SITE INFORMATION AND CORRESPONDENCE

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SU TE or CALIFORNIA GEORGE DEUKMEJIAN,Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD- CENTRAL VALLEY REGION 3201 S STREET r SACRAMENTO,CALIFORNIA 95816-7090 7 // PHONE: (916)445-0270 V 14 February 1985 ( � l ^ N q�Typ7/V t0C, R/6 Mr. G. Fred McCaig Georgia-Pacific Corporation 133 Peachtree Street, N.E. . Atlanta, Georgia 30303 GEORGIA-PACIFIC (G.P. ) STORMWATER POND CONTAMINATION - INVESTIGATION, CITY OF TRACY, SAN JOAQUIN COUNTY We have been requested to determine cleanup levels for the contaminants associated with the stormwater pond at G.P. Is Tracy facility. In order to determine final cleanup levels, a complete understanding of the horizontal and vertical extent of the plume, as well as detailed soils and geohydrologic information are needed. G.P. has been ordered by the Cleanup and Abatement order dated 25 September 1985 to provide this information. To date, the information received by this office allows only partial definitions of the plume, and a rough estimate of soils and geohydrologic conditions. Current information shows that contaminants are present in the soils exposed by the removal of the sludges, and in the ground water, which is less than 15 feet below the pond bottom. Contamination has also been found in a deeper zone, approximately 35 feet below the pond bottom. The shallow ground water is used as a potable source in the area. Until the required additional information is received by this office, cleanup levels must be set conservatively. In setting these levels, consideration is given to environmental attenuation, bioavailability, and cumulative toxicity of all chemicals associated with the stormwater pond. At present, chloroform and closely related chemicals are of concern. Other chemicals will be considered if they are detected. Since there seems to be very little, if any, barrier between contaminated soils and the ground water, there will be no consideration for environmental attenuation in determining the cleanup level. We will assume, however, that roughly 10% of the concentrations in the soil are available to migrate toward ground water. Based upon the above information, the cleanup levels are as follows: