Jan 09, 2008

Better Modeling

From downtown high-rises to ski resorts to major airports, KPFF Consulting Engineers provides structural and civil engineering services for various project types domestically and internationally. One of the company’s 20 offices nationwide is in Portland, Ore., which averages about 44 in. of rainfall per year. The city government has strict regulations regarding storm water treatment and detention and low-impact development.

A New Approach

For storm water modeling, KPFF engineers had used an in-house application. But on larger projects—those of at least 4 or 5 acres—the firm found the software lacked key features to streamline the modeling process. It was on a 300-acre land development project that engineers determined a need for another approach.

“Two or three years into the project, we realized it would have been much easier with more powerful modeling software,” said Faheem Jan, design engineer.

The firm’s storm water team evaluated several storm water modeling software products before selecting StormNET by Boss Intl. The fully dynamic hydrology and hydraulic software analyzes simple and complex storm water systems using a variety of methods and models, including water quality.

KPFF plans to use StormNET for future projects.

Integration & Benefits

In particular, KPFF was attracted to StormNET because its engineers could import AutoCAD drawings directly into the software. It was also cheap and easy to use. Staff members directly import storm water networks from Autodesk Land Desktop and Civil 3D into StormNET, eliminating the need to re-enter manhole and pipe data.

Today, the Portland office uses the software on large-scale land development and site design projects.

StormNET users can quickly develop sophisticated models, primarily with the Santa Barbara Unit Hydrograph hydrology method. If desired, users can also analyze their models using SWMM, TR-20, TR-55, Rational Method and others.

Jan, for instance, can now analyze storm water pipe conveyance and detention pond facilities simultaneously rather than having to run separate analysis models for each. The software clearly shows the storm water network’s bottlenecks and problem areas and allows the user to zoom into any specific part of the network for a closer look (i.e., surcharging along a pipe profile).

Based on municipal requirements, engineers can choose site-specific storm distributions with StormNET’s database of more than 3,500 up-to-date rainfall recording stations across North America. They can also set and easily change conveyance and detention parameters to see the impact of different combinations.

Jan finds that the software’s hydrodynamic routing capabilities allow him to size pipes more effectively than kinematic wave or steady-state methods. If he needs to change pipe sizes, dimensions or any other network elements, the rest of the model automatically adjusts in response to the change, so he no longer must manually adjust other calculations.

Although KPFF’s Portland office has not yet utilized StormNET’s water quality capabilities, they should prove important in meeting the city’s strict storm water treatment requirements. The software accounts for any type of storm water quality factors (i.e., total suspended solids, total maximum daily loads) and can incorporate rain gardens, bioswales and other best management practices in its analysis.

Jan said that StormNET reduces engineering modeling time on projects by about 50 percent. “For example, instead of maybe eight hours, it’s now only four,” he said. “On a large project, cutting half the time means we can get the project completed more quickly and efficiently. Because we can run multiple scenarios easily, it definitely enhances the accuracy and quality of our projects.”

About the author

<i>Casey Hibbard is with Compelling Cases Inc. Hibbard can be reached at 505.473.3145 or by e-mail at [email protected].</i>

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