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1 <br /> 5.0 Conclusions and Recommendations r <br /> Work performed during the second quarter of 1997 included the monitoring and sampling of the <br />' three on-site monitoring wells Since the last monitoring event in March 1997, groundwater <br /> elevations have fallen an average of 0 3 feet Groundwater flow was determined to be in a <br /> easterly direction at a gradient of approximately 0 002 feet/feet Two of the three groundwater <br />' samples collected during the quarter contained detectable concentrations of gasoline <br /> hydrocarbons The groundwater sample collected from MW-2 contained 200 yg/L of TPH- <br />' gasoline and the sample collected from MW-3 contained 250/tg/L, in addition to 2 9 mglL of <br /> benzene and low concentrations of ethylbenzene and xylenes The analytical results from this <br />' quarter indicate stable petroleum hydrocarbon concentrations since the last sampling event <br /> Although groundwater surface elevations above the screened interval of the monitoring wells <br /> may be affecting the reliability of the groundwater gradient and flow characteristics and the <br />' representativeness of the groundwater analytical results, release of hydrocarbons to the <br /> groundwater persists As such, IT recommends the installation of Oxygen Releasing Compound <br /> (ORC) filter socks at the site The ORC technology is a passive bioremediation process which <br /> stimulates the growth of the indigenous petroleum degrading bacteria with the introduction of <br /> oxygen through moisture activated, slow release, filter socks containing magnesium peroxide <br />' (M902) Without an induced oxygen source, the available oxygen in the soil and groundwater <br /> can be depleted, and thus limit the rate of degradation of the hydrocarbons No adverse by <br />' products are expected because of the addition of the magnesium peroxide to the saturated zone <br /> IT recommends that well MW-3 be considered as the treatment well, and that wells MW-1 and <br /> MW-2 continue to be monitored for a n mmum of two successive quarters prior to making a <br />' closure recommendation <br /> r <br /> 4 <br /> 1 <br />