South Sanitary Sewer Interceptor Replacement

South Sanitary Sewer Interceptor Replacement

Project Manager

City Engineering / David Barth, P.E.

SUA Project No. 16SG02

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What We're Doing

The City of Stillwater and Stillwater Utilities Authority is replacing the South Sanitary Sewer Interceptor (SSSI), two creek crossings, rehabilitating the Foxfire Lift Station, and abandoning the Squires Landing Lift Station. 

Anticipated Milestones

  • Anticipated Date (Design): FY20
  • Anticipated Date (Construction): FY22
  • Anticipated Date (Completion): FY24

Benefits of the Project

The South Sanitary Sewer Interceptor (SSSI) immediately upstream of the Waste Water Treatment Plant is a combination of 42 inch and 36 inch diameter reinforced concrete pipe. Video inspection of the SSSI shows significant deterioration that contributed to a pipe collapse in 2015. Rehabilitation of the Foxfire Lift Station and abandonment of the Squires Landing Lift Station will improve our system efficiency and reduce operational expenses.

Budget & Funding

  • Year Funded: FY2017
  • Funding Source: Wastewater Fund
  • Project Budget: $400,000 for design
  • Expenditures to date: $251,000

Project Management


June 26, 2017: Tetra Tech has been selected for design services and project scope is currently being developed.

October 18, 2017: Data is currently being collected using flow monitors and the design will continue through the summer of 2018.

February 27, 2018: Engineering firm, Tetra Tech, is currently evaluating design alternatives.

June 18, 2019: Project was on hold due to other capital improvement priorities. Study phase will start again in July.

November 14, 2019: The City received Preliminary Engineering Report with recommended alternatives. Preliminary design will begin in December 2019.

February 25, 2020: Preliminary Design is underway and 65% drawings are expected in March, 2020.

April 23, 2020: Preliminary Design is complete. Final design, easement acquisition, and an environmental study will begin soon.

May 29, 2020: Geotechnical investigation at eight sites along the proposed interceptor alignment will begin once the weather is consistently dryer. 

September 1, 2020: Geotechnical investigations are complete and Tetra Tech is progressing on the Environmental Impact Document.

November 25, 2020: Work continues on the Environmental Impact Document and Categorical Exclusion Document for the Oklahoma Water Resources Board loan process.

February 18, 2021: The OWRB is currently reviewing the Environmental Impact Document while the Engineer continues to refine the design of the sewer interceptor. 

April 8, 2021: The City Council and SUA have authorized the CWSRF loan application with OWRB. The Environmental Impact Document is complete and a public meeting is scheduled for April 21,2021.

September 14, 2021: Staff are currently reviewing the 90% design plans submitted by Tetra Tech.

October 4, 2021: Easement acquisition phase is underway. City Attorneys Office is currently reviewing easement documents. 

Actions Authorized by Stillwater Utilities Authority (SUA)

  • 10.2.17  | SUA-17-34 |  Professional Services Agreement

  • 03.1.21  | SUA-21-08 |  Resolution for Loan



(Sewer trunk line showing heavy erosion)

View looking inside sewer 36 inch trunk line showing loss of mortar.