ARCHIVED REPORTS_NOTICE OF INTENT FOR INSTALLATION, OPERATION AND MAINTENANCE OF AN OZONE INJECTION GROUNDWATER REMEDIATION SYSTEM

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' 2.4 OS Pilot Testing Groundwater Sampling ' In accordance with our workplan and an October 29, 2008, directive from the CVRWQCB we monitored TPHg, BTEX, FOCs, VOCs and dissolved oxygen (DO) levels upgradient of the target treatment area by collecting groundwater samples from upgradient observation well MW-7; within the source area using wells MW-1, MW-3 and GWX-1; and downgradient of the source area in wells MW-5 and MW-6. The groundwater samples were shipped to MTL for analysis of TPHg under the United States Environmental Protection Agency (EPA) Test Method 8015M, and for BTEX, FOCs, and VOCs under EPA Test Method 8260B. Baseline samples were collected on November 11, 2008, ' prior to the start of any pilot testing activities. We repeated these analyses at the completion of the AS pilot test, after every approximate 30 days of OS pilot testing(March 9,2009, and April 15,2009), and at the conclusion of the OS pilot test(May 11, 2009). ' To address concerns regarding potential impacts to the subsurface environment related to the injection ' of ozone, we submitted supplemental groundwater samples from the above-referenced wells for the following analyses: • Acetone following EPA Test Method 8260; • CrVI following EPA Test Method 7199; ' • Bromate following EPA Test Method 317.1. ' The supplemental sampling was performed weekly from February 9, 2009, to March 30, 2009. The CVRWQCB agreed to modify the supplemental sampling to monthly on April 2, 2009. Baseline levels of the supplemental analytes were also established during the November 11, 2008, groundwater ' sampling event. For each of the groundwater sampling events, we extracted approximately three casing volumes of groundwater from each sampled well using portable 12-volt submersible pumps. We decontaminated ' each pump before and after each use with an AlconoxTM wash followed by potable and deionized water rinses. During the well purging 'activities, we monitored the groundwater for pH, electrical conductivity and temperature. This information is included on Monitoring Well Sampling Data sheets, which are presented in Appendix A. ' Following well purging, we collected groundwater samples from the well by means of a pre-cleaned, dedicated disposable polyethylene bailer. We decanted each sample from the bailer through a low-flow sample release tube into the appropriate laboratory-provided containers. We sealed and labeled each ' sample, placed the samples in a cooled ice chest and subsequently transported the samples to the appropriate laboratory using standard chain-of-custody documentation. 1 Project No.59183-06-02 -5- July 2,2009