4937 EVERGREEN WAY QFC FUELING STATION Geotech Report 2023-02-17

Geotechnical Engineering Report 11 January 7,2020 QFC 852 Fuel Station,Everett,Washington RGI Project No.2019-258A building perimeter. In paved locations, a minimum gradient of 1 percent should be provided unless provisions are included for collection and disposal of surface water adjacent to the structure. 5.7.2 INFILTRATION RGI has reviewed the native soil conditions for the potential for infiltration. The native soil is glacially consolidated and it is not efficient for onsite infiltration systems. If an infiltration system has to be used, RGI recommends that the system should have an overflow system. RGI recommends that an allowable infiltration rate of 2 inches per hour be used for system design. 5.8 UTILITIES Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) specifications. For site utilities located within the right-of-ways, bedding and backfill should be completed in accordance with City of Everett specifications. At a minimum, trench backfill should be placed and compacted as structural fill, as described in Section 5.2.4. Where utilities occur below unimproved areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil's maximum density as determined by ASTM D1557. The native soils may be used as backfill provided they can be adequately moisture conditioned and compacted in dry weather condition. Imported structural fill may be required for trench backfill in winter. 5.9 PAVEMENTS Pavement subgrades should be prepared as described in Section 5.2 of this GER and as discussed below. Regardless of the relative compaction achieved, the subgrade must be firm and relatively unyielding before paving. This condition should be verified by proofrolling with heavy construction equipment or hand probe by inspector. With the pavement subgrade prepared as described above, RGI recommends the following pavement sections for parking and drive areas paved with flexible asphalt concrete surfacing. ➢ For heavy truck traffic areas: 4 inches of Hot Mix Asphalt (HMA) over 8 inches of crushed rock base (CRB) over native soil or structural fill ➢ For general parking areas: 3 inches of HMA over 6 inches of CRB over native soil or structural fill The asphalt paving materials used should conform to the Washington State Department of Transportation (WSDOT) specifications for Hot Mix Asphalt Class 1/2 inch and CRB surfacing. ➢ For drive-thru areas: 5 inches of concrete over 4 inches of CRB over native soil or structural fill II 1 Mi �- RILEYGROUP