COMMONWEALTH OF MASSACHUSETTS EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS DEPARTMENT OF ENVIRONMENTAL PROTECTION

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1 COMMONWEALTH OF MASSACHUSETTS EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS DEPARTMENT OF ENVIRONMENTAL PROTECTION SOUTHEAST REGIONAL OFFICE 20 RIVERSIDE DRIVE, LAKEVILLE, MA DEVAL L. PATRICK Governor TIMOTHY P. MURRAY Lieutenant Governor IAN A. BOWLES Secretary LAURIE BURT Commissioner Mr. John Delano Town of Halifax Board of Health 499 Plymouth Street, 2 nd Floor Halifax, MA June 25, 2008 RE: AT: APROVAL WITH CONDITIONS BWP SW 43 LANDFILL CLOSURE COMPLETION FINAL COVER SYSTEM Hemlock Lane Landfill Halifax, MA Transmittal Number: W Dear Mr. Delano: The Massachusetts Department of Environmental Protection, ( MassDEP"), has completed its technical review of the Application for Determination of Completion and Post Closure Planning ( Application ) for the Town of Halifax, Hemlock Lane Landfill ( Landfill ), and has found that it is technically complete. Accordingly, the Application is approved subject to the conditions herein. The Application was reviewed according to the Solid Waste Management Regulations at 310 CMR and the Landfill Technical Assistance Guidance Manual, revised May 1997 (the "Manual"). Application Summary The Application was prepared by Brown & Caldwell, Middleboro, Massachusetts ( B&C ) on behalf of the Town of Halifax (the Town ) and submitted to MassDEP on November 30, The Application consists of a transmittal form assigned number W134376, a BWP SW 43 Landfill Closure Completion application form, an Application Narrative, a Construction Quality Assurance Report, a geomembrane panel layout drawing prepared by New England Liner Systems, Inc. and an As-Built drawing prepared by Lynnfield Engineering, Inc., professional land surveyors, all bound within a single document entitled: This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at TDD# or DEP on the World Wide Web: Printed on Recycled Paper

2 BWP SW 43 Landfill Closure Completion Hemlock Lane landfill Halifax Massachusetts November 2007 B&C submitted supplemental application information on March 13, 2008, April 21, 2008 and June 3, 2008 in response to comments ed to B&C on December 26, Landfill Status Operation of the Hemlock Lane Landfill by the Town began in the 1930 s and continued through The Landfill was utilized as a burn dump for Town generated Municipal Solid Waste ( MSW ) until Between 1971 and 1977, MSW was disposed in large trenches on the eastern portion of the site and placed in a shallow layer approximately one to two feet below the ground surface on the western part of the site. The Landfill s 5.2 acre footprint is comprised of the two (2) acre portion of the land adjacent to the Town Department of Public Works (the DPW ) building and the contiguous area to the west of the DPW building where waste was burned prior to The Landfill s present abutters are: the DPW building and it s garage to the north, the Town cemetery to the south, vegetated wetlands to the west, and residential housing to the east. In October 1994, Nagle Consulting Associates, Inc. (NCA) submitted an Initial Site Assessment/Comprehensive Site Assessment Scope of Work (ISA/CSA SOW) and an original Comprehensive Site Assessment (CSA). A Supplemental Comprehensive Site Assessment (the SCSA ), dated September 2004, was prepared on behalf of the Town of Halifax by Brown and Caldwell Environmental Engineers & Consultants of Middleborough, Massachusetts, for the Hemlock Lane Landfill. MassDEP determined that the SCSA was administratively and technically complete, and Conditionally Approved the SCSA on April 5, Prior to capping, the Landfill was used for storage of soil materials and for a Town operated composting facility. The storage of these materials and the associated traffic dynamically loaded the Landfill. Based on this dynamic loading and the twenty-nine (29) years since waste disposal occurred, minimum additional settlement is anticipated at the Landfill. A Corrective Action design application (BWP SW 25, Transmittal No. W072797) was submitted to MassDEP on April 27, 2006 and approved by MassDEP on August 3, The Landfill final cover system was designed to incorporate continued use of the Landfill for a Town operated compost facility and Department of Public Works materials storage. A Post Closure Use permit application (BWP SW 36 Transmittal No. W081550) was submitted to MassDEP on May 17, 2006, and approved on August 15, MassDEP approved the use of the Landfill for composting operations and Department of Public Works materials storage. On May 7, 2008, MassDEP issued a review of an Assessment of Landfill Cover System submitted pursuant to the requirements of the PCU approval to perform ambient air sampling of the post closure site conditions.

