A soil sample was tested to estimate permeability and the radius of influence around the vent well. This information was used to determine vent well spacing and blower size for design of the full-scale bioventing system. To estimate the biodegradation rate of TPH, in situ respirometry testing was performed to measure oxygen uptake in the soil over time. Three monitoring probes were chosen for the tests based on their low oxygen and high TPH concentrations. Soil gas analysis confirmed that the test location was suitable as a pilot site.
Oxygen depletion is consistent with microbial activity in environments rich in organic compounds.
A soil boring was advanced to groundwater level 35 feet south of the test location. Samples also were collected at the background location of 10 feet. An indigenous microbial population lived at the proposed screen interval of 5 to 15 feet, and nitrogen and phosphorous were present at non-limiting concentrations. Moisture in the soil ranged from 2 percent to 14 percent and was somewhat below the typical range of 15 percent to 20 percent targeted for most bioremediation systems. Limited moisture may reduce the efficiency of sandy soil.