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0 • ' CONCLUSIONS/RECOMMENDATIONS ' Based on a review of the analytical results of the groundwater samples of MW34 through MW3-3 for BTEX, TPHg, and MTBE,the following conclusions are presented ' • Free phase petroleum product has not been detected in any of the wells on the site • MTBE was not detected in groundwater and soil samples taken August 7, 1998 and groundwater samples taken July 9, 1999 and October 22, 1999, hence it is prudent to eliminate MTBE analysis ' from future monitoring events • The BTEX concentrations for all groundwater samples on the October 22, 1999 monitoring event, exhibited a substantial decrease across the board in comparison to the concentrations found during the July 9, 1999 monitoring event This suggests that natural attenuation, which may include intrinsic bioremediation may be occurring in the subsurface ' • The TPHg in MW3-3 was found at a lower concentration of 7,270 µg11 on October 22, 1999 as compared to 8,420 µg/1 for the July 9, 1999 monitoring event However, the TPHg concentrations detected in MW3-1 and MM3-2 were at higher concentrations than in the ' previous quarter This may be due to the change in groundwater direction observed between the two monitoring events The following recommendations are presented for this site • Due to the downward trend of the concentrations of the majority of constituents of concern (COC), suggesting natural attenuation by intrinsic bioremediation, it is recommended that interim in-situ bioremediation techniques be used to enhance the attenuation of COCl To aid in the bioremediation of the dissolved phase PHCs and BTEX, an Oxygen Releasing Compound (ORC), suspended in each of the three wells would be a beneficial and cost- effective interim bioremediation technique It is recommended that ORC filter socks be placed in each well A description of the filter socks, which contain magnesium peroxide, and several ' case studies where ORC has been used to remediate PHCs are included in Appendix C because the magnesium peroxide is contained within inert materials, there is no risk of release of potentially harmful materials to the groundwater ' • Additional groundwater monitoring should he conducted in order to obtain groundwater samples for TPHg and BTEX analyses • Depending on the results of the next quarter of monitoring, a risk assessment should be ' conducted to demonstrate that this site poses low risk to human health and the environment • 1 ust S1W qta 99 doe 6