Alternative Groundwater Protection System Design, and 310 CMR 19.114: Ground

Water Protection System and Final Cover Waivers, ground water protection systems shall consist, at a minimum, of: (a) a sub-grade layer; (b) a secondary composite liner; (c) a leak detection and secondary collection system; (d) a primary liner; (e) a drainage layer or layers; (f) a leachate collection system; and (g) a leachate storage system unless the leachate collection system is to be directly connected to a sewer system. (4) Minimum Liner Configuration. (a) For any area where the slope of the liner will be less steep than four horizontal to one vertical (<4:1) and for the first five feet vertically on perimeter berms or side slopes, if any, the landfill liner shall, at a minimum, be comprised of a double composite liner consisting of: 1. a primary composite liner consisting of: a. one foot of a low permeability compacted soil layer or admixture overlain by a flexible membrane liner (FML); or, b. a geosynthetic clay liner (GCL) overlain by a flexible membrane liner (FML); 2. a leak detection and secondary collection system located between the primary and secondary liner; and 3. a secondary composite liner consisting of: a. two feet of a low permeability compacted soil layer or admixture overlain by a flexible membrane liner (FML); or, b. one foot of a low permeability compacted soil layer overlain by a geosynthetic clay liner (GCL) and a flexible membrane liner (FML). (b) For any area where the slope of the liner will be steeper than or equal to four horizontal to one vertical ($4:1) the landfill liner shall, at a minimum, be comprised of a double liner consisting of: 1. a liner configuration that conforms to 310 CMR 19.110(4)(a); or 2. a double composite liner consisting of: a. a primary composite liner consisting of a geosynthetic clay liner (GCL) overlain by a flexible membrane liner (FML) b. a leak detection and secondary collection system located between the primary and secondary liner; and c. a secondary composite liner consisting of one foot of a low permeability compacted soil layer or admixture overlain by a flexible membrane liner (FML); or 3. a double liner consisting of: a. a primary liner consisting of a FML; b. a leak detection and secondary collection system located between the primary and secondary liner; and c. a secondary composite liner consisting of: i. two feet of a low permeability compacted soil layer or admixture overlain by a flexible membrane liner (FML); or ii. one foot of a low permeability compacted soil layer overlain by a geosynthetic clay liner (GCL) overlain by a FML. (c) Any FML layer shall be constructed so that the FML material is in direct contact with the low permeability soil layer or GCL layer directly below it. Where the GCL layer is to be used in conjunction with a low permeability soil layer, the GCL layer shall be constructed so that the GCL material is in direct contact with a the low permeability soil layer. Liner components shall meet the design and performance criteria specified at 310 CMR 19.110(6) through (11). (5) Vertical Expansions over Existing Fill. The following requirements apply when a permit review and approval is needed from the Department prior to placing additional waste vertically (hydraulically upgradient) over previously landfilled areas with an existing liner system (or where there is no liner) that does not comply with the groundwater protection system requirements at 310 CMR 19.110(3) and (4). Waste that is being placed in areas under an existing valid Authorization to Operate permit are not subject to 310 CMR 19.110(5) until the capacity represented by that approval is exhausted. (a) Areas Where there is no Existing Liner. Vertical expansions that will place waste over an area that has no underlying groundwater protection system will be required to construct a liner system in full compliance with 310 CMR 19.110(3) and (4). (b) Areas Where there is an Existing Single Liner. Vertical expansions that will place waste over an area that has an existing single liner (such as a soil only or FML only liner) will be required to construct a liner system in full compliance with 310 CMR 19.110(3) and (4). (c) Areas Where there is an Existing Single Composite Liner or a Double Liner that is not a Double Composite Liner. 1. Performance Standard. A hydraulic separation layer shall be constructed using technologies or components that will result in a system that prevents, to the maximum extent possible, leachate generated in areas approved after the effective date of these regulations from mixing with leachate collected in areas approved prior to these regulations. In general, such systems shall use combinations of low permeability barriers and high capacity drainage systems. All leachate intercepted by the hydraulic separation layer shall be directed to and collected in a lined area designed in accordance with the requirements of 310 CMR 19.110(4). 