3618 W MUKILTEO BLVD SITE WORK FOR HARBORS EDGE TOWNHOMES 2025-10-27

Geotechnical Engineering Evaluation Mukilteo Boulevard Development Everett, Washington March 31, 2003 NGA File No. 366503 Page 10 moisture may also be necessary. We expect that compaction of the native soils to structural fill specifications would be extremely difficult, if not impossible, during wet weather. Fill Placement: Following subgrade preparation, placement of the structural fill may proceed. All backfilling should be accomplished in uniform lifts up to .10 inches thick, depending on the size of the compaction equipment. Each lift should be spread evenly and be thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas, and within 2 feet of pavement subgrade, should be compacted to a minimum of 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D-1557 Compaction Test procedure. Fills more than 2 feet beneath sidewalks and pavement subgrades should be compacted to at least 90 percent of their maximum dry density. The moisture content of the soils to be compacted should be within about 2 percent of optimum so that a readily-compactable condition exists. It may be necessary, to overexcavate and remove wet soils in cases where drying to a compactable condition is not feasible. All compaction should be accomplished by equipment of a type and size sufficient to attain the desired degree of compaction. Foundations Conventional shallow spread foundations should be placed on undisturbed medium dense or better native soils or be supported on structural fill, rock spalls, or concrete extending to those soils. Where less -dense soils are encountered at footing bearing elevations, the subgrade should be overexcavated to expose suitable bearing soil. The overexcavation maybe filled with structural fill, rock spalls, or the footing may be extended to the bearing native soils. If footings are supported on structural fill or rock spalls, the fill zone should extend outside both edges of the footing a distance equal to one-half of the depth of overexcavation below the finished subgrade. Both perimeter and interior footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost protection and bearing capacity considerations. Minimum foundation widths of 16 and 24 inches should be used for continuous and isolated spread footings, respectively for footings supporting two stories or less. For footings supporting three stories, minimum foundation widths of 18 and 24 inches should be used for continuous and isolated footings, respectively. Standing water should NELSON GEOTECHNICAL ASSOCIATES, INC. EXHIBIT #10 PArF /.?nF Z4