ARCHIVED REPORTS XR0009921 - Laserfiche WebLink

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Corrective Action Plan Page 9 © A small business Russell's FIower Pavilion, operates on the subject property P Unless demolition of the existing structures used by that business is essential to achieve adequate corrective action, the remediation program should be designed so as to cause the least possible disruption to the flower shop business Applicability of Alternate Remedial Technologies The applicability of the following site management and remediation technologies to the site-specific conditions was considered No Active Remedial Action- Management of the site by a continuing program of groundwater-quality monitoring without any active program to remediate the groundwater was considered, but, for the reasons stated below, tins approach was Judged to be insufficient to comply with regulatory requirements The concentrations of components of gasoline that have been detected in groundwater 1 beneath the most severely affected areas of the site are relatively moderate and no floating product has been observed Water-quality analyses have shown samples recovered from the monitoring wells installed around the perimeter of the plume of affected groundwater to be consistently free of contaminants over an extended period The concentrations of components of gasoline in samples from wells in the interior of the plume have exhibited a falling, but somewhat fluctuating, trend since the contamination was first discovered A continued slow reduction in contaminant concentrations can be expected in the future due to natural biodegradation of hydrocarbons into carbon dioxide and water by the activity of indigenous biota Although the site investigation and groundwater-quality monitoring program completed to date indicates that hydrocarbon concentrations are slowly declining and there is no rapid spreading of the contaminant plume, the concentrations of some of the contaminants of primary concern (i a benzene, toluene, ethyl benzene and total xylenes) in the most severely affected zone of the subsurface (i a in the vicinity of monitoring wells NAV 3, NAV 4 and ULT 9 - see Figure 2 for locations) remain relatively elevated Given these circumstances and the relatively high transnussivity of the affected strata, it is expected that a proposal to manage the site by groundwater-quality monitoring alone would not be sufficient to address the concerns of the involved regulatory agencies It is recognized that, although desirable, it may not be possible to eliminate all detectable traces of petroleum hydrocarbons from the groundwater by means of any practicable remediation technology Active remediation may have to be followed by a period of passive groundwater-quality monitoring until such time that natural processes reduce any residual contamination to levels that poses no significant threat to the potential beneficial, uses of the groundwater Fxcavation and Treatirte__nt of Contaminated Soil Where site conditions permit, excavation and treatment of contaminated soil is a cost effective method for remediation