3 Final Cover System Description The Town constructed a final cover system over waste materials disposed at the Landfill after the Landfill was re-shaped for closure. The sideslopes of the Landfill were re-graded to a maximum slope of 1-foot vertical rise to 3-foot horizontal run. The Landfill top was constructed at a minimum slope of three percent. Although the regulatory minimum standard is five percent for final slopes, MassDEP determined that three percent was appropriate for this location based on the waste age of over twenty-nine years and prior Landfill use as a compost site. Traffic and stockpiling of compost materials has effectively surcharged the Landfill limiting the potential for further settlement. Two final cover system designs were used at the Landfill. One system was constructed on areas of the Landfill where no post closure use is intended and includes a vegetative cover system. In areas where vehicles will operate on the Landfill during post closure use, the final cover system has been designed with a gravel surface designed to accommodate vehicular traffic. The final cover system in the vegetated areas is comprised of the following: a prepared subgrade of compacted soil materials (daily and intermediate cover material); an overlying gas venting layer consisting of a minimum thickness of six inches (6 ) of soil with a minimum saturated hydraulic conductivity of 1x10-3 centimeters per second (cm/sec); an overlying low permeability layer consisting of a forty (40) mil textured high-density polyethylene (HDPE) textured geomembrane, flexible membrane liner ( FML ); an overlying drainage layer consisting of soil with a minimum thickness of nine inches (9 ) and a minimum saturated hydraulic conductivity of 5x10-3 cm/sec with a perforated pipe subdrain system constructed within the drainage soil; and an overlying vegetative support layer comprised of a minimum thickness of nine inches (9 ) of soil, with a maximum permeability of 1.2x10-4 cm/sec, a minimum organic content of eight (8) per cent, capable of maintaining a healthy vegetative growth on the final cover and seeded with vegetative cover seed mix. The final cover system in the gravel surface areas is comprised of the following: a prepared subgrade of compacted soil materials (daily and intermediate cover material); an overlying gas venting layer consisting of a minimum thickness of six inches (6 ) of soil with a minimum saturated hydraulic conductivity of 1x10-3 centimeters per second (cm/sec); an overlying low permeability layer consisting of a forty (40) mil textured high-density polyethylene (HDPE) textured geomembrane, flexible membrane liner ( FML ); an overlying drainage layer consisting of soil with a minimum thickness of nine inches (9 ) and a minimum saturated hydraulic conductivity of 5x10-3 cm/sec with a perforated pipe subdrain system constructed within the drainage soil; an overlying subgrade layer consisting of a minimum of fifteen inches (15 ) of structural subgrade soil, and on overlying gravel road base layer consisting of a minimum of twelve inches (12 ) of road base material.

