Achieve More At Less Cost: Local Governments Can Rate Drainage System Capacity Without Need for Expensive Modelling of Every Pipe



Note to Reader:

Federal funding support provided through Natural Resources Canada’s Regional Adaptation Collaborative Program made it possible to develop the Drainage Infrastructure Screening Tool as an add-on to the Water Balance Model (WBM) decision support tool.

The Screening Tool is actually stand-alone from the WBM because it addresses a different evaluation need on the part of local governments. The WBM is used for green infrastructure evaluation whereas the Screening Tool is applied to drainage conveyance systems.

To learn more, click on British Columbia Partnership announces that Drainage Infrastructure Screening Tool is now LIVE!

The original version of the article below was published in the Spring 2012 issue of the Asset Management BC Newsletter. To download the newsletter, click on the following link and scroll down to page 2 to read Your Assets? – Drainage Infrastructure Screening Tool Saves Money! 

Drainage Infrastructure Screening Tool Saves Money!

“A typical situation faced by local governments is this: an existing storm sewer system; some problem areas; limited funding available for system upgrades; and the need to provide flood protection while being fiscally responsible,” states Kim Stephens, Executive Director, Partnership for Water Sustainability in British Columbia. “Many systems operate without serious problems for many years. Furthermore, the vast majority of the time, the system capacity is only partially utilized for conveyance.”

“Yet many engineering studies recommend plans for pipe replacement and upsizing that would cost tens of millions of dollars, money that local governments do not have; while providing no offsetting stream health benefits. Reliance on complex computer models may be having an unintended consequence. Pipe-by-pipe computer simulation of storm sewer capacities is very precise, yet may not accurately reflect reality, thereby resulting in unaffordable infrastructure plans. This is paralyzing municipal decision-making.”

“Why is this happening? Is an apt analogy that modellers are missing the forest for the trees? When unimplementable plans go on a shelf to gather dust, what has been accomplished? Is it time to hit the re-set button vis-à-vis the way we evaluate drainage infrastructure?”

Focus on Solutions

“To shine the spotlight on solutions, the Water Balance Model Partnership has developed a web-based Drainage Infrastructure Screening Tool. City of Surrey and District of North Vancouver case study experience has proven out a screening methodology that saves time, effort and money,” continues Ted van der Gulik, Partnership Chair.

“Now, local governments can focus on what is most important AND achieve more at less cost. They can quickly and inexpensively assess drainage system performance to pinpoint any problem areas. This will help them establish capital budget priorities for detailed analysis during the design process.”

Framework for Screening and Decision-Making

“The guiding principle in looking at drainage infrastructure differently is to provide a uniform Level-of-Service for both drainage and flood prevention, one that is based on a uniform area discharge rate,” explains Jim Dumont, Engineering Applications Authority for the Water Balance Model Partnership. “This would provide an equal level of service or access to the drainage system for all properties within the watershed. Four questions provide a framework for screening and decision-making:

  1. What is the existing level of drainage service within the community?
  2. What will be the effect of climate change?
  3. What will be the effect of redevelopment?
  4. What will be the effect of climate change on redevelopment?”

“The Level-of-Service methodology is embedded in the Drainage Infrastructure Screening Tool. This provides the means to quickly and efficiently identify weak links in a drainage system; and then budget affordable solutions.”

“Actually, the key finding is that a ’90-10 Rule’ applies to most drainage systems. By this, we mean that 90% of the system typically requires no further consideration because the conveyance capacity is adequate under all potential operating conditions. For the remaining 10%, it is a matter of investigating the ‘weak links’ identified by the screening tool to determine whether and what remedial action imay be  necessary,” concludes Jim Dumont.

To Learn More:

To access the tool on the Water Balance Model website and read about the Level-of-Service Methodology, click on British Columbia Partnership announces that Drainage Infrastructure Screening Tool is now LIVE!

In November 2012, the Capital Regional District hosted a Water Balance Model Workshop at its headquarters in Victoria. The workshop featured the case study experience of the District of North Vancouver in developing the Hastings Creek Watershed Blueprint. For a local government perspective on the value of the tool, click on Drainage Infrastructure Screening Tool. The image below is extracted from the storyline.