3000 SR 529 2016-01-01 MF Import

January 2B 2010 3 093-93256.100 2.0 SITE DESCRIPTION 2.1 Existing Site Conditions The Smith Island Facihty Sludge Disposal site is located on Smith Island on the north side of ihe main channel o( the Snohomish River, west of State Roule (SR) 529, between the cities of Everett and Marysville. The site is located within a 160-acre parcel owned by M.A.P. p2 LLC (formerly owned by Weyerhaeuser Co ), and wh�le most of the site lies m unincorporated Snohomish County, the eastern portion is located within the Cdy of Everefl A site vicinAy map is shown on the desiqn drawings htled Pacilic Topsoils, Inc., Smifh Isfand Facility, Everetf, Washington, S/udge Disposal A�oa Cap, Desi9n Drawings, January 2070 (Design Drawings). PTI is leasing the Smi�h Island Property from MA P. #2 LLC. The site is approximalely 10 acres in size and was formed by constructing embankments on existing ground lo conlain the spoils from dredging an adjacent process water lagoon. Placement of dredge spoils by the Weyerhaeuser Co. accurred prior to 1971. The former disposal area �as less than one (oot o( topsod above the dredge spods The area is a relafively (lat, closed depression and is currently vegetated with large cottonwood trees and dense brushy undergrowlh. Srormwater runoH irom the site is collected by the ezisting west drainage ditch and conveyed to the west pond. The runoH enters the existing wastewater treatment lagoons located wesl ol the site which are part of an NPDES•permitted treatment system (NPDES permit WA 003197-6) that discharges to Steamboat Slough at the north end of Smith Island through a constructed conveyance system (NPDES Outfall #001). Discharge from this system is allowed only during ebb flow periods of high tide dropping to low tide, and the outlet is constructed m such a way to reduce scour and dissipale energy 2.2 Proposed Construction Activities The project consists of wnstruchng a soil cap over the fortner dredge spod disposal area PTI pians to place an approximate 7-loot thick soil cap over the area. FIII sods for the sod cap will be obtained from 6oth onsite and ottsde sources. The cap surface will siope gently (approzimately 2'%) to the north and south to prowde drainage. 7he runoK from Ihe cap will be collected in penmeler ditches and conveyed to the existing wastewaler treatment lagoons localed west ol the pro�ecl area Uuough the existing west pond and west drainage ddch. The perimeter ditches have a trapezoidal cross•seclion wilh a 4doot botlom wioth and 2-leet depth and 2H�.1V (honzonlal.vertical) side slopes The perimeter ditches will have a 6-inch Ihick topsoil lining and will be revegetated wlth a mizture ot natrve gresses. Beyond Ihe west end ot he soil cap, the discharge ditches (i.e. ihe extension of Ihe penmeter dilches) will have sleeper grades ihan the perimeler dilches; ihey will be lined with a 1-toot- lhick layer of quarry spalls b resist ewsion and will include check dams lo decrease (low velocities. The design details (or the surface water management facililies are shown on the Design Drawings. ai:eiw„is� �o.,o�iwc, �