ARCHIVED REPORTS_XR0006716 CASE 1

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4.0 CONCLUSIONS S , RECOMMENDATIONS AND PROJECT STATUS Three additional monitoring wells (MW-7, MW-8, and MW-9) were installed northwest and west of the site Nine sod samples collected from the well borings were submitted for chemical analysis The three new and six existing groundwater monitoring wells were monitored and sampled as part of the second quarter 2005 monitoring and reporting program Between March 22, and April 25, 2005, the groundwater surface dropped an average of 0 26 feet, the groundwater gradient increased from 0 0049 to 0 0071 foottfoot, and the groundwater flow direction remained toward the north-northeast Based on the sod and groundwater analytical results, gasoline compounds in the subsurface remain defined to the vicinity of well MW-2 and the former UST system Previous investigations have shown that the former on-site water supply well and nearby domestic wells have not been impacted by gasoline compounds released from the former UST system In general, the concentrations of gasoline compounds in groundwater beneath the site have declined, most likely in response to prior source removal efforts and natural attenuation processes Given the low and rapidly declining concentrations of gasoline compounds in groundwater, active soil and groundwater remediation has not been necessary to reduce concentrations to below water quality goals MTBE has not been detected above 5µg/l (the secondary California Maximum Contaminant Level [MCLI) since March, 2003 (in well MW-2), and no other gasoline compound has exceeded its respective MCL, in any well, over the last four quarters Based on these conclusions, Ramage Environmental recommends that the nine monitoring wells continue to be monitored and sampled for the remaining two quarters of 2005, after which, should gasoline compounds remain below their respective MCLs and/or below reporting limits, the site should be considered for regulatory closure ! 13