Jollyville Water Transmission Main
Austin, TX

Jollyville Water Transmission Main | Austin, TX

This project involved the design and construction of a water transmission main from the City of Austin’s Water Treatment Plant No. 4 to the Jollyville Pump Station.  This project consisted of the design and construction of 35,000 feet of 84-inch water transmission main installed in a 10-foot diameter tunnel (nominal), including ancillary connections and valves. Due to operational requirements, the project passes through the northern Edwards Aquifer Recharge Zone and under the Balcones Canyonland Preserve (a 24,000-acre nature preserve created within suburban Austin, set aside for protection of native species, and having no public access).  Because of the significant public scrutiny and sensitive environmental concerns, the design team had to carefully examine both public issues and environmental constraints, balancing alignment decision-making between minimizing environmental impact and accommodating public input and approval. Initially the team evaluated 10 alternative route designs (including open cut and tunnel excavation options), finally resulting on an “all tunnel” alignment, ranging from 100 to 350 feet below the ground, fully avoiding any impact to either protected/endangered species or characteristics of groundwater sources for local springs and creeks.


During design phase, CAS prepared the preliminary engineering study and provided design services for this project, which included development of Basis of Design tech memos, system schematic, hydraulic profile, shaft site plans and piping layout, tunnel plan, and profile. CAS also was responsible for conducting an alignment study to develop alternative conceptual alignments and assess community, cost, engineering, construction, regulatory, and environmental factors for each alignment alternative.

During the construction phase, CAS performed as Resident Project Representative charged with ensuring quality assurance and compliance with the Contract Documents. This role included geologic mapping; analysis of contractor quality and reporting of non-conformances; monitoring overall contractor progress, quality and safety performance; response/support to RFIs and Claims/Change Orders; and coordination of third-party independent materials testing to make certain all work was accomplished to the intent of the engineer-of-record. During construction phase, CAS was responsible for the construction oversight for the project and served as Owner representative, ensuring CMAR quality control and compliance with the contract documents. CAS performed the inspection / oversight of all construction activities for the project / task acting as representative of the Owner to ensure quality control and compliance with the intent of the engineer-of-record.

Project Cost: $86M

Owner: City of Austin