The Problem -

Our client's, development and engineering facility relied on a more than 30 year old sanitary wastewater treatment system. The system was failing due to age and threatening to release untreated sanitary wastewater to a nearby stream. Permitting, design and installation of a replacement 60,000 gpd system was required.

In addition to maintaining compliance with the surface water discharge permit to the nearby stream, our client also required a sanitary wastewater treatment system that was cost effective, simple to operate and consistent with their corporate and environmental sustainability strategy.


Our Solution

Roux Associates worked with the client's team to integrate their wastewater treatment needs and sustainability vision to design an innovative constructed treatment wetland system. This was an integrative process that included alternatives analysis, preparation of a white paper, value engineering and regulator education. Ultimately, the constructed wetland system met our client’s objectives by providing a sanitary wastewater treatment system that:

  • Provides effective treatment;
  • Is low energy;
  • Is simple to operate and maintain;
  • Saved $1MM in capital costs and $20,000/year in O&M costs compared to a traditional batch reactor system;
  • Utilized certain existing components of the wastewater treatment system to save costs;
  • Is a passive “green” technology that utilizes wetlands plants;
  • Provides additional green space at the facility;
  • Provides a “demonstration” system that other client facilities can use as a model;
  • Reduces the overall volume of wastewater generated through evapotranspiration by wetlands plants.

Roux Associates obtained a NPDES WQM Part II Permit Modification for replacement of the existing treatment units (settling tanks, extend aeration and clarifiers) with a 60,000 gpd constructed treatment wetland. A detailed engineering design and construction bid package were then prepared for the constructed treatment wetland system including civil, mechanical and electrical drawings/specifications. Key features of the CTW system include:

  • Septic tanks for solids removal;
  • Inflow distribution system;
  • Two vegetated, enhanced aeration, subsurface flow constructed wetland cells;
  • Outflow distribution system; and
  • Alternative discharge to an existing chlorination/dechlorination unit or an experimental disinfection constructed wetland cell.


The constructed treatment wetland system has been installed to allow for future expansion via additional treatment cells and/or a phytotechnology plot. Additional treatment cells and/or a phytotechnology plot may aid our client in meeting future wastewater demands, meeting more stringent discharge standards and reducing or eliminating treated wastewater discharge to the nearby stream. This system allows our client to meet current regulatory and facility needs while helping meet sustainability goals.