11831 AIRPORT RD WHOLE SITE FILE 2020-01-21

2. Final shaft depths shall be measured with a suitable weighted tape or other approved methods after final clean-out. 3. Shaft cleanliness will be determined by the Engineer,by visual inspection. 4. The excavated shaft shall be approved by the Engineer prior to placing any steel or concrete into the shaft. Reinforcing Steel Cage Construction and Placement 1. The reinforcing steel cage consisting of longitudinal bars, ties, cage stiffener bars, spacers, centralizers, and other necessary appurtenance shall be completely assembled and placed as a unit immediately after the shaft excavation is inspected and accepted prior to concrete placement. The reinforcing cage shall be rigidly braced to retain its configuration during handling and when lowered into the shaft, during placement of concrete and extraction of the casing from the shaft. No loose bars will be permitted. The reinforcing steel fabricator shall include bracing and any extra reinforcing steel required to fabricate the cage in the shop drawings. 2. If the bottom of the constructed shaft elevation is lower than the bottom of the shaft elevation in the Plans, a minimum of 1/2 of the longitudinal bars required in the upper portion of the shaft shall be extended the additional length. Tie bars shall be continued for the extra depth, spaced on 2 feet centers, and the stiffener bars shall be extended to the final depth. These bars may be lap spliced, or unspliced bars of the proper length may be used. Welding to the planned reinforcing steel will not be permitted unless specifically shown in either the Plans or Special Provisions. 3. The reinforcing steel in the shaft shall be tied and supported so that the reinforcing steel will remain within allowable tolerances given in this Specification. Concrete spacers or other approved noncorrosive spacing devices shall be used at sufficient intervals (near the bottom and at intervals not exceeding 5 feet up the shaft) to insure concentric spacing for the entire cage length. Spacers shall be constructed of approved material equal in quality and durability to the concrete specified for the shaft. 4. The elevation of the top of the steel cage shall be checked before and after the concrete is placed. If the rebar cage is not maintained within the specified tolerances, corrections shall be made by the Contractor as directed by the Engineer. No additional shafts shall be constructed until the Contractor has modified his rebar cage support in a manner satisfactory to the Engineer. Concrete Placement Concrete placement shall commence within 2 hours after completion of the excavation and shall be placed in one continuous operation to the top of the shaft. Concrete shall be placed through a tremie. The tremie used shall consist of a tube of one-piece construction. Concrete shall be placed through a hopper at the top of the tube so that the concrete is deposited through the center of the reinforcing steel to prevent segregation of the aggregates and splashing of concrete on the reinforcement cage. The Contractor's 11 Swift II BRT Boeing to Canyon Park Station—Traffic Signal 90%Special Provisions—12/1/2016