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GEOMATRDC 2.4 TASK 4: EVALUATION OF AQUIFER iMonitoring wells that were installed at the Roberts Island DPS in February 2001 will be sampled for water-quality parameters. Prior to collecting samples, the water level will be measured using an electric sounder, and at least four casing volumes of groundwater will be purged from each well using a submersible pump or bailer. During purging, field water-quality parameters (pH, temperature, dissolved oxygen, electrical conductivity, and turbidity) will be measured. Groundwater samples will be collected in laboratory-prepared containers,placed in ice-cooled chests, and delivered to the laboratory under chain-of-custody procedures. Groundwater samples will be submitted for analysis in accordance with the SAP. Four metals have been identified during previous investigation activities as constituents of concern (COCs): lead,barium, copper, and zinc. These metals as well as other inorganic chemicals, will be analyzed as summarized below; however, additional CDCs may be identified during Task 1 that will need to be included in this evaluation. • Dissolved lead,barium, copper, and zinc using EPA Method 6010B. • Inorganic constituents including chloride, sulfate, nitrate as nitrogen, total dissolved ' solids, potassium, bicarbonate, carbonate, sodium, calcium, magnesium, dissolved iron, and dissolved manganese using various EPA methods. Quality assurance/quality control samples will also be collected and submitted to the laboratory for potential analysis, including orie or more equipment blanks, one field blank per day, and one trip blank per sample shipment. All groundwater samples will be placed in laboratory- prepared sample containers and labeled with a unique sample control number, date of ' collection, and project number. A sample control log will be prepared to identify the sample control numbers with the appropriate well number, depth, and other pertinent criteria. Samples will be submitted to the Port's contract laboratory for laboratory analysis. The deliverable for this task will be tables of the analytical data from groundwater samples. 2.5 TASK 5: EVALUATE SITE ATTENUATION POTENTIAL The soil that comprises the DPS will have a certain capacity for attenuation of metals that may leach from the dredged materials. The potential of the soil for attenuation is based on a number of physical and chemical characteristics of the soil including the cation exchange capacity, total ' organic carbon, and texture of the soil. These characteristics will be used to evaluate the attenuation capacity of the soil based on the COCs that may be identified in the dredged ' material. The following section describes our approach to evaluate site attenuation. I:\PROJEC n6000s\6988.000\6988-IO.doc 4