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Del Monte Foods <br /> Page 2 <br /> The "Conceptual Remediation Plan" prepared for this site by CH2M <br /> Hill was discussed. It is a combination of air sparging and soil <br /> vapor extraction that has been proposed to remediate the petroleum <br /> hydrocarbons in the soil and groundwater in the area of monitoring <br /> well (MW) one . There is over 140 feet between MW1 and down- <br /> gradient MW2 which is evidencing high levels of petroleum <br /> hydrocarbons in the groundwater. The next down-gradient well MW6 <br /> which is not evidencing contaminants is about 600 feet away from <br /> MW2 . In addition, MW7D which is monitoring the groundwater at a <br /> depth of 133 feet has evidenced some petroleum contamination in the <br /> groundwater so vertical migration of the contamination is of <br /> concern as well as lateral . The interim remediation proposed in <br /> the "Conceptual Remediation Plan" can proceed but further <br /> definition of the contamination must be done and a Corrective <br /> Action Plan that will remediate all of the soil and groundwater <br /> contamination must be submitted. <br /> PHS/EHD recommended that monthly measurements of the monitoring <br /> wells occur and the gradient information be correlated with <br /> operation of the three Del Monte production wells to further <br /> confirm the gradient . CH2M Hill presented pumping records and <br /> gradient maps from past measurements which they feel clearly <br /> indicate that when the production wells are pumping the groundwater <br /> flows to the northwest and when the production wells are not <br /> operating the groundwater flows to the west . <br /> The pumping of the production wells appears to have pulled the <br /> groundwater contamination off site and may have also caused <br /> vertical migration. PHS/EHD requested an upgradient on-site <br /> monitoring well since the crosstown freeway prohibits any off-site <br /> up-gradient well placement . In addition, PHS/EHD requested two <br /> monitoring wells (one shallow, one deep) be placed in the City of <br /> Stockton right of way between MW2 and MW6 to further define the <br /> extent of the contamination both laterally and vertically in the <br /> down-gradient direction. CH2M Hili suggested that push point <br /> sampling along the City of Stockton right of way and the southeast <br /> border of the site be conducted in order to decide the correct <br /> placement of these monitoring wells . PHS/EHD concurred with this <br /> suggestion. <br /> CH2M Hill stated the piezometers, air sparge and vapor extraction <br /> wells would be installed by November 14, 1994 . Flow rates, <br /> groundwater elevations, dissolved oxygen in the groundwater, and <br /> contaminant concentrations in the vapor will be monitored monthly <br /> during start-up of the system. <br /> PHS/EHD stressed the importance and necessity of hydraulic control <br /> of the groundwater contaminant plume at this site . PHS/EHD stated <br /> the on-site and off-site groundwater monitoring wells should be <br /> installed and data from field tests compiled by January 1995 so <br /> that a Final Remediation Plan (Corrective Action Plan) can be <br />