APWA's Texas Chapter names SH 144 - Lake Granbury Storm Sewer Outfall Replacement Project of the
About the Project
This emergency repair project arose out of a torrential rain event that hit the City of Granbury in 2015. The storm overwhelmed local storm sewer systems, causing an old corrugated metal pipe which drained into an unnamed stream and a significant portion of the city had gradually corroded and failed.
The storm inundated the pipe, causing it to separate and erode quickly into a 35-foot deep sinkhole that was nearly 50-feet in width.
The sinkhole opened immediately beneath a City of Granbury lift station, causing the lift station to shift, separate from its related service lines, and ultimately wash out towards Lake Granbury. City crews discovered the sinkhole at approximately 3:00 AM on the morning of May 10th, and were able to secure the area and set up a perimeter to maintain the safety of the site.
In addition to draining a large portion of Granbury, the corrugated metal pipe served as a significant drainage outfall structure for State Highway 144 in Granbury. While the site was in this condition, all rainfall events still drained through the washout area, and site drainage cascaded down the face of the exposed slope, threatening additional material loss, potentially jeopardizing the retail structure within 25-feet of the failure zone.
Subsequently, the Texas Department of Transportation (TxDOT) engaged CP&Y, Inc. to develop plans to repair the sinkhole on an emergency schedule. CP&Y met on-site with City, TxDOT, and Brazos River Authority staff to scope the situation and path forward. CP&Y was given less than three months from Notice-to-Proceed to survey, design, develop and finalize construction plans for the project to meet the final plans submittal date stated in the contract, July 22, 2016. CP&Y delivered final plans ahead of schedule on July 14th.
Members of our project team, including our clients, the TxDOT Stephenville Area Office and the City of Granbury, attended the TPWA's Annual Conference in Fort Worth on June 28th to accept the award.