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Langston's Market 1561 S Seventh Striet, Lathrop, Califn;nra October S, 1995 Interim Secondary Souree Removal s& ltfitnitin ing Ur'ell R placentent Page: 7 ' C) The casing and end caps were threaded, no PVC cement was used The filter park extended two feet above the perforated zone A Bentonite seal three feet thick was placed in the annular space above the filter pack followed by a cement ' grout to the surface The wells were surveyed by a State-licensed surveyor and groundwater elevations ' calculated for gradient determination (Figure b, Table 3, Appendix F) 35 Well Development and Sampling ' The wells were developed until the well hater appeared eared clear of sediment, or until P an appropriate number of well volumes (based upon the judgment of the ' responsible professional) had been evacuated The water produced during well development was containerized and left on-site it, 55-gallon drums, or other ' suitable containers for disposal as hazardous waste if deerned necessary upon receipt of laboratory results DIS00sal will be the responsibility of the client unless other arrangements have been niade The wells were allowed to stabilize fo- forty- eight (48) hours prior to sampling All soil and groundwater samples were pi operly labeled with date collected, project number, sample coordinator, and sample identification Field records document the above information and other significant data, such as tianies of on- site personnel, sampling methods, elate and time of sampling, the number of well volumes i emoved before sampling preservatives lidded (if any) and any filtration performed on samples (Appendix U) The samples were refrigerated iirnnediately for delivery to the :ab;.ratory .and were under no circumstances opened by anyone other than laboratory personnel Chain of Custody records were mainhined at all times (Appendices A & B) 3.6 Soil Sampling P g All soil sampling equipment was thoroughly steam-cleaned before and between sampling to prevent cross Contamination Relatively undisturbed soil samples were taken at intervals of not more than 5 feet in order to evaluate the subsurface materials Borings EW-1 and MW-2 were continuously sampled from 10 feet to the total depth This was dove to obtain detailed lithologic data for vertical definition and to identify and sample any potential aquitard(s) by laboratory hydraulic conductivity analysis Additional soil samples were collected in each boring, except MW 3, from a clay interval between 27 to 33 feet b g l (Figures 4 & 5, Appendix C) l hese samples were analyzed for hydraulic conducts aty