9001 AIRPORT RD SNO ISLE SKILL CTR EXPANSION 2009 Geotech Report 2018-01-02 MF Import

I Subsurjace Fxpbiwion. Gcologic Hamrd, and 57w1sle SAi7Is Center A,ididon Preliminary Geaechnica!Engineering Repnn EYercn. Washington PrcliminarY Design Recommtndationa Idensity using ASTM:D 1557 as the standard. If the subgrade contains too much moisture, adequau recompaction may be difficult or impossible to obtain and should probably not be i attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock, quazry spalls, or crushed recycled concrete to act as a capillary break between the new fill and the wet subgrade. Struchual fiU should be placed and compactod within 2 percent of the optimum moisture content. � After compaction of the exposed ground is tested and approved or a free-draining rock course j is laid, possibly in conjunction with engineering stabilization fabric, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the I geotechnical engincer, placed in maximum 12-inch loose lifts, with each lifr being compacted to at least 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standazd. IThe contractor should note that any proposed fill soils should be evaluated by AFSI prior to their use in fills. This would require that we have a sample of the material 72 hours in � advance to perform a Proctor test and determine its field compaction standazd. Soils in which the amount of fine-grained material (smaller than the U.S. No. 200 sieve) is greater t6an I approximately 5 percent (measured on the minus U.S. No. 4 sieve size) should be considered moisture-sensitive. Use of moisture-sensitive soils in structural fills should be limited to favorable dry weather and near-optimum subgrade moisture conditions. I10 2 Suitabiliri of On-Site Soils as Stn:cmral Fill I The on-site lodgement till soils aze suitable for use as structural fill and coa�form to Washington State Department of Transportation (WSDOT) Standazd Specificauon 9-03.14(3) "Common Bonow.' Lodgement till contains significant amounts of silt and are considered moisture-sensitive. Construction equipment traversing the site when the soils aze wet can cause considerable distu�rbance. If fill is placed during wet weather or if proper compaction cannot be obtained due to wet subgrade or soil conditions, a select material consisting of a I clean, free-draining gravel and/or sand should be used. Free�raining fill consisu of non- organic soil with the amount of fine-grained material limited to 5 percent by weight when I measured on the minus U.S. No. 4 sieve fraction and at least 25 percent greater than the No. 4 sieve. Silt Content of On-Site Soil Lahoratory iesting indicates that the native lodgement till contaias elevated silt contents (bet:veen about 40 and 50 percent) and, as such, do not meet WSDOT specifications for use as gravel base, ballast, gravel backfill, pipe bedding, select bottow, or any other application where relatively low silt contents axe required. Materials meeting low sift conunt Irequirements will require that t6ey be imported from an off-site locarion. 17te results of the ( lune!1, 2A08 ASSOCIA7FD F.t9tTHSCIENCES.INC. I EG/Id-EEUBOI/3A3-ProJtar13P0sOL31EEIWP �fl�C 12 �y