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HomeMy WebLinkAboutS-371801GENERAL A. Work shall consist of furnishing and construction of a Keystone Standard Block Retaining Wall System or equivalent in accordance with these specifications and in reasonably close conformity with the lines, grades, and dimensions shown on the plans. B. Work includes preparing foundation soil, furnishing and installing leveling pads, drainage fill and backfill to the lines and grades shown on the construction drawings. C. Work includes furnishing and installing geogrid soil reinforcement of the type, size, location, and lengths designated on the construction drawings. D. Reference: D.R. Strong Consulting Engineers, Civil Sheets C12, C13 & C15. Dated July 15, 2013 SUBMITTALS A. Contractor shall submit certifications with each delivery or shipment of block and grid. QUALITY ASSURANCE A. Owner shall provide soil testing and quality assurance inspection during earthwork and wall construction operations. Owner's quality assurance program does not relieve the contractor of responsibility for wall performance. DELIVERY STORAGE AND HANDLING A. Contractor shall check all materials upon delivery to assure that the proper type, grade, color, and certification has been received. B. Contractor shall protect all materials from damage due to jobsite conditions and in accordance with manufacturer's recommendations. Damaged materials shall not be incorporated into the work. PRODUCTS DEFINITIONS A. Modular Unit: a concrete retaining wall element, machine made from Portland Cement, water, and aggregates. B. Structural Geogrid: a structural element formed by a regular network of integrally connected tensile elements with apertures of sufficient size to allow interlocking with surrounding soil, rock, or earth and function primarily as reinforcement. C. Unit Drainage Fill: drainage aggregate which is placed within and immediately behind the modular concrete units. D. Reinforced Backfill: compacted soil which is placed within the reinforced soil volume as outlined on the plans. MODULAR CONCRETE RETAINING WALL UNITS A. Modular Concrete Units shall conform to the following architectural requirements: face color: concrete gray face finish: tri-plane face configuration bond configuration: running with bonds nominally located at midpoint vertically adjacent units, in both straight and curved alignments. B. Modular concrete materials shall conform to the requirements of ASTM C -1372 Standard Specifications for Segmental Retaining Wall Units. C. Modular concrete units shall conform to the following structural and geometric requirements: compressive strength = 4000 psi minimum absorption = 8% maximum (6% in northwestern states) for standard weight aggregates dimensional tolerances = +1/8" from nominal unit dimensions not including rough split face, +1/16" unit height - top and bottom planes unit size = 100 Ibs/unit minimum for standard weight aggregates inter -unit shear strength = 1500 plf minimum at 2 psi normal pressure geogrid /unit peak connection strength = 1000 plf minimum at 2 psi normal force D. Modular concrete units shall conform to the following constructability requirements: alignment and grid positioning mechanism - fiberglass pins, two per unit minimum horizontal spacing between erected units - 112 inch maximum KEYSTONE BLOCK STANDARD UNIT DETAIL Not - To - Scale zfs 18" u•.; FRONT VIEW P VIEW SHEAR CONNECTORS A. Shear connectors shall be 1/2 inch diameter thermoset isopthalic polyester resin - pultruded fiberglass reinforcement rods or equivalent to provide connection between vertically and horizontally adjacent units. Strength of shear connectors between vertical adjacent units shall be applicable over a design temperature of 10 degrees F to +100 degrees F. B. Shear connectors shall be capable of holding the geogrid in the proper design position during grid pre- tensioning and backfilling. BASE LEVELING PAD MATERIAL A. Material shall consist of a compacted crushed rock base or non - reinforced concrete at the contractors option. UNIT DRAINAGE FILL A. Unit Drainage Fill shall consist of 1 inch "clean' crushed rock meeting the following