4 In order to facilitate post closure use of part of the Landfill for composting operations and Department of Public Works materials storage, a twenty-seven inch (27 ) thick layer of soil was constructed above the nine inch (9 ) thick sand drainage layer, for a total soil thickness of thirty-six inches (36 ). Warning strips, consisting of orange litter/snow fencing, were placed below the miscellaneous materials storage area. These strips were placed twelve inches (12 ) below the surface grade and alert the facility operator if excessive cover soils are excavated during post closure use activities. The location of the warning strips are as shown on a drawing prepared by Lynnfield Engineering, titled Halifax Landfill dated November 2007, and revised on January 15, 2008 to illustrate the warning strip locations. The miscellaneous materials storage area will consist of ten bays approximately twenty feet wide by twenty feet long, constructed of two foot by two foot by six foot concrete blocks place four (4) to eight (8) feet high. These barriers are planned to be placed by the Town prior to use of the storage areas. Stormwater Control Stormwater runoff controls were implemented to maintain the integrity of the final cover, prevent ponding of water on the areas of final cover, and control stormwater runoff to prevent off-site impacts. The stormwater control system includes drainage swales along the inside edge of an access road to be constructed in the southwestern corner of the Landfill, and on the northern and eastern side slopes. A detention basin was constructed located at the southwest corner. The detention basin includes a series of baffles and an outlet to adjacent wetlands. A Notice of Intent ( NOI ) was submitted to the Halifax Conservation Commission on May 5, Calculations included within the NOI demonstrate that for the 2-year, 10-year, and 100-year storm events, postconstruction storm water runoff rates to the wetlands are less than pre-construction runoff rates. Drainage pipes consisting of four-inch (4 ) diameter perforated pipe were installed across the western side slope at a spacing of approximately fifty feet to collect stormwater accumulated with in the sand drainage layer. Side slope pipes connect to twelve-inch (12 ) diameter perforated HDPE header pipe installed down the side slope leading to stone lined perimeter swales. Landfill Gas Control Gases generated by waste decomposition within the Landfill are managed using a passive landfill gas collection system. Six individual passive wells were constructed consisting of a twenty-four inch (24 ) diameter boring extending approximately thirty inches (30 ) into the waste. At five of these locations, twelve inch (12 ) deep vent trenches were constructed extending ten feet in two opposite directions. Perforated four inch (4 ) diameter Schedule 40 PVC pipe was placed into the boring and the trenches and covered with washed stone. At one passive vent located in the vicinity of the salt shed, the vent trench was extended fifty-feet in each direction. Two additional gas collection and vent trenches were constructed in the area of the gravel final cover system. One trench extends approximately 300 feet along the ridge line. A second vent trench extends approximately 160 feet and parallels Hemlock Lane. Each trench incorporates one vertical vent pipe at one end of the trench.

5 To minimize the subsurface migration of landfill gas, a gas barrier trench was constructed along the landfill southern and eastern sides. The trench extends down to the level of average groundwater to create a seal to prevent the landfill gas from migrating laterally. The outer trench wall is lined with a forty (40) mil geomembrane barrier. A geocomposite layer acting as a preferential pathway for landfill gas was placed along the bottom, outer side and top of the trench. The trench was backfilled with excavated material with two feet (2 ) of crushed stone at the top. A perforated schedule 40 PVC pipe was placed within the crushed stone to vent landfill gas. Landfill Gas Monitoring Monitoring of subsurface landfill gas migration has indicated that landfill gas has migrated to the north of the Landfill as evidenced by detection of landfill gas in gas monitoring wells GV-7 and GV-8. Gas monitoring well GV-7 is located between the Landfill and a gasoline depot with underground tanks, gasoline piping and electrical conduits. The Town has not elected to extend the landfill gas cutoff trench into the vicinity of the gasoline depot at this time but is further evaluating the potential for adverse impacts of landfill gas in this area. Gas monitoring wells GV-7 and GV-8 are located between the landfill and the existing highway garage. The Town must determine the extent of subsurface landfill gas migration each monitoring period. The Town installed one permanent gas monitoring well between GV-7 and the highway garage and a second new gas monitoring well between GV-8 and the highway garage. If landfill gas is detected in a new monitoring well, additional actions must be taken to determine the extent of migration within the soil and the highway garage must be monitored. The Town must determine the extent of subsurface gas migration with temporary probes. MassDEP reserves the right to require mitigative measures to prevent landfill gas migration should the potential for adverse impact be determined to exist. Approval with Conditions As a result of its review, MassDEP has determined that the submitted documents are satisfactory and in accordance with the authority granted pursuant to Chapter 111, Section 150A of the Massachusetts General Laws hereby approves the construction certification reports listed above for the Town of Halifax, Hemlock Lane Landfill subject to the following conditions. 1. Pursuant to 310 CMR , the Town shall record notification in the Registry of Deeds that a landfill has been operated on the site. A copy of the recorded notification shall be forwarded to MassDEP within sixty (60) days of the date of this approval. 2. The Town shall maintain, care for and monitor the site during the post-closure period in accordance with 310 CMR Pursuant to 310 CMR (2), the post-closure period shall extend for a minimum of a 30-year period from the date of this certification, unless the post closure period is modified by MassDEP pursuant to 310 CMR (3 or 4) 3. During the post closure period, the Town shall maintain the Environmental Control and Monitoring Systems in accordance with 310 CMR and maintain the site in accordance with 310 CMR (5).

