728Jacked or Bored Pipe

728.01 DESCRIPTION. Furnish and install pipe in embankments at the

locations shown on the plans by jacking or boring in accordance with these specifications.

728.02 MATERIALS. Pipe materials shall comply with 701.02 and

1018.03 Pipe joints shall comply with 701.06. Corrugated metal pipe to

be jacked or bored shall have corrugated bands a minimum of 24 inches wide with four lines of approved gasket material. Secure these bands by a minimum of four galvanized steel rods and lugs in accordance with the plans and as directed.

728.03 CONSTRUCTION REQUIREMENTS. In general, jack pipes

30 inches diameter and greater and bore pipes less than 30 inches diameter. Begin the work at the outfall end of pipe when possible. When the grade at the jacking or boring end is below ground surface, excavate suitable pits or trenches for conducting operations and placing joints of pipe. Provide adequate sheeting and bracing to prevent earth caving. For pipe with bell joints, if the outside diameter of the pipe bell exceeds the outside diameter of the pipe barrel by more than 1 inch , either case the pipe or pressure grout its full length. Furnish and install an approved type and size casing, in accordance with these specifications. Pressure grout with approved materials placed by approved methods. The method used shall not weaken or damage the embankment. Provide for approval a plan showing the proposed procedure, including backstop or jacking frame arrangement, pipe guides, position of jacks, and jacking head. Approval of this plan shall not relieve the contractor from responsibility for obtaining the desired result.

728.03.1 Jacking: Provide heavy duty jacks suitable for forcing pipe

through the embankment. Apply equal pressure to all jacks and transmit the pressure to the pipe end through a jacking head. Design the jacking head so that pressure is uniformly applied around the ring of the pipe. Provide a backstop or jacking frame to adequately resist pressure of the jacks under load. Set pipe on guides properly fastened together to support the pipe in the proper direction at correct grade. Provide suitable cushioning material, such as plywood, between sections of concrete pipe. Excavate material ahead of the pipe and remove through the pipe. Do not extend excavation more than 24 inches beyond the forward end of pipe. When the character of embankment material dictates, reduce the excavation distance to prevent the embankment from being damaged. Dispose of excavated material in accordance with 202.02. When excavating on the underside of pipe, conform to the contour and grade of the pipe for at least one-third the circumference of pipe. Provide a clearance of not more than 2 inches for the upper half of pipe, tapered to zero at the point where excavation conforms to the contour of pipe. Construct a steel cutting edge around the forward end of pipe that will transmit pressures uniformly around the ring of the pipe. Continue jacking without interruption to prevent pipe from becoming firmly set in the embankment. Do not allow pipe to vary horizontally or vertically by more than 1/4 inch per 10 feet from established line and grade. Any variation shall be regular; no abrupt changes in direction will be permitted. Remove and replace any pipe damaged or misaligned in jacking operations at no direct pay.

728.03.2 Boring: Bore mechanically, using a pilot hole

approximately 2 inches in diameter. Extend the pilot hole through the embankment and check for line and grade before boring begins. Maintain the same line and grade variations as specified for jacking. Use the pilot hole as the centerline of the larger diameter hole to be bored. Use water and other fluids with boring operations only to lubricate cuttings. Jetting will not be permitted. In unconsolidated soil formations, a gel-forming colloidal drilling fluid consisting of at least 10 percent high-grade bentonite may be used to consolidate cuttings of the bit, seal walls, and provide support of the hole, and furnish lubrication for subsequent removal of cuttings and installation of pipe. Remedy overcutting in excess of 1 inch by pressure grouting the entire length of the installation. Join pipe in accordance with Section 701.

728.04 MEASUREMENT. Quantities of jacked or bored pipe for

payment will be the design lengths in linear feet as shown on the plans. Design quantities will be adjusted if the engineer makes changes to adjust to field conditions, if plan errors are proven, or if design changes are made. Required excavation, sheeting, bracing, falsework, casing, joint materials, and grouting will not be measured for payment.

728.05 PAYMENT. Payment for jacked or bored pipe will be made at

the contract unit price per linear foot, which includes all labor, materials, equipment, tools, and incidentals necessary to complete the work. Payment will be made under: Item No. Pay Item Pay Unit 728-01 Jacked or Bored Pipe Linear Foot