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How can we improve combined sewer overflow reporting? We need a smarter approach

May 15, 2018

By Martha Fernandes

Tailored analytics platform technology can deliver a better informed, more proactive CSO monitoring and reporting process

Reporting accurate and meaningful combined sewer overflow (CSO) data has long been a challenge. That’s especially true in the Northeast United States, where unpredictable weather patterns and an increasing frequency of severe weather events create the need for extensive long-term analysis of metering data against predictive models. Variables like the amount of snow on the ground during a rainstorm, temperature fluctuations, or local groundwater levels all impact the ability for consistent measurement and confident reporting.

However, a growing need for a real-time approach to CSO reporting—in some cases requiring municipalities to report a CSO spill within hours—is driving our market to take a more holistic, consistent approach to monitoring and modelling. Increasingly, our clients are recognizing the fact that a full picture can’t be achieved without taking a systematic approach to the analysis of CSO flows that is supported by comprehensive historic data.

The U.S. Environmental Protection Agency’s CSO Control Policy has urged utilities to develop a thorough understanding of the wet weather hydraulic responses of their combined sewer systems. To support continuous system improvement, the EPA directed permittees to follow nine minimum controls, with the ninth control requiring that permittees: “Monitor to effectively characterize CSO impacts and the efficacy of CSO controls.”

To adapt to this challenge, we’re increasingly working with clients across New England to advise on strategies for greater accuracy in monitoring and reporting. We’re also preparing them for a more real-time reporting approach.

From CSO projects in South Boston to CSO abatement in Providence, and long-term control plans in between, we’ve learned that if there’s one consistency in this work, it’s that all clients require a tailored solution.

A growing need for a real-time approach to CSO reporting—in some cases requiring municipalities to report a CSO spill within hours—is driving our market to take a more holistic, consistent approach to monitoring and modelling.

A multi-pronged approach

New advances in metering technology have allowed municipalities to gain a more accurate picture over levels and flows, but that metering information is only as good as the quality of data that’s being recorded. We’ve found that, to gain an accurate picture, there’s a great deal of follow-up research and data validation needed. There’s always the chance of a meter malfunction or an uncertain meter placement (such as along an outfall experiencing high river levels) that can skew results.

Metering on its own isn’t especially informative. The full picture truly comes into view when metering data is paired with modelled simulations that have been calibrated and validated over a long period of time during a range of storms.

As you can imagine, this validation and calibration takes time and resources. Our team works with many municipalities for annual reporting that not only takes into consideration metering and monitoring data but also the impacts of external factors. By taking a parallel review of influences like tidal elevations, river levels, and National Oceanic and Atmospheric Administration (NOAA) data, we’re able to paint a more in-depth picture that takes all variables into account.

With the need in many municipalities for a greater frequency in CSO spill report analysis (in some cases requiring CSO spill data to be validated in a monthly report as opposed to annually), how can this extensive analysis and validation be streamlined?

A sample of the OpsGenie web-based CSO analytics and reporting platform.

The future of CSO reporting

As with many aspects of our lives, smart technology has the potential to bring a more systematized and adaptive approach to analysis and CSO reporting. Cyclic in nature, the approach focuses on continual learning with frequent interventions to check confidence and, where necessary, apply course corrections.

Through our internal research and development initiative, Stantec has embraced new and emerging technologies to pioneer a tailored platform-based solution. Known as Ops Genie, this tool provides real-time analysis of combined sewer overflow spill compliance in an integrated platform that can pair with a municipality’s current asset management tools to compile all data relevant to operations and maintenance.

This web-based platform allows for the analysis of rainfall in comparison to additional influences like flow metering information, rain gauge data, and regional CSO network-related data. As we look to the future, there’s also the potential for machine learning to develop more predictive analytics that consider the connections between a CSO spill and impacts to asset performance in relation to data like rainfall, river level, and pump station operation.

The platform is also capable of providing an early warning, through predictive analytics, that a spill or flooding could occur based on historical data in the platform.

The implementation of an integrated, real-time approach not only helps to streamline the reporting process. These in-depth, and eventually predictive, analytics can serve to help communities with their future capital projects, with compliance to shifting monitoring and reporting regulations, and overall asset management.

  • Martha Fernandes

    A water resources engineer, Martha specializes in sewer separation, watershed management, and combined sewer overflow systems.

    Contact Martha
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