Stormwater Management Report

Transcription

1 Stormwater Management Report 20 Gorporate Drive Burlington, MA Submitted to: Town of Burlington July 22,20'16 þut

2 TABLE OF CONTENTS 1.0 INTRODUCTION STORMWATER MANAGEMENT Method of Calculations Rainfall Intensity Soil Conditions Detention Basin X and Y Storm Drainage System DEP STORMWATER STANDARDS Standard No. 1 Untreated Stormwater Standard No. 2 Post-development Peak Discharge Rates Standard No. 3 - Recharge to Groundwater Standard No. 4 - TSS Removal Street Sweeping Deep Sump/Hooded Catch Basins Stormceptor Treatment Unit Standard No. 5 - Higher Potential Pollutant Loads Standard No. 6 - Protection of Critical Areas Standard No. 7 - Redevelopment Projects Standard No. 8 - Erosion/Sediment Control Standard No. 9 - Operation/Maintenance Plan Standard No Illicit Discharge... 9 LIST OF TABLES Table 1: Storm Events Table 2: Impervious Area vs. Development Phase (Acres) Table 3: Planned Development (PD) District (Area A) i

3 LIST OF FIGURES Figure 1: Proposed Subcatchment Plan LIST OF APPENDICES Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Stormwater Checklist HydroCAD Report Groundwater Recharge Calculations Water Quality Calculations StormCAD Report Operations and Maintenance Plan Supporting Documentation ii

4 Stormwater Management Report 20 Corporate Drive, Burlington, MA 1.0 INTRODUCTION Tetra Tech has reviewed the hydrologic impacts associated with the proposed residential building constructed over a two (2) story parking garage at 20 Corporate Drive. The portions of the Burlington Centre Project constructed to date, including the overall drainage master plan, the specific work associated with Corporate Drive, the four existing buildings and the existing parking garage were approved by the Town of Burlington Planning Board and Conservation Commission. This residential development represents the last and final phase of the full build project. Drainage from the Maple Ridge residential areas was also constructed under the overall drainage master plan. The 20 Corporate Drive site consists of an existing surface parking lot, some steep wooded slopes, ledge outcrops and adjacent wetlands. A building at 88 Cambridge Street, located on the parcel, was demolished in 2005 to facilitate future construction on the lot. The new residential building at 20 Corporate Drive includes 271 residential units and a two-story parking garage with 402 parking spaces. There are also 14 surface parking spaces adjacent to the building. The new residential building will be accessed from Cambridge Street and Corporate Drive. The proposed residential project represents the construction of the fifth and final building (including parking garage under the building) within the Burlington Centre Office Park. The project as designed falls within the approved maximum impervious area limitations established under the 1987 Planned Development District (master plan full build design of Detention Basin X and Detention Basin Y ). Taking into account the proposed residential building, the overall contributing drainage area contains approximately 7% less impervious surface area than originally designed. The size of the existing detention facilities are essentially overdesigned and can accommodate the impervious area associated with the proposed residential development. The following report discusses in detail how Tetra Tech analyzed the drainage system with regard to compliance with the Stormwater Management standards for the proposed residential and parking garage as the last phase of the Burlington Centre project. Burlington Centre was originally approved under a Master Plan as a Planned Development District (PDD). As part of the Master Plan approval, a comprehensive stormwater management system was designed to provide best management practices to mitigation both stormwater quantity and quality impacts. The existing stormwater management system was designed to mitigate the construction of 26 acres of impervious surface for the full Burlington Centre buildout. At the completion of this project, which is considered the final phase of the Burlington Centre Project, the overall impervious coverage will be 22.4 acres, a reduction of 3.6 acres of impervious surface compared to the approved masterplan. Previous work associated with Corporate Drive and the first and second building (25 and 35 Corporate Drive) was approved by the Burlington Planning Board and the Burlington Conservation Commission under, DEQE File No Additionally, the third building (30 Corporate Drive) was previously approved under DEP File No The fourth building at 10 Corporate Drive was previously approved under DEP File No In terms of stormwater quantity, the existing stormwater management system consists of two detention basins located south of the project site (designed and constructed per the previously approved Full Build Hydrologic/Hydraulic Analysis [Appendix A, West Basin Volume 1 of 2, dated November, 1988 submitted by Daylor Consulting Group]). The basins were designed and approved as part of the larger Burlington Center Project full build out. Impervious surface associated with the proposed residential development was accounted for in terms of the basin volume sizing. Overall, the combined existing conditions and proposed new impervious surface will be less than the original full build out design. Therefore, the existing detention systems were designed and constructed to handle the flows from the new residential project. In terms of stormwater quality, all runoff from the residential development will be pretreated prior to discharge to the existing basins. Stormwater runoff from the residential project will be captured by a new 1

5 Stormwater Management Report 20 Corporate Drive, Burlington, MA system of catch basins equipped with hoods and deep sumps and routed to new stormceptor units prior to discharging off-site. The roof runoff will be captured internally and discharged to a subsurface infiltration system. The parking garage will be enclosed and the floor drains will be internal and routed to the sanitary sewer system. Runoff in contact with pollutants will be limited to the roadways to and from the highway and the 6 at-grade parking spaces in front of the building. All runoff from these areas will be pretreated prior to discharge to the existing detention basins. Given the existing, previously constructed stormwater management facilities were designed to accommodate flows from the new residential project, the hydrologic analysis included in this report focuses on sizing of a subsurface infiltration system, sized to provide groundwater recharge associated with the additional impervious cover proposed in conjunction with the residential project. 2.0 STORMWATER MANAGEMENT 2.1 METHOD OF CALCULATIONS The hydrologic and hydraulic model created to analyze the recharge system was developed by using the Soil Conservation Service (SCS) Technical Release No 20 (SCS unit hydrograph procedures), SCS Technical Release No. 55 (for Times of Concentration and Curve Numbers), SCS Technical Release No. 40 (for Rainfall Intensity) and the stormwater facilities were modeled using the Storage-Indication Method. The hydrologic model was created and calculated with HydroCAD, Version 10.0 software, developed by Applied Microcomputer Systems. The runoff from the sub-drainage areas (HydroCAD subcatchments) is calculated based on rainfall and the watershed characteristics, and a runoff hydrograph (a runoff rate versus time curve) is developed. The stage-storage-discharge curve for a specific detention area (i.e., an infiltration basin) is used to compute an outflow hydrograph by hydraulically routing an inflow hydrograph through the detention facilities. This procedure calculates the relationship of the inflow hydrograph with the characteristics of the detention basin systems to determine the outflow, stage, and storage capacity of the detention systems for a given time during the specified storm event. Pipe sizing calculations for the closed pipe drainage system were performed with StormCAD, a computer program by Haestad Methods, Inc., utilizing the Rational Method to determine the runoff. The Intensity Duration Frequency (IDF) Curves for the Boston area were used to obtain the rainfall intensity data for the hydraulic design standard 25-year storm event. Sources of Data SCS Technical Report No. 20 SCS Technical Report No. 55 SCS Technical Report No. 40 Soil Survey of Middlesex County, MA (Soil Conservation Service). Foundation Engineering Report prepared by McPhail Associates, LLC Full Build Analysis entitled, Appendix A Excerpts from Hydrologic/Hydraulic Calculations, West Basin, Burlington Centre, One Hundred Cambridge Street Volume 1 of 2, dated November, Site Development and Use Plans for Burlington Centre, One Hundred Cambridge Street, and Site Plans for Cambridge Street Burlington, MA, prepared by Daylor Consulting Group, Inc. dated July 29,

6 Stormwater Management Report 20 Corporate Drive, Burlington, MA Site Development and Use Plan for Burlington Centre, (Building III) Burlington Center Corporate Drive prepared by Daylor Consulting Group, Inc., dated July 29, 1999, revised to March 27, Stormwater Management Report for Building 100, Burlington Centre, Burlington MA prepared by Daylor Consulting Group, Inc, dated November 16, RAINFALL INTENSITY In accordance with the Massachusetts Department of Environmental Protection guidelines, the one, ten, and one-hundred year storm events were analyzed. The following are the rainfall intensities used for each storm event. Table 1: Storm Events Storm Event 24 Hour Rainfall 1 year 2.70 inches 10 year 4.60 inches 100 year 6.75 inches Above values were taken from previous design data Appendix A - Excerpts from Hydrologic/Hydraulic Calculations, Volume 1 of 2, November 1988". 2.3 SOIL CONDITIONS The United States Department of Agriculture, Middlesex County (Map 31) Soil Conservation Service (SCS) has conducted a soil survey of Burlington, Massachusetts identifying the various soil types throughout the proposed development. The area consists of soil type: Chatfield-Hollis-Rock Outcrop Complex 8C, 8D (hydrologic soil group C/D) and Swansea Muck 45 (hydrologic soil group D). In addition to the SCS mapping, a geotechnical investigation was undertaken. Recommendations from the investigation indicate on-site soils are consistent with hydrological soil group B and that should be the basis of the design for on-site groundwater recharge. A copy of the geotechnical recommendations can be found in Appendix G. 2.4 DETENTION BASIN X AND Y Previous work approved by the Planning Board and the Conservation Commission included the construction of two stormwater detention facilities, Detention Facilities X and Y, based on the 1, 10 and 100 year storm events. As indicated in the previously approved Full Build Hydrologic Analysis, these stormwater detention areas are designed to accommodate the runoff from the full park build out, including the first four buildings, parking garages and surface parking from the final (5 th ) stage of development of the office park. The design and calculations for sizing the system follow the procedures outlined in DEP S Stormwater Policy Handbook.. 3

7 Stormwater Management Report 20 Corporate Drive, Burlington, MA The following data was previously submitted to the Planning Board and Conservation Commission for the construction of 25, 30 and 35 Corporate Drive and an accessory parking garage: Drainage Report, Appendix A - Hydrologic/Hydraulic Analysis Volume 1of 2, dated November Application for Special Permit, dated July 7, 1995, Phase II. Notice of Intent, Phase II, dated July 7, 1995". Notice of Intent, Cambridge Street, 200 & 300 Burlington Centre, dated July 29, 1999 and revised October 15, The existing detention facilities will effectively mitigate stormwater impacts associated with the residential project. The stormwater management system was designed and constructed under the previous design analysis and included all proposed new impervious area, including the proposed building at the residential project site. The two detention basins, X and Y, which drain to a wetland at the southern boundary of the site, were originally designed and approved to accommodate the runoff from the lot which at the time was designed to be an office building with structured parking facilities. The Burlington Centre Office Park calculations for detention facilities X and Y demonstrate that the basins have sufficient capacity in terms of storage volume to accommodate the final phase. Table 2 lists the total impervious areas for the previously approved office development, the existing impervious areas approved for the three existing buildings and garage, and the proposed impervious areas associated with the residential project at 20 Corporate Drive. As shown in Table 2, the impervious areas total for the existing Corporate Center combined with the proposed residential development, will be less than originally designed, therefore, the existing detention facilities can accommodate the design flows associated with the new project. Table 2: Impervious Area vs. Development Phase (Acres) Previously Approved Existing Acres of Acres of Impervious Impervious Area Area for Office Development Proposed Acres of Impervious Area following Completion of Building-20 Corporate Pond X 4.5* 3.4** 4.3 Pond Y 6.8* 6.3** 6.3 *Allowed impervious from 1986 approval. **Above data from Application for Special Permit, Phase II, July 7, 1995, page STORM DRAINAGE SYSTEM The storm drain pipes were sized using the Rational Method and Manning Equation with the aid of Stormcad Software (Haestad Methods). See Appendix E for the calculations. The proposed system, in keeping with the previously constructed drainage system, will have deep sump, hooded catch basins that will remove and retain suspended solids within the catch basins. The existing oil/water separators on site were sized to handle full build out including the proposed residential development, and therefor adequately sized to handle additional flows prior to discharging to the detention basins. 4

8 Stormwater Management Report 20 Corporate Drive, Burlington, MA In addition to the existing oil/water separators, a new Stormceptors will be installed prior to connecting to drain systems as shown on Sheet 6, Grading & Drainage Plan. This will allow settlement of suspended solids prior to discharge to detention basins or off-site systems. 3.0 DEP STORMWATER STANDARDS The purpose of the Stormwater Management Plan is to provide a comprehensive framework for the longterm protection of natural resources in and around the Site from degradation as a result of stormwater discharges. This is achieved through the use of a variety of water quality and quantity control measures designed to decrease the amount of pollutants discharged from the Site and control discharge rates and volumes. Burlington Centre was originally approved under a Master Plan as a Planned Development District. As part of the Master Plan approval, a comprehensive stormwater management system was designed to provide best management practices to mitigation both stormwater quantity and quality impacts. The existing stormwater management system was designed to mitigate the introduction of 26 acres of impervious surface for the full Burlington Centre buildout. At the completion of this project, which is considered the final phase of the Burlington Centre Project, the overall impervious coverage will be 23.5 acres, a reduction of 2.5 acres of impervious surface. In terms of quantity, the existing stormwater management system consists of two detention basins located south of the project site. The basins were designed and approved as part of the larger Burlington Center Project full build out. Impervious surface associated with the proposed residential development was accounted for in terms of the basin volume sizing. Overall, the combined existing conditions and proposed new impervious surface will be less than the original full build out design. Therefore, the existing detention systems were sized to handle the flows from the residential project. In terms of quality, all runoff from the residential development will be pretreated prior to discharge to the existing basins. Stormwater runoff from the residential project will be captured by a new system of catch basins equipped with hoods and deep sumps, routed to existing oil/water separators (sized to include the full build out) and also to one new stormceptor unit in a location where routing to an existing treatment structure was not possible. The roof runoff will be captured internally and discharged to a subsurface infiltration system. The parking garage will be enclosed and the floor drains will be internal and routed to the sewer system. Runoff in contact with pollutants will be limited to the roadways to and from the highway and the 6 at-grade parking spaces in front of the building. All runoff from these areas will be pretreated prior to discharge to the existing detention basins. The ten standards contained in the DEP Stormwater Management Standards relate to the protection of wetlands and water bodies, control of water quantity, recharge to groundwater, water quality and protection of critical areas, erosion/sedimentation control and stormwater maintenance. The following sections describe the regulations pertinent to stormwater management and the specific components of the Stormwater Management Plan to be implemented at the Site. 5

9 3.1 STANDARD NO. 1 UNTREATED STORMWATER Stormwater Management Report 20 Corporate Drive, Burlington, MA No new point discharges of untreated stormwater to resource areas are proposed. Proposed stormwater quality control improvements for the project includes street sweeping, deep sump/hooded catch basins, and Stormceptor treatment units. 3.2 STANDARD NO. 2 POST-DEVELOPMENT PEAK DISCHARGE RATES Stormwater management systems shall be designed so that post development peak discharge rates do not exceed pre-development discharge rates. The peak runoff flows were conservatively estimated for the pre-development and the post-development conditions for the Full Build design. The developed site flows will be less or equal to peak flows predicted for the full development conditions as outlined in Application for Special Permit, Notice of Intent, Phase II, July 7, 1995 and Appendix A, Hydrologic/Hydraulic Calculations, Vol. 1of 2, Nov Additionally, the proposed residential building with parking below, surface parking, walkways and other impervious landscape features in regards to the dimensional requirements for Planned Development (PD) District (Area A) do not exceed the allowable impervious ratio limitations as shown in Table 3 below. Table 3: Planned Development (PD) District (Area A) Maximum Permitted by Concept Plan Existing Conditions Proposed Conditions Total Land Area ac n/a n/a Site Coverage of Buildings Area Covered By Impervious Surface Building Surface Area Ratio 8.25 ac 5.41 ac 7.23 ac 26.0 ac ac ac 11.7% 7.0% 9.4% Impervious Surface 33.7% 26.0% 29.1% The proposed residential building parking below, surface parking, walkways and other impervious landscape features do not exceed the allowable impervious ratio limitations established as the design basis for the full build design. The full build out was approved for 33.7% impervious surface, while the residential development will increase existing conditions (26%) by 3.1% to 29.1%, below the maximum designed system for full build out in terms of peak rates. 3.3 STANDARD NO. 3 - RECHARGE TO GROUNDWATER A Recharge System has been designed to provide infiltration of roof runoff to groundwater and further attenuate the post development peak rates of stormwater runoff. Stormwater runoff from the building roof will be collected and routed to the recharge system. The recharge system has been designed with an 6

10 Stormwater Management Report 20 Corporate Drive, Burlington, MA infiltration rate of 1.02 inches per hour based on DEP Stormwater Management Standards for Sandy Loam soils, refer to Foundation Engineering Report provided in Appendix G. The Recharge System consist of a series of chambers surrounded with drain rock and filter fabric. The bottom of Recharge System will be a minimum of 2-feet above the estimated seasonal high groundwater table. The outlet control structure has been designed with a weir elevation that provides for acre feet of static storage (0.070 acre feet required). The static storage volume will be completely infiltrated within 20.5 hours. Refer to Appendix C for Groundwater Recharge Calculations. 3.4 STANDARD NO. 4 - TSS REMOVAL Best Management Practices (BMPs) will be used to provide water quality. The following proposed BMPs will be provided on-site to treat the impervious area on site: street sweeping, deep sump/hooded catch basins, and Stormceptor treatment units. Additionally, existing BMP s designed and installed in previous phases will also provide treatment to impervious areas: oil/grit separators and extended dry detention basins. In terms of quality, the runoff exceeds the minimum 80% TSS removal rate required by the Massachusetts DEP Stormwater Standards by providing a range between 82% and 87% TSS removal, depending on the point of discharge. The TSS removal rate is achieved through the implementation of Best Management Practices (BMPs) to treat the impervious area on site: street sweeping, deep sump/hooded catch basins, and Stormceptor treatment unit. Additionally, existing BMP s designed and installed in previous phases will also provide treatment to impervious areas: oil/grit separators and extended dry detention basins Street Sweeping The proposed design incorporates street sweeping as a BMP to control the amount of sediment that enters the drainage system. Street sweeping will be conducted on a quarterly average and be primarily scheduled in the spring and fall. In accordance with DEP Standards a 5% total suspended solids (TSS) removal rate is credited for this BMP Deep Sump/Hooded Catch Basins All proposed catch basins will be deep sump/hooded catch basins, which will serve to trap sediment and floatables before entering the stormwater management system. Sumps will be four-feet deep. Catch basins will be inspected quarterly and, if necessary, cleaned when sediment reaches half full depth to ensure that the catch basins are working in their intended fashion and that they are free of debris. Sediments and hydrocarbons shall be properly handled and disposed of, in accordance with local, state, and federal requirements. All catch basins will be installed with sediment sumps and oil hoods. In accordance with DEP Standards a 25% total suspended solids (TSS) removal rate is credited for this BMP Stormceptor Treatment Unit The proposed design of the on-site drainage system will incorporate new Stormceptor units prior to discharging to the existing drainage stystem. 7

