DATE: January 2, 2019
TO: Board of Mayor and Aldermen
FROM: Eric Stuckey, City Administrator
Paul Holzen, Director of Engineering
Jonathan Marston, Assistant Director of Engineering
Jeff Willoughby, Stormwater Coordinator
SUBJECT:
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Consideration of Resolution 2019-01, "A Resolution Directing Staff to Proceed with the Flood Insurance Rate Mapping Associated with Ralston Branch". (Referred to 2/12/19 WS from 1/24/19 CIC 4-0; 2/12/19 WS, 05/19/19 WS)
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Purpose
The purpose of this memo is to provide information to the Franklin Board of Mayor and Aldermen (BOMA) concerning the Ralston Branch Feasibility Study and obtain direction from the Board on how to proceed with the project.
Background
Ralston Creek originates between Huffines Ridge Drive and I-65 near Centennial High School and flows in a southwesterly direction before entering into the Liberty Hills Subdivision Retention Pond. It also receives flow from an eastern channel along Liberty Pike which is listed as the headwater area for Ralston Creek. After leaving the retention pond, the stream flows through the Royal Oaks Subdivision, were staff has received several complaints from residents regarding flooding due to stormwater from Ralston Creek overtopping the stream banks. In addition, this section of stream has experienced some bank failures, which the City has attempted to temporarily address until a permanent solution could be determined and installed.
On November 19, 2015, the Board of Mayor and Aldermen approved a professional services agreement with CEC to work with Staff to prepare a feasibility study to determine potential ways to address flooding in the Royal Oaks Subdivision along Ralston Branch and to mitigate the eroding stream channel. As part of the scope of services, CEC evaluate two flood risk management options to include modifications to the existing retention pond and the installation of a dry dam in lieu of the existing retention pond. Unfortunately,...
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