Preparing your stormwater system for historic rainfall and flooding

City of Golden, CO

It’s a familiar concern for stormwater professionals: Is my system prepared to handle the next storm? What if it’s a 100-year flood? A 1,000-year rainstorm?

These events hit Colorado in September 2013, wreaking havoc across 2,000 square miles of the Front Range of the Rocky Mountains. Torrential rains far exceeding previous records caused widespread flash flooding that damaged or destroyed some 20,000 homes and commercial buildings, 485 miles of roads, and 50 bridges, reported the National Oceanic and Atmospheric Administration.

The 17 affected counties included Jefferson County, home of the City of Golden. While not in one of the hardest hit areas, Golden experienced a year’s worth of precipitation in less than a week. Nonetheless, “The amount of damage we incurred was very minor,” says public works director Dan Hartman, who attributes the damage control at least in part to the effectiveness of the city’s Cartegraph Operations Management System.

CHALLENGE

That level of preparedness was not always in place. According to Hartman, when he took his position in 1988, Golden was “a wait-for-a-break-and-respond organization.” Assets were not quantified and there was no ongoing reinvestment program, he says. This situation made it difficult to maintain stormwater and other systems at the operating level for which they were designed. Setting his sights on developing an investment plan, Hartman began to implement a rudimentary asset management system.

The first step was to update the existing, meticulously hand-drawn maps of city systems. Those maps showed 32 miles of water distribution lines and 38 miles of sewer lines, but no record of the stormwater system. Hartman commissioned aerial surveys, which revealed the systems were nearly double what the hand-drawn maps showed: 79 miles of water lines and 72 miles of sewer lines. Also identified were 66 miles of storm pipes and 11 miles of storm channels. With the maps updated, the public works team started capturing asset data in an early generation computer-based system.

SOLUTION

In 1999 Golden transferred that data into Cartegraph and for the first time was able to integrate GIS with asset and work management.  All of the city’s assets were recorded into what became a robust database, says Hartman. “We used basically every module—water, wastewater, stormwater, streets, trees, signs, etc.” With a clear picture of the dollar value, condition, and life expectancy of every asset, Hartman could more easily make realistic projections for the annual investment to maintain the systems.

The stormwater team now conducts detailed annual inspections of the city’s thousands of storm inlets, manholes, outfalls, detention ponds, pipes, and channels. In addition, drive-by inspections are made following storms to discover any resulting stoppages. These regular inspections keep the system prepared for whatever Mother Nature throws its way.

Golden recently transitioned to Cartegraph’s new platform, the Operations Management System (OMS), which is a web-based application that connects to the ArcGIS platform. This mobile-friendly technology brings mapping, asset management, and work management tools to the field, which streamlines workflow and data entry.

When performing inspections of the stormwater system, workers now use iPads to navigate to the inspection site, go through a detailed checklist, make necessary notes, attach photos, and document that the inspection has been completed. If they discover an asset that’s not up to par, they schedule needed repairs by creating a task on the spot.

When clearing channels, rebuilding detention ponds, fixing inlets, and performing other maintenance, workers log their data in the field, providing a real-time record of the work completed, who performed it, how much time it took, and materials used.

“For stormwater, the key benefit of operations management is that it provides us with an organized approach to inspect, maintain, and repair our system,” says Hartman. “It allows us to document that our system is functioning to the highest level it can.”

RESULTS

The record flooding of 2013 put Golden’s stormwater system to the test. “The system performed well. The inlets were open and the detention ponds were clear so they could do their jobs,” says Hartman. “You can’t start fixing those things when the rain starts.”

As a result, Golden can be confident that the stormwater system can handle at least the maximum level for which the system was designed. “To the extent our system could protect us from damage, it did,” says Hartman. “That is due in part to our regular inspections and the technology that helps us track the condition of the assets in the system.”

Hartman said his team has been pleasantly surprised by other benefits of using Cartegraph:

• When inlets are routinely maintained, repairs on assets such as pipes or catch basins can be conducted more quickly because crews don’t need to spend time cleaning out the inlets before they can reach the problem.
• Comprehensive data helps with liability issues, as in a case where a resident initiated a complaint against the city for flooding damage. “Because of our drainage system management program and documentation of it, their lawyers never bothered to file the suit,” says Hartman.
• Cartegraph serves as an archive of all work completed on the stormwater system. When issues arise or questions come up, it’s easy to find the information needed to solve or better understand the problem.