SITE INFORMATION AND CORRESPONDENCE

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t ti Soi� R�ediet�en l►1_ ta�net',�ytg6 saeh of the 5 soil re-mediation alternatives have+ been compared and ranked against one another for each of the nine qualifying criterion. Alternatives are given 1 - 3 prints based upon their ability to most criteria objectivcr. One point is given for alternatives tlsat meet criteria least effectivdly, three points ! given for alternatives that meet criteria most effectively. The relative rankings are shown on Table 2 along with n Cumulati'/e "score" for each approach. The scoring rationale for each criterion sa discussed below. Criterion 1.: The excavation approaches (1 and 2) provido a lower level of protection for human health arA the environment and also represent a potential threat of further groundwater contz:mAnstion since the majority of soil hydrocarbons are at the capillary fringe. Generally the prrcass of excavation AA8,11ts in Truman exposure to hydrocarbon compounds due to direct volatilization ani contact with soils and dist. in situ removal .f hydrocarbons from the affected soil area using vapor extraction tez-hniyues or bioremediation (3 and 5) would have a slightly higher level of protection for the -environment. Neither of these twchniques 1 exposes humans to direct volitization of hydrocarbon3 however both � of these approaches are limited by the extremely low soil permeability to both vapor and water. Capping of tho soils with ++ los pornwabili`y cover is an affective mothod for limiting the i ly migration of hydrocarbons in the underlying soils. if p atururaall maintained the cap would isolate the impacted soils and natural chsmic•sl and biologic degradation processes would further mitigate the potential impauts. Criterion 2. Alternatives 1, 3, and 5 will each result in reduction of the toxicity, mobility and volume of contaminants although, as mention above in-situ treatment will have limited efficacy. Altftrr.utives 2 and 4 would both reduce mobil:'ty but would z-oly on nature: degradation processor to reduce contamisiant toxicity and volume. Criterion 3. : All five approaches can be implemented within regulatory guidelines. Criterion 4. : Conservative estimates for both capital and oper-ating costs for sail remediation indicate that excavation would be the most costly of these alternatives. This dvas not include t certain costa associated with excavation which are Presently unknown including, the lose of use, the cost of removing and , temporarily storing clean soil which is removed, and the threat to the structural integrity of buildings on-site. in-situ treatment methods due to permeability limitAtions would be more costly than E a capping approach. F 3 "c.4o3.WF