Plagued by frequent backups, multiple broken and missing pipe segments, and large amounts of groundwater inflow and infiltration, the 100-year old sanitary sewer main located through the heart of the Phillips 66 Refinery in Ponca City, Oklahoma was in dire need of repair. For decades city leaders, refinery management and vocal citizens bemoaned that a sensible and affordable construction solution for this sewer project could not be designed.  As the owner, the City of Ponca City, Oklahoma contracted with Cabbiness Engineering, LLC to evaluate the nearly 6,700 linear feet sanitary sewer main to come up with functional and feasible solutions.  With the additional constrictions of the sewer main being located within an oil refinery operating at full capacity - 24 hours a day, 7 days a week - the design had to take into account the refinery’s stringent safety requirements and operational restrictions that construction would encounter.

In order to provide the most effective, cost-efficient engineering design for all parties involved, Cabbiness Engineering evaluated several design alternatives and construction methods involving trenchless rehabilitation (Pipe Bursting, Slip Lining, and Cured-In-Place Piping), open cut trench and direct bury pipe, as well as a sewer lift station bypassing the refinery entirely. Based on conclusive design calculations and field verifications, an innovative trenchless rehabilitation appraoch that combined the use of pipe busting and cured-in-place was utilized.

Other design and construction challenges associated with this project included:

• Stringent Phillips 66 Refinery safety requirements, as well as coordinating various field personnel to establish viable construction sequencing with regards to the refinery’s around the clock operations.

• Coordinating with BNSF Railroad engineers to rehabilitate the sewer pipe segment located beneath the railroad inside the Phillips 66 Refinery property.

• Several points of continuous water inflow and infiltration  (I&I) estimated at 100 gallons per minute.

• Numerous unknown refinery piping conflicts, inaccessable manholes and other sewer pipe obstructions.

Despite the many project challenges, our team was able to delivered this $1,700,000 dollar project within budget and within the aggressive 4 month construction schedule.  Upon project completion, our team was able to show the refinery a $254,000 annual savings in sewage billing and the undetermined cost saving of not continuously replenishing water lost from their fire water storage ponds.