3620 36TH PL NE 2018-01-02 MF Import

GEOTECHNICAL ENGINEERING REPORT PROPOSED COMPOSTING FACILITY SMITH ISLAND SITE EVERETT, WASHINGTON 1.0 INTRODUCTION, 1.1 GENERAL This report presorts the results of our geotechnical engineering services for Cedo; Grove Composting's proposed Smith Island Composting Facility in Everett, Washington. The project site is located on a 25-acre parcel on the north end of Smith Island along Steamboat Slough in Everett, Washington. The subject property lies west of State Route 529 within Section 5, Township 29N, and Range 5E in the State of Washington. The site is shown relative to surrounding physical features on the Vicinity Map, Figure 1, and the Site Plan, Figure 2. 1.2 PROJECT DESCRIPTION We understand that the Cedar Grove Composting Company is proposing to develop a state-of-the-art in -vessel composting facility on the site. As shown on Figure 2, we understand that the proposed facility will include: • Raising site grades by placing structural fill such that the entire site will be graded to about Elevation 8 feet. Cuts on the order of about 4 to 5 feet are planned in the central portion of the site to remove unsuitable materials and establish design grades. The east, north and south sides of the site will require filling to accomplish the site grades. A flood protection berm having a crest width of about 5 to 8 feet and 2H:1V (horizontal:vertical) side slopes will be constructed around the perimeter of the site to about Elevation 11 feet. • Constructing three compost systems, each being about 275 feet (84 m) by 370 feet (112 m) in plan. Compost system Nos. 1 and 2 may be built concurrently daring Phase 1, while compost system No. 3 will be built in the future. Each compost system will consist of 16 compost heap rows that will be mounded on a concrete pad. The heap piles or linear stockpiles will consist of food and yard waste and will be covered with a proprietary fabric using a mobile unwinding machine. The heap stockpiles are planned to range up to 10 feet (3 m) high, and the waste material is anticipated to have a unit weight of approximately 55 to 60 pounds per cubic foot. Short concrete walls are planned between each heap row, and the wall bearing pressure will be about 3,700 pounds per linear foot spread over an 8-foot wide footing. A system of pipes will be installed to facilitate the composting process, including stormwater and leachate collection pipes, and air channels. Two parallel air channels will be constructed under each heap stockpile, and the air channels will extend about 1.2 feet below the top of the concrete pad. The leachate pipes are required to have a minimum slope of 2 percent. In addition, the concrete pads will be sloped at a minimum of 2 percent in the long direction. • Constructing a tipping building and an associated biofrrter in the northeast comer of the site. The tipping building will consist of an approximate 100-foot by 100-foot steel frame structure with a concrete slab on grade. The building will have 10-foot-high, above -grade concrete walls on each end. G e o E n g i n e e r s I File No. 10625-001-01123003