CORRESPONDENCE_2008 (1/08 TO 6/08)

Home Browse Search

pOU1ry 1�Q'." .: .90G 0: �9 �P �%PORN THOMAS M. GAU DEPUTY DIRECTOR MANUEL SOLORIO DEPUTY DIRECTOR STEVEN WINKLER DEPUTY DIRECTOR ROGERJANES BUSINESS ADMINISTRATOR THOMAS R. FLINN DIRECTOR I I I- Worlcmg YOU 0"PIUMORM Mr. Todd Del Frate California Regional Water Quality Control Board 11020 Sun Center Drive, #200 Rancho Cordova, California 95670-6114 P. O. BOX 1810 - 1810 E. HAZELTON AVENUE STOCKTON, CALIFORNIA 95201 (209) 468-3000 FAX (209) 468-2999 www.sjgov.org MAY A2,0�1,,,%rrsv r SUBJECT: FIRST QUARTER 2008 GROUNDWATER MONITORING REPORT, CORRAL HOLLOW SANITARY LANDFILL Dear Mr. Del Frate: Enclosed please find the First Quarter 2008 Groundwater and Surface Water Monitoring Report for the Corral Hollow Sanitary Landfill. Monitoring was performed in accordance with the monitoring program included with the Waste Discharge Requirements (WDRs) approved by the Regional Water Quality Control Board for this site. Concentrations of parameters in all wells were within established concentration limits. Groundwater conditions at the landfill are similar to last quarter. Seven VOCs were reported in well MW -5 (the impacted well), none above 7 ppb, two of which were at "trace" concentration. No VOCs were reported at shallow aquifer wells SB -1 or MW -4, or at any deep aquifer well. TO -14 analyses of soil gas are included, along with concentrations of major gasses (02, CO2, CH4, and N2) per your request. Progress of Corrective Action Measures is submitted during the first and third quarters, and is therefore included in this quarterly report. Monitoring data indicates significant improvement in groundwater quality at well MW -5 (the impacted well) since operation of the LFG system in late 2001, although this improvement has stabilized in the recent years. We continue to see improvement in the inorganic parameters at MW -4 that we attribute to grading improvements in late 2003. This continuing improvement seems to indicate that the lack of closure cover over small portions of the refuse at the eastern edge of the landfill is not negatively impacting groundwater at this time. This was the first quarter in which MW -8 was monitored, and the results are quite interesting. Five VOCs were reported (four in the retest), none above 3 ppb. These VOCs are consistent with those found in MW -5, but are fewer in number and generally at lower concentrations. The direction of this concentration gradient supports the conclusion that the VOCs in both MW -5 and MW -8 emanate from the small area of refuse recently found south of MW -5, rather than from the landfill as a whole. This is a significant finding which allows us to focus on increasing LFG collection in that area.