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0 0 GROUND WATER MONITORING WORK PLAN DREDGE MATERIAL DISPOSAL SITE 1,ROBERTS ISLAND,PORT OF STOCKTON 3.2.2.3 Survey Well Locations A licensed surveyor will vertically locate the newly installed monitor well relative to mean sea level (msl), to within 0.01 feet, and laterally within the NAD 23 coordinate system. The elevation of the adjacent ground surface will be surveyed to within 0.1 feet msl. 3.2.3 Task 7— Quarterly Ground Water Monitoring Ground water monitoring will be performed quarterly in the seven newly installed monitor wells at the site. One complete round of ground water monitoring will be performed prior to issuance of the Technical Report described in Task 8. The following describes the procedures to be performed. 3.2.3.1 Ground Water Sampling At each well, depth to water and total well depth will be measured to the nearest 0.01 foot with an electronic water-level indicator. Following depth-to-water measurements, a minimum of three casing volumes of ground water will be purged using disposable bailers or a peristaltic pump. The temperature,pH, conductivity, and dissolved oxygen(DO) in the purged water will be monitored in the field during the well purging process. Purging will continue until water parameters stabilize to within 10 percent of successive measurements. Samples will be collected after the water level has recovered to within 80 percent of the original volume in the well. If the well is purged dry, additional purging will not be performed and samples will be collected after the water level has recovered to within 80 percent of the original volume in the well. Ground water samples will be collected into laboratory prepared bottles using a disposable bailer or peristaltic pump. The bottles will promptly sealed, labeled, and placed in a chest containing ice pending transportation to the analytical laboratory. All sampling equipment will be cleaned using a liquinox solution and water rinse after uses between each monitor well. Wastewater generated during the well purging and decontamination activities was placed in 55-gallon Department of Transportation(DOT) drums. The drums will be sealed and labeled for temporary storage at the site. Disposal options will be identified based on the analytical results of the water samples. 3.2.3.2 Ground Water Sample Analysis All water samples will be analyzed for the following constituents, which are listed in the WDR: ■ pH and electrical conductivity will be measured in the field ■ Total dissolved solids by EPA Method 160.1 January 2005 Page 19 Environmental Risk Services,Corp.