are the responsibility of the contractor and the bridge/culvert supplier.
620.6 -CONSTRUCTION METHODS : 620.6.1 -Precast Three -Sided Br idge/Culvert: 620.6.1.1 -Footings: The bridge/culvert units shall be installed on cast -in-place concrete footings. The elevation of the bottom of the footing shall be equal to or lower than the elevation as shown on the plans. A keyway for grouting with a minimum depth of three ( 3) inches shall be formed in the top surface of the footing and the keyway shall extend to where three ( 3) inches clear of the inside and outside faces of the bridge/culvert unit, unless specified otherwise on the plans or by the bridge/culvert system supplier. The footings shall be given a rough float finish and shall reach a compressive strength of 2,000 psi before placement of the bridge/culvert units. The completed footing surface shall be constructed in accordance with grades shown on the plans. When tested with a 10 foot straight edge, the top surface of the footings shall not vary more than ¼ inch in ten (10) feet. The foundation is to be constructed in accordance with the approved shop drawings.
620.6.1.2 -Placement of the Bridge/Culvert Units: A representative of the manufacturer shall be present during the first three days the structure is being placed. The units shall be placed as shown on the Engineer’s plan drawings. Special care shall be ta ken in setting the units to the true line and grade. The units shall be set on masonite or steel shims at least five ( 5) inches square, or on a concrete leveling pad cast inside the keyway. When set on shims a minimum of a ½ inch gap shall be provided bet ween the footing and the base of the unit leg. Prior to grouting three sided structures with legs that have a curved exterior surface, the legs shall be supported horizontally using hardwood wedges driven between the outside of the structure leg and the w all of the keyway. The requirements for the grout will conform to subsection 715.5 and testing of the grout shall be performed by the Contractor in accordance with ASTM C109, as modified by ASTM C1107. Compressive strength of the grout shall be at least XXXX psi at X days as determined by the average result of three test specimens. Wedges shall be spaced no more than two (2) feet apart along both sides of the structure.
620.6.1.3 -External Waterproofing: When specified on the plans and the limits of application are shown, a waterproofing membrane as described below shall be applied to the top and the sides of the structure unless the top of the structure is to be the driving surface. The material should be installed per the waterproofer manufacturer’s instructions.
Property Value 1 Test Method Strip Tensile 50 lbs./in. ASTM D8822 Puncture Resistance 200 lbs. ASTM E154 Permeance 0.10 perms (max.) ASTM E96, Method B Pliability No cracks in fabric or rubberized asphalt ASTM D1463 1 Minimum average roll values unless otherwise noted 2 Using 12 in/min test speed and 1” initial distance between grips. 3 Using 180 ° bend on ¼ inch mandrel at -25°F
476 The surface shall be free of dirt before applying the waterproofing material. A primer compatible with the waterproofing membrane to be used shall be applied before the membrane is installed. The structure should be covered continuously from the bottom of one bridge/culvert unit leg, across the top of the structure and to the bottom of the opposite bridge/culvert unit leg. The joint between the end unit and the headwall shall also be sealed by carrying the membrane up the headwall at least four ( 4) inches. If precast wingwalls are used, the joint between the wingwall and the end units should be covered in a similar fashion, or, at the discretion of the engineer, filter fabric can be substituted.
