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c " a Z4 Surveying and Water Level Measurements The ground surface and top of each monitoring well casing was surveyed on August 20, 1991 by representatives of Wong Engineering, Inc. to the nearest 0.01 foot elevation above mean sea level (Appendix D). Survey measurements for all well casings we.e made re=ative to the north side of the casing. The survey data was used to calculate groundwater levels (Table 1), and produce a groundwater contour map (Figure 3). Water levels were measured immediately prior to sampling using a conductivity based water level indicator. 2,5 Well Development and Sampling '+ The monitoring wells were developed on August 5, 1991, by hand bailing at least five well volumes of water, from each well using a decontaminated, four-inch, PVC hailer. During rH development, the wells wt.-e also surged using a filled bailer. Development was continued until well water was relatively clear and free of sediment. Prior to sampling, all wells were checked for the presence of free floating product. No free floating product was encountered. Groundwater samples were collected on August 5 and 15; 1991, using one new Vass Technologies disposable tiailer per well to avoid the chance of cross contamination of the wells. Samples were placed directly from the bailer into containers cleaned,preserved and supplied by the laboratory. w All samples were placed in a ziploc bag and sealed with security tape. Samples were stored in a refrigerated ice chest and delivered to Precision Analytical Laboratory, with the exception E of samples to be analyzed for coliform which were delivered to Brown and Caldwell Laboratory. Chain of custody forms accompanied the samples at all times (Appendix Q. _ 2.6 Chemical Analysis All soil and groundwater samples were analyzed by precision Analytical Laboratory for total petroleum hydrocarbons (TPH) as gasoline and benzene,toluene, ethylbenzene, and xylenes (BTEX) by EPA Methods 5030 and.602. In addition, groundwater samples were analyzed for fecal coliform by FPA Method 9221 by Brown and Caldwell Laboratories in Emeyville, California. Laborxtery reports are contained in Appendix E. ' MZ(10-21-91N5rJoo14N1Et 5 ��s