City of Castroville Water Line Replacement

In 2021, the City of Castroville was experiencing frequent main breaks on old asbestos cement water mains along Lafayette Street south of US 90. Typically, when pipeline breaks occur, valves in the water mains make it possible to isolate small segments to perform repairs. However, existing valves near Lafayette Street were not functioning properly, so the City was faced with having to close valves far outside the affected area to shut down the main for repairs, which would impact numerous customers.

As an alternative to the major shutdown, the City considered installing insertion valves to isolate sections of the water mains to make repairs. As the Consulting City Engineer, our team reviewed the proposed budget and location for the insertion valves. Due to the size of the area experiencing main breaks and the water main network, a significant number of insertion valves would have been required to effectively isolate the area in the event of a future main break. After reviewing the City’s proposed plan for the insertion valves, our team recommended a main replacement project to replace the failing pipe altogether and address the system isolation issues at the same time.

While tackling both issues simultaneously with the replacement project was ultimately more cost-efficient, it did present a new challenge due to space limitations. The existing right-of-way was only 40 feet wide, and in addition to the water main, it included buried gas, telephone, and sanitary sewer. Because the other utilities were present in the same corridor, replacing the water main in a new alignment within existing right-of-way would have required a variance to the Texas Commission on Environmental Quality (TCEQ) rules on separation distance between water and sewer lines. If the variance was not granted by TCEQ, the existing sewer main would have to be upgraded to a pressure rated pipe, but the existing pipe was in good condition and did not need to be replaced.

To avoid the need for a TCEQ variance or a significant increase in the construction budget to replace the sewer main, our team developed an alternate bid to replace the main via pipe bursting. As a trenchless technique, pipe bursting minimizes the impacts of construction, making it particularly useful in urban environments like Lafayette Street with space constraints. It also takes advantage of the existing water main alignment, avoiding separation distance issues with the sewer main that would have occurred with a new open cut alignment.

At bid time, pipe bursting was determined to be the best replacement method for the City and was accepted for construction. Temporary water mains were installed to maintain service to residents, and insertion valves were included at key locations to maintain service to the rest of the City. The approach avoided approximately $300k in sewer replacement costs and replaced approximately four blocks of the failure-prone water main.