N.M. Admin. Code § 20.9.4.15 - LEACHATE COLLECTION SYSTEMS FOR LANDFILLS

A. Except as specified in 20.9.2.14 NMAC and Subsection C of 20.9.4.13 NMAC, all new municipal and special waste landfills and lateral expansions shall include a leachate collection system, which shall be designed by a professional engineer licensed to practice in New Mexico, and which shall incorporate a piping collection network comprised of perforated pipe having a minimum diameter of 6 inches and a minimum wall thickness of schedule 80 PVC or equivalent and shall be designed and constructed to:

(1) maintain less than a one-foot depth of leachate on the liner;

(2) maintain a minimum of two percent slope throughout the system, within the lined landfill cell; an alternate slope may be specifically approved by the secretary for leachate conveyance piping outside the disposal cell footprint;

(3) withstand chemical attack from waste and leachate; and

(4) withstand the loads, stresses, and disturbances from overlying waste, waste cover materials, and equipment operation.

B. Any geosynthetic materials such as geonets and geotextiles, if used as components of the leachate collection system, must have a hydraulic conductivity, transmissivity and chemical and physical qualities that will not be adversely affected by waste placement, equipment, operation, or leachate generation. These geosynthetics, if used and operating in conjunction with the soil protective cover for the liner as described in Paragraph (4) of Subsection E of 20.9.4.13 NMAC, must have a hydraulic conductivity and transmissivity designed to ensure the hydraulic head on the liner never exceeds one foot.

C. A written leachate management plan shall be submitted for approval by the secretary. The plan shall describe anticipated amounts of leachate, duration of generation and final disposal options for the leachate and shall include:

(1) a description of the means of analysis; and

(2) a description of the type of treatment and proposed disposal method.

D. Leachate storage and collection ponds shall be designed to meet the requirements of 20.9.4.13 NMAC. A pond may be designed to maintain greater than one foot of leachate, provided it is equipped with a double, composite liner as specified in 20.9.4.13 NMAC, or an alternative design providing equivalent protection and approved in the permit.

Notes

N.M. Admin. Code § 20.9.4.15

20.9.4.15 NMAC - Rp, 20 NMAC 9.1.III.308, 08/02/07