1010 N BROADWAY EVCC 2018-01-01 MF Import

PROPOSED LIBERTY HALL,EVERETT COMMUNITY COLLEGE Everett,Washington Clearing and Site Preparation Construction of the proposed building will require demolition of the existing motel, parking area, and other appurtenant structures. Concrete and asphalt may be recycled and reused as structural fill in limited areas; otherwise it should be removed from the site along with other construction debris. The recycled concrete and asphalt should be reused as described in the section of this report titled "Reuse of Existing Asphalt, Base and Concrete Rubble." Based on our explorations and site observations, we estimate that the asphalt pavement is 33/2 to 51/2 inches thick. All existing utilities should be removed from the building footprint and rerouted if needed. Existing utility trench backfill under the building footprint should be removed and replaced with structural fill. Areas to be developed or graded should be cleared of surface and subsurface deleterious matter including any debris, shrubs, trees and associated stumps and roots. Graded areas should be stripped of organic soils. Organic soils are likely only associated with the existing landscape areas. - The organic soils can be stockpiled and used later for landscaping purposes or may be spread over disturbed areas following completion of grading. If spread out, the organic strippings should be in a layer less that 1 foot thick, should not be placed on slopes greater than 3H:1V, and should be track-rolled to a uniformly compacted condition. Materials that cannot be used for landscaping or protection of disturbed areas should be removed from the project site. Subgrade Preparation Prior to placing new fills, pavement base course materials or gravel below on-grade floor slabs, subgrade areas should be proof rolled to locate any soft or pumping soils. Prior to proof rolling, all unsuitable soils should be removed from below building areas. Proof rolling can be completed using a piece of heavy tire-mounted equipment such as a loaded dump truck. During wet weather, the exposed subgrade areas should be probed to determine the extent of soft soils. If soft or pumping soils are observed,they should be removed and replaced with structural fill. We recommend that building concrete slabs-on-grade be supported on at least 18 inches of structural fill, consisting of 6 inches of capillary break gravel and 12 inches of imported gravel borrow over a compacted subgrade. Pavement areas should be supported on at least 12 inches of imported structural fill under the crushed rock base course. Recommendations for subgrade preparation under building foundations including overexcavation of silt/clay soils is provided in the foundation support section of this report. If deep pockets of soft or pumping soils are encountered below floorslabs or outside the building footprint, it may be possible to limit the depth of overexcavation by placing a woven geotextile fabric such as Mirafi 500X (or similar material) on the overexcavated subgrade prior to placing structural fill. The geotextile will provide additional support by bridging over the soft material and will help reduce fines contamination into the structural fill. This may be performed under pavement and building floor slab areas depending on actual conditions observed during construction, but it should not occur under future building foundations. • GEOENGINEERS. June 10,2010 Page 5 File No.5836.010-00