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I Harding Lawson Asrxiates <br /> IX RECOMMENDATIONS <br /> HLA makes the following recommendations relative to the first stages of <br /> soil and ground-water remediation: <br /> 1-7 <br /> 1. In order to mitigate further migration of gasoline consituents, we <br /> recommend that 7-Eleven proceed with source control measures in the <br /> ground water. The first step is to authorize HLA to perform a pump- <br /> ing test in the tank backfill at MW-7. On the basis of these results, <br /> we will likely recommend a ground-water extraction system, a French <br /> drain, or combination of both. The water collected should be pro- <br /> oerly disposed or treated on-site. Further evaluation by HLA is <br /> needed to help 7-Eleven evaluate a cost-effective scheme for with- <br /> drawal and disposal. <br /> 2. During excavation for the French drain, soils may be aerated to <br /> remove volatile gasoline constituents. Aeration may be possible at <br /> an adjacent parcel. HLA is prepared to assist 7-Eleven in discus- <br /> sions with the owner of the adjacent parcel and in the development of <br /> a scheme to aerate at the adjacent parcel. Aeration could provide <br /> substantial savings to 7-Eleven because the soil could be reused or <br /> removed to a Class III landfill; disposal at a Class I. or Class II <br /> ic <br /> landfill could therefore be.avoided. <br /> 3. Additional delineation of the plume is. required. Soil borings; . <br /> monitoring wells, .and possibly a soil gas survey may be recommended <br /> at a later time. We believe that 7-Eleven should proceed first with <br /> r_ <br /> the pumping test and the source control remediation described above. <br /> E - <br /> 6i. <br /> s <br /> k <br /> r.! <br /> 15 <br />