11 Stormwater Management Report 20 Corporate Drive, Burlington, MA In accordance with DEP Standards the MASTEP laboratory study found the Stormceptor STC 900 achieved 75% removal of Bulk TSS, which MASTEP considers equivalent to suspended sediment concentration (SSC). While this information references the STC 900, the performance of the structures can be scaled upward or downward based on the size of the units, and areas and flows to be treated. The TSS Removal Calculations in Appendix D are representative of the MASTEP 75% removal rate. However, according to the Stormceptor sizing program based upon independent test data, the Stormceptor structures specified on the plans will achieve TSS removal rates in excess of 75%. Refer to Appendix D for Water Quality Structure Efficiency Calculations. Although redevelopment projects are not required to achieve 80% removal of TSS, the incorporation of these BMPs will achieve a cumulative TSS removal rate of greater than 80%. Refer to Appendix D for Water Quality Calculations and a copy of the MASTEP Report. 3.5 STANDARD NO. 5 - HIGHER POTENTIAL POLLUTANT LOADS Although the project will generate more than 1,000 trips per day, the high intensity use will be limited in that stormwater discharges will not come into contact with the parking areas associated with the trips because it will be inside of the garage, where any discharges will be routed to the sewer system. Because the land use associated with the parking area generating the 1,000 trips per day will not come in contact with precipitation, the site will not generate a higher potential pollutant load, therefore, further treatment of runoff is unnecessary. 3.6 STANDARD NO. 6 - PROTECTION OF CRITICAL AREAS There are restrictions for discharges to Critical Areas, such as Outstanding Resource Waters (ORWs), shellfish beds, swimming beaches, cold water fisheries, and recharge areas for public drinking water supplies. The project site is not discharging to a critical area. 3.7 STANDARD NO. 7 - REDEVELOPMENT PROJECTS Redevelopment projects include development, rehabilitation, expansion and phased projects on previously developed sites, provided the redevelopment results in no net increase in impervious area. A portion of the project qualifies as redevelopment since it constitutes a phased project on a previously developed site. Portions of it qualify as new development since it will result in an increase in the amount of impervious surface. As such, the proposed Project qualifies as a redevelopment project and is required to meet the following Stormwater Management Standards to the maximum extent practicable: Standard 2 and 3, and the pretreatment and structural best management practice requirements of Standards 4, 5, and 6. Although portions of the project qualify as redevelopment, the project was designed to meet all standards to the level of a new project and not just to the extent practicable. 3.8 STANDARD NO. 8 - EROSION/SEDIMENT CONTROL The Project will result in the disturbance of greater than one (1) acre of land, a Storm Water Pollution Prevention Plan (SWPPP) will be prepared in accordance with the EPA NPDES General Permit for Discharges from Construction Activities, effective date February 16, A Notice of Intent will be submitted to the EPA prior to commencement of construction activities to obtain coverage under the Construction General Permit.. 8

12 Stormwater Management Report 20 Corporate Drive, Burlington, MA The SWPPP will be prepared describing the specific practices, installation methods and inspection requirements for temporary and permanent erosion prevention and sediment control practices. The SWPPP will follow the template developed by the U.S. EPA and filed with the Burlington Conservation Commission. Sequencing plans and details of erosion prevention and sediment control measures are provided in the Plan set At a minimum, the SWPPP will include the following measures: Minimize the extent and time of exposed soils; Provide perimeter sediment control including compost filter tubes; Provide catch basin inlet protection including geotextile filter fabric and gravel drop; Minimize sediment track out with stabilized construction exits; Dedicated concrete washout areas; Control discharges from soil stockpiles include temporary erosion control measures and perimeter sediment controls; Minimize dust and soil compaction; Temporary stormwater management practices including basins, traps and swales; Dewatering requirements; Temporary and permanent stabilization requirements, including seeding, mulching and matting; Good housekeeping pollution prevention measures; Maintenance requirements; and Inspection, recordkeeping, and reporting requirements 3.9 STANDARD NO. 9 - OPERATION/MAINTENANCE PLAN The Stormwater Management System will be the overall responsibility of the Owner. An Operations and Maintenance Plan is included in Appendix F STANDARD NO ILLICIT DISCHARGE To the best of the owner s and engineer s knowledge, no illicit discharges exist on Site and no illicit discharges will be incorporated as part of the proposed redevelopment Project into the proposed stormwater management system. 9

13 /20/2016 2:36:34 PM - P:\104275\ \CAD\SUPPORTFILES\DRAINAGE\FIGURE 1-SUBCATCMENT PLAN.DWG - VOLPICELLI, MIRANDA F E D C B A SEE SHEET C xx xx xx SD SD 222 CB o o o o o o o o o o o o 218 CB RESTORATION AREA 3,300 S.F. (SEE LANDSCAPE PLANS) o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o SD o o o o o o o o o 214 o o o MEP MEP 213 o o o o CB COURTYARD 3 F.G. =236.5± CY TRASH / LOADING W/ BOWLING ALLEY ABOVE CB LIMIT OF PREVIOUSLY DISTURBED AREA ROOF 217 PARKING BELOW RESIDENTIAL STRUCTURE PARKING LEVEL 1 GFE=214.5 PARKING LEVEL 2 GFE=225.5 CY 2 COURTYARD 2 F.G.=236.5± RAMP DOWN LIMIT OF PREVIOUSLY DISTURBED AREA LOBBY COURTYARD 1 F.G.=236.5± CY 1 POOL AREA DOMINATED BY PINE TREES (NON-DECIDUOUS) BIKE STORAGE / DOG WASH 1,800 SF MEP :1 SLOPE N 0 20' 40' 80' SCALE: 1" = 40' MARK DATE DESCRIPTION BY Site Development Plans The Residences at Burlington Centre, Burlington MA Proposed Subcatchment Plan 100 Nickerson Road Marlborough, MA PHONE: (508) FAX: (508) Copyright: Tetra Tech Bar Measures 1 inch

14 Appendix A Stormwater Checklist

15 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include: The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals. 1 This Checklist is to be used as the cover for the completed Stormwater Report. Applicant/Project Name Project Address Name of Firm and Registered Professional Engineer that prepared the Report Long-Term Pollution Prevention Plan required by Standards 4-6 Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 8 2 Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. 1 The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. 2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. swcheck.doc 04/01/08 Stormwater Report Checklist Page 1 of 8

16 EI Massach usetts Depa rtment of E nvi ron mental P rotection Bureau of Resource Protection - Wetlands Program Ghecklist for Stormwater Report B. Stormwater Ghecklist and Gertification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Nofe: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. lf it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.4.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Profess ona Engineer's Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Longterm Post-Construction Operation and Maintenance Plan, the lllicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature NATHAN H. CHEAL NO CIVIL and t Ghecklist Project Type: ls the application for new development, redevelopment, or a mix of new and redevelopment? E trtew development n Redevelopment X lt x of New Development and Redevelopment swcheck.doc Stormwater Report Checklist. Page 2 of I

17 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: No disturbance to any Wetland Resource Areas Site Design Practices (e.g. clustered development, reduced frontage setbacks) Reduced Impervious Area (Redevelopment Only) Minimizing disturbance to existing trees and shrubs LID Site Design Credit Requested: Credit 1 Credit 2 Credit 3 Use of country drainage versus curb and gutter conveyance and pipe Bioretention Cells (includes Rain Gardens) Constructed Stormwater Wetlands (includes Gravel Wetlands designs) Treebox Filter Water Quality Swale Grass Channel Green Roof Other (describe): Standard 1: No New Untreated Discharges No new untreated discharges Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. swcheck.doc 04/01/08 Stormwater Report Checklist Page 3 of 8

18 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. Calculations provided to show that post-development peak discharge rates do not exceed predevelopment rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24- hour storm. Standard 3: Recharge Soil Analysis provided. Required Recharge Volume calculation provided. Required Recharge volume reduced through use of the LID site Design Credits. Sizing the infiltration, BMPs is based on the following method: Check the method used. Static Simple Dynamic Dynamic Field 1 Runoff from all impervious areas at the site discharging to the infiltration BMP. Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: Site is comprised solely of C and D soils and/or bedrock at the land surface M.G.L. c. 21E sites pursuant to 310 CMR Solid Waste Landfill pursuant to 310 CMR Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. Calculations showing that the infiltration BMPs will drain in 72 hours are provided. Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included. 1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. swcheck.doc 04/01/08 Stormwater Report Checklist Page 4 of 8

19 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following: Good housekeeping practices; Provisions for storing materials and waste products inside or under cover; Vehicle washing controls; Requirements for routine inspections and maintenance of stormwater BMPs; Spill prevention and response plans; Provisions for maintenance of lawns, gardens, and other landscaped areas; Requirements for storage and use of fertilizers, herbicides, and pesticides; Pet waste management provisions; Provisions for operation and management of septic systems; Provisions for solid waste management; Snow disposal and plowing plans relative to Wetland Resource Areas; Winter Road Salt and/or Sand Use and Storage restrictions; Street sweeping schedules; Provisions for prevention of illicit discharges to the stormwater management system; Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: is within the Zone II or Interim Wellhead Protection Area is near or to other critical areas is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) involves runoff from land uses with higher potential pollutant loads. The Required Water Quality Volume is reduced through use of the LID site Design Credits. Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided. swcheck.doc 04/01/08 Stormwater Report Checklist Page 5 of 8

20 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) The BMP is sized (and calculations provided) based on: The ½ or 1 Water Quality Volume or The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs. A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs. The NPDES Multi-Sector General Permit does not cover the land use. LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. All exposure has been eliminated. All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. Critical areas and BMPs are identified in the Stormwater Report. swcheck.doc 04/01/08 Stormwater Report Checklist Page 6 of 8

21 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: Limited Project Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area. Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff Bike Path and/or Foot Path Redevelopment Project Redevelopment portion of mix of new and redevelopment. Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: Narrative; Construction Period Operation and Maintenance Plan; Names of Persons or Entity Responsible for Plan Compliance; Construction Period Pollution Prevention Measures; Erosion and Sedimentation Control Plan Drawings; Detail drawings and specifications for erosion control BMPs, including sizing calculations; Vegetation Planning; Site Development Plan; Construction Sequencing Plan; Sequencing of Erosion and Sedimentation Controls; Operation and Maintenance of Erosion and Sedimentation Controls; Inspection Schedule; Maintenance Schedule; Inspection and Maintenance Log Form. A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. swcheck.doc 04/01/08 Stormwater Report Checklist Page 7 of 8

22 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. The project is not covered by a NPDES Construction General Permit. The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: Name of the stormwater management system owners; Party responsible for operation and maintenance; Schedule for implementation of routine and non-routine maintenance tasks; Plan showing the location of all stormwater BMPs maintenance access areas; Description and delineation of public safety features; Estimated operation and maintenance budget; and Operation and Maintenance Log Form. The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: A copy of the legal instrument (deed, homeowner s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; An Illicit Discharge Compliance Statement is attached; NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. swcheck.doc 04/01/08 Stormwater Report Checklist Page 8 of 8

23 Appendix B HydroCAD Report

24 Roof 1P StormTech Pipe EDB Exist. 30" POA 1 Subcat Reach Pond Link Routing Diagram for Proposed Drainage Conditons_SC740_Rev Rain Prepared by Tetra Tech Inc., Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC

25 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Prepared by Tetra Tech Inc. HydroCAD s/n HydroCAD Software Solutions LLC Printed 6/23/2016 Page 2 Area (acres) CN Description (subcatchment-numbers) Roofs, HSG A (Roof) TOTAL AREA Area Listing (all nodes)

26 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 2-Year Rainfall=3.20" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 3 Time span= hrs, dt=0.01 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind method - Pond routing by Stor-Ind method Subcatchment Roof: Runoff Area=59,635 sf % Impervious Runoff Depth>2.97" Tc=5.0 min CN=98 Runoff=4.41 cfs af Reach Pipe: Exist. 30" Avg. Flow Depth=0.44' Max Vel=7.43 fps Inflow=4.30 cfs af 30.0" Round Pipe n=0.015 L=237.0' S= '/' Capacity=64.24 cfs Outflow=4.28 cfs af Pond 1P: StormTech Link EDB: POA 1 Peak Elev=217.20' Storage=3,443 cf Inflow=4.41 cfs af Discarded=0.04 cfs af Primary=4.30 cfs af Outflow=4.34 cfs af Inflow=4.28 cfs af Primary=4.28 cfs af Total Runoff Area = ac Runoff Volume = af Average Runoff Depth = 2.97" 0.00% Pervious = ac % Impervious = ac

27 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 2-Year Rainfall=3.20" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment Roof: Runoff = hrs, Volume= af, Depth> 2.97" Runoff by SCS TR-20 method, UH=SCS, Time Span= hrs, dt= 0.01 hrs Type III 24-hr 2-Year Rainfall=3.20" Area (sf) CN Description 59, Roofs, HSG A 59, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, [52] Hint: Inlet/Outlet conditions not evaluated Summary for Reach Pipe: Exist. 30" Inflow Area = ac,100.00% Impervious, Inflow Depth = 1.71" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.4 min Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs / 2 Max. Velocity= 7.43 fps, Min. Travel Time= 0.5 min Avg. Velocity = 2.22 fps, Avg. Travel Time= 1.8 min Peak Storage= hrs Average Depth at Peak Storage= 0.44' Bank-Full Depth= 2.50' Flow Area= 4.9 sf, Capacity= cfs 30.0" Round Pipe n= Concrete sewer w/manholes & inlets Length= 237.0' Slope= '/' Inlet Invert= ', Outlet Invert= ' Summary for Pond 1P: StormTech Inflow Area = ac,100.00% Impervious, Inflow Depth > 2.97" for 2-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 1%, Lag= 0.8 min Discarded = hrs, Volume= af Primary = hrs, Volume= af

28 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 2-Year Rainfall=3.20" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 5 Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,782 sf Storage= 3,443 cf Plug-Flow detention time= min calculated for af (79% of inflow) Center-of-Mass det. time= 38.6 min ( ) Volume Invert Avail.Storage Storage Description #1A ' 1,405 cf 30.00'W x 59.40'L x 3.50'H Field A 6,237 cf Overall - 2,222 cf Embedded = 4,015 cf x 35.0% Voids #2A ' 2,222 cf ADS_StormTech SC-740 x 48 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows 3,627 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary ' 24.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.012, Flow Area= 3.14 sf #2 Device ' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #3 Discarded ' in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 0.00' Discarded OutFlow Max= hrs HW=217.20' (Free Discharge) 3=Exfiltration ( Controls 0.04 cfs) Primary OutFlow Max= hrs HW=217.20' (Free Discharge) 1=Culvert (Passes 4.29 cfs of cfs potential flow) 2=Broad-Crested Rectangular Weir (Weir Controls fps) Summary for Link EDB: POA 1 Inflow Area = ac,100.00% Impervious, Inflow Depth = 1.71" for 2-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

29 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 10-Year Rainfall=4.60" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 6 Time span= hrs, dt=0.01 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind method - Pond routing by Stor-Ind method Subcatchment Roof: Runoff Area=59,635 sf % Impervious Runoff Depth>4.36" Tc=5.0 min CN=98 Runoff=6.38 cfs af Reach Pipe: Exist. 30" Avg. Flow Depth=0.53' Max Vel=8.30 fps Inflow=6.27 cfs af 30.0" Round Pipe n=0.015 L=237.0' S= '/' Capacity=64.24 cfs Outflow=6.25 cfs af Pond 1P: StormTech Link EDB: POA 1 Peak Elev=217.33' Storage=3,523 cf Inflow=6.38 cfs af Discarded=0.04 cfs af Primary=6.27 cfs af Outflow=6.31 cfs af Inflow=6.25 cfs af Primary=6.25 cfs af Total Runoff Area = ac Runoff Volume = af Average Runoff Depth = 4.36" 0.00% Pervious = ac % Impervious = ac

30 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 10-Year Rainfall=4.60" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment Roof: Runoff = hrs, Volume= af, Depth> 4.36" Runoff by SCS TR-20 method, UH=SCS, Time Span= hrs, dt= 0.01 hrs Type III 24-hr 10-Year Rainfall=4.60" Area (sf) CN Description 59, Roofs, HSG A 59, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, [52] Hint: Inlet/Outlet conditions not evaluated Summary for Reach Pipe: Exist. 30" Inflow Area = ac,100.00% Impervious, Inflow Depth > 3.06" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.3 min Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs / 2 Max. Velocity= 8.30 fps, Min. Travel Time= 0.5 min Avg. Velocity = 2.68 fps, Avg. Travel Time= 1.5 min Peak Storage= hrs Average Depth at Peak Storage= 0.53' Bank-Full Depth= 2.50' Flow Area= 4.9 sf, Capacity= cfs 30.0" Round Pipe n= Concrete sewer w/manholes & inlets Length= 237.0' Slope= '/' Inlet Invert= ', Outlet Invert= ' Summary for Pond 1P: StormTech Inflow Area = ac,100.00% Impervious, Inflow Depth > 4.36" for 10-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 1%, Lag= 0.6 min Discarded = hrs, Volume= af Primary = hrs, Volume= af

