ARCHIVED REPORTS SOIL AND GROUNDWATER INVESTIGATION REPORT

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APPENDIX B: FIELD, SAMPLING,AND ANALYTICAL METHODS ' B.1. DRILLING During March 12 and 13, 2007, SAIC observed RSI Drilling(C57#802334) advance five soil borings ' (see Figures 2a, 2b and 3a, 3b) utilizing a Geoprobe®6620DT direct-push,truck-mounted drill rig. The soil borings were advanced to a total depth ranging from 14.5 to 27 feet below ground surface (bgs). In accordance with the approach prescribed in the Second Draft Revised Technical Approach to Site Evaluation and Decision Making, Old Valley Pipeline Sites(Geomatrix, 2005 update), and to the extent practicable, SAIC attempted to collect soil samples from the target depth, or in the event of contamination, from the most affected soil interval. The completion of soil borings generally conformed to SAIC Field Technical Procedure [FTP]No. 525, "Soil Sampling Using an Auger". All Geoprobe® borings were advanced using direct push drilling equipment equipped with 3.25-inch diameter Dual Tube rods along with a continuous coring device used to collect soil samples. Dual Tube tooling was selected to provide a seal when sampling through saturated soils and to facilitate the installation of pre-packed ' well screens explained in section B.3. The samples were screened using photoionization detection (PID) equipment,using procedures consistent ' with SAIC FTP No. 750, "Field Measurement Procedures—Organic Vapor Detection," in order to detect the presence of residual petroleum in soil. The soil was logged in general accordance to the Unified Soil Classification System as presented in American Society for Testing and Materials 2488-90 under the ' supervision of a California Professional Geologist. Additionally, other information was entered into field logbooks to document where, when,how,and from whom any vital project information was obtained, using procedures described in SAIC FTP No. 1215, "Use of Field Logbooks." Following completion of the soil borings,each open borehole was plugged and abandoned according to San Joaquin County Public Health Services(SJCPHS)requirements. B.2. SOIL SAMPLING Soil samples were collected into U.S. Environmental Protection Agency (EPA)-approved containers and submitted to a California-certified laboratory,Lancaster Laboratories(Lancaster) in Lancaster, Pennsylvania, under SAIC chain-of-custody protocol and analyzed for the constituents of concern(CDCs). ' SAIC also collected soil samples from less than 10 feet bgs for use in a human health risk assessment. Soil samples collected for the risk assessment were analyzed for the COCs. For more information,refer to Appendix D, Data Usability Summary and Laboratory Reports. B.3. GROUNDWATER SAMPLING After drilling to total depth,pre-packed well screens were installed in the borehole. The pre-packed well ' screens, manufactured by Geoprobe Systems, were installed in general conformance with American Society for Testing and Materials(ASTM)Method D6725-04. The pre-packed well screens were constructed of 3/4 inch-diameter, 0.010-inch machine slotted polyvinyl chloride well casing packed with ' 20/40 mesh sand and encapsulated with a stainless steel screen. External diameter was 1.5 inches. SAIC collected grab groundwater samples into EPA-approved containers using a peristaltic pump and disposable tubing. Groundwater parameters such as temperature,pH,electrical conductivity, and turbidity were measured during purging. After purging the well casing, groundwater samples were decanted into laboratory-provided bottles, labeled, and placed in an ice-cooled chest pending analysis by Lancaster. 1 B-1 ' From cfaSolutmons