716TRENCHLESS PIPE INSTALLATION

716.01Description

This work shall consist of installing pipes underground using construction techniques that eliminate open cutting of the pavement or of the ground in accordance with 105.03. This specification addresses auger boring, guided boring, horizontal directional drilling using a reamer diameter up to and including 24 in., pipe jacking, and pipe ramming, as defined below.

Installations by means of directional drilling which require a reamer larger than 10 24 in., microtunneling, or other tunneling methods, may be utilized if approved by the Engineer. The Contractor shall submit a detailed proposal prepared by a professional engineer for installations other than auger boring, guided boring, horizontal directional drilling using a reamer diameter less than 24 in., pipe jacking, and pipe ramming.

The following definitions apply to trenchless pipe installation.

Technique for forming a bore from a drive shaft to a reception shaft, by means of a rotating cutting head. Spoil is removed back to the drive shaft by helically wound 20 auger flights rotating in a steel casing.

The tube which carries the product being transported and which may pass through casings at highway or railroad crossings. It may be made of steel, concrete, clay, thermoplastic, ductile iron, or other materials.

A pipe installed as external protection to a carrier pipe.

Excavation from which trenchless technology equipment is launched. It may incorporate a thrust wall to spread reaction loads to the soil.

A trenchless tunneling method that utilizes small diameter pilot tubes that are installed and steered through the ground utilizing a slanted face at the cutting head containing a target with light emitting diodes, LEDs, and a camera mounted theodolite located in the shaft to achieve high accuracy in line and grade. The hole is enlarged to the same outside diameter of the final product pipe after the installation of the pilot 40 tubes, which is then jacked into place.

A steerable system for the installation of pipes, conduits, or cables in a shallow arc using a surface launched drilling rig.

716.01

A remote controlled trenchless construction method that simultaneously installs pipes as the soil is excavated. This method provides continuous support of the excavation face with slurry pressure to balance groundwater and earth pressures. 50

A system of directly installing pipes behind a shield machine by means of hydraulic jacking from a drive shaft such that the pipes form a continuous string in the ground.

A non-steerable system of forming a bore by driving an open-ended steel casing using a percussive hammer from a drive shaft. The soil may be removed from the casing by augering, jetting, or compressed air. 60

Excavation into which trenchless technology equipment is driven and recovered following the installation of the pipe.

Pre-established levels of instrument readings of settlement or of other monitored behavior such as lateral movement or vibrations, which trigger the implementation of mitigative measures. Response levels consist of the initial review level, at which mitigative measures must be implemented, and the alert level, at which construction 70 must be halted and actions taken to ensure the alert level will not be exceeded in subsequent construction.

Earth, rock, or other materials displaced by a tunnel or casing, and removed as the tunnel or casing is installed.

MATERIALS

716.02Materials 80

Materials shall be in acco rdance with the following:

Clay Pipe, Extra Strength ............................................ 907.08 PVC Pipe ..................................................................... * Reinforced Concrete Pipe ............................................ 907.02 Smooth Wall Polyethylene Pipe .................................. * Steel Pipe ..................................................................... 908.11 Water ........................................................................... 913.01 * All thermoplastic pipes shall be from the QPL of Thermoplastic Pipe 90 and Liner Pipe Sources in accordance with 907.16.

Concrete pipe shall be from the QPL of Certified Precast Concrete Producers. 716.02

Concrete pipe installed by pipe jacking shall be designed with sufficient concrete strength and steel reinforcement to resist jacking forces and shall have tongue and groove joints. All reinforced concrete pipes shall have steel reinforcement concentric with the pipe wall.

Steel pipe used as a carrier pipe shall have the following minimum wall thickness. 100 Steel pipe used as a casing pipe, but not used as a carrier pipe, shall be selected by the Contractor to have minimum wall thickness sufficient to resist jacking forces. For installations where the casing is not used as a carrier but only as a casing for a carrier pipe, the thickness of the casing shall be determined by the Contractor.

Outside Diameter, in. Wall Thickness, in. 18 or less 1/4 19 – 20 5/16 21 – 26 3/8 27 – 30 1/2 31 – 42 1/2 43 – 48 9/16

CONSTRUCTION REQUIREMENTS

716.03General Requirements

The Contractor shall submit a QCP in accordance with ITM 803. The QCP shall 110 be submitted to the Engineer for review and acceptance, at least 15 days prior to the start of trenchless pipe installation operations.

