ARCHIVED REPORTS_1999 - Laserfiche WebLink

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GeoSyntec Consultants work will be performed by Forward prior to final waste acceptance. The foundation layer will be compacted to a minimum relative compaction of 90% (ASTM D1557). On-site sandy lean clays will be used to construct the compacted clay liner. These clays were used to construct the compacted clay liners within the base liners of WMU's D-87, D-88, D-89 and the Eastern Ash Pit. Hydraulic conductivity values from field testing for the Eastern Ash Pit typically ranged from 1 x 10-6 to 1 x 10-7 cm/s when tested with air entry permeameters. These field tests are in the appendix to this CQA Plan. The clay liner will be compacted to a minimum relative compaction of 90% (ASTM D1557), at a water content that will result in a hydraulic conductivity of 1 x 10-6 cm/s or less. If the on-site clays do not meet the hydraulic conductivity requirement of 1x106 cm/s or less, an offsite clay (NARCO clay from Ione, CA) can be imported and admixed with the on-site sandy lean clays for construction of the compacted clay liner. This type of admixed clay liner has been used successfully in the construction of the base liners for WMUs D-93, D-95, D-97, D-98, and D-99. A clay liner material evaluation program was conducted in 1993 for the construction of the compacted clay liner within D-93. When the on-site sandy clays were admixed with 25% MARCO clay, and compacted to a minimum relative compaction of 90% at a water content of 2 to 5% above optimum (ASTM D1557), a field hydraulic conductivity of 5 x 10-8 cm/s was measured with a large-scale, sealed double ring infiltrometer (SDRI) installed through a soil test pad. A copy of the clay liner material evaluation report for the admixed clay liner, including the SDRI test result, is included in the appendix to this CQA Plan. The vegetative layer will be constructed with on-site silty and clayey sands (SM) or (SC). The soils shall be placed at a minimum relative compaction of 85% (ASTM D1557). A minimum 2 -inch thick organic layer of shredded green waste or straw/hay will be placed over the vegetative layer after placing the grass seed mix. This organic layer will help retain moisture for seed germination as well as minimize raindrop impact and associated erosion. Forward has successfully used the following seed mix, from JDM Landscaping in Lodi, California, for erosion control at the site: 50% Annual Ryegrass 15% Gosse Subterranean Clover, Pel-Koted C J:WLLIED\FORWARD\CLOSURE\REPORT\CQA REPORT 2-2 99.11.30 9