be added to the permit application following Chesterfiedl County review and that they be made an enforceable condition of the permit. * * * * Golder Associates Inc., Reference No Page 3 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

4 See SCS s response, attached. Golder s Response: Response is acceptable. See SCS s response, attached. Golder s Response: Response is acceptable. SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) b. Provide technical support for using Standard Dimension Ratio (SDR) 17 High Density Polyethylene (HDPE) for lateral collectors. SDR-11 is recommended in trenches for ground water and leachate collection and these pipes will be in trenches on a firm base. The trench recommended for the gas collectors is likely to be less effective in providing support since it will be cut into waste, which will not provide for a firm backfill around the pipe. The use of tire shreds is not advised for backfill since they will be compressible. * * * * * * * * c. The potential for failure of individual horizontal collectors due to condensate accumulation, pipe crushing, higher temperatures, and differential settlement. What measures can be taken to detect failed collection laterals and remedy (provide gas collection to these area) them. * * * * D) The Design Report discusses a third option for the VZSS and the locations of the Mechanically Stabilized Earthen (MSE) wall are shown on the Permit Drawings; however, design details for the MSE wall and its compatibility and connection with the proposed liner systems are not provided in the Permit Drawings. See SCS s response, attached. * * * * Golder s Response: Although we recommended that additional details of the MSE wall design be incorporated into the permit application consistent with the information currently provided on the other VLSS options, we acknowledge that the permit application was determined to be technically adequate by the DEQ and defer to DEQ for required content. It is noted that Golder was unable to review the referenced examples of the permit-level design details for the existing MSE berm at the facility because the documents were not provided for review. County review of these documents as part of the Cell 28 review is recommended due to the interaction between the proposed Cell 28 liner system and the MSE wall. * * * * E) Provide details for how the recovery of groundwater and leachate from these systems will be achieved for the different waste stages prior to waste reaching the rim of the quarry. See SCS s response, attached. Golder s Response: Response is acceptable. Golder Associates Inc., Reference No Page 4 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

5 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) * * * * F) The active leachate system will be depended upon to remove leachate from multiple sources for extended periods of time, some of which are not typical for MSW landfills. These include: a. Condensate from the gas system collector laterals; b. Inflow of groundwater through leaks in the liner system; c. Leachate from the recirculation system; d. Infiltration through the cover, particularly the steeper 3H:1V slopes that do not contain a flexible membrane liner; and e. Normal leachate generation from precipitation during construction and waste filling. See SCS s response, attached. Because of this, leachate quantities could actually increase over time during operations and the system may have to pump well beyond the typical 30-year post-closure time frame. Given the critical nature of this system, the components of the system should be viewed as requiring extended life with appropriate design considerations included as needed to demonstrate the systems will function as desired for the life of the landfill. This also illustrates the importance of including construction of this system in the Construction Quality Assurance (CQA) Plan. Golder s Response: Response is acceptable. Please note that the basis for this comment is not that the flows cannot be accounted for in the design; we accept that SCS has accounted for the flows from each of these sources. The purpose of the comment, similar to the comments on the landfill gas system, is that each of these sources contributes to the flow, and the active system must continue to operate until these flows abate, which could last beyond 30 years post-closure. Because of the depth, geometry, and setting of the Quarry Cell, problems with the leachate system will be difficult to remedy. Therefore, we recommend redundant features (some have been mentioned by SCS in their response) be built into the original design in case failures occur. Golder recommends that the County review these updated designs and that they be included in the permit as enforceable permit conditions. Although we agree that the 3H to 1V slopes in the cover will encourage runoff and minimize infiltration, we do not believe that low permeability soils in covers without a geomembrane overlying them are effective in reducing infiltration into the landfill. This is due primarily to differential settlement of the soil, which induces tension cracks and increases permeability well above the permeability achieved during construction. Therefore, Golder recommends that a flexible membrane liner be included in the cap design for Cell 28 regardless of slope conditions to provide for long-term odor management (in the event of a temporary gas collection and control system failure), and to prevent, to the extent practicable, the inadvertent introduction of atmospheric oxygen to the waste mass by the active gas collection and control system when properly operating. Golder recommends that the County review these updated designs and that they be included in the permit as enforceable permit conditions. We have reviewed the new Liquids Management Plan provided by SCS, which includes leachate management. This plan discusses a leachate pre-treatment system; it is not clear whether this system currently exists or is a planned component of the future leachate management system. We request clarification from SCS. It is also unclear why the leachate pumps are designed to meet the average annual leachate flow [54 gallons per minute (gpm)], while the leachate collection pipes were designed to handle the peak daily flows of 370 gpm. We request the rationale for these design criteria. In addition, this plan includes a calculation of required leachate storage capacity (830,000 gallons) for the Quarry Cell to meet the 7-day storage requirement in the VSWMR (9VAC B). The calculation is based on the assumption that leachate recirculation would be occurring, presumably to reduce the required storage capacity. It is unclear how this storage capacity requirement can be met by the proposed optional leachate tank farm since discharge to the County sewer will be limited to a maximum of 83 gpm. Golder requests clarification from SCS. Additionally, since existing on-site storage is limited (absent due to County sewer connection) and since the County sewer system discharge is limited to a maximum of Golder Associates Inc., Reference No Page 5 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

6 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) 83 gallons per minute, Golder recommends that the County require Shoosmith to install on-site leachate storage capacity equal to the maximum 7-day flow in excess of the permitted discharge limit for the entire Facility based on a worst-case scenario for leachate generation following a potential Cell 28 liner failure or the discovery of impacted gradient control water, and that this design be incorporated into the Facility s permit as an enforceable condition. REVIEW COMMENTS The applicable design/operating requirements are outlined below. Each requirement is followed by a summary of the type of information required and the applicable technical standards that must be met. In the Comments section following each requirement, we have summarized areas of concern, followed by our response to SCS s responses to each of those comments and concerns. The reader is referred to the Virginia Solid Waste Management Regulations (VSWMR; 9VAC20-81 et seq.), the CUP (CUP #97SN0206, May 28, 1997) issued by Chesterfield County, applicable County Code sections (Chapter 11, Articles V, VII, and VIII), and DEQ correspondence as referenced for a full description of each standard. Golder s initial technical review and SCS s responses are attached for reference. The review focused on sections of the application describing the design, construction and operation, monitoring, closure and post-closure care of the facility. Recommendations are suggested to ensure that a particular section of the application is technically adequate. The following terms are used to describe the reviewers comments regarding completeness and technical adequacy determinations: Complete Incomplete Adequate Area of Concern This term indicates that the application contains a comprehensive and accurate discussion of the particular subject. Adequate information is provided. This term indicates that the application does not contain a comprehensive and accurate discussion of the particular subject. Additional information is requested. This term indicates that the information provided demonstrates that the facility will be able to comply with the applicable technical standard(s). This term indicates that the information provided fails to demonstrate that the facility will be able to comply with the applicable technical standard(s). Additional or revised information is requested. 1.0 CONDITIONAL USE PERMIT REVIEW 1.1 Proffered Condition No. 13 The phrasing in the draft permit (Module II) is inconsistent with the CUP phrasing. Golder recommends that the phrasing in the draft module be standardized to match that in the CUP. Specifically, draft Permit Condition II.A.1 should be modified to indicate that the facility operator will restrict waste delivery operations between the hours of 12:00 AM and 06:00 AM to only trucks owned and operated by Shoosmith Brothers, Inc. with no more than 12 trucks allowed during the 12:00 AM and 06:00 AM timeframe (i.e., number of trucks shall not exceed an average of two trucks per hour). See SCS s response, attached. Golder s Response: Response is acceptable. * * * * 1.2 Proffered Condition No. 14 The phrasing in the draft permit (Module II) is inconsistent with the CUP phrasing. Golder recommends that the phrasing in the draft module be standardized to match that in the CUP. Specifically, draft Permit Golder Associates Inc., Reference No Page 6 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

7 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Condition II.B.2 should be modified to indicate that the facility operator will not accept stock farm animal carcasses for disposal in the waste management area. See SCS s response, attached. Golder s Response: Response is acceptable. * * * * 1.3 Proffered Condition No. 25 The condition required the facility owner to file restrictive covenants in a form or forms acceptable to the County Attorney that satisfy the description as stated in Exhibit C of the CUP. The May 20, 1999, DEQ approval letter for Permit No. 587 is labeled as Final Permit Number 587. At this time, it is unclear whether the restrictive covenants in Exhibit C of the CUP have been filed to the satisfaction of the County Attorney. See SCS s August 28, 2015, response, attached. Golder s Response: Response is acceptable. SCS has indicated that Shoosmith Bros. Inc. will file the required restrictive covenants following DEQ s approval of the Cell 28 permit amendment. * * * * 2.0 PART A APPROVAL CONDITIONS 2.1 Condition 6, March 2, 1999, Part A Approval Letter Condition 6 required the facility operator to submit a minimum of 3 years of monthly data for metered pumping rates and volumes from within the quarry, along with monthly precipitation and other hydrological data for the quarry to assist with the design of the Cell 28 groundwater control system. In the notes to the January 27, 1999, Board of Supervisors meeting (Item 16B), a Mr. Hale is noted as stating during dry weather, there are 28,000 gallons per day of water being pumped out of the quarry. Golder reviewed the pumping information submitted by Shoosmith Brothers, Inc. to the DEQ to meet Condition 6 (see submittal letter from Joyce Engineering dated October 29, 2009). These pumping data covered the years of 2006, 2007, 2008, and the first 3 months of A summary of the pumping information (gallons per day average for the above timeframes) is presented below: Gallons per day Year (yearly total divided by number of days) , , , ,500 As presented, the average pumping per-day rate for the 2006 to 2009 timeframe is significantly higher than the volume reported in From the report, it is not clear if this water was pumped out of the quarry as appears to be the intent of the condition, and it is not clear whether these volumes are commingled stormwater and groundwater dewatering, or a combination of stormwater, groundwater, process water, and surface water impoundment leakage. Additionally, the report does not address the source of the change observed in the average daily pumping rates between 2006 and 2009, or 1999 for that matter. In summary, it is unclear if the gradient control dewatering system for Cell 28 has been adequately designed to handle the flows that appear to require management. Golder recommends that the source of the volume variations be further evaluated to ensure that the dewatering system can handle the expected flow, with any expected variance, so as to protect the liner from hydrostatic uplift. Golder Associates Inc., Reference No Page 7 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

8 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) See SCS s August 28, 2015, response (new Liquids Management Plan), attached. Golder s Response: Response is acceptable, although it is still not clear how much of the documented flow is from the groundwater inflow, and thus, questions regarding the expected quality and volume of the flow remain unanswered. Since the flow is expected to impact the amount of on-site leachate storage capacity that is required, Golder recommends that Shoosmith Bros. Inc. complete this determination in support of the onsite leachate storage evaluation. 3.0 ENGINEERING DESIGN REVIEW * * * * Landfill Capacity 9VAC A Comments... Complete Incomplete Adequate Area of Concern 1. Adequately addressed in the permit application Vehicular and Public Access Controls 9VAC B Comments... Complete Incomplete Adequate Area of Concern 1. Unclear what type of safety measures/access controls currently exist or are proposed along the top of the quarry high wall. See SCS s response, attached. Golder s Response: The response references safety and access protocols discussed in the Operations Manual for the Quarry Waste Disposal Unit. However, this document was not provided for review. Golder recommends that the County require that some type of high wall safety measure, such as a fence with posted warning signs be incorporated into the permit application and permit, including safety measures for the access road into the Quarry Cell. * * * * Access Roads 9VAC C Comments... Complete Incomplete Adequate Area of Concern 1. No access road detail provided in the Permit Drawings. See SCS s response, attached. Golder Associates Inc., Reference No Page 8 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

9 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Golder s Response: The response is acceptable. * * * * Surface Water Runoff 9VAC H Comments... Complete Incomplete Adequate Area of Concern 1. The description of the run-on control system is inadequate to evaluate whether the proposed runon system is sufficient in mitigating run-on to the quarry. In addition the Gradient Control Plan seems to indicate that the gradient control system was designed for groundwater infiltration and precipitation over the quarry area, but does not account for run-on from surrounding drainage areas. See SCS s response, attached. Golder s Response: The response adequately addresses the review comment. However, Golder recommends that the County require the following content of the response be incorporated into the permit application and permit: The existing berm that is positioned at the rim of the quarry pit will remain in place upon termination of commercial quarry operations, and be improved or enhanced prior to liner system construction activities where appropriate, to divert stormwater from the areas surrounding the quarry pit into conveyance features on the rim. It is noted that the response references Sheets of the Permit Design Drawings, which were not provided for review. * * * * Liner Systems 9VAC J Comments... Complete Incomplete Adequate Area of Concern 1. The alternative liner system equivalence demonstration calculations presented in Appendix G of the Design Report do not correctly model the proposed alternative bottom liner system presented in the Design Report and shown on the Permit Drawings. Additionally, the references for the assumed hydraulic conductivities of the concrete and synthetic sheet piling VLSS materials are unclear. For example, does the assumed hydraulic conductivity of concrete assume any degree of cracking/degradation? By inspection of the proposed VLSS systems, the concrete structural members will consist of pre-cast or cast-in-place panels installed between steel soldier piles or will consist of vinyl sheet piling. However, the Design Report does not address whether the concrete-i beam interface or the sheet piling interlocking will be adequately water sealed (nor is this discussed in the CQA Plan). Therefore, the equivalence demonstration of the alternate liner systems should demonstrate performance at the locations of these construction joints. See SCS s response, attached. Golder Associates Inc., Reference No Page 9 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

10 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Golder s Response: The response adequately addresses the review comment. However, Golder recommends that the County require that the revised calculations and the requirement that the VLSS joints be water-sealed be incorporated into the permit application and permit as an enforceable condition. * * * * 2. Liner equivalence demonstration calculations are not presented for the sidewall bench alternative liner options. It is unclear why the benches are not proposed to have a Subtitle D or double-liner system consistent with the proposed bottom liners. Golder recommends that the benches and sidewalls be equipped with Subtitle D or equivalent Geosynthetic Clay Liner (GCL)/HDPE type liner system. See SCS s response, attached. Golder s Response: The response is acceptable from a technical leachate collection standpoint. However, if Shoosmith intends to terminate the gradient control system operation at some point in the future, a single liner system with 1E-05 centimeter per second compacted soils is not an acceptable option since at that time, the liner systems purpose will be two folds: 1. Contain leachate; and 2. Keep groundwater out. Golder Therefore, unless Shoosmith intends to commit to operating the gradient control system indefinitely, the alternative design should be removed from the permit documents and the draft permit module. Golder recommends that County staff obtain specific clarification on Shoosmith s intention with regards to this item and that the County request the applicable change to the permit in written comments to the DEQ. Golder recommends that Shoosmith also evaluate the sideslope liner systems with consisderation to leakage from outside hydrostatic pressure following termination of the gradient control system if termination of the gradient control system operation is the final decision and that the updated design be incorporated into the permit as an enforceable condition. * * * * 3. The Design Report does not address the build-up of hydrostatic forces outside of the liner system causing deflection and potential failure of the liner system inward in the event of gradient control failure. Similar to comment #1, the sealant of construction joints in the liner system is not addressed. See SCS s response, attached. Golder s Response: The response adequately addresses the review comment. However, Golder recommends that the County require that water-sealing the VLSS joints be incorporated into the permit application and permit as an enforceable condition. * * * * 4. The structural calculations for the vertical support system appear to assume fixity of the vertical member at the base of each vertical wall. However, no design or constructability details were provided on how the vertical structural members will be installed/fixed (i.e., concrete foundation sizing and structural requirements, sheet pile embedment depth). See SCS s response, attached. Golder s Response: Golder recommends that the constructability of the VLSS system options be discussed in the permit application and that basic design information for the VLSS anchor system be incorporated into the permit. Golder Associates Inc., Reference No Page 10 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

11 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) * * * * 5. There appear to be several inconsistencies in the structural calculations for the VLSS wall (e.g., is deflection calculated for the full 40-ft wall or just the 20-ft section above tie-back?) The calculation computes deflection for the 40-ft wall based on the loading of 5-ft lifts of flowable fill, but only multiplies the deflection x4 for the full wall. Additionally, it appears that the structural calculations do not verify maximum bending moment in the sheet pile wall. See SCS s response, attached. Golder s Response: It is unclear why the referenced structural calculations are included in the permit application while other constructability and design issues are considered by the applicant as not appropriate for a permit-level application. Golder believes that all calculations as may be required to demonstrate that the landfill components can be constructed in a manner that will perform to the design specifications should be included in the permit and/or permit supporting documents since these design elements and materials will in part determine Shoosmith s ability to safely operate Cell 28 in accordance with the requirements of Article VIII, Section Golder recognizes that since the quarry grades are not final, the Cell 28 design cannot be finalized without certain assumptions; however, Golder believes that the assumptions and supporting calculations should sufficiently account for the range of construction scenarios likely to be encountered during preparation of the construction documents, since additional design review input by the DEQ is unlikely to occur once the DEQ solid waste permit has been issued. Therefore, Golder recommends that the County require Shoosmith to submit construction drawings and specifications to the County for review and comment a minimum of 90 days prior to each proposed phase of construction and that this condition be incorporated into the Facility s solid waste permit as an enforceable condition. * * * * 6. Provide details for how the groundwater control and leachate collection systems will be constructed, accessed, and operated during the early stages of landfilling prior to full completion of the riser pipes. See SCS s response, attached. Golder s Response: The response adequately addresses the review comment. Golder recommends that the County require the language in the response be incorporated into the permit application and permit (as offered by the applicant), as these details for constructing and operating the systems will be applicable for many years until the construction of these systems reaches the quarry rim. * * * * 7. The leachate/gradient control side slope riser pipe compound detail indicates that the riser compound will penetrate the vertical liner systems. However, no details have been provided as to how those penetrations will be constructed or sealed to ensure liner integrity. See SCS s August 28, 2015, response, attached. Golder s Response: Although we acknowledge the note added to Sheet 77 of the design drawings ( Side slope riser pipes do not penetrate the vertical liner system ), it remains unclear in the details how the sideslope riser pipe compound will not penetrate the VLSS. It is unclear where the VLSS is situated and how the bottom liner transitions to the VLSS liner in the referenced details 3 and 7 on Sheet 76. Additionally, it is unclear whether the VLSS is situated in the foreground of detail 2 on Sheet 77. To ensure the proper construction of this critical component of the Quarry Cell design, which may not occur for several years, Golder Associates Inc., Reference No Page 11 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

12 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Golder recommends that the design drawings and details be clarified so as to avoid any future confusion during the development of construction-level drawings. * * * * 8. No down drag-tensile capacity evaluation of the superficial geotextile and geocomposite drainage layer was performed. While the geotextile is a superficial component of the liner system, the geocomposite drainage layer is critical to conveying leachate flows from the sidewall benches to the leachate collection system. See SCS s response, attached. Golder s Response: The response adequately addresses the review comment. Golder recommends the County require that the nonwoven geotextile be identified in the permit application as sacrificial, and therefore not part of the proposed liner system. * * * * 9. The Design Report calls for an 18-inch fluff layer to be constructed adjacent to the vertical liner system. However, the constructability of this layer was not addressed. See SCS s response, attached. Golder s Response: The response adequately addresses the review comment. However, Golder recommends that the County require that the content be incorporated into the permit application and permit as an enforceable conditon. * * * * Final Grades 9VAC O Comments... Complete Incomplete Adequate Area of Concern 1. The slope stability calculations reference 3:1 final side slopes. However, these side slopes are not identified and therefore were not verified on the Permit Drawings. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * Approved Plans 9VAC P Comments... Complete Incomplete Adequate Area of Concern Golder Associates Inc., Reference No Page 12 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

13 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) 1. The proposed design provides the Owner significant flexibility in the construction of the liner systems, based on site-specific conditions and the base design is based on an assumed quarry completion plan. In addition, there are several construction level reports and documents referenced throughout the Permit Application. Conditional approval of this permit application should require regulatory review and approval of all construction documents/plans in advance of construction. See SCS s response, attached. Golder s Response: The comment was not addressed. We are recommending that construction packages be approved prior to construction. There are critical environmental aspects of the permit-level design that are not addressed and have been left to construction-level design. Golder agrees that it is appropriate to leave many of these details until the construction-level design. However, many aspects of the design are unique to this project. An example is how leachate will be conveyed up the quarry walls during early waste filling and prior to complete construction of the riser system. Therefore, Golder recommends that the County request Shoosmith to submit construction drawings and specifications to the County for review and comment a minimum of 90 days prior to each proposed phase of construction and that this condition be incorporated into the Facility s solid waste permit as an enforceable condition. * * * * 2. More details should be provided on the construction of the gas collection system since it will be installed as the landfill is filled. Please provide details of the vertical Landfill Gas (LFG) collectors placed around the perimeter of the landfill and the access vault shown on drawing 68. Show connection details for the vertical collectors and LFG horizontal collector and demonstrate how these connections will be maintained with differential movement of the vertical collectors and the horizontal collectors. How will the vertical LFG collectors be supported? See SCS s response, attached. Golder s Response: The response is acceptable. We are agreement that these details can be provided as a part of the Design Plan for the DEQ Division of Air Quality. As stated previously, we recommend multiple redundancies in the design of the system given the depths of waste and high likelihood of failure of individual components. * * * * 3. Provide calculations for the HDPE SDR 17 horizontal laterals that show that they can withstand the overburden pressures from the waste and remain functional in the gas collection system under the most elevated operating temperature that is realistically expected (e.g., 180 degrees Fahrenheit is commonly observed). See SCS s response, attached. Golder s Response: The response is acceptable. If laterals are ineffective, we are concerned that there will be limits to how deep vertical wells can be drilled. Depending upon the point in time (i.e., depth of waste) that the laterals are found to be ineffective, vertical wells may have limited effectiveness. How deep does SCS believe that vertical wells can be realistically drilled and installed? Golder recommends that Shoosmith specifically address this comment in the facility s Landfill Gas Management Plan based on Shoosmith s experience with drilling and constructing landfill gas wells, and that the landfill gas collection and control systems, including the redundancy and contingency items, account for this maximum depth. * * * * Golder Associates Inc., Reference No Page 13 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

14 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) 4. It is not clear why a detail for a vertical LFG collection well is provided if vertical wells are not deemed appropriate for the LFG system. Please provide information about how the vertical wells will be integrated with the system of lateral collectors. The DEQ draft permit modules indicate that the wells will be installed to 75% of the waste mass thickness. This requirement is inconsistent with the permit drawings and design documents. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * CQA Plan 9VAC Q Comments... Complete Incomplete Adequate Area of Concern 1. The Technical Specifications and CQA Plan should provide detailed construction specifications, material requirements, and construction testing requirements for all materials and components proposed as part of the design, including all systems, liners, and final cover. This includes HDPE pipe, structural materials for the VLSS, backfill materials behind the VLSS system including earthen backfill, flowable fill, grout, and VLSS joint sealant materials, and final cover materials. While it is acknowledged that these technical specifications may not be required for permit level approval, the Technical Specifications and CQA Plan appear to provide comprehensive material specifications and requirements for geosynthetic liner materials, but do not provide any substantive specifications or requirements for pipe or structural members which are critical components of the design and must be adequately designed for system performance. See SCS s response, attached. Golder s Response: This comment was directed, in particular, at components of the VLSS that will be critical to the stability and performance of the vertical liner system. Golder recommends that the final specifications, which are to be provided in the construction-level design, be provided to Chesterfield County for review and comment and to the DEQ for review and approval, and that this condition be incorporated into the permit as an enforceable condition. This will allow review of the final design and it will allow the CQA Plan to monitor compliance with the specifications. Additionally, Golder recommends that the County request additional specifications for the VLSS materials be incorporated into the permit application and permit. The applicant s response that specifications will be finalized depending on which VLSS option is selected is not consistent with the request for approval of several VLSS design options without additional detail/specification. * * * * Final Cover 9VAC D Comments... Complete Incomplete Adequate Area of Concern Golder Associates Inc., Reference No Page 14 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

15 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) 1. The Design Report does not address the proposed final cover system, specifically the equivalence and performance of the separate final cover sections proposed for the landfill crown slopes and side slopes relative to compliance with regulation. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * 4.0 ENVIRONMENTAL MONITORING PROGRAMS 4.1 VSWMR Groundwater Monitoring Program Groundwater Monitoring Program 9VAC Complete Incomplete Adequate Area of Concern Must install, operate, and maintain a groundwater monitoring system that is capable of determining the landfill s impact on groundwater quality in the uppermost aquifer at the disposal unit boundary during the active life and post-closure care period of the landfill. Comments According to the Groundwater Monitoring Plan (GMP) Once a sufficient mass of waste is in place to balance the upward pressure of the groundwater system on the landfill liner, the pumping of the gradient control system can be stopped. At least 1 year prior to turning off the pumping system, a proposed monitoring plan will be submitted to DEQ to address any changes to the inward gradient and the need to install additional perimeter downgradient wells. Golder recommends that the GMP address both current and future conditions. See SCS s August 28, 2015, response, attached. Golder s Response: SCS provided a drawing with the projected potentiometric surface after the gradient control system has been shut down and the aquifer has reached equilibrium. It is unclear why shutting down the gradient control system would lower the potentiometric surface of the aquifer outside of the Quarry Cell by 20 to 30 feet in some areas. No text revisions or discussion were provided. Golder recommends the County request clarification on the potentiometric surface elevation observation noted above and that a long-term groundwater monitoring plan be developed to adequately monitor the hydrogeologic site conditions during the required 30-year minimum post-closure care period, as well as the operating life of the Quarry Cell. * * * * Groundwater Monitoring System 9VAC A.3 Complete Incomplete Adequate Area of Concern Golder Associates Inc., Reference No Page 15 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