gradation tested in accordance with ASTM D-422: Sieve Size Percent Passing 1 inch 100 3/4 inch 75-100 No.4 0 -10 No. 50 0 - 5 B. Drainage Fill shall be placed within cores of, between, and behind units a minimum distance of 12 inches as shown on the plans. REINFORCED BACKFILL A. Reinforced Backfill shall be free of debris and generally meet the following gradation tested in accordance with ASTM D -022. Use of backfill that does not conform to this specification must be approved by the Geotechnical Engineer. Sieve Size Percent Pass no 1 1/4 inch 75-100 3/4 inch 75-100 No. 40 0-60 No. 200 0 - 15 (or as approved by engineer) B. The maximum aggregate size shall be limited to 1 1/2 inches unless field tests have been performed to evaluate potential strength reductions to the geogrid design due to damage during construction. C. Unsuitable soils for backfill (high plastic clays or organic soils) shall not be used in the backfill or in the reinforced soil mass. D. Contractor shall submit reinforced fill sample and laboratory test results to the Geotechnical Engineer for approval prior to the use of any reinforced fill material. GEOGRID SOIL REINFORCEMENT A. Geosynthetic reinforcement shall consist of geogrids manufactured specifically for soil reinforcement applications and shall be manufactured from high tenacity polyester yam or high density polyethylene. Polyester geogrid shall be knitted from high tenacity polyester filament yarn with a molecular weight exceeding 25,000 meg /m and a carboxyl end group values less than 30. Polyester geogrid shall be coated with an impregnated PVC coating that resists peeling, cracking, and stripping. B. Manufacturing Quality Control The geogrid manufacturer shall have a manufacturing quality control program that includes QC testing by an independent laboratory. The QC testing shall include: Tensile Strength Testing Melt Flow Index (HDPE) Molecular Weight (Polyester) DRAINAGE PIPE A. If required, the drainage pipe shall be perforated pipe manufactured in accordance with ASTM D -3034, per the contract plans. EXECUTION EXCAVATION A. Contractor shall excavate to the lines and grades shown on the construction drawings. The Geotechnical Engineer shall observe the excavation and provide approval prior to placement of leveling material or fill soils. Proof roll foundation area as recommended by the Geotechnical Engineer to determine if remedial work is required. BASE LEVELING PAD A. Leveling Pad material shall be placed to the lines and grades shown on the construction drawings, to a minimum thickness of 2 to 4 inches and extended laterally a minimum of 6 inches in front and behind the modular wall unit. B. Soil leveling pad materials shall be compacted until firm and unyielding, as confirmed by the Geotechnical Engineer at time of construction. C. Leveling Pad shall be prepared to insure full contact to the base surface of the concrete units. MODULAR UNIT INSTALLATION A. First course of units shall be placed on the leveling pad at the appropriate line and grade. Alignment and level shall be checked in all directions to insure that all units are in full contact with the base and properly seated. B. Place the front units side -by -side. Layout of corners and curves shall be in accordance with manufacturer's recommendations. C. Install shear connectors to achieve wall batter per approved plans. D. Maximum stacked vertical height of wall units, prior to unit drainage fill and backfill placement and compaction, shall not exceed three courses. E. Place and compact c ainage fill behind wall units concurrently with placement and compaction of reinforced backfill. STRUCTURAL GEOGRID INSTALLATION A. Geogrid shall be oriented with the highest strength axis perpendicular to the wall alignment. B. Geogrid reinforcement shall be placed at the strengths, lengths, and elevations shown on the Geogrid Reinforced Wall Detail. C. The geogrid shall be laid horizontally on compacted backfill and attached to the modular wall units. Place the next course of modular concrete units over the geogrid. The geogrid shall be pulled taut during backfill placement. D. Geogrid reinforcements shall be continuous