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EM 1110-1-4001 <br /> 3 Jun 02 <br /> • After evaluating the historical data and estimating time scales, a Work Plan should be prepared for the <br /> performance of the rebound test A well thought out and well written Work Plan as described in <br /> Paragraph 4-4 of the Manual is a key element in the success of the test Just as important is the <br /> communication of the Work Plan to field personnel <br /> The first step in preparing the Work Plan is to set objectives For rebound testing,the primary objectives <br /> are to measure the residual vapor concentrations to low permeability soils and to identify locations with <br /> high residual concentrations With these data and estimates for the contaminated volume,the total <br /> residual mass in the site subsurface can be evaluated If the residual mass is relatively low the site can be <br /> closed If cleanup goals have not been met then future system operation can be optimized to meet the <br /> goals <br /> The following list of tasks summarizes the planning stage of a rebound test <br /> 1 Compile historical data <br /> a Extraction rate history <br /> b Extracted vapor concentration history <br /> c Monitoring point vapor concentration history <br /> 2 Evaluate characterization and historical data <br /> a Is the site sufficiently characterized to estimate the degree of heterogeneity and the <br /> contaminated volume? <br /> b Estimate representative contaminated volume <br /> • c Estimate overall mass transfer coefficient <br /> d Is a rebound test useful at this point? Is the extracted concentration low and slowly <br /> decaymg9 <br /> 3 Set objectives for the effort <br /> a Estimate residual mass <br /> b Locate residual mass <br /> c Estimate duration of operation to meet cleanup goals (or provide data for risk assessment <br /> modeling to close the site) <br /> 4 Specify parameters for measurement and sampling frequencies <br /> a Vapor concentrations in extraction wells prior to the start of the rebound test <br /> b Vapor concentration decay in extraction wells <br /> c Extraction rates <br /> 5 Prepare the Work Plan <br /> F-4 Field Procedures <br /> The execution of a rebound test occurs in three phases (1) steady operation and monitoring of the SVE <br /> system,(2)shutdown for a period of dormancy, and(3) re-start of the SVE system The extraction <br /> period leading up to the rebound test should be performed with as few disruptions as possible At sites <br /> with multiple extraction wells, different extraction strategies are often employed to maximize <br /> contaminant recovery and to avoid stagnation zones In the period leading up to the rebound test, a <br /> single extraction configuration should be employed to avoid complexities in the data interpretation <br /> F-10 <br />