Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
ChevronTexaco—U.S. Can/Welty Road,Vernalis, CA. Project No. 06-6102-00-5394-101 <br /> March 10,2004, 2004 Page 5 of 6 <br /> SAIC will also obtain grab groundwater samples from each open borehole and submit them to a <br /> California state-certified laboratory,Friedman&Bruya(FLAP# 1727)of Seattle, Washington, under <br /> proper chain-of-custody protocol for the following chemical analyses: BTEX by EPA Method 826013; <br /> TPHg and TPHd by EPA Method 8015 modified;TPHd by EPA Method 8015 modified with silica gel <br /> cleanup; and PAHs by EPA Method 8270C SIM. <br /> To facilitate the use of grab groundwater samples in a HHRA, SAIC recommends that detection limits for <br /> BTEX and PAHs be requested from the laboratory that are lower than the U.S. Environmental Protection <br /> Agency(USEPA)Region IX Preliminary Remediation Goals(PRGs). The benzene detection limit for <br /> use in a HHRA should be less than the USEPA tap water PRG of 0.34,ug/L. A detection limit of<0.1 <br /> ugIL should be requested for benzene. A detection limit of<1.0,ug/L is adequate for toluene, <br /> ethylbenzene, and total xylenes. Groundwater detection limits for all PAH compounds should be <br /> requested at<0.01 ug/L except for benzo(a)pyrene and dibenzo(a,h)anthracene, which should be <br /> requested at<0.005 pg/l,to ensure the grab groundwater data is adequate for use in a HHRH. <br /> TASK 4—QUARTERLY GROUNDWATER MONITORING AND SAMPLING <br /> The four existing on-site wells(MW-1 through MW4)will be sampled and analyzed on a quarterly basis <br /> for a minimum of four consecutive quarters. SAIC also recommends incorporating well WFSMW-1 <br /> located on the WFS property into the quarterly monitoring and sampling program. Groundwater samples <br /> collected will be submitted to Friedman&Bruya,under chain-of-custody protocol, for the following <br /> chemical analyses: BTEX by EPA Method 802113; TPHg and TPHd by EPA Method 8015 Modified; <br /> TPHd by EPA Method 8015 Modified with and without silica gel cleanup; and PAHs by EPA Method <br /> 8270C SIM. <br /> Groundwater monitoring wells containing separate phase oil (SPO) or sheen will not be sampled. SAIC <br /> will measure and record SPO thickness. This data will be summarized in a table and included in the <br /> quarterly monitoring and sampling report. SAIC will evaluate any wells observed with SPO and <br /> recommend mitigation measures such as vacuum extraction or the use of an absorbent pad or sock to <br /> evacuate any SPO observed in the wells. Purge water will be drummed and properly stored at the site to <br /> be disposed of by ChevronTexaco. Groundwater will be collected in general accordance with SAIC field <br /> procedures and the Second Draft Revised Technical Approach to Site Evaluation and Decision-Making, <br /> Old Valley Pipeline Sites(Geomatrix, 2002). <br /> Task 4.1 -Quarterly Monitoring and Sampling Reporting <br /> 1 After receiving the chemical test results, SAIC will prepare a letter report documenting the quarterly <br /> sampling procedures and findings. The letter report will include the following: <br /> • A site plan; <br /> • Groundwater elevations and flow direction; <br /> • A summary of analytical test results; <br /> • A tabulation of product thickness,and quantity removed, if any; and <br /> • Copies of the laboratory certificates of analysis. <br /> SAIC will present this report to ChevronTexaco 30 days after receipt of the analytical test results. A total <br /> of four separate reports will be presented to ChevronTexaco. <br /> TASK 5—SUBSURFACE INVESTIGATION REPORT <br /> Following receipt of the chemical analytical results, SAIC will evaluate whether soil and groundwater has <br /> been delineated northeast of GMX-12 and downgradient of the subject site. SAIC will prepare a <br />