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' t Diamond Manteca,CA-November 1993 Groundwatzr Monitoring Page S 4.2 BEI Series Monitoring Wells Three casing volumes were purged from each of the BEI series monitoring wells (BEI-MW4, BEI-MWS 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 During purging/sampling activities, 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 blue ice packets and shipped following the same procedures as defined above The purging/sampling logs are provided in Appendix C 1 4 3 Analybcai Parameters The analytical parameters for both the SRK and BEI series monitoring wells include volatile hydrocarbons (by EPA 8015 M, GC/FID Purge & Trap), benzene, toluene, ethylbenzene, and xylene (BTEX)(Aromatics by EPA 642/8020, GC/FlD Purge & Trap), and total lead (EPA Method 239 2 GFAA) 5.0 ANALYTICAL DATA Organic and inorganic analyses were performed by ACZ Laboratories (CA DOH 1880, expires 4/30195) Copies of the analytical data and chain-of-custody are provided in Appendix D The chain-of-custody clearly documents that the samples were shipped from California to Colorado and also indicates Sample Identification ("SRK-MWI-MAN") The top of the chain-of-custody form clearly states the name and address of ACZ Laboratories in Steamboat Springs, Colorado Table 2 includes all of the available groundwater data for the monitoring wells installed by BEI in 1989 and SRK in 1991 5 1 Monitoring Wells SRK MW1, SRK-MW2 and SRK-MW3 Constituents of BTEX were detected at low concentrations in all three of the SRK series monitoring wells during the November 1993 sampling event Benzene was only detected in monitoring well MW2 at 1 ppb, which 1s a significant reduction from the benzene levels detected in monitoring wells MW2 and MW3 (39 and 40 ppb respectively)during the previous quarterly sampling event in June 1993 Toluene concentrations were detected in all three monitoring wells, ranging from 2 ppb in MW3 to 4 ppb in MW2 These toluene I levels are slightly higher than the levels previously detected during the June 1993 sampling event, which ranged from <0 5 to 1 5 ppb Ethylbenzene concentrations appeared to decrease slightly, and were detected at 0 5 and 1 ppb in monitoring wells MWI and MW2 Ethylbenzene was not detected in MW3 Totat xylene levels significantly decreased in monitoring wells MW2 and MW3 to 4 and I ppb respectively, from 22 ppb(June 1993) Xylene concentrations in MWI increased sightly from <0 5 ppb (June 1993)to 2 ppb )tsoa 27u-Qmy arae Steffen Robertson and Kirsten