Laserfiche WebLink
SJCEHD may require the evaluation of the lateral extent of impacted groundwater. If the <br /> ' impacted groundwater does not extend off site and repeated groundwater monitoring events <br /> indicate that the impacted groundwater is stable the SJCEHD may consider natural attenuation as <br /> ' a feasible remedial action and not require active groundwater remediation. <br /> To assist with cost analysis, it was assumed that a maximum of six groundwater monitoring <br /> ' wells would be installed to sufficiently evaluate the groundwater conditions. Once the wells <br /> were installed, a quarterly monitoring program would be initiated for a minimum of four <br /> ' quarters. Costs associated with the well installation, groundwater monitoring and reporting for <br /> four quarters is approximately $50,000. <br /> Option 3: Groundwater Investigation and Remediation <br /> ' Following the UST excavation, this option assumes a site investigation would be initiated to <br /> determine the extent of groundwater contamination and to collect hydraulic data, and to evaluate <br /> ' the need for potential remedial options. This phase can potentially be two years in duration, or <br /> more. <br /> A site investigation would include installation of six monitoring wells. After the investigation is <br /> complete, a groundwater remediation system can be designed and installed in approximately six <br /> ' months. Groundwater remedial options include biosparging, a pump and treat system, or natural <br /> attenuation, depending on the investigation results. Installation of groundwater extraction wells <br /> or air sparging wells could be included as part of this remedial option. If there is free-floating <br /> ' product found in the monitoring wells, a separate phase removal element of the system would be <br /> required, but is unlikely. The remediation system would be monitored and reported to the <br /> ' regulatory agency to determine when closure could be attained. The length of time for this phase <br /> depends on the extent of the groundwater impact and if there is a risk to a drinking water source. <br /> ' Costs associated with the permitting and installation of appropriate groundwater monitoring, <br /> extraction or air sparging wells, installation of a groundwater remediation system, groundwater <br /> disposal, and groundwater monitoring and reporting may cost upwards of$500,000. <br /> 1 <br /> ' -0S4CRFP7ICOMMOWacDR70071PR APJ6t6318347601aedoc E-2 <br />