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15 June 2009 <br /> AGE-NC Project No.05-1306 <br /> Page 14 of 33 <br /> 5.3.1. Ground Water Extraction System <br /> A submersible water pump was utilized to dewater the over-excavation.The thick slurry of sediment <br /> and ground water caused multiple pump malfunctions.The pump was suspended into a sump created <br /> by the bucket of the excavator and operated intermittently,dewatering approximately 1,000 gallons <br /> of ground water to the primary holding tank of the ground water extraction system. The extracted <br /> ground water was held in a double containment system until a vacuum truck removed the extracted <br /> ground water for proper disposal. <br /> 5.3.2. Ground Water Sampling and Analysis <br /> On 23 September 2005, one water sample was collected from the holding tank by AGE personnel <br /> using a plastic disposable bailer. Additionally,three slurry(soil and water) samples were collected <br /> from the floor of the over-excavation by AGE personnel. Over-excavation samples were collected <br /> from the excavator bucket. Soil sample locations are illustrated on Figure 3. <br /> 5.3.3. Disposal of Extracted Ground Water <br /> I <br /> On 27 September 2005, the extracted ground water was removed by Slaby. Environmental, <br /> l� Incorporated of Borrego Springs, California with a vacuum truck,transported to a permitted waste <br /> disposal facility for disposal. <br /> 5.4. MASSNOLUME CALCULATIONS <br /> The mass of petroleum hydrocarbons removed during over-excavation activities and the mass of <br /> remaining hydrocarbons was determined based on analytical results of soil samples collected during <br /> . the over-excavation and from soil borings advanced during previous site assessment activities. <br /> 5.4.1. Mass of Petroleum Hydrocarbons <br /> Based on analytical results of soil samples collected from soil borings advanced during previous site <br /> assessment activities an estimated 11,301 pounds of TPH-d was present at the site prior to over- <br /> excavation. Closure evaluation of the site conditions developed a re-analysis of the soil data,which <br /> demonstrated a smaller footprint than had previously been developed for the lateral extent of the soil <br /> plume.An estimated 8,819 pounds to 9,594 pounds of TPH-d was removed from the site during soil <br /> over-excavation procedures.A significant portion of the material removed was below the apparent <br /> Advanced GeoEnvironmental,Inc. <br />