12728 19TH AVE SE BASE FILE Geotech Report 2025-07-29

May 28, 2007 Proposed Office Building L&A Job No. 7A053 Page 8 should be erected along the downhill boundaries of the site to prevent sediment being transported onto adjoining properties or the streets by storm runoff. The bottom of filter fabric of the silt ' fence should be anchored in a trench filled with gravel. EXCAVATION AND FILL SLOPES Under no circumstance should excavation slopes be greater than the limits specified by local, i state and federal safety regulations if workers have to perform construction work in excavated areas. Unsupported temporary cuts more than 4 feet in height should be no steeper than 1 H:1 V in the surficial topsoil and weathered soils, and may be vertical in the underlying very-dense, weakly-cemented, fresh till soils if the overall depth of excavation does not exceed 15 feet. Permanent cut banks should be no steeper than 2H:1 V in the surficial topsoil and weathered soils, and no steeper than 1-1/2H:1V in the underlying very-dense fresh till soils. The soil units into which cut slopes are to be made and the slope stability should be verified by a geotechnical engineer. Permanent fill embankments required to support structural or traffic load should be constructed with compacted structural fill placed over undisturbed, proof-rolled, firm, native, fresh advance outwash soils after the surficial unsuitable soils are completely stripped. Permanent fill to be placed over slopes steeper than 15 percent grade should be retained structurally. The exposed ground exceeding 15 percent grade should be benched with vertical steps not exceeding 4 feet tall after stripping and prior to placing structural fill. The slope of permanent fill embankments should be no steeper than 2H:1 V. Upon completion, the sloping face of permanent fill embankments should be thoroughly compacted to a non-yielding state with a hoe-pack. The above recommended cut and fill slopes are under the assumption that groundwater seepage would not be encountered during construction. If groundwater seepage is encountered, the construction should be immediately halted and the slope stability re-evaluated. The slopes may LIU & ASSOCIATES, INC.