For years, the model for most local drainage systems-especially in large development sites not directly downtown-has been underground pipes running into a large detention pond.
The ponds have dotted the landscape, becoming a perk for office dwellers and homeowners wanting a “lake” view, but raising the concern of many safety officials over the increased risk of drownings.
But as new federal rules come into effect requiring not just flood prevention but also filtration of contaminants, more developers may be moving toward alternative drainage systems. And as land prices soar, builders in even non-urban settings are using underground or natural drainage arrangements.
Underground systems, long a good fit for small, downtown parcels, are moving out a bit more into the suburbs.
Indianapolis-based Duke Realty Corp., for example, used detention ponds during the development of most of its huge Parkwood Crossing office complex at North Meridian and 96th streets.
But as land near the complex became scarce, the company turned to an underground drainage system for office buildings Parkwood 8 and Parkwood 9.
Duke will also use an underground system at its new addition to the site-Parkwood West, an almost-560,000-squarefoot office and restaurant complex.
“With the rising cost of real estate in desirable locations, like Parkwood West, underground detention allows you to have more usable land,” said Blaine Paul, a development services manager at Duke.
Storm water rules long in place require developers to offset any impact new buildings will have on potential flooding-meaning if a property contains a farm before a new building is developed, the new building must include a system that slows water runoff as much as the farm
and all its permeable surface. The usual answer is to use curb cuts and sloping of land and roadways that force the water to run into drainage pipes and into ponds that detain the water and release it slowly into natural streams. In central Indiana, most man-made ponds are detention ponds that include a drainage system, as compared with retention ponds, which are built on sandy soil and drain naturally.
For entirely underground systems, the water flows from parking lots and other surfaces into grates and goes into underground pipes. But the pipes feed into underground storage pools similar to septic tanks. Those pools detain the water and release it slowly, but take up no ground-level space on the property. These systems are usually placed completely under parking lots.
“In that scenario, we basically utilize that space twice,” Paul said.
That was also the reasoning behind an underground system installed during the recent reconstruction of Riverside Elementary, about 10 blocks north of the IUPUI campus.
Terry Greene, executive vice president of construction for Indianapolis-based Geupel DeMars Hagerman, helped oversee the project.
“[Underground systems] are becoming more and more common because land is becoming more valuable,” Greene said.
But they’re still fairly unusual for Indianapolis, he said. Of the roughly 20 projects Geupel DeMars Hagerman has in the pipeline, only three will have underground systems, Greene said.
There are also environmental benefits to an underground system.
For traditional detention ponds, the sun often beats down on the water, heating it to high levels before it’s released into a stream, which can throw off the stream’s natural balance. For underground systems, heat isn’t a factor.
Fertilizers put on grassy areas next to traditional detention ponds can run off quickly into waterways, but have farther to travel with more chances of getting filtered out in an underground system.
And an even more progressive form of drainage control is making inroads into central Indiana-low-impact development, which uses plants to filter, soak up and control storm water runoff.
“Underground and low-impact development isn’t new,” said Williams Creek Consulting Inc. co-founder Neil B. Myers. “It’s just new to the way of thinking here locally.”
And Myers’ Indianapolis-based engineering company is a case study because its phenomenal growth mirrors the blossoming local interest. It has grown from handling one low-impact development project in 2004 to 50 this year. It added an office in Columbus, Ohio, and is scouting for a third Midwestern location.
When tackling runoff management, a traditional system can be expensive because it usually requires the addition of fill dirt to raise buildings and parkinglot pads to ensure the water will drain into a piping system.
After studying a site, Williams Creek offers alternatives based on natural sloping of the land and by depressing certain areas to attract the water. For example, instead of putting in pipes and raising a parking lot, the company might recommend sloping a lot and draining it toward a central strip of landscaping that will soak up most of the extra water and use it to irrigate plants.
“You have to landscape a site, anyway, and with low-impact development, you don’t have to irrigate these areas,” he said.
Myers said the uniqueness of its projects sometimes bring developers to the company’s doorstep, but “it’s the improved profitability we can bring to the project that keeps their interest.”
Williams Creek was brought in as a consultant on the second phase of Duke’s massive Boone County industrial development called AllPoints at Anson. Its redesign of water control on the site saved six feet of fill dirt and kept the company from using any underground pipes.
Myers said two similar projects are under development in Hamilton County, but declined to give specifics because they haven’t been announced.
At the residential portion of one mixed-use project, the site’s original storm-water design called for moving 50,000 yards of dirt and installing 12 swirl chambers, which help reduce particles in water. By redesigning the site, Williams Creek eliminated the need to move dirt and for the chambers, saving the developer millions of dollars.
The developer of another retail project planned to buy an additional three-acre parcel for an enormous detention pond. Williams Creek’s redesign gave the developer more parking space without the need for a pond-cutting $2.2 million in costs.
“Developers need to get away from the idea that sustainable means tree hugger,” Myers said. “Sustainable means added density.”