WORK PLANS_FILE 1 - Laserfiche WebLink

Home Browse Search

1E Ms. Vicki McCartney Project No. 8800401A.0201 ' October 26, 2004 Page 8 FEASIBILITY STUDY ■ An evaluation of remedial alternatives that have a substantial likelihood to achieve cleanup of all impacted soils and/or soils and groundwater. At a minimum, two technologies must be evaluated for implementability, cost and effectiveness. Monitored Natural Attenuation and Degradation Natural attenuation requires no active corrective action, but relies on the natural process of diffusion to reduce hydrocarbon/oxygenate concentrations over time. Natural degradation relies on biological and chemical breakdown of hydrocarbons/oxygenates to reduce concentrations. The existing monitoring and sampling program would be useful in monitoring declining concentration trends. Based on the concentration trend graphs ---� presented in Appendix E, all constituents of concern have declining concentrations .' trends, but the rate of decline of certain constituents indicate that all cleanup goals may not be naturally achieved for up to 20 years. Recent significant declines of certain constituents suggest that cleanup goals may be achieved naturally in a shorter period of time. Cost: Up to.$380,000.00($19,000.00 per year) t Time Frame: Up to 20 years - Advantages: ➢ Low annual cost ➢ Minimal disruption of station operations. ➢ -Does not involve the transport or introduction of contaminants to or from the subsurface. R ➢ Human health and environmental risk is low given that the risk from . concentrations currently present is low. Disadvantages: ➢ Would not actively reduce toxicity, mobility, or volume,.but relies on the natural processes of diffusion and degradation to eventually reduce . these factors. 1 ' P 1 $ T N:IsacDP�20041Pgl88018800401a.4ad.doc Shaw Environmental,Inc. .. i