WORK PLANS - Laserfiche WebLink

Home Browse Search

Treatability Study Report and Feasibility Evaluation for In Situ Petroleum Hydrocarbon Remediation Field Maintenance Shop #24, 8020 South Airport Way Stockton, California As is the case with the treatability study implemented for this site, AS is commonly used together with SVE to effect vapor phase removal of contaminants. Through extraction wells, the SVE creates a negative pressure in the unsaturated zone and enhances vapor phase removal. AS technology can also increase dissolved oxygen concentrations in groundwater and promote bioremediation of petroleum hydrocarbons in the saturated zone. Based on investigations performed by previous consultants as well as OTIE, we believe site conditions in the proposed treatability study area are amenable for implementation of AS technology in combination with SVE. 1.3.3. High Vacuum Dual Phase Extraction HVDPE, also known as multi -phase extraction or vacuum -enhanced extraction, is a technology that removes various combinations of contaminated groundwater, petroleum product, and hydrocarbon vapor from the subsurface. Extracted liquids and vapor are collected and treated at the surface prior to discharge. HVDPE can also increase oxygen levels in the hydrocarbon smear zone and can promote/enhance bioremediation. In HVDPE systems for liquid/vapor treatment, a high vacuum system in conjunction with a submersible pump is typically used to enhance liquid and gas extraction from low permeability formations. The vacuum extraction well includes a screened section in the targeted zone of contaminated soils and groundwater. The basic concept of the HVDPE system is to apply a high vacuum to the formation in order to induce fluid (vapor and water) flow. A high -vacuum pump supplies the vacuum to the well, either via direct connection to the casing or to a drop tube. Groundwater flow is produced either by a submersible pump (when vacuum is applied directly to the well casing) or via the drop tube. Based on prior investigation data, we anticipated moderate to high groundwater flow, at depths of up to 60 feet, and the need for a significant amount of air to sustain water lift. As a result, the proposed HVDPE treatability study for the site consisted of a down -well pump for groundwater extraction combined with wellhead vapor extraction at high vacuum. Using the pump to remove groundwater can allow higher vacuum to be applied at the well head and the subsurface since the vacuum is not "lost" through the water -lifting and/or dilution process. Once above ground, the extracted vapors or liquid -phase organics and groundwater are separated and treated. Use of HVDPE has been demonstrated to greatly shorten cleanup times and costs when compared with traditional pump and treat and vapor extraction technologies. OTIE