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Oaden Environmental Services, Inc. March 4, I988 Mr. William s. Rickman Page 2 (for incinerator pad, spoil pile, etc.) . The approach of the investigation is given below. Methodology Sample Borings Outside of Existing Structures. Subsurface conditions at the site will be explored by drilling and sampling between 12 and 15 borings. We propose to locate the initial borinqs as shown on Plate 1. Additional borings will be completed as needed and as is practical to effectively evaluate the extent of soil contamination. The borings will be advanced with a truck-mounted hollow stem auger drill rig with optional mud capabilities. It is anticipated that the borings may need to be advanced to a depth of 40 feet or greater to determine the vertical extent of contamination. Plate 1 also identifies the type of analyses to be performed on soil samples from the borings (i.e. , chemical, or geotechnical, or both) . Drilling fluids will be used only if borehole caving problems restrict the depth to which borings can be completed, or prevent collecting undis- turbed soil samples. A non-contaminatinq inorganic mud (such as Super Mud^) will be used for this purpose. All mud and soil cuttings generated during the drilling operations will be containerized for offsite disposal at an appropriate facility or for future treatment during remediation activities at the site. Upon termination, the borings will be backfilled with grout using the tremie method or by placement through the hollow stem auger. The grout will consist of a cement-bentonite grout or cement-sand mix. Within the potentially contaminated zone, soil samples will be obtained at 5-foot intervals using a California Liner sampler. Prior to each samplinq attempt, the sampler and sample liners will be steam cleaned. In addition, the augers and drill rods will be steam cleaned between borinqs to reduce the possibility of cross contamination. Recovered samples will be examined in the field and visually classified. Sample Borings Within Existing Structures. To investigate the potential for contamination beneath existing structures, several borings may need to be completed within the boiler house, north of the buried fuel oil tank, and in the processing plant, east of the buried fuel oil tank. Completion of these borings will be dependent on whether or not evidence of contamination is found in borings outside of the existing structure, adjacent to the building. Areas with poor access (such as limited overhead clearance) that w1.11 not. allow the use of a truck-mounted hollow stem auger drill rig are shown on Plate 1. It is expected that one or more borings could be completed within the processing plant with the auger rig at the designated locations.