31 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 10-Year Rainfall=4.60" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 8 Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,782 sf Storage= 3,523 cf Plug-Flow detention time= min calculated for af (86% of inflow) Center-of-Mass det. time= 37.3 min ( ) Volume Invert Avail.Storage Storage Description #1A ' 1,405 cf 30.00'W x 59.40'L x 3.50'H Field A 6,237 cf Overall - 2,222 cf Embedded = 4,015 cf x 35.0% Voids #2A ' 2,222 cf ADS_StormTech SC-740 x 48 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows 3,627 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary ' 24.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.012, Flow Area= 3.14 sf #2 Device ' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #3 Discarded ' in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 0.00' Discarded OutFlow Max= hrs HW=217.33' (Free Discharge) 3=Exfiltration ( Controls 0.04 cfs) Primary OutFlow Max= hrs HW=217.33' (Free Discharge) 1=Culvert (Passes 6.27 cfs of cfs potential flow) 2=Broad-Crested Rectangular Weir (Weir Controls fps) Summary for Link EDB: POA 1 Inflow Area = ac,100.00% Impervious, Inflow Depth > 3.06" for 10-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

32 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 25-Year Rainfall=5.50" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 9 Time span= hrs, dt=0.01 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind method - Pond routing by Stor-Ind method Subcatchment Roof: Runoff Area=59,635 sf % Impervious Runoff Depth>5.26" Tc=5.0 min CN=98 Runoff=7.64 cfs af Reach Pipe: Exist. 30" Avg. Flow Depth=0.58' Max Vel=8.75 fps Inflow=7.54 cfs af 30.0" Round Pipe n=0.015 L=237.0' S= '/' Capacity=64.24 cfs Outflow=7.51 cfs af Pond 1P: StormTech Link EDB: POA 1 Peak Elev=217.40' Storage=3,567 cf Inflow=7.64 cfs af Discarded=0.04 cfs af Primary=7.54 cfs af Outflow=7.58 cfs af Inflow=7.51 cfs af Primary=7.51 cfs af Total Runoff Area = ac Runoff Volume = af Average Runoff Depth = 5.26" 0.00% Pervious = ac % Impervious = ac

33 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 25-Year Rainfall=5.50" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment Roof: Runoff = hrs, Volume= af, Depth> 5.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= hrs, dt= 0.01 hrs Type III 24-hr 25-Year Rainfall=5.50" Area (sf) CN Description 59, Roofs, HSG A 59, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, [52] Hint: Inlet/Outlet conditions not evaluated Summary for Reach Pipe: Exist. 30" Inflow Area = ac,100.00% Impervious, Inflow Depth > 3.95" for 25-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.3 min Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs / 2 Max. Velocity= 8.75 fps, Min. Travel Time= 0.5 min Avg. Velocity = 2.92 fps, Avg. Travel Time= 1.4 min Peak Storage= hrs Average Depth at Peak Storage= 0.58' Bank-Full Depth= 2.50' Flow Area= 4.9 sf, Capacity= cfs 30.0" Round Pipe n= Concrete sewer w/manholes & inlets Length= 237.0' Slope= '/' Inlet Invert= ', Outlet Invert= ' Summary for Pond 1P: StormTech Inflow Area = ac,100.00% Impervious, Inflow Depth > 5.26" for 25-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 1%, Lag= 0.6 min Discarded = hrs, Volume= af Primary = hrs, Volume= af

34 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 25-Year Rainfall=5.50" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 11 Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,782 sf Storage= 3,567 cf Plug-Flow detention time= 92.4 min calculated for af (88% of inflow) Center-of-Mass det. time= 36.4 min ( ) Volume Invert Avail.Storage Storage Description #1A ' 1,405 cf 30.00'W x 59.40'L x 3.50'H Field A 6,237 cf Overall - 2,222 cf Embedded = 4,015 cf x 35.0% Voids #2A ' 2,222 cf ADS_StormTech SC-740 x 48 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows 3,627 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary ' 24.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.012, Flow Area= 3.14 sf #2 Device ' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #3 Discarded ' in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 0.00' Discarded OutFlow Max= hrs HW=217.40' (Free Discharge) 3=Exfiltration ( Controls 0.04 cfs) Primary OutFlow Max= hrs HW=217.40' (Free Discharge) 1=Culvert (Passes 7.53 cfs of cfs potential flow) 2=Broad-Crested Rectangular Weir (Weir Controls fps) Summary for Link EDB: POA 1 Inflow Area = ac,100.00% Impervious, Inflow Depth > 3.95" for 25-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

35 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 50-Year Rainfall=6.10" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 12 Time span= hrs, dt=0.01 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind method - Pond routing by Stor-Ind method Subcatchment Roof: Runoff Area=59,635 sf % Impervious Runoff Depth>5.86" Tc=5.0 min CN=98 Runoff=8.48 cfs af Reach Pipe: Exist. 30" Avg. Flow Depth=0.61' Max Vel=9.03 fps Inflow=8.38 cfs af 30.0" Round Pipe n=0.015 L=237.0' S= '/' Capacity=64.24 cfs Outflow=8.35 cfs af Pond 1P: StormTech Link EDB: POA 1 Peak Elev=217.45' Storage=3,594 cf Inflow=8.48 cfs af Discarded=0.04 cfs af Primary=8.38 cfs af Outflow=8.42 cfs af Inflow=8.35 cfs af Primary=8.35 cfs af Total Runoff Area = ac Runoff Volume = af Average Runoff Depth = 5.86" 0.00% Pervious = ac % Impervious = ac

36 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 50-Year Rainfall=6.10" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 13 Summary for Subcatchment Roof: Runoff = hrs, Volume= af, Depth> 5.86" Runoff by SCS TR-20 method, UH=SCS, Time Span= hrs, dt= 0.01 hrs Type III 24-hr 50-Year Rainfall=6.10" Area (sf) CN Description 59, Roofs, HSG A 59, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, [52] Hint: Inlet/Outlet conditions not evaluated Summary for Reach Pipe: Exist. 30" Inflow Area = ac,100.00% Impervious, Inflow Depth > 4.54" for 50-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.3 min Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs / 2 Max. Velocity= 9.03 fps, Min. Travel Time= 0.4 min Avg. Velocity = 3.06 fps, Avg. Travel Time= 1.3 min Peak Storage= hrs Average Depth at Peak Storage= 0.61' Bank-Full Depth= 2.50' Flow Area= 4.9 sf, Capacity= cfs 30.0" Round Pipe n= Concrete sewer w/manholes & inlets Length= 237.0' Slope= '/' Inlet Invert= ', Outlet Invert= ' Summary for Pond 1P: StormTech Inflow Area = ac,100.00% Impervious, Inflow Depth > 5.86" for 50-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 1%, Lag= 0.5 min Discarded = hrs, Volume= af Primary = hrs, Volume= af

37 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 50-Year Rainfall=6.10" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 14 Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,782 sf Storage= 3,594 cf Plug-Flow detention time= 88.0 min calculated for af (89% of inflow) Center-of-Mass det. time= 35.7 min ( ) Volume Invert Avail.Storage Storage Description #1A ' 1,405 cf 30.00'W x 59.40'L x 3.50'H Field A 6,237 cf Overall - 2,222 cf Embedded = 4,015 cf x 35.0% Voids #2A ' 2,222 cf ADS_StormTech SC-740 x 48 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows 3,627 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary ' 24.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.012, Flow Area= 3.14 sf #2 Device ' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #3 Discarded ' in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 0.00' Discarded OutFlow Max= hrs HW=217.45' (Free Discharge) 3=Exfiltration ( Controls 0.04 cfs) Primary OutFlow Max= hrs HW=217.45' (Free Discharge) 1=Culvert (Passes 8.37 cfs of cfs potential flow) 2=Broad-Crested Rectangular Weir (Weir Controls fps) Summary for Link EDB: POA 1 Inflow Area = ac,100.00% Impervious, Inflow Depth > 4.54" for 50-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

38 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 100-Year Rainfall=6.75" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 15 Time span= hrs, dt=0.01 hrs, 2401 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind method - Pond routing by Stor-Ind method Subcatchment Roof: Runoff Area=59,635 sf % Impervious Runoff Depth>6.51" Tc=5.0 min CN=98 Runoff=9.39 cfs af Reach Pipe: Exist. 30" Avg. Flow Depth=0.64' Max Vel=9.30 fps Inflow=9.29 cfs af 30.0" Round Pipe n=0.015 L=237.0' S= '/' Capacity=64.24 cfs Outflow=9.25 cfs af Pond 1P: StormTech Link EDB: POA 1 Peak Elev=217.49' Storage=3,622 cf Inflow=9.39 cfs af Discarded=0.04 cfs af Primary=9.29 cfs af Outflow=9.33 cfs af Inflow=9.25 cfs af Primary=9.25 cfs af Total Runoff Area = ac Runoff Volume = af Average Runoff Depth = 6.51" 0.00% Pervious = ac % Impervious = ac

39 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 100-Year Rainfall=6.75" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 16 Summary for Subcatchment Roof: Runoff = hrs, Volume= af, Depth> 6.51" Runoff by SCS TR-20 method, UH=SCS, Time Span= hrs, dt= 0.01 hrs Type III 24-hr 100-Year Rainfall=6.75" Area (sf) CN Description 59, Roofs, HSG A 59, % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, [52] Hint: Inlet/Outlet conditions not evaluated Summary for Reach Pipe: Exist. 30" Inflow Area = ac,100.00% Impervious, Inflow Depth > 5.18" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 0%, Lag= 0.3 min Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs / 2 Max. Velocity= 9.30 fps, Min. Travel Time= 0.4 min Avg. Velocity = 3.19 fps, Avg. Travel Time= 1.2 min Peak Storage= hrs Average Depth at Peak Storage= 0.64' Bank-Full Depth= 2.50' Flow Area= 4.9 sf, Capacity= cfs 30.0" Round Pipe n= Concrete sewer w/manholes & inlets Length= 237.0' Slope= '/' Inlet Invert= ', Outlet Invert= ' Summary for Pond 1P: StormTech Inflow Area = ac,100.00% Impervious, Inflow Depth > 6.51" for 100-Year event Inflow = hrs, Volume= af Outflow = hrs, Volume= af, Atten= 1%, Lag= 0.5 min Discarded = hrs, Volume= af Primary = hrs, Volume= af

40 P:\104275\ \SupportDocs\Calcs\Drainage\HydroCAD\ Proposed Drainage Conditons_SC740_Rev Rain Type III 24-hr 100-Year Rainfall=6.75" Prepared by Tetra Tech Inc. Printed 6/23/2016 HydroCAD s/n HydroCAD Software Solutions LLC Page 17 Routing by Stor-Ind method, Time Span= hrs, dt= 0.01 hrs Peak Elev= hrs Surf.Area= 1,782 sf Storage= 3,622 cf Plug-Flow detention time= 83.5 min calculated for af (90% of inflow) Center-of-Mass det. time= 34.7 min ( ) Volume Invert Avail.Storage Storage Description #1A ' 1,405 cf 30.00'W x 59.40'L x 3.50'H Field A 6,237 cf Overall - 2,222 cf Embedded = 4,015 cf x 35.0% Voids #2A ' 2,222 cf ADS_StormTech SC-740 x 48 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap Row Length Adjustment= +0.44' x 6.45 sf x 6 rows 3,627 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary ' 24.0" Round Culvert L= 50.0' Ke= Inlet / Outlet Invert= ' / ' S= '/' Cc= n= 0.012, Flow Area= 3.14 sf #2 Device ' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) Coef. (English) #3 Discarded ' in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 0.00' Discarded OutFlow Max= hrs HW=217.49' (Free Discharge) 3=Exfiltration ( Controls 0.04 cfs) Primary OutFlow Max= hrs HW=217.49' (Free Discharge) 1=Culvert (Passes 9.27 cfs of cfs potential flow) 2=Broad-Crested Rectangular Weir (Weir Controls fps) Summary for Link EDB: POA 1 Inflow Area = ac,100.00% Impervious, Inflow Depth > 5.18" for 100-Year event Inflow = hrs, Volume= af Primary = hrs, Volume= af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= hrs, dt= 0.01 hrs

41 Appendix C Groundwater Recharge Calculations

42 20 Corporate Drive Burlington Centre Burlington, MA Calc. By: NHC/MJV Date: 23-Jun-16 Chk. By: Date: Groundwater Recharge Calculations Required Recharge Volume 1 Rv = F x impervious area Where: Rv = required recharge volume (acre-feet) F = target depth factor associated with each hydrologic soil group (inches) Impervious Area = pavement and rooftop area on site (acres) NRCS Hydrologic Soil Type Target Depth Factor (inches) Impervious Area (acre) Approx. Soil Texture Rv (acre-feet) Rv (cf) A sand B loam ,049 C silty loam D clay Total = ,049 Provided Recharge Volume 2 Notes: Infiltration System Static Storage Volume (acre-feet) Static Storage Volume (cf) 1P ,101 Total = ,101 1.) Refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 15 dated February ) Provided recharge volume is based on the Static Method, refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 18 dated February P:\104275\ \SupportDocs\Calcs\Drainage\RECHARGE-CALCS-Overall.xls 7/19/2016

43 20 Corporate Drive Burlington Centre Burlington, MA Calc. By: MJV Date: 23-Jun-16 Chk. By: Date: Groundwater Recharge Calculations Drawdown Calculations Drawdown Time 1 Time drawdown = Rv (K)(Bottom Area) Where: Time drawdown = time it takes the basin to drain completely (hours) Rv = static storage volume (cubic feet) K = saturated hydraulic conductivity 2 (inches/hour) Bottom Area = bottom area of recharge structure (square feet) Infiltration Chamber Rv (cf) K (in/hr) Bottom Area (sf) Drawdown Time (hr) P1 3, , Notes: 1.) Refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 25 dated February ) Refer to Massachusetts Stormwater Handbook Volume 3, Chapter 1, page 22 dated February 2008 (Rawls Rates Table).

44

45 Appendix D Water Quality Calculations

46 20 Corpprate Drive Burlington Centre Burlington, MA MaDEP Standard Method to Convert Required Water Quality Volume to a Discharge Rate Areas (acres) Impervious Tc Water Quality Unit Impervious (A) Pervious Total % Impervious Area (mi 2 ) WQV (inches) CN (min) (hrs) qu (csm/in) Q (cfs) Exist. STC % STC % STC % STC % Water Quality Flow (WQF) = Q = (qu) (A) (WQV) Where: qu = the unit peak discharge (in csm/in) A = impervious surface drainage area ( in square miles) WQV = water quality volume (in inches) Notes: 1. Refer to MaDEP Standard Method to Convert Required Water Quality Volume to a Discharge Rate for Sizing Flow Based Manufactured Proprietary Stormwater Treatment Practices, dated September 10, P:\104275\ \SupportDocs\Calcs\Drainage\Stormceptor\Water Quality Flow Calcs.xlsx 6/29/2016

47 Appendix E StormCAD Report

48 FlexTable: Catchment Table Label CM-1 CM-2 CM-3 CM-4 CM-5 CM-6 CY-1 CY-2 CY-3 R-1 TD-1 Outflow Element CB-1 CB-2 CB-3 CB-4 CB-5 STC-3 CY-1 CY-2 CY-3 RD-1 TD-1 Catchment CA (acres) Rational C Area (User Defined) (acres) Flow (Total Out) (cfs) Time of Concentration (min) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

49 FlexTable: Catch Basin Table Label CB-1 CB-2 CB-3 CB-4 CB-5 CY-1 CY-2 CY-3 MH-10/1P RD-1 STC-3 TD-1 WL-1 Structure Type Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Circular Structure Elevation (Ground) (ft) Elevation (Rim) (ft) Elevation (Invert) (ft) Inlet Drainage Area (acres) (N/A) (N/A) Inlet C (N/A) (N/A) Local Flow Time (min) Flow (Known) (cfs) System CA (acres) Diameter (in) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

50 FlexTable: Manhole Table Label EMH-DP2 EMH-DP4 EMH-E1 EMH-E2 ESTC MH-1 MH-2 MH-3 MH-4 MH-4 MH-5 MH-6 MH-7 MH-11 MH-12 MH-13 MH-14 MH-16 MH-16 MH-28 STC-2 Elevation (Ground) (ft) Elevation (Rim) (ft) Elevation (Invert) (ft) Hydraulic Grade Line (In) (ft) Hydraulic Grade Line (Out) (ft) Diameter (in) Elevation (Invert in 1) (ft) (N/A) (N/A) Elevation (Invert in 2) (ft) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) Elevation (Invert in 3) (ft) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) (N/A) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

