WORK PLANS - Laserfiche WebLink

Home Browse Search

magnitude of 0.003 ft/ft, but the plume has already migrated off site and this method.would-- do nothing to prevent further off-site migration. ♦ Criterion 3: This alternative would not immediately remediate soil or groundwater to levels acceptable to regulatory agencies. Natural degradation of residual hydrocarbons would occur over time. ♦ Criterion 4: _ Additional costs for implementing this alternative arc related to the costs associated with the continued monitoring to ensure natural attenuation is occurring and the permitting and destruction of existing wells at,project completion.. The cost of this alternative is estimated to be about $20,000 per year for monitoring, $15,000- to. .$20,000- for-'enhancing biodegradation with introduction of oxygen if warranted,and$30,000 for a closure plan and well destruction. - E, ♦ Criterion 5: This alternative is effective in 'minimizing the health-based risks in the'short' term. Exposure to humans by contamination releases to the air due to dust,or through ingestion or dermal exposure to impacted soil or groundwater is minimal during groundwater monitoring and well destruction activities but is otherwise nonexistent. ♦ Criterion b: The long term effectiveness of this-alternative is•iiot'acceptable. This alternative would reduce the toxicity and volume of the contaminants in the soil and groundwater by natural biodegradation, but the rate of reduction is not known.' The possibility for health-based risks in the longterm is moderate because contamination has already migrated off site. ♦ Criterion 7: Of all the alternatives the passive remediation approach is the easiest to implement. Groundwater monitoring activities would continue to ensure natural attenuation is occurring. When concentrations have reduced' to levels acceptable to the regulatory agencies or an apparent decreasing trend is evident, a closure plan will be submitted. Well destruction permits would be obtained from the appropriate agencies and the wells would be destroyed by overdrilling the well casing and sand pack and pressure grouting the boring to the surface when concentrations have been reduced to an acceptable level. ♦ Criterion 8: , Since minimal activity would be conducted at the site, the impact on the community would be very minor and not disruptive to the businesses located on the site and nearby. i S A22493\reports\CAP.doc 9