Wastewater plant operations make important operational decisions based on the influent flow rate to the plant, and despite the ample availability of sensors, there is no accurate industry standard for predicting influent flow rate to the plant.
Knowing the performance of a collection system is difficult because there are few industry-recognized benchmarks on what “performance” is and how it should be determined. Performance of sewer collection systems are often simply educated guesses. Quantifying the areas of highest inflow and infiltration can be difficult due to large networks of pipes, the expense of water monitoring, and varying weather conditions impacting soil saturation.
Municipal sanitary sewer collection and conveyance systems are an extensive, valuable, and complex part of the nation’s infrastructure. Collection systems consist of pipelines, conduits, pumping stations, force mains, and any other facility collecting wastewater and conveying it to facilities that provide treatment prior to discharge to the environment
Plant operators are responsible for ensuring there is enough treated water available for pumping into the distribution or discharge system as well as enough water to maintain ongoing operations. Many operators overlook production water in addition to effluent pumping rates when determining influent rate, this factor ensures treatment is consistent.
Influent flow rates are usually estimated by the operators based on experience and local weather forecasts. These back-of-the-napkin calculations are necessary to engage in master planning for the future of the facility. Determination of the future capacity should be based on needs and sizing, as well as the plant’s ability to meet regulations in the future, and expected timing to update or build new facilities, are all impacted by the irregular and unpredictable amount of influent entering a system.
EPA estimates that the more than 19,000 collection systems across the country would have a replacement cost of $1-2 trillion dollars. The collection system of a single large municipality can represent an investment worth billions of dollars. Usually, the asset value of the collection system is not fully recognized and the collection system operation and maintenance programs are given low priority compared with wastewater treatment needs and other municipal responsibilities.
Typically, small amounts of infiltration and inflow are anticipated and tolerated. Yet, unpredictable weather can increase this load and cause overflows. Management of these events are costly in terms of unplanned labor expenditures, repair of damaged equipment and health and environmental impacts sometimes incurring monetary fines and coverage on the evening news.
As one of the most serious and environmentally threatening problems, sanitary sewer overflows are a frequent cause of water quality violations and are a threat to public health and the environment. Beach closings, flooded basements and overloaded treatment plants are some symptoms of collection systems with inadequate capacity and improper management, operation, and maintenance. The poor performance of many sanitary sewer systems and resulting potential health and environmental risks highlight the need to optimize operation and maintenance of these systems.
Wastewater collection systems suffer from inadequate investment in maintenance and repair often due in large part to the “out-of-sight, out-of-mind” nature of the wastewater collection system. The lack of proper maintenance has resulted in deteriorated sewers with subsequent basement backups, overflows, cave-ins, hydraulic overloads at treatment plants, and other safety, health, and environmental problems.
Managing these complex water systems relies on heavy physical infrastructure and reactive governing attitudes. This is changing with the development of cyber-physical systems, active performance monitoring, big data analysis and machine learning with advanced control systems through the Internet of Things (IoT). These “smarter” systems; in which technology, components, and devices talk to each other and feed information to each other in a more sophisticated way bring about a more optimized, efficient process.
Data provided by weather radar are important in weather forecasting. Rainfall data are typically introduced to provide stormwater information at different locations in the vicinity of the wastewater treatment plant. Several consecutive days of rainfall appears to correlate with increased WWTP flows, indicating a trend that is historically related to interflow.
Goals of prediction to prevent overflows:
- Reduce ratepayer costs by implementing all cost-effective I&I reduction projects
- Minimize liability from water pollution and public health risks by eliminating storm-related SSOs
- Proactive reduce overall I&I to avoid capital costs of capacity expansion in anticipation of future population growth
- Eliminate enough I&I to offset the environmental and regulatory impact of sewer system expansion and increased water demand
Though sensors helped to combat the overflows in South Bend, Indiana for a while, they could only read out that they were being overwhelmed in a recent storm. Yet, if the data from those sensors flowed into a system powered by Artificial Intelligence, operators could have a forecast to predict that storm and may have be able to proactively divert in preparation.
Predictive influent flow rate information is helpful to determine the the most cost-efficient schedule of operating wastewater pumps. Pluto AI has developed a state-of-the-art prediction system which delivers a high accuracy influent flow forecast based on weather forecasts, recent influent flow trends, and the hydraulics of the plant and sewer system to predict influent flow into a wastewater plant.
To assess extraneous water entering your system at least a year of influent flow data to the treatment facility should be examined. Pluto recommends two. Contact us to learn more about integrating predictive forecasting for overflow prevention into your system.
Sources:
https://www.southbendtribune.com/news/local/south-bend-s-smart-sewers-overwhelmed-by-floodwaters/article_cb75b63c-aaa9-5b39-9c9c-df4fcd2b62b3.html
https://www.mass.gov/eea/docs/dep/water/laws/i-thru-z/omrguide.pdf
https://www.globalw.com/support/inflow.html
https://www.ce.utexas.edu/prof/maidment/giswr2012/TermPaper/Boersma.pdf
https://www.mountainview.gov/civicax/filebank/blobdload.aspx?blobid=6979
