Sanitation District No. 1 (SD1) of Northern Kentucky operates wastewater infrastructure for over 200,000 customer accounts. They partner with more than 30 local governments to provide reliable wastewater and stormwater services. Their wastewater asset network is comprised of approximately 1,650 miles of sanitary sewer pipe, 121 pump stations, and multiple treatment plants that treat about 36 million gallons of wastewater each day.
Located at the confluence of the Ohio and Licking rivers, SD1 is committed to operating their wastewater infrastructure with a high level of ecological integrity to protect the receiving waterways. Their wastewater conveyance and plant network successfully prevent over 145,000 pounds of waste from entering the Ohio River each day.
However, when sanitary sewer overflow (SSO) volume became an issue in parts of the Lakeview sewer shed, the professionals at SD1 needed to effectively analyze and plan upgrades to their network to reduce SSOs. Initially, SD1 evaluated a solution put forward through traditional master planning methods. While this plan would have achieved the District’s goals for hydraulic competency and overflow reduction, it came with a high price tag.
SD1 wanted to find a solution that would meet their objectives for overflow reduction at a lower project cost. To achieve this, they worked with engineers at Hazen and Sawyer and used a technology combination of Innovyze’s InfoWorks ICM and Optimizer™ by Optimatics.
With a hydraulic and hydrologic (H&H) model that was up to date and accurate in InfoWorks ICM, the SD1 team ran some manual simulations to determine a baseline for SSO control strategies. With this model connected to cloud-based intelligent scenario evaluation software, Optimizer™, the stakeholders involved could evaluate tens of thousands of options for reducing SSO’s and determine their cost-effectiveness.
“We use InfoWorks ICM for its advanced modeling capabilities and its ability to accurately model complex catchment and H&H interactions,” Sean FitzGerald, PE Vice Present, Conveyance Practice Group Leader at Hazen and Sawyer said. “The ability to connect this with Optimizer™ really gave us an unprecedented level of analysis to solve the challenges in SD1’s wastewater network,” he added.
Initially, they looked at inflow and infiltration (I/I) to see if this would lead to a resolution in the Lakeview basin. The team also used InfoWorks ICM and Optimizer™ to evaluate combinations of conveyance upgrades, storage, pumping, and other control structures. However, through this analysis it became clear that focusing on a combination of storage and conveyance upgrades would provide the best path for reducing SSO’s.
Using InfoWorks ICM and Optimizer™, over 800 individual conduits were grouped into 82 unique decisions. The decision framework only allowed for upsizing of pipes that did not have adequate capacity. The pipe upsizing decisions could choose from 10 possible standard pipe diameters (from 12” to 72”) and used standard unit costs from SD1 based on pipe length and diameter.
Hydraulic performance was determined by heavily penalizing SSO spill frequency and volume at outfalls and manholes, and also considering minimum freeboard exceedance. The minimum freeboard exceedance was further penalized the closer the hydraulic grade line (HGL) came to the ground surface.
Fig. 1 Charted outcomes comparing hydraulic competency and cost at SD1
Using Optimizer™ and InfoWorks ICM models, the team ran approximately twenty-five thousand simulations over the course of the planning period to provide a set of optimized solutions for selection. The analysis made clear the cost and performance of maintaining the status quo, and at which point the hydraulic benefits are optimized according to cost (Fig. 1).
This process of intelligent scenario analysis and simulation through Optimizer™ and InfoWorks ICM provided the same hydraulic competency at half the cost of the original plan – cutting the cost of improvements in half and saving the District tens of millions of dollars.
“We were excited by the results generated by these two solutions,” Adam Chaney, Executive Director at SD 1 said. “To be able to meet our project objectives at an optimum cost gives us confidence that we can keep our waters clean, service reliable, and budgets sound,” he added. With the successful results generated from the Lakeview sewer shed, SD1 has deployed the same solution framework throughout the rest of their wastewater network – with the goal of achieving similar cost savings.