- Approximately 1,905-ft of 32-in diameter high-density polyethylene (HDPE) pipe was installed underneath Lady Bird Lake utilizing horizontal directional drilling (HDD)
- Located beneath parkland with trail network and dense urban center
- HDD pathway with compound curve designed to avoid existing utilities while staying within easement limits
- Subsurface conditions include Austin Group, Buda Formation & the Del Rio Formation
- Services provided: preparation of Geotechnical Baseline Report, pipe selection and construction management support
The reclaimed water system extension is a key improvement to the existing system located within downtown Austin. Overall, the project is comprised of about 8,000 linear feet of 8-, 12-, 24- and 32-in diameter pipelines. To cross beneath Lady Bird Lake, approximately 1,905-ft of new 32-in diameter high-density polyethylene (HDPE) pipe was installed via horizontal directional drilling (HDD) techniques while the remainder of the line was constructed using open-cut methods.
The HDD component of the project begins just south of W. Riverside Drive extending north beneath Lady Bird Lake and continuing along San Antonio Street, terminating north of West 2nd Street. Due to the limited pipe layout space, the HDD rig was relocated to the exit location along San Antonio Street to pull the new HDPE pipe from the north end of the project. The limited space required a mid-pull pipe fuse complicating the project even further. Additionally, the strict entry and exit locations required a compound curve in the path design to avoid utilities and as well as stay within City easements.
Brierley provided recommendations during the geotechnical investigation, designed the HDD path, provided a geotechnical baseline report (GBR), provided the pipe calculations, and assisted with the construction management services.