4626 HARBOR LN 2018-01-02 MF Import

m m SPECIFICATIONS FOR REINFORCED WALL General 1. The contractor shall have an approved set of plans and specifications on s le al all times during the construction of the wall. The wall layout is the responsibility of the contractor. 2. Nelson Geotechnical Associates (Ni should observe and monitor the construction of the Nall. 3. Straragod geogrid or equivalent shall be used for this project. All geogdd and facing materials shall be approved ty Ni prior to Installation. 4. The contractor may use longer geogrid lengths than the design sections for ease of construction. The geogrid lengths may not be shorter unless approved by the geotechnical engineer. Subgrade Preparation 1. The ground should be prepared by removing surficial organics and loose soil to expose competent native soils as approved by the geotechnical engineer. 2. A generally level bench with a minimum width equal to the design length of the geogrid is required for placement to the reinforced Fill. 3. The excavation shall be cleaned of all excess material and protected. as necessary, from construction traffic to maintain the Intergrity, of the subgrado. 4. The base of the excavation should be deep enough to satisfy a minimum embedment of 1.5 feet. Garland Placement 1. The reinforcement shall be rolled out, cut to length, and laid at the proper elevation, location, and orientation. Orientation of the reinforcement is of extreme Importance since geogrids vary in strength with roll direction. The contractor shall be responsible for the correct orientation. 2. Geogrid shall be placed at the location and elevations shown on the plans. The geogrid length Is measured from the back of the dminagc layer. 3. Prior to placing the fill, the geogrid shall be pulled to remove the slack and stretched by hand until taut and free of wrinkles. Fill Placement 1. Structural fill, consisting of granular Import soils or on-slte material no greater than 3 inches In size. would then be placed upon the subgrade and geogrid. If larger rock is used in the fill, additional layers of geogrid may need to be used In :he reinforcement. The contractor shall prevent damage to the geogrid by placing the first lift of structural fill with at least a 1-foot thickness. The geotochnical engineer shall approve the material placed In the reinforced zone, before placement. 2. Structural fill should have parameters equal to or better than those staled for the reinforced wall fill below with less then 25 percent passing the number 200 sieve. The geolechnical engineer may allow a higher silt content based on review of the wall design and proposed fill parameters. 3. Soil density tests should be penonned as designated by the geotechnical engineer. 4. Fill soils in the wall area shall be compacted to at least 95 percent of Ilia Maximum Dry Density (MDD) as determined by ASTM D-1557. 5. The soil shall be placed In relatively uniform horizontal Ilhs not exceeding 10 or 12 inches in thickness. The lift thickness shall tool exceed the manufacturer's recommended depth for the compactive device used on the project. Drainage 1. A specific drainage system is shown on the plans. Altemative drains can be used based on conditions found in the field and the material used within the reinforced zone. Changes to the drainage system should be approved by the engineer prior to placement. 2. A drainage blanket 12 Inches in width should be Installed directly behind the keystone block facing and shall consist of 2- to 4-Inch rock spalls. All of the drainage materials shall have a fines content no greater than 5 percent passing the number 2W sieve. A flinch rigid perforated pipe embedded in a minimum of one foot of pea gravel or washed rock and wrapped with filter fabric should be installed at the bottom of the drainage blanket 3. Surface water shall not be allowed to pond In or near the reinforced fill zone during or after mristmclion. 4. Suitable clean -outs should be Installed every 50 feel for future maintenance. Design Parameters Reinforced Wall Fill: 32 degrees, 0 PSF, 125 PCF Retained Backfill: 32 degrees, 0 PSF, 125 PCF Foundation Soil: 32 degrees, 0 PSF, 125 PCF External Stability of Wall Minimum Factor of Safety against Base Sliding: 1.5 Minimum Factor of Safety against Overturning: 2.0 Minimum Factor of Safely against Bearing Capacity: 2.0 Internal Stability of Wall Minimum Factor of Safely on Geogrld Strength: 1.5 Minimum Factor of Safety on Geogrid Pullout: 1.5 Soll-Geogrid Interaction Coefficient: 1.0 Percent Coverage of Geogrid: 100 Percent Ins' action 74all wnstruclion shall be periodically inspected under the direction of an engineer registered in the state of Washington with experience in the design of reinforced earth retaining walls. Garage Existing Slab Footing Planter New Sidewalk (optional) Railing Keystone Cap Unit (optional) ` •Cfti " sfted'RbclC Keystone Standard ` 4 21.5-in. Block Bracket m ::• ., •..:• :. Unit Drainage Fill E - ,:.,..:: (3/4" Crushed w Rock or Stone) 03 ` ' ' fj2ih#oroed.Sbil' : _ 18-inch. Min. _ •: embedment c Pin Pile N Finished Grade p ape (211.1 4-inch Perforated PVC Pipe J ` I )nreinforced Concrete -Tightlined to Discharge or crushed Stone Leveling Pad Native Foundation Soil Wall Number of Geogrid Geogrid Height Above Leveling Pad] Geogrid Type Height Geogrid Length (feet) (feel) Layers (feet) 4 2 5.0 0.67 ;i 200 2.67 G 200 0.67 2.67 467 6 3 6.0 G 200 G 2W SG 200 6 4 7.0 0.67 G 20D 2.67 . G 200 4.67 _ (3 20C 6.67 G 200 `Strz (agrid SG 200 (or equivalent) a � m K o on J Q U z U W H 0 W Z O U) J U Z fN W Q u O W to a N f- N 0 J O W l9 N IY W W Z_ l7 Z W 35= vg,3 W Z J o U w Q Z Zi. 2 mi= V a 0 W 13� Z O