Laserfiche WebLink
%0001 %ad <br /> These baseline readings indicated the individual well permeability characteristics and guided the <br /> use of the dilution valve at each well. Wells with> 100" H2O were determined to require opening <br /> of the dilution valve to aid in slurping at lower vacuum pressures. The more permeable wells had <br /> the dilution valves shut completely. <br /> Dynamic Water Level Determination <br /> The authors developed a method for dynamically determining the correct water level without <br /> removing the tubes or disrupting the vacuum. The method requires the use of a triple range <br /> magnehelic gauge setup with quick disconnect couplings to measure the vacuum at the upper and <br /> lower monitoring ports of the wellhead. <br /> The method first requires a measurement of the vacuum at the top sample port. If the well is <br /> properly slurping, the gauge should fluctuate around a range. A typical value would fluctuate <br /> plus or minus 5" H2O at approximately 10" H2O. Then the magnahelic gauges are connected to <br /> the lower sample port. This reading must be lower than the upper port, typically it will be 4" <br /> H2O. If the well is properly slurping,this vacuum should also be fluctuating. <br /> By going from upper to lower ports, one can determine if the slurp tubes are at the correct level. <br /> If the lower port is very low and steady, and the upper port is high and steady, the slurp tube is <br /> in the water. If the upper port is low and steady and the lower port is high and steady, the slurp <br /> tubes are set too high and the well is bioventing. By keeping an eye on the magnahelic gauges and <br /> moving the tube up and down, one can maximize fluctuation. The highest fluctuation is the <br /> dynamic water level and the correct bioslurp level. <br /> Balancing the System <br /> After the slurp tubes were set to the correct water level the wellhead vacuum valves at each well <br /> were opened starting with the well farthest from the system. The wellhead valve was gradually <br /> opened until slurping droplets were observed in the clear section of one inch vacuum hose. This <br /> process continued until all the wellhead valves were open at which point slurping was not <br /> evident in any of the wells. Vacuum readings were then taken at the wellhead and casing. These <br /> readings indicated that the maximum available vacuum the WX system was able to develop with <br /> all the wells open was 11" H2O. This available vacuum was below the minimum required to <br /> effectively slurp from the one inch diameter slurptubes installed in the wells. Therefore, the <br /> system was balanced to slurp from certain wells by selectively reducing the vacuum available to <br /> poor performing wells and directing the additional vacuum to proven slurp wells. <br /> The best bioslurp results were observed when only three to four wells were in operation at one <br /> time. Approximately 30-40 inches H2O was the optimal vacuum pressure needed to maintain <br /> active slurping using existing slurp tubes and current depth to groundwater. The obvious water <br /> and vapor recovery was dubbed "macroslurp" by the field crew due to the readily observable <br /> water trickling through the clear vacuum tube installed at each well. Macroslurp could further be <br /> identified by the sound of running water flowing through the vacuum hose. <br /> 386 <br />