Assistant City Engineer Cody Burnett talks about proposed updates to Starkville's stormwater ordinance. The city is considering strengthening the ordinance. Photo by: Alex Holloway/Dispatch Staff
April 15, 2019 10:33:43 AM
Starkville is looking at strengthening its stormwater ordinance to help prevent future problems with flooding.
Assistant City Engineer Cody Burnett updated aldermen at a work session Friday on a proposed revision to the ordinance, which is included in the city's larger ongoing development code rewrite. The city's development code lays out the city's requirements for zoning and land type designations, as well as the processes and guidelines for building new developments or altering existing ones.
Friday's update was prompted by flooding due to heavy rains earlier in the week.
One change for the ordinance, Burnett said, is that it would require new developments or redevelopments to increase the amount of stormwater that can be retained.
The city's current ordinance requires developments to retain enough water from two- or 10-year rainfall events. Under the proposed change, the requirement would be increased to handle enough rainfall for a 100-year event.
"Year" events are determined by the likelihood of a particular amount of rainfall falling at a location in any given year, according to the U.S. Department of Agriculture. For example, a two-year event has a 50-percent chance of happening in any year, and a 10-year event has a 10-percent chance. A 100-year event has a 1-percent chance of happening at a location in a given year.
Burnett said the increase in the threshold is not a multiplication. For example, a property that has to prepare to retain enough stormwater for a 10-year event in Starkville must be able to handle six inches of rain in a 24-hour period. Preparing for a 100-year event would increase that to 9.4 inches of rain in 24 hours.
"I know that sounds like a lot at first, but it's important to keep in mind that a 100-year event is not 10 times greater than a 10-year event," Burnett said.
"One note is that a lot of engineers are already designing systems for this 100-year event because it's common in other municipalities as a measure of safety," he later added. "We're just hoping to make this a requirement, rather than a suggestion."
Burnett said the city's stormwater ordinance hasn't been updated since 2010. The city has looked to similar municipalities, such as Oxford, Tupelo and Columbus, for guidance on the updated ordinance.
"Since then, there's then been a good bit of technology and literature released, so this is a great time to be updating this code," Burnett said. "I think it's worth saying that all updates and revisions are under review and subject to change. Even though we are approaching a final product, we're still getting feedback from other departments and colleagues."
The proposed updates also include a provision that would automatically trigger downstream drainage studies for developments of certain sizes. Burnett said there have been issues with developments causing flooding in other areas, due to increased runoff. The change would seek to help mitigate that problem.
Any new development larger than two acres would need to conduct a study to determine how best to handle increased runoff and whether to implement stormwater storage adjustments to prevent flooding.
"If they are capable of meeting the stormwater ordinance as is, this is a little more work but it's not more difficult work," he said. "It's pretty intuitive if you know how to do what we already require."
Ward 3 Alderman David Little, who Burnett said asked for the update, said he liked the city taking a stricter approach to dealing with stormwater.
"I'm pleased with us going with the more stringent stormwater ordinance," Little said. "Newer developments shouldn't be encountering these problems, in my opinion."
Little said some neighborhoods, like the second phase of Country Club Estates, have problems due to natural creeks being altered during development. He said he'd like to see the city take a look at addressing those problems, moving forward.
"When that's at capacity, that little channel overflows the culvert and starts running down the street," he said. "We haven't had any homes impacted and probably won't, I would hope, but nevertheless, you can't drive down through that area and Pebble Beach (Road) when it's happening."
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