User’s Question:

The manager of development engineering services and deputy approving officer for a Vancouver Island municipality posed these two questions to Jim Dumont:

  • Does the WBM require accurate detailed information to be entered to achieve meaningful results, information that the City does not have at this time?
  • Is there an extensive track record of the effectiveness of the WBM?

The context for these questions was an exchange of perspectives that revolved around whether and when it is appropriate for a municipality to specifically require use of the WBM.

Jim’s Response:

“Typical information needed as part of any development design process includes site specific data regarding area, slope, runoff coefficients or imperviousness, and a soil description.”

“The WBM uses the information gathered as part of a normal design process. It does not require the user to have more site information than required by any other system of design.”

“The WBM provides a substantial amount of information in the form of climate data and municipal zoning where individual municipalities have provided the zoning information. In this manner the WBM actually provides information not available in any commercial software package.”

The Calculation Engine:

“The QUALHYMO calculation engine within the WBM has been used and has been enhanced since its first application in the early 1980’s. It certainly has an extensive track record of successful use spanning some thirty (30) years across Canada and in other parts of the world.”

“We recognize that other analysis tools are available to municipalities and that they can be used in the design of drainage and rainwater management systems for developments and municipal works. However, we believe that the WBM has significant advantages over other available tools and is simple to use.”