1400 W MARINE VIEW DR WATERFRONT PLACE APARTMENTS Geotech Report 2022-10-25

Imported backfill, containing less than 5 percent fines, may be compacted in loose lifts not exceeding • 12 inches depending on the compaction equipment used. Each lift must be compacted prior to placing the subsequent lift. Prior to compaction,the backfill should be moisture conditioned to within 3 percent of the optimum moisture content, if necessary.The backfill should be compacted in accordance with the criteria discussed above. Structural Fill Fill placed to support structures, placed behind retaining structures, and placed below pavements and sidewalks will need to be specified as structural fill as described below: 1. As a minimum, structural fill placed in parking areas, to backfill utility trenches and to support slab-on-grade should meet the criteria for common borrow as described in Section 9-03.14(3) of WSDOT Standard Specifications. Common borrow will be suitable for use as structural fill during dry weather conditions only. If structural fill is placed during wet weather,the structural fill should consist of Mineral Aggregate Type 17 in conformance with City of Seattle Standard Specification 9-03.16 or gravel borrow as described in Section 9-03.14(1) of the WSDOT Standard Specifications, with the additional restriction that the fines content be limited to no more than 5 percent. 2. Structural fill placed as crushed surfacing base course below sidewalks and pavements should meet the requirements of Type 2 aggregate, City of Seattle Standard Specification 9-03.16 or crushed rock base course conforming to Section 9-03.9(3) of the WSDOT Standard Specifications. 3. Structural fill placed immediately outside below-grade and retaining walls (drainage zone) should consist of gravel backfill for walls in conformance with Mineral Aggregate Type 17 (bank run gravel), • City of Seattle Standard Specification 9-03.16, with the exception that the percent passing the U.S. No. 200 sieve is to be less than 3 percent or Section 9-03.12(2) of the WSDOT Standard Specifications. 4. Drain rock placed for footing drains (drainage zone) should consist of Mineral Aggregate Type 22 (3/4-inch crushed gravel) or Type 5 (1-inch washed gravel), City of Seattle Standard Specification 9-03.16, or washed 3/8-inch to No. 8 pea gravel per section 9-03.1(4)C AASHTO Grading No. 8 of the WSDOT Standard Specifications, or conform to Section 9-03.12(4) of the WSDOT Standard Specifications. On-site Soils The on-site soils are moisture-sensitive, generally have natural moisture contents higher than the anticipated optimum moisture content for compaction, and/or are comprised of organic soils. As a result, the on-site soils are not anticipated to be acceptable for use as structural fill.Therefore, imported structural fill meeting the requirements described above should be used where structural fill is necessary. During construction, GeoEngineers can assess on-site materials for use as structural fill, upon request. • GEOENGINEERS_r/ May31,2017 Page 14 File No.22360-003-00