1010 N BROADWAY EVCC 2018-01-01 MF Import

PROPOSED LIBERTY HALL,EVERETT COMMUNITY COLLEGE Everett,Washington After completing the proof rolling, the subgrade areas should be recompacted to a firm and unyielding condition, if possible. The achievable degree of compaction will depend on when construction is performed. If the work is performed during dry weather conditions, we recommend that all subgrade areas be recompacted to at least 95 percent of the maximum dry density(MDD) in accordance with the American Society for Testing and Materials (ASTM) D 1557 test procedure (modified Proctor). If the work is performed during wet weather conditions, it may not be possible to recompact the subgrade to 95 percent of the MDD. In this case, we recommend that the subgrade be compacted to the extent possible without causing undue weaving or pumping of the subgrade soils. Subgrade disturbance or deterioration could occur if the subgrade is wet and cannot be dried. If the subgrade deteriorates during proof rolling or compaction, it may become necessary to modify the proof rolling or compaction criteria or methods. Subgrade Protection Site soils contain significant fines content(silt/clay) and will be highly sensitive and susceptible to moisture and equipment loads. If the existing pavement is removed, the exposed subgrade soils can deteriorate rapidly in wet weather and under equipment loads. The contractor should take necessary measures to prevent site subgrade soils from becoming disturbed or unstable. Construction traffic during the wet season should be restricted to specific areas of the site, preferably areas that are surfaced with the existing asphalt pavement or working pad materials notsusceptible to wet weather disturbance. The existing asphalt parking lot should be left in place through the winter months, where practical, to limit subgrade disturbance. It may be possible to initially remove only the area of pavement within the building footprint,while leaving the existingpavement around the future building for equipment lay down purposes and for routing equipment. Consideration should be given to removing the remaining asphalt pavement (outside of the building footprint) in dry weather just before final site grading and final paving activities for the project. Protecting the existing soils with a thin layer of crushed rock will not be adequate during the wet season and the subgrade will still deteriorate under equipment loads. If the contractor removes the existing pavement prior to the wet season,consideration should be given to protecting the exposed subgrade areas with asphalt treat base(ATB), or a thicker section of crushed rock or recycled asphalt grindings overlying a geotextile separator. u Structural Fill All fill, whether on-site or imported soil, supporting floor slabs, pavement areas, foundations, or placed against retaining walls or in utility trenches should meet the criteria for structural fill presented below. The suitability of soil for use as structural fill depends on its gradation and moisture content. Materials. Materials used to construct the building pad and surface parking areas and to backfill utility trenches are classified as structural fill for the purpose of this report. Structural fill material quality varies depending upon its use as described below: Page 6.;June 10,2010 ;GeoEngineers,Inc. FUe No.5636-010.00