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` r..� 2701 Cottage Way, Ste 25 <br /> Wm. I Hunter & Associates f •- Sacramento, CA 95825 <br /> n« r <br /> Registered Geologists , i <br /> (916) 972-7941 <br /> Petroleum & Mineral Appraisers %' <br /> APR 1.941 <br /> ENV/RONMCNT <br /> AL PERMIT/SERVICES HEALTH <br /> March 21, 1991 <br /> r <br /> Claudio Dell 'Eva <br /> 530 Yale Street `' 0 <br /> San Francisco, CA 94134 <br /> Ref: File review of Manteca Bean & Diamond Lumber projects, <br /> Manteca <br /> Dear Mr. Dell 'Eva; <br /> As a follow up to our telephone conversation, I will summarize <br /> the results of my file review at the EHD office yesterday, (March <br /> 20. ) I had last reviewed the Manteca Bean file in May, 1990, and <br /> had not been aware of the National Lumber problem at that time. <br /> During my review of the Manteca Bean file last year, I noted that <br /> 14 groundwater monitoring wells had been placed around the site <br /> of a known gasoline leak. Refer to my Site Assessment Report for <br /> details. One well , #14, is closest to, and downgradient from, <br /> the site of the UST that was removed from your property. <br /> Analysis of groundwater samples from that well taken on 11/14/89 <br /> showed 380 ppb TPH-G, and 0 ppb of BTEX. A sample taken from <br /> that well on 3/23/1990 did not reveal ANY detectable levels on <br /> contaminants. <br /> Groundwater Technology, (GTI , ) has submitted a Final Remediation <br /> Plan, (dated 9/17/1990, ) to remove hydrocarbon vapors from the <br /> soil by 'a vapor extraction technique, and clean up the water by a <br /> pump and treat system. This consists of pumping out contaminated <br /> water from a well near the center of the source, removing the <br /> contaminants, and then either disposing of the water into the <br /> sewer system or, assuming it is clean enough, returning it to the <br /> aquifer. Withdrawing water from the center of the plume will <br /> create a cone or pressure differential , drawing water towards the <br /> pumping well and sweeping the area clean. The proposal appears <br /> to be a reasonable approach to the problem; I did not see any <br /> correspondence in the file to indicate whether or not the EHD <br /> staff have approved or even acted on the proposal . I can contact <br /> my friend at GTI and inquire about the status if you desire. <br /> No other water analayzes had been made on the monitoring wells at <br /> the time the FRP had been submitted, and in the Executive Summary <br /> at the beginning of the report, the statement is made that. . "at <br /> distances greater than 110' from the underground storage tank <br /> location hydrocarbons are not detectable by standard laboratory <br /> methods. " That tank is approximately 200 ' from your property <br /> line. A map included in the Remediation Plan shows that <br /> 1 <br />