SITE INFORMATION AND CORRESPONDENCE

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Mr. Kelly Williamson October 28, 1985 Page Two In the process of installing the bore holes, soil samples were taken with a split spoon sampler every five feet from the surface to the groundwater to classify soil types and screen for contamination. Each sample was screened, using a 5A Toluene drager tube and pump. All samples that indicated a detectable reading on the drager tube were sent to Twining Laboratories for analysis. As of this date, the results of these analysis ,have not been recieved, but they will be forwarded to you as soon as they arrive. I am attaching a chart on all the groundwater monitoring data that has been performed between 6-22-85 and .10-27-85, along with the monitor well elevations, and the laboratory results of the water samples taken on 8--26-85 from MW#6 and MW#7- Due to the fact that raw product has been found on the surface of the groundwater in MW#5 in significant amounts and the analysis of the water samples taken from MW#6 and MW#7 show relatively high concentrations of -dis- solved hydrocarbons, it would be my recommendation that a hydrocarbon recovery system, utilizing a groundwater depression pump and a hydrocarbon recovery pump be installed as soon as possible to begin remediation and restoration of the contaminated area. 1 am attaching drawings of a proposed hydrocarbon recovery system and a re- covery well . I recommend a 24" recovery well approximately 70 feet in depth, to provide a high recharge capability that will allow a sufficient depression` of the groundwater, thereby creating a cone of influence large enough to be effective in causing the effected groundwater and phased product to return to the recovery well for treatment or recovery. In surveying this location for the possi le placement of a recovery well and :. system, it was noted that one of the underground storage tanks, which tested tight, is stili in place. Since this location -is no longer in operation , I would propose that this underground tarok be placed into service as the re- covered product tank for the recovery system. The use of this tank would speed installation and reduce the overall cost of the recovery system. Attached, you will find a site drawing with the proposed recovery well and system locations indicated. By placing the recovery system under the canopy in the area of the north pump island, it will provide more security anld the existing electrical conduits can be utilized, reducing the installation cost even further. A study will have to be made on the dispi sit,i,on of the recovery system effluent, if a recovery system is decided upon. Discharge of the recovery system efflu- ent might possibly be handled in one of the following ways: (1) Into the sanitary sewer, when that project is complete, and i-f allowed by the Waste Water department of the City of Stockton (2) Into the storm sewer system, if allowed, or (3) Reinjection beds on the perimeter of the property.