COLUMBIA — The city’s Grissum Building will get a makeover to study the effectiveness of several strategies for treating stormwater and reducing runoff as part of a nearly $500,000 project coordinated by the city and Boone County.
The building, which houses several Columbia Public Works Department operations, has been selected as a test site for six retrofit projects to reduce runoff and filter contaminants to the Bear Creek watershed. Boone County has received federal grant money to cover part of the project, which is intended to improve water quality in Bear and Hinkson creeks, according to a report to the Columbia City Council from the the Public Works Department.
The EPA has listed Hinkson Creek as an impaired stream since 1998 because its pollution levels exceed agency standards.
In January 2011, the EPA recommended the city and county take steps to reduce storm water runoff to Hinkson Creek by 39.6 percent. Some of those suggestions will be tested at the Grissum Building.
Citing high costs and incomplete data, the Missouri Department of Natural Resources, the city and the county moved forward with their own plan in August to examine other sources of pollution for both creeks and the most effective methods to improve their water quality.
The Grissum project is intended to produce data on the effectiveness of each strategy, city engineer Erin Keys said.
“Even though the property is in the Bear Creek watershed, it will be useful for all watersheds in the area,” Keys said. “It’s important to protect all of our watersheds, not just Hinkson Creek.”
Under the agreement, the city will try several best-management practices to reduce pollution and erosion. These include:
- Two rain gardens in the southwest corner of the Grissum site.
- Porous pavement that would filter rainwater seeping into the ground.
- A series of stormwater conveyance pools to the north that should slow and treat runoff.
- Numerous landscaped bioswales that should trap water pollution in the north and east portions of the site.
Crews from the Public Works, Water and Light and Parks and Recreation departments will do the work, but Keys said it should have no impact on their other operations.
The city will pay a maximum of $253,000 to complete the projects and to communicate findings to area engineers and developers. The county will add more than $210,000 of grant money from the EPA to that sum.
Boone County stormwater coordinator Georganne Bowman said that the conveyance and bioretention systems should be done by the end of the year and that the porous pavement, rain gardens and other projects should be finished in 2013. The agreement charges the county with collecting data on runoff speed and pollution and with monitoring all installations on city property.
The county pledges in the report to publish findings related to runoff management in April 2014. Bowman said that measurement of 20 significant rainfalls for each installation would be ideal and that the timing of a final report depends on weather.
“If we have rainfall like 2008 and 2009, we’re going to be fine,” Bowman said. “If we have rainfall like last year, we may have a problem.”
The idea of a step pool conveyance system came from a study in Maryland. The structure will treat runoff from both the Grissum site and the adjacent Municipal Power Plant, Keys said.
Bowman said data collected at the Grissum site will add to studies conducted on the East Coast about the effectiveness of each installation. The local data should be helpful because soil and weather patterns are different here.
Missouri does not have data about best management practices, Bowman said. “We’re trying to change that.”
As a bonus, the report to the council notes that the projects also will bring the Grissum Building up to standards in the city’s Stormwater Management and Water Quality Manual. Keys said the Grissum site has no water quality treatment facilities. The city manual only requires compliance when property is redeveloped, but the federal money is enabling the upgrades.
At the same time the city retrofits the Grissum site, the county will conduct a similar study in Sunrise Estates east of Columbia. Bowman said the subdivision has had major problems with stormwater because it was built before runoff ordinances were passed. Bowman said the homeowners' association responded enthusiastically to the program.
“They were extremely ecstatic,” Bowman said.
The city and county pledge to conduct a public outreach program to share the findings. The campaign will target developers, engineers and builders as they move forward on construction projects within the watershed of Hinkson and Bear creeks. Keys hopes information about the costs and feasibility of the practices on an already-developed site will encourage others to adopt them.
“Stormwater BMPs are kind of like a mosaic,” Keys said, talking about the best practices. “One little tile by itself doesn’t seem significant, but when you put them together they make quite a picture. The bigger picture is much improved water quality for all of our local creeks and watersheds.”