N.H. Admin. Code § Env-Sw 805.06

Current through Register No. 50, December 12, 2024

Section Env-Sw 805.06 - Leachate Collection and Removal System Design Standards

(a) Leachate collection and removal systems shall be required at all lined landfills, to collect and remove leachate contained within each liner system in conformance with Env-Sw 806.05.

(b) Leachate collection and removal systems shall be designed to be hydraulically separate from the stormwater management system(s).

(c) Leachate collection and removal systems shall be designed to function effectively during freezing and frozen-ground conditions.

(d) Leachate collection and removal systems shall be designed to function effectively during both the active life of the landfill and the landfill closure and post-closure period. Therefore, for the purpose of sizing the system(s) components and specifying materials with an appropriate design life expectancy, the leachate generation rates and volumes for the above specified time period shall be considered.

(e) Leachate collection and removal systems shall be designed to maintain one foot or less of hydraulic head on all portions of the liner, excluding the leachate collection sumps if any, during routine operations including the 25-year storm event with a duration equivalent to the time of concentration of the drainage area of the component being sized.

(f) Leachate collection and removal systems shall be designed to manage the quantity of leachate to be generated by the 100-year storm event with a duration equivalent to the time of concentration of the drainage area which contributes to leachate generation, in a manner which shall:

(1) Not allow a hydraulic head greater than one-foot to exist on any portion of the liner system, excluding the leachate collection sumps, if any, for longer than 7 days;

(2) Provide storage and removal capabilities determined in accordance with (g) below if for a facility not directly connected to a permitted wastewater treatment facility or in accordance with (h) below if for a facility directly connected to a permitted wastewater treatment facility; and

(3) Not rely on leachate recirculation as a factor in determining the required storage and removal capabilities, even if leachate recirculation will be a routine operating procedure at the facility.

(g) Leachate collection and removal systems which are not directly connected to a permitted wastewater treatment facility shall provide capacity for storing leachate as follows:

(1) At least 15% of the 100-year storm storage volume, as specified by (f) above, shall be provided in primary storage units located outside the waste deposition area or in sumps located within the waste deposition area;

(2) The number of walls or liners in the primary storage units shall be no less than the number of liners within the landfill; and

(3) Containment for the volume of leachate produced by the 100-year storm event which exceeds the volume of the primary storage units shall be provided:

a.Within contingency storage units located outside the waste deposition area, which shall be leak tight and accessible for leak testing, inspection and repair, but not necessarily multi-walled; and

b.On the uppermost liner within a waste deposition area provided that:

1.Storage on the liner in excess of one-foot of hydraulic head shall be limited to a period of 7 days or less, based on procedures identified in the leachate management plan provided pursuant to Env-Sw 806.05, including the pumping and removal rates required to reduce the hydraulic head within 7 days and the specifications for the equipment required to do so; and

2.Systems relying on valve closure to initiate storage on the liner shall be fully equipped with automated notification alarms to minimize the potential for overflow, in accordance with (p) below.

(h) Leachate collection and removal systems which are directly connected to a permitted wastewater treatment facility shall be designed as follows:

(1) The system shall provide leachate storage units outside the waste deposition area as necessary to meet the requirements of (f) above based on the allowable discharge rate of leachate to the wastewater treatment facility, pump capabilities and other such factors which limit the rate at which leachate removal can occur;

(2) Compatible pumping and removal rates shall be provided as a component of the facility's leachate management plan, pursuant to Env-Sw 806.05; and

(3) Systems relying on valve closure to initiate storage shall be fully equipped with automated notification alarms to minimize the potential for overflow, in accordance with (p) below.

(i) The various components of a leachate collection and removal system shall:

(1) Be chemically compatible with the anticipated waste and leachate characteristics;

(2) Provide access for monitoring flow, monitoring hydraulic head in the uppermost liner system, controlling flow and cleaning;

(3) Maintain integrity under both dynamic and static loading events for all phases of landfill development;

(4) Specify geotextiles based on calculations which incorporate the leachate generation and flow rates anticipated to occur during the operating and post-closure phases of the landfill; and

(5) Be designed to prevent the passage of fine particulates into the leachate collection and piping systems as well as mitigate against or eliminate the effects of any material capable of reducing the hydraulic flow capacity of the leachate collection and piping systems.

(j) Pipes which require solvent welding shall not be used.

(k) The drainage blanket shall:

(1) Be designed to meet the requirements of (e) and (f) above;

(2) Contain no more than 15% calcium carbonate to prevent deposition and clogging and otherwise be of a quality that shall not result in clogging of the leachate collection and removal system(s); and

(3) Be constructed in accordance with a quality assurance/quality control plan established pursuant to Env-Sw 805.16.

(l) A facility shall not be designed to rely solely on managing leachate by recirculation methods.

(m) Recirculation of leachate, if practiced, shall proceed only in accordance with the provisions of a leachate recirculation plan approved by the department as part of the facility's operating plan pursuant to Env-Sw 1105 based on the criteria in Env-Sw 806.05.

(n) Leachate collection and removal systems which depend on routine pumping, rather than gravity operating methods, shall only be used at facilities where a full-time operator shall be present during normal operating hours and where auxiliary power and pumping equipment shall be available.

(o) Pump stations located outside the waste deposition area shall be designed to provide the following:

(1) Backup pumping capacity;

(2) Backup power supply;

(3) High-water alarm; and

(4) Efficient operation during both average and peak flows.

(p) Tanks, sumps or other storage units associated with leachate collection and removal systems shall be equipped with high-water alarms.

N.H. Admin. Code § Env-Sw 805.06

#5172, eff 7-1-91; ss by #6535, INTERIM, eff 7-1-97, EXPIRES: 10-29-97; ss by #6619-B, eff 10-29-97; (See Revision Note at chapter heading for Env-Sw 800) ss by #8459, eff 10-28-05 (formerly Env-Wm 2505.06 )

Amended byVolume XXXIV Number 24, Filed June 12, 2014, Proposed by #10597, Effective 7/1/2014, Expires7/1/2024.