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Mr. Timm Corner <br />Manager, Environmental Resources <br />Proposed SLF Specification Changes <br />July 12, 2010 <br />amecr <br />The current Technical Specifications require in -situ testing of the SLF permeability, one test for <br />every 5,000 cubic yards (Table 2, Section 1400.1). In the implementation of this specification, <br />SLF is placed and compacted, tested for density and thickness, then a sample is take for <br />permeability testing. Until the SLF permeability can be tested and verified, the area cannot be <br />covered with geomembrane and is exposed to the environment. The time required to complete <br />the permeability test varies between 1 to 2 weeks (AMEC does the testing on -site to minimize <br />the required testing time). During this period of time, the SLF is exposed to several drying and <br />wetting cycles and, in the monsoon season, heavy downpours. These conditions can damage <br />the SLF, requiring reworking and moisture conditioning, and in some cases complete <br />replacement. While reworking the SLF is done at CC &V, the quality of the re- worked SLF (even <br />though it meets the specifications), is not as good as fresh SLF. <br />In order to preserve the high quality of fresh SLF, AMEC proposes changing the requirement for <br />in -situ permeability testing of the SLF to testing the SLF stockpiles (density and thickness <br />testing would still be done in -situ since these tests take very time). Testing of the stockpiles will <br />allow the SLF permeability to be checked prior to placement. Once the SLF is placed and <br />compacted (density and thickness tests completed and passed), it can be covered by <br />geomembrane liner. This will preserve the quality of the SLF and prevent damage that can <br />occur after placement. <br />AMEC believes these proposed changes to the SLF specification will not affect the performance <br />or solution containment of the VLF. <br />If you have any questions or comments, please contact me at (303) 433 -0262. <br />Sincerely, <br />AMEC Earth & Environmental, Inc. <br />John F. Lupo, Ph.D., P.E. <br />Principal Engineer <br />S: \PROJECTS \1125E CCV CQA \e - correspondence \slf spec letter.doc <br />2 <br />