Dec 06, 2018

Dynamic Sewer Modeling Reduces Capacity Improvement Costs

District saves more than $10 million using system

District saves more than $10 million using system

Central Contra Costa Sanitary District (Central San) in California has always been on the cutting edge of sewer modeling technology. From an early adoption of PCs for tabular hydraulic analysis to using a custom solution for a semi-dynamic 1985 Master Plan model, and then a custom geographic information system-based model in 2010, innovation has always been top of mind for Central San’s sewer modeling team. Following this trend, the district naturally evolved from steady-state modeling to dynamic modeling. To tackle this challenge, Central San, with the help of Woodard & Curran, turned to InfoWorks ICM.

Justin Waples, P.E., has worked for Central San for 10 years and is the district’s hydraulic modeling lead, as well as the recycled water program manager. He was instrumental in moving the district’s modeling capabilities from steady-state to dynamic with InfoWorks ICM. As a result, Central San was able to reduce capacity improvement projects by 30%, saving it upwards of $10 million dollars and easing the cost burden for ratepayers.

The Challenge

With continual growth, and as one of the larger systems in the San Francisco Bay Area (with more than 1,540 miles of underground pipeline ranging in size from 6 to 102 in. in diameter), Central San needed to evolve its sewer model to meet the demands of managing an increasingly complex system. In the steady-state model, peak infiltration and inflow (I&I) rates were only attributed to the age of sewers, which were assumed to deteriorate over time. The district was unable to model sanitary sewer overflow (SSO) volumes, pump stations, surcharge and backwater, and could not estimate sewer flow for specific times of the day. The steady-state platform simply was incapable of handling the advanced computational aspects inherent to modeling Central San’s system.

Central San embarked on acquiring a software solution that satisfied its hydraulic computational needs. Prior to selecting InfoWorks ICM, Central San’s modeling software was not enabled for workgroup collaboration, did not support version control or data audits, and lacked the ability for inference and engineering validation.

central sans system information

The Solution

Waples advocated that the district select a solution that was commercially available, highly compatible and widely respected to help Central San join the ranks of neighboring utilities and reach industry standard.

After evaluating its options, Central San chose InfoWorks ICM. With this new tool, the district could model pump stations, force mains, complex junction structures, overflow volume estimation, and bypass pumping and plugging. And, being commercially available, technical support, bug fixes and new features were made readily available to Central San. 

“It was a critical component to our overall Master Plan, to get accurate flows in the collections system to identify what our true needs were for capacity improvements,” Waples said. “InfoWorks ICM is known to handle complex hydraulic scenarios, and that capability was essential for Central San’s needs.”

With InfoWorks ICM, collaborative work between the team at Central San and its consultant was made significantly easier.

“If we’ve got too much going on, I can request that our consultant do the analysis—it’s quite seamless. They’ll run the analysis and we’ll get the information, just as expected,” Waples said.

The Result

After converting its steady-state sewer model to one that was dynamic, Central San reduced its need for capacity improvement projects by 30%. In terms of savings, Waples estimated “it was at least $10 million dollars—probably a lot more.” For the remaining capacity projects, either pipe size or length of capacity improvement was reduced. Not only did InfoWorks ICM save the district money it would have used on capacity projects, but it also eased the burden of cost placed on ratepayers.

“Just doing that one project for our capital planning paid for itself 10 times over,” Waples said. “It’s definitely a big win for ratepayers, definitely a good savings.”

Central San plans to continue expanding its InfoWorks ICM model to include key areas of interest and complete its system with smaller diameter pipes.



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