6101 23RD DR W NORPRO Geotech Report 2025-07-29

I June 3, 2011 Project No.T-6578 I Surface water must not be allowed to flow uncontrolled over the crest of the site slopes and embankments. I Surface water should be directed away from the slope crests to a point of collection and controlled discharge. If site grades do not allow for directing surface water away from the slopes, then water should be collected and tightlined down the slope face in a controlled manner. I Subsurface IWith paved surfaces extending to the building perimeter and positive drainage away from the building provided, in our opinion installation of customary footing drains at the building perimeter would not be required. 5.8 Utilities 1, Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) or City of Everett specifications. In our opinion, trench backfill could consist of native inorganic granular soils Ithat are placed and compacted structurally as described in Section 5.2 of this report provided the soils moisture content is controlled and will facilitate proper compaction. As noted, based on the condition of the soils at the time of our study, most of the native soils excavated on the site should be suitable for use as backfill during dry Iweather conditions. However, if utility construction takes place during the wet winter months, it may be necessary to import suitable wet weather fill for utility trench backfilling. IThe use of native excavated soils in backfilling of utility trenches must be approved by the public works official. 5.9 Pavements Pavement subgrade should be prepared as described in Section 5.2 of this report. Regardless of the relative I compaction achieved, the subgrade must be firm and relatively unyielding before paving. The subgrade should be proofrolIed with heavy rubber-tired construction equipment such as a loaded 10-yard dump truck to verify this condition. IThe thickness of the various components of the pavement depends not only on the subgrade soils, but also the traffic loading conditions to which the pavement will be subjected. As a commercial warehouse facility, for Idesign, we have assumed the traffic loading can be represented by a design 18-kip equivalent single axle load (ESAL) of 300,000. This ESAL represents traffic loading equivalent of 3 to 18 loaded (80,000 pound gross I vehicle weight) tractor-trailer rigs traversing the pavement daily over a 20-year design life. If heavier traffic loading or volumes are expected,we should reevaluate the following recommended pavement section: I • Three inches of hot mix asphalt (HMA) over six inches of crushed rock base (CRB) or three inches of asphalt-treated base(ATB) The paving materials used should conform to the current Washington State Department of Transportation I (WSDOT)specifications for 'h-inch hot mix asphalt(HMA)surfacing, CRB,and ATB. I Page No. 11 I