11632 EVERGREEN WAY BASE FILE 2018-01-01 MF Import

Proposed Retail Development J-1443 112'"Street and Hwy.99 February 26,2004 � Evcrett,Washington ' Page 12 completely removcd including those azeas extending 10 feet outside the building and any appurtenances. Where peat is left in place, long-term consolidation of the peat should be cxpected. T6e owner should consider the risk of leaving the peat in place outside the building pad. Petroleum-impacted soils may be encountemd during the earthwork-related phases of the project. As noted in the October 2002 Limited P6ase II Environmental Site Assessment report prepared by ZZA, pctroleum concentrations encountered to date are below cleanup Icvels. However, if impacted soils aze encountered, we recommend that representative sample.i be tested to determine if:t is possible to]eave the soils on site. Further envic>nmcntal site characteriza6on is in the plattning stages at this time. The resalts of the study will be presented under separate cover. In general, the project site is underlain by relarively impenneable silty sand (glacial Ull) that is moisture-sensitive. If construction pmceeds during an extended wet weather period and the moisture �ansitive neaz-surface silTy soils arc allowed to inerease in moisture content, they will become , ;-able. In wec conditions, additional soils may need to be removed in otder to achieve the recommended compaction levels. The severity of construction problems will be dependent, in paR, on the precautions that are taken by Uie contractor to protect the subgrade soils. I[ it becomes necessary to overexcavate wet or disturbed soils, it should be confimted through monitoring and tes[ing by a qualified geotechnical engineer. � Following the recommended site stripping and removal of t6e loose undocumented fill soils, unsuitarle fill materials and the peat, and prior to placing any fill over the exposed subgrade, the subgrade should be proofrolfed with heavy rubber-tired construction equipment, such as a fully-loaded tandem-axle dump truck, (in the presence of the geotechnical engineer)to detect soft, yicldin� soils. Areas oF soft and dcflecting soil should be overexcavatcd to a stable subgrade and be replaced with compacted structural fill. Low areas and excavatioiis may tuen be raised to the planncd finished grade with compacted swetural fill. Subg�ade preparation and selection, placement, and compaction of structura[ fill should be performed uttder engineering controlled conditions in accocdance with lhe project spccifications. Once the building pad has been constructcd to grade, the exposed subgrade soils may require p�otection from conscniction trafTic. If necessary, dedicated haul roads across the site, laydown areas, as well as perimeter ruads around the proposed building should be constructed with a minimum oF 12 inches of"select" grunulaz fill, 2- to 4-inch quarry spalls, or crushed recycled concrete of equivalent gradatio�. If wet w•eather constructi�n is undertaken, areas of the building pad with exposed fine-grained soils should be surfaced with"select"ganular fill or&ee- draining crushed ballast or basc �ourse as defined by Sections 9-039(1) and 9-03.9(3), respectively, of the 2004 WSDOT Sta�dard Specificarions manual. T'he surfacing should be , crowned to promotc drainage towazds thc perimeter of the building pad. Material considered to be"sc(ect" should meet the 2004 WSDOT Standazd Specifications Section,9-03.14(1), for Gravel Borrow and have lcss than 5 percent by dry weight passi;,�the U.S.Na 200 sieve. If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to thaw and then be recompacted prior to placing subsequent lifts of structural fill or � �-taa3,ozzeoa : � � ia :