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with an extension (held at the ground surface) will be used to <br /> create a small hole through the underground concrete slab. <br /> After driving the probe through this hole, the gap betwen the <br /> probe and concrete will not be sealed * - <br /> o The drive tip will be driven further by inserting a <br /> narrower pipe or rod into the probe and driving with a sledge <br /> hammer. It will be driven until there is a 3-5 inch clearance <br /> between it and the bottom of the probe. <br /> o The top of the probe will be threaded and capped 3 inches <br /> below grade. It is isolated by the casing and cover. <br /> Pressures will be measured by removing the cover and cap, inserting <br /> flexible tubing into the probe through a plug, and attaching the <br /> tubing to a differential pressure measuring device. When the test <br /> is completed the probes will be removed with a mechanical jacking <br /> device and the holes filled with soil. <br /> Monitoring wells MW-5, MW-6, MW-7, MW-15 and MW-16 (see plate 7) <br /> will also be capped and used to gather additional vacuum data. <br /> Housing of equipment <br /> All equipment (except for the probes) will be contained inside a <br /> lighted block building. This will provide the highest degree of <br /> safety for area residents and ensure quiet operation. <br /> Running the test <br /> The test will be run continuously for 5 - 10 weeks as follows: <br /> o Week 1. The vacuum pump will be started with the air bleed <br /> inlet wide open to ensure the pump is operating smoothly. The <br /> valves will then be throttled to start flow in the vacuum <br /> well. The following will be monitored: <br /> o Flowrate <br /> o Carbon dioxide, oxygen, and hydrocarbon <br /> concentrations in the vent gas. <br /> o Humidity and temperature of vent gas. <br /> o Hydrocarbon concentration in carbon treated gas <br /> and at points within the carbon bed. <br /> o Subsurface vacuums in probes. <br /> o Oil and grease in pump discharge water. <br /> o Weeks 2-10. The flowrate will be adjusted to gather <br /> additional data on how flowrate affects the radius of <br /> influence and biodegradation rate. The same items as above <br /> will be monitored. <br /> * The site investigation showed that very little oil is pooled <br /> above the concrete slab. Perforating the concrete will not <br /> increase the amount of oil on the water table significantly. <br /> 6 <br />