Unique Partnership Salvages Sewer Rehab Project

City’s partnership with oil company opens a path for complicated sewer line rehabilitation project without compromising production schedule.
Unique Partnership Salvages Sewer Rehab Project
Will Giebel operates a CUES camera controller with POSM video software while inspecting a sewer line.

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The Ponca City (Oklahoma) Environmental Services Department is well-versed in wastewater issues, but working in an oil refinery stretched its comfort zone.  

Ponca City is a community of 26,000 built on the fortunes of the oil industry. While its economy continues to diversify, many of its citizens work to refine crude oil. When a 100-year-old sanitary sewer main passing through the center of the Phillips 66 Ponca City refinery complex showed signs of failure, the city leveraged a unique partnership with this industrial customer to solve the issue.

Ponca City is located at the midpoint of three larger cities: Oklahoma City; Tulsa, Oklahoma; and Wichita, Kansas. The city’s Environmental Services Department is responsible for all aspects of municipal wastewater and water operations, as well as solid waste collection, recycling and landfill operations.

The city is located on a predominantly flat drainage basin. The wastewater collections system is composed of 12 sewage-pumping facilities and 177 miles of pipe, ranging from 6 to 30 inches in diameter. The pipes are made of a wide range of materials, from PVC and clay to ductile iron and concrete. PVC is the material of choice for all new construction.

“All wastewater system components are in good to fair condition,” says Hong Fu, Ph.D., director of the city’s Environmental Services Department. “Like most utilities, our greatest challenges involve the age of the system. Portions of the system are almost 90 years old and provide inadequate capacity. Over the past 10 years, we’ve invested $8 million in capital improvement projects to systematically improve the capacity and structural integrity of the system.”

The city also works to battle tree roots, which invade sewer pipes. The department currently uses a professional root control company, which employs a chemical treatment to keep roots at bay.

Relying on staff

In-house crews tackle smaller-scale projects, including leak repairs. They handle smaller construction jobs, as well, usually projects involving less than 100 feet of shallowly buried, small-diameter pipes. Larger projects are completed by outside contractors, through a competitive bidding process.

The department’s equipment fleet includes two flusher trucks (a 2004 Vactor Mfg. jetter truck and 2014 Vactor Mfg. combo unit) and a camera van equipped with an R.S. Technical Services Inc. (RST) sewer camera system and POSM (Pipeline Observation System Management) software.

The entire wastewater service area is divided into 20 sections. A two-person city crew flushes the system on a 2 1/2- to three-year cycle, moving from one section to the next until reaching the end and starting over.

The department uses Lucity software for water and wastewater work orders, invoices and inventory tasks. In the field, workers utilize ArcGIS for mobile mapping, water main break tracking, new waterline installation, valve replacement, sewer line flushing, root control, manhole rehabilitation and unpermitted discharges. The system is currently about 80 percent GIS mapped.

The department prides itself on keeping the city’s wastewater system in good repair. However, one particular length of sewer pipe proved less simple to maintain: a city-owned sewer interceptor that enters the Phillips 66 refinery from the north and exits to the east.

An important interceptor

“This interceptor is an important component in the city’s wastewater collections system,” says Fu. “It serves a fully-developed drainage basin of 570 acres in the southwest part of town.”

During a major rainfall May 19, 2005, the sewer surcharged, causing stormwater mixed with a small volume of hydrocarbons and wastewater to overflow from three manholes.
In response, Phillips 66 retained the engineering firm of Burns & McDonnell to investigate the sanitary sewer system within the boundaries of the refinery. Exactly what caused the hydrocarbons to enter the mix remains a mystery. The Burns & McDonnell report submitted in 2006 revealed no evidence of cross connection between the city’s sanitary sewer and the refinery’s oily wastewater by either CCTV inspection, dye testing or smoke testing.  

“However, the investigation identified significant structural and hydraulic deficiencies in the city’s sanitary sewer interceptor, such as cracks, offset joints, missing pipe segments and an undersized section,” Fu says. “We realized we needed to address these deficiencies within a reasonable time frame to avoid future unpermitted sewer discharges.”

The original interceptor was installed almost a century ago, before the refinery was built. In all, the section measured about 6,900 feet of clay pipe, ranging from 12 to 24 inches in diameter.

Refinery expansion

As the refinery expanded, it installed multiple pieces of equipment and its own refinery wastewater pipes over the top of the existing sewer. The challenge: replacing or rehabilitating the pipe in the middle of an active refinery under extreme space constraints and without compromising the industrial system schedule.

