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Diamond Lodi,CA-November 1993 Groundwater Monitoring page 4 noted that the groundwater elevations varied by only a few tenths of feet. Based on calculations using data during the November 29, 1993, sampling event, the groundwater gradient has a very slight gradient (0.2 %) in a southerly direction. It should also be noted that the groundwater gradient is extremely flat (the difference in static groundwater elevations between the highest and lowest point is roughly 0.2%, or approximately 0.4 feet vertically over 140 feet laterally. Copies of the hand calculations and cross-sections used in determining the groundwater gradient are provided in Appendix B. 1 4.0 GROUNDWATER SAMPLING Three casing volumes were purged from each of the SRK monitoring wells using dedicated disposable bailers equipped with nylon cord. The purged volumes were measured in a calibrated bucket,then emptied collectively into a 55-gallon drum located in the covered material storage area that extends along the south wall of the former lumber storage area. The drum lid was securely fastened after the three wells were rsampled. The analytical groundwater samples were collected after more than 3 casing volumes were purged from each well, and the Ph, temperature and conductivity had stabilized. "Stabilized" is defined as three consecutive reading within 15% on one another. The analytical groundwater samples were collected in laboratory grade sampling containers and placed in a cooler containing frozen ice and blue ice packets,and shipped following strict chain-of-custody procedures to a California certified laboratory (ACZ Laboratories) for analysis. The analytical parameters include volatile hydrocarbons (by EPA 8015 M,GC/FID Purge&Trap), benzene, toluene, ethylbenzene, and xylene (BTEX)(Aromatics by EPA 60218020, 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 ji rapidly (EDB is converted almost completely within 2 months to ethylene) and also in water, where it hydrolyzes to ethyleneglycol and bromoethanol (under neutral conditions and ambient temperature the half- life of the reaction is 5-10 days). 5.0 ANALYTICAL DATA ' 5.1 Groundwater Data Organic and inorganic analyses were performed by ACZ Laboratories (CA Lab #E608). Copies of the analytical data and chain-of-custody are provided in Appendix C. The chain-of-custody clearly documents that the samples were shipped from California to Colorado and also indicates Sample Identification ("SRK- MWI-LODI"). The top of the chain-of-custody form clearly states the name and address of ACZ Laboratories in Steamboat Springs, Colorado. Copies of the analytical data for the municipal wells are provided in Appendix D. Copies of the purging logs are provided in Appendix E. Table 2 includes all of the available groundwater data for the monitoring wells installed by SRK in 1991. ' 72504,24%-QLdy.Lod Steffen Robertson and Kirsten