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%W - <br />California Re�ional Water Quality Antrol Board <br />Winston H. Hickox <br />Secretaryfor <br />Environmental <br />Protection <br />13 March 2000 <br />Central Valley Region <br />Steven T. Butler, Chair <br />Sacramento Main Office <br />Internet Address: http://www.swrcb.ca.gov/--rwgcb5 <br />3443 Routier Road, Suite A, Sacramento, California 95827-3003 <br />Phone (916) 255-3000 •FAX (916) 255-3Wft E A I V ° <br />. (■` �r <br />Mr. Eric Jenks <br />John Taylor Fertilizers Company Inc. <br />841 West Elkhorn Blvd. <br />Rio Linda, CA 95673 <br />MAR 15 2000 <br />ENVIRONMENTAL HEALTH <br />PERMIT/ SERVICES . <br />Gray Davis <br />Governor <br />CONDITIONAL APPROVAL OF MONITORING WELL INSTALLATION WORKPLAN, REVIEW <br />OF SITE INVESTIGATION WORK REPORT, JOHN TAYLOR FERTILIZERS, STOCKTON, SAN <br />JOA QUIN COUNTY <br />I have received the 30 January 2000 Site Investigation Work Report (report) prepared by GeoSyntec <br />Consultants (GeoSyntec) that describes the results of the grab groundwater investigation at the John <br />Taylor Fertilizer (JTF) site in Stockton. The report also includes a work plan to install five shallow <br />monitoring wells. I review the report and work plan below. <br />Site Investigation Report <br />GeoSyntec reviewed historical files and discovered that JTF removed three underground fuel tanks in <br />1991 and installed a new tank in 1992. Geosyntec's groundwater investigation found MTBE at 1,000 <br />ppb in the center of the site (STO-A), and at 40 ppb southeast of STO-A. <br />Grab groundwater samples show nitrate concentrations greater than 90 mg/l north, east, and south of the <br />site center, and nitrate concentrations between non-detectable and 30 mg/l at the site center in an east - <br />west trending plume encompassing the Vapam tank, the fuel island, and Shop #1. These low <br />concentrations of nitrate, in the midst of greater concentrations, indicate that some degree of degradation <br />of nitrate may be occurring here. In the future, JTF may wish to include field tests of groundwater <br />samples for redox potential and dissolved oxygen content, and laboratory analyses for manganese and <br />iron constituents to determine whether denitrifying conditions exist in the groundwater. <br />The grab groundwater investigation also shows that nitrogen concentrations are greater than 100 mg/l in <br />the western area of the property where fertilizer products were not handled. The adjoining property to <br />the west is undeveloped land. If the groundwater gradient is eastward, as indicated by the MTBE <br />concentration gradient, this suggests that it will be important to carefully position an upgradient well to <br />determine what background concentrations are in this region. If background concentrations of nitrate are <br />greater than the water quality objectives, the background concentration will define the cleanup goal. The <br />same is true for background soil nitrate concentrations. <br />California Environmental Protection Agency <br />01 Recycles! Paper <br />