Plano, Texas embarked on a mission in 2015 to rehabilitate more than three miles of reinforced concrete pipe (RCP) After a condition assessment had shown deterioration due to corrosion from H2S (hydrogen sulfide) sewer gas. The pipeline is in proximity to the White Rock Creek and Prairie Creek areas in the Trinity River watershed. Roughly half of the lines also ran through Gleneagles Country Club, which is considered one of the top golf courses in the Dallas-Fort Worth area. Rehabilitation was necessary to prevent failure of the critical line segment, especially since failure would require tearing up the golf course to fix them.
The City partnered with engineering firm Halff & Associates to design a solution to the pipe corrosion problem. Halff recommended cured-in-place pipe (CIPP) rehabilitation to repair the existing wastewater lines. Other options, such as sliplining, were also considered. Sliplining was ruled out due to the amount of flow capacity that would be lost as a result of a large reduction in the inside diameter. In addition, the number of bends in the pipeline were not ideal for a sliplining solution.
“We chose CIPP due to the minimal disruption it would cause to the environmentally sensitive White Rock Creek area, said Shahrzad Tavana, senior engineer with the City of Plano.
As low-bidder on the project, Insituform was chosen in August 2016 to do the work using its flagship CIPP process. Insituform is the originator of the CIPP process, with its first installation taking place in the United Kingdom in 1971. Worldwide, the company has installed more than 30,000 miles of CIPP to date.
“We felt comfortable choosing Insituform as the contractor based on its longevity in the industry and recommendations from neighboring municipalities,” added Tavana.
According to the City, the work was performed at two locations generally identified as White Rock Creek and Prairie Creek due to the pipeline’s proximity to the two creeks. The White Rock Creek portion of the job ran from Spring Creek Parkway to Plano Parkway and consisted of approximately 16,300 ft of 24- to 36-in. sanitary sewer interceptor. Adjacent to this first portion was 1,000 ft of an 18-in. sewer main running parallel to Plano Parkway, 450 ft of 15-in. sewer main and another 150 lf of 15-in. sewer main. The Prairie Creek portion of the project consisted of approximately 2,500 ft of 21-in. sewer main located along the banks of Prairie Creek and continuing downstream. In total, the project included 19,984 ft of sewer main rehabilitation.
About half of the project ran directly through the exclusive Gleneagles Country Club. Work running through the club’s 36-hole golf course brought a number of challenges. First, two special access roads had to be built for equipment access in order to prevent damage to the greens and fairways. Additionally, most of the work had to be done within a six-month period due to the requirements of the golf course.
Other tricky setups included non-conventional pipe dispersion structures running under a drainage channel and location of manholes next to tee-boxes on the golf course. The clean and TV (CCTV) company, Nezat Training, cleaned up to 5,000 ft at a time directly next to golf course without having to be on the premises.
In addition to the challenges presented by work on the golf course, the contractor also had to deal with three separate HOA groups, work delays due to rain and had to coordinate with a North Texas Municipal Water District Lift station.
Insituform received a notice to proceed on Oct. 25, 2016, with an agreement that the work would be done within 300 calendar days. The golf course work could only be done during the off-season from November to February, with allowances for restoration and other minor items up through March and April. The contractor completed the rest of the work within the allowed timeframe by mid-2017.
Before the work could proceed, the line had to be completely bypassed. Running straight through the golf course, the bypass was anchored off next to the creek in order to keep it out of the fairway. Bypass work was done by Maverick Pump.
Once the bypass was setup, the CIPP tubes were wet out at an Insituform facility in McGregor, Texas. The tubes were kept in a refrigerated truck for the two-hour drive to prevent premature exotherm and delivered straight to the jobsite for installation.
Accessibility on the jobsite was the primary issue for completing the job in the allowable time and making sure that all stakeholder concerns were addressed. In addition to access roads capable of supporting fully loaded 18-wheel tractor trailers, the contractor had to build a scaffold system from an adjacent road off the side of a bridge at two separate locations due to limited access. This helped the crew perform an installation on a concrete lined drainage channel on the golf course as well as an installation off a bridge adjacent to one the busiest streets in Plano. Another installation shot required manhole access in a bunker on the 18th green of the Queens Course.
Gleneagles Golf course was playable for the entire project duration. Minimal restoration of the golf course was required and performed by a subcontractor that had develop a working relationship with the golf course over the years. The City of Plano and Gleneagles Golf course were pleased with the effort provided by the engineer and contractor to minimize adverse impacts during construction. The entirety of the project was completed in 22 separate installation shots, most of which were installed using the traditional water inversion water-cure installation process. Four of the lines were rehabilitated using Insituform’s air-inversion steam-cure (AISC) method. This method helps cut down on water usage and provides a quicker cure for shorter segments. While many of the shots measured more than 1,000 ft in length, the longest installation run on the project ran more than 1,500 ft. Rehabilitation of the access manholes using CIPP was performed concurrently with the Insituform CIPP installations by Infrastructure Rehab USA out of Shreveport, Louisiana.
The project was completed ahead of schedule by mid-summer 2017. The bypass was removed and the lines were back in service shortly thereafter. The success of this project was predicated on the ability to manage risk associated with providing the appropriate rehabilitation method along with sufficient installation access while mitigating impact in a difficult golf course location.
The project is a prime example of the success that can be realized, even on difficult projects, when the owner, engineer and contractor work together throughout all phases.
“The project challenges were unique, but what amazed me was how all of the stakeholders on this project came together in a spirit of cooperation to make this project a success,” said Tony Almeida, P.E., Halff & Associates.