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' Diamond Manteca CA June 1993 Groundwater Momtonng Page 5 approximately five casing volumes (roughly 55 gallons) from each SRK series wells Purging causes a localized cone of depression around each monitoring well Because the cone of depression causes a Iocalized drop in the static water level, the lighter, volatile contaminant constituents (typically located on the static water surface) are allowed to be drawn into the screened interval of each monitoring well The purged casing volumes(approximately 55 gallons from each SRK series monitoring well) were pumped into recycled drums that had previously contained cuttings generated during on-site drilling activities The contents of selected drums was spread on-site following regulatory approval during the February 1993 ' sampling event, as described in SRK's Quarterly Groundwater Monitoring Report dated April 1993 Special care was taken to insure that the recycled drums held water A small leak was detected in the drum containing water purged from SRK-MW I This purged water was carefully hand bucketed into a water tight drum The drum lids were securely fastened after each well was purged and sampled Analytical groundwater samples were collected using a pre-cicaned stainless steel bailer equipped with nylon rope These samples were collected after more than five casing volumes were purged from each well, and the pH, temperature and conductivity had stabilized "Stabilized" is defined a three consecutive readings within 15%of one another The analytical groundwater samples were collected from the top of the stainless steel bailer and were preserved in laboratory grade sampling containers These samples were placed in a cooler containing bags of crushed ice and blue ice packets, and shipped following strict chain-of-custody procedures to a California certified laboratory (ACZ Laboratories) for analysis Copies of the Geologic Logs and Monitoring Well Construction Diagrams are provided in earlier SRK monitoring reports Copies of the purging/sampling logs are provided in Appendix C 4.2 BEI Series Monitoring Wells rThree casing volumes were purged from each of the BEI series monitoring wells (BEI-MW4, BEI-MW5 and BEI-MW6) using dedicated disposable bailers equipped with nylon cord The purged casing volumes ' were measured in a calibrated bucket, then emptied collectively into a 55-gallon drum located near BEI- MW5 Monitoring wells BEI-MW5 and BEI-MW6 were bailed dry, however, recharged to within 80% of the static water level before bailing During purging/sampling activates, strong petroleum odor/sheen was observed on the purged water surface ' Analytical groundwater samples were collected using dedicated disposable bailers These samples were collected after more than three casing volumes were purged from each well, and the pH, temperature and conductivity had stabilized(as defined in 4 1 above) The analytical groundwater samples were also placed in a cooler containing bagged crushed ice and blue ice packets and shipped following the same procedures as defined above The purging/sampling logs are provided in Appendix C ' 4 3 Aimlytual Parameter The analytical parameters for both the SRK and BEI series monitoring wells include volatile hydrocarbons (by EPA 8015M, GC/FID Purge & Trap), benzene, toluene, ethylbenzene, and xylene (BTEX) (Aromatics by EPA 602/8020, GC/FID Purge & Trap), and total lead (EPA Method 239 2 GFAA) Ethylenebromide (EDB) was not included in the suite of analytes, because EDB degrades in soil very rapidly (EDB is converted almost completely within 2 months to ethylene) and also in water, where it r1110111"" vt>Mm Steffen Robertson and Kirsten