ARCHIVED REPORTS_XR0003169 - Laserfiche WebLink

Home Browse Search

Thes ba is SVE system is composed of a blower or vacuum pump which draws contaminant vapors to one or more extraction wells and then through surface manifold piping, valves, and a vapor- water separator for subsequent delivery to a vapor treatment unit. Vapors may be captured or destroyed using thermal incineration, catalytic oxidation, internal combustion, carbon adsorption, and/or biofiltration. Bioventing employs the SVE system concept to promote the in- situ aerobic biodegradation of hydrocarbon contaminants within vadose soils. This is accomplished by using the SVE mediated movement of air through the area of soil contamination to deliver the large volume of oxygen required to develop and maintain the biomass necessary to accomplish the mineralization (thorough aerobic biodegradation) of fuel hydrocarbons. It has been suggested that using air as a mechanism to deliver oxygen to unsaturated soil could be 1 , 000 times more efficient than transferring it to water (Wilson and Ward, 1986) . A number of sources have reported that analysis of SVE systems indicate that 20-38% of hydrocarbon removal is by biodegradation, with the remainder occurring by volatilization. Nutrients (primarily nitrogen and phosphorus) and moisture may also be added to increase biodegradation rates. The biological destruction component is particularly appropriate to the remediation process when the hydrocarbon contaminant is formed, in part, of compounds that are essentially not volatile. In order to confirm the applicability of SVE to the subject site, it is proposed that an additional well be installed in the immediate area of soil boring EB-11 ( see Figure 2 of text ) . The well will be constructed in the same manner as the previously installed groundwater monitoring wells and will be screened through the area of highest known hydrocarbon contamination ( 15-25 feet below ground surface) so as to permit acquisition of data as to the potential rate of treatment of the 1600-11 , 000 parts per million (ppm) levels of Total Petroleum Hydrocarbons as Gasoline (TPH-G) and 600-2400 ppm Total Petroleum Hydrocarbons as Diesel (TPH-D) detected in soil samples acquired from 15, 20 , and 25 feet bgs during the installation of soil boring EB- 11 . The extraction well will be fitted with the piping, instrumentation, and vacuum pump or blower to induce an air flow of approximately 55-100 cubic feet/minute (CFM) . System piping will be 4" to 6" diameter Schedule 40 PVC. Flow control valves and instrumentation to measure flow, pressure, temperature, and levels of target contaminants will be installed. Pulse venting is expected to enhance vapor removal efficiencies 1 and will be employed by operating wells only periodically in order to allow vapor to diffuse into large areas . Moisture within the extracted air-vapor stream will be removed 9 .