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PROBLEM ASSESSMENT REPORT 14800 West Frontage Road Manteca California 5.1.4 Ex-Stu Bioremediation Ex-situ bioremediation consists of excavating the soil and placing it in one or more treatment cells The purpose of the cell is to create an environment to allow for organic constituents to be degraded by indigenous and/or cultured bacteria Creating the environment is achieved by enhancing, maintaining, and monitoring adequate oxygen, pH, moisture, oxygen, and nutrient levels The cell would include a Inver system to contain and prevent migration of constituents The soil would be treated, as it is placed into the treatment cell, with water, nutrients, and cultured aerobic bacteria The aerobic environment and temperature would be maintained in the cell by ether physically working the soil at regular intervals or placing slotted PVC piping horizontally through the soil at various depths The PVC would be marnfolded in two basic sections One section would be connected to the intake and one section connected to the discharge of a blower Monitoring the cell would be done at regular intervals, with nutrient, pH, microbe, and moisture levels adjusted accordingly, utilizing the same PVC manifold system that provides air to the cell To implement such a project, either the site must have sufficient room to build the cell(s) on the surface or a cell can be built in the existing excavation Depending on site-specific conditions, a typical ex-situ bioremediation project will take from 30 to 90 days Once treated the soils may be used to backfill the excavation Soils may also be hauled off site for treatment Soil types, contaminant types, and concentrations must be characterized prior to transport since certain soil types and the presence of certain compounds may preclude acceptance of the soil into an off-site treatment facility 5 1 5 In-Situ Vapor Extraction In-situ soil vapor extraction utilizes a series of vapor extraction wells to remove volatile organic compounds (VOC) from the sod matrix A vacuum is applied to the extraction wells, typically by means of a blower, and VOC vapors contained within soil pore spaces are extracted from the subsurface In-situ vapor extraction can be a time- and cost- effective remedial technology in permeable sod, and if contaminants are volatile at ambient I temperatures Vapor extraction systems have been shown to efficiently remove lighter- chain hydrocarbons from soil Additionally, vapor extraction systems have been shown to have a positive effect on groundwater quality If the vapors brought to the surface are I of sufficient concentration, treatment of the vapors will be required Numerous options are available for treatment of extracted vapors, including thermal destruction, catalytic oxidation, and carbon adsorption The type of vapor treatment is determined by local air discharge regulations, contaminant types, and concentrations I I ' 90-097A PAR 10