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Office of Environmental Health Hazard Assessment
<br /> Joan Denton, Direor
<br /> \ Headquarters•301 Capitol Mall,R .205•Sac ct
<br /> ramento,California 958144327•www.calepa.cahwnet.gov/oehha
<br /> Berkeley Office•Mailing Address: 2151 Berkeley Way,Annex 11,•Berkeley,California 94704
<br /> a;
<br /> Peter M.Rooney MEMORANDUM °
<br /> Secretaryfor •
<br /> Envoonmental Pete Wilson
<br /> Protection Governor
<br /> TO: David Stavarek, R.G.
<br /> California Regional Water Quality Control Board
<br /> Central Valley Region
<br /> 3443 Routier Road, Suite A
<br /> Sacramento, CA 95827-3098
<br /> VIA: David M. Siegel, Ph.D., Chief
<br /> Hazardous Waste Toxicology Section
<br /> FROM: Julio A. Salinas, Ph.D., Biochem.D.
<br /> Hazardous Waste Toxicology Secticd
<br /> DATE: June 29, 1998
<br /> SUBJECT: REVIEW OF RISK ASSESSMENT WORKPLAN FOR THE FORMER
<br /> PUROGROBREA FACILITY, STOCKTON
<br /> I have reviewed the document entitled"Risk Assessment Workplan -Former PuroGroBrea
<br /> Facility, 1905 North Broadway Avenue, Stockton, California," (hereinafter the Workplan). The
<br /> document was prepared by Sierra-Pacific Groundwater Consultants, Inc. ("Sierra Pacific'), El
<br /> Dorado Hills, CA, Project No. 94-055.08, dated March 26, 1998.
<br /> Background
<br /> The Former PuroGroBrea Facility is located in east Stockton, in an area zoned for industrial and
<br /> residential use. The six-acre facility has functioned as an agrichemical facility under various ownerships
<br /> since the 1950s. In 1987, 1,2-dichloropropane (1,2-DCP) was detected in two nearby California Water
<br /> Services wells. Analytical data collected since 1993 have indicated presence of nitrates and pesticides
<br /> in both the on-site and off-site shallow groundwater. Soil and groundwater contaminants are believed to
<br /> have originated from two shallow evaporation ponds that existed at the site between 1965 and 1985.
<br /> Between 1981 and 1993, the following contaminants were identified in soil at various concentrations:
<br /> ethion, endosulfan, DDE, DDD, DDT,DBCP, diuron, lindane, linuron, endrin aldehyde, 1,2-DCP, 1,2,3-
<br /> TCP, TPH, nitrate,nitrite, heptachlor, endrin, and gamma-chlordane. Groundwater from four
<br /> monitoring wells constructed in 1993 showed presence of 1,2,3-TCP. In 1994 and 1995, soil and
<br /> groundwater were analyzed, but results are not reported, except that`various chemicals and nitrogen
<br /> compounds were detected." In 1996, a new monitoring well was installed on-site and groundwater
<br /> analysis has continued. In 1997 additional soil borings were sampled and analyzed.
<br /> California Environmental Protection Agency _
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