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HomeMy WebLinkAboutSPEC_328410_IRRIGATIONTRENCHANDBACKFILL_08272021Project # 21012.00 VANCE THOMPSON VISION BOZEMAN, MT SITE PLAN SUBMISSION IRRIGATION TRENCHING AND BACKFILL 32 84 10 - 1 SECTION 32 84 10 - IRRIGATION TRENCHING AND BACKFILL PART 1 - GENERAL 1.1 RELATED DOCUMENTS A. Drawings and provisions of Contract, including General Conditions and other Division 1 Specification sections, apply to work of this section. 1.2 SUMMARY A. This Section includes the following: 1. Trenching and backfilling for all irrigation system components. 2. Boring under driveways, walks, and curbs. 3. Furnishing and installation of all pipe sleeves. B. Furnishing and installing irrigation system components is specified in Section 32 84 00- Irrigation System of this Specification. 1.3 QUALITY ASSURANCE A. For actual prosecution of the work, use only personnel who are skilled in the work required, familiar with recommended methods of installation, and thoroughly familiar with the requirements of this work. 1.4 UNDERGROUND OBSTRUCTIONS A. The Contractor shall contact all utilities for locations of their installations prior to initiating work. B. The Contractor shall preserve, intact, any underground pipes or other utilities encountered during construction. In case any such utilities or other structures are accidentally broken or damaged, the Proprietor of the underground installation shall be immediately notified, and they shall be immediately replaced in a condition at least equal to that in which they were found, all at the expense of the Contractor. C. Use of Explosives: Use of explosives is not permitted. PART 2 -MATERIALS 2.1 PIPE SLEEVES A. Pipe sleeves shall be Schedule 40 PVC pipe, size as necessary for installation of irrigation system (main line, lateral lines and wiring) as shown on the plans. PART 3 - EXECUTION Project # 21012.00 VANCE THOMPSON VISION BOZEMAN, MT SITE PLAN SUBMISSION IRRIGATION TRENCHING AND BACKFILL 32 84 10 - 2 3.1 SURFACE CONDITIONS A. Inspection: Prior to all work of this section, carefully inspect the installed work of all other trades and verify that all such work is complete to the point where this installation may properly commence. B. Verify that trenching may be completed in accordance with the original design and the referenced standards. C. Discrepancies: In the event of discrepancy, immediately notify the Owner’s Representative. Do not proceed with installation in areas of discrepancy until all discrepancies have been fully resolved. 3.2 TRENCHING/PULLING A. General: 1. All mainlines to be open trenched. All lateral lines can be open trenched or pulled. If Contractor intent is to pull pipe, Contractor shall submit pulling method to the Owner’s Representative prior to commencement of work. 2. Perform all trenching required for the installation of irrigation system components. Make all trenches in accordance with OSHA Requirements with sufficient width to provide free working space at both sides of the trench and around the installed item as required for gluing, joining, backfilling, and compacting while minimizing width of trenches. B. Depth: 1. Trench to sufficient depth to give a minimum of 18 inches of fill above the top of the pipe measured from the adjacent finished grade under driveways and sidewalks. 2. All mainline shall have a minimum cover of 18 inches above the pipe unless as noted below. All laterals shall have a minimum cover of 12 inches above the pipe. 3. All 6” mainline pipe to have a minimum of 36” of fill above the top of the pipe. 4. All 4” mainline pipe to have a minimum of 24” of fill above the top of the pipe. 5. All 3” and smaller mainline pipe to have a minimum of 18” of fill above the top of the pipe. C. Correction of Faulty Grades: Where trench excavation is inadvertently carried below proper elevations, backfill with material approved by the Owner’s Representative and then compact to provide a firm and unyielding subgrade to the approval of the Owner’s Representative and at no additional cost to the Owner. D. Trench Bracing: 1. Properly support all trenches in strict accordance with all pertinent rules and regulations. 2. Brace, sheet, and support trench walls in such a manner that they will be safe and that the ground alongside the excavation will not slide or settle, and that all existing improvements of every kind will be fully protected from damage. 3. In the event of damage to such improvements, immediately make all repairs and replacements necessary to the approval of the Owner’s Representative and at no additional cost to the Owner. 4. Arrange all bracing, sheeting and shoring so as to not place stress on any portion of the completed work until the general construction thereof has proceeded far enough to provide sufficient strength. Project # 21012.00 VANCE THOMPSON VISION BOZEMAN, MT SITE PLAN SUBMISSION IRRIGATION TRENCHING AND BACKFILL 32 84 10 - 3 E. Removal of Trench Bracing: Exercise care in the drawing and removal of sheeting, shoring, bracing, and timbering to prevent collapse or caving of the excavation faces being supported. F. Grading and Stockpiling Trenched Material: Control the stockpiling of trenched material in a manner to prevent water running into the excavations. Do not obstruct surface drainage but provide means whereby storm and waste waters are diverted into existing gutters, other surface drains, or temporary drains. G. Methods: 1. All trench excavation shall be made by open cut. During excavation, material suitable for backfilling shall be piled in an orderly manner a sufficient distance from the banks of the trench to avoid overloading, and to prevent slides or cave-ins. All material not required for backfill or not suitable for backfill, shall be removed from the site by the Contractor. Banks of trenches shall be kept as nearly vertical as possible, and shall be properly sheeted and braced as may be necessary to prevent caving. 