Laserfiche WebLink
i *­ MEMORANDUM .- <br /> CPLIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION <br /> 3443 Rougier Road Phone: (916) 361-5600 <br /> Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 <br /> TO: Antonia K. J. Vorster FROM: Robert A. Evans <br /> Senior Engineer Area Engineer <br /> DATE: 30 October 1989 SIGNATURE: l <br /> SUBJECT: GROUND WATER MONITORING PLAN, ALL PURE CHEMICAL, TRACY, SAN JOAQUIN COUNTY <br /> I have reviewed the Technical Report & Asscssme^t of Soil and Ground Water Contamination <br /> dated 26 July 1989 and the Subchapter 15 Ground Water Monitoring Program Workplan dated <br /> 14 July 1989, submitted by the Traverse Group, Inc. (TGI) on behalf of All Pure Chemical <br /> (APC) in Tracy, CA. The objective of this Workplan is to determine 1) to what extent <br /> the shallow ground water has been impacted by APC's discharge to its wastewater ponds; <br /> 2) the local ground water flow direction; 3) the stratigraphy and hydrology at the site. <br /> The Assessment indicated that significant fuel and non-fuel hydrocarbon contamination <br /> is present in the shallow ground water just southeast of the wastewater ponds along the <br /> property line; however, this Workplan is focusing only on determining the impacts of <br /> APC's discharge on ground water. APC states that the fuel hydrocarbon sources are <br /> offsite. <br /> TECHNICAL REPORT & ASSESSMENT <br /> In July 1988, AGRO Environmental Services found 8260 mg/l of high boiling point <br /> hydrocarbons (HBPH) in a water sample taken 10.6 feet below grade from borehole on the <br /> east side of APL's property. Subsequently, APC retained Traverse to determine the <br /> source and areal extent of the hydrocarbon contamination. The results of the Traverse <br /> investigation were as follows: <br /> 1 . The water table is approximately 13 feet below grade. <br /> 2. No hvdrocarbon cor.tam;natio;� was found in the two onsite production water <br /> supply wells; however, no well logs are available to determine water bearing <br /> zones or well screen locations. Estimated well depths are 60 and 150 feet. <br /> 3. Petroleum product was found in boreholes TB4, TBS, TB6, and TB7. Petroleum <br /> products conveyed through the pipeline systems adjacent to All Pure property <br /> are similar to the product recovered in borehole TB5. <br /> 4. High concentrations of high boiling point hydrocarbons and purgeable <br /> hydrocarbons were found in both the soil and ground water near the <br /> southeastern corner of the property. HBPHs were found in high concentrations <br /> in boreholes, TB5 and TB7. Purgeable hydrocarbons were found in high <br /> concentrations in boreholes TB5 and TB7 and above detection limits in <br /> boreholes TB4, TB6, and TB8. <br /> 5. Chloroform was found in water and soil samples from boreholes TB4, TB8, TB9, <br /> while other volatile organics were found in lower concentrations in boreholes <br /> TB9 and TB10. <br />