ARCHIVED REPORTS_2006 - Laserfiche WebLink

Home Browse Search

• THO �.PLENN P.O.BOX 1910-1910 S,HAZIELTON AYIENUE ' DIRECTOR STOCKTON,CAUPORNIA 9=1 (209)468-3000 FAX(209)468-2990 wovw.Sig-o g THOMAS hL GAUI DEPUTY DIRECTOR MANU EL SOLORIO WaddagYOU DEPUTY DIRECTOR STEVIBN WINKLEER DEPUTY DIRECTOR ROUR JANIE$ BUSINESS ADMINISTRATOR July 31, 2006 Mr. Todd Del Frate California Regional Water Quality Control Board 11020 Sun Center Drive, 4200 Rancho Cordova, California 95670-6114 SUBJECT: SECOND QUARTER 2006 GROUNDWATER MONITORING REPORT, CORRAL HOLLOW SANITARY LANDFILL Dear Mr. Del Frate: Enclosed is the Second Quarter Groundwater and Surface Water Monitoring Report for the Corral Hollow Sanitary Landfill, due July 31, 2006. Concentrations of parameters in all groundwater wells were within established concentration limits. At MW-4, the overall increasing trend in Nitrate and the decreasing trend in pH continue. However, data from the last five quarters indicate a possible reversal of these trends. As noted in our letter accompanying last year's final report, we suspect that previous trends were caused by rainwater percolating through refuse that apparently extends beyond the landfill closure cap and below the drainage ditch adjacent to the eastern landfill road where well MW-4 is located. We improved the drainage of this ditch in late 2003, which apparently reduced or eliminated infiltration of rain water into the landfill there (see our April 4, 2006 letter and report,Results of Exploration to Assess Source of Groundwater Impact at the Closed Corral Hollow Landfill). This summer we intend to determine the extent of the closure cap, and to extend it as needed to cover all refuse. Seven VOCs were reported in impacted well MW-5, four of which in "trace" concentration. No VOCs were reported in the other two shallow aquifer wells. No VOCs were reported in any of the deep aquifer wells. Concentrations do not exceed 10 parts per billion.