2. Trench widths in paved streets or in areas where proximity to other structures require vertical cuts, shall not be wider than is required for proper handling, jointing and bedding of the pipe. 3. The bottom of the trenches shall be accurately graded to line and grade, and provide uniform bearing and support for each section of the pipe on undisturbed soil, at every point along its entire length. Depressions for joints shall be dug after the trench bottom has been graded, and shall be only of such length, depth and width as required for properly making the particular type joint. Care shall be taken not to excavate below the depths indicated. 4. Where rock occurs in trench excavation, the rock shall be removed to a depth of 6 inches (15.2 cm) below the established grade line, and to a width of 12 inches (30.5 cm) greater than the outside diameter of the pipe to be installed in the trench. H. Pavement Removal: 1. Where excavation of trenches requires the removal of asphaltic pavement, the pavement shall be cut in a straight line along the edge of the excavation by use of a concrete saw or similar approved equipment to obtain straight, square and clean break; and, after backfilling and subgrade preparations are completed, hot plant mix asphaltic concrete shall be replaced and compacted. 2. Excess material, including rock, broken concrete, bituminous materials, debris or other materials not suitable for backfill, shall be removed from the site and disposed of by the Contractor. 3.3 BORING A. Locations: Boring shall be used to route pipe, wiring, or both under concrete structures such as walks or curbs where trenching is impractical. Sleeves shall be installed in all bored holes. B. Method: Boring shall be accomplished with a drill, auger, water jet, or any other instrument approved by the Owner’s Representative capable of producing a precise hole. Boring shall not disturb overlaying structures or cause settlement and damage to those structures. Contractor shall submit boring method to the Owner’s Representative for approval prior to commencement of work. 3.4 SLEEVES Project # 21012.00 VANCE THOMPSON VISION BOZEMAN, MT SITE PLAN SUBMISSION IRRIGATION TRENCHING AND BACKFILL 32 84 10 - 4 A. Locations: Sleeves shall be installed wherever routing of a pipe, wiring, or both crosses a paved area or passes through a bored hole. B. Methods: 1. Sleeves laid in open trenches shall be uniformly and evenly supported by undisturbed soil on the trench bottom. Backfill shall conform to standards hereinafter specified. 2. Sleeves installed in borings shall be forced through and shall have a snug fit throughout the length of the bored hole. Sleeves cracked or broken shall not be accepted. 3.5 BACKFILL A. Inspection: The trenching shall not be backfilled until inspection has been completed and the pipe installation, including the grade, alignment and jointing has been found to be in compliance with the requirements of the plans and specifications. B. Around and Over Pipe: 1. Select backfill material consisting of sand, fine gravel or select earth, free of large lumps or rocks larger than 3/4 inch (19 mm) shall be used in backfilling around and over the installed pipe. 2. The select material shall be obtained from the excavation material removed from the trench and shall be processed by screening, sifting, or selective sorting, so as to produce the type of backfill herein specified. The Contractor may at his option and own expense provide an acceptable imported material. 3. Backfill material shall be carefully deposited around and over the pipe in layers not more than 6 inches (15.2 cm) thick, loose measurement, unless otherwise permitted by the Owner’s Representative, wetted to optimum moisture content and uniformly compacted to at least 95 percent of the maximum density obtainable at optimum moisture content as determined by AASHTO T99 Method A or D (latest revision), until the pipe has a cover depth of at least 12 inches (30.5 cm). C. Remainder of Trench Backfill: 1. The remaining depth of the trench shall be backfilled with excavation material removed from the trench, which shall be wetted or dried to near optimum moisture content. 2. Inclusion of a limited amount of stones and rocks will be permitted. Stones and rocks shall in no case be larger than 3/4 inch. The size and amount of rocks used in backfill shall be such that they will not interfere with proper compaction. 3. This material shall be carefully deposited in layers of a thickness suitable to the equipment selected by the Contractor for proper compaction and compacted to at least 95 percent of the maximum density as determined by AASHTO T99 Method A or D (latest revisions). The method of compaction selected by the Contractor shall not cause damage of any nature to the installed pipe. 4. The use of a water puddling of this portion of the trench backfilling may be used if the specified density can be obtained and the backfill material is suitable for this type of trench compaction. 3.6 PAVEMENT REPLACEMENT A. Pavement replacement shall utilize the same materials and design as the original pavement. 3.7 CLEANUP Project # 21012.00 VANCE THOMPSON VISION BOZEMAN, MT SITE PLAN SUBMISSION IRRIGATION TRENCHING AND BACKFILL 32 84 10 - 5 A. Upon completion of the work, the entire site shall be cleared of all debris, and ground surfaces shall be finished to smooth, uniform slopes and shall present a neat and workmanlike appearance. Cleanup shall be considered an incidental item, and no additional payment shall be made for any cleanup item. All fences, culverts, gravel driveways or other obstructions removed or modified during construction, shall be replaced in a condition at least equal to their pre- construction condition, and shall be approved by the Owner’s Representative. 3.8 MAINTENANCE A. The Contractor shall, for a period of one (1) year after completion and final acceptance of the work, maintain and repair any trench or boring settlement which may occur, and shall make suitable repairs to any pavements, sidewalks, or other structures which may become damaged as a result of settlement. All such maintenance and repair shall be at the Contractor's expense. END OF SECTION 32 84 10