6 4. The post-closure period shall end on the date of MassDEP s written determination that the post-closure care, maintenance and monitoring of the site are no longer required. Said written determination in no way limits or absolves the Town of liability for the site in the future. 5. A bi-annual report shall be submitted to MassDEP s Southeast Regional Office Solid Waste Management Section by February 15 th of every second year beginning in the year Pursuant to 310 CMR (6) Reporting Requirements, the report shall describe any activity at the site and summarize the results of the environmental monitoring programs. 6. When the final Post-Closure Maintenance and Monitoring Plan ( Plan ) is approved, environmental monitoring shall be conducted in accordance with the approved Plan. 7. The closed Landfill site shall not be used for any purpose without the prior written approval of MassDEP. 8. The Town has placed warning strips in strategic locations within the Landfill final cover system. The Town shall not use any Landfill final cover area without warning strips for the storage of compost materials or DPW related materials. Should the Town desire to use additional areas, a permit application to add additional warning strips must be submitted for MassDEP review and approval. MassDEP reserves the right to require additional assessment or action as deemed necessary in order to protect and maintain the environment free from objectionable nuisances, dangers and/or threats to public health. Right to Appeal This approval has been issued pursuant to M.G.L. Chapter 111, Section 150A, and 310 CMR : Procedure for Existing Facility Permits, Permit Modifications, Permit Renewals and other Approvals, of the Solid Waste Management Regulations. Pursuant to 310 CMR (5), any person aggrieved by the issuance of this determination may file an appeal for judicial review of said decision in accordance with the provisions of M.G.L. Chapter 111, Section 150A and M.G.L. Chapter 30A not later than thirty days following receipt. Notice of Appeal - Any aggrieved person intending to appeal the decision to the superior court shall provide notice to MassDEP of the intention to commence such action. Said notice of intention shall include MassDEP File Number W and shall identify with particularity the issues and reason (s) why it is believed the approval decision was not proper. Such notice shall be provided to the Office of General Counsel of MassDEP and the Regional Director for the regional office that made the decision. The appropriate addresses to send such notices are:

7 Office of General Counsel Department of Environmental Protection One Winter Street Boston, MA David Johnston Acting Regional Director Department of Environmental Protection 20 Riverside Drive Lakeville, MA No allegation shall be made in any judicial appeal of this decision unless the matter complained of was raised at the appropriate point in the administrative review procedures established in those regulations, provided that matter may be raised upon showing that it is material and that it was not reasonably possible with due diligence to have been raised during such procedures, or that matter sought to be raised is of critical importance to the public health or environmental impact of the permitted activity. If you have any questions regarding this issue, please contact me at (508) or Dan Connick at (508) or at the letterhead address. Very truly yours, David B. Ellis, Chief Solid Waste Management Section E/DC/rr C:\Documents and Settings\Rreimao\Local Settings\Temporary Internet Files\OLK6F\Halifax LF Closure Cert 6-08.doc fc: Halifax (781) Board of Selectman 499 Plymouth Street Halifax, MA Halifax DPW Director Hemlock Lane Halifax, MA ec: Halifax Board of Health ATTN: Cathy Drinan Brown and Caldwell ATTN: Gerald Cushing DEP-Boston ATTN: J. Doucett