1010 N BROADWAY EVCC 2018-01-01 MF Import

PROPOSED LIBERTY HALL,EVERETT COMMUNITY COLLEGE ^^- Everett,Washington Construction Considerations Immediately prior to placing concrete, all debris and loose soils that accumulated in the footing excavations during forming and steel placement must be removed. Debris or loose soils not removed from the footing excavations will result in increased settlement. If wet weather construction is planned, we recommend that all footing subgrades be protected using a lean concrete mud mat. The mud mat should be placed the same day that the footing subgrade is excavated and approved for foundation support. We recommend that all completed footing excavations be observed by a representative of our firm prior to placing mud mat, reinforcing steel,and structural concrete. Our representative will confirm that the bearing surface has been prepared in a manner consistent with our recommendations and that the subsurface conditions are as expected. Deep Foundations Deep foundations may also be considered to support the building,especially if constraints,such as cost or risks associated with potentially contaminated soil disposal, do not allow for partial overexcavation and replacement or installation of drilled aggregate piers. In our opinion, the building may be supported on deep foundations penetrating the compressible silt/clay soils encountered in the borings and bearing in the underlying dense glacial soils. Deep foundations may include drilled shaft, augercast piles, and driven piles (to name a few). In our opinion small diameter steel pipe piles will be the most cost-effective deep foundation system. Our recommendations are discussed below. Driven Steel Pipe Piles In our opinion, 4-inch or 6-inch diameter driven steel pipe piles may be used for support of the building in Zones III and IV, as shown in Figure 3. The pipe pile spacing should be determined by the project structural engineer. The pipe piles should be connected using grade beams. We recommend the 4-inch or 6-inch driven steel pipe piles be installed using a pneumatic impact equipment capable of penetrating a sufficient depth to develop the design loads. McDowell Northwest Pile King of Kent,Washington has equipment capable of installing this type of pile. The pipe piles should be driven a sufficient depth to develop 20 kips and 30 kips allowable capacity (factor of safety of at least 2)for 4-inch and 6-inch diameter piles, respectively. We estimate that the piles will extend about 15 to 25 feet below the bottom of the planned foundations within Zone IV and 10 to 15 feet below the bottom of the planned foundations within Zone Ill. We estimate that total foundation settlements of less than 1/2 inch will develop for properly installed pipe piles. An American Society for Testing and Materials(ASTM) load test is recommended on at least one of the pipe piles within each foundation zone, and no more than 3 percent of piles installed. Lateral loads should be resisted by friction below and passive resistance on the side of the grade beams as described in the Shallow Foundation section above. Small diameter pipe piles should not be designed to carry lateral loads. GEOENGINEERSI June 10,2010 ? Page 15 File No.5836-010.00