5010 DOVER ST Geotech Report 2025-07-31

August 22nd 2022 G-5756 Ben Erickson Page 6 footing drain system cannot drain by gravity to a discharge location. Installation of clean-outs are recommended to allow periodic maintenance of the drain system. Grading and Earthwork Erosion Control Temporary erosion and sedimentation controls(TESCs), such as silt fences, should be installed down-gradient of the areas to be disturbed to prevent sediment-laden runoff from being discharged off site. Surface runoff should not be allowed to flow over the top of slopes into excavations. During wet weather, exposed soils should be covered with plastic sheeting or straw mulch. Stockpiled soils should be covered with plastic tarps. For permanent erosion control disturbed soils should be landscaped and mulched upon completion of the site work. A construction entrance consisting of 2-to 4-inch size crushed rock should be installed to prevent tracking onto the street. The construction entrance area should be cleared and grubbed prior to rock placement and we recommend underlaying the rock with a woven geotextile such as Mirafi 500X,or equivalent,to provide separation between the rock and subgrade soil. Excavations and Slopes Temporary excavation slopes should not be greater than the limits specified in local, state and federal government safety regulations. We recommend that temporary cuts greater than 4 feet in height be sloped at inclinations up to 1H:1 V(Horizontal: Vertical)in loose to medium dense soils. Temporary excavations in very dense,hardpan soils can be sloped near vertical under the observation of the geotechnical engineer. Permanent cut and fill slopes should be inclined no steeper than 2.5H:1V. Steeper permanent fill slopes can be achieved with the use of geogrid for lateral reinforcement. Slopes that are to be maintained or mowed should be sloped at 3H:1 V, or less. Fill slopes should consist of granular material compacted to a minimum of 90 percent of the material's maximum dry density. If supporting structural elements,the fill should be compacted to the structural fill specification of 92 percent. Based on the subsurface findings, groundwater seepage is not anticipated. If water seepage or other adverse conditions are encountered, excavation should be halted, and the geotechnical engineer should be contacted to review the site conditions. GEO Group Northwest,Inc.