SITE INFORMATION AND CORRESPONDENCE

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�Kw rF ' Project steps in treatment of the above ground soils will include preparation and submission of a workplan to the San Joaquin Environmental Health Department,site preparation,construction and loading of the soil treatment cells, operation of the treatment cells and backfilling of the soils. It is our understanding that no additional permits are required to treat the soil; however, backfilling of the material will require concurrence V of Public Health Services, Environmental Health Division (PHS/EHD) and the Central Valley Regional Water 1 Quality Control Board (CVRWQCB). f DEFINITION AND REMEDIATION OF GROUNDWATER CONTAMINATION V Manna Pro proposes to advance the definition of the groundwater contamination plume by the installation of additional monitoring wells. The exact number of wells will be determined by results of the upcoming groundwater sampling, coupled with historical data on the extent of the plume. These wells will be used to help define the zero line of the contamination and determine the hydraulic characteristics of the aquifer. All new and existing monitoring wells will be sampled and analyzed for petroleum contamination, including BTEX, TPH-as-gas and TPH-as-diesel iSeveral'of the wells will be used for pump tests to 'determine the actual hydraulic characteristics of the,aquifer. Information gathered.during these tests will be used to ` develop a remedial action plan for submission to the various regulatory agencies. The anticipated remedial action program will consist of extraction wells to obtain hydraulic control of the aquifer., It is anticipated that one pumping well at a flow rate of five gallons per minute will provide adequate hydraulic control at the site. Air stripping,..carbon adsorption or biological treatment will probably be used to treat,the extracted water (if required) prior to discharge. Selection of a final treatment method will be determined by the influent levels encountered,the mixture of volatile/non-volatile hydrocarbons and the final discharge standards.Past experience has shown that air stripping will probably be the most effective option. [ The most probable discharge option is to discharge to the sewer present on site. Exact details of the extraction,treatment and discharge system will be developed when the detailed remedial action plan for the groundwater is prepared. Permitting issues will include obtaining well permits.and discharge approvals, as j well as PHS/EHD approval of the remedial action plan. 1 TREATMENT OF IN-PLACE SOILS + In-situ vapor extraction will be employed to address areas of soil impacted by contamination. Vapor I extraction provides the desorbtion and evaporation of subsurface volatile constituents by circulation air through the affected area. The gases are then collected and treated (if required) prior to discharge. Itis intended that additional field testing will be performed to determine the effectiveness of potential treatment methods for the remaining in- soils.,Soil.venttests Nill_be .conducted and additional soil t borings performed to gather the required data. Utilizing existing information and our previous experience, we estimate that multiple extraction wells will be required. Similar sites have shown that achieving a radius of.influence of 50 feet per well is possible. Information gathered during these tests will be used to develop a remedial action plan for submission to the various regulatory agencies. If (as anticipated) high levels of vapors are removed during the test,-a catalytic oxidation system will ,probably be employed onthe final system to treat vapors prior to discharge. This test data will also be used.for engineering design purposes as well as air pollution permit documentation. QUARTERLY GROUNDWATER MONITORING Quarterly monitoring of the site groundwater will commence with the quarter beginning September 1, 1991 t and ending November 30, 1991. Quarterly reports will be submitted 45 days followng,the close.of the quarter. This monitoring will include a one time redevelopment of all existing monitoring wells, quarterly monitoring of groundwater levels and sampling and analysis of groundwater (for BTEX, TPH-as-gas and - GROUNDWATER EE` TECHNOLOGY, INC.