Excavation and backfilling specifications, 10th Ave Tunnel

NYC 9/11 Public Portal Document

J. The existing Amtrak tunnels shall be continuously inspected by the Contractor from the inside. Any damage such as cracks, falling bricks or loosening of bricks or mortar shall be immediately reported to the Engineer. The Contractor shall modify his excavation procedure to prevent further damage. All damage to the tunnels caused by the Contractor's operations shall be repaired to the satisfaction of Amtrak and the Engineer at no cost to the Authority. K. where there is less than four feet of cover above the section line of the Amtrak tunnels, construction equipment weighing more than 1,000 lbs. gross weight shall not be used in the backfilling and compaction work. Where more than four feet of cover exists over the section line, equipment having a gross weight of up to 10 tons may be utilized. 3.12 EXCAVATION PROCEDURES - TENTH AVENUE BRIDGE AREA A. Excavation of rock within 50 feet of the Tenth Avenue Bridge may not begin until broaching in the area of the bridge has been completed to subgrade elevation. Line drilling in the area may be done in two equal vertical lifts provided line drilling for each lift is done prior to the start of production blasting for that lift; B. The excavation shall proceed in a west to east directiion. Blasting and excavation of rock east of the centerline of Tenth Avenue may not proceed until the underpinning of the West Yard Building has been completed. C. Rock east of the broach line, lying on the easterly property line of Tenth Avenue, may not be removed prior to excavation of all rock to the west of this line. Blasting in this area will not be permitted. D. Removal of rock for a 15 foot width, as measured at right angles to the broach line at the south abutment, shall be made in sections coinciding with each section of the abutment stem. A section is defined as that portion between construction joints. Removal of rock may be made on alternate sections simultaneously. Sections of rock remaining may not be removed until adjacent abutment sections have been placed and concrete has achieved 28 day strength. The length of sections as defined above will be increased, as approved by the Engineer, to allow room for reinforcing bar splices.

3.13’ BACKFILLING A. General: Backfill with approved backfill material. Place backfill as promptly as work permits but not until completion of the following: 1. Acceptance by the Engineer of the construction below finish grade including waterproofing where applicable. 2. Recording of final location and limits of the structure, and of any utilities or other underground features that will be covered by backfill. 3. Removal of concrete formwork, trash and debris.

Contract 02220-12 Excavation and 1-02-21064-0-0 Backfilling

NYC-WTC_000165819