Section 258.62 - Approval of site-specific flexibility requests in Indian country(a)Lake County Municipal Landfill final cover requirements. Paragraph (a) of this section applies to the Lake County Landfill, a municipal solid waste landfill owned and operated by Lake County on the Confederated Salish and Kootenai Tribes' Flathead Reservation in Montana. The alternative final cover request submitted by Lake County, Montana, consisting of the "Lake County Landfill Alternative Cover," dated May 2007, the "Construction Quality Assurance & Control Plan for the Lake County Class II Landfill Unit Landfill Closure Project" and the "Lake County Landfill Plans for Final Closure January 2009," dated January 2009, is hereby incorporated by reference. The Director of the Federal Register approves this incorporation by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 . You may inspect or obtain a copy at the Environmental Protection Agency, Region VIII, Montana Office, 10 West 15th St., Suite 3200, Helena, MT or by calling 406-457-5000. You may also inspect a copy at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. The facility owner and/or operator may close the facility in accordance with this application, including the following activities more generally described as follows:(1) The owner and operator may install an evapotranspiration system as an alternative final cover for the 15.4 acre active area.(2) The final cover system shall consist of a 5.5-feet-thick multi-layer cover system comprised, from bottom to top, of an 18-inch intermediate and gas vent layer, a 24-inch native sand layer, an 18-inch imported silt layer and a 6-inch topsoil layer, as well as seeding and erosion control.(3) The final cover system shall be constructed to achieve an equivalent reduction in infiltration as the infiltration layer specified in § 258.60(a)(1) and (a)(2) , and provide an equivalent protection from wind and water erosion as the erosion layer specified in paragraph (a)(3) of this section.(4) In addition to meeting the specifications of the "Lake County Landfill Alternative Cover" dated May 2007, and the "Construction Quality Assurance & Control Plan for the Lake County Class II Landfill Unit Landfill Closure Project" dated January 2009, the owner and operator shall:(i) At 50% final design, submit to EPA for approval an Operations and Maintenance Plan that includes an inspection schedule (at least quarterly) and remediation plan to address any potential rodent damage to the final cover; and(ii) Achieve re-vegetation rates greater than 50% by the end of the first season and a complete stand of native grasses by the end of the third season.(5) The owner and operator shall place documentation demonstrating compliance with the provisions of this Section in the operating record.(6) All other applicable provisions of 40 CFR part 258 remain in effect.(b)Picacho Municipal Solid Waste Landfill-alternative list of detection monitoring parameters and alternative final cover. This paragraph (b) applies to the Picacho Landfill, a Municipal Solid Waste Landfill operated by Imperial County on the Quechan Indian Tribe of the Fort Yuma Indian Reservation in California. (1) In accordance with § 258.54(a) , the owner and operator may modify the list of heavy metal detection monitoring parameters specified in appendix I of this part, as required during Post-Closure Care by § 258.61(a)(3) , by replacing monitoring of the inorganic constituents, with the exception of arsenic, with the inorganic indicator parameters chloride, nitrate as nitrogen, sulfate, and total dissolved solids.(2) In accordance with § 258.60(b) , the owner and operator may replace the prescriptive final cover set forth in § 258.60(a) , with an alternative final cover as follows:(i) The owner and operator may install an evapotranspiration cover system as an alternative final cover for the 12.5 acre site.(ii) The alternative final cover system shall be constructed to achieve an equivalent reduction in infiltration as the infiltration layer specified in § 258.60(a)(1) and (2) , and provide an equivalent protection from wind and water erosion as the erosion layer specified in § 258.60(a)(3) .(iii) The final cover system shall consist of a minimum three-foot-thick multi-layer cover system comprised, from bottom to top, of:(A) A minimum 30-inch thick infiltration layer consisting of:(1) Existing intermediate cover; and(2) Additional cover soil which, prior to placement, shall be wetted to optimal moisture and thoroughly mixed to near uniform condition, and the material shall then be placed in lifts with an uncompacted thickness of six to eight inches, spread evenly and compacted to 90 percent of the maximum dry density, and shall:(i) Exhibit a grain size distribution that excludes particles in excess of three inches in diameter;(ii) Have a minimum fines content (percent by weight passing U.S. No. 200 Sieve) of seven percent for an individual test and eight percent for the average of ten consecutive tests;(iii) Have a grain size distribution with a minimum of five percent smaller than five microns for an individual test and six percent for the average of ten consecutive tests; and(iv) Exhibit a maximum saturated hydraulic conductivity on the order of 1.0E-03 cm/sec.; and(3) A minimum six-inch surface erosion layer comprised of a rock/soil admixture. The surface erosion layer admixture and gradations for 3% slopes and 3:1 slopes are detailed below: (i) 3% slopes: For the 3% slopes the surface admixture shall be composed of pea gravel (3/8-inch to 1/2-inch diameter) mixed with cover soil at the ratio of 25% rock to soil by volume with a minimum six-inch erosion layer.(ii) For the 3:1 side slopes the surface admixture shall be composed of either: gravel/rock (3/4-inch to one-inch diameter) mixed with additional cover soil as described in paragraph (b)(2)(iii)(A)(2) of this section at the ratio of 50% rock to soil by volume and result in a minimum six-inch erosion layer, or gravel/rock (3/4-inch to two-inch diameter) mixed with additional cover soil as described in paragraph (b)(2)(iii)(A)(2) of this section at the ratio of 50% rock to soil by volume and result in a minimum 12-inch erosion layer.