5402 25TH AVE W 2016-01-01 MF Import

- ' City of Everett � • • c/o Ron and Kelly Krueger � August 22, 2007 Page 5 Heavy construction equipment should not be operated behind retaining and foundation walis within a distance equal to the height of the wall, unless the walls are designed for the additional lateral pressures resulting from the equipment. Placement and compaction of retaining wall backfill should be accomplished with hand-operated equipment. Retaining Wall Backfill Backfill placed within eighteen (18) inches of any retaining or foundation walis should be free-draining structural fill containing no organics. This backfill should contain no more than five (5) percent siit or clay particles and have no particles greater than four (4) inches in diameter. The percentage of particles passing the No. 4 sieve should be between twenty-five (25) and seventy (70) percent. Due to their high silt content, 'rf the native soils are used as backfill, a drainage composite, such as Mirafi �:nd Enkadrain, should be placed a�ainst the retaining walls. The drainage composites should be hydraulically connected to the foundation drain system. The purpose of these backfill requirements is to assure that the design criteria for the retaining wall is not exceeded because of a build-up of hydrostatic pressure behind the wall. The subsection entitled General Earthwork and SVuctural Fill contains recommendations regardinq placement and compaction of structural fill behind retaining and foundation walls. EXCAVAYION AND SLOPES: The proposed house addition at the southwest corner of the existing residence will not pose a threat to the drainage ravine to the south and southwest. The extremely dense sub-grade soils easily allow for the house addition project. The excavation for the lower level wine cellar does require excavation diligence: two options are provided for owner and contractor choice. Option 1: Offset the excavation a minimum of 3.0 feet from the existing house footing —maintain a 1:1 slope in conjunction with a 5.0 maximum vertical cut. Geotechnical inspections are required. Option 2: Underpin existing house footings with 2-inch diameter pin-piles (see sketch), which would allow for closer excavation to the existing footing. Geotechnical inspections are required. In no case should excavation slopes be greater than the limits specfied in local, state and national government safety regulations. Temporary cuts up to a height of five (5) feet deep in ur.saturated soils may be vertical. For temporary cuts having a height greater than five (5) feet, the cut should h ave an inclination no steeper than 1:1 �L �