WORK PLANS - Laserfiche WebLink

Home Browse Search

enabling a phase transfer of hydrocarbons from a dissolved state to a vapor phase. The air is then vented through the unsaturated zone. When air sparging is combined with SVE, the SVE system creates a negative pressure in the unsaturated zone through a series of extraction wells to capture the �j diffusive vapor plume. SV is also used to remediate petroleum hydrocarbons located in the vadose zone. . Seven new air-sparge wells (AS-2 through AS-8) are proposed to be installed to the north, south and west of existing air-sparge well (AS-1), in the general vicinity west of the former UST and current aboveground storage tanks and fuel islands (Figure 2). Three new vapor extraction wells (VW-3 through VW-5) will be installed to east and south of existing SVE wells (VW-1 and VW-2), in the northwestern corner of the Site. Placement of both the AS and SVE wells is based upon results of the vapor extraction pilot test performed in 1996 and recommendations made in the 2010 Pilot Test Report prepared by AMSC. A schematic flow diagram for the AS/SVE Treatment system is presented on Figure 7. The salient components of each element of this system are listed below The proposed AS/SVE system will consist of the following items: • King Buck Technology MultiMode Catalytic Oxidizer Model MMC-5A, trailer-mounted catalytic oxidizer with 100-standard cubic feet per minute (scfm), 5-horsepower (HP) SVE blower and 12- kilowatt electric heater, or engineer's equivalent..However, it is anticipated that granular activated carbon(GAC) will be sufficient to treat the captured vapor concentrations following the initial six to twelve months of sparging. 7.5-HP Ingersoll-Rand rotary screw 28-scfm compressor, �+ 385-gallon polycondensate and knockout water collection tank, • 200-amp distribution panel, Miscellaneous valves,piping and gauges. The SVE and AS system power will be configured in such a way that a SVE system shutdown will also shut off the AS compressor. The AS manifold, trench and well construction detail are shown on Figure 5. The SVE manifold, trench and well construction detail are shown on Figure 6. The location of the AS and SVE wells, trenches and manifolds are shown on Figure 8, along with the projected radius of influence for each of the AS and SVE wells. The blower will be used to induce a vacuum through the soils above the groundwater table (unsaturated soil or vadose zone). Volatile organic compounds (VOCs) in the vapor phase follow the pressure differential created by the applied vacuum through the soil and toward the extraction well points. The extracted air is forced through the knockout tank where moisture is captured. The captured water will be transferred to a polycondensate tank for storage until offsite disposal. The VOC- contaminated air stream is treated by a catalytic oxidizer where the VOCs are destroyed by combustion at a temperature between 550 and 650 degrees Fahrenheit. Once influent vapor concentrations drop below 500 ppmv, GAC treatment may be more cost effective than catalytic oxidation. Stockton Maintenance Station,Task Order No.05 Caltrans Contract No.06A1141,EA 10-ON8300 Project No.S9200-06-05A -6- December 28,2010