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California 1JOKional Water Quality Cont Board <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Linda S.Adams Arnold <br /> Secretaryfor Sacramento Main Office Schwarzenegger <br /> Environmental 11020 Sun Center Drive#200,Rancho Cordova,Califomia 95670-6114 Governor <br /> Protection Phone(916)464-3291 -FAX(916)4644645 <br /> http://www.waterboards.ca.gov/centralvalley <br /> 8 September 2006 - ' _ 1i <br /> Mr. Kevin Basso, General Manager <br /> Forward Inc. <br /> 1145 West Charger Way <br /> Px ,1rf <br /> Stockton, CA 95206 � ���� <br /> REVIEW OF 2006 ANNUAL CORRECTIVE ACTION EVALUATION REPORT, AUSTIN <br /> ROA® LANDFILL, SAN JOAQUIN COUNTY <br /> Regional Water Quality Control Board staff has reviewed the 2006 Annual Corrective Action <br /> Evaluation Report, Austin Road Landfill(report) and has the following comments: <br /> 1. The report demonstrates that the corrective actions implemented at the former Austin <br /> Road Landfill are successfully remediating groundwater contamination just north of the <br /> landfill. However, the plume definitions in Figures E-1 through E-4 are somewhat <br /> misleading because they do not incorporate data from wells 8106A and 7898. These <br /> wells plus several monitoring wells north the infiltration gallery have shown no major <br /> reduction in VOCs or have shown an increase. <br /> 2. In future reports, isoconcentration maps should include data from wells 8106A and <br /> 7898, and should show several different isoconcentration contours (We recommend 1, <br /> 5, 10 and 15 ug/I contours). Staff understands that wells 8106A and 7898 are domestic <br /> wells and were not designed as monitoring wells. However, VOC concentrations from <br /> domestic wells are commonly more dilute than monitoring wells and thereby, the <br /> concentration in the aquifer are likely higher. Also, where these wells are located <br /> demonstrates the plume is a lot larger than shown by the monitoring wells. <br /> 3. Both monitoring wells AMW-13 and AMW-14 show upward VOC trends. Total VOCs in <br /> AMW-13 exceeded tolerance limits in the Third Quarter of 2005 and the First Quarter of <br /> 2006. The very high Third Quarter 2006 concentration is not consistent with rest of the <br /> well data and is likely an outlier that does not represent the true groundwater <br /> concentration. However, the First Quarter 2006 data appears to be valid and is <br /> consistent with a general upward trend in VOC concentrations in this well. Total VOC <br /> concentrations in AMW-14 also show a much less define upward trend over the <br /> previous five quarters. These two wells are north of and thus not controlled by the <br /> infiltration basin. <br /> 4. Staff remains concerned that chlorinated solvent contamination north of the recharge <br /> basin is not being remediate by the existing corrective actions. TCE and/or PCE <br /> concentrations in wells AMW-13, -14, 8106A and 7898 are above MCLs (5 ppb) and <br /> seem to be increasing. <br /> California Environmental Protection Agency <br /> ��Recycled Paper <br />