SITE INFORMATION AND CORRESPONDENCE_FILE 1

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i � y PUBLIC HEALTH SERVICES SAN JOAQUIN COUNTY = .z JOGI KHANNA M.D.,M.P.H. Health Officer P • • P.O. Box 2009 (1601 East Hazelton Avenue) Stockton,California 95201 (209)468-3400 MAY 17 1991 D � WILLIAM HEMPHILL ROYAL OAKS SAVINGS AND LOAN P 0 BOX 1007 MANTECA CA 95336 RE: Royal Oaks Savings &Loan IN REPLY REFER TO SITE CODE: 2393 510 N. Main Manteca, CA We have reviewed the "Letter Report" dated March 29, 1991, submitted by Henkle and Associates. They have proposed that further action at this site be "monitoring only." Based on the analytical results from the groundwater samples collected on February 11, 1991 and March 12, 1991, we agree that the monitoring wells should continue to be sampled on a quarterly basis and groundwater level measurements taken to confirm the groundwater gradient at the site. Monitoring well #2 is located upgradient of the former tank location and the water sample results from March 12, 1991 showed contamination. In your Final Remediation Plan dated October 24, 1990,you stated that low level soil contamination was left in place near monitoring well#2. In your next report to this office calculate the quantity of contaminated soil left in this area of the site. We are aware that a domestic well is located at 581 through 585 Grant Street, Manteca. Our records indicate that there is also a well at 545 Grant Street,Manteca. These wells are downgradient from your site. As noted in your reports, the soil at this site is sandy. Pollutants are known to migrate rapidly through this permeable soil type. In December, 1990,pump tests were conducted and from your statement in the Final Remediation Plan Addendum #II dated January 24, 1991, it appears over 10,000 gallons of groundwater were extracted. This action might have removed localized contaminants in the groundwater but there is still the possibility that some contaminants migrated off-site. Therefore, the above two domestic wells should be sampled for total petroleum hydrocarbons as gasoline, benzene, toluene, ethyl benzene, and xylene. Authorization from the owner of these wells must be obtained prior to sampling them. This office is to be notified 48 hours prior to the sampling so that we can be present for observation. We received a letter from Robert Isackson, Village Properties, dated April 3, 1991, requesting information on"the amount of future monitoring required"and the levels to be achieved"to obtain groundwater closure." While we can appreciate your need to appropriate the correct dollar amount for future remedial work, it is not possible for us to make these judgements. There are no cleanup levels or specified time periods for monitoring established. These decisions are made on the information gathered during the site investigation. We will consider a request for closure of this site after a year of quarterly sampling indicates no detection of contaminants in any of the monitoring wells. Water samples must be analyzed by an appropriately certified lab utilizing methods and detection limits listed in the Tri-Regional Recommendations and the LUFT Manual. A Division of San Joaquin County Health Care Services