Burgess & Niple (B&N) led a multi-consultant team that evaluated alternatives to address inflow and infiltration (I/I), structural concerns and the long-term sustainability of the sanitary sewer system within the West Fifth Avenue study area. The team identified the locations and pathways of excessive I/I and prepared a Business Case Evaluation (BCE) for the recommended improvements. B&N’s BCE addressed status quo (no improvement performed), risk cost, environmental cost, total 30-year net present value, and benefit-cost ratio.
The project included an evaluation of green improvements. This included rain barrels, bioretention swales, pervious alleys, and pervious concrete curbs and gutters for a 10-year, 6-hour storm event. The evaluation was conducted to determine if there were feasible green alternatives to upsizing storm sewers to address the additional runoff in the study area generated by the sanitary sewer rehabilitation.
Project components included:
- I/I remediation
- CCTV sewer inspection
- Field investigation
- Green infrastructure evaluations
- Community outreach
- Weighted Criteria Matrix Analysis
- Alternatives Development
- Preliminary 30% Construction Plans
At the completion of the project, the B&N team provided the City of Columbus Division of Sewerage and Drainage with a detailed report of the findings and a cost/benefit analysis. The final recommendations include a combination of sewer and manhole rehabilitation, relief sewers, and sewer replacement projects, prioritized to solve I/I and structural problems in the area in the most cost-effective manner.