Doing their part: Cisterns show how to keep runoff out of the Cedar River
Cedar Rapids library, U.S. District Courhouse, firestation added systems to renovations
CEDAR RAPIDS — This is the nervous time of year here as spring rains fall and the Cedar River rises.
Nearly six years now since the city’s historic June 2008 flood disaster, three hard-hit flood victims have done more than remember.
All three — the Cedar Rapids Public Library, the U.S. District Courthouse and the city’s Central Fire Station — have incorporated cistern systems at their new homes to catch rain runoff and, in the process, to do their part to show how individual properties can help prevent future flooding.
The cistern systems not only harvest and sequester rainwater, as Bruce Hamous, an architect with OPN Architects Inc. of Cedar Rapids who worked on the library project, put it, but two of the three systems use the captured water to irrigate greenery on their sites.
Hamous, Jim Snedegar, regional chief architect for the U.S. General Services Administration who helped oversee the Cedar Rapids courthouse project, and Greg Buelow, the city’s public safety spokesman, said each of their cisterns are designed to hold rain water from nearly all rains on their sites and either keep it out of the city’s stormwater system or slowly release into the sewer system and then the Cedar River.
Hamous and Buelow said the library system and the fire station system will begin to send water into the storm sewer system if there is more than a one-inch rain in 24 hours. Snedegar said the courthouse cistern system can handle about two inches of rain in 24 hours.
The library’s cistern system is the poster child of systems because its central features are visible and photogenic, and are intended to serve as an educational lesson for years to come about water management, flooding, green building design and sustainability.
“In addition to the obvious benefit of stormwater management, the library trustees saw the cistern system as an opportunity for ‘teachable moments’ on our rooftop,” said Joe Lock, library board vice president and head of the library’s building committee.
The library, he said, has tagged its roof “our LivingLearning Roof,” and he said it comes replete with educational signs to explain how the cistern system and the green roof works.
As OPN’s Hamous described it, the library’s cistern system captures rainwater that drains from the third-story roof above the library auditorium and part of the lobby, and sends it to two 5,000-gallon cisterns on the library’s second-floor roof.
Water from the cisterns then is sent into an irrigation system of below-the-soil plastic pipes to water the 14,000 square feet of plantings, which are now coming to life this spring and which comprise the library’s green roof.
A solar panel on the cisterns helps to provide electricity to the irrigation system controller.
In addition, the library has a system of underground chambers under the library parking lot that holds water that drains from the rest of the library site and releases it slowly to percolate into the soil. More than an inch of rain in a 24-hour period will send some of this water into the city’s stormwater system.
Hamous said public and private buildings across the nation now are incorporating green-design water management practices, and some have cisterns and some have green roofs.
But he said the library’s design is unique because it has cisterns and it uses the cistern water to irrigate an expansive green roof that itself is designed for the public to interact with and not simply look at.
“Obviously the destruction of the library was an unprecedented event in the nation in terms of the number of books and materials lost,” Hamous said, speaking of the 2008 flood. “I think it was the largest public library destroyed by a natural disaster. So we felt that it was incumbent up on us to build as much sustainability and greenness back into this building when we had the golden opportunity to do so.”
GSA’s Snedegar said the new federal courthouse’s underground concrete cistern can hold 8,000 gallons of water runoff before it begins to send water into the city’s stormwater sewers. Water from the cistern is pumped into an irrigation system that waters trees on the courthouse site.
The system also features a “treatment box,” where 90 percent of the dirt, debris, oil and other substances are captured from the water before it is released, he said.
Snedegar said the cistern and irrigation system cost relatively little, especially as it was incorporated into the building as it was being constructed. The savings in water costs to irrigate trees and other savings made the payback period on the cistern system “very short,” he said.
Hamous noted that a similar calculation for a return on investment on the library project has been harder to make. For example, he said the library roof needed additional support to hold two cisterns that can hold 5,000 gallons of water each.
Incorporating green design and building into a project typically can add about 1 to 2 percent to the cost, though he said half of a green building’s sustainable features don’t cost anything to add.
The Central Fire Station has been awarded the top platinum certification from the Leadership in Energy & Environmental Design program, or LEED, and the library is in the process of seeking a similar certification. The federal courthouse project obtained the LEED gold standard, a step below the platinum standard.
Much of the benefit of competing for and securing LEED certification is measured in more “philosophical and community-based” ways as well as cost savings over time, Hamous said.
In addition to sending less water into the city’s stormwater system and the river, the library’s cistern-fed green roof improves the overall quality of the air in downtown, and it lowers the “heat-island effect” that is created by a large expanse of a black, heat-absorbing roof, he said.
“And then there is just the enjoyment of being up on the roof,” Hamous said. “Of being able to read a book or visit with a friend or have a meeting on a nice day in a place where you can look around and enjoy the surroundings.”
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