Excavation and backfilling specifications, 10th Ave Tunnel

NYC 9/11 Public Portal Document

drilled holes shall be cut to achieve a complete separation of the rock formation along the broached line. J. In areas i4iere footings and foundation walls are to be constructed, excavate to the grades indicated on the Drawings, and to rock which meets the New York City Building Code requirements for a bearing value of 40 tons per square foot. Rock underpinning for the existing West Yard building, under caissons for the 10th and 11th Avenue bridges, and under jacking apparatus for the north access tunnel, shall meet the New York City Building Code requirements for a bearing value of 60 tons per square foot. 1. Immediately after approver of the bearing capacity of’the footing by the Engineer, all seams and fissures in the rockat bottoms of footings , shall be grouted. Top of the sealed surface shall be at the design elevation of the bottom of the footing. 3.03 EXPLOSIVES AND BLASTING A. The Contractor shall make himself fully aware of the character, use, and occupancy of adjoining buildings prior to start of blasting operations and shall regulate his work accordingly. - B. Where blasting is required, use only persons skilled and experienced in such work. Handle and store detonators and explosives, and conduct blasting operations in strict conformance with the regulations and ordinances of the authorities having jurisdiction, and as required to avoid damage to property and injury to persons. All blasting shall be done by a licensed blaster. C. Charges shall be of such power and so placed that the blasts will not make the excavations unduly large, will not shatter ealjoining rock, and will; not cause movanent or damage to.utilities, structures.or other; work in the vicinity. Properly cover each blast with steelmats. Blastingcaps shall be of a type that wiIT not be affected by the presence of live contact rail, signal and electrical equipment, radio transmissions or.railroad operations in the existing railroad tunnel. Detonating devices shall conform to local codes and to Amtrak requirements. The Contractor shallsubmit his proposed procedures and materials for blasting to the Engineer for approval^ 0. Comply with applicable paragraphs of the "Manual of Accident Prevention in Construction of A6CA Inc.", which shall form a part of these Specifications. • Comply with applicable requirements of OSHA. „ . E. Conduct pre-blasting surveys and keep accurate logs of each detonation. Make logs available to the Engineeer.. F. Design the blasting procedure including delays so that vibrating velocities measured along the property line do not exceed 1.0 inch per second except along the east^ side of the Site (West Yard Building) where the vibration velocities are limited to 0.5 inch per second. In no Case Shall the peak particle velocity exceed 2.0 inches per second at the pipe or structure nearest to the blast site. The design of the blasting procedure shall be based upon trial detonations made in areas designated by the Engineer. The results of these detonations shall be monitored by a seismologist engaged by the Authority. Vibration velocities in the existing Amtrak North River Tunnels shall, not exceed the ambient levels caused by the simultaneous passage of a train in each tunnel, and in no case shall peak particle velocity exceed 1 inch per second. Contract 02220-8 Excavation and 1-02-21064-0-0 Backfill

NYC-WTC_000165815