Laserfiche WebLink
ll <br /> The -_,radient is pcntle and theretore the Lroundwater flOW dir::ction is Subject to=_hanee dile <br /> !n Minor inlluer:cc•:. sucl as i,lrreased recharne clue to prec'ipturnon or irrigation or iii.:reased <br /> discharge tlue to pumptrw weds. Because of the shallow gradient and relatively low pcmreability <br /> -,edirnentti, an c fraction well -0h a low pumping rate can affect a large area. Based on Brown <br /> and C aldwell`s Qiort-term pumping test, ii is estimated that a pumping rate of at least 1 gallon <br /> per ntirurte cart he sustained in wcil E-1. The capture zone resulting ]torn this pumping will be <br /> a rnaximun, of 120 feet wide (on each side of L"•-1) wid have a staLmation point approximately <br /> 40 feet or less ticmn :!radient of 1;-l. "['hese numbers were calculated using the f()llowing <br /> ecluatiortti frorn Javendcl and "I'sanr_! (1986), <br /> lY = U <br /> 2Ti <br /> and <br /> S = 0 <br /> 2 rzTi <br /> where. <br /> W= width of capture zone measured along a line perpendicular to the gradient at the well <br /> Q = pumping rare = 1 bTm <br /> T = transmissivity = 270 ft'/d <br /> i = gradient = 0.003 (measured as the dominant local gradient near the Station) <br /> S = distance from the pumping well to the stagnation point, measured along the ©ow <br /> direction. <br /> The calculated capture zone produced by pumping well E-1 at 1 &rpm is shown on Figure <br /> 7. The actual capture zone will vary depending on the geology and actual pumping rate. <br /> Extraction wells. ARCO proposes to begin groundwater extraction well E-1 pumping <br /> between 1 and 2 gallons per minute. This pump rate is the maximum that well E-1 can produce <br /> and is limited by the low permeability of the soils beneath the site. The need for additional <br /> extraction wells will be determined by the actual performance of well F-1 and th;:extent of the <br /> hydrocarbon plump as determined by the on-going quarterly monitoring. Well F-1 is plumbed <br /> to the treatment area in the same manner as the vapor extraction wells. <br /> Treatment <br /> Extracted groundwater will be treated by granulated activa!ed arbor. Two carbon vessels <br /> will be located as shown in Figure 3. <br />