Remedial Action Report Construction Phase

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2.2 Adjacent Properties Current uses of the adjacent properties are summarized in the following table. ADJACENT PROPERTIES Land Use Location Relative to Courthouse Square Commercial Bank, parking structure and retail businesses North First Security Bank Northwest First Interstate Bank, a parking lot, apartments and retail businesses West Oddfellows Meeting Hall and the Salem Area Transit office and bus mall South~vest Marion County Courthouse and parking structure South State of Oregon Administrative Services Building Southeast Statesman Joumal Buildin~ East Offices Northeast 2.3 Local Geology and Hydrogeology The subject property is located near the Willamette River flood plain at the southern end of the Eola- Amity Hills, an upland area capped by basalt from the Columbia River Group. The Ella-Amity Hills are part of the western limb of a broad syncline with a north-northeast trending axis. Deformation occurred in pre-Pliocene rocks including those of the Columbia River Basalt and underlying marine sediments. Sediments deposited after the Pliocene, including the Willamette Silt, filled the topographic low~s of the syncline and are not deformed. The post-Pliocene sediments commonly become thinner near the eastern flanks of the Ella-Amity Hills and underlie the subject property to a depth of approximately 150 to 260 feet. Groundwater recharge is primarily by direct infiltration of precipitation which averages approximately 40 inches per year in Salem. Based on previous investigations, the depth to the water table at the site h~s been observed from approximately 10 to 16 feet below street grade. The regional groundwater flow direction appears to be to the northwest toward the Willamette River from the subject property. However, localized variations in the flow direction have been observed. Construction Phase - Remedial Ac[ions - 2- 4080600127 November 9, 1999 Courthouse Square