Laserfiche WebLink
C. <br />Geologists, Hydrogeologists and Engineers <br />Mr. Curt Fujii, P.E. <br />c/o Keller Canyon Landfill <br />901 Bailey Road <br />Pittsburg, CA 94565 <br />LEACHATE FATE ANALYSES <br />PRESCRIPTIVE CLAY LINER <br />FORWARD LANDFILL. <br />February 11, 2002 <br />Revised February 20, 2002 <br />Revised May 30, 2002 <br />Revised September 19, 2002 <br />JN 02-002 <br />1.0 INTRODUCTION <br />This letter report identifies work completed by GeoLogic Associates (GLA) to evaluate <br />the suitability of the single, composite liner proposed for the Forward Landfill to meet the <br />waste containment requirements included in California Code of Regulations (CCR) Title <br />27. Specifically, this work was performed to assess the fate of common landfill <br />constituents in leachate at the Forward Landfill (potential groundwater contaminants) <br />during transport through leaks in the proposed single composite landfill liner wsithin the <br />approximately 127 -acre vertical and horizontal expansion area. For the Forward Landfill, <br />the proposed liner is consistent with 27 CCR minimum design standards, and <br />incorporates a 60 -mil HDPE geomembrane barrier over two feet of compacted clay <br />whose hydraulic conductivity is less than 1 x 10-7 centimeters per second (cm/s). <br />This report revises leachate fate analyses that were completed earlier for the project by <br />GLA (February and May 2002), and is intended to address comments made by the <br />Regional Water Quality Control Board (RCB; August 14, 2002) relative to these <br />earlier submittals. Data was presented in the earlier report submittals to support the <br />inference that VOCs would be largely biodegraded by microbes present within the <br />landfill and included in the carbon -rich landfill leachate. In the absence of peer-reviewed <br />studies of VOC attenuation within compacted clays, RWQCB staff requested additional <br />analyses to calculate the degree to which unattenuated leachate might impact <br />groundwater at the site. <br />As detailed herein, the new analyses specifically address leachate fate during unsaturated <br />flow through the vadose zone, and direct mixing of leachate with groundwater assuming <br />the historical average leachate chemistry at the facility. These analyses indicate that the <br />vadose zone beneath the landfill would act as an efficient buffer that would essentially <br />preclude leachate impacts to groundwater. <br />1831 Commercenter East, San Bernardino, CA 92408 Phone: (909) 383-8728 Fax: (909) 383-8732 <br />