1125 80TH ST SW 2016-01-01 MF Import

Cornerstone Columbia Dr{ 'opment Co. W-6984 5 July 1990 Page 3 interpretive logs of the explorations are presented in Appendix A The approximate locations of the explorations are indicated on the Site and Exploration Plan, Figure 1. 3.1 Surface Conditions At the time of our exploration program, the undeveloped parcel was thickly covered with surface brush and alder trees. The parcel apparently was logged sometime in the past. Scattered evergreen trees were also observed on the parcel. The topography of the site slopes moderately from south to north, with an elevation of approximately 590 feet at the south and approximately 485 feet at the north. Several scattered areas of debris fill were observed onsite. These random areas of fill appeared to be generally limited to landscaping debris and garbage debris. A series of logging trails traverse the site. Existing fill should be expected in portions of the logging trails where they cross low-lying areas. No surface water was observed onsite at the time of our exploration, although the driving range located west of the site routes their surface water onto the subject parcel. A detention pond from the golf course has an overflow which runs across the northwest corner of the subject property and into a concrete culvert which runs beneath the gravel trail at the north area of the property. During periods of rain, it is likely that substantial runoff from the driving range flows onto the subject property. 3.2 Subsurface Conditions Twelve test pits were excavated across the' parcel. The subsurface conditions encountered at test pit locations were relatively consistent across the site. The surface of the site was mantled with a thin forest duff and topsoil layer of about 112 to 1 foot in thickness. Beneath the surficial topsoil we encountered a loose, moist, tan brown, silty sand with thick roots to a depth of approximately 2 feet. Underlying the loose silty sand, a medium dense, brown, silty gravelly sand (weathered glacial till) was observed. Dense glacial till was disclosed at approximately 3 to 4 feet in depth and observed to the bottom of our test pits. The glacial till was a dense to very dense, moist, gray, silty gravelly sand. The glacial till has been compressed by the considerable weight of glacial ice in the geologic past. Therefore, this till material and all sod units stratigraphically below the till are relatively incompressible and exhibit high shear strength characteristics. In test pit TP-3, we observed fill consisting of loose silty sand with some organics to a depth of