430 Page 299430 BRIDGE END BACKFILL
430.1DESCRIPTION
This work consists of backfilling bridge abutments and sills.
430.2MATERIALS
A.Porous Backfill: The porous backfill material will conform to the requirements of Section 800 with the following modifications: The material will consist of natural sand. Crushed material is not acceptable. The percentage of material passing a #200 sieve will not exceed 2.0%. B.Granular Bridge End Backfill: The granular bridge end backfill material will conform to Section 882. C.Reinforcement Fabric (MSE): The reinforcement fabric will conform to Section 831 (Reinforcement Fabric MSE). D.Drainage Fabric: The drainage fabric will conform to Section 831 (Drainage Fabric-Type B). E.Polyethylene Sheeting: The polyethylene sheeting will be a minimum thickness of 6 mils and will be sufficiently durable so the polyethylene sheeting will not puncture or tear when installed as intended. F.Drainage Tubing: The drainage tubing will be corrugated polyethylene drainage tubing conforming to Section 990. G.Black Steel Pipe: The black steel pipe will conform to ASTM A53. H.Vertical Composite Drain: The vertical composite drain will be a geocomposite sheet drain material consisting of a drainage core with a subsurface drainage geotextile attached to or encapsulating the core. Include all necessary fittings and material to splice one sheet, panel, or roll to the next. The drainage core will be of a material using long chain synthetic polymers composed of at least 85% by mass of polypropylene, polyester, polyamide, polyvinyl chloride, polyolefin, or polystyrene. The core will be fabricated in sheets, panels, or rolls of adequate strength to resist installation stresses and long-term loading conditions. The core will be built up in thickness by means of columns, cones, nubs, cusps, meshes, stiff filaments, or other approved configurations. The geocomposite sheet drain will have a minimum compressive strength of 40 psi when tested in accordance with ASTM D1621 Procedure A. Splices, fittings, and connections will be of sufficient strength to maintain the integrity of the system during construction handling and under permanent loading without impeding flow or damage to the core. The geocomposite drain material will be covered with an opaque, ultraviolet resistant waterproof covering during storage. The maximum allowable exposure to ultraviolet radiation prior to installation is 10 calendar days. 430 Page 300The horizontal and vertical flow of water within the geocomposite sheet drain will interconnect at all times for the full height of the core. The drainage core with the goetextile laminated to one side of the core will provide a minimum flow rate of 5 gallons per minute per foot of width when tested in accordance with ASTM D4716 under the following test conditions: 1.12 inch long specimen 2.Applied load of 10 psi 3.Gradient of 1.0 4.100 hour seating period 5.Closed-cell foam rubber between platens and geocomposites If the core construction separates the flow channel into two or more sections, only the flow rate on the in-flow face is considered in determining the cores acceptability. The geotextile will be firmly attached to the core so folding, wrinkling, or other movement cannot occur either during handling or after placement. Attachment will be through the use of a non-water- soluble adhesive, heat sealing, or other method recommended by the manufacturer. Adhesive will not be used on areas of the geotextile fabric where flow is intended to occur. Heat sealing will not weaken the geotextile below the required strength values.
430.3CONSTRUCTION REQUIREMENTS
A.Underdrain Adjacent to Abutment Backwall: The underdrain system adjacent to the abutment backwall, if specified, will be installed in accordance with the following: 1.Prior to placement of the bridge end embankment and the granular bridge end backfill, polyethylene sheeting will be placed to the specified limits and attached to the abutment backwall with a construction adhesive. The polyethylene sheeting will be placed on impervious soil that has been graded to drain away transversely from the roadway at a rate of 1/8 inch per foot. Lapped joints in the polyethylene sheeting will be placed transverse to the direction of flow with a 1 foot minimum overlap in the direction of flow. Vehicles and equipment will not be operated directly on the polyethylene sheeting. 2.Prior to placement of the bridge end embankment and granular bridge end backfill, the vertical composite drain will be rigidly attached to the abutment backwall such that it will remain in place during backfilling. The method of attachment will be in accordance with the manufacturer’s recommendations. Overlap of the vertical composite drain at splices will be a minimum of 3 inches or as recommended by the manufacturer. Horizontal splices will be such that the top section of the vertical composite drain is over the top of the lower section. 