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Project Number 1804BK54 April 11,2013 The HVE operations conducted from December 2012 through February 2013 provided data that confirmed this finding. The data indicated that residual PCE in groundwater is very minor and localized. This conclusion is based on the following: • Dissolved-phase concentrations of VOC's prior to HVE events continued to show significant declining trends indicating the effectiveness of site remediation combined with natural attenuation of contaminants; • HVE operations reduced dissolved-phase concentrations 56% at EX-1BB (from 23.3 micrograms per liter (µg/L) to 10.2 µg/L) and 66% at MW-7BB (from 30.7 pg/L to 10.3 pg/L); and • The radius of groundwater extraction capture, during high vacuum extraction operations, was significant as groundwater elevation drawdown was measured in monitoring wells located greater than 130 feet from EX-11313 and greater than 110 feet in the downgradient direction and greater than 300 feet in the upgradient direction from MW-71313. In concept, had there been a significant concentration of VOC's in the subsurface soils, "smear" zone or groundwater within the capture radius of the extraction wells, the concentrations after HVE would have increased instead of decreasing, as the HVE would have drawn the higher concentrations to the extraction wells. The HVE data was relayed to the Case Oversight Officer for the CRWQCB via telephone communication on April 8, 2013. In that conversation, the Case Officer indicated that the Site warranted Site Closure and that the Site Decommissioning Workplan could be prepared and submitted. 2.0 SITE DECOMMISSIONING WORKPLAN One (1) 6-inch extraction well, 22 groundwater monitoring wells, 38 groundwater air sparge wells and 29 vapor extraction wells will be abandoned (see Table 1 for well details). The locations of these wells are shown on Figure 2. Tasks to accomplish the well destructions will include permitting, well abandonment, Site restoration, and site decommissioning reporting. Note: Well MW-06 is a City well and will not be destroyed. 2.1 Task 1 -Permitting Prior to the commencement of the field activities, E2C will obtain well abandonment permits from San Joaquin County Environmental Health Department (SJCEHD) and an encroachment permit from the City of Lodi. The encroachment permit will require preparation of a traffic control plan. 2.1.1 Traffic Control Plan An E2C California Professional Engineer will prepare the traffic control plan in accordance with City of Lodi Engineering Department specifications. 2.2 Task 2 - Well Abandonment A California-licensed C-57 drilling contractor will perform the well abandonment activities in accordance with permitting requirements. The abandonment activities will be overseen by E2C field personnel, under the direction of an E2C California Professional Geologist, or Professional Engineer. E2C Remediation 2