51 FlexTable: Conduit Table Velocity (ft/s) Cover (Stop) (ft) Cover (Start) (ft) Hydraulic Grade Line (Out) (ft) Elevation Ground (Stop) (ft) Hydraulic Grade Line (In) (ft) Elevation Ground (Start) (ft) Capacity (Full Flow) (cfs) Flow (cfs) Length (Scaled) (ft) Diameter (in) Slope (Calculate d) (ft/ft) System CA (acres) System Drainage Area (ft²) Upstream Inlet Area (acres) Invert (Stop) (ft) Stop Node Invert (Start) (ft) Start Node Label , MH CB-1 CO ,068.0 (N/A) MH MH-1 CO ,068.0 (N/A) MH MH-2 CO , MH CB-2 CO ,651.2 (N/A) MH MH-3 CO , MH CB-4 CO ,590.4 (N/A) EMH-E MH-4 CO , MH CB-3 CO ,791.6 (N/A) MH MH-6 CO ,791.6 (N/A) EMH-E MH-5 CO , MH RD-1 CO , MH CY-3 CO (N/A) MH MH-10/1P CO (N/A) MH MH-14 CO (N/A) MH MH-13 CO (N/A) MH MH-12 CO , MH STC-3 CO , MH CB-5 CO ,552.8 (N/A) STC MH-7 CO ,920.4 (N/A) MH MH-16 CO , MH CY-2 CO , MH CY-1 CO ,325.6 (N/A) MH MH-28 CO MH TD-1 CO ,033.2 (N/A) O EMH-E1 ECO ,651.2 (N/A) EMH-E ESTC ECO ,651.2 (N/A) ESTC MH-4 ECO ,552.8 (N/A) EMH-DP STC-2 ECO ,552.8 (N/A) EMH-DP EMH-DP2 ECO (N/A) EMH-DP MH-11 ECO ,552.8 (N/A) O EMH-DP4 ECO (N/A) MH WL-1 ECO (N/A) EOGS EMH-E2 ECO (N/A) MH EOGS ECO ,473.2 (N/A) O MH-16 ECO-20 Page 1 of 1 27 Siemon Company Drive Suite 200 W Watertown, CT USA /29/2016 Bentley StormCAD V8i (SELECTseries 3) [ ] Bentley Systems, Inc. Haestad Methods Solution Center _StormCAD_Rev.stsw

52 FlexTable: Outfall Table ID Label MH-9 O-1 O-2 O-3 Elevation (Ground) (ft) Elevation (Invert) (ft) Depth (Node) (ft) Hydraulic Grade (ft) Flow (Total Out) (cfs) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

53 CB-1 Rim: ft Invert: ft Profile Report Engineering Profile - CB-1 to O-1 ( _StormCAD_Rev.stsw) MH-2 Rim: ft Invert: ft MH-1 Rim: ft Invert: ft MH-3 Rim: ft Invert: ft MH-4 Rim: ft Invert: ft ESTC Rim: ft Invert: ft CO-1: ft/ft Circle in CO-2: ft/ft Circle in EMH-E1 Rim: ft Invert: ft O-1 Rim: ft Invert: ft CO-3: ft/ft Circle in CO-5: ft/ft Circle in ECO-3: ft/ft Circle in ECO-1: ft/ft Circle in Station (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

54 Profile Report Engineering Profile - CB-3 to O-1 ( _StormCAD_Rev.stsw) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

55 Profile Report Engineering Profile - CB-4 to O-1 ( _StormCAD_Rev.stsw) Elevation (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

56 Profile Report Engineering Profile - CY-3 to O-1 ( _StormCAD_Rev.stsw) Elevation (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

57 Profile Report Engineering Profile - CB-5 to O-2 ( _StormCAD_Rev.stsw) Elevation (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

58 Profile Report Engineering Profile - MH-10 to O-2 ( _StormCAD_Rev.stsw) MH-10/1P Rim: ft Invert: ft MH-11 Rim: ft Invert: ft EMH-DP4 Rim: ft Invert: ft CO-15: ft/ft Circle in O-2 Rim: ft Invert: ft ECO-6: ft/ft Circle in ECO-7: ft/ft Circle in Concrete Station (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

59 Profile Report Engineering Profile - MH-14 to O-2 ( _StormCAD_Rev.stsw) MH-11 Rim: ft Invert: ft MH-14 Rim: ft Invert: ft MH-13 Rim: ft Invert: ft MH-12 Rim: ft Invert: ft EMH-DP4 Rim: ft Invert: ft ECO-6: ft/ft Circle in O-2 Rim: ft Invert: ft CO-16: ft/ft Circle in PVC CO-17: ft/ft Circle in CO-18: ft/ft Circle in ECO-7: ft/ft Circle in Concrete Station (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

60 Profile Report Engineering Profile - CY-2 to O-2 ( _StormCAD_Rev.stsw) CY-2 Rim: ft Invert: ft EMH-DP4 Rim: ft Invert: ft EMH-DP2 Rim: ft Invert: ft STC-2 Rim: ft Invert: ft MH-7 Rim: ft Invert: ft MH-16 Rim: ft Invert: ft Elevation (ft) CO-33: ft/ft Circle in CO-49: ft/ft Circle in CO-53: ft/ft Circle in O-2 Rim: ft Invert: ft ECO-5: ft/ft Circle in ECO-4: ft/ft Circle in ECO-7: ft/ft Circle in Concrete Station (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

61 Profile Report Engineering Profile - STC-3 to O-3 ( _StormCAD_Rev.stsw) STC-3 Rim: ft Invert: ft MH-16 Rim: ft Invert: ft O-3 Rim: ft Invert: ft CO-21: ft/ft Circle in ECO-20: ft/ft Circle in Station (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

62 Profile Report Engineering Profile - RD-1 to MH-9 ( _StormCAD_Rev.stsw) Elevation (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

63 Profile Report Engineering Profile - TD-1 to O-2 ( _StormCAD_Rev.stsw) Elevation (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

64 Profile Report Engineering Profile - CY-1 to O-3 ( _StormCAD_Rev.stsw) CY-1 Rim: ft Invert: ft Elevation (ft) MH-28 Rim: ft Invert: ft MH-16 Rim: ft Invert: ft O-3 Rim: ft Invert: ft CO-54: ft/ft Circle in CO-55: ft/ft Circle in ECO-20: ft/ft Circle in Station (ft) _StormCAD_Rev.stsw 6/29/2016 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 200 W Watertown, CT USA Bentley StormCAD V8i (SELECTseries 3) [ ] Page 1 of 1

65 Appendix F Operations and Maintenance Plan

66 Operations and Maintenance Plan 20 Corporate Drive Burlington, MA Submitted to: Town of Burlington July 22, 2016

67 Table of Contents 1.0 Introduction and Responsible Party Maintenance Program Inspection and Maintenance Frequency and Corrective Measures Catch Basins Parking Surfaces and Site Access Drives Vegetated Areas Stormceptor Water Quality Structures StormTech Subsurface Infiltration Basin Winter Maintenance Program Fertilizer and Pesticide Use Emergency Spill Containment... 3 List of Figures Figure 1 Plan Showing Structure locations and Pesticide/Fertilizer Restrictions List of Appendices Appendix A Appendix B Appendix C Sample Operation and Maintenance Log and Inspection Forms Stormceptor Owner s Manual StormTech Isolator Row O&M Manual Tetra Tech

68 1.0 Introduction and Responsible Party This long-term Stormwater Management System Operations and Maintenance (O&M) Plan, filed with the Town of Burlington, will be implemented at the Burlington Centre project located at 20 Corporate Drive to ensure that the stormwater management system functions as designed. The Owner, Burlington Centre Twenty Corporate Owner LLC, is the primary responsible party for overseeing and implementing the O&M Plan; although the responsibility may be assigned to a property manager, the Owner is ultimately responsible for implementing this O&M. In case of transfer of property ownership, future property owners shall be notified of the presence of the stormwater management system and their obligation for proper implementation of the O&M Plan. Included in the manual is a Stormwater Management O&M Plan identifying the key components of the stormwater system and a log for tracking inspections and maintainance. The stormwater management system protects and enhances the stormwater runoff water quality through the removal of sediment and pollutants, and source control significantly reduces the amount of pollutants entering the system. Preventive maintenance of the system will include a comprehensive source reduction program of regular vacuuming and litter removal, prohibitions on the use of pesticides, and maintenance of trash areas. The purpose of the Stormwater Operations and Maintenance (O&M) plan is to ensure inspection of the system, removal of accumulated sediments, oils, and debris, and implementation of corrective action and record keeping activities. The ongoing responsibility is the Owner, its successors and assigns. Adequate maintenance is defined in this document as good working condition. Contact information: Responsibility for Operations and Maintenance Name: Address: City, State: Contact: Telephone: TBD TBD TBD TBD TBD 1.1 Documentation An Operation and Maintenance Record Log and Schedule will be kept by the Owner summarizing inspections, maintenance, repairs and any corrective actions taken. The log will include the date on which each inspection or maintenance task was performed, a description of the inspection findings or maintenance completed, and the name of the inspector or maintenance personnel performing the task. Maintenance logs will be kept on file at the Facilities office and copies of Inspection & Maintenance Log sheets indicating all work and inspections will be available to the Town of Burlington upon request. 1.2 Public Safety Features The following measures have been incorporated into the stormwater management system to ensure the safety of the public: Drain manholes and catch basins have been provided with heavy duty covers and/or grates and designed to withstand H20 loading. Treatment of stormwater runoff from paved surfaces has been designed to remove a minimum of 80% TSS. Reduction in peak rates of runoff from the project site under post-development conditions. 1

69 Development and implementation of an Operations and Maintenance Plan to ensure the proper functioning of the stormwater management system. Development and implementation of a Long Term Pollution Prevention Plan identifying potential pollution sources and suitable practices to control them from impacting the environment and/or the public s health and safety. 2.0 Maintenance Program The Owner will ensure that inspections and record keeping are timely and accurate and that cleaning and maintenance are performed at least on a bi-annual basis. Inspection & Maintenance Log Forms shall include the date and the amount of the last significant storm event in excess of 1 of rain in a 24-hour period, physical conditions of the structures, depth of sediment in structures, evidence of overtopping or debris blockage and maintenance required of each structure. 2.1 Inspection and Maintenance Frequency and Corrective Measures The following areas, facilities, and measures will be inspected by the Owner and maintained as specified below. Identified deficiencies will be corrected. Accumulated sediments and debris will be properly handled and disposed of off-site, in accordance with local, state, and federal guidelines and regulations. Figure 1 provides the location of facilities to be inspected. A sample operation and maintenance log and inspection forms are included in Appendix A Catch Basins Catch basins will be inspected quarterly and cleaned when sediment reaches ½ full depth from the invert of the pipe to ensure that the catch basins are working in their intended fashion and that they are free of debris. If the basin outlet is designed with a hood/tee to trap floatable materials, check to ensure watertight seal is working. Sediments and hydrocarbons will be properly handled and disposed of off-site, in accordance with local, state, and federal guidelines and regulations. The method of sediment removal will be by vacuum and disposal must be documented. Any structural damage to the catch basins or to castings must be repaired upon discovery Parking Surfaces and Site Access Drives Accumulations of sand and debris will be cleared from parking lots and site access drives through street sweeping to control the amount of sediment that enters the drainage system. Street sweeping will be conducted quarterly, but primarily in late spring and the early fall seasons. Street sweeping will also occur after winter snowmelt when road sand and other sediments have accumulated Vegetated Areas Inspect slopes and embankments early in the growing season to identify active or potential erosion problems. Replant bare areas or areas with sparse growth. Where rill erosion is evident, armor the area with an appropriate lining or divert the erosive flows to on-site area stabilized or vegetated areas Stormceptor Water Quality Structures There are three (3) proposed Stormceptor water quality units proposed in conjunction with the residential development project. Stormceptor has defined the appropriate inspection and maintenance procedures. Refer to Appendix B of the O&M Plan for the procedure. 2

70 2.1.5 StormTech Subsurface Infiltration Basin The stormwater management system includes one (1) subsurface infiltration basin constructed of StormTech Chambers. StormTech has defined the appropriate inspection and maintenance procedures. Refer to Appendix C of the O&M Plan for the procedure. 2.2 Winter Maintenance Program The landowner will contract with a professional snow removal/winter conditions management contractor to treat the paved parking and walking areas within the project site for safe access during winter conditions. Each storm brings a specific treatment regime based on the temperature regime and precipitation type/amount. Snow will be stored on site or removed from the site in accordance with local, state and federal regulations. The contractor is responsible to minimize de-icing applications while ensuring safe vehicle and pedestrian access throughout the site. In addition to snow removal, potentially icy and unsafe paved surfaces are addressed as follows. The de-icing program will utilize a non-sodium pelletized de-icing material that may contain calcium chloride or magnesium chloride as the active ice melting ingredient. 2.3 Fertilizer and Pesticide Use Since portions of the landscaped outdoor recreation area on the north side of the building could potentially contribute runoff (via overland sheet flow) to the area within 100 feet of the vernal pool, the use of pesticides in this area will be prohibited. In addition, fertilizer must be chemical free. Figure 1 provides a plan showing the area where pesticide use is prohibited and chemical free fertilizer must be used. 3.0 Emergency Spill Containment A spill of greater than 10 gallons of oil or a spill of any quantity that has reached a surface water, into a sewer, storm drain, ditch, or culvert leading to a surface water, shall be immediately reported to one or more municipal, state, or federal authority. In the event of a hazardous waste spill on-site the following protocol should be followed. If it is safe to do so, employees (or on-site property manager) detecting an oil spill should immediately stop the release and use available materials to prevent the spread of oil, particularly to catch basins. If there is a potentially flammable, toxic, or explosive condition, evacuate the vicinity of the spill. If is believed that a reportable or dangerous condition exists, immediately call the local Fire Department to notify them of the release. If it is believed that a reportable condition exists, immediately call the Massachusetts Department of Environmental Protection (DEP) to notify them of the release. Call the DEP Emergency Response Section toll free statewide number, Be prepared to provide the following information to the DEP and the Fire Department: Identity of the caller Contact phone number Location of the spill Type of product spilled 3

71 Approximate quantity or product spilled Extent of actual and/or potential water pollution Date and time of spill Cause of spill Contact a Licensed Site Professional (LSP) to assist in further handling of the material(s) and DEP. 4

72

73 Appendix A Sample Operation and Maintenance Log and Inspection Forms

74 Sample Operation and Maintenance Log Site Maintenance Supervisor: Date: Routine Response to Rainfall Event ( inches) Other BMP Catch Basins Street Sweeping Vegetated Areas Stormceptor Units StormTech Oil/Grit Separators Extended Detention Basins Frequency Quarterly Inspections Semi-Annual Cleaning Quarterly Cleaning Maintenance as necessary Quarterly Inspections Maintenance when 15% storage capacity is reached (min once/year) Immediate Oil/Hazardous Material Removal Semi-Annual Inspections Maintenance as necessary Quarterly Inspections Semi-Annual Cleaning Semi-Annual Inspection Semi-Annual Outlet Structure Integrity Sediment Removal (min. every 5 years) Structures Inspected Date Performed Comments

75 CATCH BASIN INSPECTION FORM 20 CORPORATE DRIVE BURLINGTON, MA OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: CATCH BASIN INSPECTED: CB-1 CB-2 CB-3 CB-4 CB-5 ACCEPTABLE NEEDS WORK NOTES FRAME AND GRATE BRICK/MORTAR P:\104275\ \CAD\SupportFiles\Drainage\O&M Inspection Forms.dwg 6/27/2016 7:44:13 AM OIL HOOD DATE OF CLEANING: DATE OF REPAIR: OUTLET PIPE DEPTH OF SEDIMENT BY WHOM: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS:

76 STORMCEPTOR INSPECTION FORM 20 CORPORATE DRIVE BURLINGTON, MA OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: STORMCEPTOR INSPECTED: STC-1 STC-2 STC-3 ACCEPTABLE NEEDS WORK NOTES FRAME AND COVER OIL PORT P:\104275\ \CAD\SupportFiles\Drainage\O&M Inspection Forms.dwg 6/27/2016 7:44:13 AM INLET WEIR OUTLET DATE OF CLEANING: DATE OF REPAIR: DEPTH OF SEDIMENT BY WHOM: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS:

77 INFILTRATION BASIN INSPECTION FORM 20 CORPORATE DRIVE BURLINGTON, MA OWNER: PROPERTY MANAGER: INSPECTED BY: DATE OF INSPECTION: INFILTRATION BASIN INSPECTED: IFB-1 ACCEPTABLE NEEDS WORK NOTES P:\104275\ \CAD\SupportFiles\Drainage\O&M Inspection Forms.dwg 6/22/ :56:34 AM 4" PVC RISER INSPECTION PORT WITH SCREW-IN CAP DATE OF CLEANING: DATE OF REPAIR: STORMTECH CHAMBER BY WHOM: BY WHOM: NOTE ANY DISCREPANCIES AND SUGGESTED CORRECTIVE ACTIONS:

78 Appendix B Stormceptor Owner s Manual

79 THE STORMCEPTOR SYSTEM Owner s Manual

80 Owner s Manual Page 1 Stormceptor Owner s Manual Contents 1. Stormceptor Overview 2. Stormceptor System Operation 3. Identification of Stormceptor 4. Stormceptor Maintenance Guidelines 4.1 Recommended Maintenance Procedure 4.2 Disposal of Trapped Material from Stormceptor 5. Recommended Safety Procedures 6. Stormceptor Monitoring Protocol 6.1 Pollutants to be Monitored 6.2 Monitoring Methodology Page List of Tables Table 1. Stormceptor Dimensions 4 Table 2. Stormceptor Capacities 5 Table 3. Sediment Depths Indicating Required Maintenance 5 Table 4. Monitoring Pollutants 9 List of Figures Figure 1. Single Inlet/Outlet Disc Insert In-Line Stormceptor 6 Figure 2. STC 450i Inlet Stormceptor 6 Rev. 3/2006 Rinker Materials

