1815 13TH ST SEATTLE CHILDRENS NORTH CLINIC 2019-07-08

CENTRAL UTILITY PLANT PARKING LOT Everett,Washington the fill to verify compliance with the compaction specifications, and advise on any modifications to the procedures that may be appropriate for the prevailing conditions. Weather Considerations During wet weather, some of the exposed soils could become muddy and unstable. If so affected, we recommend that: • The ground surface in and around the work area should be sloped so that surface water is directed to a sump or discharge location. The ground surface should be graded such that areas of ponded water do not develop. — ■ Slopes with exposed soils should be covered with plastic sheeting or similar means. • The site soils should not be left uncompacted and exposed to moisture. Sealing the surficial soils by rolling with a smooth-drum roller prior to periods of precipitation will reduce the extent to which these soils become wet or unstable. • Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practicable. Temporary Slopes Temporary slopes may be used around the site to facilitate earthwork construction. We recommend that temporary slopes constructed in the fill and near surface soils be inclined at 11/2H:1V. If temporary slopes are planned in areas where glacially consolidated soils are present, temporary slopes may be inclined at 1H:1V. Flatter slopes may be necessary if seepage is present on the face of the cut slopes or if localized sloughing occurs. For open cuts at the site, we recommend that: • No traffic, construction equipment, stockpiles or building supplies be allowed at the top of the cut slopes within a distance of at least 5 feet from the top of the cut; • Exposed soil along the slope be protected from surface erosion by using waterproof tarps or plastic sheeting; in Construction activities be scheduled so that the length of time the temporary cut is left open is reduced to the extent practicable; ■ Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practicable; • Surface water be diverted away from the slope;and • The general condition of the slopes be observed periodically by the geotechnical engineer to confirm adequate stability. Because the contractor has control of the construction operations, the contractor should be made responsible for the stability of cut slopes, as well as the safety of the excavations. Shoring and temporary slopes must conform to applicable local,state and federal safety regulations. GEOENGINEERIci October 17,2012 Page 7 File No.10738-010-00