- Sanitary Sewer Facilities Plan
Burns & McDonnell was engaged by the City of Pierre, S.D., to conduct an evaluation of the existing sewage collection and treatment system and to prepare a 30-year master plan for improvements to the system. The study was conducted in two phases. Phase I generally consisted of an inventory and assessment of the trunk sanitary sewer system, modeling the trunk sanitary sewers, identifying current bottlenecks, development ordinance review and a 30-year expansion plan.
Growth projections were developed in coordination with the city planner to properly address in-city development and potential annexation areas through buildout.
- Collection system condition survey
- GIS/mapping update
- Hydraulic modeling
- Ordinance and rate structure review
- Prioritized recommendation of capital improvements
Established manhole inspection and inventory forms are linked to the geodatabase, with mapping and database information generated for trunk sanitary sewer lines 10-inches and larger. The overall system has approximately 1,200 manholes. A hydraulic model, XP-SWMM, was then used to analyze current and future flows and plan recommendations for the 30-year planning horizon. Appropriate design criteria for peak wet weather flows were developed in coordination with the city staff, and flow estimates were developed based on the existing population and land use, city design criteria, and lift station and plant influent records.
The recommended capital improvements program is designed to optimize available funding and/or utilize additional funding mechanisms. Opinions for probable construction costs and review of the city’s existing ordinance and rate structure were included. The plan addresses treatment plant expansion, relief sewers, extension sewers, lift stations and system rehabilitation.
Phase II assisted the city in completing flow monitoring, inventory and analysis of additional sanitary sewers, additional modeling, GIS services, wastewater plant evaluations, rate structure evaluation and design services.