81 Owner s Manual Page 2 Thank You! We want to thank you for selecting the Stormceptor System to use in your efforts in protecting the environment. Stormceptor is one of the most effective and maintenance friendly storm water quality treatment devices available. If you have any questions regarding the operation and maintenance of the Stormceptor System, please call your local Rinker Materials representative, or the Stormceptor Information Line at (800) Stormceptor Overview The Stormceptor System is a water quality device used to remove total suspended solids (TSS) and free oil (TPH) from storm water run-off. Stormceptor takes the place of a conventional manhole or inlet structure within a storm drain system. Rinker Materials manufactures the Stormceptor System with precast concrete components and a fiberglass disc insert. A fiberglass Stormceptor can also be provided for special applications. The Stormceptor System product line consists of four patented designs: The In-Line (Conventional) Stormceptor, available in eight model sizes ranging from 900 to 7200 gallon storage capacity. An In-Line (Series) Stormceptor is available in three model sizes ranging from 11,000 to 16,000 gallon storage capacity. The Submerged Stormceptor, an in-line system designed for oil and sediment removal in partially submerged pipes, available in all models sizes ranging from 450i to 16,000 gallon storage capacity. The Inlet Stormceptor is a 450 gallon unit designed for small drainage areas. Stormceptor removes free oil and suspended solids from storm water preventing hazardous spills and non-point source pollution from entering downstream lakes and rivers. Rinker Materials and its affiliates market and manufacture the Stormceptor System in the United States and Australia. Several thousand Stormceptor Systems have been installed in various locations throughout North America, Australia and the Caribbean since In the Stormceptor, a fiberglass insert separates the treatment chamber from the by-pass chamber. The different insert designs are illustrated in Figures 1 and 2. These designs are easily distinguishable from the surface once the cover has been removed. There are four versions of the in-line disc insert: single inlet/outlet, multiple inlet, in-line series insert and submerged designs. In the non-submerged disc design you will be able to see the inlet pipe, the drop pipe opening to the lower chamber, the weir, a 6" oil inspection/cleanout pipe, a large 24" riser pipe opening offset on the outlet side of the structure, and the outlet pipe from the unit. The weir will be around the 24" outlet pipe on the multiple inlet disc insert and on large diameter pipe applications. The STC (series) Stormceptors consist of two chambers comprised of similar fiberglass inserts. These units also contain a 6" oil/inspection cleanout pipe and 24" outlet riser pipes. The submerged disc insert has a higher weir and a second inlet drop pipe. In the inlet design you will be able to see an inlet drop pipe and an outlet riser pipe as well as a central oil inspection/cleanout port. Rinker Materials

82 Owner s Manual Page 3 2. Stormceptor System Operation The Stormceptor consists of a lower treatment chamber, which is always full of water, and a by-pass chamber. Storm water flows into the by-pass chamber via the storm sewer pipe or grated inlet (Inlet Stormceptor). Normal flows are diverted by a weir and drop pipe arrangement into a treatment chamber. Water flows up through the submerged outlet pipe based on the head at the inlet weir and is discharged back into the by-pass chamber downstream of the weir. The treated storm water continues down stream via the storm sewer system. Oil and other liquids with a specific gravity less than water rise in the treatment chamber and become trapped under the fiberglass insert. Sediment will settle to the bottom of the chamber by gravity. The circular design of the treatment chamber is critical to prevent turbulent eddy currents and to promote settling. During infrequent high flow conditions, storm water will by-pass the weir and be conveyed to the outlet sewer directly. The by-pass is an integral part of the Stormceptor since other oil/grit separators have been noted to scour during high flow conditions (Schueler and Shepp, 1993). For further details please refer to The Stormceptor System Technical Manual. The key benefits of Stormceptor include: Capable of removing more than 80% of the total sediment load when properly applied as a source control for small drainage areas Removes free oil from storm water during normal flow conditions Will not scour or resuspend trapped pollutants Ideal spill control device for commercial and industrial developments Vertical orientation facilitates maintenance and inspections Small foot print 3. Identification of Stormceptor All In-Line (including Submerged) Stormceptors are provided with their own frame and cover. The cover has the name STORMCEPTOR clearly embossed on it to allow easy identification of the unit. The name Stormceptor is not embossed on the inlet models due to the variability of inlet grates used/approved across North America. You will be able to identify the Inlet Stormceptor by looking into the grate since the insert will be visible. Once you have located a unit, there still may be a question as to the size of the unit. Comparing the measured depth from the water level (bottom of insert) to the bottom of the tank with Table 1 should help determine the size of the unit. Rinker Materials

83 Owner s Manual Page 4 Starting in 1996, a metal serial number tag has been affixed to the fiberglass insert. If the unit does not have a serial number, or if there is any uncertainty regarding the size of the Stormceptor using depth measurements, please contact the Rinker Materials Stormceptor information line at (800) for assistance. 4. Stormceptor Maintenance Guidelines Table 1. Stormceptor Dimensions* Model Pipe Invert to Top of Base Slab 450i 60" " " " " " " " " 11000s 128"** 13000s 150"** 16000s 134"** * Depths are approximate ** Depths per structure The performance of all storm water quality measures that rely on sedimentation decreases as they fill with sediment (See Table 2 for Stormceptor capacities). An estimate of performance loss can be made from the relationship between performance and storage volume. Rinker Materials recommends maintenance be performed when the sediment volume in the unit reaches 15% of the total storage. This recommendation is based on several factors: Sediment removal is easier when removed on a regular basis (as sediment builds up it compacts and solidifies making maintenance more difficult). Development of a routine maintenance interval helps ensure a regular maintenance schedule is followed. Although the frequency of maintenance will depend on site conditions, it is estimated that annual maintenance will be required for most applications; annual maintenance is a routine occurrence which is easy to plan for and remember. A minimal performance degradation due to sediment build-up can occur. In the event of any hazardous material spill, Rinker Materials recommends maintenance be performed immediately. Maintenance should be performed by a licensed liquid waste hauler. You should also notify the appropriate regulatory agencies as required. Rinker Materials

84 Owner s Manual Page 5 Table 2. Stormceptor Capacities Model Sediment Capacity ft 3 (L) Oil Capacity US gal (L) Total Holding Capacity US gal (L) 450i 45 (1276) 86 (326) 470 (1779) (2135) 251 (950) 952 (3604) (3202) 251 (950) 1234 (4671) (5470) 251 (950) 1833 (6939) (4387) 840 (3180) 2462 (9320) (9134) 840 (3180) 3715 (14063) (13158) 909 (3441) 5059 (19150) (17235) 909 (3441) 6136 (23227) (20551) 1059 (4009) 7420 (28088) 11000s 942 (26687) 2797 (10588)* (42374) 13000s 1230 (34841) 2797 (10588)* (50528) 16000s 1470 (41632) 3055 (11564)* (60256) * Total both structures combined 4.1 Recommended Maintenance Procedure For the disc design, oil is removed through the 6" inspection/cleanout pipe and sediment is removed through the 24" diameter outlet riser pipe. Alternatively, oil could be removed from the 24" opening if water is removed from the treatment chamber, lowering the oil level below the drop pipes. The depth of sediment can be measured from the surface of the Stormceptor with a dipstick tube equipped with a ball valve (Sludge Judge ). It is recommended that maintenance be performed once the sediment depth exceeds the guideline values provided in Table 3 for the reasons noted in Section 4.0 Stormceptor Maintenance Guidelines. Table 3. Sediment Depths Indicating Required Maintenance Model Sediment Depth* 450i 8" (200 mm) 900 8" (200 mm) " (250 mm) " (375 mm) " (300 mm) " (425 mm) " (375 mm) " (450 mm) " (375 mm) 11000s 17" (425 mm)** 13000s 20" (500 mm)** 16000s 17" (425 mm)** * Depths are approximate ** In each structure Rinker Materials

85 Owner s Manual Page 6 No entry into the unit is required for routine maintenance of the Inlet Stormceptor or the smaller disc insert models of the In-Line Stormceptor. Entry to the level of the disc insert may be required for servicing the larger disc insert models. Any potential obstructions at the inlet can be observed from the surface. The fiberglass insert has been designed as a platform for authorized maintenance personnel in the event that an obstruction needs to be removed. Typically, maintenance is performed by the Vacuum Service Industry, a well established sector of the service industry that cleans underground tanks, sewers, and catch-basins. Costs to clean a Stormceptor will vary based on the size of the unit and transportation distances. If you need assistance for cleaning a Stormceptor unit, contact your local Rinker Materials representative, or the Stormceptor Information Line at (800) Figures 1 and 2 will help illustrate the access point for routine maintenance of Stormceptor. Sediment and oil removal can be performed by vacuums Oil removal can be performed by vacuum truck through the oil/inspection port Disc Insert Concrete Stormceptor Figure 1 Single Inlet/Outlet Disc Insert In-Line Stormceptor Inlet Grate Oil Port Inlet Insert Removable Tee Maintenance Figure 2 STC 450i Inlet Stormceptor Rinker Materials

86 Owner s Manual Page Disposal of Trapped Material from Stormceptor The requirements for the disposal of material from Stormceptor are similar to that of any other Best Management Practices (BMP). Local guidelines should be consulted prior to disposal of the separator contents. In most areas the sediment, once dewatered, can be disposed of in a sanitary landfill. It is not anticipated that the sediment would be classified as hazardous waste. In some areas, mixing the water with the sediment will create a slurry that can be discharged into a trunk sanitary sewer. In all disposal options, approval from the disposal facility operator/agency is required. Petroleum waste products collected in Stormceptor (oil/chemical/fuel spills) should be removed by a licensed waste management company. What if I see an oil rainbow or sheen at the Stormceptor outlet? With a steady influx of water with high concentrations of oil, a sheen may be noticeable at the Stormceptor outlet. This may occur because a rainbow or sheen can be seen at very small oil concentrations (< 10 ppm). Stormceptor will remove over 95% of all free oil and the appearance of a sheen at the outlet with high influent oil concentrations does not mean that the unit is not working to this level of removal. In addition, if the influent oil is emulsified, the Stormceptor will not be able to remove it. The Stormceptor is designed for free oil removal and not emulsified or dissolved oil conditions. 5.0 Recommended Safety Procedures Rinker Materials strongly recommends that any person who enters a Stormceptor System follow all applicable OSHA regulations for entry in permit required confined spaces, as outlined in 29 CFR A permit required confined space consists of a space that: Is large enough and so configured that an employee can bodily enter and perform assigned work. Has limited or restricted means for entry and exit. Is not designed for continuous employee occupancy. Contains or has one of the following: - a potential to contain a hazardous atmosphere. - a material that has the potential for engulfing an entrant. - any other recognized serious safety hazard. Storm water and wastewater systems fall under OSHA guidelines for a permit required confined space. Failure to follow OSHA guidelines for entry and work in a permit required confined space can result in serious injury or death. Please exercise extreme caution and follow appropriate safety procedures when entering any confined space. Two square pick holes in the cover vent the Stormceptor, allow for removal of the cover, and provide sampling ports for air quality monitoring before the cover is removed. If you must enter the Stormceptor, please note that if the disc insert inside is wet, it can be slippery. Rinker Materials

87 Owner s Manual Page 8 Recognizing that every work site is different, the responsibility for safety falls on the contractor. The contractor must ensure that all employees and subcontractors follow established safety procedures and OSHA regulations for working in and around permit required confined spaces as well as for any other safety hazard that may be present on that particular site. 6.0 Stormceptor Monitoring Protocol If monitoring of your Stormceptor System is required, we recommend you follow the procedures outlined below by the Rinker Materials Stormceptor office. If you have any questions regarding monitoring please contact the Rinker Materials Stormceptor Product Manager at (800) Pollutants to be Monitored Table 4 indicates the pollutants to be monitored during the storm events and the minimum acceptable detection limit for each pollutant to be analyzed. Approved federal or state laboratory analysis methodologies are to be used for the analysis. The optional metals indicated in Table 4 refer to the Resource Conservation Recovery Act and may be covered by a generic metals scan. Bacteria monitoring will not be required unless explicitly requested elsewhere. Two sediment samples are to be extracted from the monitored Stormceptor at the end of the study and analyzed for the particle size distribution and water content. A minimum of 8 U.S. sieve sizes should be used to determine the particle size distribution. Sieves that are used must include, but are not limited to 35, 60, 100, 140, 200, 270 and 400. Three clay particle sizes must be analyzed to denote particle sizes between 5 and 25 µm. The particle size distributions should be plotted on a standard grain size distribution graph. Rinker Materials

88 Owner s Manual Page Monitoring Methodology Table 4. Monitoring Pollutants Pollutant Minimum Detection Limit (MDL) Total Suspended Solids (TSS) 5 mg/l Total Phosphorus (P) 0.02 mg/l Total Kjeldahl Nitrogen (TKN) 0.1 mg/l Copper (Cu) mg/l Cadmium (Cd) mg/l Lead (Pb) 0.05 mg/l Zinc (Zn) 0.01 mg/l Chromium (Cr) 0.01 mg/l Total Petroleum Hydrocarbons (TPH) 1 mg/l Conductivity 0.1 µmho/cm Fecal Coliform* 1/100 ml Additional Metals (optional) Arsenic (As) Barium (Ba) Mercury (Hg) Selenium (Se) Silver (Ag) mg/l 0.01 mg/l mg/l mg/l 0.01 mg/l * Only if explicitly requested in Terms of Reference The following monitoring protocol should be followed to ensure reasonable monitoring results and interpretation: Monitoring protocols should conform to EPA 40 CFR Part 136. The EPA guideline of 72 hours dry period prior to a monitoring event should be used. This will ensure that there is sufficient pollutant build-up available for wash-off during the monitored event. Flow proportional monitoring must be conducted for the parameters indicated in Table 1. Samples should be analyzed separately for the first flush versus the remainder of the storm event. Monitoring need not extend longer than an 8-hour period after the start of the storm event (composite). Sediment sampling (measuring the sediment depth in the unit at the beginning and end of the monitoring period) must be conducted. The water content of the sediment layer must be analyzed to determine the dry volume of suspended solids. Sediment depth sampling will indicate the rate of pollution accumulation in the unit, provide confirmation that the unit is not scouring and confirm the flow proportional monitoring results. A mass balance using the sediment sampling should be calculated to validate the flow proportional sampling. Rinker Materials

89 Owner s Manual Page 10 Grab sampling (just taking samples at the inlet and outlet) is an unacceptable methodology for testing the performance of the Stormceptor during wet weather conditions unless it is flow weighted (flow weighted composite sample from numerous grab samples) over the entire storm. The oil containment area underneath the insert should be inspected via the vent pipe for dry weather spills capture once a month during the monitoring period since the flow rate of a dry weather spill may not trigger the automated samplers. A tipping bucket rain gauge should be installed on-site to record the distribution of storm intensities and rainfall volume during the monitored events. Results that are within the laboratory error (both inlet and outlet) or are representative of relatively clean water should be discarded. Typical concentrations of pollutants in storm water are: TSS Total P TKN Total Cu Total Pb Total Zn 100 mg/l 0.33 mg/l 1.50 mg/l 34 µg/l 144 µg/l 160 µg/l A threshold first flush/composite TSS value of 50 mg/l at the inlet to the Stormceptor should be used as the lower limit of an acceptable storm for reporting event efficiency. Monitoring results where the influent TSS concentration is less than 50 mg/l should only be used in mass load removal calculations over the entire monitoring period with other storms where the influent concentration is greater than 50 mg/l. The results should not be analyzed if the influent TSS concentrations during all monitored storms are less than 50 mg/l. Storms where the influent TSS concentration is less than 10 mg/l should be discarded from all analyses. A threshold storm event volume equal to 1.5 times the storage volume of the Stormceptor being monitored should be used as the lower limit of an acceptable storm for monitoring. Sampling at the outlet of the Stormceptor should be conducted within the 24" outlet riser pipe to accurately define event performance. The personnel monitoring the Stormceptor should record incidental information in a log file. Information such as weather, site conditions, inspection and maintenance information, monitoring equipment failure, etc. provide valuable information that can explain anomalous results. Laboratory results of monitored samples should be analyzed within 10 days of being submitted to the lab. Weekly inspections of the sampling tubes, flow meter, rain gauge, and quality samplers should be conducted to ensure proper operation of the monitoring equipment. Debris and sediment that collects around the sampling intakes should be cleaned after each event. During the installation of automated quality samplers, care should be exercised to ensure that representative samples will be extracted (placement of intakes, ensuring that tubing is not constricted or crimped). Sampling should be conducted for a minimum of 6 storms. Ideally 15 storms should be sampled if the budget allows. Rinker Materials

90 Call the Stormceptor Information Line ( ) for more detailed information and test results. TECHNICAL INFORMATION: Stormceptor CD ROM Stormceptor Technical Manual Stormceptor Installation Guide Stormceptor Brochure TEST RESULTS: STEP Report (Independent Verification) University of Coventry Study ETV Canada (Federal Verification) National Water Research Institute Test Westwood, MA Field Monitoring Study Edmonton, Canada Field Monitoring Study Seattle Field Monitoring Como Park, MN Field Monitoring Study Florida Atlantic University Submerged Stormceptor Testing Oil Removal Field Validation Sludge Analyses and Particle Size Analyses 6560 Langfield Rd., Bldg. 3 Houston, TX Phone: Fax: Toll Free: Rinker Materials Corp. Rev. 3/2006

91 Appendix C StormTech Isolator Row O&M Manual

92 Detention Retention Water Quality Save Valuable Land and Protect Water Resources A division of Isolator Row O&M Manual StormTech Chamber System for Stormwater Management

93 1.0 The Isolator Row 1.1 INTRODUCTION An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row is a patented technique to inexpensively enhance Total Suspended Solids (TSS) removal and provide easy access for inspection and maintenance. The Isolator Row is typically designed to capture the first flush and offers the versatility to be sized on a volume basis or flow rate basis. An upstream manhole not only provides access to the Isolator Row but typically includes a high flow weir such that storm water flowrates or volumes that exceed the capacity of the Isolator Row overtop the over flow weir and discharge through a manifold to the other chambers. The Isolator Row may also be part of a treatment train. By treating storm water prior to entry into the chamber system, the service life can be extended and pollutants such as hydrocarbons can be captured. Pre-treatment best management practices can be as simple as deep sump catch basins, oil-water separators or can be innovative storm water treatment devices. The design of the treatment train and selection of pretreatment devices by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, the Isolator Row is recommended by StormTech as an effective means to minimize maintenance requirements and maintenance costs. Looking down the Isolator Row from the manhole opening, woven geotextile is shown between the chamber and stone base. 1.2 THE ISOLATOR ROW The Isolator Row is a row of StormTech chambers, either SC-310, SC-310-3, SC-740, DC-780, MC-3500 or MC models, that is surrounded with filter fabric and connected to a closely located manhole for easy access. The fabric-wrapped chambers pro vide for settling and filtration of sediment as storm water rises in the Isolator Row and ultimately passes through the filter fabric. The open bottom chambers and perforated sidewalls (SC-310, SC and SC-740 models) allow storm water to flow both vertically and horizon tally out of the chambers. Sediments are cap tured in the Isolator Row protecting the storage areas of the adjacent stone and chambers from sediment accumulation. Note: See the StormTech Design Manual for detailed information on designing inlets for a StormTech system, including the Isolator Row. StormTech Isolator Row with Overflow Spillway (not to scale) MANHOLE WITH OVERFLOW WEIR OPTIONAL PRE-TREATMENT STORMTECH ISOLATOR ROW Two different fabrics are used for the Isolator Row. A woven geotextile fabric is placed between the stone and the Isolator Row chambers. The tough geo textile provides a media for storm water filtration and provides a durable surface for maintenance operations. It is also designed to prevent scour of the underlying stone and remain intact during high pressure jetting. A non-woven fabric is placed over the chambers to provide a filter media for flows passing through the perforations in the sidewall of the chamber. The non-woven fabric is not required over the DC-780, MC-3500 or MC-4500 models as these chambers do not have perforated side walls. ECCENTRIC HEADER OPTIONAL ACCESS STORMTECH CHAMBERS 2 Call StormTech at or visit our website at for technical and product information.

