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R604 UPDATE 17 4-27-1993 <br /> INTRODUCTION <br /> . This report includes the results of events occurring at this site <br /> since the 16th Update Status Report, from February 23 , to March <br /> 30 , 1993 . <br /> LOCATION <br /> Regal Station 604 (parcel # 139-020-08) is located at 1448 N E1 <br /> Dorado and Harding way, Stockton, San Joaquin County, California <br /> The site is in projected section 2; TIN, R6E, MDB&M at <br /> approximately 14 feet above mean sea level Initial drilling <br /> (November, 1989) encountered ground water at approximately 32 <br /> feet below sea level (47, below the surface) and flowing in an <br /> east to southeasterly direction, see figures 1, 2, and 3 . <br /> UPDATE STATUS REPORT #17 <br /> RESULTS - WATER <br /> GROUND WATER GRADIENT <br /> The ground water gradient map, Figure 4, has been produced from <br /> the March 30 , 1993 depth to water measurements These <br /> measurements show a relatively flat ridge shaped gradient flowing <br /> towards the northeast (MW4) and southeast (MW2) . Depth to ground <br /> water measurements show a continual rise in ground water <br /> elevation indicating a recharge event, as would be an expected <br /> result of the current rain season. <br /> TOTAL PETROLEUM HYDROCARBONS <br /> Floating Product: <br /> No floating product has ever been observed .in any of the <br /> monitoring wells <br /> Dissolved Petroleum Hydrocarbons in Ground Water (EPA method 5030 <br /> TFH as gasoline) : <br /> With the exception of MW5 and MW2, which contained 370 and 360 <br /> parts per billion (ug/L) respectively, dissolved total fuel <br /> hydrocarbons, gasoline range, were below detection limits for <br /> wells sampled on December 7, 1992 ( MW1, MW3 , MW4 , MW6 and MW7) <br /> MWS has tested below 1 ppm for gasoline range hydrocarbons since <br /> the June 24 , 1991 sampling and the laboratory reported that MW2 <br /> does not match gasoline but contained a single peak All other <br /> wells have tested below 1 gasoline range hydrocarbons since the <br /> March 29, 1992 sampling This analysis substantiates the <br /> removal of hydrocarbons associated with the ground water and is <br /> evident in comparing the ground water samples obtained on <br /> December 16, 1991 to those obtained on March S, 1992 and later, <br /> see Table 1 . <br /> 0 Before vapor extraction, November 21, 1990, gasoline range <br /> hydrocarbons were detected in MWl (2 mg/L) , and MWS (31 mg/L) . <br /> page 1 <br />