2. Design Standard. For facilities disposing of municipal solid waste (MSW) over an existing single composite liner functioning as designed, where the expansion area will operate for approximately two years or longer before installing a cap, and where the slope of the hydraulic separation layer will be equal to or steeper than 4:1, the presumptive design standard to meet the performance standard above shall be a single liner consisting of: a. a FML; or b. a GCL; or c. 18 inches of soil with a maximum permeability of 1x 10 cm/sec; and -7 d. a high performance drainage layer consisting of 12 inches of soil with a permeability no less than 1 x 10 cm/sec or 12 inches of less permeable soil in -3 combination with a synthetic drainage layer such as a geonet. In situations where the slope of the liner to be constructed over an existing composite liner is less steep than 4:1, the presumptive design standard shall be a liner in accordance with 310 CMR 19.110(4). 3. Further Considerations. In situations where the assumptions listed above at 310 CMR 19.110(5)(c)2. do not apply, the Department may approve alternative designs that have different requirements than the presumptive design standard. The Department will not approve an alternative design unless the applicant provides sufficient information to the Department’s satisfaction that an alternative design will be as protective of the public health, safety and the environment as the presumptive design. a. More Stringent Requirements. Examples of when more stringent liner requirements, such as double liners with leak detection, will be the presumed requirement: i. where an existing liner is not operating properly; ii. where the slope of the separation layer will be less steep than 4:1; iii. where the landfill is located in a sensitive environmental location such as a sole source aquifer. b. Less Stringent Requirements. Examples of when less stringent requirements may be considered by the Department: i. where MSW ash, C&D waste or other single source waste types are being disposed and characteristics of the waste such as permeability, leachate quality or other characteristics of the waste are considered; ii. where the operating time in an area, before capping, will be less than two years (segmentation of project length is not allowed); iii. where an existing double liner underlines the affected area. (d) Areas Where there is an Existing Double Composite Liner. The Department may require the installation of a hydraulic separation layer between vertical or horizontal sections or phases of a double composite lined landfill to isolate such areas for purposes of separately monitoring the performance of the groundwater protection systems in those discrete areas. (e) Notwithstanding the requirements at 310 CMR 19.111(1), alternative designs may be reviewed subject to the equivalency review requirements at 310 CMR 19.105 or other requirements as determined by the Department. (6) Subgrade Layer Standards. (a) Performance Standard. The subgrade layer shall provide adequate structural support for the ground water protection system and the solid waste disposed in the landfill; (b) Design Standards. The subgrade layer shall: 1. be compacted, uniform and free of debris, angular rocks, plant materials and other foreign materials that may damage low permeability liner materials; and 2. be of sufficient thickness to ensure a minimum of four foot separation between the top of bedrock or the maximum high ground water table, as determined using acceptable methods, and the bottom of the lowermost low permeability layer. (7) Low Permeability Layer (Liner) Standards. (a) Performance Standards. A low permeability layer shall: 1. minimize to the greatest practicable extent the movement of leachate through the liner; 2. be designed and constructed to meet the permeability design standard for the expected life and post-closure period of the facility; and 3. be constructed in accordance with the quality assurance and quality control requirements of 310 CMR 19.106. (b) Design Standards. 