94 2.0 Isolator Row Inspection/Maintenance 2.1 INSPECTION The frequency of Inspection and Maintenance varies by location. A routine inspection schedule needs to be established for each individual location based upon site specific variables. The type of land use (i.e. industrial, commercial, residential), anticipated pollutant load, percent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspections. Initially, the Isolator Row should be inspected every 6 months for the first year of operation. For sub sequent years, the inspection should be adjusted based upon previous observation of sediment deposition. The Isolator Row incorporates a combination of standard manhole(s) and strategically located inspection ports (as needed). The inspection ports allow for easy access to the system from the surface, eliminating the need to perform a confined space entry for inspection purposes. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to determine the depth of sediment. When the average depth of sediment exceeds 3 inches throughout the length of the Isolator Row, clean-out should be performed. 2.2 MAINTENANCE The Isolator Row was designed to reduce the cost of periodic maintenance. By isolating sediments to just one row, costs are dramatically reduced by eliminating the need to clean out each row of the entire storage bed. If inspection indicates the potential need for maintenance, access is provided via a manhole(s) located on the end(s) of the row for cleanout. If entry into the manhole is required, please follow local and OSHA rules for a confined space entries. Examples of culvert cleaning nozzles appropriate for Isolator Row maintenance. (These are not StormTech products.) Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water nozzle to propel itself down the Isolator Row while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the manhole for vacuuming. Most sewer and pipe maintenance companies have vacuum/jetvac combination vehicles. Selection of an appropriate JetVac nozzle will improve maintenance efficiency. Fixed nozzles designed for culverts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45 are best. Most JetVac reels have 400 feet of hose allowing maintenance of an Isolator Row up to 50 chambers long. The JetVac process shall only be performed on StormTech Isolator Rows that have AASHTO class 1 woven geotextile (as specified by StormTech) over their angular base stone. StormTech Isolator Row (not to scale) NOTE: NON-WOVEN FABRIC IS ONLY REQUIRED OVER THE INLET PIPE CONNECTION INTO THE END CAP FOR DC-780, MC-3500 AND MC-4500 CHAMBER MODELS AND IS NOT REQUIRED OVER THE ENTIRE ISOLATOR ROW. Call StormTech at or visit our website at for technical and product information. 3

95 3.0 Isolator Row Step By Step Maintenance Procedures Step 1) Inspect Isolator Row for sediment A) Inspection ports (if present) i. Remove lid from floor box frame ii. Remove cap from inspection riser iii. Using a flashlight and stadia rod, measure depth of sediment and record results on maintenance log. iv. If sediment is at, or above, 3 inch depth proceed to Step 2. If not proceed to step 3. B) All Isolator Rows i. Remove cover from manhole at upstream end of Isolator Row ii. StormTech Isolator Row (not to scale) 1) B) 1) A) 2 Using a flashlight, inspect down Isolator Row through outlet pipe 1. Mirrors on poles or cameras may be used to avoid a confined space entry 2. Follow OSHA regulations for confined space entry if entering manhole iii. If sediment is at or above the lower row of sidewall holes (approximately 3 inches) proceed to Step 2. If not proceed to Step 3. Step 2) Clean out Isolator Row using the JetVac process A) A fixed culvert cleaning nozzle with rear facing nozzle spread of 45 inches or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required Step 3) Replace all caps, lids and covers, record observations and actions Step 4) Inspect & clean catch basins and manholes upstream of the StormTech system 4 Sample Maintenance Log Stadia Rod Readings Fixed point Fixed point Date to chamber to top of bottom (1) sediment (2) Sediment Depth Observations/Actions Inspector (1) - (2) 3/15/ ft. none New installation. Fixed point is Cl frame at grade djm 9/24/ ft. Some grit felt sm 6/20/ ft. Mucky feel, debris visible in manhole and in rv Isolator row, maintenance due 7/7/ ft. 0 System jetted and vacuumed djm Detention Retention Water Quality A division of 70 Inwood Road, Suite 3 Rocky Hill Connecticut fax ADS Terms and Conditions of Sale are available on the ADS website, Advanced Drainage Systems, the ADS logo, and the green stripe are registered trademarks of Advanced Drainage Systems. Stormtech and the Isolator Row are registered trademarks of StormTech, Inc. Green Building Council Member logo is a registered trademark of the U.S. Green Building Council Advanced Drainage Systems, Inc. SO /13

96 Appendix G Supporting Documentation

97 20 Corporate Drive Burlington Centre Burlington, MA For Catchments CB 1, CB 2, CB 3 & CB 4 TSS Removal Efficiency Calculations BMP C D E F TSS Removal Rate Starting TSS Load* Amount Removed (C*D) Remaining Load (D-E) TSS Removal Calculation Worksheet Street Sweeping - 5% Deep Sump and Hooded Catch Basin Proprietary Treatment Practice Total TSS Removal = 82% * Equals remaining load from previous BMP (E) which enters the BMP P:\104275\ \SupportDocs\Calcs\Drainage\TSS Removal Calcs.xls 6/29/2016

98 20 Corporate Drive Burlington Centre Burlington, MA For Catchments CB 5 and CB 6 TSS Removal Efficiency Calculations BMP C D E F TSS Removal Rate Starting TSS Load* Amount Removed (C*D) Remaining Load (D-E) TSS Removal Calculation Worksheet Street Sweeping - 5% Deep Sump and Hooded Catch Basin Proprietary Treatment Practice Oil Grit Separator Extended Dry Detention Basin Total TSS Removal = 87% *Equals remaining load from previous BMP (E) which enters the BMP P:\104275\ \SupportDocs\Calcs\Drainage\TSS Removal Calcs.xls 6/29/2016

99 FOUNDATION ENGINEERING REPORT BURLINGTON RESIDENTIAL DEVELOPMENT BURLINGTON, MASSACHUSETTS JUNE 27, 2016 Prepared For: TDC Development Group, LLC 125 High Street, 21st Floor Boston, MA Massachusetts Avenue Cambridge, MA (617) PROJECT NO. 6030

100 June 27, 2016 TDC Development Group, LLC 125 High Street, 21st Floor Boston, MA Attention: Reference: Mr. Chris Chandor Burlington Residential Development; Burlington, Massachusetts Foundation Engineering Report Ladies and Gentlemen: This report documents the results of our recent subsurface exploration and foundation design study for the proposed Burlington Residential Development to be located at Corporate Drive in Burlington, Massachusetts. Refer to the Project Location Plan, Figure 1 for the general site location. This report was prepared in accordance with our proposal dated January 14, 2016 and the authorization of TDC Development Group, LLC (TDC). These services are subject to the limitations contained in Appendix A. Purpose and Scope The purposes of the subsurface exploration program and foundation design study are to provide an assessment of the subsurface soil and groundwater conditions across the building footprint as they relate to foundation design of the structure. Previous subsurface explorations from our files performed within the limits of the proposed development were also utilized as part of this study. Foundation design includes foundation support of the proposed building and its lowest level slab, treatment of the lowest level slab in consideration of groundwater, and seismic design considerations in accordance with the provisions of the Eighth Edition of the Massachusetts State Building Code (Code). Foundation construction considerations relating to geotechnical aspects of the proposed structure are also presented herein. Available Information Information provided to McPhail Associates, LLC (McPhail) by TDC included following: A 30-scale drawing entitled Conceptual Grading Plan dated September 28, 2015 and prepared by Tetra Tech; A 30-scale drawing entitled Grading and Drainage Plan dated November 23, 2015 and prepared by Tetra Tech. GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERS 2269 Massachusetts Avenue Cambridge, Massachusetts (617)

101 TDC Development Group, LLC June 27, 2016 Page 2 A set of architectural drawings entitled The Residences at Burlington Centre dated November 23, 2015 and prepared by Cube 3 Studio. Elevations referenced are understood to be referenced to the National Geodetic Vertical Datum (N.G.V.D.). Existing and Proposed Conditions The site fronts onto Corporate Drive to the east, and is bounded by the commercial properties to the east and south, and wooded area to the north. The project site currently consists of a bituminous concrete parking lots and grassed areas. Existing ground surface generally slopes downward from northeast to the southwest portion of the site from about Elevation +240 to Elevation A wetland area is indicated to be located on the northern portion of the subject site. Based on the information provided to us, the proposed development will include the construction of a five-level wood residential structure on top of a two level reinforced concrete garage. The building will consist of an approximate 79,218 square-foot footprint which is anticipated to occupy the majority of the parcel. It is understood that the proposed building will not contain any below grade space, but will be benched into the existing and proposed slopes located within the eastern, western and southwestern portions of the proposed building. The lowest-level slab is proposed to be constructed at Elevation Also, it is understood that a stormwater infiltration system and retaining walls will be constructed as part of the site development. Since the lowest level slab is proposed to be constructed at about Elevation , cuts of about 4.5 to 8 feet will be required within the eastern side of the proposed building footprint, and excavation as deep as 23.5 feet below the existing ground surface will be required across the northeastern edge of the proposed building footprint. Across the western portion of the site, the proposed building will generally require placement of fill up to 2 feet to establish the proposed grades. Existing Subsurface Information Based on information from our files, it is understood that sixteen (16) test pits were performed as part of previous subsurface explorations in the vicinity of the project site in June 2001 and November Based on our review of the subsurface exploration data, the test pits were advanced to depths ranging from about 2.5 to 16 feet below the existing ground surface and were terminated within either natural lacustrine, alluvial or glacial outwash deposits or bedrock. Test pit logs prepared by McPhail are contained in Appendix B following the text of this report. The approximate exploration locations are indicated on the attached Figure 2.

102 TDC Development Group, LLC June 27, 2016 Page 3 Recent Subsurface Explorations A subsurface exploration program consisting of ten (10) borings was conducted at the site, on May 16 and May 17, 2016 by Geosearch, Inc. (Geosearch) of Fitchburg, Massachusetts under contract to McPhail. Locations of the borings are as indicated on the attached Subsurface Exploration Plan, Figure 2. Logs of the borings prepared by McPhail are contained in Appendix C. The borings were drilled utilizing a truck-mounted drill rig using hollow-stem augers and NW casing. Standard 1-3/8-inch I.D. split-spoon samples and standard penetration tests were generally obtained at maximum 5-foot intervals of depth in accordance with the standard procedures described in ASTM D1586. The borings were advanced to depths ranging from about 2 to 16.8 feet below the existing ground surface and were terminated within either natural alluvial deposits or possible bedrock. To permit monitoring of groundwater level at the site, a groundwater observation well was installed within completed borehole B-7 located within the proposed stormwater infiltration system. A Groundwater Monitoring Report of the observation well is contained in Appendix D. The borings were monitored by a McPhail field representative who performed field layout, prepared field logs, obtained and visually classified soil samples, monitored groundwater conditions in the completed borings and observation well, made minor relocations, and determined the required exploration depths based upon the actual subsurface conditions encountered. Field locations of the borings were determined by taping from existing site features included on the above-referenced plan prepared by Tetra Tech. The existing ground surface elevation at each boring location was determined by a level survey performed by our field staff utilizing vertical control information on the above-referenced plan prepared by Tetra Tech. Laboratory Testing At the completion of the recent field work, soil samples were returned to our laboratory for more detailed classification, analysis and testing. The laboratory testing consisted of sieve analyses to determine the gradations and confirm the visual classifications of the fill, alluvial and lacustrine deposits. Laboratory test procedures were in general accordance with applicable ASTM Standards. Results of the gradation testing for the fill, alluvial and lacustrine deposits appear on Figures 6, 7 and 8, respectively.

103 TDC Development Group, LLC June 27, 2016 Page 4 Subsurface Conditions Detailed descriptions of the subsurface conditions encountered within each of the explorations are presented on the test pit and boring logs contained in Appendices B and C, respectively. Following is a discussion of the generalized subsurface conditions across the site which are inferred from the prior and recent explorations, and also from our knowledge of local site geology, and is presented discussed above. Topsoil and forest mat deposits were encountered directly below ground surface in 11 of the 16 previously performed test pits. The topsoil ranged from 0.5 to 1 feet in thickness. The topsoil consisted of a loose, dark brown, silty sand with organic matter. Forest mat consisted of loose, dark brown, silty sand with some organic matter and heavy rooting. The recent borings performed within the existing parking lot encountered 3 to 6 inches thickness of bituminous asphalt. Each of the exploration encountered a fill deposit. The fill was observed to vary from a loose to dense brown silt and sand with some gravel varying to sand and gravel, trace to some silt with varying amounts of blast rock, boulders, cobbles, concrete, metal, brick, cinder and ashes. The fill deposit was observed to vary from about 2 to 13.5 feet in thickness. Results of gradation analyses performed on representative samples of the fill deposit are presented on Figure 6. A subsoil deposit was encountered below the fill and topsoil within the previously performed test pits, and varied from about 0.5 to 2 feet in thickness. The subsoil was generally observed to consist of a compact, orange to yellow-brown silty sand with trace to some gravel and occasional cobbles and roots. Underlying topsoil and subsoil deposits, test pits TP-1, TP-3, and TP-5 performed within the northeast portion of the site encountered glacial till deposit. The glacial till deposit was observed to consist of a dense to very dense gravelly silty sand varying to silty sand and gravel. The glacial till deposit was observed at depths of 1 to 2 feet below ground surface corresponding to Elevation +226 and Elevation Beneath the fill deposit, an organic silt deposit varying from a 1.5 to 5.5-foot in thickness was encountered within the explorations performed at the western portion of the site. The organic silt deposit was observed to consist of a very soft, black organic silt with some peat and roots. Beneath the fill and/or organic deposits, each of the exploration performed within the western portion of the building footprint and borings B-7 and B-8 performed within southeastern side of the site encountered natural alluvial and/or lacustrine deposits. The alluvial deposit consisted of a compact, gray brown, fine to medium silty sand and gravel varying to silt and sand. Results of gradation analyses performed on representative samples of the alluvial deposit are presented on Figure 7. The lacustrine deposit consisted of compact brown, silt with some fine sand varying to silt and sand. Results of gradation

104 TDC Development Group, LLC June 27, 2016 Page 5 analyses performed on representative sample of the lacustrine deposit are contained on Figure 8. The surface of the natural alluvial and/or lacustrine deposit encountered within the explorations performed within the building footprint was observed to vary between depths of 8.5 to 13.5 below ground surface corresponding to Elevation +204 and Elevation A natural glacial outwash deposit was encountered within two test pits performed at the northwest and southwest side of the project site. The glacial outwash generally consisted of gray to brown, gravelly sand varying to sand and gravel, trace silt with occasional cobbles and boulders. A contour plan indicating the elevation of the top of natural soil deposits (glacial till, extremely fractured bedrock, glacial outwash, alluvial, and lacustrine deposits) across the site is presented on the enclosed Figure 3. Within the eastern side of the proposed building footprint, the explorations encountered bedrock at depths ranging from 1.5 to 9.1 feet below ground surface corresponding to Elevation to Elevation The surface of the bedrock within this area is extremely fractured and could be excavated in the test pit explorations to depths varying from about 2.5 to 6.5 feet before encountering refusal on sound bedrock. A contour plan indicating the elevation of the top of sound bedrock across the site is presented on the enclosed Figure 4. Groundwater was generally encountered in the completed explorations performed within the western portion of the proposed building footprint ranging between depths of 6.5 and 12.5 feet below the existing ground surface corresponding to Elevation and Elevation However, groundwater was not encountered in explorations located within the eastern side at the site upon completion. In addition, groundwater was not encountered in the observation well installed in B-7 (OW). Furthermore, it is anticipated that groundwater levels may vary due to factors such as normal seasonal changes, runoff particularly during or following periods of heavy precipitation, and alterations of existing drainage patterns. Infiltration Rate Based on a laboratory grain-size analysis performed on a fill sample obtained from boring B-7 (OW) at a depth of 4 to 6 feet below ground surface, the soil is categorized as a Sandy Loam by utilizing United States Department of Agriculture (USDA) classification system. Therefore, based on Table Rawls Rate from the Massachusetts Stormwater Handbook, the fill deposit in boring B-7 (OW) is estimated to have an infiltration rate of 1.02 inches/hour.

