Denver completes jacking of sanitary sewer with HOBAS pipe a mile high, 30 feet down

In the mile high City of Denver, Trainor Construction Co. of Golden, Colo., worked 30 feet below the surface to install 2,800 feet of 45-inch HOBAS centrifugally-cast, fiberglass-reinforced, polymer mortar (CCFRPM) pipe.

May 16th, 2003

May 16, 2003 -- In the mile high City of Denver, Trainor Construction Co. of Golden, Colo., worked 30 feet below the surface to install 2,800 feet of 45-inch HOBAS centrifugally-cast, fiberglass-reinforced, polymer mortar (CCFRPM) pipe.

This was a section of the North Denver Sanitary Sewer, Phase III, a project designed and owned by the City and County of Denver. It is part of more than 8,600 feet of pipe being installed by various methods.

This traditional jacking installation was another demonstration of the advantages of trenchless technology, permitting the installation of underground utilities with minimum disruption to the surface facilities.

Trainor utilized conventional tunneling equipment with which single loads of excavated earth are removed from inside the pipe by the workers in the pipe itself. With the installers' help, the boring head loads dirt into the bucket on a small conveyor belt located directly behind the excavation. Then, when the load is ready to be removed, the workers lie flat on top of the earth, which is trollied out to the end of the pipe where it is removed.

As the tunneling progressed, alignment was checked constantly using a laser while workmen in both the insertion and receiving pits stayed in constant touch with two-way radios.

Tight schedule

The timeline called for the project to be completed before the Mayor of Denver was scheduled to speak at the Martin Luther King monument dedication. This created a critical issue as construction progressed towards City Park. The reliability of HOBAS pipe enabled Trainor to stay on schedule. The standard 20-foot lengths cut production time because there were fewer joints to assemble and fewer pipes to handle. Trainor, that had used HOBAS previously on the Delgany Common Slipline Project, completed another successful run.

High strength

The HOBAS pipe had a jacking load rating of 365 US tons minimum with a pipe stiffness of 265 psi, which were more than adequate to handle both the live jacking loads and the 30-foot cover over the installed pipe.

10 year Hhstory

HOBAS pipe has been utilized on many projects in the Denver area over the past 10 years including nearly every type of installation method:

* The Delgany Common Interceptor, which involved 1,600 feet of 72-inch diameter pipe for the relining of an aboveground interceptor.

* The Clear Creek Rehab, including 1,100 feet of 72-inch pipe for sliplining.

* The Denver Airport, utilizing 1,300 feet of 48-inch, 400-ton jacking pipe for an industrial waste line.

The municipalities projected a long service life for the CCFRPM pipe and they pointed out that typical concrete piping corrodes from sewage while the new HOBAS pipe will not. Judging by Denver's enthusiasm for this successful trenchless installation of HOBAS pipe, there will be many more to follow.

Denver used the Internet to explain a number of details of the North Denver project. For more information visit: http://www.denvergov.org/WMDDesign/template22667.asp.

HOBAS pipe is manufactured in sizes from 18 inches to 102 inches in pressure and non-pressure classes. For more information, please contact HOBAS at 800-856-7473, 281-821-2200 or e-mail at info@hobaspipeusa.com. Facts are also available at www.hobaspipeusa.com.


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