The Cenex Pipeline Company of Laurel, MT, owns and operates 423 miles of petroleum product pipeline and operates six pipeline terminals in four states.

Cenex retained Braun Intertec to support the design wastewater treatment systems and obtain National Pollutant Discharge and Elimination System (NPDES) discharge permits for tank draws at the six terminal facilities.

Challenges

When the Environmental Protection Agency (EPA) promulgated the revised toxicity characteristic (TC) rule, 25 compounds were added to the list of newly regulated constituents, including benzene, a volatile organic compound present in the petroleum products shipped by Cenex Pipeline. Wastewater (called tank draws), which typically accumulates in the bottom of terminal storage tanks, contained hydrocarbon constituents that became regulated.

Solutions

Our engineers supported the design, construction, and obtained NPDES permits for a relatively inexpensive wastewater treatment system that treats TC waste to acceptable levels. The system was designed as a modular unit that is easily adaptable to variable flow rates and wastewater type. The wastewater treatment system includes uniquely designed components incorporating gravity separation, filtration, stripping, and polishing.

Optional units for control of foaming and oxidation were also designed.

A pilot treatment system was fabricated and installed at the Billings terminal. System components and operations were fine-tuned during the demonstration project, and shortly thereafter, construction of the treatment system and holding pond was begun at the Minot, ND, facility.

One of the advantages of this system is its relatively automated operation, which does not require significant investment of personnel time, an attribute requested by Cenex Pipeline. Because this approach met the requirements for classification as a wastewater treatment unit, Cenex Pipeline was exempted from stringent and costly hazardous waste management standards.