Johnson County Wastewater (JCW) optimized its capital improvement plan for the Turkey Creek Basin and identified millions of dollars in cost savings.
Turkey Creek Basin, a suburban area where the collection system was under-capacity, suffered from sewer overflows, surcharging and basement backups under the 10-year design storm. The wastewater treatment plant was undersized for the design storm which has a peak flow of 61 million gallons per day.
Johnson County Wastewater
Collection System Master Plan Optimization
- Evaluate wide range of improvement options to meet service levels
- Balance conveyance and storage improvements against I/I reduction opportunities for best mix
- Utilize existing model to quickly formulate Optimizer and develop least-cost solutions
“Optimatics helped us complete a comprehensive evaluation of options for the client facing costly regulatory-driven solutions to sewer overflow problems to identify what our client feels is the most cost-effective solution. The solution was millions of dollars less than what was previously identified through traditional trial and error alternative evaluations completed as a part of prior master planning projects.”
CH2M HILL Project Lead
Optimizer™ was used to identify capital improvements to remedy the current challenges. Rather than a traditional simulation approach, JCW chose to utilize optimization to develop a least-cost capital improvement plan. The resulting design needed to convey the 10-year, 24-hour design storm at proper velocities with no overflows and minimum surcharge. A multitude of improvement options were considered including relief sewers, storage, pump stations, force mains, wet weather treatment, and infiltration/inflow (I/I) reduction costs/benefits.
The optimized solution included new gravity sewer, expansion of a pump station, a new enhanced clarifier, and targeted percentages of I/I reduction for three of the 11 sub-basins. The solution was estimated to save nearly 20% of the cost of a traditional solution developed by simulation alone ($46.5M compared to $51M). Motivated by the results, JCW intends to use Optimatics’ optimization for its future basin planning efforts.
INNOVATION IN I/I REDUCTION.
Reaching optimal cost-effectiveness took a novel approach:
- Estimating costs associated with various levels of I/I removal for each flow metered basin.
- Importing cost curves for each sub-basin’s I/I removal and cost rates for other improvement options into OptimizerTM WCS.
- Running complete hydraulic model simulations in a single optimization run evaluating thousands of configurations while calculating cost estimates and assessing hydraulic performance for thousands of options.
- Identifying the optimum solution to meet service level targets at the least cost.