Excavation and backfilling specifications, 10th Ave Tunnel

NYC 9/11 Public Portal Document

2. Provide sheeting and bracing at excavations where required by the Drawings, or where sloping is not possible due to space restrictions or the nature of the material excavated. 3. Maintain sides and slopes of excavations in safe condition until backfilling is completed. 4. Where the Contractor elects to slope the sides of excavations, backfill of the over-excavated areas shall be made in the same manner specified for the adjacent excavated area. All additional backfill required shall be at no additional cost to the Authority. 5. Where indicated on the Drawings, excavations in rock shall be made by vertical line drilling in a manner that will provide a safe, secure vertical cut as approved by the Engineer. 6. Where vertically line-drilled rock is to be used as a back form for the walls of the concrete structures, provide for a continuous approved type separating form liner between the concrete and,rock where required by the Drawings. In such Instances, the line of the rock cut shall provide for the placing of the liner and the full dimension’of the concrete shown on the Drawings. <7. D. Filling of Voids: 1. Where vertical structural components are to be placed against an excavated face, or against a bond breaking form liner placed on the excavated face, no voids shall be left between the back of; the vertical structural element and the excavated face or the liner. In each instance, the structural concrete of the vertical element shall be extended to the actual excavated face or to the bond breaking’liner placed against the excavated face. , .... I'e -. .n , 2. Voids that occur between the form liner and the excavated face shall be filled with 3000 psi concrete where the voids are 3 Inches or greater, and with Portland cement grout where the voids are less than 3 inches. The Contractor shall obtain the written approval of the Engineer for the methods of placing such concrete or grout. . 3. Any additional concrete provided for the elimination of voids behind vertical structural elements, and any concrete or grout used to fill voids behind form liner, shall be provided at no additional cost to the Authority. E. Excavation for Structures; 1. Excavate to required lines and grades. 2. In rock areas excavate so that concrete for foundations or mud slabs bears on solid, firm bedrock. Remove all loose materials clean out fissures. Where required, pressure grout cavities and fractures as approved.

Contract 02220-6 Excavation and 1-02-21064-0-0 Backfilling

L NYC-WTC_000165813