105 TDC Development Group, LLC June 27, 2016 Page 6 Foundation Design Recommendations Based on the results of the subsurface exploration program, the bedrock surface across the eastern the portion of the proposed building footprint was encountered to vary from about 4.5 to 21.5 feet above the proposed lowest level slab. In addition, within the southeastern side of the proposed building, the natural alluvial deposit was encountered to be about 7.5 feet below the proposed lowest level slab. Furthermore, within the western side of the proposed building footprint underlying the fill and organic silt deposits, the presence of the natural alluvial and/or lacustrine deposit was observed to extend to a depth of 10 feet below the existing ground surface. Therefore, based on the scope of the proposed development and subsurface conditions encountered at the site, the most economical foundation support option based on the existing soil conditions is considered to be a conventional spread footing foundation system in conjunction with slab-on-grade construction for the lowest level slab. It is recommended that spread footing located within the eastern portion of the proposed building footprint bear directly on the natural undisturbed glacial till, alluvial, lacustrine deposit or bedrock or on compacted structural fill placed directly over the surface of the glacial till, alluvial, lacustrine deposits or bedrock following removal of the overlying existing topsoil, forest mat, subsoil and fill materials. However, the proposed spread footing foundations and conventional slab-on-grade within the western portion of the building footprint are recommended to be improved by Aggregate Pier (AP) installed through the existing fill and organic deposits. The proposed locations of the continuous spread footings bearing directly on the alluvial, glacial till or lacustrine deposits, bedrock, structural fill or on the ground improvement within the footprint of the proposed building are shown on the enclosed plan entitled Foundation Design Recommendations, Figure 5. It is recommended that the footings be proportioned utilizing a maximum allowable design bearing pressure of two (2) tons per square-foot (tsf). Recommended minimum footing widths for continuous and isolated spread footings are 24 and 30 inches, respectively. All perimeter foundations and interior foundations located adjacent to unheated areas should be provided with a minimum 4-foot thickness of soil cover as frost protection. Interior footings below heated areas should be located such that the top of the foundation concrete is at least 6 inches below the underside of the lowest level slab. Additionally, all foundations should be located such that they are below a theoretical line drawn upward and outward at 2 to 1 (horizontal to vertical) from the bottom exterior edge of all adjacent footings, structures and utilities. Where the existing fill is present below the design bottom of footing, the existing fill should be overexcavated to the undisturbed alluvial, glacial till or lacustrine deposit or to the surface of bedrock, whichever is shallower, and replaced with compacted structural fill. The lateral limits of overexcavation at the surface of the bearing stratum should extend a horizontal distance beyond the edge of the foundation equal to the distance between the

106 TDC Development Group, LLC June 27, 2016 Page 7 bottom of the footing and the exposed natural bearing stratum plus two feet in all plan directions. All fill placed within the building footprint should consist of structural fill. Where the structural fill is placed in areas that will be improved with ground improvement, the fill may be compacted to 92 percent of its maximum modified Proctor density. Elsewhere, the structural fill should be compacted to at least 95 of its maximum modified Proctor density. Structural fill should be placed in lifts having a maximum compacted thickness of 6 inches. Structural fill should consist of a well-graded sand and gravel from a naturally-occurring source and contain a maximum of 8 percent by weight passing the number 200 sieve. Reuse of the on-site fill and/or crushed and proposed bedrock as structural fill will require special measures to maximize their reuse as discussed in more detail in the Foundation Construction Considerations section of this report. Aggregate Piers - Ground Improvement Installation In general, the AP cavity is created by driving a specially designed 12 to 30-inch diameter mandrel and tamper foot/vibrator using a large static force augmented by dynamic vertical impact energy. A sacrificial cap or other method is used to prevent soil from entering the mandrel during driving. This method of advancement eliminates spoils as all penetrated soils are displaced laterally. After driving to the design depth, which would extend into the alluvial, glacial till or lacustrine deposits or to the top of the bedrock surface, the aggregate is placed inside the mandrel and the mandrel is raised leaving a lift of aggregate in the cavity. The tamper foot/vibrator is repeatedly raised and then driven and vibrated back down forming an approximate one-foot thick, compacted lift. This process is repeated to the top of the cavity, forming the AP. The compaction densifies the aggregate and increases the lateral stress in the soil matrix beneath the proposed building. Thus, the potential for large settlements is reduced by improving the unsuitable soils to a stiffer composite soil matrix. Since ground improvement techniques such as APs are provided by a design-build consultant, detailed design calculations should be submitted to the Architect for review prior to the beginning of construction. A detailed explanation of the design parameters for capacity and settlement calculations should be included in the design submittal. The design submittal should also include a testing program to demonstrate the capacity of the AP elements. All calculations and drawings should be prepared and sealed by a Professional Engineer licensed in the Commonwealth of Massachusetts, and retained by the Contractor who is to perform the work. APs shall be designed such that the reinforced soil matrix is capable of supporting a minimum allowable bearing pressure of 2 tons per square-foot. The maximum design bearing pressure should be verified by the AP contractor using a modulus test. Additionally, the AP-improved soils shall limit long-term total settlement of footings to less than 1-inch and limit long-term differential settlement of adjacent footings to less than 1/2-inch.

107 TDC Development Group, LLC June 27, 2016 Page 8 Lowest Level Slab The lowest level slab in the lobby areas, trash rooms, mechanical rooms, locker rooms and similar areas of the proposed building are recommended to be designed as a conventional slab-on-grade which is directly underlain by a polyethylene vapor barrier spread over the slab subgrade. The slab subgrade should consist of a minimum 9-inch thickness of compacted granular fill. The existing fill exposed at the slab subgrade should be proof compacted with a minimum of six passes of a 10-ton vibratory drum roller prior to the placement of structural fill. After the proof compaction, all soft and/or weaving subgrade areas should be removed and replaced with compacted granular fill. Structural fill should consist of a well-graded sand and gravel from a naturally-occurring source and have a maximum of 8 percent by weight passing the number 200 sieve. Where the proposed lowest level floor slab is to be located above the proposed exterior finished grades, perimeter drainage is not considered necessary. Additionally, since the first floor will be utilized for the parking garage installation of the underslab drainage is not considered to be necessary. Furthermore, the exterior finished grade should be pitched away from the perimeter walls to minimize surface water infiltration. All localized depressions in the lowest level slab (such as elevator pits) should be provided with properly tied continuous waterstops in all construction joints and cementitious waterproofing to protect against groundwater intrusion. Foundation and Retaining Walls As indicated above, the proposed building will be benched into the into the existing and proposed slopes located at the eastern, western, and southwestern side of the site. Therefore, in consideration of the potential for groundwater to be periodically or seasonally perched on the surface of the bedrock surface, it is recommended that where the exterior grade is located 18 inches or grater above the lowest level floor slab, the proposed foundation wall of the proposed building should be provided with perimeter drainage to protect the occupied below-grade space against groundwater intrusion. The drainage should consist of a foundation drain pipe embedded within a minimum 6-inch thickness of ¾-inch crushed stone which is surrounded by filter fabric and backfilled with a free draining gravel to within 18 inches of final grade. Alternatively, a prefabricated drainage product such as Miradrain 6000 should be installed directly along the exterior of the wall that that should be tide directly into the crushed stone envelope surrounding the foundation drain. The upper 18 inches of backfill should be relatively impervious ordinary fill with the finished grade pitched away from the wall to minimize surface water infiltration. Furthermore, it is recommended that drainage be provided along the site retaining walls. General Foundation Recommendations Below-grade foundation walls receiving lateral support at the top and bottom (i.e., restrained walls) should be designed for a lateral earth pressure corresponding to an

108 TDC Development Group, LLC June 27, 2016 Page 9 equivalent fluid density of 60 pounds per cubic foot. Cantilevered or unrestrained retaining walls may be designed utilizing a lateral earth pressure corresponding to an equivalent fluid density of 40 pounds per cubic foot subject to the walls being provided with positive drainage to prevent hydrostatic pressures from acting on the walls. To these values must be added the pressures attributable to earthquake forces per Section of the Code. Lateral forces can be considered to be transmitted from the structure to the soil by passive pressure against the foundation walls utilizing an equivalent fluid density of 120 pounds per cubic-foot providing that the walls are designed to resist these pressures. Lateral force can also be considered to be transmitted from the structure to the soil by friction on the base of footings using a coefficient of 0.40, to which a safety factor of 1.5 should be applied. Seismic Design Considerations For the purposes of determining parameters for structural seismic design, this site is considered to be a Site Class D as defined in Section of the Code. Furthermore, the bearing strata on the proposed site is not considered to be subject to liquefaction during an earthquake based on the criterion of Section of the Code. Foundation Construction Considerations The primary foundation construction considerations include removal of obstructions at AP foundation locations, preparation of foundation bearing surfaces and slab-on-grade, on-site reuse of excess excavated soil and rock, implementation of controlled blasting procedures for removal of bedrock, construction dewatering and off-site disposal of excess excavated material. Removal of obstructions to aggregate pier installation should be performed on an as-needed basis. Excavations to remove obstructions should be backfilled with ordinary fill after all oversized material has been removed. The fill should be replaced in maximum 2-foot lifts and tamped with the backhoe bucket to facilitate future aggregate pier installation. The below-grade obstructions should be removed in their entirety wherever they interfere with the new construction, however, they may remain in-place under the proposed building provided that they are in excess of 18 inches below the lowest level slab and do not interfere with the foundation or utility installation. Preparation of the building pad within the eastern side of the proposed building footprint for support of the spread footings should include the removal of all existing site improvements, utilities topsoil, forest mat, and subsoil from within the building footprint. To minimize disturbance of the AP-improved soil and the alluvial, glacial till, or lacustrine deposit bearing surfaces, it is recommended that the final excavation to expose the surface of the bearing stratum at footing locations be performed utilizing an excavator that has a smooth-edged toothless bucket. Further, it is recommended that bearing surfaces be

109 TDC Development Group, LLC June 27, 2016 Page 10 immediately covered with a 3-inch thickness of 3/4-inch crushed stone to minimize disturbance of the subgrade during subsequent forming operations. Spread footings which bear on bedrock should be provided with a minimum 6-inch thick cushion of 3/4-inch crushed stone placed directly on the bedrock surface. Bedrock bearing surfaces should be leveled to a maximum slope of 1 vertical to 12 horizontal prior to placing the minimum 6-inch thickness of compacted 3/4-inch crushed stone. All displaced or uplifted rock fragments should be removed from the proposed bearing surfaces prior to placement of the crushed stone. For preparation of the slab-on-grade subgrade soils, the exposed fill subgrade should be proof compacted with a minimum of six passes of a 10-ton vibratory drum roller prior to the placement of structural fill. All soft or compressible areas detected by the proofrolling should be excavated and be replaced with compacted structural fill. It is anticipated that the excavated fill and alluvial material may be re-used on-site as structural fill. In addition, on-site soil mixed with rock, boulders and cobbles which are culled out and crushed to a maximum particle size of 4 inches may be reused on-site as structural fill below buildings or within 2 feet below finished grade in paved or landscaped areas, provided it is protected from wet and freezing environments and can be compacted to the recommended densities. It is recommended that the placement and compaction of the on-site materials be completed during relatively dry and non-freezing conditions. Stockpiled excavated material designated for reuse on-site should be covered at all times with 6-mil polyethylene for protection from precipitation and also as a dust mitigation measure. If, due to any of the above conditions, the excavated material becomes unsuitable for reuse, it should be removed from the site and an off-site gravel fill should be used. Based on the results of the subsurface explorations and the proposed grading and lowest level slab elevations, some bedrock excavation is anticipated to be required at the northeast building corner. Conventional excavation methods should be used to the fullest extent possible prior to resorting to the use of hoe rams and/or drilling and blasting. If blasting is required, the contract documents should limit the resultant peak particle velocity at the limit of work lines to a maximum of 2.0 inch per second. The resultant peak particle velocity should be monitored during all blasting operations. The blasting contractor should prepare and submit a blasting plan for review by the design team prior to commencement of rock excavation. In addition, a written and visually recorded preconstruction survey of all adjacent structures within 250 feet of the proposed blasting site should be completed and submitted prior to commencement of blasting operations. It is anticipated that dewatering, if required, by means of strategically located sumps and trenches should suffice during foundation construction operations. In addition, trapped surface water may accumulate within localized depressions in the ground surface across the site after periods of heavy precipitation and will most likely necessitate localized sumping. It is recommended that all pumped groundwater be discharged on-site. If pumped

110 TDC Development Group, LLC June 27, 2016 Page 11 groundwater cannot be discharged on-site, it would be necessary to dispose of pumped groundwater into a nearby storm drain or combined sewer which may require the need for a temporary groundwater discharge permit. Should excess excavated soil generated from the proposed construction require off-site disposal, current Department of Environmental Protection (DEP) policies and regulations for off-site reuse of excess excavated soil require environmental characterization of the excavated soil prior to its off-site reuse. Final Comments McPhail has been retained to provide design final foundation design recommendations and design assistance services during the final design phase of this project. The purpose of this involvement is to prepare the earthwork specification section and review the structural drawings as a check on implementation of our recommendations into the Contract Documents for construction of the proposed building. It is recommended that McPhail be retained during the earthwork and foundation construction period to observe the installation of the aggregate pier and conventional foundation elements. In the event of any construction difficulties or differing conditions, our familiarity with the subsurface conditions and foundation design would aid in arriving at an expeditious and economical solution. We trust that the above is sufficient for your present requirements. Should you have any questions concerning the recommendations presented herein, please do not hesitate to call us. Very truly yours, McPHAIL ASSOCIATES, LLC Fatima Babic-Konjic, P.E. Chris M. Erikson, P.E. F:\WP5\REPORTS\6030 FER docx FBK/cme

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112 TP-21 TP-22 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o TP-13 B-1 B-3 B-2 B-4 TP-10 APPROXIMATE LIMITS OF PROPOSED BUILDING LOWEST LEVEL SLAB EL ' VERNAL POOL BUFFER FORMER LIMITS OF 88 CAMBRIDGE STREET BUILDING B-5 TP-8 TP-6 TP-5 B-6 TP-3 TP-1 BUFFER B-10 TP-7 TP-14 TP-2 TP-4 B-8 FIGURE NORTH 2 B-7 (OW) TP-12 TP-11 TP-9 B-9 FILE NAME: H:\Acad\JOBS\6030\6030-F02.dwg LEGEND APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LANDSCAPE CREATIONS ON NOVEMBER 1 & 2, 2007 FOR McPHAIL ASSOCIATES, LLC APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LINCOLN TREE AND LANDSCAPE ON JUNE 1, 2001 FOR McPHAIL ASSOCIATES, LLC APPROXIMATE LOCATION OF BOREHOLE PERFORMED BY GEOSEARCH, INC. ON MAY 16 AND 17, 2016 FOR McPHAIL ASSOCIATES, LLC. (OW) APPROXIMATE LOCATION OF PROPOSED STORMWATER INFILTRATION SYSTEM INDICATES OBSERVATION WELL INSTALLED WITHIN COMPLETED BOREHOLE. REFERENCE: THIS PLAN WAS PREPARED FROM A 30-SCALE DRAWING ENTITLED "CONCEPTUAL GRADING PLAN" DATED SEPTEMBER 28, 2015 BY TETRA TECH BURLINGTON GRAPHIC SCALE BURLINGTON RESIDENTIAL DEVELOPMENT SUBSURFACE EXPLORATION PLAN FOR TDC DEVELOPMENT GROUP, LLC BY McPHAIL ASSOCIATES, LLC MASSACHUSETTS MAY 2016 F.G.P. F.B.K. 1" = 50' 6030

113 o FILE NAME: H:\Acad\JOBS\6030\6030-F03_Contour.dwg NORTH TP-21 (+212.7) TP-22 (+199.5) o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o TP-13 (+206.5) TP-12 (+205.0) LEGEND B-1 (+204.1) B-3 (+203.9) B-2 (+202.8) B-4 (+204.0) APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LANDSCAPE CREATIONS ON NOVEMBER 1 & 2, 2007 FOR McPHAIL ASSOCIATES, LLC TP-11 APPROXIMATE LIMITS OF PROPOSED BUILDING LOWEST LEVEL SLAB EL (+213.0) TP-10 APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LINCOLN TREE AND LANDSCAPE ON JUNE 1, 2001 FOR McPHAIL ASSOCIATES, LLC (+206.5) APPROXIMATE LOCATION OF BOREHOLE PERFORMED BY GEOSEARCH, INC. ON MAY 16 AND 17, 2016 FOR McPHAIL ASSOCIATES, LLC. 100' VERNAL POOL BUFFER FORMER LIMITS OF 88 CAMBRIDGE STREET BUILDING B-5 (NE) TP-9 (+220.0) (OW) (+258.0) (NE) TP-6 (+215.5) TP-8 (+218.0) TP-5 (+218.0) B-6 (NE) TP-3 APPROXIMATE LOCATION OF PROPOSED STORMWATER INFILTRATION SYSTEM (+226.0) INDICATES OBSERVATION WELL INSTALLED WITHIN COMPLETED BOREHOLE. TP-1 CONTOUR ELEVATION OF TOP OF NATURAL SOIL (REFER TO NOTES 1 THROUGH 3) ELEVATION OF TOP OF NATURAL SOIL ENCOUNTERED AT EXPLORATION LOCATION INDICATES TOP OF NATURAL SOIL NOT ENCOUNTERED AT EXPLORATION LOCATION BUFFER (+224.0) TP-14 B-10 (NE) B-7 (OW) (+207.9) B-9 (NE) TP-7 (NE) (+218.0) TP-2 (NE) TP-4 (+214.0) B-8 (+206.9) BURLINGTON NOTES: GRAPHIC SCALE FOR FIGURE BURLINGTON RESIDENTIAL DEVELOPMENT TOP OF NATURAL SOIL CONTOUR PLAN TDC DEVELOPMENT GROUP, LLC BY McPHAIL ASSOCIATES, LLC MASSACHUSETTS MAY 2016 F.G.P. F.B.K. 1" = 50' CONTOURS PRESENTED ARE BASED ON LINEAR INTERPOLATION BETWEEN EXPLORATIONS. THE ACTUAL FIELD CONDITIONS MAY VARY FROM THE INDICATED CONTOURS. 2. LINEAR INTERPOLATION TO PRODUCE CONTOURS DOES NOT ACCOUNT FOR EXPLORATION LOCATIONS WHERE NATURAL SOIL WAS NOT ENCOUNTERED. 3. NATURAL SOIL FOR THE PURPOSE OF THIS FIGURE INCLUDE: GLACIAL TILL, GLACIAL OUTWASH, ALLUVIAL, AND LACUSTRINE DEPOSIT AND EXTREMELY FRACTURE BEDROCK. REFERENCE: THIS PLAN WAS PREPARED FROM A 30-SCALE DRAWING ENTITLED "CONCEPTUAL GRADING PLAN" DATED SEPTEMBER 28, 2015 BY TETRA TECH