Where groundwater is known or anticipated, and where the technique selected for trenchless pipe installati on does not provide positives upport at the trenchless excavation face, such as by slurry support in microtunneling, then trenchless pipe installation shall not proceed without dewatering in advance of trenchless pipe installation. A dewatering system of sufficie nt capacity to handle the flow shall be maintained at the site until its operation can be safely halted. The dewatering system shall be equipped with screens or filter media sufficient to prevent the displacement of 120 fines.

Where the use of explosives is necessary for performing the work, their use shall be in accordance with 107.13.

Bentonite or other suitable lubricants may be applied to the outside surface of the pipe to reduce frictional forces.

Joints in steel pipe shall be watertight. Where welded joints are utilized, they shall be welded in accordance with 711.32. Joints in concrete pipe or other jacking pipe 130 materials, including clay pipe, shall be designed to withstand the additional forces that 716.03

are created in the joints during the installation process. The joints in concrete pipe or other pipe jacking materials shall be protected with a resilient material around the circumference of the pipe. Resilient material shall also be used between the pipe and the thrust ring.

Pavement or ground surface heave or settlement resulting in damage to pavement, existing utilities, or structures above the installation will not be allowed. To confirm if heave or settlement is occurring, the Contractor shall undertake surface monitoring.

Installations shall have a bored hole esse ntially the same diameter as the outside of the installed pipe. If voids develop or if the bored diameter is greater than the outside diameter of the pipe by more than 1 in., grouting shall be used to fill such voids.

When the installation is 4 in. or larger and the casing is used as the carrier pipe, a visual or a video inspection shall be performed using a high resolution, high sensitivity color video camera and recording equipment. The pipe shall be cleaned of debris prior to the inspection. Cleaning shall be accomplished by means of water jetting or other approved methods.

The camera and recording equipment shall be specifically designed for continuous viewing and recording of detailed images of the interior wall of pipes and transitions of the specified sizes. The equipment shall include sufficient lighting to view the entire periphery of the pipe. The equipment shall have appropriate attachments to maintain a position in the center of the pipe and an electronic counter to continuously record the location of the equipment in the pipe. A copy of the video inspection shall be submitted to the Engineer.

All sections of pipe found to be damaged or where joint failure is evident shall be repaired or replaced as approved by the Engineer. 160

If an obstruction is encountered during installation which stops the forward progress of the pipe, and it becomes evident that it is impossible to advance the pipe, the Engineer shall be notified. For installations utilizing tunnel shields or tunnel-boring machines or other methods that allow access to the face, the obstruction shall be removed in accordance with the QCP. For in stallations utilizing methods that do not allow access to the face, at th e direction of the Engineer, the pipe shall be abandoned in place and filled with grout or other approved materials.

Where a gravity-flow carrier pipe is pl aced inside a casing pipe, the gravity-flow 170 carrier pipe shall be shimmed to proper line, elevation, and grade and then the void between the two pipes shall be grouted with cellular grout.

Upon completion of the installation of the pipe, all excavated areas not occupied by the pipe shall be backfilled and compacted with suitable material in accordance with 203.

716.03

716.04Method of Measurement

Pipe installed by means of trenchless installation methods will be measured by the linear foot along the center line of the pipe installed. 180

716.05Basis of Payment

Pipe installed by means of trenchless in stallation methods will be paid for by the linear foot for pipe installation, trenchless, of the size specified, complete and in place including all incidentals.

Removal of boulders, concrete, or other obstructions will be paid in accordance with 104.03.

Payment will be made under: 190

Pay Item Pay Unit Symbol

Pipe Installation, Trenchless, _____ .......................................... LFT size

The cost of the QCP, excavating and backfilling of the drive shaft and reception shaft, video inspection, camera and recording equipment, bentonite or other lubricant, grout, and the casing if installed shall be included in the cost of pipe installation, trenchless. 200

If a partial installation has to be aba ndoned in place and filled with grout due to the encountering of an obstruction, the abandoned work will be paid for at 75% of the contract unit price of the pipe installed.

No payment will be made to repair or replace sections of pipe that have been damaged or show evidence of joint failure.