16 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Must install a groundwater monitoring system capable of yielding samples sufficient to represent background groundwater quality and groundwater quality at the disposal unit boundary. Must have at least one upgradient and at least three downgradient groundwater monitoring wells, with adequate lateral spacing based on site-specific information. Comments The Groundwater Monitoring Plan (GMP) does not match statements in the Landfill Gas (LFG) Management Plan with respect to the groundwater and LFG monitoring networks. The GMP says that P-203, P-206, and P-212 (among others) will be converted to groundwater monitoring wells. The LFG Plan says that P-202 through P-206, P-210, P-212, and P-116 will be converted to LFG probes. The Site Monitoring Plan drawings in the LFG Plan do not match either the LFG Plan text or the GMP. Golder recommends that the documents be reviewed and clarified/corrected as needed for consistency. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * 2. The groundwater monitoring network includes five gradient control sampling locations in the Quarry Cell (one at the bottom, four on the benches). The GMP states that if no volatile organic compounds (VOCs) are detected in the four bench samples at concentrations above the Quantitation Limit (QL), then future sampling will only be at the one bottom gradient control point. If the bottom gradient control sample has quantified VOC detections in the future, the other bench points may be sampled independently to try to determine the source area of the contamination. Golder recommends that this section of the GMP be revised to include provisions for four quarters of sampling and associated statistical analyses following in service placement of each gradient control system level with the detection limit (DL) used as the screening criterion so as to meet the highest level of environmental protection (contaminant identification) possible. The list of initial screening analytes should be expanded beyond VOCs to include metals, radio nuclei, biological oxygen demand (BOD), chemical oxygen demand (COD), ammonia, total nitrogen, and phosphorus. See SCS s August 28, 2015, response, attached. Golder s Response: The response is acceptable. Golder recommends that the County request Shoosmith to submit the new Liquids Management Plan to DEQ for inclusion in the Facility s solid waste permit as an enforceable document, given that components of the monitoring programs have been modified from those in the current permit application and draft permit (existing documents should be updated to reflect the conditions proposed in the new Liquids Management Plan. * * * * 3. The GMP states that if a VOC is detected in a gradient control sample at a quantified concentration, the operator has 30 days to complete verification re-sampling. If the re-sampling refutes the detection, the gradient control water may continue to be discharged. If the resampling confirms the detection, the operator has another 30 days to divert the discharge to the leachate system. Justification for this approach should be provided. In concept it would allow the discharge of solid waste constituents for as long as 60 days. Golder recommend consideration of immediate diversion once a VOC or other contaminant is detected (above the DL), pending the results of verification re-sampling. Golder Associates Inc., Reference No Page 16 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

17 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) See SCS s August 28, 2015, response, attached. Golder s Response: The response is acceptable. As above, Golder recommends that the County request Shoosmith to submit the new Liquids Management Plan to DEQ for inclusion in the Facility s solid waste permit as an enforceable document, given that components of the monitoring programs have been modified from those in the current permit application and draft permit (existing documents should be updated to reflect the conditions proposed in the new Liquids Management Plan. * * * * 4. No discussion is provided regarding the mining operation s dewatering program with respect to historical analytical monitoring data and Virginia Pollutant Discharge Elimination System (VPDES) permit limits. Golder recommends that a compilation and evaluation of available analytical data for the mining dewatering discharge be prepared to develop an understanding of existing groundwater quality as it relates to the gradient control monitoring points in GMP. See SCS s response, attached. Golder s Response: The response is acceptable. We understand the only available VPDES-related water quality data are for Total Suspended Solids, and are of limited value to this exercise. * * * * 5. The monitoring network includes underdrain samples (10 locations in the original landfill) for analysis of VOCs. Similar to the gradient control points, if a VOC is detected in an underdrain sample at a quantified concentration (above the QL), the operator has 30 days to complete verification re-sampling. If the re-sampling refutes the detection, the underdrain water may continue to be discharged. If the re-sampling confirms the detection, the operator has another 30 days to divert the discharge to the leachate system. Justification for this approach should be provided as it appears it would allow the discharge of solid waste constituents for as long as 60 days. Recommend consideration of immediate diversion once a VOC or other contaminant is detected (above the DL), pending the results of verification re-sampling. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * Groundwater Sampling & Analysis Requirements 9VAC A.4 Complete Incomplete Adequate Area of Concern Must include a quality assurance / quality control program. Must include provisions for establishing background concentrations. Must specify analytical, statistical, and data evaluation methods. Comments Adequately addressed. Golder Associates Inc., Reference No Page 17 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

18 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) * * * * Groundwater Protection Standards 9VAC A.6 Complete Incomplete Adequate Area of Concern Must identify the process for establishing Groundwater Protection Standards (GPS) once the facility is in the Assessment Monitoring Program. Comments According to the GMP, two different background databases will be established: one for saprolite/overburden (using upgradient well MW-115), and one for bedrock (using upgradient wells MW-114R and MW-203D). It is unclear which background will be used to establish the GPS for constituents for which background is above the regulatory limits. Recommend asking for clarification. See SCS s response, attached. Golder s Response: The comment was not addressed. We understand there will be two different sets of background values. Our question is which set will be used to establish any background-based Groundwater Protection Standards (GPS) or will there be two sets of background-based GPS? Golder recommends that the County request additional clarification on this issue and that it be addressed in the Facility s Groundwater Monitoring Plan. * * * * Monitoring for Sanitary Landfills 9VAC B Complete Incomplete Adequate Area of Concern Must specify monitoring frequency based on proximity to, and connection to, wetlands. Must describe requirements for Detection and Assessment Monitoring Programs, including sampling requirements, data evaluation and response, notifications, and groundwater monitoring plan. Comments The GMP states that the inward gradient design exempts the Quarry Cell from the quarterly groundwater monitoring frequency per House Bill 2471 until such time as the pumping stops, at which time the frequency will change from semi-annually to quarterly. No demonstration is provided to justify this assertion. Code of Virginia states, Groundwater monitoring shall be conducted at least quarterly by the owner or operator of any existing solid waste management landfill, accepting municipal solid waste, that was constructed on a wetland, has a potential hydrologic connection to such a wetland in the event of an escape of liquids from the facility, or is within a mile of such a wetland, unless the Director determines that less frequent monitoring is necessary Golder recommends that a formal demonstration be prepared at this Golder Associates Inc., Reference No Page 18 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

19 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) time since it appears a hydrologic connection may exist if contaminated water could be pumped to Swift Creek for discharge (even if only for 60 days as currently proposed). See SCS s response, attached. Golder s Response: The comment was not addressed. We believe the groundwater monitoring program is subject to the quarterly monitoring requirements of Code of Virginia , unless a successful demonstration is made to the DEQ regarding a lack of potential hydrologic connection to wetlands. We recommend the County request Shoosmith Bros. Inc. to perform quarterly groundwater monitoring pursuant to unless and until the DEQ approves the required demonstration. * * * * 2. The sampling frequency and parameters for the gradient control points are unclear; there are inconsistencies within the GMP text and Gradient Control Sampling Plan (App. III of the GMP). Recommend asking for clarification. See SCS s response, attached. Golder s Response: The comment was not addressed. Please clarify the sampling frequencies and parameters for the gradient control points, and ensure consistency among these documents with the new Liquids Management Plan. As discussed previously, we recommend the County request that Shoosmith Bros. Inc. make the Liquids Management Plan an enforceable document in the permit, as it modified some components of the GMP and Gradient Control Sampling Plan currently in the permit application and draft permit. * * * * Statistical Methods & Constituent Lists 9VAC D Complete Incomplete Adequate Area of Concern Must specify statistical methods and analytical parameters to be monitored. Comments The constituent lists cited in the GMP for the Detection and Assessment Monitoring Programs are the standard parameters for municipal solid waste landfills. However, the Quarry Cell has a history of mining, which uses blasting in its operation. Golder recommends that an evaluation of the blasting techniques used during the mining operation, including the chemical composition of the explosives introduced into the subsurface, and their potential effect on groundwater quality be performed. Consideration should be given to adding blasting-related constituents to the monitoring lists for both Detection and Assessment Monitoring, e.g., ammonia, biological oxygen demand (BOD), total petroleum hydrocarbons diesel range organics (TPH-DRO), and nitrates. Additionally, due to the presence of relatively freshly exposed granitic bedrock that is commonly affiliated with certain radioactive nuclei, Golder recommends that the potential for radioactive nuclei be evaluated and that appropriate parameters be included in the monitoring program. See SCS s August 28, 2015 response, attached. Golder s Response: Golder Associates Inc., Reference No Page 19 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

20 The response is acceptable. SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) * * * * Record Keeping & Reporting 9VAC E Complete Incomplete Adequate Area of Concern Must identify records to be maintained in the operating record. Must specify reporting requirements and timeframes. Comments Adequately addressed. * * * * 4.2 VSWMR Landfill Gas Monitoring Program Landfill Gas Monitoring Program 9VAC Complete Incomplete Adequate Area of Concern Must provide a landfill gas management plan to protect public health and the environment during landfill operations, closure, and post-closure. Must control landfill gas migration to comply with compliance and action limits at the facility boundary and in facility structures. Comments The Landfill Gas (LFG) Management Plan says that Shoosmith (not a 3 rd party consultant) will perform the LFG monitoring. On occasion a consultant may do the monitoring. Golder recommends that Shoosmith consider the use of a 3 rd party consultant with appropriate credentials to perform the monitoring and provide adequate documentation to ensure compliance. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * 2. According to the LFG Plan, once the Quarry Cell is operational, there will be insufficient LFG flare capacity in the event the LFG-to-energy operation shuts down. Suggest requiring the additional flare capacity as a condition of operating in the Quarry Cell. See SCS s response, attached. Golder s Response: The response is acceptable. Golder Associates Inc., Reference No Page 20 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

21 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) * * * * Landfill Gas Monitoring Network 9VAC B Complete Incomplete Adequate Area of Concern Must develop an adequate monitoring network based on site-specific conditions. Must monitor the landfill gas network at least quarterly. Comments The LFG Plan does not match the GMP with respect to the LFG and groundwater monitoring networks. The GMP states that P-203, P-206, and P-212 (among others) will be converted to groundwater monitoring wells. The LFG Plan says that P-202 through P-206, P-210, P-212, and P-116 will be converted to LFG probes. The Site Monitoring Plan drawings in the LFG Plan do not match either the LFG Plan text or the GMP. Recommend asking for clarification. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * 2. The LFG Plan does not identify off-site structures within 1,000 feet as being in the LFG monitoring network, as required in the VSWMR (9VAC B.2.d). Suggest requesting information as to whether there are any off-site structures within 1,000 feet of the waste disposal unit, and if so, justification for not including them in the LFG monitoring network. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * Landfill Gas Remediation 9VAC C Complete Incomplete Adequate Area of Concern Must describe response actions to methane exceedances, and require a landfill gas remediation plan when compliance limits are exceeded. Comments Adequately addressed. * * * * Golder Associates Inc., Reference No Page 21 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

22 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) Odor Management 9VAC D Complete Incomplete Adequate Area of Concern Must develop and implement an odor management plan upon notification from the DEQ. Comments An Odor Management and Control Plan for the facility, dated July 15, 2010, was located on the internet. An Odor Management Plan was initially prepared in 1998 to comply with Condition 22 of the CUP, and has been updated periodically. See SCS s response, attached. Golder s Response: The response is acceptable. * * * * 2. Given the thickness of the proposed waste mass, the facility location in an urban area, and the potential for system failure based on the elevated stresses and loads that will exist at full buildout, Golder recommends that the Odor Management and Control Plan be updated for a contingency response to an elevated temperature event (and the associated odor) in the landfill such as has occurred at Bridgeton (MO), Countywide (OH), Murfreesboro (TN), and Waimanalo (HI). See SCS s August 28, 2015, response, attached. Golder s Response: The response is acceptable. * * * * 4.3 County Wastewater Discharge Program Based on review of the available documents and in consideration of the potential gradient control flows that may require management as leachate should they become impacted, Golder recommends development of a pre-treatment plan for the potential treatment and discharge the gradient control water. This plan is significant because, if the gradient control water becomes impacted such that it can no longer legally be discharged under the allowable non-stormwater discharge provisions of the facility s Virginia Pollutant Discharge Elimination System (VPDES) stormwater permit (subject to $32,500 per day fines), immediate alternative management means will be required if insufficient materials are not present to counteract the hydrostatic buoyancy pressure on the liner (i.e., if sufficient counter weight is present, the facility operator could temporarily terminate the pumping activities as needed until such time as the means for an alternative disposal are put in place). Failure to counter act the hydrostatic pressure in a timely manner may result in separation of the liner from the vertical liner mounting system resulting in structural failure and likely unrepairable damage to the liner system. The pre-treatment plan should address the requirements (permitting and operational) for the likely discharge location (e.g., Chesterfield County Sewer or industrial wastewater surface discharge to Swift Creek). The pre-treatment plan should address in detail the means and methods for treating the wastewater to mitigate predicted elevated concentrations (or observed based on existing leachate and Golder Associates Inc., Reference No Page 22 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

23 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) landfill gas condensate monitoring data) of commonly observed MSW leachate and landfill gas condensate contaminants, including, but not limited to: Acetone, Methyl ethyl ketone, Ammonia, Biological oxygen demand (BOD), and Chemical oxygen demand (COD). Endpoint target concentrations for treatment should be based on County discharge standards [i.e., Total Toxic Organic (TTO) limits plus any parameter specific limitations] and/or Virginia Water Quality Standards, including Chesapeake Bay Total Maximum Daily Load (TMDL) limitations if a surface discharge is anticipated. If a County sewer discharge is envisioned, Golder recommends that a letter of capacity availability be obtained from the County to ensure that the County will be able to manage the additional flow if required. If a private pump and haul disposal is envisioned, a letter of capacity availability should be obtained from the potential disposal company. Additionally, unless the facilityoperator is able to obtain a letter of capacity or similar assurance for additional disposal capacity via the County sewer, Golder recommends that a bypass flow analysis be performed to determine the minimum amount of on-site storage capacity that may be required to manage impacted gradient control water in the event that surface discharge is no longer a viable option pending the completion of arrangements for alternative disposal means. See SCS s August 23, 2015, response, attached. Golder s Response: The response is generally acceptable. The overriding concern with this comment is that operation of Cell 28 may preclude the discontinuation of the gradient control system operation, and if that water (100% or some smaller fraction) were to become impacted with one or more landfill-related contaminants, or was determined to contain nutrients or other constituents in concentrations detrimental to the Chesapeake Bay, is there adequate space for current technology/retention time to treat the discharge to expected permit limits, since the discharge of this fluid to the Chesterfield County public sewer is likely to be precluded by the County based on design flow considerations of the existing system. Based on the design of the gradient control system, a worst-case scenario would require Shoosmith to be able to treat flows based on the April 2008 observed flow data provided by the quarry operator. 4.4 County Utilities * * * * There has been concern expressed by various County departments regarding the design of the internal Leachate system. A supplemental plan needs to be created to address the interior layout of the leachate collection system as it drains to the pretreatment area. Additionally, as various cells are raised and capped, a phasing plan needs to be shown indicating whether or not the leachate collection lines will be periodically relocated or will be buried under an extreme amount of cover. The plan should indicate the material types of the collection lines and whether or not they are cased (sleeved). The plan should have the grading dithered and the sanitary collection system darkened for visibility. Finally, provide information on the pump system which will limit the effluent to the maximum discharge of 120,000 gpd or 83 gpm. See SCS s August 23, 2015, response, attached. Golder s Response: The response is generally acceptable, although Golder recommends that the option to provide secondary containment piping for the leachate forcemain be made a mandatory requirement in areas where that piping is not located over a liner system. Golder Associates Inc., Reference No Page 23 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

24 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) 4.5 VPDES Stormwater Monitoring Program Stormwater 9VAC Complete Incomplete Adequate Area of Concern Dischargers of stormwater associated with industrial activity are required to apply for an individual permit or seek coverage under a promulgated stormwater general permit Comments Permit Condition I.F.20 in Module I states that, prior to operating in the Quarry Cell, the operator shall submit to the DEQ a request to discharge stormwater off-site and/or through the facility s stormwater detention ponds. DEQ will evaluate the need for a new or revised VPDES or Water Permit at that time. Recommend requesting a stormwater management plan to include state and local permit requirements. 2. DEQ also noted in Permit Condition I.F.20 that the facility may be subject to additional MS4 requirements from Chesterfield County. Recommend requesting clarification from County staff. See SCS s August 23 and 28, 2015, responses, attached. Golder s Response: Response is adequate. 4.6 VPDES Gradient Control Discharge Monitoring Program Gradient Control Water 9VAC Complete Incomplete Adequate Area of Concern Must develop and implement a monitoring program for the gradient control water, in conjunction with the groundwater monitoring program (see Section 3.1.2). Must request a permit to discharge to surface water. Comments Permit Condition I.F.20 states that, prior to operating in the Quarry Cell, the operator shall submit to the DEQ a request to discharge groundwater from the gradient control system off-site and/or through the facility s stormwater detention ponds. DEQ will evaluate the need for a new or revised VPDES or Water Permit at that time. Recommend requesting a gradient control water management plan that addresses the means and methods that will be used to manage the water, including expected volumes, quality, locations, permits, contingency plans, and emergency response actions. See SCS s August 23 and 28, 2015, responses, attached. Golder s Response: Response is adequate. Golder Associates Inc., Reference No Page 24 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

25 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) 5.0 RESPONSES TO COUNTY CONCERNS 5.1 Landfill Depth The overall potential depths of the Quarry Cell raise unique design challenges. These arise because the following major issues relating to depth: The overburden pressures on pipes that comprise the landfill gas, gradient control, and leachate control systems are larger than for typical landfills; and The ability to remedy any problems with these systems is significantly more difficult and more expensive than with landfills that have lesser depths. The maximum safe fill depth for solid waste in a MSW landfill is dependent on various operating and design constraints. As proposed, Cell 28 appears to have a maximum fill depth of 405 feet with a maximum height of approximately 295 feet above mean sea level (MSL) where Cell 28 abuts at-grade Cell 27. It is noted that Proffered Condition No. 1 in the Facility s existing Conditional Use Permit allows the landfill height to extend to 380 feet above MSL, which could result in a maximum fill depth in excess of 500 feet. At this time, the theoretical maximum operating depth for MSW based on existing technology is hypothetically only limited by material specifications. It is Golder s opinion that the engineering systems can be engineered to accommodate these depths. Generally, we are satisfied that the gradient control and leachate collection systems can be engineered to withstand the required stresses. We are less confident that the components of the landfill gas (LFG) system, particularly the lateral collectors, connections to the vertical gas collectors, and the vertical gas collectors will continue to function as designed as filling of the Quarry Cell progresses. Because of the importance of these systems in successful landfill operations, we believe that the components of these systems (mostly the piping systems) that are subjected to high stresses be very carefully designed with consideration for not just failure but unacceptable deflection, unacceptable differential settlement, and down-drag forces. In addition, we have reviewed SCS s response to our original comments on these systems. We support the redundancies outlined for these systems and recommend that they be incorporated into the permit application, the construction-level designs, and the permit. This redundancy would include the ability to use multiple pipes to pump both the gradient control system and the leachate system. We also recommend that the redundant features of the LFG collection system be included in the permit application and permit. Of particular interest is the concept of providing a permeable layer just inside the liner system up the quarry walls that would allow access to collect LFG around the perimeter of the Quarry Cell, and the concept of providing both aggregate and geosynthetic materials along with the lateral LFG collectors to aid in collecting LFG in the event of pipe blockage. We recommend that the functionality of these systems be carefully monitored as waste filling progresses. If problems with pipe failures or inability to collect leachate, groundwater, or LFG are encountered, they will be easier to remedy while the depths of waste are lower. Finally, there have been several significant system failures in the industry associated with MSW landfills that resulted in significant odor management issues. Some of these failures may in part be associated with the depth of fill. Review of these failures suggests that leachate recirculation and inadequate or poorly operated LFG collection and control systems may be a common root cause for the failures. Therefore, until these failures are better understood and additional studies are completed on the maximum safe depth of MSW fill, Golder recommends that redundant systems with significant factors of safety be used in the construction and operation of Cell 28 to ensure that the LFG collection and leachate collection systems can be operated to design specifications at waste depths in excess of 400 feet, that leachate recirculation not be performed (in Cell 28), and that contingency plans for odor controls be maintained, reviewed, and updated annually to reflect state-of-the-art technology. Golder recommends Golder Associates Inc., Reference No Page 25 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

26 SOLID WASTE PERMIT APPLICATION REVIEW (09/03/15) that these requests be incorporated into the Facility s solid waste permit as enforceable conditions. These recommendations should be sufficient to remove self-limited biologically-generated heat from the MSW, which will protect the engineered systems from pressure/heat-related failures, provided that the systems are operated in a manner that prevents the introduction of atmospheric oxygen or other oxidizers to the waste mass. 5.2 Hydrostatic Pressures from Groundwater We have reviewed SCS s plans and their response (including calculations) to our comment about hydrostatic pressures. We generally find their response acceptable. The calculations indicate that the consolidated MSW density should prevent the liner from separating from the quarry wall solely due to lateral hydrostatic pressure. The calculations do not reflect differential settlement, which is expected to be more significant in the center of the cell as opposed to along the quarry walls. Therefore, Golder recommends that significant care be given to the sacrificial wall lift and MSW placement and compaction operations along the vertical quarry faces to ensure that these materials do not flow towards the center after filling and compaction operations have been completed. Furthermore, we believe that it will be important to carefully monitor groundwater levels and ensure that the counteracting waste depths and pressures are adequate to resist the hydrostatic forces prior to discontinuing the operation of the gradient control system. Shoosmith may wish to include transducers in selected areas of Cell 28 (both inside and outside of the liner system) to monitor the accumulated stresses for verification purposes. Additionally, Golder recommends that the gradient control system shutdown be managed with a phased approach to ensure that the engineered systems continue to operate to design specifications under the additional stresses associated with the increased external hydrostatic pressures. Specifically, a minimum of 1 year should be allowed to elapse between operational termination of successively higher gradient control zones to ensure that leachate generation rates do not unexpectedly increase due to groundwater inflow to the leachate system. As part of the leachate generation evaluation, a demonstration should be prepared by the facility operator for each level that is inactivated using standard statistical procedures to demonstrate leachate generation flow stability (or decline). Golder recommends that this operating condition be made an enforceable permit condition. 5.3 High Temperatures We have reviewed SCS s response to concerns about high temperatures and generally find their response acceptable. While high temperature issues are not a routine concern at United States landfills, they do occur and the precise reasons why are not always known. We recommend that the temperatures in the Quarry Cell be carefully monitored as waste filling progresses (with transducers if necessary), especially in conjunction with the leachate recirculation if allowed by the County, so that adjustments to recirculation amounts or other remedies can be implemented prior to achieving full waste depths (see comment 5.1 in which Golder recommends that leachate recirculation not be allowed for Cell 28). If recirculation is requested by Shoosmith Bros. Inc. and approved by the DEQ, Golder recommends that this operating condition be made an enforceable permit condition. Golder Associates Inc., Reference No Page 26 of 26 g:\projects\chesterfield county\0a.environmental\ shoosmith permit review project\ submittal to the county\ round 2 permit application review standalone.docx

27 ATTACHMENT 1 Environmental Consultants Midlothian Turnpike Suite 305 FAX Midlothian, VA August 28, 2015 File No Mr. Michael G. Williams, PG Associate Senior Consultant Golder Associates Inc West Laburnum Avenue Suite 200 Richmond, Virginia Subject: Case #97SN0206 Follow-Up Response to Golder s Comments on Solid Waste Permit Technical Review 8/12/15 Draft Shoosmith Sanitary Landfill (Solid Waste Permit No. 587) Chester, Virginia Dear Mr. Williams: Thank you for the opportunity to discuss our responses to the draft technical review prepared by Golder Associates on August 24, Based on our discussions, we understand that Golder is requesting additional clarification as outlined in our meeting. In addition, we have also received comments from you via on August 26, Listed below are responses to your comments (in italics). FOLLOW-UP REVIEW MEETING COMMENTS Comment 1: Provide a Water Management Plan that compiles source water, permit information (existing and proposed), permit limits, volumes, and remedial and disposal options for the different water sources that will be encountered as part of the Cell 28 construction and operation activities.. Response 1: See the attached document titled Liquids Management Plan for Quarry Waste Disposal Unit. This Plan consolidates the description of the design criteria for the systems that will manage leachate, gradient control water, and stormwater associated with the Quarry Cell, which are contained in various Attachments of the Solid Waste Permit Amendment documentation. The specific issues that Golder has identified are addressed in Section (stormwater run-on control), Section (gradient control system storage capacity), Section (gradient control sampling), Section (gradient control system contingency measures), and Section 4.2 (VPDES Permit provisions. Comment 2: Provide a Groundwater Monitoring Network plan for Cell 28 after the gradient control system is turned off. We understand that this plan will reflect Shoosmith s decision to either terminate or continue operating the uppermost two gradient control systems with gravity discharges.

