501 RIVERSIDE RD REGIONAL DISPOSAL COMPANY EVT TRANSFER FACILITY PHASE 1 SITE IMP Geotech Report 2025-07-28

RDC EVERETTTRANSFER FACILITY Everett,Washington the asphalt and concrete rubble should be crushed or otherwise ground up and should meet the gradation requirements for gravel borrow as described in Section 9-03.14(1) of the 2012 WSDOT Standard Specifications. If recycled asphalt and/or concrete will be used under pavement areas, we recommend that it meet the gradation requirements for crushed surfacing base course as described in Section 9-03.9(3)of the 2012 WSDOT Standard Specifications. Recycled asphalt and concrete should not be used in landscape areas. REUSE OF ON-SITE SOILS The near surface on-site fill soils consist of sand and gravel that may be suitable for structural fill provided that the soil can be properly moisture conditioned. It may be necessary to import Gravel Borrow to achieve adequate compaction, depending on weather conditions. The existing native alluvial soils should not be planned for reuse as structural fill and should be hauled off-site, unless I used in landscape areas. The contractor should plan to cover and maintain all fill stockpiles with plastic sheeting if the soils will be used as structural fill. The reuse of on-site soils is highly dependent on the skill of the contractor and schedule, and we will work with the design team and contractor to maximize the reuse of on-site soils during the wet and dry seasons(June through September). FILL PLACEMENT AND COMPACTION CRITERIA Structural fill should be mechanically compacted to a firm, non-yielding condition. Structural fill placed as utility trench backfill should be placed in loose lifts not exceeding 12 inches in loose thickness if using hoe-packs or heavy compaction equipment and in lifts not exceeding 4 inches when using hand operated compaction equipment. Base course materials should be compacted in loose lifts not exceeding 6 inches when using heavy drum rollers. The actual thickness will be dependent on the structural fill material used and the type and size of compaction equipment. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts. Structural fill should be compacted to the following criteria: ■ Structural fill placed in utility trenches, should be compacted to at least 90 percent of the MDD estimated in accordance with ASTM D 1557, except that the upper 2 feet of fill below final subgrade should be compacted to at least 95 percent of the MDD, see Figure 3. ■ Structural fill placed as crushed surfacing base course below pavements should be compacted to 95 percent of the MDD. Non-structural fill, such as fill placed in landscape areas, should be compacted to at least 90 percent of the MDD or to the extent possible as approved by the design team. WEATHER CONSIDERATIONS Disturbance of near surface soils should be expected, especially if earthwork is completed during periods of wet weather. During dry weather the soils will: (1) be less susceptible to disturbance, (2) provide better support for construction equipment, and (3) be more likely to meet the required compaction criteria. t I Page 8 June 18,2013 : GeoEngineers,Inc. File No.4322-002-00