ARCHIVED REPORTS XR0009532 - Laserfiche WebLink

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' Corrective Action Plan Page 3 Former Manna Pro Site Ile Project No 207 3 February 16,2001 ' 1.2 Current Site Status ' The vertical and lateral extent of the groundwater plume have been deemed adequately characterized by the San Joaquin County Public Health Service — Environmental Health ' Division (PHS-EHD) This agency recently directed that a Corrective Action Plan (CAP) be submitted to describe proposed work to complete the engineered remedial action for this release The plan is based on the results and recommendation in out Feasibility ' Study dated October 20, 2000 As documented in recent reports, the groundwater surface lies some considerable distance above the main body of the contaminant mass This is in contrast to the situation existing at the time of the first GTI pilot study when the groundwater level and the main contaminant mass were near the same elevation 1.3 Proposed Scope of Work The goal of the work described herein is to complete the engineered remedial work for this site This work will be based on the vapor extraction method of contaminant removal and will be aided by air sparging As pointed out in the Feasibility Study, there remains some uncertainty regarding the rate at which hydrocarbons can be removed using this • method The source of the uncertainty is related to the approximately 10 to 20 feet of groundwater column situated over the most severely impacted zone In order to allow for possible adjustments in the spacing of wells and other engineering details, the construction of the remedial system will be completed in two steps, or phases The first phase will consist of the installation of an additional air sparge well The this well and the previously installed well will be used along with the recently installed vapor extraction well in the initial phase of remedial action The system will be operated for up to 3 months while pressure data, vapor extraction rates and other data is collected and evaluated The data will be evaluated to determine whether any adjustments are needed ' in the system design prior to installing the remainder of the system As currently designed, the final remedial system will include 10 air sparge and 10 vapor extraction wells (This total includes the previously constructed vapor extraction and air sparge wells) The following two sub-sections discuss the guiding concepts of the tasks being proposed by this Work Plan, and introduce the major elements of the work that will be needed to accomplish the stated goals 1.3.1 Conceptual Basis In recent years, groundwater at the site has reached historically high levels The surface Iof groundwater has recently been as high as 25 feet bgs, but as late as 1994, the 2937 Veneman Ave, #13240 Geo-Phase Environmental Inc Phone(209)569-0293 Modesto,CA 95356 Fax(209)569-0295 I