28 Mr. Michael G. Williams, PG August 28, 2015 Page 2 ATTACHMENT 1 Response 2: See attached Drawing 5, which addresses Comment 2. Comment 3: Provide more detailed response to comment 4.2.4, particularly with respect to how conditions for proposed Cell 28 are different and are expected to be different from those in the example elevated temperature landfills provided. Response 3: Further discussion regarding the response to Comment of Golder s comment letter related to the Facility s Odor Management and Control Plan and the issue of elevated temperatures. The existing Odor Management and Control Plan is reviewed and a report is submitted to VDEQ on an annual basis. During the next Plan review cycle, the Facility will evaluate whether it is appropriate to incorporate a contingency response that anticipates an elevated temperature event based exclusively on the premise that such an event has occurred at a few MSW landfills in the US. Based on SCS experience working at several of the facilities identified in the comment, as well as other landfills experiencing elevated temperatures, we offer the following discussion points to differentiate conditions at the Shoosmith Landfill compared to our understanding of conditions at these other facilities for consideration: At the Countywide LF site in Ohio, the triggering event that initiated a subsurface exothermic chemical reaction as well as several other landfills was related to the acceptance and placement of secondary metals waste (aluminum dross). This material was placed in a contiguous layer which came in contact with copious quantities of liquids and initiated a reaction that produced significant heat. For the record, the Shoosmith Sanitary Landfill has not received special waste consisting of aluminum dross from smelting facilities (or other secondary metals wastes) in quantities that approach those that were disposed at Countywide or other landfills that have experienced elevated temperatures attributed to an exothermic chemical reaction initiated by aluminum dross. SBI is well aware of the potential for such materials to produce these conditions when concentrated within the waste mass and in the presence of substantial liquids, and manages the small quantities of special waste materials that are accepted at the Facility to avoid such conditions. For the Bridgeton Landfill in St. Louis, which is also a quarry landfill, it is germane that waste filling commenced in about 1980, over 35 years ago. Further, Bridgeton has no bottom or sidewall liners, and is only equipped with a final cap. Bridgeton allowed groundwater to flow back into the waste mass through the unlined quarry side walls, and pumped the water level in the landfill lower than natural ground water level outside the quarry. This yielded a saturated waste mass in an unlined landfill. The Quarry Cell at the Shoosmith Landfill has been designed to include a Subtitle D equivalent liner systems on both the bottom and sidewalls and groundwater flow into the waste mass will be precluded through pumping of the gradient control water.

29 Mr. Michael G. Williams, PG August 28, 2015 Page 3 ATTACHMENT 1 Several other landfills that have experienced elevated temperature events experienced slope failures that exposed waste and which may have served as the triggering event to initiate significant heat by introducing oxygen into a large area of anaerobic waste mass. Because the Quarry Cell is confined by bedrock, the possibility of a slope failure that might expose waste to the atmosphere is extremely unlikely. Several other landfills that have experienced elevated temperature events engaged in prolific leachate recirculation activities that involved reintroduction of nearly 100 percent of the leachate generated at the landfill back into the waste mass. This yielded saturated conditions of the waste mass and resulted in wide-spread elevated liquid levels. The Shoosmith Landfill has discontinued leachate recirculation over the past several years. While the Facility has recirculated leachate in select cells in the past, and reserves the ability to perform leachate recirculation in the future in accordance with the Permit, at no time did the Facility recirculate more than 50 percent of the leachate being generated at the site. The Facility s existing Solid Waste Permit restricts the leachate recirculation operations to a maximum of 75 percent of the leachate generated at the site. The elevated temperatures at these sites were initially exhibited during landfill gas wellhead monitoring events. The average LFG wellhead temperatures measured at over 200 existing wellheads in the existing waste disposal units during the routine monitoring events at the Shoosmith Landfill are below the NSPS operational standard of 131 degrees F. The LFG temperature and leachate temperature data compiled over the past 15 years do not suggest reason for heightened concern related to elevated temperatures and the odors that have been experienced at these other facilities. In the event of an elevated temperature event, several of the contingency response measures that have been implemented at the sites mentioned, as well as other landfills experiencing elevated temperatures, could be implemented by the Shoosmith Landfill to mitigate malodorous emissions from the Quarry Cell. These measures may include, but are not limited to, the following: Installation of an interim exposed geomembrane cap (EGC) and near-surface gas collectors over portions of the Quarry Cell that are not part of the active working face to restrict emissions of malodorous organic acid constituents present in the gas produced by subsurface reactions. Increased density (tighter spacing) for installation of LFG collection system components to provide improved collection efficiency and redundancy in the zone-of-influence exerted near the landfill surface. Installation of vapor collection systems at the on-site leachate pre-treatment facility, sideslope contingency riser access vault, and other leachate system infrastructure to collect and treat odorous emissions resulting from leachate management activities. Comment 4: Provide an updated detail on the detail sheet for Comment question 7. Response 4: See attached revised Sheet 77.

30 Mr. Michael G. Williams, PG August 28, 2015 Page 4 ATTACHMENT 1 Comment 5: Provide calculations to support the response under Comment regarding the potential build-up of hydrostatic forces outside of the liner system. Response 5: SCS has also included a calculation to follow-up on the response to Comment of the original document addressing the potential build-up of hydrostatic forces outside of the liner system and the potential for deflection of the liner system inward in the event of gradient control failure, which was discussed during our meeting. Comment 6: Discussion on Comment 1.3 pertaining to Proffered Condition No. 25 regarding filing of restrictive covenants. Response 6: SBI accepts Golder s recommendation and will record the restrictive covenants within 90 days of VDEQ s issuance of an amended Solid Waste Permit incorporating the engineering design for the Quarry Cell. FOLLOW-UP REVIEW COMMENTS Comment 1: Per request, for metals at this point we would recommend the Table 3.1 column A metals field filtered with a 0.45-micro filter for consistency during future apples-to-apples evaluations. Response 1: SBI finds the proposed sampling for metals acceptable. Comment 2: The County s technical comment on radio nuclei appears to need clarification. The County agrees that the mining activities themselves should not be adding any radioactivity to the rock, nor should the mining activities impact the rate of radioactive decay. Rather our question was relative to the natural background radioactivity in groundwater that discharges from highly weathered (and leached) saprolitic (former granite) overburden soils and the upper sections of weathered granitic bedrock relative to the flows that will be expected from the gradient control system. Specifically, is there a potential for increased radioactivity (alpha, beta, and/or gamma) in the expected groundwater flow that will be captured from the groundwater gradient control system relative to natural discharges to Swift Creek, particularly those levels of the gradient control system that are collecting groundwater from relatively freshly exposed bedrock surfaces where previously unleached elements/minerals may now be subject to leaching. If so, what is that difference expected to look like based on site sampling data, journal citations, geochemical modeling results, and/or other information? Response 2: The issue, as we understand, has to do with whether the presence of the liner system within the quarry will concentrate radioactivity within the collected gradient control water, thereby leading to discharge water that has a greater amount of radioactivity than that which naturally seeps from the granite bedrock and into Swift Creek. Granite, the type of bedrock present in the quarry, has within it naturally occurring radioactive materials (NORM). Concentrations of NORM will vary depending on location. NORM in granite typically takes the form of uranium-238, which is common in most types of rock and soil, but can be more prevalent in granite. Radium-226 is a decay product of uranium-238. When this type of radium decays, it produces radon-222, an inert gas with a half-life of about 4 days.

31 Mr. Michael G. Williams, PG August 28, 2015 Page 5 ATTACHMENT 1 Thorium can also be present in granite. Radium-224 is a decay product of thorium. Radium-224 decays to radon-220 (also known as thoron), which has a half-life of 54 seconds. Thus, the primary threat from NORM in granite is the production of radon gas. According to the USEPA Radon Risk Map for Virginia published by the Virginia Department of Health (VDH), Chesterfield County lies within the zone with the highest potential for radon gas exceeding the USEPA s recommended action level. Radon gas can accumulate in structures and basements, leading to a potential exposure risk. Radon levels vary widely depending on the location and type of structure. Radon can also exist in natural groundwaters; however, the risk posed by radon in groundwater is much lower and manifests itself when radon gas is allowed to degas from groundwater and accumulate. If radon gas were present in the groundwater captured by the gradient control system, the quantity of gas would be reduced through volatilization as the water is discharged and stored in Sediment Basin #7 prior to discharge to Swift Creek. Thus, the level of radon (and its accompanying radioactivity) present in the water reaching Swift Creek should be no different than that naturally discharged from springs or seeps into Swift Creek. However, to address further concerns regarding radon, SBI offers to evaluate background levels of alpha, beta, and gamma radiation in groundwater prior to development of Cell 28. Background would be established using the same methods discussed in SBI s Response 2 under of the Response to Golder s Comments on Solid Waste Permit Technical Review 8/12/15 Draft dated August 23, Every 5 years thereafter, groundwater samples would be collected to evaluate changes in radioactivity, if any. Thank you again for the opportunity to provide these responses. SBI and SCS look forward to continuing to work with the County to address questions regarding the landfill operation or construction of the Quarry Cell. Please contact either of the undersigned or Bruce Coble of SBI at (804) if you have questions pertaining to our responses or require additional information. Sincerely, Charles J. Warren, PE Senior Project Engineer Robert E. Dick, PE, BCEE Project Director SCS ENGINEERS CJW/RED:asd cc: Bruce Coble, SBI Enclosures

32 ATTACHMENT 1 LIQUIDS MANAGEMENT PLAN FOR QUARRY WASTE DISPOSAL UNIT SHOOSMITH SANITARY LANDFILL CHESTER, VIRGINIA SOLID WASTE PERMIT NO. 587 Prepared for: Shoosmith Bros., Inc Lewis Road Chester, VA (804) Prepared by: SCS ENGINEERS Midlothian Turnpike Suite 305 Midlothian, VA (804) August 27, 2015 File No Offices Nationwide

33 Liquids Management Plan ATTACHMENT 1 Table of Contents Section Page 1.0 Introduction Leachate Management Estimated Leachate Quantities Scenarios Considered Results of HELP Modeling Leachate Collection Drainage Layer Design Leachate Collection Pipe LCS Design Standard Leachate Removal System Collection and Storage Units Leachate Treatment or Disposal Leachate Recirculation Leachate Seep Management Gradient Control Introduction Gradient Control System Background Groundwater Inflow Rate Calculations Overview of Management Strategies Short-Term Design Solutions Long-Term Design Solutions Gradient Control Sampling Gradient Control System Contingency Stormwater Management Run-On Control System Peak Flow Design and Performance Run-Off Control System VPDES PERMIT Background Effluent Limits, Monitoring, and Special Conditions Conditions Applicable to All VPDES Permits Stormwater Pollution Prevention Plan Landfill-Specific Requirements Shoosmith Sanitary Landfill i 8/27/15

34 Liquids Management Plan ATTACHMENT INTRODUCTION The Shoosmith Sanitary Landfill was initially permitted as Solid Waste Facility Permit No. 211 on September 29, 1976 and is currently operating under Virginia Solid Waste Facility Permit No. 587, issued by the Virginia Department of Environmental Quality (VDEQ) on December 6, 1995 and amended thereafter as outlined in Section I.G of Permit Module I. It is located in the County of Chesterfield, approximately 3 miles northwest of the Town of Chester and is positioned at the intersection of State Route 10 and Lewis Road. The landfill property encompasses approximately 506 acres. This Liquids Management Plan (LMP) addresses the portion of the landfill designated as the Quarry Waste Disposal Unit (also sometimes termed the Quarry Cell, the Quarry Fill Area, or the Quarry Landfill). The Quarry Waste Disposal Unit is identified as Cell 28. The northern portion of the landfill facility property contains the Dale Quarry. The Dale Quarry is an active granite quarry operated by Vulcan Materials Company (Vulcan) on a leased portion of the property. The existing footprint of the quarry pit (both inactive and active sections) is approximately 90 acres or so. The portion of the quarry pit (both inactive and active sections) that is positioned within the existing 370-acre Waste Management Unit Boundary (WMUB) and is available for solid waste disposal is approximately 82.6 acres. This LMP provides a summary description of the leachate collection and removal system (LCRS), the Gradient Control System (GCS), and Stormwater Controls that are discussed elsewhere in the Solid Waste Permit Amendment Application for the Quarry Waste Disposal Unit. Detailed descriptions of each system can be found within the Leachate Management Plan, Gradient Control Plan, and the Design Report. Additional information regarding the layout and design of these systems is also included the design drawings. 2.0 LEACHATE MANAGEMENT 2.1 ESTIMATED LEACHATE QUANTITIES The EPA Hydrologic Evaluation of Landfill Performance (HELP) computer model version 3.07 was used to perform water balance analyses for the Quarry Fill Area. The HELP model performs a sequential daily water balance on a liner system profile to estimate stormwater runoff, evapotranspiration, infiltration of leachate into the LCRS, lateral drainage within the LCRS, and leachate percolation through the liner. Results from the HELP model were used to estimate leachate generation, including: Average monthly leachate quantities. Annual leachate flow rates at 5-year increments of operation for 20 years, or until closure, whichever date is earlier (per 9 VAC A.1). The life expectancy of Cell 28 is estimated to be approximately 20 years; therefore, four 5-year increments have been developed and presented herein. Shoosmith Sanitary Landfill 1 8/27/15

35 Liquids Management Plan ATTACHMENT 1 Peak leachate generation rates during the life of the landfill. Leachate storage capacity based on average monthly data. Confirm that the leachate collection layer is adequate to maintain less than 30 cm (12 inches) of leachate head on top of the liner. To estimate leachate generation quantities and flow rates using the HELP model, multiple scenarios for various waste heights and various liner system configurations were established. These scenarios are discussed below Scenarios Considered A summary of the HELP Model scenarios and pertinent flow rates are provided in Appendix A of the Leachate Management Plan, as well as copies of the input/output data. There are several options for lining Cell 28 along the bottom of the quarry and its sidewalls. The liner systems modeled are described below. For each liner system, modeling scenarios were run at multiple waste depths (10-, 30-, 100-, and 300-foot). For scenarios with a Subtitle D composite liner system and waste depths of at least 30 feet, leachate recirculation was considered Bottom Liner For Cell 28, the bottom liner system design incorporates a prescriptive Subtitle D composite liner system or an alternate bottom liner. The two bottom liner systems for the Quarry Cell are described below: The Subtitle D composite liner system consists of the following components (from top to bottom): inch granular drainage layer with a minimum permeability of 1 x 10-3 cm/sec. 2. Geocomposite drainage net (GDN) with a minimum transmissivity of 4.0 x 10-4 m 2 /sec at 30,000 psf or otherwise specified in the Technical Specifications. 3. Synthetic flexible membrane liner (FML) consisting of a dual textured 60-mil HDPE geomembrane. 4. Soil liner consisting of 2 feet of compacted soil with permeability no greater than 1 x 10-7 cm/sec. An alternate bottom liner (ABL) consisting of the following components (from top to bottom): inch granular drainage layer with a minimum permeability of 1 x 10-3 cm/sec. 2. Geocomposite drainage net (GDN) with a minimum transmissivity of 4.0 x 10-4 m 2 /sec at 30,000 psf or otherwise specified in the Technical Specifications. 3. Synthetic flexible membrane liner (FML) consisting of a dual textured 60-mil HDPE geomembrane. Shoosmith Sanitary Landfill 2 8/27/15

36 Liquids Management Plan ATTACHMENT 1 4. Geosynthetic clay liner (GCL) with a maximum hydraulic conductivity of 5 x 10-9 cm/sec or otherwise specified in the Technical Specifications. 5. Synthetic flexible membrane liner consisting of a dual textured minimum 40-mil HDPE geomembrane. 6. Soil layer consisting of 1 foot of compacted soil subbase. Design parameters and assumptions used in preparing the bottom liner scenarios for the HELP Model include: 3.0 percent minimum slope on leachate drainage layer; 350 feet maximum drainage length to collection piping; Default climatological data for Richmond, Virginia; FML pinhole density modeled as 5 holes/acre; FML installation defects modeled as 5 holes/acre; and, FML placement quality modeled as poor (4) Sidewall Liner The liner system for the Quarry Cell s sidewalls is comprised of two basic elements: the sidewall bench configuration and the sidewall vertical configuration, which reflects slopes varying from 45 to 90 degrees. Each of these sidewall elements has two liner system options: one employs a structural member, such as concrete or vinyl sheeting, for strength and support, and the other option utilizes soil (either compacted soil or mechanically-stabilized earth). The sidewall liner system options consist of the following components: Sidewall bench (from top to bottom) - Option 1: 1. Woven geotextile; 2. GDN; 3. Synthetic flexible membrane liner consisting of a dual textured 60-mil HDPE geomembrane; and, 4. GCL with a maximum hydraulic conductivity of 5 x 10-9 cm/sec (supported by a concrete slab, which is not modeled in HELP). - Option 2: 1. Woven geotextile; 2. GDN; 3. Synthetic flexible membrane liner consisting of a dual textured 60-mil HDPE geomembrane; and, inches of compacted soil with a maximum permeability of 1 x 10-5 cm/sec. Shoosmith Sanitary Landfill 3 8/27/15

37 Liquids Management Plan ATTACHMENT 1 Sidewall vertical element (from inside to outside) - Option 1: 1. Woven geotextile; 2. GDN; and, 3. Synthetic flexible membrane liner consisting of a dual textured 60-mil HDPE geomembrane (supported by a structural member, either concrete or vinyl sheeting, which is not modeled in HELP; refer to discussion below). - Option 2: 1. Woven geotextile; 2. GDN; 3. Synthetic flexible membrane liner consisting of a dual textured 60-mil HDPE geomembrane; and, inches of compacted soil with a maximum permeability of 1 x 10-5 cm/sec. Assumptions used in the modeling include: The apparent (or effective) interior sideslope of the quarry walls, including near vertical sections, considering horizontal benches, is about 45 degrees. This results from a sidewall liner system which is generally vertical between the benches, with benches spaced approximately every 40 feet vertically or so. Based on review of historical documentation for other quarry landfills (1995 Bristol, VA Quarry Balefill permit application) and review of documentation developed by the author of the HELP Model (Dr. Paul Schroeder),. Iit is recognized that the HELP model is not precise when analyzing steep sideslope conditions. Therefore, for the purposes of modeling the sidewall liner, the anticipated slopes on the sidewall benches were used. 2.0 percent minimum slope on leachate drainage layer for sidewall bench Option 1 (with FML/GCL), which is a conservative input considering the minimum slope on the sidewall bench shown on the Permit Design Drawings and specified throughout the Permit documentation is 3 percent. Although the protective drainage layer is not required for the sidewall bench configuration, it may be included at the Owner s discretion in select areas to provide enhanced drainage along certain portions of the benches. Since the HELP Model is not structured to handle a drainage collection layer on top of another drainage collection layer, the protective drainage layer was modeled as a vertical percolation layer. Leachate conveyance was modeled in the GDN percent minimum slope on leachate drainage layer for sidewall bench Option 2 and sidewall vertical Option 2 (with FML/soil). Similar to sidewall bench Option 1, the protective drainage layer is not required for the sidewall bench configuration, although it may be included at the Owner s discretion in select areas to provide Shoosmith Sanitary Landfill 4 8/27/15

38 Liquids Management Plan ATTACHMENT 1 enhanced drainage along certain portions of the benches. As noted previously, the protective drainage layer was modeled as a vertical percolation layer and leachate conveyance was modeled in the GDN. 350-foot maximum drainage length for sidewall bench Option foot maximum drainage length for sidewall bench Option 2 and sidewall vertical Option 2. Default climatological data for Richmond, Virginia. FML pinhole density modeled as 5 holes/acre. FML installation defects modeled as 5 holes/acre. FML placement quality modeled as poor (4). The HELP model output for the sidewall vertical Option 2 configuration (FML/soil) is deemed to be a worst-case representation for the sidewall vertical Option 1 configuration, which has a structural member (either concrete or vinyl sheeting) in lieu of the 12 inches of compacted soil. A review of published literature suggests the hydraulic conductivity of concrete is less than 1 x 10-9 cm/sec, even when crack opening displacements of up to 100 microns form (see Permeability of Cracked Concrete, by Wang, Jansen, Shah, and Karr). Because the 6-inch concrete member (or 12-inch-thick vinyl sheeting with concrete flowable fill) is expected to be less permeable than the 12 inches of compacted soil with a maximum permeability of 1 x 10-5 cm/sec, the HELP model output for the sidewall vertical Option 2 configuration is considered applicable for Option 1 and is utilized where appropriate Leachate Recirculation Leachate recirculation is included only in scenarios with the prescriptive Subtitle D composite bottom liner system. Leachate recirculation may be initiated once the waste height is at least 30 feet from the leachate collection layer. The leachate being recirculated was modeled in HELP as subsurface inflow entering the top 2 feet of waste in each scenario. The recirculation rate was set at 7.86 inches per acre per year. This rate is approximately 75 percent of the average annual total leachate collected based on a waste height of 30 feet Results of HELP Modeling A summary of the HELP Model results for the established scenarios is provided in Appendix A of the Leachate Management Plan. Average annual leachate flow, maximum average monthly leachate flow, and peak leachate daily flow is presented in Table 1. The maximum head on the liner is also presented in Table 1. The maximum daily head (i.e., depth of leachate) on the liner for any scenario was estimated to be approximately 1.44 inches, which is well below the regulatory limit of 30 cm (12 inches) for depth of leachate stipulated in 9 VAC A.2. Average monthly leachate flow and volume data for each month are provided in Table 2. Shoosmith Sanitary Landfill 5 8/27/15

39 Liquids Management Plan ATTACHMENT Annual Leachate Production at 5-Year Intervals Annual leachate flow rates at 5-year increments of operation for 20 years are provided in Appendix B of the Leachate Management Plan, Tables 3 through 6. The 5-year leachate quantity estimates are provided in accordance with 9 VAC A.1, and provide a snapshot of potential leachate generation during the life of the Quarry Cell, which is estimated to be approximately 20 years. The following assumptions were used to establish the 5-year interval calculations: To establish waste height for each interval, it was assumed that approximately a quarter of the final waste height would be filled over the entire area of the cell during each 5-year interval. For example, if the final waste height will be 100 feet based on final contours, then the waste height for the initial 5-year increment was assumed to be 25 feet. The 10-year waste height was assumed to be 50 feet, and so on. To create a worst-case leachate production scenario, it was assumed that the initial 5- year interval would reflect the sump area having only 10 feet of waste and the remaining portions of the cell would be filled with waste. Although this configuration is not consistent with the phasing plans and would likely be difficult to achieve from an operational standpoint, this approach is believed to yield a conservative worst-case scenario for estimating leachate quantities and designing the infrastructure associated with the LCRS. Prior to year 5, rain caps and diversions will be used to minimize stormwater contact and infiltration into the waste mass. To relate waste heights with the HELP Model scenarios, isopach maps were prepared based on waste height as follows: Waste Heights Modeled In HELP (ft) Range of Waste Heights Grouped for the Isopach 10 0 to to to or more Figures 1 through 4 illustrating the isopachs are provided in Appendix B of the Leachate Management Plan. For purposes of creating a worst-case leachate production scenario, it is assumed that capping of the Quarry Cell will occur at the end of its life and no partial capping of the cell is reflected in the 5-year interval calculations. Per the calculations provided in Appendix B of the Leachate Management Plan, average annual leachate production will peak at approximately 28.2 million gallons at the end of year 5 and will decrease to 23.5 million gallons in year 20. Shoosmith Sanitary Landfill 6 8/27/15

40 Liquids Management Plan ATTACHMENT 1 Additional results derived from the HELP Model, such as maximum leachate flow through the leachate collection pipe, leachate flow to the sump, and 7-day leachate storage quantity are discussed in the appropriate sections below. 2.2 LEACHATE COLLECTION Drainage Layer Design A geocomposite drainage net (GDN) will be the primary leachate drainage layer on the bottom and sidewalls of Cell 28. Leachate from the waste mass will be filtered vertically through a protective drainage layer for the bottom liner on the quarry floor and through a woven geotextile on the sidewalls. Leachate will then flow through the GDN to collection pipes. Perforated leachate collection pipes above the liner and below the GDN will convey leachate by gravity to the collection sump. Details of the bottom liner and leachate collection systems are presented on the Detail Sheets of the Permit Design Drawings (Drawing Nos. 74, 76, and 77). Details of the sidewall liner and leachate collection systems are presented on Drawing No. 75. The Facility will deploy a rain cover over the drainage layer during the open cell condition for the disposal units. As the working face progresses across the cell, the rain cover will be removed. At the owner s discretion, rain covers may be used to cover large areas of open waste surfaces as filling moves around inside the Quarry Fill Area in order to minimize leachate production Soil Drainage Layer The protective drainage layer for the bottom liner is comprised of an 18-inch-thick layer of aggregate (often referred to as manufactured sand) defined in Technical Specification Section 02409, Leachate Drainage Layer. This granular drainage layer will have a minimum permeability of 1 x 10-3 cm/sec. The protective drainage layer will not be placed over the GDN for the sidewall vertical configuration (neither Option 1 nor Option 2). Although the protective drainage layer is not required for the sidewall bench configuration (Option 1 and 2), it may be included at the Owner s discretion in select areas to provide enhanced drainage along certain portions of the benches. As noted previously, since the HELP Model is not structured to handle a drainage collection layer on top of another drainage collection layer, the protective drainage layer was modeled as a vertical percolation layer and leachate conveyance was modeled in the GDN Bearing Strength The protective drainage layer's bearing strength has been analyzed assuming that the fracture strength of stone is in the range of 10,000 to 40,000 psi (per ACI 221R-96). The maximum load placed on the drainage layer will be a result from static loading of the maximum height of waste. This condition will induce a pressure of 283 psi upon the aggregate. Using these conditions, a factor of safety of approximately 35 was calculated. The supporting calculation is provided in Appendix C of the Leachate Management Plan. Based on the calculation, the protective drainage layer material is adequate to handle the anticipated loading. Shoosmith Sanitary Landfill 7 8/27/15

