Canyon Lakes Sanitary Sewer Interceptor Condition Assessment and Rehabilitation
The Canyon Lakes Sanitary Sewer Interceptor serves northwest and northeast Lubbock and is one of the major interceptors in the City's sewer collection system. The main consists of approximately 43,600 LF of 24- to 30-inch diameter gravity pipeline located almost entirely along the historically sensitive Canyon Lakes System. The City had experienced overflows and infiltration as the interceptor had surpassed its design life and in response, Lockwood, Andrews & Newnam, Inc. (LAN) was selected to perform a condition assessment and design of improvements for the 45 year old pipeline.
LAN led a team through system inspection and assessment. A comprehensive inspection and assessment effort identified pipe condition, blockages, defects, changes in pipe material and locations recommended for cleaning. However, it was determined that a significant portion of the existing pipeline could be utilized in the future, contingent upon on a strategic diversion of flow and the ability to employ a wide-range of rehabilitation and replacement techniques.
As a result, following assessment design was pursued in two phases for improvements to roughly 12,100 LF of the system. Strategies included open cut replacement, auger boring, and cured-in-place-pipe (CIPP) rehabilitation. This approach reduced both cost and impact throughout the Canyon Lakes area, which has historic and pre-historic deposits, extensive recreational park use, and is home to significant Lubbock destination spots.
At a glance
Selective rehabilitation of critical segments resulted in an estimated $5 million in savings to the City
Selective and trenchless rehabilitation reduced the surface impact through sensitive archaeological areas by 85%
A multi sensor condition assessment reduced the potential improvements from 43,000 LF originally planned to just over 12,000 LF, a more than 70% reduction
Rehabilitation included open cut replacement, auger boring, cured-in-place-pipe, point repairs, heavy mechanical cleaning and manhole rehabilitation
To minimize surface impacts, existing manholes were rehabilitated with fiberglass inserts, effectively installing a new manhole within the existing
At ultimate build-out, the Canyon Lakes Interceptor will convey peak flows of almost 10 million gallons per day, serving more than 30,000 people
Because the project area is known for both pre-historic and historic occupations, extensive coordination with the Texas Historical Commission was required through design
Improvements included crossings of two railroads and several TxDOT roadways
To foster better competition in bidding (and thus better pricing), construction was pursued in phases with like technologies bundled together
The interceptor travels adjacent to most of the Canyon Lake System, which is one of the most scenic areas of Lubbock and is used extensively for outdoor activities including city festivals, golfing, biking, fishing, disc golf and general recreation
Coordination at the outset of design with the Texas Historical Commission was critical to maintaining schedule and minimizing the risk for construction delays if artifacts were found
Archeological investigation during the design phase included a pedestrian survey of all proposed improvement locations in addition to 18 backhoe test trenches and four shovel tests. Efforts concluded with no significant artifacts discovered
Pipeline Design, Assessment & Rehab