620.6.1.4 -Backfill Placement: Backfill shall be considered as all replaced excavation and new embankment adjacent to the precast bridge/culvert units and wingwalls. The project construction and material specifications, which include the specifications for excavation for structures and roadway excavation and emban kment construction, shall apply except as modified in this section. No backfill shall be placed against any structural elements until they have been approved by the Engineer. No backfill shall be placed against the structure until the grout has cured for a minimum of 12 hours. On three sided structures with legs that have a curved exterior surface the grout shall be cured for a minimum of 72 hours before placing backfill against the structure. Backfill against the waterproofing membrane when specified on the plans shall be placed carefully to avoid damage to the waterproofing material. Mechanical tampers or approved compacting equipment shall be used to compact all backfill and embankment immediately adjacent to each side of the bridge/culver t and over the top of the bridge/culvert until it is covered to a minimum depth of one (1) foot. The backfill within four ( 4) feet of each side of the bridge/culvert shall be placed in lifts of eight (8) inches or less (loose depth). Heavy compaction equi pment shall not be operated in this area or over the bridge/culvert until it is covered to a depth of 1 foot. Lightweight dozers and graders may be operated over culverts having one ( 1) foot of compacted cover, but heavy earth moving equipment (larger tha n a D -4 Dozer weighing in excess of twelve ( 12) tons and having track pressures of eight (8) psi or greater) shall require two (2) feet of cover unless the design cover is less than two (2) feet. In no case shall equipment operating in excess of the desig n load be permitted over the bridge/ culvert unless approved by the E ngineer. Any additional fill and subsequent excavation required to provide this minimum cover shall be made at no additional cost to the project. When placing backfill at no time shall the difference between the heights of fill on opposite sides of the bridge/culvert exceed 18”. Backfill in front of wingwalls shall be carried to ground lines shown in the plans.
620.6.2 -Cast -in-Place Reinforced Concrete: Except as otherwise shown in the plans or herein, construction methods for cast -in-place three -sided structures shall comply with the Specifications. When specified on the plans, a waterproofing membrane per section 620.6.1.3 shall be applied to the exterior top and the sides of the structure. Construction methods for the following shall be per the indicated section of the Specifications:
477 ITEM SECTION Unclassified Borrow Excavation 211 Structure Excavation 212 Rock Excavation 212 Wet Excavation 212 Select Material for Backfilling 613.5.11 Concrete 601 Reinforcing Steel 602
620.7 -METHOD OF MEASUREMENT : Excluding headwalls and wingwalls, three -sided bridge/culverts shall be measured by the linear foot, the measurement being along the centerline of the bridge/culvert and extending from the exposed face to exposed face of the headwalls. Wingwalls shall be measured by the unit. A wingwall is the entire end section for the three - sided structure including but not limited to headwalls, aprons, foundations for the wingwall, cut - off walls and appurtenances. There shall be no measurement and payment for headwalls. Headwalls shall be incidental to and include d in the unit bid price of the wingwalls. There shall be no separate measurement and payment for the excavation required for installing the bridge/culvert, including any undercut to establish an adequate foundation. Excavation, whether unclassified, stru cture, rock or wet excavation shall be incidental to and included in the unit bid price for the bridge/culvert and wingwalls. There shall be no separate measurement and payment for backfill below an elevation two feet above the top or crown of the outside of the bridge/culvert whether such backfill is unclassified borrow, select rock fill, select backfill or salvaged existing streambed material. All such backfill shall be incidental to and included in the unit bid price for the bridge/culvert and wingwalls. There shall be no separate measurement and payment for waterproofing membrane if the waterproofing membrane is specified on the plans and the limits of application are shown. Concrete and backfill shall be placed under dry conditions. Should cofferd ams, pumping or other methods be necessary to maintain dry conditions, the cost of these methods shall be incidental to and included in the unit bid price for the bridge/culvert and wingwalls. If the maintenance of traffic scheme necessitates the use of s heet piling or bulkheads during the installation of the bridge/culvert, the cost of piling and bulkheads shall be incidental to and included in the unit bid price for the bridge/culvert and wingwalls. If the design necessitates undercutting the foundation and backfilling to the footing elevation with select rock fill, the select rock fill shall be separated from soils with fabric for separation per subsection 715.11.8. The cost of the fabric shall be incidental to the unit bid price for the bridge/culvert and wingwalls. The cost of the construction layout work shall be incidental to and included in the unit bid price for the bridge/culvert and wingwalls. Additional work arising from changed conditions found during the construction from those shown on th e approved drawings shall be paid in accordance with subsection 109.4.
620.8 -BASIS OF PAYMENT : The quantities, determined as provided above, will be paid for at the contract price per unit of measurement, respectively, for each pay item listed below and shown in the bid schedule, which prices and payment will be full compensation for the work prescribed in this section.