“City management and staff always considered the project to be a major challenge,” Fu says. “We realized straight off that only a collaboration between the city and the refinery would make the project a reality. Phillips 66 was on board with the project from the start and was committed to making it happen in 2015.”

The department met frequently with refinery staff and made multiple site visits to develop a plan of attack.  

“We had to learn each other’s businesses,” says Darwin Haney, water utilities superintendent with the city, who acted as construction inspector on the project. “They didn’t know anything about the sewer business, and we didn’t know anything about oil refining.”

Doing it trenchless

The partners chose a trenchless approach using two methods. Pipe bursting was the preferred method to avoid digging through existing refinery piping. Cured-in-place pipe rehabilitation would be used wherever space constraints prevented pipe bursting. Original pipe would be replaced with new PVC with diameters of 12, 16 and 20 inches.

The project was designed by Cabbiness Engineering. Urban Contractors of Oklahoma City was awarded the construction contract and did the pipe bursting using equipment from TT Technologies. CIPP work was performed by Insituform Technologies as a subcontractor to Urban Contractors.

“City infrastructure projects and refining operation have very different safety standards,” says Haney. “Construction workers on site were required to wear Nomex clothing, and the site was under constant hydrogen sulfide monitoring.”   

The refinery provided all safety training for construction crews and offered a full-time safety officer at its own expense to ensure the construction process would be compliant with refinery regulations.

“The refinery even hired a contractor experienced in refinery construction to dig entry and exit pits for pipe bursting so the holes would be ready when the rehabilitation process started,” Fu says.

The original CCTV inspection indicated extensive infiltration under one of the refinery’s stormwater ponds.  

“We knew the pond had to be drained to reduce the water pressure on the pipe in order to proceed with pipe bursting,” Fu says. “To everybody’s surprise, draining the pond revealed two out-of-service manholes covered with concrete caps that needed to be eliminated as well as an additional 8-inch sewer main that needed to be rehabilitated.”

Concrete solutions

In many cases, pipes were encased in concrete, in all likelihood to protect them as the refinery expanded. That made pipe bursting more challenging.

“The extreme case was a block of concrete that protruded inside a pipe,” Fu says. “That required a water-jet-powered saw and four days of cutting to remove.”

CIPP was used underneath a railroad line and in areas where bends in the pipe were too extreme for bursting.

Haney notes that at a refinery, each part of a construction project must be separately permitted each day, and only one permit is issued to a contractor at a time.

“If you’re pipe bursting in one location and want to start manhole rehabilitation in another, you couldn’t get two permits for two locations,” he says. “As we learned to trust each other, the refinery got to the point where they gave a little and we could work in multiple locations. Mike Paige at Phillips was very instrumental in getting the permits for the project. I also worked very closely with Dale O’Neill, my rep at Phillips. By the end of the project, working day in and day out, we were like brothers.”

The entire project was completed safely in four months while refinery operations continued 24/7.

“The most memorable part of the job was simply finishing everything we’d set out to do on time,” Haney says.

While the original contract was valued at $1.47 million, change orders and pipe diameters differing from the expected size both added and subtracted from the total cost. In all, the project was completed for $1.67 million. The project was honored with the 2014 National Recognition Award by the American Council of Engineering Companies and the 2015 American Public Works Association-Oklahoma Project of the Year Award.

The refinery’s participation not only ensured a smooth and safe construction process, but also resulted in significant cost savings for Ponca City.

“I want to give them full credit,” Fu says. “As part of our community, they really helped us to make the project successful, and the partnership helped to make the job more economical for taxpayers.”

Meanwhile, back at the refinery

After completing a challenging pipe rehabilitation project on the premises of the Phillips 66 Ponca City refinery in 2015, Ponca City, Oklahoma, is currently in the design phase of another major sanitary sewer interceptor rehab project at the facility.

The length of the section to be replaced measures approximately 10,000 feet and represents pipe diameters of 18, 24 and 27 inches.

“The concrete pipe was constructed in 1971 and 1972 and has suffered erosion problems due to acid corrosion,” says Hong Fu, Ph.D., director of the city’s Environmental Services Department. “The project starts at a manhole outside the west gate of the Ponca City refinery’s south tank farm, goes east across the tank farm and Highway 60, and ends at the creek crossing west of the Ponca City wastewater treatment plant.” 

Slated to begin construction in 2018, Fu says this project has the city breathing a little easier: “The pipe isn’t located under any active refinery processing units. That makes life a bit easier.”


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