The Central Contra Costa Sanitary District – called “Central San” by the locals – is one of the larger water systems in the San Francisco Bay region. Located about 30 miles east of San Francisco, the district is responsible for the collection and treatment of wastewater for half a million residents and 3,000+ businesses, cleaning around 13 billion gallons of wastewater each year.
With 1,540 miles of underground pipeline ranging in size from 6 inches in diameter up to a massive 102 inches in diameter, they have a large footprint to maintain.
Central San pride themselves on being early adopters. They originally used PCs for tabular hydraulic analysis and began dabbling in their own custom software solutions as far back as 1985, transitioning to custom GIS-based modeling in 2010.
Since then, they’ve been steady-state modelers, but they outgrew the limitations of their existing software – and grew impatient having to extend their model based on just a single snapshot in time. They were ready to transition to more dynamic hydraulic modeling. To help them make the switch, they recruited the help of consultancy firm Woodard & Curran. The big question was: which software should they choose?
Moving from steady state to dynamic hydraulic modeling
The California State Water Resources Control Board requires every wastewater collection system agency to assess their current and future capacity requirements for collection system facilities. That wasn’t easy using their previous software. They knew they could get a lot more data – and dramatically increase the accuracy of that data – by moving away from a stand-alone static snapshot and towards a dynamic modeling solution.
With that previous software, peak infiltration and inflow (I&I) rates were a particularly problematic area for them. Without being able to accurately model their sewer network pipes with deep granularity, they often had to attribute their lack of reliable I&I information simply to the increasing age of their sewers, which were naturally assumed to deteriorate over time.
Even worse, without dynamic modeling to rely on, they were unable to model Sanitary Sewer Overflow volumes. SSOs are a serious concern around the San Francisco Bay, and the area Central San serves includes some heavy industries that need to be closely regulated. Without the ability to model pump stations, they couldn’t fully understand the details of surcharge, backwater, or even calculate accurate sewer flows at specific, important times of the day. Simply put, their steady-state software was incapable of handling the advanced computational aspects they needed to accurately to model their system.
Choosing the right software platform
Hydraulic Modeling Lead Justin Waples, PE, who also does double duty as their Recycled Water Program Manager, has worked for Central San for 10 years. He helped spearhead the search for the right software solution that would satisfy their hydraulic computational needs.
Waples wasn’t just looking for better hydraulic modeling capabilities. He also wanted features that their existing software couldn’t provide that had long been on their wish list: workgroup collaboration, version control, auditing capabilities, and tools to help engineers infer and validate their work. He also preferred investing in software that was commercially available but open enough that it could be compatible with multiple, popular, industry-wide formats.
After evaluating their many options, Central San chose InfoWorks ICM and got to work importing pipe and structure feature data for their defined trunk system. They verified gate and stop log positions at junction structures, conducted flow monitoring over the wet season to calibrate the model, and kept importing pipe feature data for the main line system until they had a complete, dynamic hydraulic model with accuracy that they and their consultants can rely on.
Now, they can model pump stations, force mains, complex junction structures, estimate overflow volume, as well as bypass pumping and plugging. “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.” says Waples. “InfoWorks ICM is known to handle complex hydraulic scenarios and that capability was essential for Central San’s needs.”
With InfoWorks ICM and its support for popular input and output formats, collaborative work between the team at Central San and their consultants was also made significantly easier. “If we’ve got too much going on, I can request that our consultant do the analysis,” says Waples. “It’s quite seamless. They’ll run the analysis and we’ll get the information just as expected.”
Immediate cost and productivity savings
After converting their main existing steady-state sewer model to one that was dynamic, Central Contra Costa Sanitary District reduced their need for capacity improvement projects by 30%. For the remaining capacity projects, either pipe size and/or length of capacity improvement was reduced.
Not only did InfoWorks ICM save the district money they would have used on capacity projects, it eased the burden of cost placed on ratepayers. Waples estimates savings of “at least $10 million dollars – probably a lot more. It’s definitely a big win for rate-payers, definitely a good savings. Just doing that one project for our capital planning paid for itself ten times over.”