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23/16/2001 11:33 20646710 AGE STOCKTON • PAGE 20 <br /> California Regional Water Quality Control Board <br /> Central Valley Region , <br /> Winston H.M&oz <br /> )Robert Schneider,Chair Gray Davis <br /> Saoararyfor Sacramento Mata Office Governor <br /> Eaw,o ^ental lntenta Address: http:/A w .awrcb.ca.gov/—rwgcb5 <br /> Prorecvan 3443 Rouder Road.Suite A,Sacramento,Califomia 9SS27-3003 <br /> Phone(916)255-3000•PAX(916)255-3015 . <br /> 2 March 2001 <br /> Mr. Jeffrey Wong RECEIVED <br /> Senior Registered Environmental Health Specialist MAR 0 Q 1001 <br /> San Joaquin County Environmental Health Division <br /> 304 East Weber Avenue <br /> Stockton, CA 95202 <br /> REQUIREMENT FOR INTERIM REMEDIATION,RAINWATER CAR WASH <br /> 420 WEST YOSEMITEAVENUE,MANTECA, SAY JOA QUEV COUNTY <br /> During our 28 February 2001 meeting,we discussed the Cone Penetrometer Testing Site Investigation, <br /> Fourth Quarter 2000 and the January 2001 draft sampling results for monitoring wells MW-1 through <br /> MW-4,both submitted by Advanced GeoEnvironmental (AGE). Groundwater samples collected from <br /> on-site monitoring wells in January 2001 contained up to 120,000 µgQ TPHg; 9,900 µg/1 benzene; and <br /> 730,000 µg/1 MtBE. The current depth to water in the ou-site monitoring wells is about 17 feet bgs, and <br /> the reported groundwater flow is north/northeast. Results of the depth-discrete groundwater samples <br /> collected from the cone penetrometer testing(CPT)borings at 130 feet show MtBE at 39 µg/l. <br /> Tetrachloroethylene and trichloroethylene also were identified in the groundwater samples at maximum <br /> concentrations of 1,600 µg/1 and 28 pg/l, respectively. At this time, it is uncertain where the source of <br /> these solvents originated, and we are greatly concerned that the aquifer;which is used for domestic And <br /> municipal water supply,has been impacted. <br /> As presented in AGE's 8 September 2000 Sensitive Receptor Survey, two municipal water supply wells <br /> are within 2,000 feet of Rainwater Car Wash. One well (Almond Street Well) is about 1,900 feet <br /> northwest of the site and reportedly is non-operational. The other well (Jessie Street Well), which is <br /> operational,is about 1,500 feet south of the site. This well is cased to 100 feet and"open-hole"from <br /> 100.to 325 feet: The reported pumping rate for this well,is 1,100 gallons per minute. <br /> AGE recommended in the CPT Site Investigation to install an interim remediation system to reduce <br /> off-site migration of the groundwater plume. The system is appropriate to reduce contaminant mass and <br /> control the lateral and vertical movement of contaminated groundwater until the completion of the site <br /> assessment. Therefore,require Rainwater Car Wash to complete the following: <br /> • By 16 April 2001, install and continuously operate an interim pump and treat system in the area <br /> of the highest on-site groundwater contamination. The system should remove product and <br /> stabilize the groundwater plume- <br /> California Environmental Protection Agency <br /> Co Recycled/vdper <br /> The energy challenge Pacing California is real. Every Californian needs to take immediam melon to reduce energy consumption. For a list of simple ways <br /> you can reduce demand and cut your energy coats,see our Web-site M http://www.3wrcb,ca.govhwgebff <br />