41 Liquids Management Plan ATTACHMENT Slope Stability The protective drainage layer will be placed over the GDN in areas where the bottom liner system is installed (either the Subtitle D composite liner system or the alternate bottom liner system). The minimum slope for these areas is specified to be 3 percent and the maximum slope for areas that receive the bottom liner system is likely to be no greater than 10 percent (e.g., existing access ramp into the pit), which is 5.7 degrees (10H:1V). The protective drainage layer will not be placed over the GDN for the sidewall vertical configuration (neither Option 1 nor Option 2). As noted above, the protective drainage layer is not required for the sidewall bench configuration, although it may be included in select areas to provide enhanced drainage along the benches. However, it will not be placed where the slope of the sidewall bench liner exceeds 33.4 percent (18.4 degrees or 3H:1V). The minimum peak friction angle for the interface between the protective drainage layer and the GDN is expected to be greater than 25 degrees (with Regression Adhesion of 0 psf) based on friction angle testing performed for construction of existing cells at this facility between 2004 and This value is the minimum peak friction angle specified for this interface as documented in the Design Report for the Quarry Cell and the Technical Specifications. For purposes of evaluating veneer stability, the sidewall bench configuration at 33.4 percent, which represents 18.4 degrees (3H:1V), was considered as a worst case scenario. In executing a veneer stability calculation, the tangent of the interface angle is divided by the tangent of the slope angle. Performing this simple calculation, the resulting factor of safety between the drainage layer interface with the GDN provides a factor of safety of 1.4. The calculation is provided in Appendix C of the Leachate Management Plan Filter Layer Over the bottom liner system, the protective drainage layer will act as a filter against clogging of the GDN. A stone filter will be provided around the leachate collection piping network as well. The stone filter will be an inert crushed stone material with the gradation of a VDOT No. 78 (or equivalent). The gradation of the stone filter was chosen to minimize clogging during the active life of the Quarry Fill Area and post-closure care period. The pipe and stone filter are sloped to allow for drainage of leachate toward the sump even in the event of localized clogging Geosynthetic Drainage Layer A GDN will be used to convey leachate to the collection pipes within Cell 28. The design parameters for the GDN to be used on the cell bottom and sidewalls are discussed in Technical Specification Section 13303, Geocomposite Drainage Net and Separation Geotextiles Transmissivity Transmissivity and associated hydraulic conductivity of the GDN are relative to loading (waste mass) over it. To account for this variation, a calculation was prepared to estimate transmissivity and hydraulic conductivity under anticipated loading conditions. The calculations are provided in Appendix D of the Leachate Management Plan. Calculated hydraulic conductivity values were incorporated into HELP Model scenarios. The GDN utilized for all bottom liner and Shoosmith Sanitary Landfill 8 8/27/15

42 Liquids Management Plan ATTACHMENT 1 sidewall liner configurations shall have a minimum transmissivity of 4.0 x 10-4 m 2 /sec at 30,000 psf, or otherwise specified in the Technical Specifications Creep Test results on commercially available GDN show satisfactory resistance to creep deformations and adequate residual flow capacity under loading conditions anticipated for this Quarry Cell. Factors reflecting creep and clogging were included in the transmissivity calculations presented in Appendix D of the Leachate Management Plan Sideslopes The GDN deployed in the bottom liner and sidewall bench configurations will be connected to the GDN deployed over the sidewall vertical element with ties and the panels overlapped as specified in the Technical Specifications. Where the GDN is installed as part of the liner system along the quarry rim, it will be secured via an anchor trench, the configuration and depth of which is depicted on the accompanying Permit Design Drawings. The minimum peak friction angle for the interface between the GDN and the textured FML is expected to be greater than 23 degrees (with Regression Adhesion of 0 psf) based on friction angle testing performed for construction of existing cells at this facility between 2004 and This value is the minimum peak friction angle specified for this interface as documented in the Design Report for the Quarry Cell and the Technical Specifications. Assuming the sidewall bench Option 2 configuration may be constructed with a slope of 2.9H:1V or greater, the GDN will be secured into an internal anchor trench excavated into the compacted soil and positioned adjacent to the VLSS, which may be necessary to provide adequate stability (the factor of safety for a 3H:1V sideslope was calculated to be 1.27). A stability calculation relative to the GDN and FML interface is provided in Appendix D of the Leachate Management Plan. The sidewall vertical liner system will involve placement of GDN in near vertical orientation. The options for anchoring of this material on the sidewall are depicted on the Permit Design Drawings (Drawing No. 75). Stability calculations for the sidewall liner system are provided in the Design Report Geotextile Filter Layer The GDN utilized for all bottom liner and sidewall liner configurations will have a geotextile filter over it. The geotextile (non-woven and woven) properties for use with the GDN are presented in Table in Technical Specification Section 13303, Geocomposite Drainage Net and Separation Geotextiles. Calculations are provided in Appendix E of the Leachate Management Plan that illustrate that the proposed geotextile is adequate for use as a filter Leachate Collection Pipe The leachate collection pipes will be constructed of high density polyethylene (HDPE) or equivalent pipe material. This material has been chosen based on its chemical resistivity and Shoosmith Sanitary Landfill 9 8/27/15

43 Liquids Management Plan ATTACHMENT 1 strength. The wall thickness and diameter have been selected for the strength requirements and provide adequate capacity to handle the anticipated leachate flows. The leachate collection pipes will have two, ¼-inch-diameter perforations spaced 120 degrees apart on 6-inch centers. A description of the materials and installation procedures for piping is contained in Technical Specification Section 02611, Pipes, Fittings, and Appurtenances. The maximum flow length between leachate collection pipes is 350 feet for the leachate collection system over the bottom liner. The maximum flow length between leachate collection pipes is 500 feet for the leachate collection system located along the sidewall benches. These drainage lengths were incorporated into the HELP Model scenarios discussed previously. The leachate collection pipes are designed with cleanouts to allow inspection and back flushing of the system. The locations of the cleanouts are shown on the Engineering Modification Plan (Drawing No. 54) of the Permit Design Drawings Sizing The leachate collection piping has been sized to handle the maximum leachate flows estimated based on the peak daily values for the worst-case scenario, which is represented by the initial 5- year increment. The maximum leachate flow rate collected by the piping for this hypothetical scenario is estimated to be 370 gpm (0.82 cfs) as presented in Table 7 of Appendix F of the Leachate Management Plan. The leachate collection header pipe layout is depicted on Drawing No. 54 and includes two main header pipes aligned together through the center of Cell 28. Two main header pipes are provided for redundancy as a conservative measure due to the relative large waste height and waste conditions of the Quarry Cell. These main headers will be 12-inch-diameter SDR-11 HDPE pipes positioned in a trench. Two perforated 8-inch SDR-11 HDPE collection laterals are also positioned in the center of Cell 28 in order to provide a maximum drainage length less than 350 feet. A perforated 6-inch SDR- 11 HDPE toe drain is provided at the base of the quarry sidewalls to convey leachate to the collection sump. Additional 6-inch leachate collection pipes are positioned along select sidewall benches to transport leachate from higher elevations to the collection sump. Calculations illustrating the adequacy of the main headers and laterals are provided in Appendix F of the Leachate Management Plan. Perforation sizing for leachate pipes is discussed in Technical Specification Section and will be 0.25-inches. Based on gradation, the VDOT No. 78 filter stone to be placed around the leachate pipes will have at least 80 percent of the aggregate greater than perforation size, thus minimizing clogging of the perforations and minimize the amount of aggregate that may fall into the pipe. Perforations are also spaced to adequately handle the anticipated leachate flow. A calculation related to perforations is provided in Appendix F of the Leachate Management Plan Piping Strength Hoop stress calculations were performed to demonstrate the leachate collection piping strength is sufficient to prevent wall crushing, pipe deflection, and critical buckling pressure from the static Shoosmith Sanitary Landfill 10 8/27/15

44 Liquids Management Plan ATTACHMENT 1 loading at the assumed maximum waste height. Calculations are provided for 6-, 8-, and 12-inch pipes. Based on the calculations, SDR 11 HDPE pipe is adequate to handle the anticipated loads when installed in trenches as shown on the Permit Design Drawings. The leachate collection pipe strength calculations are presented in Appendix F of the Leachate Management Plan LCS Design Standard As discussed above, the leachate collection system will maintain less than 30 cm (12 inches) of leachate on each of the various liner systems. 2.3 LEACHATE REMOVAL SYSTEM For Cell 28, one large sump will be equipped with three sideslope riser pipes. Two of the risers will be equipped with suitable high-head pumps. The remaining riser will remain empty to serve as an emergency access shaft. The leachate in the sump will be pumped to a transfer pump station along the rim of the Quarry Fill. From the transfer pump station, leachate will be pumped via forcemain directly into the Chesterfield County sanitary sewer system or pumped to the onsite wastewater pre-treatment system and then discharged after pre-treatment into the sanitary sewer system. The design incorporates an optional leachate abovegrade storage tank farm to store leachate prior to pre-treatment or discharge to sanitary sewer system. In the event the optional storage tank farm is constructed, the transfer pump station would be capable of pumping the leachate into the tanks. An emergency generator will be installed to provide back-up power as a contingency in the event of an extended power outage. The emergency generator will be capable of providing power suitable to operate the pumps in the leachate sump as well as the transfer pump station. The sideslope riser pumps were sized based on the average annual leachate flow rate (see Table 8 in Appendix G of the Leachate Management Plan) and anticipated total head. The pump will be required to handle at least 54 gpm at 341 feet total dynamic head (TDH). A total of two pumps will be installed to provide 100 percent redundancy. Sizing calculations are provided in Appendix G of the Leachate Management Plan. The leachate transfer pump station, which transfers leachate that is delivered from Cell 28 to the pre-treatment facility, (or to the optional storage tank farm), is designed to house a pair of submersible pumps rated at 120 gpm at 96 feet TDH discharging through a 6-inch HDPE forcemain. A flow rate equal to 120 gpm was selected for purposes of designing the pump station to provide at least twice the pumping rate of the sump pump in the event both sideslope riser pumps were activated or in the event that combined pumping from the (optional) storage tanks, and from the sump discharge was desired. The leachate forcemain sizing calculations are provided in Appendix H of the Leachate Management Plan. Shoosmith Sanitary Landfill 11 8/27/15

45 Liquids Management Plan ATTACHMENT COLLECTION AND STORAGE UNITS Leachate that is collected from Cell 28 will be pumped via forcemain to the on-site wastewater pre-treatment system and then discharged after pre-treatment into the Chesterfield County sanitary sewer system. Discharge rate to the sanitary sewer system will be regulated by valves to ensure gallon per minute (GPM) flow does not exceed any permitted limit. As noted previously, the Facility may opt to construct a leachate storage tank farm in the future. Provisions of the VSWMR require leachate storage facilities to have a minimum capacity equal to the expected production of leachate for any 7-day period for the life of the landfill. The VDEQ Guidance Document, dated 5/24/93, identifies the procedure for calculating the 7-day storage quantity. The maximum expected production of leachate during the life of the Quarry Cell is assumed to occur at the 5-year interval. It was also assumed that recirculation would be occurring over the Subtitle D liner system installed. The leachate flow rate for this scenario is derived from the maximum average monthly flow rate obtained from the HELP Model (see Table 9 in Appendix I of the Leachate Management Plan). The required minimum 7-day storage capacity is approximately 830,000 gallons (111,000 cf). Location and general details of the optional storage tank farm are provided on Drawing Nos. 54 and 76 of the Permit Design Drawings. 2.5 LEACHATE TREATMENT OR DISPOSAL Leachate recirculation is incorporated to provide for the reintroduction of leachate into the landfill mass as a management technique. Leachate that is not recirculated shall be discharged directly into the Chesterfield County sanitary sewer system or transported to the on-site wastewater pre-treatment system and then discharged after pre-treatment into the sanitary sewer system. Pre-treatment requirements, if any, will be determined by Chesterfield County Leachate Recirculation The Landfill may recirculate a maximum of 75 percent of the leachate generated in Cell 28 to a recirculation system. Leachate recirculation will not be initiated until at least a 30-foot depth of waste is in place. This height will allow the leachate more time to permeate through the waste and reduce the chance of short circuiting. Leachate recirculation will only occur over areas with a Subtitle D composite liner system, recirculation over an alternate liner system is approved by the VDEQ in the future. The following are possible options available to recirculate leachate. 1. The first method involves horizontal leachate recirculation which will disperse the leachate via perforated piping contained in stone or tire shred filled trenches. Such piping will be separate from horizontal landfill gas well piping. 2. The second method will be the construction of a bermed infiltration area where leachate will be introduced by surface application. 3. The third method is a vertical leachate injector. This method utilizes a perforated pipe surrounded by stone or tire shred which penetrates vertically into the waste. Shoosmith Sanitary Landfill 12 8/27/15

46 Liquids Management Plan ATTACHMENT 1 Method 1 - Horizontal Leachate Recirculation Horizontal leachate recirculation will incorporate the use of the horizontal injection wells, which may be equipped with a geonet. The leachate will gravity flow through the pipe and disperse into the waste through perforations in the pipe and the geonet. The system will be located so that their horizontal influence zone will not extend outside the limits of the liner. This zone is assumed to be a 1:1 slope as directed by VDEQ. Method 2 - Bermed Infiltration This method will involve the recirculation of leachate into a gravel or tire shred-filled bermed area located on the surface of the landfill. Leachate will be introduced by directly pumping leachate into the gravel or tire shred trench. The closest slope or working area should be greater than 50 feet away from the nearest edge of the berm. Leachate introduction should be avoided when winds are in excess of 15 mph or when the ground is frozen. Also, leachate recirculation should initially occur at intervals of no less than 72 hours to allow the leachate to absorb into the waste. After the landfill operator gains greater experience in the leachate recirculation process, the 72 hour interval may be gradually reduced, if warranted. Method 3 - Vertical Leachate Injector The vertical injector well method is similar to the horizontal leachate recirculation trench in that leachate is reintroduced into the waste by means of a perforated HDPE or PVC pipe surrounded by stone or tire shreds. As the method implies, the reintroduction will be performed by vertical intrusion into the waste as opposed to horizontal trenches. The leachate will be transferred from either the transfer pump station or the leachate storage tank farm to the leachate recirculation system via a connection in the forcemain. Calculations for the sizing of a leachate recirculation system to serve the Quarry Cell are provided in Appendix J of the Leachate Management Plan. A design flow rate of 50 gpm was used for the recirculation system. This design flow rate is equivalent to approximately 93 percent of the estimated maximum leachate pumping rate from the sump which is equal to 54 gpm. Thus, the recirculation system equipment and configuration presented in Appendix J of the Leachate Management Plan is sufficient to convey the 75-percent leachate recirculation rate used in the HELP Model. 2.6 LEACHATE SEEP MANAGEMENT Regular monitoring of the waste disposal unit sideslopes will be performed to identify the existence of surface seeps. The source of seeps shall be thoroughly investigated prior to selecting a remedy. Remedial actions will be implemented on a case-by-case basis. 3.0 GRADIENT CONTROL 3.1 INTRODUCTION The gradient control system is designed to manage groundwater flow into the Quarry Waste Disposal Unit during construction and operation. Shoosmith Sanitary Landfill 13 8/27/15

47 Liquids Management Plan ATTACHMENT GRADIENT CONTROL SYSTEM Background The gradient control system will be constructed to facilitate installation of the liner system by providing a dry working environment and preventing hydrostatic uplift of the liner system once in has been installed. The average flow rate and peak flow rate of groundwater were taken into account in designing the gradient control system. Estimates were prepared for both of these conditions to facilitate design of the system. The system is designed to efficiently remove the average flow rate, while having capacity to handle peak flow rates to prevent peak flows from saturating the underdrain system and pressurization of the liner system. The quarry is currently dewatered using a pump located in a sump on the lowest level of the quarry. The quarry has used this method to remove, precipitation, surface run-on, groundwater inflow and seepage from the adjacent impoundment from the pit since April The pump either discharges into Swift Creek downstream from the Quarry or directs the water to the Quarry s processing operation for use. The success of this system for purposes of dewatering the quarry for mining operations indicates that it can be used for the basis of the gradient control system. Between April 2008 and March 2009 an estimated 167,854,371 gallons were pumped from the quarry sump. This equates to an average of 459,875 gallons per calendar day or 319 gallons per minute. This time period was chosen because it includes pumping from the pit that was used for both discharge and for processing. Data from pumping previously collected does not account for water re-used elsewhere on the site Groundwater Inflow Rate Calculations Method To the extent possible data was taken from the existing quarry dewatering system to form the basis of the gradient control system. In some cases theoretical calculations and estimates were used to fill in gaps in the available data. An appropriate level of conservatism was used to account for any inaccuracies in the estimated data, which may result in capacity beyond what is required for gradient control. Prior to construction, any additional data available should be reviewed to confirm the accuracy of the calculated volumes. Pumping from the quarry is done on an infrequent basis and may be based on a processing need more that a goal to achieve a certain water level within the quarry. To account for inconsistencies in pumping frequency, a long period of time was used for the analysis. The water that is pumped from the quarry sump consists of precipitation, evapotranspiration, surface run-on, groundwater inflow, seepage from the adjacent impoundment and the change in water levels in the sump. Due to the limited nature of the data available on the impact of surface runon and seepage, those sources were ignored, creating a more conservative estimate. The groundwater inflow was therefore estimated to be: Groundwater Inflow=Pumped Volume Precipitation + Change in Storage + Evapotranspiration Shoosmith Sanitary Landfill 14 8/27/15

48 Liquids Management Plan ATTACHMENT 1 As noted above, a period of 12 months was used to account for any seasonal variations in the data Precipitation/Evapotranspiration The precipitation values used for calculation were estimated from local weather records and a quarry watershed of 64.5 acres. The annual precipitation for the quarry area for this time period was estimated to be inches, resulting in a total rainfall volume of 84,361,556 gallons. The evapotranspiration data was calculated using the EPA s HELP model version The total evapotranspiration was estimated to be inches, resulting in a volume of 53,065,293 gallons. By factoring in these values according to the equation shown above, the resulting groundwater inflow and change in storage is equal to 136,558,108 gallons per year Stormwater Run-On The stormwater run-on control system is generally described in Section 2.5 of the Design Report as consisting of existing stormwater features associated with the other waste disposal units (e.g., rim cells - Cells 25, 26, and 27) and new stormwater conveyance channels and sediment basins as shown on Sheet 70 of the Permit Design Drawings. Additionally, the existing berm that is positioned at the rim of the quarry pit will remain in place upon termination of commercial quarry operations, and be improved or enhanced prior to liner system construction activities where appropriate, to divert stormwater from the areas surrounding the quarry pit into conveyance features on the rim. During the stages of bottom and sidewall liner system construction, as well as during subsequent waste placement operations, stormwater will be intercepted along the upper sidewall benches and upper portions of the access ramp, utilizing berms, channels, flat panel drain pipes, or other suitable features. This will reduce the quantities of stormwater that would have the potential to be introduced into the backfill behind the VLSS or the aggregate subbase and, ultimately, require handling by the gradient control system infrastructure. These berms, channels, pipes, and other diversion features will direct stormwater to retention/detention zones within the quarry pit where it can be stored and/or pumped. In addition, during and after construction of the sidewall liner system, measures to cover the exposed top portion of the backfill behind the VLSS to reduce stormwater infiltration into the gradient control system will be implemented. Methods may include, but are not limited to, use of tarps, geomembrane sheeting, or soil cover to promote drainage away from exposed backfill. The Solid Waste Permit Amendment documentation does not include details depicting the alignment, configuration, dimensions, and materials of construction for such interim run-on control features, as described above, because such level of detail is not typically included at this permit documentation stage. Most of the stormwater that falls within the Quarry Cell will be handled by features described in section 2.5 or handled by stormwater control features that are progressively located within the waste filling area. The average stormwater flow from the remaining areas, which may potentially be handled by the gradient control system, represents approximately 12 percent of the peak monthly groundwater inflow used to size the gradient control pumps discussed in Section Shoosmith Sanitary Landfill 15 8/27/15

49 Liquids Management Plan ATTACHMENT 1 II.2.e of the Gradient Control Plan in Appendix H of the Design Report. This is within the factor-of-safety used to size the pumps and additional capacity can be created if necessary by adding pumps in the sideslope riser pipes, as well as using the gradient control collection pipe cleanouts for additional pumping. Thus, the design contemplates not only minimizing run-on reaching the groundwater control system during the early stages of filling but also management of heavy flows caused by an extreme weather event so that there will not be a buildup of hydraulic pressure under the bottom liner. Despite the systems outlined to prevent stormwater run-on, the contribution from this flow has not been removed from the quarry pumping for the purposes of these estimates. This will result in the design of system that is cable of performing even in the event of a failure of one of the controls outlined above Storage Pumping in the quarry is not based on achieving a certain level within the sump. Variations in sump level may have an impact on the volume data if the water levels are different for points in the reporting time period. Based on estimates of the sump size for the time period during which pumping was analyzed, the storage capacity is 10,638,310 gallons, which equates to 8 percent of the estimated groundwater inflow. For the peak monthly pumping rate, this could account for 32 percent of the 33,172,590 gallons Gradient Control System Storage The gradient control system will have a 12-inch thick drainage layer across the quarry bottom in addition to a sump in the excavated into the bottom of the quarry floor. If storage is needed for the discharge from the gradient control system, sediment basin #7 has an estimated storage based on the design drawings in excess of 50,000,000 gallons. This storage should be sufficient to allow the site to react to any changing conditions that may require treatment of the gradient control water Groundwater Inflow Estimation Based on the values described in the previous sections, the total groundwater inflow was approximated to be 136,558,108 gallons per year with a potential variation due to storage of 10,638,310 gallons. The average pumping rate based on these values would be between 240 gpm and 280 gpm depending on the impact of water storage. The peak monthly groundwater inflow rate based on peak pumping rates from the quarry is estimated to be 33,172,590 gallons with a potential variation due to storage of 10,638,310 gallons. This is equivalent to a peak pumping rate of up to 1,014 gpm. A multi-pump system with the capacity to achieve 125 percent of the peak pumping rate is recommended Overview of Management Strategies The gradient control system has been designed for the short-term and long-term for purposes of protecting the integrity of the liner system to collect, store, and manage gradient water pumped from the system, and prevent potential contaminated gradient water discharges from the site. During the construction and initial filling of the Quarry Waste Disposal Unit, the gradient control Shoosmith Sanitary Landfill 16 8/27/15

50 Liquids Management Plan ATTACHMENT 1 system will be used to pump groundwater out of the cell to prevent uplift of the liner system. When waste elevations reach a predetermined level to counter the buoyancy created by the groundwater, use of the system will be discontinued Short-Term Design Solutions Between the quarry floor and the liner system, a porous media layer will be installed to facilitate removal of groundwater. A system of piping as depicted on Sheet 52 of the Permit Design Drawings will be used to transport groundwater to the gradient control system sump. Calculations for pipe sizing and spacing are provided in the Gradient Control Plan in the Permit Design Report for the Quarry Waste Disposal Unit Long-Term Design Solutions The gradient control system will no longer be needed when waste filling reaches the 160-foot elevation above sea level. This waste mass will be sufficient to balance the upward pressure of groundwater on the liner. To minimize any potential negative effects (if any) of shutting off the gradient control system a phased approach may be used. The sump level gradient control pumps could be shut down one at a time to slow the rate of groundwater pumping. Alternatively the mezzanine level control pumps could be used for some length of time after the gradient control pumps in the sump have been shut off Gradient Control Sampling Five sampling points will be designated for the gradient control system. One for the gradient control sump and one for each of the mezzanine level collection pipes. These locations are noted on Sheet 69 of the Design Plans for the Quarry Waste Disposal Unit. The GMP and draft Permit Module I include analysis of the gradient control samples for VOCs. SBI believes that VOCs are the best indicators of a release from the quarry disposal unit. However, to address any further concerns, SBI will voluntarily analyze the first four gradient control samples for metals, biological oxygen demand (BOD), chemical oxygen demand (COD), ammonia, total nitrogen, phosphorus, as well as alpha, beta, and gamma radiation in groundwater following in-service placement of each gradient control system level. The initial four quarters of sampling results will be subjected to statistical analysis to determine statistically significant increases (SSIs) over background. For VOCs, an SSI will occur if a VOC is confirmed above the laboratory QL. For BOD, ammonia, and zinc (among other metals to be agreed upon for analysis), the Numeric Effluent Limitations listed in Table of the Virginia Pollutant Discharge Elimination System (VPDES) General Permit for Stormwater Discharges Associated with Industrial Activity (VAR05), Sector L for landfills, will be used to determine an SSI. Analytical results of the remaining analytes will be compared to site-specific background values. Shoosmith Sanitary Landfill 17 8/27/15

51 Liquids Management Plan ATTACHMENT Gradient Control System Contingency The gradient control pumps will have a back-up generator available for use in the event of a power failure at the site. Sufficient capacity is available in the sideslope riser pipes and cleanout pipes for the gradient control system to add additional pumps to achieve additional or contingency pumping capacity. In the event of contamination of the water pumped from the gradient control system, there is enough storage capacity identified in sediment basin #7 for long term storage of water pumped from the gradient control system. This would allow SBI to determine the best method to treat the contaminated water. This may include pump and haul operations to a treatment plant, discharge into the county sanitary sewer system, on-site treatment methods, or a combination of these treatment methods. The excess capacity available in the sediment basin will allow SBI to receive the necessary permissions to pursue the appropriate treatment method. 4.0 STORMWATER MANAGEMENT 4.1 RUN-ON CONTROL SYSTEM Peak Flow As noted previously, both run-on and run-off will be collected in the stormwater management system. Stormwater peak flows are calculated using the TR-55 or Rational Method as discussed in the Run-Off Control System Section and the calculations provided in Appendix I of the Design Report Design and Performance Design and performance of the overall stormwater management system is discussed in the Run- Off Control System Section below Run-Off Control System Design Volume Seven sediment basins will be constructed to handle the run-off from the landfill (the landfill area encompassed by Cells 22 through 28). Volume information for each of the basins is provided in Appendix I of the Design Report. For additional discussion of the sediment basins, see the Sediment Basin subsection below Design and Performance The run-off control system is designed for all stormwater conveyance channels, storm drains, benches, and pipe slope drains to convey run-off from at least a 25-year, 24-hour storm event. Flows were developed using the TR-55 or rational methods. All erosion and sediment control structures were designed and lined to adequately handle calculated velocities and depths of flow Shoosmith Sanitary Landfill 18 8/27/15

