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IfL I � area, to ascertain whether any supply wells are located near the site. According to Mr. Eric Marr, operations manager in the Stockton field office, drinking water for the entire Port of Stockton complex, as well as all residential areas E� east and southeast of the complex, is supplied via pipeline from the Stockton municipal supply system. Mr. Marr stated that there are no operational municipal supply wells within one-half mile of the Port of Stockton due to the "poor quality" of delta water. The Port maintains a single, private water well which was installed in December 1990 located immediately north of the Port administration building (about 1,700 . feet southwest of Site 1) which is used solely for lawn irrigation. The driller's log for this well indicates the well is perforated from 105 to 145 feet bgs, and has a sanitary seal from 0 to 50 feet. According to Port maintenance personnel, the only other wells located within the Port complex are located along Navy Drive on the western margin of the Port, more than 4,500 feet southwest of Site 1. These wells have been abandoned and do not supply water to the surface. o The Port of Stockton has been an industrial site for more than 60 years. The J reasonably anticipated future use of the site is also industrial. As.such, the ; likelihood of any new water wells being drilled in the vicinity of Site 1 for.the 4 purpose of supplying drinking water to humans is minimal. O The risk of inhalation of MTBE or dermal contact is minimal since the MTBE is confined to the subsurface and much of the site is currently paved. o The risk to aquatic organisms in the deep water channel appears minimal for the }j following reasons: (a) MTBE was not detected in groundwater collected in borings B1-1 or B1-3. Both these borings were located north of B1'-2 (where MTBE was detected), suggesting that groundwater is not flowing northward `A toward the channel, (b) northerly groundwater flow .is unlikely in this area in general, as the presence of the deep water channel likely serves to maintain, southerly hydraulic gradients, and (c) even if MTBE introduced to.groundwater �i near the site did migrate northward, the concentrations would' be greatly attenuated by dilution during groundwater transport and contact with channel water. in summary, current and reasonably anticipated future site use indicates that beneficial use of groundwater near Site 1 is not currently impaired, and should not be expected to become impaired, by MTBE in groundwater at or near this site. Overall, the risk to human health and safety and to the environment appear minimal. 7 981I7uKVRP SMuST1NV.R.Pr t � BOYAJIAN & ROSS, INC. Environmental Scientists& Engineers