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The soil samples selected for chemical analyses were placed in a cooler chilled to approximately 4° C (40° F), and sent to SPL Laboratories of Fullerton, California via overnight courier. Sample handling, transport, and delivery to the laboratories were documented using chain-of-custody procedures, including the use of chain-of-custody forms. ' Monitoring Well Installation Following the collection of soil samples, soil borings B-1, B-2 and B-3 were advanced to 65 feet bgs, 70 and 65 feet bas respectively, and converted to monitoring wells MW-1, MW-2 and MW-3 respectively. Wells MW-I and MW-3 were constructed with 15 feet of four-inch inside diameter(ID),0.010-inch machine slotted, schedule 40 polyvinyl chloride (PVC)screen from approximately 50 to 65 feet bgs, and 50 feet of four-inch ID schedule 40 PVC blank casing from the ground surface to approximately 50 feet bgs. Well MW-2 was constructed with 15 feet of four-inch inside diameter(ID),0.010-inch machine slotted, schedule 40 polyvinyl chloride (PVC) screen and from approximately 50 to 70 feet bgs, ' and 50 feet of four-inch ID schedule 40 PVC blank casing from the ground surface to approximately 50 feet bgs. ' The annulus between the screen and the boring was filled with #2112 Monterey Sand. The sand pack in the wells was surged with a surge block to allow the sand to settle and draw the fine grained material out of the sand pack into the wells from the bottom of the boring to approximately 2 feet above the slotted portion.. The wells were developed using a steel ' bailer to remove fine grained materials from the well. Approximately 1 foot of hydrated bentonite pellets were placed on top of the sand pack before grouting the wells. The wells were then grouted to the surface with Portland cement using a grout pump and tremie pipe. The seal of the wells was observed by San Joaquin County Health Department Officials. Following the sealing of the wells a traffic rated well box and locking cap were installed at each wellhead. Well construction diagrams are enclosed in Appendix C. Wellhead Surveying On February 25, 1997 the wellhead elevations and locations were surveyed by Morrow 1 Surveying, Inc. of Sacramento, California. The wellhead elevations are included in Table 1. The complete well survey is included as Appendix D. Groundwater Elevation Measurements On February 25, 1997, the static groundwater elevations were measured in the three groundwater monitoring wells by lowering a decontaminated Solinst groundwater elevation 1 probe and measuring the groundwater elevation to the nearest 0.01 foot. Well elevation ,. data are included in Table 1. Groundwater was encountered during the monitoring well installation at approximately 55 feet bgs, however the water levels rose approximately 10� ' feet following well installation. The calculated groundwater elevation indicates that the groundwater gradient is approximately 0.0025 to the northeast. A groundwater contour map is presented as Figure 3. Groundwater Sampling On February 25, 1997 the monitoring wells were purged a minimum of three well volumes . using a submersible pump. Field parameters were measured during the purging of ' groundwater with a Hydac conductivity/temperature/pH meter.The pH of the groundwater 7 197046a - Stockton