1228 GRAND AVE Geotech Report 2022-10-25

April 7,2008 Mr.Don Levin L&A Job No. 8A037 Page 7 SITE PREPARATION AND GENERAL GRADING Site preparation should include clearing and grubbing within construction limits of the new residence. The existing house to be demolished should also have its foundations removed. Surficial topsoil and weak soils in the root zone should be stripped down to dense sand and/or hard silt soil layer within the building pad of the new garage and the new driveway. The exposed soils after stripping should be compacted to a non-yielding state with a mechanical compactor. During construction, one or multiple lines of interceptor trench drains should be installed along the uphill side of the site and behind the crest of the steep slope, as required, to intercept and drain away surface runoff and near-surface groundwater seepage to facilitate grading and foundation construction work. Water collected in such interceptor trench drains should be conveyed into a nearby street side storm inlet. The storm inlet should be covered with a filter sock to prevent sediment from entering the storm sewer system. The filter sock should be cleaned periodically to prevent it from clogging, and should be removed after the construction work is completed. The onsite surficial soils contain a high percentage of fines and are sensitive to moisture. A layer of clean quarry spalls should be placed, as required, over excavated areas and areas of frequent traffic to protect the subgrade soils from disturbance. Silt fences should be erected along the downhill side boundaries of the site to prevent sediment from being transported by storm runoff onto adjoining properties, the street or the adjacent steep slope. The bottom of silt fence filter fabric should be anchored in a trench filled with gravel. EXCAVATION SLOPES Under no circumstance should excavation slopes be greater than the limits specified by local, state and federal safety regulations if workers have to perform construction work in excavated LIU & ASSOCIATES, INC.