ARCHIVED REPORTS XR0008945 - Laserfiche WebLink

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from the Orange County Health Care Agency (OCHCA) on August 14, 2002 (letter from Seth J Daugherty to Marvin Katz, 9 August 2002] The task items in the work plan are as follows Task 1 Site screening Task 2 Evaluate likelihood of TBA being derived from gasoline product sold at service stations Task 3 Evaluate biological transformation of MTBE to TBA in the groundwater environment Task 4 Evaluate possible abiotic transformation of TBA from MTBE Task 5 Evaluate possibility of TBA detections being an artifact of sample collection and/or laboratory analytical methods Updates on the progress of this work were provided beginning in September 2002 Task 3 included laboratory microcosms of up to 150 days duration, with the last batch concluding at the end of September 2003 Discussion of the results and conclusions from executing these tasks is included in this report 3. Site Screening A total of 6 sites in Orange County with reported TBA levels in groundwater greater than 50 mg/L (ppm) have been identified by OCHCA, and the available site-specific environmental reports and data have been collected, consolidated, and reviewed Table 3 1 provides a brief summary of site conditions at the initiation of the TBA Study At five of the six sites, measured TBA in groundwater was significantly greater than measured MTBE concentrations, and BTEX concentrations in groundwater at five of the six sites were comparably insignificant Based on the summary results, a review of the hydrogeologic settings, as well as site logistics and history, three sites were selected for detailed follow-up study These sites include 30011 Crown Valley Parkway, 16969 Brookhurst, and 27101 Ortega Highway Table 3 t Summa Information-Orange County sites identified by OCHCA Operating Nominal Nominal Recent Site Activities Facility? Maximum Nominal Maximum MTBE Maximum BTEX Street Cit b TBA b b 1 6011 Crown Valle yes 65 000 340 000 950 Screening modeling completed attenuation Pk Laguna Niguel shown 011 Manchester yes 220 240 600 non-detect Recent VacOps Prior excavation for diesel Buena Park im acts 3 32342 Pacific Coas no 28 000 2 600 36 100 3 triple-nested SVE wells ongoing vapo— r Highway Laguna Beach extract 7101 Ortega Highway no 9 300 390 000 non-detect ank removal and excavation 5an Juan Capistrano 16969 Brookhurst yes 2,500 45000 46 Finalizing site assessment and site conceptual Fountain Valley model 1000 Irvine, Newportyes 250,000 120 000 non-detect F�nal�zing site assessment and RAP �n near Beach uture 2