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r . It is our understanding that a City Municipal Well occurs at a distance of about 1,000 feet north of the site (in the apparent downgradient direction) This well is apparently active but is not currently pumping water A water tower is located either gust above or very near the well The assumed groundwater flow direction at the Boyd site is northerly Conclusions and Recommendations Six exploratory borings were drilled m and around the former underground storage tank pit next to the Public Works Building at the Boyd Service Center The bonngs revealed TPHG, TPHD, MTBE and Bunker Oil in borings adjacent to the former tank pit and north of the building Separate phase product was observed in Borings B-3, B-4 and B-5 Residual contaminants depleted in BTEX are interpreted present in the tank pit vicinity Dissolved MTBE and low levels of TAME and TBA are also present in groundwater Separate phase product and sheen were observed at the tank pit and in the assumed downgradient direction, migrating under the Public Works Building Since data was collected from uncased boreholes in which groundwater had not stabilized, a plot of groundwater was not prepared but a northerly groundwater flow is assumed The contaminant distribution indicates tank leakage has reached groundwater and moved in a roughly northerly direction The northerly and easterly extent of the dissolved plume was not . mapped with this phase of assessment It is our understanding that a City Municipal Well occurs about 1000 feet north of the site Further work is warranted at this time, and a work plan should be prepared for submittal and review by PHS EHD Wright recommends the following • Additional exploratory borings should be placed to the east of the tank pit and north of the Public Works Building to define the extent of the dissolved plume jc • A large surface water tower and potential a Municipal Well are located about 1,000 feet north of the site It is our understanding that this is an active well location Wright recommends a review of the Municipal Well seal and the well log to check well seal C)'V11 V) placement and depth Given the large dissolved MTBE concentration observed in Boring �%C'B-3 as well as presence of dissolved TAME and TBA, a one-quarter mile well survey should be performed to identify any other nearby water wells - V o ec�t50 0 • The elevated contaminant concentrations and presence of separate phase product indicate that additional source removal in the former tank pit area is warranted This would lessen 'A 1-1)5 the residual available that could become a dissolved groundwater problems • At least three groundwater monitoring wells should be placed on-site at this time to start a A--a f,-4+, quarterly monitoring program The initial well placement should be near the former underground tank pit and down apparent gradient (north) of the building in the parking lot Wright anticipates that quarterly monitoring for TPHG, TPHD1 BTEXjMW,,MTBE r �r