Client Trinity River Authority of Texas

Bear Creek Interceptor System

Grand Prarie, TX

The Trinity River Authority retained LAN to perform a condition assessment, as well as a preliminary design report, for approximately 5,000 linear feet of the Bear Creek Interceptors. These sewer interceptors consist of a 54-Inch line constructed in the early 1970’s and an 84-Inch line constructed in the late 1990’s. The pipes run largely parallel to each other, are interconnected with 5 large diversion structures and have two siphon crossings of Bear Creek.

The condition assessment was based on review of CCTV, surface inspection and penetration testing for the sewer line and sonar profiling of the underwater siphons. Each section of pipe, manhole and junction structure was assigned a condition grade rating ranging from “excellent” to “immediate attention”. Ten of the 16 sections of pipe were graded with the highest defect grade rating, requiring immediate action, due to visible reinforcing steel. These findings were presented in a standalone condition assessment report.

Following the submittal of the condition assessment report, several workshops were held in order to discuss potential rehabilitation methods/strategies. These workshops led to the development of five separate alternatives which employed several different rehabilitation methods including CIPP, sliplining and open cut replacement. These alternatives were evaluated and consideration was given to temporary impacts, permanent impacts, construction risk, constructability, ROW requirements, and cost. This information was compiled and submitted in the preliminary design report.

At a glance

54- to 84-inch sanitary sewer interceptors

10,000 LF condition assessment

110 million gallons per day service capacity

Condition assessment of two siphons

Condition assessment of five junction boxes

Designed to provide capacity through 2060


Five rehabilitation alternatives evaluated

Trenchless rehabilitation technologies considered

Designed for long term system maintenance and operability


Condition Assessment

Pipeline Design, Assessment & Rehab

The Trinity River Authority of Texas was created in 1955 and serves more than 60 cities in the Trinity River basin