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7 + <br /> Mr. Boardman , __- -2_ March 1, 2 <br /> Page 3-4,Section 3.4.2.1-"Final Cover�G�rading!_ - - = - <br /> ➢ Provide the design for this temporary drainage control system and include it in the Plan. <br /> Page 3-5.Section 3.4.2.2-"Final Cover-rMateriar- <br /> ➢ Has there been any test performed on this:on-site-soil-to,deterrnine-its adequacy=to-be-utilized�sfnaL-.= - <br /> cover? <br /> Page 3-6,Section 3.4.2.2-"Final Cover material" <br /> ➢ The cost associated with this off-site clay must be included in the cost estimates. _- <br /> Page 3-14,Section 3.4.5-"Landfill Gas Control" <br /> ➢ Provide the frequency of this gas monitoring survey(i.e.,monthly,quarterly,etc.) <br /> Page 5-2,Table 5-1-"Estimated Partial Final Closure" <br /> ➢ Please include the actual cost of the first four(4) items on this table. <br /> Appendix C-Page 2-1.Section 2-"Project Description" <br /> ➢ Please note that the existing cover must be compacted to a relative compaction of 90%in accordance <br /> with ASTM D1557. <br /> Appendix C-Page 7-4.Section 7.6-"Final CQA Report" <br /> ➢ The Board should also be provided with a copy of the Final CQA Report. <br /> Landfill Gas Monitoring <br /> ➢ In the SCS Engineers letter dated September 2, 1999, it is stated that there are ten landfill gas <br /> monitoring probes installed around the site extending to a depth of 3 feet below grade. In regard to <br /> this we have the following comments and concern: <br /> I. Were these probes installed in accordance with 27 CCR, §20925? <br /> 11. Include the as-built description, including a well detail which indicates probe material and depth, <br /> extent and type of filter pack, thickness and material used for seals,extent and material used for <br /> backfill, and size and interval of perforations. <br /> III. Include the latest four quarterly gas monitoring results in the Plan. <br /> ➢ In a letter dated September 2, 1999, included in the Plan, SCS Engineers have concluded that the <br /> installation of a gas collection and control system is not required at the time of closure for WNW B <br /> under New Source Performance Standard(HSPS). We like to point out that the site may be exempt <br /> under NSPS to install a gas control system, however, it does not relieve the operator to comply with 27 <br /> CCR, §§20919 and 20937 to install a gas collection system. <br /> ➢ Landfill gas probes should be pressure tested at least annually to ensure they are functioning properly. <br /> This should be included in annual maintenance activities and costs. <br />