Engineered Solutions

W-1 Leon Creek

05 October 2023

Engineered Solutions: W-1 Leon Creek

Pape-Dawson provided planning, design, and construction phase services to deliver the W-1 Leon Creek sanitary sewer project- a 4-mile regional gravity wastewater outfall to serve customers and to provide the San Antonio Water System (SAWS) the ability to convey approximately 106 MGD (million gallons per day) within its western sewershed.

W-1 was part of the SAWS Consent Decree compliance program and provided the elimination of a historical Sanitary Sewer Overflow (SSO) location. The project involved the replacement of an undersized and aging 42″ and 54″ concrete outfall with a 72″ and 84″ fiberglass outfall within the Leon Creek floodplain, across both the City of San Antonio (CoSA) and TxDOT roadways, and through COSA and  Bexar County Parks. The project involved easement acquisition and coordination with SAWS, CoSA, Bexar County, and private property owners.

The location of the project called for unique construction methods and extensive coordination. Construction activity within the Leon Creek floodplain required tunneling/boring under Leon Creek for long stretches. The design also involved several road crossings and coordination with both CoSA and TxDOT. Trenchless construction was utilized to successfully install an 84” main beneath portions of SH 151 and the lower segment of the project required a large tunnel to avoid deep open-cut segments through Rodriguez Park and under Leon Creek.

Another important challenge the team faced was ensuring the system remained operational during the construction of the new main. The team proposed an extensive bypass pumping plan and construction phasing to accomplish this and allowed for uninterrupted service to SAWS customers.

Pape-Dawson utilized a polymer concrete manhole with integrated stop logs to temporarily divert sewer flows until the SAWS W-6 project was completed. The use of the stop logs minimized the risk and cost to SAWS associated with a large-diameter bypass pumping system and minimized impacts  to the recently completed CoSA parks Leon Creek trail system. Our services also included relocating underground utilities and coordinating geotechnical, environmental, and surveying services to further evaluate the existing wastewater main alignment.

The project was completed per plans with minimal design-related change orders. The use of the polymer concrete manhole and integrated stop logs worked flawlessly as designed, which allowed for a smooth connection to the adjacent SAWS W-6 project and increased accessibility and efficiency for countless San Antonio communities.

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