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Geotechnical Engineering Evaluation NGA File No. 1033518 Larsen Property Garage May 8,2018 Everett,Washington Page 13 Utilities We recommend that underground utilities be bedded with a minimum six inches of pea gravel prior to backfilling the trench with on-site or imported material. Trenches within settlement sensitive areas should be compacted to 95%of the modified proctor as described in the Structural Fill subsection of this report. Trenches located in non-structural areas should be compacted to a minimum 90% of the maximum dry density. Site Drainage Surface Drainage: Final site grades should allow for drainage away from the top of the slopes and away from the planned structure. We suggest that the finished ground be sloped at a minimum gradient of three percent for a distance of at least 10 feet away from the building and top of slopes. Runoff generated on this site should be collected and"routed into a permanent discharge system. This should include all downspouts and footing drains, and runoff generated on all hard surfaces and yards areas. Under no circumstances should water be allowed to flow uncontrolled over the site slopes. Water should not be allowed to collect in any area where footings or slabs are to be constructed. Stormwater handling plans were not developed when this report was prepared and therefore we should be retained to review such plans during final design. Stormwater systems within this site should be designed in accordance with City of Everett regulations. Subsurface Drainage: If groundwater is encountered during construction, we recommend that the contractor slope the bottom of the excavation and collect the water into ditches and small sump pits where the water can be pumped out of the excavation and routed into a suitable outlet. If moisture control is important, we recommend the use of footing drains around the proposed structure. Footing drains, if used, should be installed at least one foot below planned finished floor elevation. The drains should consist of a minimumfour-inch-diameter,rigid, slotted.or perforated,PVC pipe surrounded by free-draining material wrapped in a filter fabric. We recommend that the free-drainingmaterial consist of an 18-inch-wide zone of clean(less than three-percent fines), granular material placed;along the back of walls. Washed rock is an acceptable drain material,or a drainage composite may be used instead. The free-draining material should.:extend up the wall to one foot below the finished surface. ,The top foot of soil should consist of low permeability soil placed over plastic sheeting or building paper to minimize the migration of surface water or silt into the footing drain. Footing drains should discharge into tightlines leading to anappropriate collection and discharge point.with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to wall or footing drains. Under no circumstances should runoff be allowed to flow over the steep slope. NELSON GEOTECHNICAL ASSOCIATES,INC.