3000 41ST ST Geotech Report 2025-12-31

PNW Home Builders, LLC ES-2598.03 May 2, 2013 Page 6 Site Preparation and. Earthwork Site preparation activities will likely be limited to those fills needed to establish final grades. We anticipate site preparation will include installing temporary erosion control measures and removing interfering or unwanted vegetation. Temporary Erosion Control We anticipate the primary construction entrance will be near the intersection of 41st Street and The Lowell Riverfront Trail, where new paving areas are likely to be constructed. The section of 41st Street nearest the site is currently paved with asphalt concrete and is within one-half mile of Interstate-5 freeway access. Temporary construction entrances and drive lanes, consisting of at least 12 inches of quarry spalls can be considered in order to minimize off-site soil tracking and to provide a stable access entrance surface. Soil stockpiles should be covered or otherwise protected to reduce soil erosion. Temporary sedimentation ponds or other approaches for controlling surface water runoff should be in place prior to beginning earthwork activities. As observed during our site visit (March 4, 2013), a silt fence has been established around the majority of the site perimeter. Few locations were missing silt fencing but included the southeast`site corner and scattered areas along the north site boundary. A complete silt fence is recommended to be established and maintained around the site perimeter, as practical. In-situ Soils The fill soils indicated in the referenced geotechnical report, and which will likely be exposed during grading, have a high sensitivity to moisture and were generally in a moist to wet condition at the time of the exploration (January 2007) Reported fines contents of the fill soils generally ranged between three to ten percent, with a fines content of 34 percent reported at boring location B-1. Soils with fines contents above five percent,typically degrade rapidly when exposed to excessive moisture. In this respect, the in-situ soils may not be suitable for use as structural fill if the soil moisture content is above the optimum level at the time of construction. In general, soils encountered during site excavations that are excessively over the optimum moisture content will require aeration or treatment prior to placement and compaction. Conversely, soils, that are substantially below the optimum moisture content may require moisture conditioning through the addition of water prior to use as structural fill. If the in-situ soils are determined to not be suitable for use as structural fill, then use of a suitable imported soil may be necessary. In our opinion, a contingency should be included in the project budget for exporting unsuitable soil and importing structural fill. Earth Solutions NW,LLC