52 Liquids Management Plan ATTACHMENT 1 resulting from a 24-hour, 25-year storm event. Calculations are provided in Appendix I of the Design Report Pipe Slope Drains To minimize the potential for erosion on the 3H:1V sideslopes of the final cover system, slope drains and diversion dikes will be installed on the capped portions of the landfill. Both pipes and dikes will be adequate to handle the anticipated 25-year storm peak flows. Calculations for the slope drains and associated diversion dikes are provided in Appendix I of the Design Report Sediment Basins As noted above, seven sediment basins will be used to control stormwater. Six of the basins (SB1 through SB6) will be designed in accordance with Virginia Erosion and Sediment Control Handbook standards. The basins have been sized to handle the 25-year, 24-hour storm as well as pass the 100-year storm event. Supporting calculations are provided in Appendix I of the Design Report. The design provided for SB1 is discussed in the Initial Design Report. That design for SB1 still provides for adequate capacity and has not been modified relative to the Quarry Cell. The designs for SB2 and SB3 are revisions to original designs as discussed in the Initial Design Report as they pertain to stormwater management in and around Cells 26 and 27. The basins designs were revised to provide adequate capacity for the new, larger drainage areas. Unlike the other basins, Sediment basin 7 (SB7) will be used as a sediment basin as well as a discharge point for groundwater from the gradient control system. Also, SB7 is located in the old quarry pit and, therefore, gravity discharge of water from the basin is not feasible. A pump station will be installed in SB7 with adequate capacity to remove the groundwater inflow as well as stormwater that is conveyed to the basin. Water will be pumped to a hydrodynamic separator (for primary sedimentation) and eventually pumped to Swift Creek via a gravity drained pipe. Supporting calculations for SB7 are provided in Appendix I of the Design Report. An emergency generator will be installed to provide back-up power to the SB7 pump station as a contingency in the event of an extended power outage. 4.2 VPDES PERMIT The Facility currently has a General VPDES Permit that is summarized below. SBI will work with VDEQ to determine the VPDES Permit that best fits the Facility in the future Background The current VPDES Permit under the Clean Water Act, as well as Virginia Pollutant Discharge Elimination System and the Virginia State Water Control Law, enables stormwater discharges associated with industrial activity. The Permit s effective date is July 1, 2014, and its expiration date is June 30, Shoosmith Sanitary Landfill 19 8/27/15

53 Liquids Management Plan ATTACHMENT Effluent Limits, Monitoring, and Special Conditions Monitoring and Corrective Actions A quarterly visual examination for non-exempted discharges from each outfall must be performed. Records of reports produced as part of the quarterly visual monitoring routine should be maintained on-site with the Stormwater Pollution Prevention Plan (SWPPP). Benchmark monitoring for Total Suspended Solids (TSS) will also be performed on a semi-annual basis unless the Facility is exempted. This includes compliance monitoring required for stormwater effluent limitation guidelines outlined in 40 CFR Part 445 A and B, as well as monitoring for discharge into an impaired water with or without an approved TMDL waste load allocation. Samples should be taken during the initial 30 minutes of discharge, and if not practical, during the initial 3 hours of discharge as long as the delay is justified and explained. This information, as well as storm event data, locations of the outfalls, drainage areas of the outfalls, and any identical outfall should be submitted with the Discharge Monitoring Report (DMR) and maintained with the SWPP. Corrective actions should be taken within 60 days of any exceedance if required. The SWPPP may also require modification within 30 days Special Conditions Non-stormwater discharges from sources such as fire hydrants and potable water line flushings are authorized by the Permit. There should be no discharge of materials such as waste, garbage, and other floating debris other than in trace amounts. Other special conditions include releases of hazardous substances or oil in reportable quantities, co-located industry, and discharges to waters subject to TMDL waste load allocations. Stormwater outfalls may be added or deleted free after proper notification and update of the SWPP. Additional conditions may apply including water quality protection, anti-degradation requirements, sewer discharge, and termination of permit coverage Conditions Applicable to All VPDES Permits Conditions which apply universally to all VPDES Permits include monitoring requirements, recordkeeping requirements, reporting requirements, compliance reports, reports of unauthorized or extraordinary discharges, notice of planned changes, and other requirements Stormwater Pollution Prevention Plan The Facility will develop and implement a SWPPP to document the selection, design, and installation of control measures, including BMPs, to eliminate or reduce the pollutants in all stormwater discharges. The plan will contain a description of: the pollution prevention team, the site, potential pollution sources, stormwater controls, and routine facility inspections. All control measures identified in the SWPPP will be maintained in effective operating condition and a maintenance schedule will be included in the SWPPP. The site will perform an annual comprehensive site compliance evaluation to ensure compliance with the SWPPP. An updated and signed SWPPP should be maintained at the site at all times. Shoosmith Sanitary Landfill 20 8/27/15

54 Liquids Management Plan ATTACHMENT Landfill-Specific Requirements The Facility is subject to additional landfill-specific requirements of the general permit. Nonstormwater liquids such as leachate, gas collection condensate, contaminated groundwater, and equipment washwater may not be discharged under the permit. The SWPPP is also required to address landfill-specific pollutants. END OF LIQUIDS MANAGEMENT PLAN Shoosmith Sanitary Landfill 21 8/27/15

55 ATTACHMENT 1

56 ATTACHMENT 1 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT Shoosmith Sanitary Landfill Quarry Permit Hydrostatic Pressure on Waste CALCULATED BY CHECKED BY CJW RHI DATE DATE 8/27/2015 8/27/2015 Hydrostatic Forces at Bottom of Waste Depth 10 Feet of MSW and 30 Feet of Head Passive Earth Pressure Conditions Passive Earth Pressure at Depth Pp = Kp * ϒ W * H F Pp = 2,205 lbs/ft = Passive Earth Pressure Pp = 3.4 * 65 lbs/ft³ * 10 ft Kp = 3.4 = Coefficeint of Passive Earth Pressure Pp = 3.4 * 650 lbs/ft² ϒ W = 65 lbs/ft³ = Unit Weight of Waste Pp = 2,205 lbs/ft² H F = 10 ft = Height of Waste φ = 33 = Friction Angle of Waste Kp = ( 1 + sin ( φ ) )/( 1 - sin ( φ ) ) Kp = ( 1 + sin ( 33 ) )/( 1 - sin ( 33 ) ) Kp = ( )/( ) Kp = ( 1.5 )/( 0.5 ) Kp = 3.4 Hydrostatic Pressure P H = ϒ H * H H P H = 1,872 lbs/ft = Hydrostatic Pressure P H = 62.4 lbs/ft³ * 30 ft ϒ H = 62.4 lbs/ft³ = Unit Weight of Water P H = lbs/ft² H H = 30 ft = Height of Water FS = Pp / P H FS = 2,205 lbs/ft / 1,872 lbs/ft FS = 1.2 Ok - Factor of safety of 1.1 or greater is considered acceptable given that the proposed scenario represents and extreme condition and is not likely to occur. 1) Friction angle of waste is assumed to be 33 Degrees, which is consistent with the value used in the Design Report. 2) Cohesion has been ignored for the purpose of this calculation to provide a conservative estimate. 3) A vertical wall is assumed for the purpose of this calculation and vertical compent of the waste weight is not considered for a conservative estimate.

57 77 77 SCS ENGINEERS STEARNS, CONRAD AND SCHMIDT CONSULTING ENGINEERS, INC MIDLOTHIAN TPKE #305 - MIDLOTHIAN, VA PH. (804) FAX. (804) SIDESLOPE RISER PIPE SHOOSMITH SANITARY LANDFILL COMPOUND DETAILS SHOOSMITH BROS., INC LEWIS ROAD CHESTER, VA QUARRY WASTE DISPOSAL UNIT SHOOSMITH SANITARY LANDFILL ATTACHMENT 1

58 ATTACHMENT 2 Environmental Consultants Midlothian Turnpike Suite 305 FAX Midlothian, VA August 23, 2015 File No Mr. Michael G. Williams, PG Associate Senior Consultant Golder Associates Inc West Laburnum Avenue Suite 200 Richmond, VA Subject: Case #97SN0206 Response to Golder s Comments on Solid Waste Permit Technical Review 8/12/15 Draft Shoosmith Sanitary Landfill (Solid Waste Permit No. 587) Chester, Virginia Dear Mr. Williams: Thank you for the opportunity to respond to the draft technical review prepared by Golder and provided by Chesterfield County on August 13, We are pleased to have the opportunity to provide additional information and clarifications about the proposed design for Cell 28, also known as the quarry cell. Background The Shoosmith landfill has been in operation since In 1997, Shoosmith applied to amend its conditional use permit ( CUP ) for an expansion. As part of that CUP application, additional land was added to the landfill operation (including the quarry area), and additional capacity was created as a result. The amended CUP was approved on May 28, In 1998, Shoosmith applied for Article VII (siting) and Article VIII (waste disposal) approval from the County, which was received on January 27, The siting approval was issued for the entirety of the site, including the quarry area. In approving the siting, Chesterfield County determined that the proposed facility poses no substantial present or potential danger to the health, safety or welfare of any person and that the proposed facility poses no substantial present or potential danger to the environment. County Code The Article VIII approval issued in 1999 included all areas of the landfill except the quarry cell. At the County s request, Shoosmith applied for Article VIII approval for the quarry cell on July 28, The County will act on this application by October 26, 2015; if no formal action is taken, it will be deemed approved on that date. Also in 1999, the Virginia Department of Environmental Quality modified the solid waste disposal permit for the facility to encompass the entirety of the new land, including the quarry area. That modification approved the new capacity for the landfill, which included the capacity

59 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 2 of the quarry cell. The County reviewed the application, and, on February 1, 1999, signed a certification that the landfill expansion, including the quarry area, met all County requirements for siting and for operation. Thus, the County approved the location and operation of the quarry area as a future disposal site. DEQ issued a permit on May 20, 1999 approving the location and operation of the quarry area as a landfill cell. As part of its approval, DEQ determined that the facility posed no substantial present or potential danger to human health or the environment. See DEQ correspondence dated May 20, Because the CUP included a condition that a solid waste permit amendment for the quarry cell could not be submitted until at least 10 years after the approval of the CUP, the design specifications associated with the quarry cell were not submitted to DEQ until October At that time, Shoosmith filed an application with the DEQ to amend the Part B permit for the landfill to add in the design specifications for that cell. The application was discussed with County representatives as well as community members at Shoosmith / Community Outreach Group meetings in DEQ deemed Shoosmith s Part B amendment application complete on December 18, In reviewing the technical merits of Shoosmith s Part B amendment application, DEQ determined that the application was technically adequate and in full compliance with all Virginia solid waste regulations, and thus has issued a draft permit. 9 VAC DEQ s draft permit is currently out for public comment on the technical aspects of the operation of the quarry site. Permitting Process The Permit Amendment for the Quarry Waste Disposal Unit will incorporate the engineering design of this cell into the Facility s Permit. The permit describes how the facility will meet the requirements of 9VAC As is typical in landfill permitting, the application may include a range of options for meeting the regulatory requirements. Details regarding construction-level design elements and specifications are not included. Likewise, the level of detail for the components and features of the environmental control aspects for the Quarry Cell may be expanded in future design and constructions drawings and will incorporate the appropriate field conditions, operating methods, and technology that are appropriate at that time. The manner in which the Landfill will implement the design and any subsequent construction plans will be addressed by an update of the Facility s existing Operations Manual in accordance with 9VAC DEQ oversees the implementation of the cell design, both through on-site inspections and by requiring periodic reports on construction progress and updates to the appropriate documentation and, ultimately, issues a Certificate-to-Operate (CTO) prior to initial waste placement and commencement of operations in the cell. Quarry Cell Design The proposed design of the Quarry Waste Disposal Unit is not atypical.. The Quarry Waste Disposal Unit is subject to the same regulations as any other solid waste disposal facility. The

60 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 3 Quarry Waste Disposal Unit is required to have the same permits and provide the same environmental protection expected from any other solid waste disposal facility. It is not unique in that the base grades extend into bedrock, since there are other cells at this Facility as well as other landfills that require excavation to bedrock. It is not accepting any new waste that is different from the existing waste disposal units on the site. The same methods of leachate collection, groundwater collection, and gas collection that are successfully used at the existing cells at this Facility as well as in other solid waste disposal facilities, have been adapted for use in the Quarry Waste Disposal Unit. The proposed liner systems will meet or exceed the requirements that other solid waste disposal facilities are required to meet. Landfills are built in a variety of geographic locations across the country in many different environmental conditions that require some adaptation similar to the approach that has been taken with the Quarry Waste Disposal Unit. From a regulatory perspective, the Quarry Waste Disposal Unit will be held to the same standards as any other solid waste disposal facilities. Shoosmith Bros., Inc. (SBI) and their engineering consultant SCS Engineers (SCS) are available to meet with representatives from Golder and Chesterfield County to discuss the responses presented herein. Also, we extend an invitation for representatives from Golder and Chesterfield County to visit the Facility and conduct a site reconnaissance into the quarry pit during the week of August 23, 2015 to observe existing field conditions and discuss elements of the Solid Waste Permit Amendment documentation. Listed below, as they appeared in Golder s Technical Review draft document, dated 8/12/15, are Golder s comments (in italics), each followed by a corresponding response. TECHNICAL REVIEW GENERAL COMMENTS Comment 1: The overall concept for the landfill requires that three active systems (groundwater control, leachate collection, and gas collection) be operational for significant periods of time and with minimum down-time to prevent non-compliance with various Virginia regulatory requirements and/or engineering failure of key components of the landfill systems. Also many of the landfill components are unique due to geometry of the side walls, the inflow of groundwater and overall depth. Because of the uniqueness of the design features, these designs need to be developed in sufficient detail so that adequate potential failure analysis can be performed. Of particular concern is the gas collection system as this system design is not as well developed as the groundwater control or leachate collection system. While this is typical for landfills installing vertical wells after final grades are reached, this gas system must be fully vetted and designed as a part of the permit application because its installation will begin early in the development of Cell 28 with the placement of horizontal collectors.

61 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 4 The comments below are provided given the critical and unique nature of some of the design features to help provide better confidence that critical design issues have been identified and addressed. These comments do not indicate that the existing design will fail, unless specifically stated as our opinion for a specific component. Unless specifically noted, the request is being made for further analysis to evaluate potential failure. A) Make sure all calculations are checked and reviewed. Several critical calculations from subcontractors have not been checked (example: Landmark vertical wall design). Additionally, several inconsistencies were identified within and between design calculations. For example, several unit weights of MSW were utilized throughout the calculations. In addition, the equivalence demonstration of the proposed liner systems do not correctly reflect the proposed liner system components presented in the Permit Drawings and Design Report. It is acknowledged that while these inconsistencies may not affect the overall conclusions of the design calculations, the design assumptions should be consistent throughout the application. Response 1A: SCS and SBI verified that calculations presented in the Solid Waste Permit Amendment documentation, including the Design Report and Leachate Management Plan, were reviewed and checked. The different MSW unit weights used in the design calculations that were developed over an extended period of time reflect different levels of conservatism assumed by the designer and are not considered inconsistencies. For example, the waste density values used in the lifespan computations bracket the range between dense waste (Scenario A at 1,800 pcy) and moderately dense waste (Scenario B at 1,400 pcy), leading to a lifespan range between 15 and 19 years. This enables the life expectancy projections to provide a range of possible lifespans depending on waste composition, compaction characteristics and on-going waste settlement, all of which may change with time. For the design calculations pertaining to the Quarry Cell, including slope stability, waste settlement, pipe strength, bearing capacity and the vertical wall support section, the unit weight values applied range between 65 pcf (1,755 pcy) and 77 pcf (2,080 pcy), which are all conservatively higher than has actually been calculated from recent airspace analyses for the existing waste disposal units where waste thicknesses are approximately 200 feet. These values are well within the accuracy of waste density calculations and anticipate the waste thickness proposed for the Quarry Cell. Recent estimates of MSW density, based on airspace utilization, yielded values of 57 pcf (1,539 pcy) to 60 pcf (1,620 pcy) for the period of 2008 to On this basis, we believe the MSW density values used in various calculations are appropriate and consistently conservative. As the comment recognizes, applying the appropriate, most conservative unit weights as was done here does not affect the overall conclusions of the design calculations, which demonstrate that the quarry design is technically sound and protective of human health and the environment. Based on discussions with the County and Golder, SBI and SCS understand the statement in this comment regarding equivalence demonstration of the proposed liner system is specifically directed toward the thickness of the 40-mil FML component of the Alternate Bottom Liner

62 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 5 (ABL) System as cited in Appendix F. This citation contained a typographical error, which will be corrected. Please see Response B) The design should include reasonable measures to reduce the amount of water reaching the groundwater control system during the early stages of filling. Specifically, this would include intercepting surface water run-on to the maximum extent possible before it reaches the groundwater control system. This would lengthen the amount of time that the groundwater pumping system could be down prior to causing the unacceptable buildup of hydraulic pressures under the bottom liner. Response 1B: The stormwater run-on control system is generally described in Section 2.5 of the Design Report as consisting of existing stormwater features associated with the other waste disposal units (e.g. rim cells - Cells 25, 26 and 27) and new stormwater conveyance channels and sediment basins as shown on Sheet 70 of the Permit Design Drawings. Additionally, the existing berm that is positioned at the rim of the quarry pit will remain in place upon termination of commercial quarry operations, and be improved or enhanced prior to liner system construction activities where appropriate, to divert stormwater from the areas surrounding the quarry pit into conveyance features on the rim. During the stages of bottom and sidewall liner system construction, as well as during subsequent waste placement operations, stormwater will be intercepted along the upper sidewall benches and upper portions of the access ramp, utilizing berms, channels, flat panel drain pipes, or other suitable features. This will reduce the quantities of stormwater that would have the potential to be introduced into the backfill behind the VLSS or the aggregate subbase and, ultimately, require handling by the gradient control system infrastructure. These berms, channels, pipes, and other diversion features will direct stormwater to retention/detention zones within the quarry pit where it can be stored and/or pumped. In addition, during and after construction of the sidewall liner system, measures to cover the exposed top portion of the backfill behind the VLSS to reduce stormwater infiltration into the gradient control system will be implemented. Methods may include, but are not limited to, use of tarps, geomembrane sheeting, or soil cover to promote drainage away from exposed backfill. The Solid Waste Permit Amendment documentation does not include details depicting the alignment, configuration, dimensions, and materials of construction for such interim run-on control features, as described above, because such level of detail is not typically included at this permit documentation stage. Most of the stormwater that falls within the Quarry Cell will be handled by features described in section 2.5 or handled by stormwater control features that are progressively located within the waste filling area. The average stormwater flow from the remaining areas, which may potentially be handled by the gradient control system, represents approximately 12 percent of the peak monthly groundwater inflow used to size the gradient control pumps discussed in Section II.2.e of the Gradient Control Plan in Appendix H of the Design Report. This is within the factor-of-safety used to size the pumps and additional capacity can be created if necessary by adding pumps in the sideslope riser pipes, as well as using the gradient control collection pipe

63 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 6 cleanouts for additional pumping. Thus, the design contemplates not only minimizing run-on reaching the groundwater control system during the early stages of filling but also management of heavy flows caused by an extreme weather event so that there will not be a buildup of hydraulic pressure under the bottom liner. C) Provide additional details and technical support on the gas collection design, particularly the following: a. The connection of horizontal collectors to vertical risers and potential failure of these connections due to differential movement of risers and laterals. Response 1Ca: The Permit Design Drawings in Attachment III depict details on the locations, configuration, dimensions, materials of construction, and other aspects related to construction of the landfill gas collection system in the Quarry Cell. Appendix D of the Landfill Gas Management Plan in Attachment IX presents the narrative discussion regarding well and collector spacing and orientation, header pipe sizing, condensate production, and other system features. In addition to being reviewed by VDEQ s Waste Division, the gas collection system is also reviewed by the VDEQ Air Division. Thus, prior to constructing the landfill gas (LFG) collection system in the Quarry Cell, the Facility will be required to update the existing NSPS LFG Collection and Control System Design Plan (Design Plan) in accordance with 40 CFR and the Facility s existing air quality permits. The updated Design Plan will be prepared and certified by a professional engineer licensed in Virginia and this Plan will be submitted to the VDEQ Division of Air Quality for approval prior to the installation of the LFG system components. During the development of the Design Plan and subsequent construction documentation, the specific configuration, dimensions, materials of construction, and other design parameters for the connection of the horizontal collector/vertical riser will be finalized. For purposes of development of the Solid Waste Permit Amendment documentation for the LFG collection system in the Quarry Cell, the impact of differential settlement was assessed. Several conceptual scenarios for accomplishing this connection at the horizontal collector/vertical riser have been considered. One approach for this connection is to use a 12-inch wye fitting with a straight section of pipe on the wye end pointing downward to serve as a slip joint. The end of the 6-inch horizontal connector pipe would slip upward into the 12-inch-diameter section of pipe. Note that this connection does not need to be a movement limiting welded connection and would allow the pipes to move while remaining connected to adapt to differential settlement. Another potential approach is to utilize high-strength flexible piping, similar to the materials typically installed at abovegrade wellheads, with sufficient excess material to anticipate settlement of the horizontal collector. b. Provide technical support for using Standard Dimension Ratio (SDR) 17 High Density Polyethylene (HDPE) for lateral collectors. SDR-11 is recommended in trenches for ground water and leachate collection and these pipes will be in trenches on a firm base. The trench recommended for the gas collectors is likely to be less effective in providing support since it will be cut into waste, which will not provide for a firm backfill around the pipe. The use of tire shreds is not advised for backfill since they will be compressible.

64 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 7 Response 1Cb: As described above, the landfill gas (LFG) collection system is regulated by both the air and waste divisions of VDEQ. Prior to constructing the landfill gas (LFG) collection system in the Quarry Cell, the Facility will be required to update the existing NSPS LFG Collection and Control System Design Plan (Design Plan) in accordance with 40 CFR and the Facility s existing air quality permits. The updated Design Plan will be prepared and certified by a professional engineer licensed in Virginia and this Plan will be submitted to the VDEQ Division of Air Quality for approval prior to the installation of the LFG system components. During the development of the Design Plan and subsequent construction documentation, the specific configuration, dimensions, materials of construction, pipe wall thickness, size, and spacing and other design parameters for the LFG horizontal collectors shown on the Permit Design Drawings will be re-evaluated and modified, if warranted. For purposes of responding to this comment, SCS re-evaluated the pipe wall thickness for the LFG horizontal collectors. Based on this evaluation, it is concluded that LFG horizontal collectors with less than 100 feet of waste shall be SDR-17 or lower SDR (which correlates to a thicker pipe wall). The LFG horizontal collectors installed with greater than 100 feet of waste to be placed above them shall be SDR-11 or lower SDR. Also, the Facility will avoid the use of tire shreds as backfill for the LFG horizontal collectors in the Quarry Cell. SBI and SCS will request that the VDEQ clarify the specified SDR value and omit reference to tire shreds as an alternate backfill material on page 5 of Appendix D of the LFG Management Plan as well as on Sheet 68 of the Permit Design Drawings. c. The potential for failure of individual horizontal collectors due to condensate accumulation, pipe crushing, higher temperatures, and differential settlement. What measures can be taken to detect failed collection laterals and remedy (provide gas collection to these area) them. Response 1Cc: The potential for individual horizontal collectors to become ineffective as LFG extraction components, or become non-functional due to a variety of reasons, including liquid blockages, pipe crushing, elevated temperatures, and impact of differential settlement, was considered and assessed. Several provisions were incorporated in the proposed design to reduce the likelihood of such circumstances: To reduce the potential for condensate accumulation/liquid blockages within the horizontal collector, the horizontal collectors are typically installed in the landfill surface at a slope of 3 to 5 percent (refer to Drawings 56A through 57). The horizontal collector trench provides substantial coarse aggregate backfill surrounding the perforated pipe. In the event the pipe is crushed within the perforated section, the gravel backfill within the collector s trench will continue to serve as a conduit for LFG accumulation and collection. In some cases, LFG will be collected from both ends of the horizontal collector, thereby providing some redundancy.

