Pipe Bursting Private Side Sewers and Storm Drain Pipes
Supplemental Conditions - Revised December 6, 2018
Unless otherwise specified below, side sewers and storm drain pipes installed by the trenchless methods shall conform to the requirements set forth in the Utilities Engineering Standards .
Since the Owner is opting to use trenchless methods to rehabilitate the existing pipe, it is not possible to make significant adjustments in line and grade. Owner accepts the fact the pipe may have less than minimum pipe slope and that there may be swales in the pipe grade. These minor deficiencies may require more frequent pipeline maintenance by the Owner.
Installation Strain and Temperature Effects
Due to pipe bursting strain and/or temperature effects on high density polyethylene (HDPE) pipe during installation, the HDPE pipe will be required to rest for at least 24 hours or as recommended by the manufacturer, whichever is longer, prior to final pipe cutting to allow the HDPE pipe to achieve equilibrium. No pipe connections or anchoring shall be made prior to the expiration of the rest period.
High Density Polyethylene (HDPE) has a high coefficient of thermal expansion. The installation of a HDPE pipe must account for the expansion and contraction of the pipe material so that pipe separation at the couplings does not occur. This shall be accomplished by installing pipe anchors within three feet of the connecting coupling.
Pipes on Private Property
The contractor shall verify the appropriate dimension ratio of the high-density polyethylene (HDPE) pipe to be used with his/her engineer. The minimum dimension ratio shall be 26.
Outside of the right of way or public easement, the minimum pipe size for gravity lines shall be 4-inch diameter. Joint use pipes must be a minimum 6-inch diameter.
The connection between the HDPE side sewer and the house clean-out at the foundation shall be made with a size-on-size mechanical transition coupling, such as a Romac 501-style coupling, Fernco Strongback-style coupling, or a long pattern DI sleeve, in conjunction with an internal stainless steel stiffening sleeve. Flexible rubber couplings (e.g., standard Fernco and Caulder couplings) are not allowed.
For storm drain pipes, the connection between the HDPE pipe and the existing drain pipe shall be made with a size-on-size mechanical transition coupling, such as a Romac 501-style coupling, Fernco Strongback-style coupling, or a long pattern DI sleeve, in conjunction with an internal stainless steel stiffening sleeve. Flexible rubber couplings (e.g., standard Fernco and Caulder couplings) are not allowed.
- The contractor shall request all inspections that apply to work being performed prior to backfilling including but not limited to all pipe anchors, bends, fittings connections and clean outs.
- A CCTV video inspection of the host pipe after cleaning operations shall be made. A copy of the CCTV inspection shall be provided to the inspector on a USB at final inspection.
- The contractor shall request a post-installation inspection (630 – Side Sewer; 635 – Storm Connection). After running water through the rehabilitated pipe, a CCTV inspection of the pipe shall be made with the inspector present and a copy of the video inspection on a DVD shall be furnished to the inspector. The video shall meet acceptable standards and provide proper speed of the camera and sufficient lighting to enable a thorough visual inspection of the entire rehabilitated pipe including all connection points.
- If the pipe appears to be out of round, the inspector may require the standard mandrill to be pulled through the pipe. If the mandrill will not pass, that portion of the pipe may need to be repaired as determined by the inspector.
- The contractor shall update the as-built drawing for the property with the location of the beginning and end of the new pipe, connection details and any new appurtenances added (e.g. a clean out to grade). The updated as-built drawing shall be provided to the inspector at the final inspection (647 – Sewer Final; 648 – Storm Final).
- For deficiencies (e.g. ovalization, ponding, kinks and wrinkles), the contractor shall make the Owner aware of the deficiencies and increased maintenance risk they pose. A written copy of such notification shall be provided to the inspector at the final inspection (647 – Sewer Final; 648 – Storm Final).