By BECKY KISER
A private developer's stormwater retention project to be built north of Interstate 70 in Hays will also benefit downstream areas in the city.
MAO Investments LLC (Hays resident Mark Ottley is the managing member) owns the site where the new Hilton Garden Inn and Convention Center is located at 221 W. 43rd, and more property to the west.
The property has a main drainage way, or stream, running through it that goes under I-70 and channels water through the Lincoln Draw area of Hays, which is prone to flooding.
Two retention basins will be constructed in the drainage area.
The smaller basin on the south end will be utilized primarily by the Hilton Garden Inn.
The larger basin will be used for the remaining undeveloped property within the Ottley Addition, with still more capacity - 170,000 cubic feet - that will provide more protection downstream in the Lincoln Draw watershed, Jesse Rohr, Public Works director told city commissioners Thursday night.
The engineering design is already completed by Driggs Design Group, Hays.
There is also a water quality component to the project.
"The bottom of the drainage area is designed with a certain soil mixture and plants that allow water to be filtered before it goes downstream," Rohr said, "which is very important when we're talking about our MS4 permit from KDHE (Kansas Department of Health and Environment). It's a requirement to provide such things and we consider it a best management practice."
Ottley will construct and maintain the project.
The city requires stormwater retention mitigation in new developments.
As Ottley's remaining property is developed, Rohr noted there will not have to be onsite stormwater management on each site as it comes forward in the future.
"So they won't have to utilize space within their lot as the stormwater retention requirement will already be built into the development," Rohr said.
The city will pay Ottley $130,000 from its Stormwater Reserve Fund towards construction of the project.
In 2016, with the development of the Tebo Village property on the east side of 43rd and Vine, a $222,324 fee was paid by the developer to the city in lieu of on-site stormwater retention improvements.
"There were some challenges on that site. That watershed is in the Chetolah Draw Watershed on the east side of Vine, which currently is not prone to flooding.
"We knew we could get more benefit in the future in a project and opportunity if we could spend that money in the Lincoln Draw Watershed on the west side of Vine, which does have some flooding issues downstream," Rohr said.
The Tebo project payment was set aside and "we've basically been waiting for an opportunity to utilize some of these funds for a project such as this to provide an added benefit downstream to Lincoln Draw ."
Ron Mellick asked about safety and the depth of the retention area.
Rohr said the maximum depth is about 6 feet. The sides will be sloped and can accommodate a mower.
"It's not designed to hold water long term. Ideally, within 72 hours after a rain, the stormwater is gone.
"With any of our water retention, if it stands longer than 72 hours, it means it's not functioning. It's not doing its job."
Mason Ruder wondered how undeveloped property south of 41st Street will be affected by the new retention area.
"It might reduce the rate of the volume of water coming down. ... Hopefully, it only has the effect of making it better."
As new construction occurs on 41st Street with impervious surfaces, Rohr said additional stormwater management would have to be done.
Ottley's property between 43rd and 45 streets was originally identified by the U.S. Army Corps of Engineers as a potential site for retention to help mitigate downstream flooding.
Ruder chaired the meeting in the absence of both Mayor Shaun Musil and Vice-Mayor Sandy Jacobs.
With only one agenda item for discussion and a vote, the meeting lasted just 12 minutes.