114 o FILE NAME: H:\Acad\JOBS\6030\6030-F04_Contour.dwg NORTH TP-21 (+210.4) TP-22 (NE) o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o TP-13 (NE) TP-12 (NE) LEGEND B-1 (NE) B-3 (NE) B-2 (NE) B-4 (NE) APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LANDSCAPE CREATIONS ON NOVEMBER 1 & 2, 2007 FOR McPHAIL ASSOCIATES, LLC TP-11 TP-10 (NE) (+207.5) APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LINCOLN TREE AND LANDSCAPE ON JUNE 1, 2001 FOR McPHAIL ASSOCIATES, LLC APPROXIMATE LOCATION OF BOREHOLE PERFORMED BY GEOSEARCH, INC. ON MAY 16 AND 17, 2016 FOR McPHAIL ASSOCIATES, LLC. APPROXIMATE LIMITS OF PROPOSED BUILDING LOWEST LEVEL SLAB EL ' VERNAL POOL BUFFER B-5 (+203.2) FORMER LIMITS OF 88 CAMBRIDGE STREET BUILDING TP-9 (+216.0) (OW) (+258.0) (NE) TP-8 (+213.5) TP-6 (+213.0) TP-5 (+213.5) B-6 (+217.4) TP-3 APPROXIMATE LOCATION OF PROPOSED STORMWATER INFILTRATION SYSTEM (+223.0) INDICATES OBSERVATION WELL INSTALLED WITHIN COMPLETED BOREHOLE. CONTOUR ELEVATION OF TOP OF BEDROCK (REFER TO NOTES 1 THROUGH 3) ELEVATION OF TOP OF BEDROCK ENCOUNTERED AT EXPLORATION LOCATION INDICATES TOP OF BEDROCK NOT ENCOUNTERED AT EXPLORATION LOCATION TP-1 BUFFER (+222.0) TP-14 (+211.5) B-10 (+217.8) B-7 (OW) (NE) B-9 (NE) TP-7 (+236.5) TP-2 (+238.5) TP-4 (+212.0) B-8 (NE) BURLINGTON NOTES: GRAPHIC SCALE FOR FIGURE BURLINGTON RESIDENTIAL DEVELOPMENT TOP OF BEDROCK CONTOUR PLAN TDC DEVELOPMENT GROUP, LLC BY McPHAIL ASSOCIATES, LLC MASSACHUSETTS MAY 2016 F.G.P. F.B.K. 1" = 50' CONTOURS PRESENTED ARE BASED ON LINEAR INTERPOLATION BETWEEN EXPLORATIONS. THE ACTUAL FIELD CONDITIONS MAY VARY FROM THE INDICATED CONTOURS. 2. LINEAR INTERPOLATION TO PRODUCE CONTOURS DOES NOT ACCOUNT FOR EXPLORATION LOCATIONS WHERE BEDROCK WAS NOT ENCOUNTERED. 3. ELEVATION OF TOP OF BEDROCK REPRESENTS THE TOP OF MODERATELY FRACTURED TO SOUND BEDROCK AS INTERPRETED BY REFUSAL AT EXPLORATION LOCATIONS. REFERENCE: THIS PLAN WAS PREPARED FROM A 30-SCALE DRAWING ENTITLED "CONCEPTUAL GRADING PLAN" DATED SEPTEMBER 28, 2015 BY TETRA TECH

115 TP-21 TP-22 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o TP-13 B-1 B-3 B-2 TP-10 APPROXIMATE LIMITS OF PROPOSED BUILDING LOWEST LEVEL SLAB EL ' VERNAL POOL BUFFER GROUND IMPROVEMENT FOR FOOTINGS AND SLAB (LIGHT SHADED) FORMER LIMITS OF 88 CAMBRIDGE STREET BUILDING B-4 B-5 TP-8 TP-6 TP-5 B-6 TP-3 TP-1 BUFFER CONVENTIONAL FOOTINGS (DARK SHADED) B-10 TP-7 TP-14 TP-2 TP-4 B-8 FIGURE NORTH 5 B-7 (OW) TP-12 TP-11 TP-9 B-9 FILE NAME: H:\Acad\JOBS\6030\6030-F05.dwg LEGEND APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LANDSCAPE CREATIONS ON NOVEMBER 1 & 2, 2007 FOR McPHAIL ASSOCIATES, LLC APPROXIMATE LOCATION OF TEST PIT PERFORMED BY LINCOLN TREE AND LANDSCAPE ON JUNE 1, 2001 FOR McPHAIL ASSOCIATES, LLC APPROXIMATE LOCATION OF BOREHOLE PERFORMED BY GEOSEARCH, INC. ON MAY 16 AND 17, 2016 FOR McPHAIL ASSOCIATES, LLC. (OW) APPROXIMATE LOCATION OF PROPOSED STORMWATER INFILTRATION SYSTEM INDICATES OBSERVATION WELL INSTALLED WITHIN COMPLETED BOREHOLE. REFERENCE: THIS PLAN WAS PREPARED FROM A 30-SCALE DRAWING ENTITLED "CONCEPTUAL GRADING PLAN" DATED SEPTEMBER 28, 2015 BY TETRA TECH BURLINGTON GRAPHIC SCALE BURLINGTON RESIDENTIAL DEVELOPMENT FOR BY McPHAIL ASSOCIATES, LLC MASSACHUSETTS FOUNDATION DESIGN RECOMMENDATIONS TDC DEVELOPMENT GROUP, LLC MAY 2016 F.G.P. F.B.K. 1" = 50' 6030

116 FILE NAME: H:\Acad\JOBS\6030\6030-F06_Sieve.dwg 6030 McPHAIL ASSOCIATES, LLC B-6 S-1 0.5'-1.8' B-7 (OW) S-3 4'-6' B-8 S-2 5'-7' FILL 6 FIGURE

117 FIGURE McPHAIL ASSOCIATES, LLC FILE NAME: H:\Acad\JOBS\6030\6030-F07_Sieve.dwg B-4 S-3 10'-12' B-8 S-4 15'-15.5' ALLUVIAL DEPOSIT

118 FIGURE McPHAIL ASSOCIATES, LLC FILE NAME: H:\Acad\JOBS\6030\6030-F08_Sieve.dwg B-1 S-3 10'-12' LACUSTRINE DEPOSIT

119 APPENDIX A: LIMITATIONS

120 LIMITATIONS This report has been prepared on behalf of and for the exclusive use of TDC Development Group, LLC for specific application to the proposed Burlington Residential Development to be located at Corporate Drive in Burlington, Massachusetts in accordance with generally accepted soil and geotechnical engineering practices. No other warranty, expressed or implied, is made. In the event that any changes in nature or design of the proposed construction are planned, the conclusions and recommendations contained in this report should not be considered valid unless the changes are reviewed and conclusions of this report modified or verified in writing by McPhail Associates. The analyses and recommendations presented in this report are based upon the data obtained from the subsurface explorations performed at the approximate locations indicated on the enclosed plan. If variations in the nature and extent of subsurface conditions between the widely spaced explorations become evident during the course of construction, it will be necessary for a re-evaluation of the recommendations of this report to be made after performing on-site observations during the construction period and noting the characteristics of any variations.

121 APPENDIX B: TEST PIT LOGS TP-1 THROUGH TP-14, TP-21 AND TP-22 PREPARED BY MCPHAIL

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138 APPENDIX C: BORING LOGS B-1 THROUGH B-10 PREPARED BY MCPHAIL

139 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center At the west side of the project site. Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-1 Groundwater Observations Date Depth 9.5 Elev Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT S1 24/ S1 (0.5'-2.5'): Loose, brown, SAND and SILT, some gravel. (FILL) FILL S2 24/ S2 (5'-7'): Dense, brown, SAND and GRAVEL. (FILL) ORGANIC DEPOSIT LACUSTRINE DEPOSIT S3 24/ S3 (10'-12'): Compact, brown, SILT, some fine sand. (LACUSTRINE DEPOSIT) ALLUVIAL DEPOSIT Bottom of borehole at 16.8 feet below ground surface. S4 22/ /4" S4 (15'-16.8'): Compact, gray-brown, fine to medium SILTY SAND, some gravel with iron oxidation. Gravel in nose of spoon. (ALLUVIAL DEPOSIT) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Weather: Mostly Cloudy MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

140 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center At the west side of the project site. Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-2 Groundwater Observations Date Depth 9.5 Elev Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT FILL ORGANIC DEPOSIT ALLUVIAL DEPOSIT Bottom of borehole at 14 feet below ground surface. S1 S2 S3 S4 24/14 24/12 24/10 24/ WOH WOH WOH S1 (0.5'-2.5') : Very dense, GRAVEL and SAND, some silt. (FILL) S2 (5'-7'): Very soft, black ORGANIC SILT, some peat, trace wood. (ORGANIC DEPOSIT) S3 (10'-12'): Compact, gray, fine to medium SILTY SAND, trace gravel. (ALLUVIAL DEPOSIT) S4 (12'-14'): Compact, gray to brown, silty medium SAND, some gravel. (ALLUVIAL DEPOSIT) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Weather: Mostly Cloudy MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

141 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center At the west side of the project site. Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-3 Groundwater Observations Date Depth 9.5 Elev Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT S1 24/ S1 (0.5'-2.5'): Dense, brown, SAND and GRAVEL, some silt, trace ash and cinders. (FILL) FILL S2 24/ S2 (5'-7'): Very loose, brown, GRAVEL and SAND. (FILL) ALLUVIAL DEPOSIT Bottom of borehole at 14 feet below ground surface. S3 S4 24/15 24/ S3 (10'-12'): Compact, gray, fine SILTY SAND. (ALLUVIAL DEPOSIT) S4 (12'-14'): Dense, gray, fine to medium, SILTY SAND, some gravel. (ALLUVIAL DEPOSIT) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Weather: Overcast MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

142 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center At the west side of the project site. Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-4 Groundwater Observations Date Depth 10.5 Elev Notes Depth (ft) BLOWS/FT >50 BLOWS/FT. < >30 Elev. (ft) Symbol GRANULAR SOILS DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD Depth to Strata Change (ft) Notes: Stratum Description ASPHALT FILL ALLUVIAL DEPOSIT Bottom of borehole at 13.8 feet below ground surface. Auger refusal at 13.8 feet. Possible bedrock. SOIL COMPONENT Weather: Partly Sunny PID (ppm) DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% No. S1 S2 S3 Sample Pen. /Rec. (in) 24/10 24/12 24/14 Depth (ft) Blows Per 6" MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" Sample Description and Boring Notes S1 (0.5'-2.5'): Compact, brown, SAND and GRAVEL, some silt, trace ash and cinders. (FILL) S2 (5'-7'): Dense, brown, GRAVEL and SILTY fine SAND. (FILL) S3 (10'-12') : Very dense, brown, WELL GRADED MIXTURE OF SILT, SAND and GRAVEL. (ALLUVIAL DEPOSIT) Groundwater McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1 Well Log

143 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center At the west side of the project site. Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-5 Groundwater Observations Date Depth Elev. Notes Depth (ft) BLOWS/FT >50 BLOWS/FT. < >30 Elev. (ft) Symbol GRANULAR SOILS DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD Depth to Strata Change (ft) 9.1 Notes: Stratum Description FILL Bottom of borehole at 9.3 feet below ground surface.auger refusal at 9.2 feet. Possible bedrock. SOIL COMPONENT Groundwater not encountered. Weather: Partly Sunny PID (ppm) DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% No. S1 S2 Sample Pen. /Rec. (in) 24/16 24/15 Depth (ft) Blows Per 6" MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" Sample Description and Boring Notes S1 (0'-2'): Dense, brown, SAND and GRAVEL, some silt. (FILL) S2 (5'-7'): Very dense, brown to gray, fractured rock, some sand. (FILL) Groundwater McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1 Well Log

144 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center Parking Lot Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-6 Groundwater Observations Date Depth Elev. Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT FILL Bottom of borehole at 2 feet below ground surface. Auger and split spoon refusal on possible bedrock or blast fill. S1 16/ /4" S1 (0.5'-1.8'): Very dense, brown, GRAVEL, some sand, trace silt. (FILL) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Groundwater not encountered. Weather: Mostly Sunny MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

145 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center Parking Lot Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-7(OW) Groundwater Observations Date Depth Elev. Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT FILL ALLUVIAL DEPOSIT Bottom of borehole at 16 feet below ground surface. S1 S2 S3 S4 S5 S6 18/15 24/18 24/14 24/4 24/12 24/ S1 (0.5'-2.5'): Very dense, brown, SAND and GRAVEL. (FILL) S2 (2'-4'): Very dense, brown, SAND and GRAVEL, some silt with wood. (FILL) S3 (4'-6'): Very dense, brown, gray, GRAVEL, some sand, trace silt.(fill) S4 (6'-8'): Dense, gray, GRAVEL. (FILL) S5 (10'-12'): Compact, SILTY medium SAND and GRAVEL. (FILL) S6 (14'-16'): Very dense, brown, fine to medium SAND and GRAVEL, some silt. (ALLUVIAL DEPOSIT) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Observation well installed in completed boring. No groundwater observed within the installed well. Weather: Sunny MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

146 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center Parking Lot Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-8 Groundwater Observations Date Depth Elev. Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT FILL ALLUVIAL DEPOSIT Bottom of borehole at 15.5 feet below ground surface. S1 S2 S3 S4 18/6 24/8 24/12 6/ S1 (0.5'-2.0'): Very dense, brown, SAND and GRAVEL, trace brick. (FILL) S2 (5'-7'): Compact, brown, SANDY GRAVEL, some silt. (FILL) S3 (10'-12'): Compact, brown, fine SAND, some gravel, some silt, trace wood. (FILL) S4 (15'-15.5'): Compact, gray, WELL GRADED MIXTURE OF SILT, SAND and GRAVEL. (ALLUVIAL DEPOSIT) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Groundwater not encountered. Weather: Sunny MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

147 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center Parking Lot Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-9 Groundwater Observations Date Depth Elev. Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log ASPHALT FILL Bottom of borehole at 12 feet below ground surface. S1 S2 S3 24/13 24/12 24/ S1 (0.5'-2'): Very dense, brown, gray, SAND and GRAVEL, trave brick, ash and cinders. (FILL) S2 (5'-7'): Dense, brown, SAND and GRAVEL, some silt. (FILL) S3 (10'12'): Compact, brown, SILTY SAND and GRAVEL. (FILL) GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Notes: Groundwater not encountered. Weather: Sunny MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1

148 Project: Location: City/State: Contractor: Driller/Helper: Logged By: Geosearch, Inc. Chris/Jay Michael Sachs Surface Elevation (ft): Burlington Center At the west side of the project site. Burlington, Massachusetts Casing Type/Size: Job #: Date Started: Date Finished: NA Casing Hammer WT(#)/Drop(in): Sampler Type/Size: 24"/Split Spoon Sampler Hammer WT(#)/Drop(in): lb/30" Boring No. B-10 Groundwater Observations Date Depth No GW Elev. 0.0 Notes Depth (ft) Elev. (ft) Symbol Depth to Strata Change (ft) Stratum Description PID (ppm) No. Sample Pen. /Rec. (in) Depth (ft) Blows Per 6" Sample Description and Boring Notes Groundwater Well Log GRANULAR SOILS BLOWS/FT >50 BLOWS/FT. < >30 DENSITY V.LOOSE LOOSE COMPACT DENSE V.DENSE COHESIVE SOILS DENSITY V.SOFT SOFT FIRM STIFF V.STIFF HARD 2.0 Notes: FILL Bottom of borehole at 2 feet below ground surface. Auger and split spoon refusal on possible bedrock or blast fill. SOIL COMPONENT DESCRIPTIVE TERM PROPORTION OF TOTAL "TRACE" 0-10% "SOME" 10-20% "ADJECTIVE" 20-35% (eg SANDY, SILTY) "AND" 35-50% Weather: Sunny MATERIALS CONTAINING THREE SOIL COMPONENTS EACH OF WHICH COMPRISES AT LEAST 25% OF THE TOTAL ARE CLASSIFIED AS "A WELL GRADED MIXTURE OF" McPHAIL ASSOCIATES, LLC 2269 MASSACHUSETTS AVENUE CAMBRIDGE, MA TEL: FAX: Page 1 of 1