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STATE OF CALIFORNIA—ENVIRONMENTAL PRO'�AIhON AGENCY 1 <br /> _ ti X11 PETE WILSON,Governor <br /> ` s T' � <br /> CALIFORNIA REGIONAL WATER QUALITY CON,TR(J ;tB — ,v « , <br /> CENTRAL VALLEY REGION - <br /> 3443 ROUTIER ROAD,SUITE A <br /> SACRAMENTO,CA 95827-3098 L <br /> PHONE: (916)255-3000 OR <br /> FAX: (916)255-3015 <br /> 11 July 1996 <br /> Mr. Tom Welch <br /> Westrec Properties <br /> 116633 Ventura Blvd., 6th Floor <br /> Encino,CA 91436 <br /> REVIEW OF FIRST QUARTER 1996 GROUNDWATER MONITORING <br /> REPORT, TOWER PARK MARINA, 14900 W. HIGHWAY 12, LODI (SAN <br /> JOAQUIN COUNTY) <br /> Staff reviewed the First Quarter 1996 Groundwater Monitoring Report submitted on behalf of <br /> Tower Park Marina by SECOR International in accordance with Monitoring and Reporting <br /> Program(MRP) Order 95-802. <br /> The report shows that increases in hydrocarbon concentrations have been detected in several wells, <br /> and that compared to December 1995 readings, ground water levels have risen. Groundwater at <br /> the site continues to flow away from Potato Slough and to differ from the regional gradient. Free <br /> product has been reduced to a sheen in MW-3,but dissolved concentrations are reported at <br /> 16,000µg/L TPH-d and 320µg/L TPH-g. This is an increase from 4000µg/L TPH-d and ND <br /> TPH-g over December 1995 levels. Increased concentration of TPH-d in MW-2 and MW-4 also <br /> are reported. The increase in MW-2 was from ND in December 1995 to 90µg/L in March . <br /> MW-2 regularly varies from ND to low levels of diesel. A slight increase in xylene was reported <br /> in MW-4. Additionally, 1.4µ/L toluene was detected in MW-4 and 90µ/L TPH-d was reported <br /> from MW-5. These are the first detections of these compounds in these wells since June 1993. <br /> MW-5, a cross-gradient well, has had no detections of any hydrocarbons since 1993. <br /> We believe that these results indicate redissolving of residual hydrocarbons in the vadose <br /> zone as a result of the rising water table. The increases occurred even though dissolved oxygen <br /> levels increased in all the wells except MW-4,which may inndicate that significant biological <br /> activity is not occurring. <br /> Other issues: <br /> Field Protocols: As discussed via telephone with SECOR staff on 8 July, we had some <br /> concerns about the field procedures involving the wells containing ORC socks. Staff noticed that <br /> the field notes accompanying the report state that depth to water measurements were taken with the <br /> ORC socks in place in place in wells MW-2,-3,and -4. Since the socks are 2 inches in diameter <br /> and are arranged in a string of five placed in a 2-inch diameter well,with the top sock initially <br /> placed at the water surface,it is not clear how in-well measurements could be taken with reliable <br /> results. Staff assumed that the socks were removed after the initial depth to water measurements <br /> were taken, and before other procedures were performed. The telephone discussion confirmed <br /> this. Future reports should contain a summary of field protocols that specifies and clarifies actual <br />