(iii) The owner and operator shall place documentation demonstrating compliance with the provisions of this section in the operating record.(iv) All other applicable provisions of this part remain in effect.(c) City of Wolf Point Municipal Landfill final cover requirements. Paragraph (c) of this section applies to the City of Wolf Point Landfill Phase 2, a municipal solid waste landfill owned and operated by the City of Wolf Point on the Assiniboine and Sioux Tribes' Fort Peck Reservation in Montana. The facility owner and/or operator may close the facility in accordance with this application, including the following activities more generally described as follows: (1) The owner and operator may install an evapotranspiration system as an alternative final cover for the 3.5-acre Phase 2 area.(2) The final cover system shall consist of a 4-foot-thick multi-layer cover system comprised of the following from bottom to top: A 12-inch intermediate layer, a 24-inch native silty-clay till layer, and a 12-inch native topsoil layer, as well as seeding and erosion control.(3) The final cover system shall be constructed to achieve an equivalent reduction in infiltration as the infiltration layer specified in § 258.60(a)(1) and (a)(2) , and provide an equivalent protection from wind and water erosion as the erosion layer specified in paragraph (a)(3) of this section.(4) In addition to meeting the specifications of "The City of Wolf Point Landfill License #3-Phase 2 Alternative Final Cover Demonstration (Revised)" application of February 9, 2016, the owner and operator shall:(i) At finalization, submit to the EPA for approval final cover plans and specifications, including the final Construction Quality Assurance/Quality Control Plan and final Closure/Post-Closure Plan; and(ii) Achieve re-vegetation rates greater than 75% by the end of the third year after revegetation.(5) The owner and operator shall place documentation demonstrating compliance with the provisions of this section in the operating record.(6) All other applicable provisions of 40 CFR part 258 remain in effect.(d)Cocopah Municipal Solid Waste Landfill-Alternative final cover and alternative location for the storage of facility records. This paragraph (d) applies to the Cocopah Landfill, a Municipal Solid Waste landfill operated by Republic on the Cocopah Indian Reservation near Somerton, Arizona.(1) In accordance with § 258.60(b) , the owner or operator may replace the prescriptive final cover set forth in § 258.60(a) , with an alternative final cover as follows:(i) The owner or operator may install an evapotranspiration cover system as an alternative final cover for the 135-acre site.(ii) The alternative final cover system shall be constructed to achieve an equivalent reduction in infiltration as the infiltration layer specified in § 258.60(a)(1) and (2) and provide an equivalent protection from wind and water erosion as the erosion layer specified in § 258.60(a)(3) . Top-deck cover slopes shall have a minimum slope of 2%. All side slopes in the South Fill Area shall be regraded to a maximum 3 horizontal to 1 vertical (3H:1V). The existing side slope of 2.5H:1V in the North Fill Area will remain; however, drainage benches shall be installed on portions of the slope where the vertical height exceeds 50 feet.(iii) The final cover system shall consist of a minimum three-feet-thick multi-layer cover system comprised, from bottom to top, of: (A) A minimum 30-inch thick infiltration layer consisting of:(1) Existing intermediate cover; and(2) Additional cover soil from on-site sources, which, prior to placement, shall be wetted to optimal moisture and thoroughly mixed to near uniform condition, and the material shall then be placed in lifts with an uncompacted thickness of six to eight inches, spread evenly and compacted to 90 percent of the maximum dry density, and shall:(i) Exhibit a grain size distribution that excludes particles in excess of three inches in diameter;(ii) Have a minimum fines content (percent by weight passing U.S. No. 200 Sieve) of 12 percent for the average of ten consecutive tests; and(iii) Have a grain size distribution with a minimum of six percent finer than five microns for the average of ten consecutive tests; and(B) A surface erosion layer comprised of a rock/soil admixture for top deck slopes and rock armoring for side slopes. The surface erosion layer requirements for top-deck slopes and side slopes are detailed below:(1) Top deck slope surface erosion layer requirements: The top deck slope surface erosion layer shall be a minimum six-inch surface erosion layer comprised of a rock/soil admixture. The top deck surface erosion layer shall achieve the following gradation specification:(i) Exclude particles in excess of three inches in diameter;(ii) 40% to 75% passing No. 4 sieve(iii) 10% to 50% passing No. 40 sieve(iv) Less than or equal to 15% passing No. 200 sieve(2) Side slope surface erosion layer: The side slope surfaces erosion layer shall consist of a 4-inch thick rock armor underlain by an 8 ounce per square yard (oz/sy) non-woven geotextile filter fabric. The side slope surface erosion rock armor layer shall achieve the following gradation specification:(i) Exclude particles in excess of three inches in diameter;(ii) 10% to 40% passing No. 4 sieve(iii) 0% to 10% passing No. 40 sieve(2) In accordance with 40 CFR 258.29(a) , the owner operator may retain all required documentation relating to the operating record of the Cocopah Landfill at the administrative offices of Copper Mountain Landfill. The address of Copper Mountain Landfill is 34853 East County 12th Street, Wellton, Arizona 85356.(3) The owner or operator shall place documentation demonstrating compliance with the provisions of this Section in the operating record.(4) All other applicable provisions of 40 CFR part 258 remain in effect.75 FR 50932, Aug. 18, 2010, as amended at 81 FR 69409, Oct. 6, 2016; 82 FR 25535, June 2, 2017; 85 FR 53178, Aug. 28, 2020 As amended at 81 FR 69409, 10/6/2016; 82 FR 25535, 8/1/2017; 85 FR 53178, 8/28/2020