1. Low Permeability Soil/Admixture Layer Standards. Compacted low permeability soil or admixture layers shall: a. have a minimum thickness of one foot when used in the primary composite liner or have a minimum thickness of two feet when used in the secondary composite liner unless a GCL is used in the secondary liner, or the secondary liner slope is greater than or equal to a 4:1 slope, then only one foot is required; b. have a maximum in-place saturated hydraulic conductivity of 1 x 10 cm/sec. -7 throughout the entire thickness of the layer; c. have a minimum post-settlement slope of two percent; d. be free of materials that because of their physical, chemical or biological characteristics may cause or contribute to an increase in the permeability of the liner or otherwise cause a failure of the liner; and e. be compacted to minimize void spaces and support the weight imposed by the waste disposal operations without settling so as to cause or contribute to the failure of the liner or leachate collection system. 2. Flexible Membrane Liner Standards. Flexible membrane liners shall: a. be of sufficient thickness as determined by the Department; b. be constructed to ensure that the seams connecting FML panels are of equal or greater strength than the panels or manufacturer's seams within panels and are oriented, as much as is practical, parallel to the slope and not across the slope; c. have sufficient flexibility and strength for the proposed application, taking into consideration tensile strength, puncturability, stress cracking and chemical compatibility; and d. be capable of being seamed to produce leak-tight, high- strength seams that retain their integrity during liner installation, operating life and the post-closure period. 3. Geosynthetic Clay Liners (GCLs) Standards. Geosynthetic clay liners shall: a. have sufficient bentonite (or similar low permeability clay) to provide an effective low permeability layer; b. be constructed to ensure that the bentonite (or similar low permeability clay) will be distributed and retained uniformly and securely throughout the GCL during the operating life and the post-closure period; c. have sufficient durability for the proposed application, taking into consideration hydration, chemical compatability, desiccation and other considerations that may affect initial or long term performance; and d. be capable of being seamed or joined per standard industry practice to produce leak-tight connections that retain their integrity during the operating life and the post- closure period. (8) Drainage/Protection Layers. (a) Performance Standard. Drainage/protection layers shall: 1. provide continuous and freeflowing drainage over the entire liner; and 2. provide adequate protection to the liner from equipment and solid waste disposed in the landfill. (b) General Design Standards. The drainage/protection layer shall use materials and be designed and constructed so that: 1. the drainage layer will not become clogged or in any other way be impaired from allowing free-flowing drainage of leachate; 2. when used as a part of the primary leachate collection system the layer shall; a. have a minimum thickness of 18 inches; b. when a soil is used, the lower 12 inches has a minimum in-place hydraulic conductivity of 1 x 10 cm/sec and the upper six inches has a minimum hydraulic -2 conductivity of 1 x 10 cm/sec; or -3 c. when a synthetic drainage layer is used, it shall be designed in accordance with 310 CMR 19.110(8)(c); and d. be designed in accordance with 310 CMR 19.110(9). 3. when used as a part of a secondary leachate collection or leak detection system the layer shall; a. have a minimum thickness of 12 inches with a minimum in-place hydraulic conductivity of 1 x 10 cm/sec when a soil is used; or -2 b. be a synthetic drainage layer designed in accordance with 310 CMR 19.110(8)(c); and c. be designed in accordance with the 310 CMR 19.110(8). 4. the integrity of the layer is maintained by preventing the infiltration of fine material by being bound, as necessary, on its upper and/or lower surfaces with filter material, such as a geotextile filter fabric. (c) Synthetic Drainage Material (Geonet) Design Standards. In addition to the standards specified at 310 CMR 19.110(7)(a) and (b), geonets used as a part of a drainage /protection layer shall: 1. be of sufficient strength to prevent deformation and impairment of function by the weight of vehicles and the solid waste to be disposed; 2. have sufficient flow capability; 3. be designed and evaluated for its effective long-term flow capacity using reasonable and acceptable evaluation methods that consider factors that may reduce (reduction factors) the design flow capacity caused by, but not limited to, overburden forces, (deformation, creep, etc.),intrusion by overlying materials such as filter fabrics or soil, and chemical or biological clogging; and 4. be designed with an overall safety factor (for flow capacity) appropriate to ensure the effective long-term performance of the drainage layer. (9) Leak Detection and Secondary Collection Systems Between Liners. (a) Performance Standards. Leak detection and secondary leachate collection systems shall provide for detection of leakage of leachate through the primary or