SITE INFORMATION AND CORRESPONDENCE_FILE 1

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I CLEARWATER G R O U P Environmental serviees It is recommended that MW-9 be installed after results from the First Quarter 2009 monitoring are evaluated to assess whether the additional data impact our understanding of site conditions. Wells AS-1 and DPW4 Two wells, Air Sparge (AS- 1 ) and Dual-Phase Extraction Well (DPW- 1 ) were installed at the site in February 2002. The wells were installed to assess whether soil venting and/or air sparging could be a viable remediation method. Initial testing was conducted but the system was not installed because of subsurface conditions. The two wells are located in the central part of the groundwater plume. Borings AS- 1 and DPW- 1 were drilled to depths of 25 and 30 feet with screened sections of 22 to 25 feet and 10 to 30 feet, respectively. Well DPW- 1 was sampled twice in March 2002, and elevated levels of benzene were detected at concentrations of 42,000 and 48,000 micrograms per liter (µg/L) or parts per billion (ppb). DPW- 1 and AS4 were sampled in December 2008, and benzene was detected at 560 µg/L and 4,600 µg/L, respectively . Because of the limited sampling points at the central portion of the plume, Clearwater recommends adding these two existing wells to the quarterly sampling program. Additional data at these locations will assist in our understanding of the lateral limits of the plume in the center and to the north. Measurement of groundwater parameters in these wells will help assess whether natural degradation is occurring. Site Conceptual Model A Site Conceptual Model (SCM) isq in the process of being prepared by Clearwater and will be available for discussions in a short period of time. The model will provide maps and cross- sections of the source and extent of contamination, as well as sensitive receptors including both__ groundwater sources and surface water impacts . Description of release scenarios and assessment of the amount of contaminant remaining in the subsurface will be made. The compiled data will be presented as maps, site plans, tables, boring logs and other figures and documents as warranted. In the future, the model will be updated as deemed applicable. Monitoring Schedule All wells will be gauged during each monitoring event. Information, including depth to water measurements, presence of "free product," odor and other physical parameters will be documented and recorded. Sampling and gauging will be performed as previously described. Table 1 (attached) presents the current sampling program, as we currently understand it. Clearwater recommends wells AS - 1 and DPW- 1 be included in the sampling program and sampled on a quarterly basis. All groundwater samples collected will be analyzed for Total Petroleum Hydrocarbon as gasoline (TPH-g), Benzene, Toluene, Ethyl Benzene and Xylene (BTEX,) and the analytes tested for wells MW-511 and MW-7 will also include the five fuel oxygenates (methyl-t-butyl ether [MTBE], disopropyl ether [RIPE], ethyl-t-butyl ether [ETBE], ZB178N 2 of February 11 , 2009 Barnes Trucking Response to Regulator