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including, but not limited to,air permit requirements,compliance monitoring,system effectiveness,VOC reduction beneath the apartments,adjacent plume control,etc, 3. Installation of vapor points is confusing. The description indicates each vapor point will be installed to 5 feet,subcoatracted to a C-57 licensed drilling company, and hand cored to five feet bgs. Clarification of vapor point installation methodology would be beneficial. 4. The Work Plan describes installation of five vapor point locations to a depth of five feet bgs. Rive soil vapor point locations,with a vapor point installed at 5 feet is insufficient for system and plume monitoring. A sufficient number of vapor monitoring wells.given consideration of lateral and vertical air flow,and soil heterogeneity and plume locations, should be installed to provide evaluation of vapor flow pathways and concentrations between the SVE apartment wells,SVE excavation wells,DPE wells,and impacts to adjacent soil plumes and groundwater plumes. Integration of previously collected soil gas data,such as the Gore-Sorber data for benzene and other VOCs,as reported by Clayton (6 August 2002)should be considered during placement of vapor points. S. As reported for the LAM OU,Parcel 2'1 area,the presence of known and unknown underground lines were confirmed(Sccor,9 January 2004)and subsequently removed (Sector, 10 February 2005). By inference,underground lines are present beneath the aputmernts in the L&M OU, nun-Parcel 2A area as a result of historic operations, including but not limited to the following: a. Underground pipelines to and from the former Standard Oil AM foirnerly located in the area of the northeastern two apartment buildings (Sanborn 1917; Sanborn 1950;Tidewater 1961); b. Underground pipelines to the truck loading rack formerly located in the area of the northeastern apartment building(Tidewater 1961;Sanbom 1977); c. Underground pipelines to and from as least 1Q.AM formerly located to the irnmc&te northeast of the inursection of former Edison Street and Main Street, beneath the apartment building at the same location(Sanborn 2917;Sanbom 1950);and d. Underground pipelines to and from diesel E=k No. 5008 formerly located to the immediate northwest of the intersection of former Harrison Street and Main Street;beneath the apnrtment building as the same location (Sanborn 1950; Tidewater 1961). Placement of vapor probes and air Row pathways should consider the presence of these pipelines,especially as transport conduits for GOntnrninant migration sad SVE short- circuiting. hortcircuiting. 6. Site soils have been described as heterogeneous,these soils"...in the shallow zone predominantly consist(sng)of sats,silty sands,and silty gravels ranging in depths of four to tea feet bgs and organic clays,clays,high permesbility silts,and lenses of sands and poorly graded sands from depths ua&g from four to ten feet bgs" (Secor,29 July 2005, pg.2). As discussed above,vapor point installation sbould consider heterogeneity of soils,and the resultant preferential horizontal pathways(vapor transport)along more permeable soil zones. Ibc.presence of heterogeneous soils supports the need for VOC reduction in conjunction with adequate soilvapox concentration and flow Cwaluation to minimize the potential formigration of adjacent VOCplumes to beneath the apartment buildings. 7. Albeit,construction of SVE wells beneath the apartments is consistent with the objective of removing volatile contaminants from beneath the apartments,the Work Plan does not US Angcles,NCas6 City and San Diego Golden Stzta Envimnmenul l;.i:t.n�t�:_•r.;_5..:�•.�!.'�+N t' 11'ord,!'i�r.1l •�: