ARCHIVED REPORTS_XR0008002 - Laserfiche WebLink

Home Browse Search

hydrocarbons beneath the Site Once the SVE system is restarted, ENSR will collect data to provide a better understanding of the SVE system's effectiveness in remediating the target zone e Are extremely high concentrations of VOCs--at or near explosive limits— present in the extracted gas? No f Do the VOC concentrations in the extracted gas vary significantly over time? Not enough information is available to determine if VOC concentrations vary significantly g Have the total extraction rates failed to reach the expected design rates or are the extraction rates needed for efficient operation? This may be due to poor well installation, improper well design, improper flow balancing or blower design, water table upwelling, or unexpected stratigraphy Consider replacing wells, adding wells, rebalancing the air flows in the system, controlling groundwater levels, or resizing the blower Unknown what design extraction rates were ENSR has proposed the installation of one additional AS well approximately 15 feet east of MW-3 and converting MW-23S into a AS well h Is there evidence that contaminant vapors have escaped containment by the SVE system? A prolonged shutdown of both the SVE system between October 2003 and June 2004 may have resulted in an enlarged plume Since remedial efforts were restarted in September 2004, however, the plume size has reduced significantly i If the SVE and off-gas treatment systems are located outside, are there provisions to drain water lines and sump(s) when the unit is shut down'? The systems are located outside, but this specific question does not apply to this system 8 Alternatives for Possible Cost Savings The contaminant compounds remaining in the vadose soils and/or their concentrations may have changed sufficiently so that other alternatives are more cost effective Consider the following a Has the system reached its cleanup objectives? Determine if the SVE operation is still necessary, or have the concentrations decreased to that the operation can be terminated Can the off-gas treatment system be taken off line due to decreased levels of contaminants in the vapor stream? No, the system has not achieved its cleanup objectives No, the off-gas treatment cannot be taken off-line Extractions wells VEW-2 and MW-19S reporting elevated concentrations in vapor samples collected in September and October 2004 b If the cleanup objectives have not yet been met, can the system be turned off and natural attenuation be allowed to achieve the cleanup objective while remaining protective of human health and the environment? Based on concentrations in groundwater, the operation of the SVE should be re-