SITE INFORMATION AND CORRESPONDENCE

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Appendix A:Field, Sampling,and Analytical Methods The monitoring wells were constructed of 2-inch-diameter, flush-threaded, Schedule 40 PVC well casing with 20 feet of 0.010-inch,machine-slotted well screen backfilled with Monterey 2/12 sand. The well seal was constructed with 5 percent bentonite and neat cement from the top of the filter pack to surface grade. The well head was completed at the ground surface and protected with steel bollards and a well box. On July 17 and again on July 19, SAIC developed the wells in accordance with SJCPHS and SCDER guidelines. Well completion reports were submitted to the Department of Water Resources as required. Well construction details are presented in Appendix B. AA: GROUNDWATER SAMPLING After drilling to total depth, SAIC collected grab groundwater samples from borings SB-22, SB-23, SB- 24, SB-25, SB-30, and SB-36 into EPA-approved containers,using a peristaltic pump and tubing inside a 1-inch-diameter polyvinyl chloride temporary well casing. The samples collected were all noted as turbid,which is a common feature of grab groundwater samples collected from an open Geoprobe® borehole. After purging the well casing, groundwater samples were decanted into laboratory-provided bottles, labeled, and placed in an ice-cooled chest pending analysis. A.5: SAMPLING LOCATIONS/SURVEY METHODS After completion, soil borings were geo-spatially located using a global positioning system(GPS)unit. After installation,the new monitoring well locations were surveyed by a Registered Professional Land Surveyor for horizontal locations and top-of-casing vertical elevations,which were reported as State Plane Coordinates. The survey of newly installed monitoring wells was completed after the field work for this investigation was completed. (The GPS and the monitoring well survey methods were consistent with SAIC Field Technical Procedure(FTP)No. 175,"Field Measurement of Physical and Topographical Features.") A.6: EQUIPMENT DECONTAMINATION The decontamination of sampling equipment,which did not directly contact the samples,was performed in accordance with SAIC Field Technical Procedure No. FTP-400,"Equipment Decontamination." Sample collection devices,which directly contacted the samples,were decontaminated in accordance with Field Technical Procedure FTP-405, "Cleaning and Decontaminating Sample Containers and Sampling Equipment." In general, all non-dedicated equipment that came into contact with potentially contaminated soil or groundwater was decontamintated. Decontamination occurred prior to and after each use of a piece of equipment. For example,the down-hole equipment was cleaned between borings,using a Liquinox/water solution to prevent the possibility of cross contamination. The equipment was decontaminated in a predesignated area on plastic sheeting, and the clean equipment was stored in an uncontaminated area. Specific decontamination procedures for non-dedicated sampling equipment vary by sampler type, and they are more fully described in FTP-405. Disposable equipment intended for one-time use was not decontaminted but was packaged for appropriate disposal. Reusable sampling equipment not coming into contact with potentially contaminated soil samples,but requiring decontamination,included: field test meters;the water-level sounder; direct-push drilling rig cutting shoes,drive heads,piston asemblies, samplers, and other fittings; and stainless steel hand augers and trowels. Specific decontamination procedures employed for these types of sampling equipment are more fully described in FTP-400. A-2 From Science to Solutions-