4730 COLBY AVE SEPA 016 - 027 - YMCA Geotech Report 2025-04-14

October 25, 2015 YMCA - Everett L&A Job No. 15-089 Page 15 replaced with a structural fill or crushed rock placed and compacted in accordance with the recommendations provided in the STRUCTURAL FILL section of this report. We recommend that a layer of compacted, 5/8-inch crushed rock base (CRB), be placed for the driveway/parking lot. This crushed rock base should be at least 6 inches thick. This crushed rock base should be overlain with a 2-inch asphalt treated base (ATB) topped by a 3-inch-thick Class B asphalt concrete (AC) surficial course in areas of light traffic. In areas of heavy traffic load, such as access by garbage trucks, emergency vehicles, etc., concrete pavement may be used. In these areas, the crushed rock base as described above should be overlain with a minimum 5-inch-thick concrete pavement reinforced with a layer of welded wire fabric or steel rebars placed at its mid-depth. DRAINAGE CONTROL Building Footprint Excavation Footprint excavation for the multi-use building, if encountering groundwater seepage, should have bottom of excavation sloped slightly and ditches excavated along the bases of cut banks to direct collected groundwater into sump pits from which water can be pumped out. A layer of 2-inch crushed rock should be placed over footing bearing subgrade soils, as required, to protect the soils from disturbance by construction traffic. This crushed rock base should be built to a few inches above groundwater level, but not less than 6 inches thick. The crush rock base should be compacted in 12-inch lifts to a non-yielding state with a vibratory mechanical compactor. LIU & ASSOCIATES, INC.