The City of Springfield, MO (City) has engaged HDR and WCS Engineering to evaluate, optimize and prioritize sanitary sewer overflow (SSO) remedial alternatives for the Springfield collection system.
This presentation will provide the audience and industry with the following key takeaways:
• Demonstrate how formal optimization software can be applied to prioritize large and complex capital programs including conveyance projects, storage facilities, inflow and infiltration (I/I) remediation, and treatment plant upgrades.
• Illustrate how approximately 75% of SSOs can be eliminated within the first 45% of capital expenditure in the case study example.
• Provide a framework for other city’s to optimize and prioritize SSO remedial measure plans using a best in practice approach to apply intelligent algorithm optimization.
Optimization runs were completed for a range of level of service targets. The relationship between cost and level of service is shown in Figure 1. This figure includes results from optimization scenarios that only include conveyance and treatment expansion options (“Conveyance-Only”), and from optimization scenarios that include conveyance, storage and I/I reduction alternatives (“All Alternatives”). Figure 2 shows an example solution layout map for an optimized solution.
Prioritization of the capital program demonstrated the sequence of implementation that maximized return on investment (ROI). ROI was quantified based on maximizing the reduction in frequency and volume of overflows at the least cost. An example of the prioritization results is shown in Figure 3 with the ROI curve shown in Figure 4, demonstrates that the prioritization is achieving approximately 75% compliance at 46% of the total capital expenditure required to achieve 100% compliance.
The Springfield optimization and subsequent prioritization analysis delivered the following outcomes for the City:
• Supports the City’s Integrated Planning Efforts to deliver best “bang for the-buck” when faced with budgetary constraints.
• Minimizes capital and life-cycle costs required to achieve compliance.
• Prioritizes the investment schedule to maximize the reduction in overflows at each stage of capital investment.
• Enables the City to tackle manageable pieces of the overall solution.
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