uppermost liner and the collection and removal of leachate from the secondary liner. (b) Design Standards. A leak detection and secondary collection system shall be designed: 1. to collect and remove leachate discharged into a drainage layer between the primary and secondary liners with an efficiency so that a leakage rate of ten gallons per day/per acre, or greater, will be detected within 24 hours of initial saturation; 2. to the extent feasible, identify the general location of the leak; 3. to allow the quantity and quality of leachate, or any liquid, in the leak detection system, to be measured and analyzed separately from the leachate in the primary leachate collection system; 4. with an Action Leakage Rate (ALR) which shall be reasonable and appropriate based upon the design and components of the double liner system; 5. so that the head in the secondary collection system will not, in general, exceed the thickness of the drainage layer between the liners; and 6. with a leak response plan that details the actions to be taken to evaluate and, when required, eliminate the cause of the leak. (c) Action Leakage Rate (ALR). 1. The maximum action leakage rate shall be 100 gallons per acre/day, based on a 30- day rolling average (any consecutive 30 day period), unless the Department has established another action leakage rate for that facility, phase or operational period; 2. An ALR shall be identified for each stage of the operational life of the liner system; 3. Where leakage into the leak detection system is occurring at a rate greater than one half the ALR, the owner or operator of the facility shall notify the Department in writing within 72 hours. Such notification needs only to be made once in any 30 day period. 4. Where a single day leakage rate exceeds twice the ALR, the owner or operator of the facility shall notify the Department, in writing, within 48 hours. 5. In the event of leakage through the primary liner the facility shall take appropriate corrective action based on the quality and quantity of leachate collected or detected as determined by the Department. (10) Primary Leachate Collection and Removal Systems. (a) Performance Standards. Leachate collection and removal systems shall: 1. collect and remove the leachate generated by the landfill as quickly and efficiently as is practicable; 2. provide for the drainage of leachate from the liner into appropriate storage, treatment or transfer facilities; 3. be designed to ensure that the hydraulic head of leachate can be maintained at less than one foot at the expected flow except during storm events and be designed to drop below one foot within seven days of a 25-year storm for the primary operational phase of the landfill. (b) Design Standards. The following design standards shall apply to primary leachate collection systems: 1. pipes shall be placed within a drainage layer in material which meets the standards set forth at 310 CMR 19.110(7); 2. pipes shall have sufficient diameter and spacing to be capable of freely draining the maximum expected leachate flow from the liner; 3. trunk lines shall have a minimum slope of 1%; 4. lateral lines shall have a minimum slope of ½%; 5. pipes shall be of sufficient thickness and strength to support the maximum static and dynamic loads of vehicles and overlying solid waste without failing; 6. piping systems shall be designed with sufficient access points to permit maintenance cleaning as necessary; 7. the number of penetrations of the liner shall be minimized. Penetrations of the liner shall be properly sealed to prevent leakage and wherever possible be designed with access so as to repair damaged seals; and 8. all sump areas shall be designed to allow access for maintenance of pumps and, at a minimum, provide for remote inspection. (11) Leachate Storage Facilities. (a) Performance Standard. Leachate storage facilities shall provide for leak-tight storage of the leachate reasonably expected to be generated by the landfill. (b) Design Standards. Leachate storage facilities shall: 1. conform to the criteria established by the Department's regulations for industrial wastewater holding facilities, 314 CMR 18.00: Industrial Wastewater Holding Tank and Container Construction Operation and Recordkeeping Requirements; 2. have sufficient strength to ensure that the tank does not collapse or rupture; 3. be located outside the landfill liner system; 4. have sufficient capacity to store the leachate generated by the landfill; 5. be designed with a monitoring device to accurately monitor the volume of liquid collected within the storage facility and be equipped with a system capable of warning the operator when the tank requires pumping; and 6. incorporate secondary containment or a leak detection system.