65 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 8 The design includes an optional geocomposite drainage net, specified as the GSE Biodrain HP, to be installed in intimate contact with the coarse aggregate for the horizontal collector trench, which is intended to enhance drainage and supplement LFG extraction and increase the zone-of-influence exerted by the horizontal collectors. The historical practice at the Landfill has been to install horizontal collectors in conjunction with waste placement operations and then to install vertical LFG extraction wells to enhance LFG recovery upon achieving sufficient waste depths. SBI anticipates continuing this historical practice once filling operations move into the Quarry Cell. Several measures to identify ineffective or non-functional LFG extraction components (horizontal or vertical), as well as portions of the LFG collection piping that are not distributing vacuum to the LFG extraction components, are as follows: Routine surface emissions monitoring and odor monitoring performed at the Facility will provide a demonstration of LFG collection system efficiency and performance. The vertical collectors will be equipped with wellheads that allow the measurement of flow and the absence of flow would signal that the collector may be ineffective or nonfunctional. Contingency action items to enhance LFG extraction from portions of the waste mass that demonstrate insufficient LFG collection are as follows: In cases where the collectors have a wellhead at each end, a corrective action would be to increase the vacuum on other end of the collector. In the event the non-functional collector is not equipped with a second wellhead, the collector would be abandoned in accordance with the Facility s Design Plan and LFG generated in the area of the decommissioned collector would be captured by adjacent collectors. The waste placement operations required to achieve waste depths of 100 to 200 feet in the Quarry Cell will require approximately 10 years or so. This extended timeframe will provide an opportunity to evaluate the performance of the horizontal collectors. If areas that demonstrate insufficient LFG extraction are identified, the Facility will install vertical extraction wells, which can be drilled to depths of 150 feet or more. As discussed in Section 3.0 of Appendix D of the LFG Management Plan, the wellheads to provide control to vertical extraction wells may be extended up as additional waste lifts are placed, or they may be routed to the nearest sidewall bench where a connection to a vertical collector or riser pipe that serves as a manifold for the header piping that transports LFG along the sidewall bench can be accomplished. The installation of vertical gravel-filled caissons could be implemented along the horizontal collectors to aid in dewatering the collectors and increase the zone-ofinfluence exerted by the horizontal collectors.

66 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 9 The permeability of the 18-inch cushion layer that will be placed between the waste and the sidewall liner system is unspecified. The Facility could potentially opt to place a manufactured sand material or other high permeability product to serve as a LFG collection layer that would essentially form a blanket surrounding the waste mass to intercept LFG in the vicinity of the sidewalls. Introduction of an applied vacuum at the leading edge of this layer via a network of perforated pipes at the top of the landfill would create a continuous LFG extraction layer. D) The Design Report discusses a third option for the VZSS and the locations of the Mechanically Stabilized Earthen (MSE) wall are shown on the Permit Drawings; however, design details for the MSE wall and its compatibility and connection with the proposed liner systems are not provided in the Permit Drawings. Response 1D: As described in Note 2 of Detail 2 on Drawing 75A, as well as in various sections of the Design Report, the sidewall vertical liner support system (VLSS) includes options for a MSE wall or a compacted soil berm constructed in a conventional fashion for purposes of deploying the components of the Alternate Sidewall Liner System (Soil). We interpret Golder s use of VZSS to refer to the VLSS. The backfill behind the VLSS will be placed and function similarly under either option. The design details for the MSE unit, consisting of geogrid elements (refer to Specification Section 13521, GEOGRID) that will be placed within the backfill and the compacted structural fill, are presented in the Design Report and Specifications. Development of construction-level details depicting the connections with the proposed liner systems for adjacent elements (bottom of quarry pit, sidewall vertical, and/or sidewall bench) are beyond the scope of permit-level documentation required by the regulatory permitting process instituted by VDEQ. The level of detail for the components and features of the MSE wall for the Quarry Cell may be expanded in future design and construction documents. Examples of additional permit-level design details for the existing MSE berm at the Facility can be found in the Facility s existing Solid Waste Permit under Modification No. 14. E) Provide details for how the recovery of groundwater and leachate from these systems will be achieved for the different waste stages prior to waste reaching the rim of the quarry. Response 1E: The Permit Design Drawings in Attachment III depict details on the locations, configuration, dimensions, materials of construction, and other aspects related to construction of the gradient control and leachate collection systems. The Design Report in Attachment IV and the Leachate Management Plan in Attachment VIII present the calculations regarding sizing of aggregate sumps, pipes, pumps, tanks, and other system features, as well as a narrative description of the operational procedures. Based on discussions with the County and Golder, SBI and SCS understand this comment is specifically directed toward the construction, access, and operation of the Leachate/Gradient Control Sideslope Riser Compound, which is described on Page 15 of the Design Report and depicted on the Drawings. Accordingly, refer to Response which outlines the plan for the initial phases of construction of the riser compound structure and the associated riser contingency access vault.

67 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 10 The design of the gradient control and leachate collection systems incorporates the potential to utilize the gradient control collection pipe cleanouts and the leachate collection pipe cleanouts for additional pumping locations using portable pumps, if supplemental recovery actions were warranted as a contingency plan during an extreme weather event or other scenario. Also, mezzanine level gradient control collection pipes and mezzanine leachate collection pipes will be installed behind and interior to the sidewall VLSS at select sidewall bench elevations. These features provide direct access to gradient control water and leachate at higher elevations than the bottom sumps for recovery and management activities, if warranted as a contingency plan during an extreme weather event or other scenario. F) The active leachate system will be depended upon to remove leachate from multiple sources for extended periods of time, some of which are not typical for MSW landfills. These include: Response 1F: The sources of liquids that will be managed by the Quarry Cell leachate collection system are typical for MSW landfills. The leachate collection system infrastructure has been designed to anticipate liquid quantities from these sources. a. Condensate from the gas system collector laterals; Response 1Fa: Management of liquids attributed to landfill gas condensate by the leachate collection system is typical for nearly all MSW landfills. Based on over 25 years of leachate system and landfill gas condensate management operational experience at this Facility, it is anticipated that the volume of landfill gas condensate managed in the Quarry Cell leachate collection system will be inconsequential compared to the volume of leachate collected within the Quarry Cell. The leachate collection system infrastructure is designed to accommodate liquid quantities from landfill gas condensate. b. Inflow of groundwater through leaks in the liner system; Response 1Fb: Upon termination of active pumping from the gradient control system, there is a remote possibility of groundwater infiltration into the leachate collection system through leaks if any develop in the liner system. However, it is anticipated that the volume of groundwater managed in the Quarry Cell leachate collection system will be inconsequential compared to the volume of leachate collected within the Quarry Cell. c. Leachate from the recirculation system; Response 1Fc: Management of leachate that is recirculated back into the waste mass is a typical operational scenario for many MSW landfills and the leachate quantities attributed to leachate recirculation that will be managed by the Quarry Cell leachate collection system is included in the analysis for scenarios with the prescriptive Subtitle D bottom liner system, which is addressed in Section of the Leachate Management Plan. d. Infiltration through the cover, particularly the steeper 3H:1V slopes that do not contain a flexible membrane liner; and

68 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 11 Response 1Fd: Management of leachate quantities attributed to stormwater infiltration through the alternate final cover system that is permitted on the 3H:1V is a typical operational procedure for the Facility since the final cover design for the Quarry Cell is consistent with that used in the other waste disposal units at the Landfill. Upon installation of the final cap, the quantity of stormwater infiltration from these areas is anticipated to be relatively small considering the 3H:1V slopes promote runoff, are capped with a low-permeability soil layer, and have a geocomposite drainage net (GDN) component in the final cover system. The GDN will convey stormwater that infiltrates through the vegetative support layer to stormwater management features, thereby limiting hydraulic head over the low-permeability soil layer. e. Normal leachate generation from precipitation during construction and waste filling. Response 1Fe: HELP model computations presented in the Leachate Management Plan were performed for different phases of waste filling, for scenarios with waste depths of 10 feet, 30 feet, 100 feet and 300 feet. The HELP model accounts for precipitation in each of these scenarios. Because of this, leachate quantities could actually increase over time during operations and the system may have to pump well beyond the typical 30-year post-closure time frame. Given the critical nature of this system, the components of the system should be viewed as requiring extended life with appropriate design considerations included as needed to demonstrate the systems will function as desired for the life of the landfill. This also illustrates the importance of including construction of this system in the Construction Quality Assurance (CQA) Plan. Response 1F(a-e): The experience at this Facility is that the greatest leachate generation rate typically occurs when the waste depth in a cell is shallow and decreases as the waste depths increase. Nonetheless, the system has been designed to manage additional leachate quantities, if these are experienced. The amount of leachate generation for a typical landfill in the Mid- Atlantic region is more dependent on the amount of rainfall and the permeability of the cover soil than on the thickness of the waste. Leachate generation estimates (Leachate Management Plan, Appendix B) indicate that the quantity of leachate decreases as landfill height increases. This is expected due to the increase in absorption of infiltrated precipitation by the waste, rather than passing through the waste mass. Leachate generation is expected to decrease under areas that have been capped, because the final cover system will minimize infiltration. Because the closure cap will be completed at the start of the post-closure care period, the landfill s leachate generation rate should further decrease during the post-closure time frame. It is acknowledged that the leachate management system may have to function beyond the 30- year minimum post-closure care (PCC) period, which is a consideration for any landfill. The leachate management system has been designed with long-term operation and maintenance in mind, and redundancy is provided. The length of the PCC period may be decreased or increased by VDEQ as authorized under , and 9 VAC C. Procedures for terminating Post-Closure Care are provided in VDEQ Waste Guidance Memo : Post-Closure Care Termination.

69 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page CONDITIONAL USE PERMIT REVIEW Golder understands that County staff are performing a review of the 29 conditions (three imposed and 26 proffered) contained in the May 28, 1997, CUP (CUP #97SN0206) to ensure that required conditions have been met or are scheduled to be met. Golder has also reviewed the conditions in the CUP, and based on our review, offer the following observations: 1.1 PROFFERED CONDITION NO. 13 Comment: The phrasing in the draft permit (Module II) is inconsistent with the CUP phrasing. Golder recommends that the phrasing in the draft module be standardized to match that in the CUP. Specifically, draft Permit Condition II.A.1 should be modified to indicate that the facility operator will restrict waste delivery operations between the hours of 12:00 AM and 06:00 AM to only trucks owned and operated by Shoosmith Brothers, Inc. with no more than 12 trucks allowed during the 12:00 AM and 06:00 AM timeframe (i.e., number of trucks shall not exceed an average of two trucks per hour). Response: The Landfill operation is subject to the requirements of its VDEQ solid waste permit, all other permits issued by VDEQ, as well as the conditions of the CUP and any other regulatory approvals issued by Chesterfield County. SBI must comply with all of the CUP conditions, even if they are not directly reflected in the solid waste permit. The Facility will change the language in the existing Operations Manual to reflect the language in the CUP condition and SBI and SCS will request that the VDEQ modify the language in the Draft Permit Module accordingly. 1.2 PROFFERED CONDITION NO. 14 Comment: The phrasing in the draft permit (Module II) is inconsistent with the CUP phrasing. Golder recommends that the phrasing in the draft module be standardized to match that in the CUP. Specifically, draft Permit Condition II.B.2 should be modified to indicate that the facility operator will not accept stock farm animal carcasses for disposal in the waste management area. Response: The Landfill operation is subject to the requirements of its VDEQ solid waste permit, all other permits issued by VDEQ, as well as the conditions of the CUP and any other regulatory approvals issued by Chesterfield County. SBI must comply with all of the CUP conditions, even if they are not directly reflected in the solid waste permit. The Facility will change the language in the existing Operations Manual to reflect the language in the CUP condition and SBI and SCS will request that the VDEQ modify the language in the Draft Permit Module accordingly. 1.3 PROFFERED CONDITION NO. 25 Comment: The condition required the facility owner to file restrictive covenants in a form or forms acceptable to the County Attorney that satisfy the description as stated in Exhibit C of the CUP. The May 20, 1999, DEQ approval letter for Permit No. 587 is labeled as Final Permit Number 587. At this time, it is unclear whether the restrictive covenants in Exhibit C of the CUP have been filed to the satisfaction of the County Attorney.

70 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 13 Response: Restrictive covenant language was reviewed and approved by the County Attorney s office in That language has not been recorded yet because a final permit that includes the technical details for development of the quarry area has not been issued by VDEQ. SBI will record the language upon VDEQ s issuance of the final permit. If the County would like the restrictive covenants to be filed before a final permit is issued, SBI would be willing to consider this. 2.0 PART A APPROVAL CONDITIONS The March 2, 1999, Part A Conditional Approval letter contained seven conditions that the Facility operator was required to meet as part of part B submittal for the landfill expansion. Golder has reviewed these conditions and based on our observations, we offer the following comments. 2.1 CONDITION 6, MARCH 2, 1999, PART A APPROVAL LETTER Comment: Condition 6 required the facility operator to submit a minimum of 3 years of monthly data for metered pumping rates and volumes from within the quarry, along with monthly precipitation and other hydrological data for the quarry to assist with the design of the Cell 28 groundwater control system. In the notes to the January 27, 1999, Board of Supervisors meeting (Item 16B), a Mr. Hale is noted as stating during dry weather, there are 28,000 gallons per day of water being pumped out of the quarry. Golder reviewed the pumping information submitted by Shoosmith Brothers, Inc. to the DEQ to meet Condition 6 (see submittal letter from Joyce Engineering dated October 29, 2009). These pumping data covered the years of 2006, 2007, 2008, and the first 3 months of A summary of the pumping information (gallons per day average for the above timeframes) is presented below: Gallons per day Year (yearly total divided by number of days) , , , ,500 As presented, the average pumping per-day rate for the 2006 to 2009 timeframe is significantly higher than the volume reported in From the report, it is not clear if this water was pumped out of the quarry as appears to be the intent of the condition, and it is not clear whether these volumes are commingled stormwater and groundwater dewatering, or a combination of stormwater, groundwater, process water, and surface water impoundment leakage. Additionally, the report does not address the source of the change observed in the average daily pumping rates between 2006 and 2009, or 1999 for that matter. In summary, it is unclear if the gradient control dewatering system for Cell 28 has been adequately designed to handle the flows

71 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 14 that appear to require management. Golder recommends that the source of the volume variations be further evaluated to ensure that the dewatering system can handle the expected flow, with any expected variance, so as to protect the liner from hydrostatic uplift. Response: We do not know the basis for Mr. Hale s comments in Mr. Hale was not affiliated with SBI or SCS. The referenced Gradient Control Plan (GCP) (Pages 1 and 2) identify the sources of inflow to the Quarry sump. Those sources are precipitation, surface run-on, pond seepage, and groundwater inflow. The gradient control system design is based on pump operational data from April 2008 and afterward, and makes a conservative inventory to account for the additional sources. The higher numbers from April 2008 and onward form the basis of the GCP, and the design is sufficient to handle those levels of flow. An additional 6-10 years of data will be collected before final design. Thus, the design can be adjusted based on this data prior to construction. 3.0 ENGINEERING DESIGN REVIEW Landfill Capacity 9VAC A Comment 1: Adequately addressed. Response 1: No response required Vehicular And Public Access Controls 9VAC B Comment 1: Unclear what type of safety measures/access control current exists or is proposed along the top of the quarry high wall. Response 1: The Initial Design Report, which is incorporated into the Facility s current Solid Waste Permit, addresses site access in Section 2 on page 6, which states: Access to the landfill is controlled by Shoosmith Bros, Inc., which is maintained by a combination of perimeter fencing, natural barriers, and a wide lockable gate across the entrances off Route 10 and Lewis Road. The gate to the landfill will be closed and locked during non-operating hours to prevent entry and illegal disposal of wastes. There are no uncontrolled vehicle access points to the landfill. Existing service and access roads within the landfill facility are shown on the Permit Design Drawings. The perimeter access road base course shall consist of a suitable subbase and stone for the wearing course. The road will be cross-sloped to promote positive drainage. The road will be maintained to provide all-weather access for vehicles using the landfill. Proper maintenance shall include removal of deposited mud, snow removal, and regrading and recompacting existing stone.

72 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 15 The Quarry Cell will be within the barriers outlined in the Initial Design Report for the Landfill. This language adequately addresses requirements of 9VAC B which states: All facilities shall be surrounded on all sides by natural barriers, fencing, or an equivalent means of controlling vehicular and public access and preventing illegal disposal. All access will be limited by gates, and such gates shall be securable and equipped with locks, except, in the case of industrial disposal sites where the solid waste disposal landfill is on site of the industrial facility where access is limited. The roadway access limitations discussed in the Initial Design Report also prevent access to the quarry in accordance with the requirement the quarry is currently subject to under 4VAC which states: Access to unattended mine roads or openings shall be restricted by use of gates, doors, or fences and warning signs shall be posted. In effect the same controls that limit public access to the landfill site as a whole, also function to prevent access to the Quarry Cell. While the Quarry Cell is unique in many aspects, it still must be integrated into the existing landfill cells. To facilitate this integration, it is more practical to limit public access to the facility as a whole than to provide separate access control measures for each individual cell. With public access adequately addressed in the current Solid Waste Permit, the Design Report for the Quarry Cell focused on controlling traffic that is accessing the Landfill, but not necessarily the Quarry Cell. Traffic control is addressed in section Site Access which states: Access to the landfill is discussed in the Initial Design Report. Site access issues and protocols specific to the Quarry Cell are discussed in the Operations Manual for the Quarry Waste Disposal Unit. Vehicles transporting waste materials, cover soil, and construction equipment, along with personnel performing these and other duties, will require access into the Quarry Cell on a daily basis. In addition to the standard health and safety issues pertaining to normal landfill operations and waste disposal facilities, it is recognized that the Quarry Cell presents an additional safety issue for personnel and equipment due to the potential for small-scale rock falls. The Facility will, within the Operations Manual, develop specific guidelines and policies that address authorization for accessing specific locations within the Quarry Cell and will implement restricted zones to reduce the risk of injury or damage to equipment due to potential rock displacement. While waste collection and transport vehicles will need access to the staging area and working face, these vehicles and drivers will not be allowed to enter certain areas that are designated as restricted zones, which will be limited to authorized personnel only. Accordingly, traffic patterns and signage will be developed to educate landfill

73 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 16 operations personnel, construction personnel, facility staff, customers, and visitors identifying restricted areas upon entering the facility. In addition, facility staff will be trained and empowered to enforce these policies upon notification of any potential violations. Simultaneous with filling operations in Cell 28, the Facility plans to maintain some disposal capacity within Cells 22 through 27 that can be utilized to accommodate filling operations as a contingency plan in the event that access into the Quarry Cell is obstructed or becomes challenging due to weather-related natural disasters. Development of policies and procedures to govern access to the Quarry Cell and the surrounding areas following permit issuance is the normal procedure in the landfill permitting process. These access procedures would outline methods including, but not limited to, barricades, earthen berms, signage, fencing, gates, boulders, or roadway barriers to limit access during construction and operation of the Quarry Cell. Different methods of controlling access to the Quarry Cell may be used in different areas and at different phases of the Quarry Cell development. By employing a variety of methods SBI can select those methods that best accommodate the changing conditions not only as the Quarry Cell is in development, but also as the construction and filling of Cells approaches the quarry. As the filling in the Quarry Cell reaches the rim of the quarry and integration of the Quarry Cell into the existing cells begins, these methods and procedures may be adapted. The facility will update the Operations Manual to reflect the methods, procedures, and policies being used to control access to the Quarry Cell within the landfill site. Changes to the Operations Manual are periodically reviewed by VDEQ. Training for facility staff will include reviewing the most recent policies and procedures for controlling access to the Quarry Cell and methods of enforcing those policies and procedures Access Roads 9VAC C Comment 1: No access road detail provided in the Permit Drawings. Response 1: Sheets 52 through 55 of the Permit Design Drawings in Attachment III have labels designating the locations of existing and proposed access roads, all of which are, or will be, allweather roads suitable for handling the operations traffic at the Facility. Also, Sheet 75D of the Permit Drawings includes a profile of the access ramp to Cell 28. Access road cross section details were also included in the Initial Permit Design Drawings which are incorporated into the Facility s current Solid Waste Permit (refer to Sheets 37 and 133 which are attached for reference) Surface Water Runoff Comment 1: The description of the run-on control system is inadequate to evaluate whether the proposed run-on system is sufficient in mitigating run-on to the quarry. In addition the Gradient

74 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 17 Control Plan seems to indicate that the gradient control system was designed for groundwater infiltration and precipitation over the quarry area, but does not account for run-on from surrounding drainage areas. Response 1: The stormwater run-on control system is generally described in Section 2.5 of the Design Report as consisting of existing stormwater features associated with the other waste disposal units (e.g. rim cells - Cells 25, 26 and 27) and new stormwater conveyance channels and sediment basins as shown on Sheet 70 of the Permit Design Drawings. Additionally, the existing berm that is positioned at the rim of the quarry pit will remain in place upon termination of commercial quarry operations, and be improved or enhanced prior to liner system construction activities where appropriate, to divert stormwater from the areas surrounding the quarry pit into conveyance features on the rim. SCS evaluated the existing stormwater features which are shown on Sheets of the Permit Design Drawings, and are discussed in Section 5 and Appendix X of the Initial Design Report. Design of the new stormwater features are further described in Section 3.4 of the Quarry Cell Design Report, and calculations are provided in Appendix I. Perimeter channels and storm drains were designed to convey the combination of run-on flows from surrounding areas and runoff flows from the landfill surface. These flows are conveyed to sediment basins which are sized for drainage areas including the landfill and surrounding areas. During filling of the Quarry Waste Disposal Unit, rain covers will be used to impede stormwater that is stored in the interim sediment basins and other temporary detention areas from infiltrating into the waste mass, and the stormwater collected on the rain covers will be pumped to sediment basins. Page 3 of the Gradient Control Plan addresses run-on in the second paragraph under b. Precipitation/Evapotranspiration Liner Systems 9VAC J Comment 1: The alternative liner system equivalence demonstration calculations presented in Appendix G of the Design Report do not correctly model the proposed alternative bottom liner system presented in the Design Report and shown on the Permit Drawings. Additionally, the references for the assumed hydraulic conductivities of the concrete and synthetic sheet piling VZSS materials are unclear. For example, does the assumed hydraulic conductivity of concrete assume any degree of cracking/degradation? By inspection of the proposed VZSS systems, the concrete structural members will consist of pre-cast or cast-in-place panels installed between steel soldier piles or will consist of vinyl sheet piling. However, the Design Report does not address whether the concrete-i beam interface or the sheet piling interlocking will be adequately water sealed (nor is this discussed in the CQA Plan). Therefore, the equivalence demonstration of the alternate liner systems should demonstrate performance at the locations of these construction joints. Response 1: Based on discussions with the County and Golder, SBI and SCS understand the first statement of this comment is specifically directed toward the thickness of the 40-mil FML

75 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 18 component of the Alternate Bottom Liner (ABL) System. The remaining alternative liner system equivalence demonstration calculations presented in Appendix G of the Design Report do correctly model the proposed alternative bottom liner system presented in the Design Report and shown on the Permit Drawings. The ABL proposed for the Quarry Cell demonstrates superior performance and reduced infiltration compared to the prescriptive Subtitle D liner system and the prescriptive VSWMR alternate liner as presented on Sheet 1 of Appendix G, which is the equivalent K value and discharge comparison for the alternate liner systems. SCS acknowledges that the thickness of the 40-mil FML on Sheet 1 is incorrect and a revised calculation is attached, which yields the suitable demonstration of an equivalent hydraulic conductivity. Furthermore, the proposed ABL is an acceptable equivalent design based on the modeling presented in the alternate liner demonstration (Appendix F). SBI and SCS will work with the VDEQ to correct this typographical error on page G-1 and page G-4 of Appendix G. The hydraulic conductivity value for concrete used in the calculation does consider the expected degree of cracking, and is a typical value for concrete material. For the VLSS options utilizing precast concrete wall panels or vinyl sheet piling panels, the joints will be sealed to provide an appropriate hydraulic conductivity as reflected in the equivalence demonstration calculations. Comment 2: Liner equivalence demonstration calculations are not presented for the sidewall bench alternative liner options. It is unclear why the benches are not proposed to have a Subtitle D or double-liner system consistent with the proposed bottom liners. Golder recommends that the benches and sidewalls be equipped with Subtitle D or equivalent Geosynthetic Clay Liner (GCL)/HDPE type liner system. Response 2: The liner equivalence calculations presented in Appendix G do not address the sidewall bench Option 1 or Option 2 configurations due to the following: The Option 1 configuration is an alternate composite liner system (FML/GCL) that is incorporated into the Facility s existing Solid Waste Permit and has been installed in other cells at the Landfill; The Option 2 configuration analysis is presented in Appendix F (MULTIMED Demonstration) and contains the critical scenario for this sidewall bench option (and the sidewall vertical Option 2) based on the calculated infiltration value obtained from the HELP Model runs. Therefore, the results presented in Appendix F show the equivalence demonstration, reflecting the basis of the design, and is demonstrated to be acceptable based on EPA and VDEQ criteria. The alternate liner systems proposed for the sidewall bench and sidewall vertical have been demonstrated to be equal or better than that of the Subtitle D liner system in terms of the Dilution Attenuation Factor (DAF) value. In addition, it is anticipated that the sidewall single liner system will accommodate the amount of anticipated infiltration, given the slope of the sidewall when compared with the Alternate Bottom Liner System. Comment 3: The Design Report does not address the build-up of hydrostatic forces outside of the liner system causing deflection and potential failure of the liner system inward in the event of

