N.M. Admin. Code § 20.9.6.9

Current through Register Vol. 35, No. 23, December 10, 2024

Section 20.9.6.9 - CLOSURE AND POST-CLOSURE REQUIREMENTS FOR MUNICIPAL AND SPECIAL WASTE LANDFILLS, AND MONOFILLS

A. Owners and operators of municipal landfills and special waste landfills shall begin closure within 30 days after the landfill receives the final receipt of waste or within 30 days after approval of the closure and post-closure care plan, whichever is later.

(1) Owners and operators shall install a final cover system which consists of the following:

(a) for municipal and special waste landfills (except monofills) that are not lined and which never received more than 7,300 tons of waste (i.e., an average of 20 tons or less per day annual average) during any calendar year, an infiltration layer comprised of a minimum of 18 inches of earthen material having a saturated hydraulic conductivity no greater than 1 x 10^-5 cm/sec;

(b) for municipal landfills which exceed the tonnage requirements of Subparagraph (a) of this paragraph and for all special waste landfills (other than monofills), an infiltration layer comprised of a minimum of 18 inches of earthen material having a saturated hydraulic conductivity less than or equal to the saturated hydraulic conductivity of any bottom liner system or natural subsoils present, or a saturated hydraulic conductivity no greater than 1 x 10^-5 cm/sec., whichever provides for less infiltration;

(c) a layer for minimizing erosion consisting of a minimum of six inches of earthen material that is capable of sustaining native plant growth;

(d) any necessary gas vents provided they are sealed to assure no water infiltration;

(e) finished grades over filled areas which shall not exceed 25 percent (four feet horizontal to one foot vertical), or be less than five percent for new landfills and lateral expansions permitted for construction, operation, and closure after the effective date of these regulations or two percent for all other landfills;

(f) run-off controls designed for a peak discharge of a 24-hour, 25-year storm;

(g) cover material compacted to no less than 75 percent and no more than 85 percent standard proctor density unless otherwise approved in the permit, closure plan or by specific approval; and

(h) for closure of a cell containing only regulated asbestos waste or scrap tires, the owner or operator shall cover with 30 inches of compacted native soils and 6 inches topsoil on top of the 30-inch cover, to provide a 36-inch final cover to the original grade and implement measures where necessary to control erosion and rodent intrusion.

(2) The secretary may permit an alternative final cover design that includes:

(a) an infiltration layer that achieves an equivalent reduction in infiltration as specified in Subparagraph (a) or (b) of Paragraph (1) of this subsection, as applicable; and

(b) an erosion layer that provides equivalent protection from wind and water erosion as the erosion layer specified in Subparagraph (c) of Paragraph (1) of this subsection;

(c) for landfills that stopped accepting waste prior to the effective date of this part, finished grades different from those specified in Subparagraph (e) of Paragraph (1) of this subsection, provided a demonstration is made that the alternate grades will prevent erosion and will provide equivalent reduction in infiltration; and

(d) for landfills accepting waste after the effective date of this part and lateral expansions permitted after the effective date of this part, finished grades different than those specified in Subparagraph (e) of Paragraph (1) of this subsection, provided no grade is greater than 33 percent and a demonstration is made in the closure plan or permit or modification application that the alternate grades will prevent erosion and will provide equivalent reduction in infiltration.

(3) The written closure plan, at a minimum, shall include the following information:

(a) a schedule for completion of all activities necessary to meet the closure criteria specified in this part;

(b) a report that includes:

(i) a description of the local geology;

(ii) a description of the hydrogeology of the landfill site, including maps and cross-sections illustrating subsurface features;

(iii) well locations, depths to ground water, and, if available, ground water quality, flow direction and gradient shown on a topographic map; and

(iv) a description of the landfill, including:

a) the date operations commenced and the date of final receipt of waste;

b) the types of waste accepted at the landfill;

c) the total volume of waste disposed;

d) a topographic map that shows the size and dimensions of fill areas;

e) a topographic map that shows structures, drainages, and water wells in the area of the landfill; and

f) a topographic map that shows methane monitoring points and methane concentrations along the landfill property boundary and within structures located on landfill property;

(c) a description of the final cover and its placement, including:

(i) thickness and saturated hydraulic conductivity;

(ii) source of the cover material;

(iii) a construction quality assurance/construction quality control plan for placement of the final cover that meets the requirements of 20.9.4.14 NMAC;

(iv) equipment that will be utilized to apply the final cover and ensure it is adequately compacted to obtain the appropriate proctor density; and

(v) a map that shows final contours that meet the requirements of Subparagraph (e) of Paragraph (1) of this subsection;

(d) a vegetation plan, including:

(i) the seeding method to obtain proper growth density; and

(ii) species of vegetation to be planted, including grasses or local seed mix as recommended for the area by the natural resources conservation service for permanent soil stabilization and to minimize wind and water erosion;

(e) a plan to prevent unauthorized access by the public and entry by large animals to the landfill through the use of fences, gates, locks, or other means;

(f) a plan to remove structures, unless otherwise approved by the secretary;

(g) a description of the signs indicating that the site is a closed landfill and no dumping is permitted; all signs shall include the name and telephone number of the landfill owner; and

(h) a post-closure care plan, including:

(i) a monitoring and repair plan that describes methods to be used to ensure cover integrity, including but not limited to settlement, ponding, water erosion, wind erosion, and inadequate drainage, to ensure the final cover meets the slope requirements of 20.9.6.9 NMAC, and to maintain adequate vegetation during the post-closure period;

(ii) a methane monitoring plan in compliance with Subsections B and C of 20.9.5.9 NMAC;

(iii) a ground water monitoring plan; and

(iv) a leachate collection system plan, if applicable;

(4) prior to beginning closure of a landfill, the owner or operator shall notify the secretary that a notice of the intent to close the landfill has been placed in the operating record;

(5) the owner or operator shall complete closure activities in accordance with the closure plan within 180 days following the beginning of closure, unless otherwise approved in the closure plan; extensions of the closure period may be granted by the secretary if the owner or operator demonstrates that closure will, of necessity, take longer than 180 days and has taken and will continue to take all steps necessary to prevent threats to public health, welfare and the environment;

(6) upon completion of closure, a detailed description of the location of areas of waste disposal at the facility, including a plat signed by a registered surveyor, shall be filed with the appropriate county land recording agent; the description and the plat shall be filed so that it will be found during a title search and proof of the filing shall be submitted to the secretary; the description shall perpetually notify any potential purchaser of the property that:

(a) the land has been used as a landfill facility;

(b) its use is restricted as described in the post-closure care plan; and

(7) the owner or operator may request permission from the secretary to file a revised description if all wastes are removed from the facility.

B. Landfill owners or operators shall submit reports of monitoring performance and data to the secretary within 45 days after the end of each calendar year.

C. The post-closure care period for a landfill shall be 30 years.

D. The owner or operator may amend the post-closure care plan, provided the amendment is not a permit modification, by submitting a request to the secretary at least 30 days prior to the proposed change. No proposed amendment shall be effective unless first approved in writing by the secretary.

E. The secretary may require the owner or operator to modify or amend the post-closure care plan if the secretary determines that the present or future implementation of the plan may cause a threat to public health, welfare and or the environment.

N.M. Admin. Code § 20.9.6.9

20.9.6.9 NMAC - Rp, 20 NMAC 9.1.V.502, 8/2/2007