Laserfiche WebLink
, <br /> = 1 <br /> File No.2070-2 <br /> 19 December 1991 <br /> Page 10 <br /> during pumping or draining of the aquifer. It is determined from the distance-drawdown graph <br /> based on the calculated trans miss ivity,the zero drawdown intercept value and the distance between <br /> the observation well and the pumped well. The Ove values obtained for the aquifer storage <br /> -- coefficient based on the pumping test data for the Rainbo Bakery site were 0.066,0.022,0.017, <br /> 0.011 and 0.019. The average value was calculated as 0.027. <br /> _4Q—.,,'ONMSIONS <br /> 4.1 Soil Investigation <br /> Our field observations and laboratory analyses indicated that minor ozcurrences of petroleum <br /> hydrocarbon contamination exists within the soil in vicinity of the removed underground fuel storage <br /> tanks. However, according to our investigation, the majority of the petroleum hydrocarbon <br /> contaminated soil was removed foliowing the 1987 tank removal procedures. The few occurrences <br /> of contaminated soil discovered during our groundwater inveaigation appear to be Iimited remnants <br /> of contaminated soil inadvertently left in place following the 1987 soil excavation and remediation <br /> operation. We feel that since the majority of the contaminated sail has been removed, no further <br /> action concerning soil remediation is warranted. <br /> Composite soil samples of the boring and monitoring well cuttings were collected from the onsite <br /> storage drums. The samples were analyzed in a State of California certified analytical laboratory <br /> for the presence of petroleum ►ydrocarbon products. No detectable levels of T?H or AVO's were <br /> _ present in either of the composite soil samples (DC-1 and DC-2). Therefore, the drummed soil <br /> cuttings can be discarded. We recommend the soil be either utilized as fill material on the site or <br /> disposed in a landfill. Copies of the laboratory results fbr soil samples DC-1 and DC-2 are included <br /> in Appendix VIII. <br /> 4.2 Groundwater Investigation <br /> i Our field observations and laboratory analyses indicated that groundwater contamination exists <br /> beneath the subject property as a result of the past leakage of underground fuel storage tanks. <br /> Based on our investigation, it appears that the groundwater contamination extends over an area of <br /> approximately 22,000 square feet (see Figure 10). We feel that a groundwater remediation system <br /> $ should'i a considered for the Rainbo Bakery site. <br /> 5.0 POSSIBLE GROjjMWATER REMEDIA77071 ALIERNA31YE.S <br /> I� Several alternatives exist for remediation of the contaminated groundwater beneath the Rainbo <br /> Bakery in Stockton. The remediation alternatives can be subdivided into two categories; 1 in-situ <br /> remediation and-2) groundwater extraction systems. In-situ remediation involves the treatment of <br /> the contaminated groundwater as it remains in the aquifer. Groundwater extraction systems consist <br /> of extraction of the contaminated groundwater from the aquifer and. treatment following its <br /> extraction. Following are brief discussions of the treatment alternatives and their potential <br /> applications to the Rainbo Bakery site. <br /> J i ANOCRSOR <br /> t CONSUMNG ; <br /> l GROUP <br /> } <br /> r <br />