3.Place 2 to 4 inches of porous backfill material on top of the polyethylene sheeting to the limits specified. Care will be taken such that no damage occurs to the polyethylene sheeting during placement of the porous backfill. The porous backfill material will be shaped to receive the 4 inch diameter perforated drainage tubing such that the drainage tubing will be immediately adjacent to the vertical composite drain and will drain transversely away from the roadway at a rate of 1/8 inch per foot. The perforated drainage tubing will then be backfilled with porous backfill to the specified limits. A galvanized wire mesh rodent screen will be installed to the outlet end of the black steel pipe. Drainage 430 Page 301fabric will be placed on top of the porous backfill to the specified limits and attached to the vertical drain composite with a construction adhesive. B.Bridge End Embankment and Granular Bridge End Backfill: 1.The granular bridge end backfill will be placed to the specified limits in accordance with the following and the bridge end embankment will be placed to the specified limits in accordance with Section 120, except as modified by the following: a.It may be necessary for material for the bridge end embankment to be stockpiled during the grading operations. It is the responsibility of the Contractor to coordinate his work such that the required embankment material is available when needed. b.Prior to placing the bridge end embankment, the approach berm will be scarified to a minimum depth of 6 inches and recompacted to a minimum of 97% of maximum dry density as determined by SD 104. c.The bridge end embankment will be continuously benched into the existing roadway embankment. d.The bridge end embankment and the granular bridge end backfill will be built simultaneously in horizontal layers. Bridge end embankment will not exceed 8 inch loose lifts. Granular bridge end backfill will not exceed 4 inch loose lifts. Each layer will be compacted before the next layer is placed. e.The bridge end embankment will be compacted to a minimum of 97% of maximum dry density. Soil used to construct the embankment will have an optimum moisture of less than 25%. Maximum dry density and optimum moisture will be determined by SD 104. f.Granular bridge end backfill will be compacted with at least 4 complete passes using a smooth face vibratory roller or vibratory plate compactor. Each layer of granular material will be thoroughly watered prior to and during compaction. g.Additional density tests will be performed by the Department on the bridge end embankment material behind each abutment. The density testing and moisture testing frequency will be in accordance with the Department’s Materials Manual. The density tests will be evenly spaced between 1 foot above the bottom of the abutment backwall and the theoretical subgrade elevation under the approach slab area. 2.For phased construction, the edge of the first phase of bridge end embankment and granular bridge end backfill between phases will be mechanically stabilized in accordance with the plans details and the following: a.Each layer of granular bridge end backfill, and bridge end embankment will be inspected and approved by the Engineer prior to the placement of the next layer. b.Any equipment used to install the granular bridge end backfill and the bridge end embankment over the geotextile fabric will be operated in such a manner that the geotextile fabric is not damaged. To avoid damage to the geotextile fabric, the 430 Page 302equipment used to place, spread, and compact material over the geotextile will not be operated on less than 6 inches of material. c.The geotextile fabric may be oriented in any direction. To minimize the horizontal deflection of the mechanically stabilized vertical face, it is extremely important to make sure that the geotextile fabric is taut and free of wrinkles during placement of the bridge end embankment and granular bridge end backfill material. d.Any geotextile fabric that is torn or punctured will be repaired or replaced by the Contractor at no additional cost to the Department. The repair will consist of a patch of the same type of geotextile fabric being placed over the ruptured area such that it overlaps the damaged area a minimum of 3 feet measured from any damaged edge. A sewn patch meeting the same requirements for seam strength as that of the fabric being repaired is allowed. e.Seams that are perpendicular to the face of the mechanically stabilized backfill may be constructed by overlapping the fabric a minimum of 2 feet. All other seams, as well as those in which the 2 foot minimum overlap cannot be accomplished, will be sewn. All seams will be inspected by the Engineer and any deficient seams repaired by the Contractor prior to placement of the next layer of embankment or backfill material. Geotextile fabric that is joined by sewn seams will have strength properties at the seam equal to the specified strength requirements of the geotextile fabric. High strength polyester, polypropylene, or Kevlar thread will be used for sewn seams. Nylon threads will not be used. The edges of the fabric will be even and will be completely penetrated by the stitch. f.During periods of shipment and storage, the geotextile fabric will be enclosed in a heavy duty opaque wrapping such that the fabric is protected from direct sunlight, ultraviolet rays, dirt, and debris. The geotextile fabric will not be subjected to temperatures greater than 140°F. C.Approach Slab Underdrain: The bridge end embankment will be placed to the specified limits prior to excavation for the approach slab underdrain. The excavation for the approach slab underdrain will be to limits specified and will be done with minimal disturbance to the underlying material. Excavation for the 8 to 12 inch wide trench will be by a method that will provide a nearly vertical sided trench with the least amount of disturbance to the underlying soil. The bottom of the trench will be graded to drain away transversely from the roadway at a rate of 1/8 inch per foot. The 4 inch diameter perforated drainage tubing will be placed in the bottom of the trench. Porous backfill material will then be placed in the trench and compacted to the satisfaction of the Engineer.
