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U-Haul#709-50 Preliminary Site Conceptual Model Blaes Environmental December 15,2006 Mrecorded on the field data sheets Purge water was stored in a 1,000-gallon polyethylene tank located on the property, pending proper recycling and disposal Following purging, groundwater samples were collected from U-Haul's on-site and off-site groundwater wells using a new polyethylene disposable bailer for each well Prior to sample collection, the depth to groundwater was measured to confirm that the groundwater level had recovered to within 90% of its original level The water level measurements, sample name, time, and container type were recorded on sample data sheets Groundwater samples collected from the site were contained in appropriate sample bottles supplied by Sequoia Analytical (Sequoia) Following collection, the groundwater samples were placed on ice and transported, under proper chain-of-custody protocol, to Sequoia (a California state certified lab) of Sacramento, California for analysis 4.4 3 Groundwater-Sample Analysis The groundwater samples collected during the third quarter 2006 groundwater monitoring event were analyzed for Total Petroleum Hydrocarbons — diesel range (TPHd), and Total Petroleum Hydrocarbons -- gasoline range (TPHg) according to U S Environmental Protection Agency (EPA) Method 8015, Volatile Organic Compounds (VOC's) including benzene, toluene, ethylbenzene, total xylenes (BTEX), fuel oxygenates including methyl tert-butyl ether (MTBE), tert-butanol (TBA), di-isopropyl ether(DiPE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME), I,I-Dichloroethane (1,1 DCA), 1,2- Dichloroethane (1,2 DCA), and 1,2 Dibromoethane (EDB) according to EPA Method 8260 4.4.4 Groundwater Analytical Results Laboratory analytical results for the third quarter 2006 groundwater sampling event, which included two sample groups middle (B) and lower (C) casing samples, revealed substantial variation between the two groups Blaes Environmental has observed a wide range of fluctuations in VOC concentrations during the groundwater monitoring program The fluctuation in VOC levels is likely attributed to the seasonal fluctuation of groundwater elevation as the groundwater interface moves in relation to the smear zone A summary of the analytical results for the September 2006 sampling event is presented in Table 6 A copy of the corresponding laboratory analytical report and chain-of-custody documentation is provided in Appendix L Analytical results of groundwater samples collected from the well casings screened across the groundwater interface (middle `B" casings) indicated that the highest concentrations of hydrocarbons in groundwater at the U-Haul site are in monitoring wells MW-1B, MW-4B, and MW-3B (0 06 feet of free product) Page 14