Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
r <br /> A.Teichert&Son Inc.Mobile Equipment Shop 103 N.'E'St.Stockton,CA. <br /> Remedial Action Plan March, 1994 <br /> N� 22.2 MW-14 Well Construction <br /> Four-inch diameter well MW-14 was constructed in the soil boring on March 10 and 11, <br /> 1994. The well is constructed of schedule #40 PVC well riser pipe and 0.020-inch <br /> machine--slotted well screen. The well screen extends from a screw-on cap at total depth <br /> to 55 feet bgs. Blank riser pipe extends from 55 feet bgs to surface. The screened interval <br /> is surrounded by a filter pack of #3 Lonestar sand, extending from total depth to 51 feet <br /> bgs. Subsequent to filter pack emplacement through the augers, the well was developed <br /> by the surge and bail method. Approximately 60 gallons of water was produced during <br /> development. Bail down recovery data was not recorded as well drawdown was negligible <br /> and recharge was rapid. The filter pack was segregated from grout sanitary seal by three <br /> feet of hydrated bentonite pellets. The pressure-emplacement of neat cement/bentonite <br /> grout from 49 feet bgs to grade was observed by San Joaquin County Department of <br /> Environmental Health personnel. A traffic rated 30-inch square vault was emplaced over <br /> the well head. The well vault finish design, including establishing integrity of the grout well <br /> seal and vault concrete, was being finalized at the time of this report preparation. The well <br /> head will be completed during SVE system construction. <br /> 2.3 Pilot Test Results <br /> The newly constructed well was evaluated for soil vapor extraction feasibility during a four- <br /> hour test. The test utilized a 4 v2 horsepower regenerative ring compressor (blower) <br /> rated at 206 CFM. Manometer gauges were utilized to measure vacuum inches of water <br /> column gauge (WC) on wells MW-3, 9, 10, and MW-11. Wells MW-12 and MW-13 were <br /> not evaluated because the screened intervals were below the water table. An initial <br /> vacuum of 20 WC was generated to start the test (lowest flow/vacuum possible, this was <br /> done with the system in full bypass mode). The initial flow induced measurable vacuum <br /> on the four surrounding wells. The well head vacuum was increased in 10 WC increments <br /> to 50 WC Based upon the low CFM flows generated, the vacuum system was opened to <br /> full flow. A maximum of approximately 36 CFM was generated with an attendant vacuum <br /> of 98 WC. This flow rate generated vacuums exceeding -0.25 WC (gauge, manometer), <br /> in wells MW-3, 9, 10 and MWA 1. Field hydrocarbon measurements of the test airstream <br /> were not realized as the airstream from the subsurface caused the flame ionization <br /> detector in the organic vapor analyzer to flame out. An oxygen content of 3% was <br /> measured by catalytic explosimeter during the test. Field notes documenting site work and <br /> calculations of field measurements and engineering units are included in Appendix D. <br /> The vacuum/flow data suggests soil vapor extraction is feasible, albeit with high vacuums <br /> and relatively low flow rates. A radius of influence exceeding -0.25 WC was generated <br /> extending to well MW-9, located approximately 80 feet to the west. The radius of influence <br /> is illustrated in Figure 6. A curve of flow and vacuum (blower curve) and a plot of vacuum <br /> and distance from source is illustrated in Figure 7. <br /> 5 <br /> 1► <br />