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Andrew Keller - 2 - 17 January 2007 <br />Staff Comments: <br />2. <br />a. Revised footprint. Staff concurs with the revised footprint, provided the modified <br />cap footprint retains full coverage of the former landfill and auto shredder waste. <br />b. Perimeter slope. By 28 February 2007, the Discharger shall provide detailed <br />topographic drawings of the final cap and perimeter slopes design for discussion <br />of the slope -stability analysis with the Regional Water Board staff. <br />Hydraulic Conductivity Testing <br />Discharger Proposal: <br />a. Reduction in Quantity of Double Ring Infiltrometer Tests (DRI). The Discharger <br />requested a reduction in the quantity of DRI tests (ASTM D 3385) from four tests <br />to one test. Using one DRI, the test time would be reduced to approximately two <br />to three weeks. The request for a reduction was based on the assumption that <br />the four tests would extend the cap finish date to beyond the scheduled finish <br />date. <br />b. Hydraulic Conductivity (ASTM D 5084) and BAT® Field Screen Tests. <br />At the DRI test pad, the Discharger proposed to supplement the single DRI with <br />four laboratory -performed measurements of hydraulic conductivity via ASTM D <br />5084 and four BAT field -screening tests. In addition, ASTMD D 5084 would be <br />performed at the rate of one test for each 1,000 -cubic yards of compacted soil. <br />The Discharger proposed that if the laboratory -performed ASTM D 5084 failed <br />the passing criteria (1x10-6 centimeters/second [cm/sec]), then the laboratory test <br />results would be disregarded in favor of a passing BAT field test result (i.e., 1x10- <br />6 cm/sec or slower). In addition, the Discharger stated that if the BAT field test <br />failed it's passing criteria of 1x10-6 cm/sec, then that portion of the compacted <br />material would be removed, recompacted, and retested. <br />Staff Comments: <br />a. DRI tests. Staff concurs with the proposed reduction to one DRI test pad, via <br />ASTM D 3385. <br />b. Hydraulic Conductivity (ASTM D 5084) and BAT Field Screen. <br />i. Staff concurs with the proposed addition of four ASTM D 5084 (Hydraulic <br />Conductivity) and BAT tests at the DRI test pad. <br />ii. Staff concurs with the implementation of ASTM D 5084 at the rate of one <br />test for each 1,000 -cubic yards of compacted soil for the entire cap. <br />iii. Staff does not concur with the Discharger's proposal to discard/disregard <br />failing ASTM D 5084 test results in favor of passing test results using the <br />BAT field screen test. By February 28, 2007, the Discharger shall provide <br />(1) field procedures for pass/fail criteria of ASTM D 5084 hydraulic <br />conductivity requirements, (2) pass/fail criteria for failing BAT tests, (3) <br />frequency of BAT testing, and (4) subsequent removal and re -compacting <br />procedures where ASTM D 5084 or BAT test results do not meet passing <br />criteria. <br />Staffs position is based on a review of ASTM D 5084 and the BAT manual: neither <br />provides data or text that suggests that the BAT test results are more accurate or <br />