San Antonio Water System Turtle Creek Transmission Main Pipeline

The Medical Center, located in northwest San Antonio is home to major medical institutions and medical offices in a highly developed urban area. To provide redundancy to the Medical Center area, a new water transmission main was needed.

This project consisted of the design of 4,725 linear feet (LF) of 42-inch water transmission main. The pipeline was primarily installed via open cut methods within easements on private property, with two trenchless crossings of Datapoint Road and Fredericksburg Road totaling approximately 480 LF.

As the prime consultant to SAWS, our team provided design phase services for the water main. The design included route analysis, existing utility research and coordination, material selection, and sizing and locating of air release valves and multiple tie-ins with existing pipelines. KFA also provided bid and construction phase services, including contract administration, site visits, submittal reviews, construction meeting, and RFI/CO review and response.

One primary challenge was the route analysis. The project area has been developed for over 30 years, with several apartment complexes and commercial high-rise buildings in the project corridor. The team evaluated route options and prepared preliminary alignments for the pipeline. One alignment was located predominantly in public right of way of Fairhaven and Datapoint Road, while the second alignment primarily ran through private property in new easements. The public right of way option was challenged by several apartment complexes and condominium associations along the route without alternate access to the public right of way as well as multiple conflicting utilities in the roadway. Our team recommended the private property option, obtaining easements from property owners to avoid the risks and costs associated with installation in the public right of way, an approach that saved SAWS approximately $2 million by avoiding required utility relocations and slower production rates associated with traffic to the numerous apartment complex entrances.

The tie-in to the existing 20-inch water main in Datapoint Drive was challenged by the conflicting location of an adjacent 12-inch asbestos cement water line. Our team evaluated existing valve locations and proposed a 12-inch valve insertion to limit the shutdown and avoid impacts to customers. This approach allowed for the relocation of the 12-inch main in conflict to complete the tie-in.

Another challenge concerned a stretch of easement approximately 700 feet behind an apartment complex. The available space is narrow, and access was constrained to the east and west ends. In addition, existing water and electric utilities conflicted with the proposed alignment. Our team designed a relocation for the 6-inch apartment water service line and prepared an allowance bid item for the relocation of the apartment complex’s three-phase underground electrical service, successfully mitigating the conflicts during design and avoiding any conflicts in construction.

The project was completed with just $6k in change orders for unforeseen conditions, less than 0.10% of the original bid. The new water main provides significant redundancy in system capacity for a critical portion of the community.