The City of Irving’s Cottonwood Valley Golf Course Wastewater Improvements

This project concerns approximately 7,200 linear feet of existing 21-in. to 24-in. wastewater main in the City of Irving, Texas. The main is proposed to be upsized to 30 in. to accommodate build-out conditions per a Wastewater Master Plan. However, the location of the main primarily within a private golf course meant that construction would be tricky. Additional site-specific coordination and constructability challenges also affected the potential replacement options. The original main was constructed in 1969 of vitrified clay pipe. An alignment study determined that no good possibilities existed for realignment around the golf course. A condition assessment indicated various defects throughout the study limits, with the most significant concentrated in two areas: one within the golf course and another outside the golf course proper. Evaluation of current flows by City staff indicated that although the Master Plan calls for upsizing, the existing pipeline has adequate capacity for the foreseeable future. Therefore, two separate packages were developed to address the pipeline segments with significant defects, with the remaining portions left as-is, thereby extending the service life of the pipeline assets and reducing immediate capital costs. The first package involved a 2,320-linear foot stretch with significant defects within the golf course. Because the existing pipeline has adequate capacity for the foreseeable future, the City elected to perform cured-in-place pipe (CIPP) rehabilitation, which substantially reduced the impacts to golf course operations in comparison to open cut replacement and to trenchless replacement options, such as pipe bursting. To further reduce impacts, the rehabilitation occurred during the winter. Additionally, the City elected to utilize BuyBoard, a purchasing cooperative, to contract the work, which reduced costs associated with bid and construction administration. The second package involved a 1,600-linear foot stretch with significant defects outside the golf course proper. Though not impacting play on the golf course directly, this portion had its own challenges. The existing pipeline meandered through a wooded environmental learning center operated by Irving Independent School District on land owned by Dallas County Community College District. To minimize impact to the learning center, the replacement pipeline was aligned along the golf course’s maintenance road, which lay between the wooded area and a pond, roughly parallel to a raw water line owned by Dallas County Utility and Reclamation District (DCURD) which was unable to be located in the field. Additionally, the project involved bored crossings below a bridge and past a forested wetland. The success of this phase was due to collaboration among the City, engineer, contractor, and various affected parties.