430.4METHOD OF MEASUREMENT
A.Granular Bridge End Backfill: The quantity specified on the plans is the theoretical quantity based on plans dimensions. The plan quantity will be the quantity accepted for payment. Field measurement for granular bridge end backfill will not be made. 430 Page 303B.Bridge End Embankment: The quantity specified on the plans is the theoretical quantity based on plans dimensions. The plan quantity will be the quantity accepted for payment. Field measurement for bridge end embankment will not be made. C.Porous Backfill: The quantity specified on the plans is the theoretical quantity based on plans dimensions. The plan quantity will be the quantity accepted for payment. Field measurement for porous backfill will not be made. D.Approach Slab Underdrain Excavation: The quantity specified on the plans is the theoretical quantity based on plans dimensions. The plan quantity will be the quantity accepted for payment. Field measurement for approach slab underdrain excavation will not be made. E.Underdrain Pipe: The quantity specified on the plans is the theoretical quantity based on plans dimensions. The plan quantity will be the quantity accepted for payment. Field measurement for underdrain pipe will not be made. F.Precast Concrete Headwall for Drain: The precast concrete headwalls for drain will be measured by the number of complete precast concrete headwalls furnished and installed.
430.5BASIS OF PAYMENT
A.Granular Bridge End Backfill: The accepted quantity will be paid for at the contract unit price per cubic yard. Payment will be full compensation for all labor, equipment, materials, water, and all other items incidental to furnishing and installing the polyethylene sheeting, vertical drain composite, drainage fabric, geotextile fabric, and granular bridge end backfill material. B.Bridge End Embankment: The accepted quantity will be paid for at the contract unit price per cubic yard. Payment will be full compensation for all labor, equipment, materials, water, and all other items incidental to furnishing and installing the geotextile fabric and for furnishing and installing the embankment material, including any hauling or stockpiling required. C.Porous Backfill: The accepted quantity will be paid for in accordance with Section 680.5 . D.Approach Slab Underdrain Excavation: The accepted quantity will be paid for at the contract unit price per cubic yard. Payment will be full compensation for all labor, equipment, materials, and all other items incidental to excavating the material to the specified limits, including disposal of the excavated material. E.Underdrain Pipe: The accepted quantity will be paid for in accordance with Section 680 except payment will be full compensation for all labor, equipment, materials, and all other items incidental to furnishing and installing the drainage tubing, black steel pipe, fittings, rodent screens, and vertical drain composite. F.Precast Concrete Headwall for Drain: The accepted quantity will be paid for at the contract unit price per each. Payment will be full compensation for all labor, equipment, materials, and all other items incidental to furnish and installing the precast concrete headwalls. 435 Page 304435 APPROACH SLAB UNDERDRAIN SYSTEM
435.1DESCRIPTION
This work consists of excavating in place materials under the limits of a new approach and sleeper slab and installing a drainage system under the sleeper slab when no other bridge end backfill work is specified. Approach slab underdrain systems installed in conjunction with bridge end backfill work will be completed in accordance with Section 430.
435.2MATERIALS
A.Porous Backfill: The porous backfill material will conform to the requirements of Section 800 with the following modifications: The material will consist of natural sand. Crushed material is not acceptable. The percentage of material passing a #200 sieve will not exceed 2.0%. B.Granular Bridge End Backfill: The granular bridge end backfill material will conform to Section 882. C.Drainage Fabric: The drainage fabric will conform to Section 831 (Drainage Fabric-Type B). D.Polyethylene Sheeting: The polyethylene sheeting will be a minimum thickness of 6 mils and will be sufficiently durable so the polyethylene sheeting will not puncture or tear when installed as intended. E.Drainage Tubing: The drainage tubing will be corrugated polyethylene drainage tubing conforming to Section 990. F.Black Steel Pipe: The black steel pipe will conform to ASTM A53.
435.3CONSTRUCTION REQUIREMENTS
A.Excavation Requirements: Excavation for placement of the new approach slab underdrain system will be done with minimal disturbance to the underlying material. Excavation for the 8 to 12 inch wide trench will be by a method that will provide a nearly vertical sided trench with the least amount of disturbance to the underlying soil. The bottom of the trench will be graded to drain away transversely from the roadway at a rate of 1/8 inch per foot. B.Installation Requirements: After the existing approach pavement has been removed and the ground surface has been shaped for placement of the granular bridge end backfill material, the Engineer will inspect the area. Those areas with predominately 3/8 inch diameter or larger in place aggregate will be covered with Type B drainage fabric prior to placement of the granular bridge end backfill material. The surfaces on which the drainage fabric is to be placed will be smooth and free of obstructions. Lapped joints in the drainage fabric will be placed transverse to the direction of