1228 GRAND AVE Geotech Report 2022-10-25

April 7,2008 Mr.Don Levin L&A Job No. 8A037 Page 14 We recommend that a layer of 4-inch-thick minimum, compacted, crushed rock base (CRB) of 7/8-inch-minus crushed rock, be used for the driveway area. The crushed rock base should be topped with 3-inch-thick Class B asphalt concrete (AC) or 4-inch concrete pavement reinforced with a layer of welded wire fabric at the mid-depth of the pavement. The driveway pavement should be graded to direct storm runoff to flow away from the adjacent steep slope into catch basins installed in the driveway. DRAINAGE CONTROL Building Footprint Excavation Excavation of building footprint of the new residence,if encountering groundwater, should have the bottom of excavation sloped and ditches excavated along the bases of cut banks to direct groundwater seepage to flow into a sump pit from which water can be pumped out of the pit into a nearby storm inlet. A layer of 2-inch crushed rocks should be placed over firm subgrade soils under footings, as required, to protect the soils from disturbance by construction equipment and foot traffic. This crushed rock base should be built to a few inches above groundwater level, but not less than 4 inches thick. The crush rock base should be compacted in 12-inch lifts to a non- yielding state with a vibratory mechanical compactor. Runoff over Impervious Surfaces Storm runoff over impervious surfaces, such as roofs and paved areas, should be collected by underground drain line systems connected to downspouts and by catch basins installed in paved areas. Stormwater thus collected should be tightlined to discharge into a nearby storm sewer. LIU & ASSOCIATES, INC.