76 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 19 gradient control failure. Similar to comment #1, the sealant of construction joints in the liner system is not addressed. Response 3: The build-up of hydrostatic forces outside of the liner system is implausible given the level of redundancy designed in the gradient control system. In the hypothetical scenario of a failure in the gradient control system, hydrostatic buildup of pressures outside of the liner system can be limited, or prevented, by pumping the cleanout piping that is connected to the bottom of the gradient control collection pipes. Even if some hydrostatic pressure was to build up, it would be resisted by lateral loads imposed by the waste acting directly on the inside face of the liner system. The magnitude of the lateral loads will be a function of vertical waste depth in the vicinity of the sidewalls. Should lateral movement occur, the waste will exert passive pressures on vertical walls. Under this condition, water levels would need to significantly exceed the height of the waste in order to cause a negative impact to the liner system, and this is highly unlikely. Assuming a waste density of 65 pcf, Kp of 3.0 and unit weight of water of 62.4 pcf, one foot of waste under passive pressure conditions is sufficient to counteract each 3 feet of differential water head. Additionally, since in-coming flow through the bedrock (recovery) sufficient to saturate the gradient control fill would be very slow, there will sufficient time to place additional waste against the walls to resist movement or otherwise lower the water buildup by pumping. Based on the calculated recharge rate, the Facility would have sufficient time to acquire and mobilize additional pumps and/or generators necessary to re-activate the gradient control system. The Facility intends to perform sealing of the construction joints and the specific products and methods to accomplish this will be identified in construction-level documents, which is typical for this type of activity rather than providing details and specifications for sealant at the permitting stage. Comment 4: The structural calculations for the vertical support system appear to assume fixity of the vertical member at the base of each vertical wall. However, no design or constructability details were provided on how the vertical structural members will be installed/fixed (i.e. concrete foundation sizing and structural requirements, sheet pile embedment depth). Response 4: Detail 6 on Sheet 75A of the Permit Design Drawings depicts the cast-in-place concrete underwall foundation as well as the anchor bolt for the concrete VLSS option. Development of construction-level details depicting dimensions for the concrete foundation as well as embedment depth for the sheet pile are beyond the scope of permit-level documentation. There is variability expected in the types of rock in which the vertical liner support system will be anchored. As such, the development of location-specific details for the various VLSS options for different areas of the quarry benches and sidewalls is appropriate. The configuration for securing the vertical structural member at the base of each segment of the quarry sidewall will be depicted on the construction documents and the dimensions and specifications for foundations and anchoring will be presented accordingly. Comment 5: There appear to be several inconsistencies in the structural calculations for the VZSS wall (i.e. is deflection calculated for the full 40-ft wall or just the 20-ft section above tie-

77 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 20 back? The calculation computes deflection for the 40-ft wall based on the loading of a 5-ft lifts of flowable fill, but only multiplies the deflection x 4 for the full wall. Additionally, it appears that the structural calculations do not verify maximum bending moment in the sheet pile wall. Response 5: The calculations incorporate an average height and a normalized configuration of the quarry sidewall between each bench for permitting purposes. The calculations have been included for permitting purposes; final structural calculations will be performed for the selected vertical support system option(s) prior to construction of each phase of the sidewall liner system. The deflection is calculated for each 20-ft section, not the 40-ft wall, because the tie-back limits deflection at the bottom of the upper 20-ft section. The location-specific anchoring, foundation, and other elements of the VLSS will be established to provide appropriate factor-of-safety considering deflection and maximum bending moment that will be experienced along the quarry sidewall considering the site-specific characteristics. Comment 6: Provide details for how the groundwater control and leachate collection systems will be constructed, accessed and operated during the early stages of landfilling prior to full completion of the riser pipes. Response 6: The Permit Design Drawings in Attachment III depict details of the locations, configuration, dimensions, materials of construction, and other aspects related to construction of the gradient control and leachate collection systems. The Design Report in Attachment IV and the Leachate Management Plan in Attachment VIII present the calculations regarding sizing of aggregate sumps, pipes, pumps, tanks, and other system features, as well as a narrative discussion on the intended operational procedures. Based on discussions with the County and Golder, SBI and SCS understand this comment is specifically directed toward the construction, access, and operation of the Leachate/Gradient Control Sideslope Riser Compound, which is described on Page 15 of the Design Report and depicted on the Drawings. Accordingly, this response outlines additional explanation regarding the plan for the initial phases of construction of the riser compound structure and the associated riser contingency access vault. The phased nature for construction of the sideslope riser compound structure is noted in Section on page 9 of the Design Report. If deemed necessary, SBI and SCS will work with VDEQ to insert the discussion below into Section The lower section of the sideslope riser compound will be constructed in conjunction with the sumps installed as part of the initial bottom liner system and will extend up to the lowest sidewall bench. Subsequent sections of the compound will be constructed in conjunction with each progressive section of the sidewall liner system and will temporarily terminate at the sidewall benches. Construction of the riser contingency access vault will be accomplished in stages coinciding with installation of the upper sections of the sideslope riser compound. Temporary discharge pipes will be connected to the portions of the riser pipes that are constructed during the initial construction stages. These pipes will extend up the quarry wall and be secured using appropriate pipe supports. These temporary pipes will be positioned along the edge of the quarry to connect to the leachate and gradient control forcemains. Secondary

78 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 21 containment, which may be in the form of double-walled pipe, a larger diameter pipe, or a geomembrane, will be provided for the temporary pipe transferring leachate. During construction of additional portions of the compound and associated riser pipes, pumping will alternate between the primary riser pipes and the spare riser pipes to allow the transfer pipes to be disconnected. Heavy-duty insulated power cables will be installed to connect the conduit, which runs parallel to the forcemain (as depicted in Details 6 and 9 on Sheet 76), and the pump power supply cables at the temporary termination of the riser pipes. A portable generator may be used to power the pumps, particularly during construction activities. Details of temporary pipe and electrical cable routing for a particular phase during and after construction will be developed as part of the preparation of construction drawings. Access to the temporary termination point of the sideslope riser compound during the early construction phases will be accomplished by accessing the sidewall bench or utilizing a mechanical lift, if necessary. Comment 7: The leachate/gradient control side slope riser pipe compound detail indicates that the riser compound will penetrate the vertical liner systems. However, no details have been provided as to how those penetrations will be constructed or sealed to ensure liner integrity. Response 7: The sideslope riser pipe compound will not penetrate the vertical liner system. The design for the Quarry Cell excludes any features that penetrate the various liner systems (bottom, sidewall vertical, or sidewall bench). The Permit Design Drawings confirm this: Detail 1 on Sheet 77 shows an 80-mil geomembrane will allow the leachate sideslope riser pipes to remain interior to the liner and the gradient control sideslope riser pipes to remain outside the liner. Both Details 1 and 4 on Sheet 77 indicate that concrete will be placed between the sideslope riser pipe compound and the quarry wall. Details 3 and 7 on Sheet 76 present the geomembrane transition from the bottom liner system to the sideslope riser pipes. Details 3 and 7 on Sheet 77 show continuous contact between the wall/liner system and the sideslope riser pipe compound. Detail 2 on Sheet 77 differs from these details in that it shows the riser pipes in the foreground and a nearby conceptual vertical liner system in the background. This detail is for reference purposes and incorporates an offset feature in a manner that is often shown in sectional views; therefore, it does not show the concrete surrounding the sideslope riser pipes. It will be necessary to transition the liner from the sideslope riser pipes to the sidewall and bench liner systems in the portion of the quarry adjacent to the side slope riser pipe compound. SCS anticipates that the sideslope riser compound will be transitioned in a similar manner to the soil sidewall liner system. In this case similar transition details will be used with concrete replacing

79 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 22 soil in those areas. These details will be developed based on the sidewall liner system selected for that portion of the quarry following the pre-construction inspection as part of the construction drawings. Comment 8: No down drag-tensile capacity evaluation of the superficial geotextile and geocomposite drainage layer was performed. While the geotextile is a superficial component of the liner system, the geocomposite drainage layer is critical to conveying leachate flows from the sidewall benches to the leachate collection system. Response 8: The design includes an 18-inch fluff layer (or a more appropriate term may be cushion layer) to serve both to protect the liner system from damage during waste placement and to provide a physical buffer between the waste and liner system that will reduce downdrag forces that may otherwise be transmitted to the liner system components. Furthermore, the woven geotextile interface with the non-woven geotextile that is integral to the GDN serves as a slip surface, allowing movement between the cushion layer and the geocomposite drainage net. This protects the geocomposite drainage net from experiencing damage or discontinuity due to potential downdrag forces that may be generated from waste settlement. The geocomposite drainage net and the geomembrane will be fastened to the sidewall. The non-woven geotextile facing of the geocomposite drainage net would remain intact in the event of movement and thus maintain the functionality of the leachate drainage layer. Comment 9: The Design Report calls for an 18-inch fluff layer to be constructed adjacent to the vertical liner system. However, the constructability of this layer was not addressed. Response 9: The fluff layer (or a more appropriate term may be cushion layer) is essentially a physical buffer between the waste and the sidewall liner system. It will consist of select material that is free from large or elongated particles, receives careful placement and compaction that results in close contact with the sidewall vertical and sidewall bench liner system, and that is free of large voids or other irregularities. Constructability is not an issue because the layer thickness is not necessarily limited to 18-inches, and will be placed ahead of the waste filling operations for each lift. This layer may be thicker for ease of construction and operations. A rigid or semirigid removable form device (such as plywood, sheet pile panel, etc.) may be used to facilitate placement of the cushion layer material. Refer to Section on page 27 of the Design Report Final Grades 9VAC O Comment 1: The slope stability calculations reference 3:1 final side slopes. However, these side slopes are not identified and therefore were not verified on the Permit Drawings. Response 1: On Sheet 55 (Final Grading Plan) in the Permit Drawings, the final cover system for cap #1 is referenced. Detail on the final cover system for cap #1 is shown on Sheet 74 (Typical Cap and Cell Details). Sheet 74 references the 3:1 final side slopes. The cross sections shown on Sheets also demonstrate that there are no slopes constructed from MSW that are steeper than 3:1. Section of the Closure Plan on page 7 states, Waste Disposal Cells 25 through 28, the quarry pit cells, and the landfill reconfiguration have not been constructed to-

80 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 23 date. The maximum final sideslopes for these fill areas will be no steeper than 3:1. Additionally, measurement tools such as AutoCAD dimension functions, Adobe analyze tools, or a standard engineering scale can be used to verify that no slopes depicted on Sheet 55 exceed the 3:1 threshold outlined in the closure plan. The slopes depicted on Sheet 55 have not been labeled as has been noted as part of this review. If the county requests, SBI will request that VDEQ add these labels Approved Plans 9VAC P Comment 1: The proposed design provides the Owner significant flexibility in the construction of the liner systems, based on site-specific conditions and the base design is based on an assumed quarry completion plan. In addition, there are several construction level reports and documents referenced throughout the Permit Application. Conditional approval of this permit application should require regulatory review and approval of all construction documents/plans in advance of construction. Response 1: Pursuant to the VSWMR, VDEQ oversees the implementation of the cell design, both through on-site inspections and by requiring periodic reports on construction progress and updates to the appropriate documentation and, ultimately, issues a Certificate-to-Operate (CTO) prior to initial waste placement and commencement of operations in the cell. The Facility is required to submit notification to VDEQ in advance of cell construction, submit any design changes prior to construction for approval, and notify VDEQ of the selection of liner system options prior to construction (refer to site-specific conditions I.F.1, I.F.2, and I.F10). SBI will copy the County on these notifications. Comment 2: More details should be provided on the construction of the gas collection system since it will be installed as the landfill is filled. Please provide details of the vertical Landfill Gas (LFG) collectors placed around the perimeter of the landfill and the access vault shown on drawing 68. Show connection details for the vertical collectors and LFG horizontal collector and demonstrate how these connections will be maintained with differential movement of the vertical collectors and the horizontal collectors. How will the vertical LFG collectors be supported? Response 2: The Permit Design Drawings in Attachment III depict details on the locations, configuration, dimensions, materials of construction, and other aspects related to construction of the landfill gas collection system in the Quarry Cell. Appendix D of the Landfill Gas Management Plan in Attachment IX presents the narrative discussion regarding well and collector spacing and orientation, header pipe sizing, condensate production, and other system features. As noted above, the LFG collection system is regulated by both the waste division and the air division of VDEQ. Prior to constructing the landfill gas (LFG) collection system in the Quarry Cell, the Facility will be required to update the existing NSPS LFG Collection and Control System Design Plan (Design Plan) in accordance with 40 CFR and the Facility s existing air quality permits. The updated Design Plan will be prepared and certified by a professional engineer licensed in Virginia and this Plan will be submitted to the VDEQ Division

81 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 24 of Air Quality for approval prior to the installation of the LFG system components. During the development of the Design Plan and subsequent construction documentation, the specific configuration, dimensions, materials of construction, and other design parameters for the vertical collectors and connection of the horizontal collector/vertical riser will be finalized. For purposes of development of the Solid Waste Permit Amendment documentation for the LFG collection system in the Quarry Cell, the impact of differential settlement was assessed and the measures that may be taken to maintain the connection at the horizontal collector/vertical riser are described. Please see Response 1.C.a for more details. The vertical LFG collectors that are positioned around the perimeter of the Quarry Cell will be installed in a phased manner and supported similar to the leachate cleanout piping. The lower section of the vertical collector will be constructed in conjunction with the leachate collection piping for the bottom liner system and will extend up to the lowest sidewall bench. Subsequent sections of the vertical collector will be constructed in conjunction with each progressive section of the sidewall liner system and will temporarily terminate at the sidewall benches. Permanent header pipes will be connected to the portions of the vertical collector riser pipes that are constructed during the initial construction stages. These pipes will convey LFG along the quarry sidewall benches to a temporary centralized trunk line that parallels the access ramp or, alternatively, temporary vertical collectors will extend up the quarry wall and be secured using appropriate pipe supports. During construction of additional portions of the vertical collector riser pipes, vacuum will be provided by a temporary connection to the adjacent riser pipe to enable continued LFG extraction. The details on Sheet 77 of the Permit Design Drawings depict the Riser Contingency Access Vault. Comment 3: Provide calculations for the HDPE SDR 17 horizontal laterals that show that they can withstand the overburden pressures from the waste and remain functional in the gas collection system under the most elevated operating temperature that is realistically expected (e.g., 180 degrees Fahrenheit is commonly observed). Response 3: Refer to Response 1.C.b and the attached pipe strength calculations. With respect to elevated temperatures, the existing waste disposal units at the Landfill have waste depths of approximately 200 feet, which is less than the maximum waste depths proposed for the Quarry Cell, but is sufficient waste mass to provide some indication of the temperatures that are anticipated to be produced in the Quarry Cell. The LFG wellhead temperatures measured on a monthly basis at the Landfill rarely exceed 130 degrees F, with the maximum temperatures of 145 F recorded on occasion at select wellheads. The temperatures within the waste mass at the Landfill have not proven to be detrimental to the integrity and performance of the existing HDPE SDR 17 and SCH 80 PVC piping that has historically been installed in the horizontal collectors and vertical wells at this Facility. HDPE and PVC materials are the industry-standard for LFG extraction wells at facilities where LFG wellhead temperatures are typically below 150 F and subsurface temperatures within the

82 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 25 waste mass are not expected to exceed 160 F or so. As noted, these materials have been suitable for the existing LFG collection system operating at this Facility for over 25 years and are considered to be suitable for the Quarry Cell. In the event that elevated temperatures greater than 180 degrees F are recorded in the Quarry Cell, the Facility will utilize CPVC, which is most often used for wells and collectors that are installed in locations where LFG wellhead temperatures are somewhat higher than 150 F. Based on SCS experience at other elevated temperature landfills (ETLF) during the past decade or so, steel pipe (carbon and stainless) is the most common material for wells that are installed in locations where LFG wellhead temperatures exceed 200 F. Another potential alternate material is ISCO Polystar pipe PP-RCT, which shares several similar characteristics with fiberglass, but has a polypropylene-random-copolymer for the interior and exterior coatings. This product is rated for vacuum use at 248 F (a temperature rating considerably higher than any of the other plastic piping materials used for LFG well casing) and states a capability of having long term strength of 377 psi at 230 F. In the event that the network of horizontal collectors are proven to be ineffective and nonfunctional, the Facility will install deep vertical wells. This is technically feasible, although such installation is typically more difficult, requires longer drilling schedules, and increased costs. Comment 4: It is not clear why a detail for a vertical LFG collection well is provided if vertical wells are not deemed appropriate for the LFG system. Please provide information about how the vertical wells will be integrated with the system of lateral collectors. The DEQ draft permit modules indicate that has wells will be installed to 75% of the waste mass thickness. This requirement is inconsistent with the permit drawings and design documents. Response 4: The historical practice at the Landfill has been to install horizontal collectors in conjunction with waste placement operations and then to install vertical LFG extraction wells to enhance LFG recovery upon achieving sufficient waste depths. While certain aspects of the Quarry Cell may not require the implementation of vertical wells, the Permit Design Drawings and Appendix D of the LFG Management Plan were not intended to communicate that use of vertical wells is inappropriate for the Quarry Cell. SBI anticipates continuing this historical practice once filling operations move into the Quarry Cell. The Facility will likely install vertical extraction wells, which can be drilled to depths of 150 feet or more. As discussed in Section 3.0 of Appendix D of the LFG Management Plan, the wellheads to provide control to vertical extraction wells may be extended up as additional waste lifts are placed, or they may be routed to the nearest sidewall bench where a connection to a vertical collector or riser pipe that serves as a manifold for the header piping that transports LFG along the sidewall bench can be accomplished. The vertical well detail depicted on Sheet 68 was provided for reference. Prior to constructing the vertical LFG extraction wells in the Quarry Cell, the Facility will be required to update the existing NSPS LFG Collection and Control System Design Plan (Design Plan) in accordance with 40 CFR and the Facility s existing air quality permits. During the development of the Design Plan and subsequent construction documentation, the proposed wellfield layout and

83 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 26 spacing, vertical LFG extraction well depths, dimensions, and materials of construction will be finalized. The Facility has discontinued use of HDPE SDR-17 for vertical well riser pipes and installed SCH 80 PVC during the past several wellfield expansion projects. The detail on Sheet 68 identifies either material as acceptable. SBI and SCS will request that the VDEQ remove or clarify the reference for well depths extending to 75% of the waste depth CQA Plan 9VAC Q Comment 1: The Technical Specifications and CQA Plan should provide detailed construction specifications, material requirements, and construction testing requirements for all materials and components proposed as part of the design, including all systems, liners, and final cover. This includes HDPE pipe, structural materials for the VZSS, backfill materials behind the VZSS system including earthen backfill, flowable fill, grout, and VZSS joint sealant materials, and final cover materials. While it is acknowledged that these technical specifications may not be required for permit level approval, the Technical Specifications and CQA Plan appear to provide comprehensive material specifications and requirements for geosynthetic liner materials, but do not provide any substantive specifications or requirements for pipe or structural members which are critical components of the design and must be adequately designed for system performance. Response 1: The Technical Specifications and CQA Plan address the requirements pertaining to the Quarry Waste Disposal Unit, which is the subject of this Solid Waste Permit amendment for Cell 28. Requirements for materials such as HDPE pipe that are common to previous cells of the Shoosmith Landfill are not necessarily repeated in the Technical Specifications, and/or CQA Plan for Cell 28. The specific technical requirements mentioned by the commenter are addressed as follows: VLSS materials are addressed in CQA Plan 3.0 Vertical Liner Support System Materials. Specifications will be finalized prior to construction, depending on which VLSS option is selected. Backfill materials are addressed in CQA Plan 2.0 Earth Materials, Specification Section Earthwork Quarry Cell, and in the current permit. Final cover materials are addressed in CQA Plan Soil Liner/Cap Test-Pad and 4.0 Geosynthetics, technical specifications listed in Division 13 Special Construction, and in the current permit. Concrete materials are addressed in CQA Plan 3.2 Concrete Materials, as well as Specification Section Concrete. HDPE pipe is addressed in Specification Section Pipe, Fittings, and Appurtenances.

84 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page Final Cover 9VAC D Comment 1: The Design Report does not address the proposed final cover system, specifically the equivalence and performance of the separate final cover sections proposed for the landfill crown slopes and side slopes relative to compliance with regulation. Response 1: The proposed final cover system is addressed in Section of the Closure Plan, which was included in the Quarry Waste Disposal Unit Permit Amendment Application. The equivalence was discussed on page 6 and supplemental HELP Model runs were included in Appendix B of the Closure Plan. The two final cover system configurations that are incorporated into the Facility s existing Solid Waste Permit are applicable for the existing and proposed waste disposal units, including the Quarry Cell. 4.0 ENVIRONMENTAL MONITORING PROGRAMS 4.1 VSWMR GROUNDWATER MONITORING PROGRAM Groundwater Monitoring Program 9VAC Comment 1: According to the Groundwater Monitoring Plan (GMP) Once a sufficient mass of waste is in place to balance the upward pressure of the groundwater system on the landfill liner, the pumping of the gradient control system can be stopped. At least 1 year prior to turning off the pumping system, a proposed monitoring plan will be submitted to DEQ to address any changes to the inward gradient and the need to install additional perimeter downgradient wells. Golder recommends that the GMP address both current and future conditions. Response 1: The GMP documents current groundwater flow conditions as shown on the Groundwater Surface Contour Map provided as Drawing 4. The GMP will be updated to conform with language in the draft Permit Module I (I.F.21.) which states that within one year of turning off the inward gradient pumping system, the facility shall submit to the Department a report evaluating whether or not the aquifer system has returned to equilibrium. The report shall also evaluate the need for additional perimeter groundwater monitoring wells, both shallow and deep. To address the comment on future conditions, the updated GMP will include a drawing that illustrates the projected groundwater flow conditions once the aquifer has returned to equilibrium. As will be indicated on the drawing, projected groundwater flow patterns are based on current data and may change. In accordance with draft Permit Module I.F.21, the proposed groundwater monitoring network will be evaluated and changes made should they be warranted based on the conditions at the time Groundwater Monitoring System 9VAC A.3 Comment 1: The Groundwater Monitoring Plan (GMP) does not match statements in the Landfill Gas (LFG) Management Plan with respect to the groundwater and LFG monitoring networks. The GMP says that P 203, P 206, and P 212 (among others) will be converted to groundwater monitoring wells. The LFG Plan says that P 202 through P 206, P 210, P 212, and P 116 will be converted to LFG probes. The Site Monitoring Plan drawings in the LFG Plan

85 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 28 do not match either the LFG Plan text or the GMP. Golder recommends that the documents be reviewed and clarified/corrected as needed for consistency. Response 1: Piezometers P-206 and P-212 were incorrectly included in the list of existing piezometers to be converted to LFG monitoring points under Section 2.2 on page 2 of the LFG Management Plan in Attachment IX. The Groundwater Monitoring Plan states that P-203D, which is adjacent to P-203, will be converted into a groundwater monitoring well, not P-203 so this is not inconsistent. The drawings in the LFG Management Plan, Groundwater Monitoring Plan, and Permit Design Drawings, and specifically the Site Monitoring Plan Drawing that is included in all three documents, depict consistent information with each other. SBI and SCS will work with the VDEQ to correct this typographical error on page 2 of the LFG Management Plan. Comment 2: The groundwater monitoring network includes five gradient control sampling locations in the Quarry Cell (one at the bottom, four on the benches). The GMP states that if no volatile organic compounds (VOCs) are detected in the four bench samples at concentrations above the Quantitation Limit (QL), then future sampling will only be at the one bottom gradient control point. If the bottom gradient control sample has quantified VOC detections in the future, the other bench points may be sampled independently to try to determine the source area of the contamination. Golder recommends that this section of the GMP be revised to include provisions for four quarters of sampling and associated statistical analyses following in service placement of each gradient control system level with the detection limit (DL) used as the screening criterion so as to meet the highest level of environmental protection (contaminant identification) possible. The list of initial screening analytes should be expanded beyond VOCs to include metals, radio nuclei, biological oxygen demand (BOD), chemical oxygen demand (COD), ammonia, total nitrogen, and phosphorus. Response 2: Groundwater around the quarry disposal unit will be monitored via a series of groundwater monitoring wells that constitute the groundwater monitoring network. This network is further described in the GMP. The five gradient control sampling points are not considered a part of the groundwater monitoring network, but are instead used to monitor the quality of groundwater seepage prior to discharge. The GMP and draft Permit Module I include analysis of the gradient control samples for VOCs. SBI believes that VOCs are the best indicators of a release from the quarry disposal unit. However, to address any further concerns, SBI is willing to agree to voluntarily analyze the first four gradient control samples for the initial screening analytes suggested above following inservice placement of each gradient control system level. Since no specific metals are specified in the Comment, SBI would like to confer with Golder as to which metals are suggested for analysis. The initial four quarters of sampling results will be subjected to statistical analysis to determine statistically significant increases (SSIs) over background. For VOCs, an SSI will occur if a VOC is confirmed above the laboratory QL. For BOD, ammonia, and zinc (among other metals to be agreed upon for analysis), the Numeric Effluent Limitations listed in Table of the Virginia

86 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 29 Pollutant Discharge Elimination System (VPDES) General Permit for Stormwater Discharges Associated with Industrial Activity (VAR05), Sector L for landfills, will be used to determine an SSI. Analytical results of the remaining analytes will be compared to site-specific background values. Comment 3: The GMP states that if a VOC is detected in a gradient control sample at a quantified concentration, the operator has 30 days to complete verification re-sampling. If the re-sampling refutes the detection, the gradient control water may continue to be discharged. If the re-sampling confirms the detection, the operator has another 30 days to divert the discharge to the leachate system. Justification for this approach should be provided. In concept it would allow the discharge of solid waste constituents for as long as 60 days. Golder recommend consideration of immediate diversion once a VOC or other contaminant is detected (above the DL), pending the results of verification re-sampling. Response 3: Gradient control water will immediately be diverted away from discharge to Swift Creek upon receipt of the initial SSI (as defined in the response to Comment 2 above). If verification sampling refutes the SSI, the gradient control water will continue to be discharged. If verification sampling confirms the SSI, diversion will continue until such time as it is determined that the water no longer exhibits SSIs. Comment 4: No discussion is provided regarding the mining operation s dewatering program with respect to historical analytical monitoring data and Virginia Pollutant Discharge Elimination System (VPDES) permit limits. Golder recommends that a compilation and evaluation of available analytical data for the mining dewatering discharge be prepared to develop an understanding of existing groundwater quality as it relates to the gradient control monitoring points in GMP. Response 4: SBI will review the quarry s available historical analytical monitoring data prior to implementing the Gradient Control Sampling Plan. The GMP will be adjusted if necessary based on that review. Comment 5: The monitoring network includes underdrain samples (10 locations in the original landfill) for analysis of VOCs. Similar to the gradient control points, if a VOC is detected in an underdrain sample at a quantified concentration (above the QL), the operator has 30 days to complete verification re-sampling. If the re-sampling refutes the detection, the underdrain water may continue to be discharged. If the re-sampling confirms the detection, the operator has another 30 days to divert the discharge to the leachate system. Justification for this approach should be provided as it appears it would allow the discharge of solid waste constituents for as long as 60 days. Recommend consideration of immediate diversion once a VOC or other contaminant is detected (above the DL), pending the results of verification re-sampling. Response 5: The ten existing underdrains are part of the existing permitted waste disposal units at the landfill and are not the subject of DEQ s current permitting action. Nine of the ten underdrains have been dry since cell construction and the tenth underdrain only discharges when pumped.

