4730 COLBY AVE SEPA 016 - 027 - YMCA Geotech Report 2025-04-14

October 25, 2015 YMCA - Everett L&A Job No. 15-089 Page 8 trenches/galleries by infiltration into this deposit wherever it is encountered by test pits excavated on the site. TEMPORARY DRAINAGE AND EROSION CONTROL Surficial fill, topsoil, and fine-grained soil of the site contain a high percentage of fines which are sensitive to moisture, and can be easily disturbed by construction traffic. A layer of clean, 2-to-4-inch quarry spalls should be placed over areas of frequent traffic, such as the entrance/exit to and off the site, as required, to protect the subgrade soil from disturbance by construction traffic. A silt fence should be installed along the downhill sides of construction area, as required, to minimize transport of sediment onto neighboring properties or streets. The bottom of the filter cloth of the silt fences should be anchored in a trench filled with onsite soil. Spoil soils should be hauled off of the site as soon as possible. Spoil soils and imported structural fill material, if any, to be stock-piled on site should be covered with plastic tarps securely weighted down with sandbags, as required, for protection against erosion. SITE PREPARATION AND GENERAL GRADING Vegetation within construction limits should be cleared and grubbed. Existing fill, topsoil, unsuitable surficial soil should be completely stripped within the building pad of the multi- use building. Existing structures to be demolished should also have their foundations removed. The exposed soils after stripping should be thoroughly compacted to a non- LIU & ASSOCIATES, INC.