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q0M <br /> �- 22 November 2006 <br /> E ; <br /> AGE-NC Project No. 95 -0167 <br /> { <br /> Page 9of15 <br /> _ -� 5 .2.2 . FEASIBILITY OF EXCAVATION <br /> Excavation of impacted soil, followed by ex-situ treatment and/or disposal is a very effective method <br /> of remediation. Theoretically, all or at least the majority of the impacted soil is removed. Longer- <br /> chain hydrocarbons are also easily remediated with excavation, where in-situ methods are slower or <br /> ineffective. However, excavation costs can be excessive if the volume of the impacted soil is <br /> significant or if the vertical extent of soil impact exceeds 20-25 feet, resulting in requirements for <br /> r <br /> special equipment or shoring. <br /> ff II As shown on Figure 4, the petroleum hydrocarbon-impacted soil extends beneath the main building <br /> IJ on site and would therefore be inaccessible. Soil boring P7 was advanced under the building and <br /> experienced concentrations of TPH-g at all depths sample (5, 10, and 15 feet) . <br /> — Other potential disadvantages include disruption to a site, air pollution control concerns, backfilling <br /> and compaction costs. <br /> I � <br /> 5 .2. 3 , ESTIMATED COSTS FOR EXCAVATION <br /> At the site, the accessible impacted soil, not soil beneath the building, could be excavated with <br /> traditional equipment. Approximately 775 cubic yards of soil would have to excavated from the <br /> former location of the UST dispenser location. Very little "clean" overburden soil would need to be <br /> removed. <br /> Once excavated, the soil will have to be immediately transferred to an off-site disposal facility. <br /> Space is not available for on-site treatment of excavated soil. Replacement backfill material must <br /> f� be imported if off-site disposal is chosen. The cost for excavation, treatment/disposal andbackfilling <br /> L would likely be between $80. 00 and $ 120.00 per cubic yard, depending upon hydrocarbon <br /> concentrations. Total costs for excavation and treatment or disposal could therefore approach <br /> $ 1005000.00. <br /> ; I <br /> 6.0. GROUND WATER REMEDIATION ALTERNATIVES <br /> AGE believes that in-situ air sparging (IAS) and ground water extraction (pump and treat) are <br /> j 11 appropriate remedial methods to considerto address hydrocarbon4nipacted groundwater onthe site. <br /> II <br /> ; I <br /> i_. <br /> Advanced GeoElvironmental, Inc. <br />