87 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page Groundwater Sampling & Analysis Requirements 9VAC A.4 Comment 1: Adequately addressed. Response 1: No response required Groundwater Protection Standards 9VAC A.6 Comment 1: According to the GMP, two different background databases will be established: one for saprolite/overburden (using upgradient well MW 115), and one for bedrock (using upgradient wells MW 114R and MW 203D). It is unclear which background will be used to establish the GPS for constituents for which background is above the regulatory limits. Recommend asking for clarification. Response 1: Background-based GPS, if necessary, will be established separately for each monitoring network saprolite/overburden and bedrock. As provided in the GMP, background values (potentially used as GPS) will be calculated for the saprolite/overburden using data from MW-115. Background values will be calculated for the bedrock using data from MW-114R and MW-103D Monitoring for Sanitary Landfills 9VAC B Comment 1: The GMP states that the inward gradient design exempts the Quarry Cell from the quarterly groundwater monitoring frequency per House Bill 2471 until such time as the pumping stops, at which time the frequency will change from semi-annually to quarterly. No demonstration is provided to justify this assertion. Code of Virginia states, Groundwater monitoring shall be conducted at least quarterly by the owner or operator of any existing solid waste management landfill, accepting municipal solid waste, that was constructed on a wetland, has a potential hydrologic connection to such a wetland in the event of an escape of liquids from the facility, or is within a mile of such a wetland, unless the Director determines that less frequent monitoring is necessary Golder recommends that a formal demonstration be prepared at this time since it appears a hydrologic connection may exist if contaminated water could be pumped to Swift Creek for discharge (even if only for 60 days as currently proposed). Response 1: The GMP text will be revised to correspond with the language in the Gradient Control Sampling Plan and the draft Permit Module (I.F.20.3.a.) relating to quarterly sampling of the gradient control sampling points. Comment 2: The sampling frequency and parameters for the gradient control points are unclear; there are inconsistencies within the GMP text and Gradient Control Sampling Plan (App. III of the GMP). Recommend asking for clarification. Response 2: See response to Comment 1 above.

88 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page Statistical Methods & Constituent Lists 9VAC D Comment 1: The constituent lists cited in the GMP for the Detection and Assessment Monitoring Programs are the standard parameters for municipal solid waste landfills. However, the Quarry Cell has a history of mining, which uses blasting in its operation. Golder recommends that an evaluation of the blasting techniques used during the mining operation, including the chemical composition of the explosives introduced into the subsurface, and their potential effect on groundwater quality be performed. Consideration should be given to adding blasting-related constituents to the monitoring lists for both Detection and Assessment Monitoring, e.g., ammonia, biological oxygen demand (BOD), total petroleum hydrocarbons diesel range organics (TPH-DRO), and nitrates. Additionally, due to the presence of relatively freshly exposed granitic bedrock that is commonly affiliated with certain radioactive nuclei, Golder recommends that the potential for radioactive nuclei be evaluated and that appropriate parameters be included in the monitoring program. Response 1: In order to address the concern about hypothetical impacts to groundwater beneath the quarry from mining activity, SBI volunteers that, prior to developing Cell 28, evaluation of the above hypothetical impacts be performed, and if deemed warranted, be monitored separately from the GMP under consideration. The constituents listed would be analyzed in the gradient control samples during the first four quarters following operation of the gradient control levels and subjected to the same statistical analysis discussed in the response to Comment 2 under above. The granite quarrying process does not alter the naturally occurring levels of radon or radioactivity, and does not generate additional radon or radioactivity, therefore evaluation of radioactive nuclei is unnecessary Record Keeping & Reporting 9VAC E Comment 1: Adequately addressed. Response 1: No response required. 4.2 VSWMR LANDFILL GAS MONITORING PROGRAM Landfill Gas Monitoring Program 9VAC Comment 1: The Landfill Gas (LFG) Management Plan says that Shoosmith (not a 3rd party consultant) will perform the LFG monitoring. On occasion a consultant may do the monitoring. Golder recommends that Shoosmith consider the use of a 3rd party consultant with appropriate credentials to perform the monitoring and provide adequate documentation to ensure compliance. Response 1: SBI s current practice is to utilize a third-party entity to conduct the LFG monitoring. Landfill or third-party personnel will be properly trained and will abide by the applicable regulations pertaining to landfill gas monitoring which is described in detail in the

89 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 32 Landfill Gas Management Plan. SBI and SCS will work with VDEQ to modify this sentence in the LFG Management Plan. Comment 2: According to the LFG Plan, once the Quarry Cell is operational, there will be insufficient LFG flare capacity in the event the LFG-to-energy operation shuts down. Suggest requiring the additional flare capacity as a condition of operating in the Quarry Cell. Response 2: Based on historical and current LFG recovery rates, there does not appear to be a need for additional flare capacity in the near-term future, including upon initiating waste placement in the Quarry Cell. The LFG Management Plan states that, based on theoretical modelling of landfill gas production, a potential need could exist at some future date, if the existing landfill gas-to-energy project is shutdown. If the LFG recovery quantities approach the cumulative design capacity of the three existing flares, and the power plant demonstrates prolonged shutdowns in the future, more flare capacity will be added. Please note that the Facility s existing air quality permits that were recently amended by VDEQ Division of Air Quality already incorporate a future scenario for adding additional flaring capacity and so the facility is subject to such a condition already Landfill Gas Monitoring Network 9VAC B Comment 1: The LFG Plan does not match the GMP with respect to the LFG and groundwater monitoring networks. The GMP states that P 203, P 206, and P 212 (among others) will be converted to groundwater monitoring wells. The LFG Plan says that P 202 through P 206, P 210, P 212, and P 116 will be converted to LFG probes. The Site Monitoring Plan drawings in the LFG Plan do not match either the LFG Plan text or the GMP. Recommend asking for clarification. Response 1: Piezometers P-206 and P-212 were incorrectly included in the list of existing piezometers to be converted to LFG monitoring points under Section 2.2 on page 2 of the LFG Management Plan in Attachment IX. The Groundwater Monitoring Plan states that P-203D, which is adjacent to P-203, will be converted into a groundwater monitoring well, not P-203 so this is not inconsistent. The drawings in the LFG Management Plan, Groundwater Monitoring Plan, and Permit Design Drawings, and specifically the Site Monitoring Plan Drawing that is included in all three documents, depict consistent information with each other. SBI and SCS will work with the VDEQ to correct this typographical error on page 2 of the LFG Management Plan. Comment 2: The LFG Plan does not identify off-site structures within 1,000 feet as being in the LFG monitoring network, as required in the VSWMR (9VAC B.2.d). Suggest requesting information as to whether there are any off-site structures within 1,000 feet of the waste disposal unit, and if so, justification for not including them in the LFG monitoring network. Response 2: The Landfill Gas (LFG) Migration Monitoring Program is discussed under Section 2.3 beginning on page 3 of the Landfill Gas Management Plan. The Plan states that structures that are within the facility boundary and within the vicinity of the Quarry Cell where potential for LFG accumulation may occur will be monitored. The Plan describes the frequency of

90 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 33 monitoring, the instrument to be used, and the level where corrective actions need to be taken. The Plan also describes the network of monitoring probes that will detect subsurface LFG that has the potential to migrate beyond the Facility Boundary. With respect to designing a monitoring network to account for off-site inhabitable structures that are located within 1,000 feet of the Facility Boundary as required in VSWMR Section 200.B.2.d, please note the following: There are three off-site inhabitable structures that are within 1,000 feet of the Facility Boundary surrounding the Quarry Cell. These include one structure to the west of Swift Creek, and two businesses to the east. The LFG Management Plan for the Quarry Cell included in Attachment IX is consistent with the Initial LFG Management Plan, which has been approved and followed for over 20 years. The plan addresses all other portions of the Landfill, and is incorporated into the Facility s current Solid Waste Permit, and this monitoring network has been designed to account for off-site inhabitable structures. There are proposed monitoring probes positioned between the Quarry Cell and these off-site structures, which is typical for accounting for off-site inhabitable structures in the design of the Facility s monitoring network Landfill Gas Remediation 9VAC C Comment 1: Adequately addressed. Response 1: No response required Odor Management 9VAC D Comment 1: An Odor Management and Control Plan for the facility, dated July 15, 2010, was located on the internet. An Odor Management Plan was initially prepared in 1998 to comply with Condition 22 of the CUP, and has been updated periodically. Response 1: As required by the Facility s air quality and solid waste permits, the Odor Management Plan is reviewed annually and updated as necessary. The annual evaluation is submitted to VDEQ. Comment 2: Given the thickness of the proposed waste mass, the facility location in an urban area, and the potential for system failure based on the elevated stresses and loads that will exist at full build-out, Golder recommends that the Odor Management and Control Plan be updated for a contingency response to an elevated temperature event (and the associated odor) in the landfill such as has occurred at Bridgeton (MO), Countywide (OH), Murfreesboro (TN), and Waimanalo (HI).

91 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 34 Response 2: The existing Odor Management and Control Plan is reviewed and a report is submitted to VDEQ on an annual basis. During the next Plan review cycle, the Facility will evaluate whether it is appropriate to incorporate a contingency response that anticipates an elevated temperature event based exclusively on the premise that such an event has occurred at a few MSW landfills in the US. 4.3 COUNTY WASTEWATER DISCHARGE PROGRAM Comment: Based on review of the available documents and in consideration of the potential gradient control flows that may require management as leachate should they become impacted, Golder recommends development of a pre-treatment plan for the potential treatment and discharge the gradient control water. This plan is significant because, if the gradient control water becomes impacted such that it can no longer legally be discharged under the allowable non-stormwater discharge provisions of the facility s Virginia Pollutant Discharge Elimination System (VPDES) stormwater permit (subject to $32,500 per day fines), immediate alternative management means will be required if insufficient materials are not present to counteract the hydrostatic buoyancy pressure on the liner (i.e., if sufficient counter weight is present, the facility operator could temporarily terminate the pumping activities as needed until such time as the means for an alternative disposal are put in place). Failure to counter act the hydrostatic pressure in a timely manner may result in separation of the liner from the vertical liner mounting system resulting in structural failure and likely unrepairable damage to the liner system. The pre-treatment plan should address the requirements (permitting and operational) for the likely discharge location (e.g., Chesterfield County Sewer or industrial wastewater surface discharge to Swift Creek). The pre-treatment plan should address in detail the means and methods for treating the wastewater to mitigate predicted elevated concentrations (or observed based on existing leachate and landfill gas condensate monitoring data) of commonly observed MSW leachate and landfill gas condensate contaminants, including, but not limited to: Acetone, Methyl ethyl ketone, Ammonia, Biological oxygen demand (BOD), and Chemical oxygen demand (COD). Endpoint target concentrations for treatment should be based on County discharge standards [i.e., Total Toxic Organic (TTO) limits plus any parameter specific limitations] and/or Virginia Water Quality Standards, including Chesapeake Bay Total Maximum Daily Load (TMDL) limitations if a surface discharge is anticipated. If a County sewer discharge is envisioned, Golder recommends that a letter of capacity availability be obtained from the County to ensure that the County will be able to manage the additional flow if required. If a private pump and haul disposal is envisioned, a letter of capacity availability should be obtained from the potential disposal company. Additionally, unless the facility-operator is able to obtain a letter of capacity or similar assurance for additional disposal capacity via the County sewer, Golder recommends that a bypass flow analysis be performed to determine the minimum amount of on-site storage

92 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 35 capacity that may be required to manage impacted gradient control water in the event that surface discharge is no longer a viable option pending the completion of arrangements for alternative disposal means. Response: The potential future scenario in which gradient control water becomes impacted such that it can no longer legally be discharged under the allowable non-stormwater discharge provisions of the facility s Virginia Pollutant Discharge Elimination System (VPDES) stormwater permit may be hypothetically possible, but it is highly unlikely. While hypothetically some quantity of impacted gradient control water could potentially be prohibited from being discharged directly to surface waters at some unknown point in the future, the requirement to develop a pre-treatment plan at this time in anticipation that it would require management as a high-strength industrial wastewater, such as leachate, is extreme and is not supported. Several considerations regarding this issue are as follows: An estimate of the potential quantity of hypothetically impacted gradient control water would be entirely speculative. Note that the Quarry Cell design includes collection of gradient control water from multiple elevations and the ability to segregate into zones. Similarly, addressing in detail the means and methods for implementing treatment for predicted concentrations of hypothetically impacted gradient control water would also be entirely speculative. The unit processes and methods for treatment of marginally impacted groundwater are different for various constituents of concern. There is no need to address now some hypothetical future permitting and operational requirements related to a potential discharge location resulting from impacted groundwater pump and treatment, when such a condition has not occurred during the landfill s 40 years of operation. The design, construction and operation of the Quarry Cell do not increase the likelihood of such a scenario occurring. If treatment using common groundwater pump and treat methods were implemented, it is reasonable to assume a high percentage of the treated gradient control water will be suitable for surface discharge, while a relatively low percentage may require disposal at in the County s sanitary sewer system. Based on SCS experience with pump and treat operations at unlined landfills, it is uncommon for the post-treatment liquids to be routed to a sanitary sewer system for disposal. 4.4 COUNTY UTILITIES Comment: There has been concern expressed by various County departments regarding the design of the internal Leachate system. A supplemental plan needs to be created to address the interior layout of the leachate collection system as it drains to the pretreatment area. Additionally, as various cells are raised and capped, a phasing plan needs to be shown indicating whether or not the leachate collection lines will be periodically relocated or will be buried under an extreme amount of cover. The plan should indicate the material types of the

93 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 36 collection lines and whether or not they are cased (sleeved). The plan should have the grading dithered and the sanitary collection system darkened for visibility. Finally, provide information on the pump system which will limit the effluent to the maximum discharge of 120,000 gpd or 83 gpm. Response: The Permit Design Drawings and Leachate Management Plan provide extensive detail regarding the location, alignment, configuration, dimensions, materials of construction, and other design parameters for the leachate collection system that is to be installed within the Quarry Cell limits as well as the existing and proposed infrastructure that will convey the leachate to various storage, pre-treatment, and discharge locations at the Facility. The details on Sheet 76 of the Drawings related to materials and the Owner s option to provide a secondary containment pipe. Based on discussions with the County and Golder, SBI and SCS understand this comment may be specifically directed toward the removal/abandonment of the leachate forcemain pipe that will be positioned along the southern rim of the Quarry Cell (north of Cell 26 and west of Cell 27) at some future date when the liner system will be constructed along the edge of the quarry. Refer to the note on Sheet 55 of the Permit Design Drawings for explanation. The mechanism to restrict discharges into the County s sanitary sewer system is addressed in the existing Wastewater Discharge Permit. SBI and SCS are always willing to meet with County staff to better understand any concerns and collaborate on how best to address those concerns. 4.5 VPDES STORMWATER MONITORING PROGRAM Stormwater 9VAC Comment 1: Permit Condition I.F.20 in Module I states that, prior to operating in the Quarry Cell, the operator shall submit to the DEQ a request to discharge stormwater off-site and/or through the facility s stormwater detention ponds. DEQ will evaluate the need for a new or revised VPDES or Water Permit at that time. Recommend requesting a stormwater management plan to include state and local permit requirements. Response 1: Upon issuance of the amended Solid Waste Permit by VDEQ, the Facility will be required to comply with Permit Condition I.F.20. In addition to Permit Condition I.F.20, SBI is required to comply with all applicable regulatory requirements regarding stormwater. Stormwater management is regulated by both VDEQ and Chesterfield County through a separate regulatory process. The purpose of the condition is to further reinforce SBI s obligation to comply with those processes. The landfill s existing stormwater management plan will be updated in accordance with those requirements. It would be premature to do so as part of the solid waste permitting program.

94 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 37 Comment 2: DEQ also noted in Permit Condition I.F.20 that the facility may be subject to additional MS4 requirements from Chesterfield County. Recommend requesting clarification from County staff. Response 2: As noted above, the facility s stormwater discharges are regulated by separate regulatory programs managed by both VDEQ s Division of Water and Chesterfield County. The draft permit reinforces SBI s obligation to comply with all regulatory requirements associated with its stormwater discharges. Under the proposed design, stormwater will not be discharged into the County s storm sewer, and thus the Facility would not be subject to the County s MS4 requirements. SBI will be coordinating with both VDEQ and the County to ensure that all stormwater regulatory obligations are satisfied. Those requirements will be addressed through the separate regulatory programs rather than through the solid waste permitting process. 4.6 VPDES GRADIENT CONTROL DISCHARGE MONITORING PROGRAM Gradient Control Water 9VAC Comment 1: Permit Condition I.F.20 states that, prior to operating in the Quarry Cell, the operator shall submit to the DEQ a request to discharge groundwater from the gradient control system off-site and/or through the facility s stormwater detention ponds. DEQ will evaluate the need for a new or revised VPDES or Water Permit at that time. Recommend requesting a gradient control water management plan that addresses the means and methods that will be used to manage the water, including expected volumes, quality, locations, permits, contingency plans, and emergency response actions. Response 1: A gradient control plan was developed and included in the Solid Waste Permit Amendment Application in Appendix H of the Design Report. The gradient control plan addresses the expected volumes, means and methods to manage the water, and discusses contingency capacity. A Gradient Control System Sampling and Analysis Plan was developed which included the methods to monitor quality, locations of sampling, and contingency sampling procedures. Emergency operation of the gradient control system is discussed in Section on page 38 of the Design Report. The Permit Design Drawings provide details about the gradient control system. Sheet 52 of the Permit Design Drawings shows the locations of the gradient control collection pipes, the gradient control mezzanine level collection pipes, the gradient control collection pipe cleanouts, the gradient control sump, the gradient control sideslope riser pipes, and the gradient control discharge locations. Sheet 76 of the Permit Design Drawings shows the location of the gradient control pipes relative to the liner system in Detail 1, the location of the gradient control drainage sump relative to the leachate collection sump in Detail 2, and the location of the gradient control sideslope riser pipes relative to the leachate collection side slope riser pipes in Detail 7. Sheet 77 of the Permit Design Drawings shows the locations of primary and contingency side slope riser pipes relative to the leachate collection sideslope riser pipes in Detail 1, the location of the mezzanine level gradient control collection pipe relative to the sidewall liner system in Detail 6,

95 ATTACHMENT 2 Mr. Michael G. Williams, PG August 23, 2015 Page 38 the locations of mezzanine level gradient control collection pipe connection in Detail 7, the sampling port design to ensure proper sample quality is shown in Detail 8, and contingency piping for directing groundwater to a treatment system is shown in Detail 9. The Facility will be governed by Permit Condition I.F.20 and VDEQ has indicated that the gradient control plan and related documentation included in the Solid Waste Permit Amendment provides sufficient information. In response to VDEQ s Technical Review Comment No. 2, SCS has contacted the VDEQ Water Permit Manager on behalf of SBI regarding the collection of groundwater via the gradient control system within the Quarry Cell and the subsequent discharge into Sediment Basin 7 and ultimately into Swift Creek. SCS and SBI are working with VDEQ Division of Water Quality to identify any permits that may be necessary once the commercial quarry operations cease and waste placement operations with the Quarry Cell commence. The Facility is governed by an existing VPDES Industrial Stormwater General Permit, and the permit renewal application submitted to the VDEQ Division of Water Quality included drawings which identify the Quarry Cell. Also, as Permit Condition I.F.20 states, the need for a new or revised VPDES or Water Permit will be determined by the VDEQ-DWQ. Until this determination has been made, the permitting requirements are uncertain. These requirements will be addressed through the water regulatory program rather than the waste program. Thank you again for the opportunity to provide these responses. SBI and SCS look forward to continuing to work with the County to address any questions regarding the landfill operation or the construction of the Quarry Cell. Please contact either of the undersigned or Bruce Coble of SBI at (804) if you have questions about these responses or require additional information. Sincerely, Charles J. Warren, PE Senior Project Engineer Robert E. Dick, PE, BCEE Project Director SCS ENGINEERS RED/CJW:asd cc: Bruce Coble, SBI Enclosures

96 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO SHOOSMITH SANITARY LF SHEET NO. CALCULATED BY CHECKED BY 1 RED RHI OF DATE DATE 3 8/23/2015 8/23/2015 SUBJECT ALTERNATE LINER K COMPARISON Compute the equivalent hydraulic conductivity (K z ) of a layered system using the relationship is as follows: K z = equivalent hydraulic conductivity (perpendicular to the layers) = [d 1 +d 2 +d 3 +..]/[d 1 /K 1 + d 2 /K 2 + d 3 /K 3 + ] Material Characteristics from Design Report, HELP Model, and Technical Specifications: d= Thickness (cm) K= Hydraulic Conductivity (cm/s) 60-mil Flexible Membrane Liner (FML): 40-mil Flexible Membrane Liner (FML): E-12 K from Koerner, E-12 K from Koerner, 1990 Compacted Clay Liner (CCL): E-07 K maximum per VSWMR / Specs Geosynthetic Clay Liner (GCL): Geosynthetic Clay Liner (GCL): E-09 K maximum per VSWMR E-09 K maximum per Specs Calculate Kz for the various liner systems: Subtitle D Liner: d= Thickness (cm) K= Hydraulic Conductivity (cm/s) FML CCL E E-07 Total = Equivalent K z = Equiv. Permittivity= 3.03E E-11 Prescriptive VSWMR Alternate Liner: FML E-12 GCL (per VSWMR) E-09 Total = Equivalent K z = Equiv. Permittivity= 3.78E E-11 Proposed Alternate Bottom Liner (FML/GCL/FML): FML GCL (per specs) E E-09 FML E-12 Total = Equivalent K z = 2.64E-11 Equiv. Permittivity= 3.059E-11 Applying Darcy's Law, which considers thickness of the liner systems and gradient, the proposed Alternate Bottom Liner (FML/GCL/FML) liner yields and less overall infiltration compared to the Subtitle D and the Prescriptive VSWMR ABL as demonstrated by a comparison of Equivalent Permittivities (values less than 1.0 indicate less infiltration than the respective standard liner): Permittivity Proposed ABL : Permittivity FML/24" CCL (Subtitle D) = 0.62 Permittivity Proposed ABL : Permittivity FML/GCL (Prescriptive ABL) = 0.62 Offices Nationwide

97 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO SHOOSMITH SANITARY LF SHEET NO. CALCULATED BY CHECKED BY 1 RHI RED OF DATE DATE 3 6/11/2014 8/23/2015 SUBJECT ALTERNATE LINER DISCHARGE COMPARISON Compute the discharge through a layered system following Giroud, 1997 for gravity flow (advective flow) using: Q = discharge through the layered system = (h+t 1 +t 2 )/((t 1 /k 1 )+(t 2 /k 2 )) h=hydraulic head = 30 cm (max) Material Characteristics from Design Report, HELP Model, and Technical Specifications: From Design Report, HELP & Specs: 60-mil Flexible Membrane Liner (FML): 40-mil Flexible Membrane Liner (FML): t= Thickness (cm) K= Hydraulic Conductivity (cm/s) E-12 K from Koerner, E-12 K from Koerner, 1990 Compacted Clay Liner (CCL): Geosynthetic Clay Liner (GCL): E E-09 K maximum per VSWMR / Specs K maximum per VSWMR Geosynthetic Clay Liner (GCL): E-09 K maximum per Specs t= Thickness (cm) K= Hydraulic Conductivity (cm/s) Subtitle D Liner: FML CCL E E-07 Total = Discharge Through System 4.522E-09 cm 3 /sec Prescriptive VSWMR Alternate Liner: FML GCL (per VSWMR) E E-09 Total = Discharge Through System 1.527E-09 cm 3 /sec Proposed Alternate Bottom Liner (FML/GCL/FML): FML GCL (per specs) E E-09 FML E-12 Total = Discharge Through System 9.443E-10 cm 3 /sec Giroud's Method, which applies Darcy's Law for a layered system under gravity flow (advective) under the maximum leachate head of 30 cm, indicates that both the Prescriptive VSWMR Alternative Liner and Proposed Alternative Bottom Liner yield less discharge than the Subtitle D liner Offices Nationwide

98 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY SCL DATE CCHECKED BY CJW DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

99 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

100 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

101 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

102 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

103 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

104 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

105 ATTACHMENT 2 Environmental Consultants & Contractors Midlothian Turnpike Suite 305 Midlothian, VA FAX JOB NO. SUBJECT PIPE CRUSHING ANALYSIS FEET SHOOSMITH SANITARY LANDFILL CCALCULATED BY CCHECKED BY SCL CJW DATE DATE 8/20/2015 8/21/2015 LFG HORIZONTAL COLLECTORS - PIPE CRUSHING ANALYSIS FEET Offices Nationwide

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