1. Scope

1.1 This specification covers the basic requirements and installation of segmented polyethylene "Buttress-Loc" pipe for the renewal of sanitary and storm sewers by insertion through existing pipe and along the previously existing line and grade. Refer to ASTM F585 installation guidelines.

1.2 Insertion renewal methods outlined herein are designed to result in minimal surface damage, and little-or-no interruption of customer facilities.

1.3 This specification does not cover all design aspects of environmental conditions such as high water tables, extreme depth, quicksand and earth loading. As with all engineered structures, the consequence of failure under unusual conditions must be assessed.

Suggested supplier: ISCO Industries, LLC; Louisville, KY (800) 345-4726 ext. 232

2. Material Requirements: Pipe liner shall:

2.1 Be manufactured of high-density polyethylene resin in accordance with ASTM D3350-99 with a cell classification of 345464C.

2.2 Have a material designation of PE 3408 by the Plastic Pipe Institute.

2.3 Meet stiffness range as shown in ASTM F714, Appendix X1, Table X1.1

2.4 Have physical properties in accordance with polyethylene material standard ASTM D3350-99 with cell classification 345464C as follows:

2.4.1 Density: 0.955 gms/cubic centimeters per ASTM D1505.

2.4.2 Flexural Modulus: Minimum 135,000 psi per ASTM D790.

2.4.3 Tensile Strength: Minimum 3,200 psi per ASTM D638.

2.4.4 PENT > 100 hours at 80 degrees C, 2.4 Mpa per ASTM F1473.

2.4.5 HDB@ 23 degrees C: 1,600 psi per ASTM D2837.

2.4.6 UV Stabilizer: Minimum 2% carbon black per ASTM D 1603.

2.5 Pipe Selection

2.5.1 Liners are usually 10% smaller OD than the ID of the existing pipe.

2.5.2 "Buttress-Loc" with a DR of 32.5 is used for pipe sizes 24" ID and larger when the hydrostatic pressure around the liner is less than 3.2 feet.

2.5.3 "Buttress-Loc" with a DR of 17 is used for liner sizes of 20" OD and smaller. This DR will handle hydrostatic pressures of 24 feet and less.

2.6 Pipe Joining System: Joining system shall be watertight using threads and screw together.

2.6.1 Threads shall be of buttress design

2.6.2 Joints shall be self-sealing when tightened.

2.6.3 Completed connection will exhibit very high pull out strength without changing the O. D. or the I. D. of the liner pipe.

2.7 Flow Capacity

2.7.1 The liner shall be smooth and non-porous.

2.7.2 The Manning frictional coefficient, "N" value shall be 0.009.

2.7.3 When used in pressure piping systems, the Hazen-Williams Formula frictional coefficient, "C" factor shall be 150.

3.0 Special Equipment

3.1 Video Inspection Equipment: Closed-circuit video recording and videotape equipment is necessary for insertion renewal. It is a very valuable tool during construction when locating laterals.

3.2 Winches-Power & Mechanical: Winches of sufficient capacity are required for cleaning sewers. Power winches for pulling liner should be rated in the 10 to 15 ton range and have ¾" cable with a length of 600 to 1,000 feet. Hydraulic operation is preferable.

3.3 Jacking - Hydraulic & Mechanical: Jacks of sufficient capacity can be used for pushing the liner through the sewer. A special ring is put over the end of the pipe prior to using the jacks to protect the "Buttress-Loc" joint from damage.

3.4 Cleaning Devices for Removing Debris: A cleaning pig is a mechanical device designed for efficiently removing loose debris in sewer lines. Pigs are pulled through sewers between manholes by winches. Water jetting equipment is used to remove loosened debris in structurally sound pipe.

4.0 Installation Procedure

4.1 Pre-Video Inspection: A videotaped inspection is mandatory to accurately locate and assess existing conditions prior to rehabilitation.

4.2 Removing Debris and Obstructions: High Pressure water jetting is normally used for cleaning and removing debris. Obstructions, protruding laterals and heavy root intrusions require mechanical devices to cut and remove them. Partial collapses or extensive sags may require excavation in advance of rehabilitation. A contingency pay item for additional pits is included.

4.3 Sewer Customer Notification: The owner shall notify all customers by letter explaining the nature of work, time of completion and possible use stoppages prior to the start of the project.

4.4 Pipe Joining Procedure: "Buttress-Loc" pipe has a unique joint, which converts short lengths of plastic pipe into continuous pipelines. The system is easily assembled inside a manhole or small excavation. Each length is screwed together with a chain wrench. The joint, when fully tightened, automatically self seals.

4.5 Access Pits for large diameter "Buttress-Loc" Pipe: The size of the pit can be as small as necessary for man entry to install short lengths of insertion pipe. Shoring and bracing is required to meet applicable safety standards.

4.6 Pipe Insertion: Each piece of "Buttress-Loc" pipe is placed on the invert, locked together and hydraulically pushed or winched into the sewer, on at a time. This procedure is continued until the sewer is completely lined. Sewage flow is normally maintained during installation. Pumping and bypass piping may be required for flows in excess of 30% capacity.

4.7 Grouting, Sealing and Anchoring: Once the pipe is inserted and stabilized, the annular space at the upstream manhole is sealed first. Reconnection of laterals is always started at the upstream end so that water flow from unconnected laterals can escape through the annular space. When using close tolerance liners (about 10% of original), grouting the entire annular space is not mandatory. Proper sealing and anchoring at manholes and at lateral connections is all that is necessary. Follow ASTM F585 for guidelines. To restrict movement, the liner pipe may have to be restrained at manholes using stainless steel anchor bolts. This is usually necessary when there are no anchored laterals between manhole sections. Flowable cement grouts to fill the entire annular space may be used at critical crossings such as highways or railways or where liner pipe is considerably smaller than the existing pipe.

5. Lateral Reconnections

5.1 Lateral - Sliplined & Reconnected: Since laterals are also a source of root and water infiltration, it is recommended that they are sliplined and it is recommended that they be sliplined and properly reconnected to the main liner. A small excavation is required at the property line to expose the existing lateral. A window is cut out to allow for rehabilitation using inserted "Buttress-Loc" liner pipe.

5.2 Procedure: Insert and connect short lengths of pipe into the existing lateral until they reach the main sewer liner. An inflatable grout seal unit is fed through the lateral liner and inflated at the main. Expandable grout is then injected against the main liner pipe to make a leak tight seal. A flexible core drilled to reactivate the lateral liner to the main liner follows this. An eccentric reducer is normally installed to make the transition from the new lateral to the existing lateral at the property line. Robotic reconnection and sealing without lateral lining can be provided if acceptable to the owner.

6.0 Finishing Operations

6.1 Benching: Manhole inverts are benched to suit the contour of the new liner.

6.2 Post Video: A post videotaped inspection follows to verify the integrity of the new sewer. A detailed report with photographs and videotape is submitted to the owner for approval.

6.3 Manhole Repairs: Repair of manholes as needed or specified.

Note: For additional installation guidelines refer to ASTM F585 Standard Practice for HDPE. Manufacturer’s literature provides data on pipe stiffness, pressure rating, hydraulic loads, axial bending and radial deflection.