throughout their embedment lengths and placed side -by -side to provide 100% coverage at each level. Spliced connections between shorter pieces of geogrid or gaps between adjacent pieces of geogrid are not permitted. REINFORCED BACKFILL PLACEMENT A. Reinforced backfill shall be placed, spread, and compacted in such a manner that minimizes the development of slack in the geogrid or installation damage. B. Reinforced backfill shall be placed and compacted in lifts not to exceed 12 inches. Lift thickness shall be decreased, if necessary, to achieve the required density. C. Reinforced backfill shall be compacted to a minimum of 95% of the maximum dry density as determined by ASTM D -1557. The moisture content of the backfill material prior to and during compaction shall be at (or close to) the optimum moisture content. D. Only lightweight hand - operated equipment shall be allowed within 3 feet from the tail of the modular concrete unit. Consolidation of this zone shall be accomplished with two passes of a lightweight plate compactor. No density tests shall be taken in this zone. E. Tracked construction equipment shall not be operated directly upon the geogrid reinforcement. A minimum fill thickness of 6 inches is required prior to operation of tracked vehicles over the geogrid. Tracked vehicle turning should be kept to a minimum to prevent tracks from displacing the fill and damaging the geogrid. F. Rubber tired equipr.:ent may pass over geogrid reinforcement at slow speeds, less than 10 MPH. Sudden braking and sharp turning shall be avoided. G. At the end of each day's operation, the Contractor shall slope the last lift of reinforced backfill away from the wall units to direct runoff away from wall face. The Contractor shall not allow surface runoff from adjacent areas to enter the wall construction site. CAP INSTALLATION A. Cap units shall be glued to underlying units with polyurenthane adhesive. AS -BUILT CONSTRUCTION TOLERANCES A. Vertical Alignment: ±1.5 inches over any 10 foot distance B. Wall Batter: within 2 degrees of design batter C. Horizontal Alignment: ±1.5 inches over any 10 foot distance Corners, Bends, Curves: tt foot to theoretical location D. Horizontal Gap between Erected Units: 1/2 inch maximum E. Installation Location: with 2 inches of staked base location FIELD QUALITY CONTROL A. The wall footings shall be observed by the Geotechnical Engineer on a full time basis. Testing of the compacted backfill shall be performed by the owner at least once every two lifts of backfill placement and compaction. B. As a minimum, quality assurance should include foundation soil inspection, soil and backfill testing, verification of design parameters, and observation of construction for general compliance with design drawings and specifications. GEOGRID & PIN CONNECTION DETAIL Not - To - Scale CONSTRUCTION NOTES 1. Place geogrid on level backfill, extend over fiberglass pins. 2. Place next modular block unit. 3. Pull geogrid taut and place backfill. 4. Stake as required. To Accommodate Drainage To Accommodate Drainage ( Bldgs. M & N) ( Bldgs. M & N) 2 - INCH W -CUT" DRAINAGE (BLDGS. M & N) Not - To - Scale Wood or Chain Link Fence (as Required) Keystone Block (Standard Unit) Wall Height H =I Wall Batter 8' Max, 1H: 8V NOTE: In Lieu of footing drain for wall along east side of Bldgs. M & N, contractor to W -Cut" slots in bottom of block to allow drainage. "V -Cut; shall be 4' o.c. Geotech to field verify. 12" Maximum P...e .rd Slope Inclination 3 Min. P:a Synteen SF -55 or approved '!c °o alternative` e Unit Drainage Fill 1" Clean �'•o Crushed Rock '.P' (No Fines) Geogrid Length L = H 2' (typical) Structural Fill (Geotech To Confirm) .Geotechnical Engineer , — — — — — — — — must be provided alternative geogrid for approval prior to installation 2' (typical) —_ �•• o'Y• o'p• o'P• o'p• o'Y' Competent /Compacted Subgrade 2'* to 4" Leveling Course GEOGRID REINFORCED WALL DETAIL - BLDGS. M & N (EAST SIDE) Wood or Chain Link Fence (as Required) Keystone Block (Standard Unit) Wall Height H - Wall Batter 8' Ma 1 1 H : 8V Not - To - Scale I .III I 8 0 I m S 3 1 I Min. 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