WORK PLANS - Laserfiche WebLink

Home Browse Search

Remedial Action Plan RE: 425 W. Larch Street, Tracy, CA October 1 , 2008 W&A Project No. MW08-001 Page 8 of 11 application for electrical service, an application for an air discharge permit, and an application for a building permit would need to be submitted. The typical electrical energy requirements for an SIVE system are single-phase, 230 volt, and 100 amperes service. If SVE were to be implemented, the cost for design, permitting, well installation, construction and installation, operation and maintenance, and continued quarterly monitoring/sampling/reporting is estimated to be approximately $623,500 . 5.4 Groundwater Extraction and Treatment (GET) Groundwater extraction is the process by which groundwater is extracted from one or more wells via submersible or centrifugal pumps. Effective hydrocarbon mass removal via GET is a widely accepted remedial alternative. Extracted groundwater is transported via lateral piping from the extraction wells to a storage tank. The extracted groundwater is then treated using abatement equipment prior to discharge, or is removed and transported off-site for treatment and disposal. Common and cost-effective technologies used in treating extracted groundwater are air stripping and vapor abatement, liquid-phase GAC adsorption, and advanced oxidation process (using UV radiation) . Treated groundwater is discharged either to the sanitary sewer or the storm drain. Given the radius of influence (ROI) (greater than 20 feet) for groundwater drawdown observed during the recent pump test, groundwater extraction and treatment appears to be an implementable alternative at this site. If implemented, a groundwater extraction system would consist of up to two new and three existing extraction wells to maximize influence on the current known extent of impact, with each well extracttmmg approximately 2 to 3 gallons per minute (gpm) . The treatment system will consist of three 1000-pound carbon vessels and associated instrumentation to monitor flow and control performance. Based on discussion with other engineering firms in the area, disposal to the sewer might be possible. Due to well/pump inefficiencies and slow desorption rates inherent to groundwater pump and treat systems, and because groundwater extraction will be slow to mitigate the residual impact adsorbed to the soil matrix, this option, although implementable and viable, may not be the best available alternative for the site at this time. If GET were to be implemented, the cost for design, permitting, well installation, application to the sewer district for discharge, construction and installation, operation and maintenance, and continued quarterly monitoring/sampling/reporting is estimated to be approximately $685 ,300. W&A anticipates that the time required to mitigate impact to near remediation goals using a GET system is approximately 7 years. Post-remedial groundwater monitoring/sampling/ reporting for an additional 3 years after completion of GETS was assumed. 5.5 Dual-Phase Extraction (DPE) DPE technology is designed to target both dissolved- and adsorbed-phase hydrocarbons by simultaneously extracting groundwater and soil vapor from the subsurface. The resultant lowering of the groundwater table exposes additional previously saturated soil to treatment via vapor extraction. In DPE, a high-vacuum blower (liquid-ring pump) is connected to a down-well pipe (stinger) that is installed within a well that has openings only in the lower portion of the well. Once the YW i:.";..ETAE9s aoaaON5OIHcy