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

Y • October 25, 2015 YMCA - Everett L&A Job No. 15-089 Page 9 yielding state with a vibratory compactor and proof-rolled with a piece of heavy earthwork equipment. EXCAVATION AND FILL SLOPES Under no circumstance should excavation slopes be steeper than the limits specified by local, state and federal safety regulations if workers have to perform construction work in excavated areas. Unsupported temporary cuts greater than 4 feet in height should be no steeper than 1 H:I V in fill, topsoil, weathered soil, and no steeper than 3/4H:1 V in advance outwash and till-like soils. Permanent cut banks should be no steeper than 2-1/4H:1 V. The stability of cut slopes should be observed and verified by a geotechnical engineer during excavation. Permanent fill embankments required to support structural load should be constructed with compacted structural fill placed over proof-rolled, undisturbed, silty sand deposits after the unsuitable surficial soils are stripped. The slope of permanent fill embankments should be no steeper than 2-1/2H:1 V. Upon completion, the sloping face of temporary and permanent cut banks and 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 is encountered, the excavation work should be immediately halted and the slope stability re-evaluated. The slopes may have to be flattened and other measures taken to stabilize the slopes. Stormwater should not be allowed to flow uncontrolled over cut and fill slopes. Permanent LIU & ASSOCIATES, INC.