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Californi egional Water Quality Co. of Board <br /> Central Valley Region <br /> $1, Robert Schneider,Chair °"'�'`� <br /> Linda S.Adams Arnold <br /> Secretary for 6 J�,. Sacramento Main Office Schwarzenegger <br /> ^Q� 11020 Sun Center Drive#200,Rancho Cordova,Calibmia 95670-6114 <br /> Environmental 1 Governor <br /> Protection �('l'' =; t ' ; ;k� Phone(916)464-3291 •FAX(916)464-4645 <br /> j�t,n 11_1'py�,P- r01 ` http://www.waterboards.ca.gov/centralvalley <br /> �� <br /> 6 July 2006 \AE c <br /> Mr. Scott Hilyard <br /> California Army National Guard <br /> 10620 Mather Blvd. <br /> Sacramento, CA 95655 <br /> DRAFT FIELD SAMPLING PLAN, STOCKTON FMS#24 UST SITE, CALIFORNIA ARMY <br /> NATIONAL GUARD FACILITY, 8010 AIRPORT WAYAND 2000 STIMPSON ROAD STOCKTON, <br /> SAN JOA QVIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region(Regional Water Board) staff <br /> has reviewed the Draft Field Sampling Plan, Stockton FMS#24 Site (Draft Plan) for the California <br /> Army National Guard (LANG) Facility dated 23 March 2006. Regional Water Board staff comments on <br /> the Draft Plan are provided below. <br /> General Comments <br /> 1. With a few exceptions, the Draft Plan is detailed and well organized. The Draft Plan is a <br /> significant improvement over previous work plans and reports submitted by CANG for Regional <br /> Water Board staff review. <br /> 2. Section 3.2.3 of the Draft Plan indicates the vertical extent of groundwater contamination has not <br /> been determined, but the proposed sampling program does not include collection of groundwater <br /> samples below the top of the water table (approx. 40 to 45 feet below ground surface). Add <br /> collection of deeper groundwater samples to the Final Plan. <br /> 3. The Draft Plan does not propose installation of any groundwater monitoring wells. <br /> Concentrations of benzene,toluene, ethylbenzene, and xylenes (BTEX); total petroleum <br /> hydrocarbons as gasoline (TPHg); and total petroleum hydrocarbons as diesel (TPHd) detected in <br /> 2004 groundwater"grab" samples were well above applicable water quality objectives. <br /> Installation of permanent groundwater monitoring well(s) is warranted based on the 2004 <br /> investigation findings. Revise the Draft Plan to include installation of monitoring well(s) after <br /> the groundwater"grab" sample results are obtained from the five borings. The sample results <br /> should be used to optimize placement of the monitoring well(s). The Final Plan should state that <br /> the new well(s)will be sampled quarterly for TPH and BTEX for the first year. <br /> 4. The Draft Plan concludes that potential exposure of workers to site contaminants via inhalation, <br /> dermal, and ingestion pathways is low. It is premature to draw this conclusion because the extent <br /> of soil and groundwater contamination has not been defined yet and concentrations of benzene <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />