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GEOMATRfX In addition, bulk dredge samples need to be collected for analysis of acid generation potential, ' which will be done by McClelland, a laboratory that specializes in analysis of acid generation/ neutralization potential. The Port will provide Geomatrix with certified laboratory analytical results of the sediments. Geomatrix will statistically evaluate the analytical results for comparison with previous ' maintenance dredging core samples and dredging material samples. The deliverable for this task will be a letter-report describing the results and statistical comparisons. 2.3 TASK 3: EVALUATION OF VADOSE ZONE ' This task will provide the background data needed to assess the existing conditions in the vadose zone beneath the DPS, which will subsequently be used to address the DPS's attenuative capacity. The 40-acre disposal site was previously characterized as suitable for placement of dredged material. In the fall of 2001, approximately 65,000 cubic yards of dredged material were applied to the DPS. The dredged material was characterized prior to beginning activities and ' found to have only slightly elevated concentrations of lead, barium, copper, and zinc. To be consistent with previous investigations at the DPS, soil samples will be collected from three depths at five locations across the site. At each location, samples will be collected from depths of 1, 2, and 4 feet below ground surface and will be analyzed for pH, lead., barium, copper, and zinc. Samples will be collected using a hand auger or drive sampling device. In addition to the borings on the DPS, five soil borings will be drilled in the overflow area ' north of the Roberts Island DPS as shown on Figure 1. Each boring will be advanced, using a hollow-stem auger rig, until the boring reaches the water table (estimated to be within about 10 feet of the surface). Continuous core samples will be taken using a sleeved, split-spoon sampler. Samples will be collected where significant breaks in lithology are noted. It is estimated that three samples per boring will be submitted for physical analysis (grain size and permeability), and four samples per boring will be submitted for chemical analysis (pH, cation exchange capacity, and organic carbon content). In addition, bulk sediment samples will be ' collected for analysis of acid generation potential. These samples will be submitted to McClelland. The deliverable for this task will be boring logs detailing the lithology of each boring and tables of the physical and chemical analyses for each sample. ' I:\PROJECn6000s\6988.000\6988-IO.doc 3