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%t/ %Wok y Ms. Lori Duncan October 3, 2003 Page 5 of 7 vertical extent of the dissolved plume has been defined, Ground Zerp proposes to advance one soil boring (Figure 6) to a depth of up to 75 feet bgs in the vicinity of the former UST using a direct push drilling rig equipped with a dual-tube system. After pushing the outer rods to a depth of approximately 25 feet to seal off the uppermost water-bearing unit, a CPT probe will be pushed to a depth of up to 75 feet bgs to characterize lithology beneath the site. After lithology has been characterized through CPT, a second hole will be advanced for the purpose of collecting discrete groundwater samples. Groundwater samples will collected using a hydropunch-style sampler from any potential aquifers (high-permeability zones) identified through soil classification. If preliminary hydropunch samples are positive for gasoline constituents, we will re-mobilize to the site at a later date to install a deep monitoring well, the screened interval to be determined from preliminary results. This well will not be installed if the discrete sampling data indicate that deeper zones are not impacted. Well Development,Surveying and Groundwater Sampling The elevation of the top of the casing in each well will be surveyed to an accuracy of 0.01 feet. A minimum of 24 hrs after completion, an experienced field technician will measure static depth to water and then develop the wells by pumping and surging until turbidity is minimized. A minimum of five casing volumes will be purged from each well. Groundwater samples will be collected after pH, temperature, and electrical conductivity have stabilized and the wells have recharged to minimum of 80% of static levels. Groundwater samples will be immediately placed in an iced cooler and submitted to a State-certified laboratory under chain of custody protocol for analysis of TPHg (EPA 8015B), BTEX (EPA 8021B), and oxygenated gasoline additives (EPA 8260B). The EPA 8260B scan will be expanded to include ethylene dibromide (EDB) and 1,2-dichloroethane (1,2-DCA) pursuant to Regional Board requirements. Water generated from well development and sampling will be contained in labeled DOT approved drums. The drums will be stored on site pending laboratory results and the development of disposal options. Investigation of Pumping Influence of Nearby Production Wells Evaluation of Analytical Results Groundwater samples were collected from the facility and the two nearest domestic wells on September 29, 2003. Samples were collected at the spigot nearest the well after opening the spigot for approximately 15 minutes at each location. Samples were collected into 40-m1 glass vials supplied by the laboratory. The samples were transported under chain of custody protocol to Argon Laboratories (FLAP 2359) for analysis of TPHg, BTEX, and oxygenated gasoline additives using EPA methods 8015B, 802113, and 8260B,respectively. woo 1 se y.chYr epo r t sl w o rk p I a n.m w s