Collection System Modelling Utilizing Flow and Rainfall Data (Part 1)

This article summarizes the fifth installment in Civica’s Flow Monitoring Webinar Series and will discuss flow monitoring in collection systems. The focus of this post will be on modelling, with particular emphasis on collection system modelling. An overview of the fifth webinar will be provided in two parts.

Ontario’s Infrastructure Growth and Changing Climate

Ontario, as well as many other parts of Canada, is experiencing rapid growth as more people move to the province. Specifically, Ontario welcomed approximately 194,982 immigrants in the last year. It is projected that by 2046, the population of Ontario will grow by 5.2 million.

This growth puts a lot of pressure on municipalities to upgrade existing systems and infrastructure to accommodate such growth.

Municipalities also need to plan or design for the potential of larger storms. According to Environment Canada, statistics show that large high-intensity storms are occurring more frequently, and the volume of rainfall is increasing as well.

Why Are Hydraulic & Hydrologic (H&H) Models Used?

Hydraulic & Hydrologic (H&H) models are usually built for planning purposes and to provide guidance concerning collection system performance for existing and future conditions. They are used to identify capacity constraints and assess Sanitary Pumping Station (SPS), Wastewater Treatment Plant (WWTP), Combined Sewer Overflow (CSO), etc.

In addition, H&H models are used to evaluate alternative solutions. Collection system performance can be evaluated based on theoretical flows (design criteria) or can be calibrated using flow monitoring data. A calibrated model can also be used to predict flooding under extreme weather events.

Why Assess Water Capacity?

Municipalities may have collection system capacity and not know it. With innovation and new technology, such as water usage meters, low-flow toilets, and high-efficiency water use fixtures, there have been improvements (i.e. decreases) in how much water is used per capita.

There are also areas experiencing population reductions, specifically neighborhoods that have a lot of large older homes that used to house families of four or five, but now only house one or two people. These changes in population have actually relieved some capacity in wastewater systems. In addition, there may be less wet weather flow than expected which is impacting these systems. 

Sewage Capacity Issues

sewage capacity analysis

However, sewage capacity issues are a growing concern for many municipalities, and most are faced with capacity limitations, not spare capacity. The cause of these issues can often be attributed to higher than expected wet-weather flows in these systems. As a result, there is an increase in combined sewer overflow (CSO) and sanitary sewer overflow (SSO) volumes, as well as non-compliance with regulatory guidelines and overwhelmed sanitary pumping stations and wastewater treatment plants.

These overflows pose a downstream flood risk and can lead to delayed development approvals. To address the issue, municipalities are faced with the high costs of performing system upgrades and the lengthy process of completing those upgrades.

Assessing System Capacity

There are a number of different ways to assess capacity that vary in complexity and cost. However, the higher the level of complexity, the more accurate and reliable the model is in reflecting what is happening in the real world or in a particular collection system.

The common assessment models, from least complex to most complex and accurate are:

  • Static Analysis (Spreadsheet)
  • Simple Static Model
  • Non-Calibrated Dynamic Model
  • Calibrated Dynamic Model

Contact Civica Infrastructure to Get Free Consultation

Civica is a leader in municipal wastewater management solutions and water flow monitoring systems. Stay tuned for part two of the webinar recap, which will take a deeper look into collection system modelling utilizing flow and rainfall data. For more information, please contact Civica today.

Learn more at: 

Collection System Modelling Utilizing Flow and Rainfall Monitoring Data (Part 2)

CLI-ECA Sanitary Regulations

Intro to Collection System Flow and Rainfall Monitoring

City of Toronto’s Sewer Infrastructure and Sewer Capacity Assessment Guidelines

5 Key Takeaways from the CLI-ECA Stormwater Regulations

Challenges in New Subdivision Flow Monitoring

1 Comment

  1. […] the previous post, an overview of Civica’s fifth webinar was provided. Part 1 explained how Ontario’s infrastructure growth and climate changes are […]