TO: Mayor and Members of City Council
THRU: Adam Lindsay, Assistant City Manager
FROM: Sheila Thomas-Ambat, Public Services Director
Alicia Lanier, Stormwater Project Manager Special Projects
DATE: May 6, 2024
RE:
Title
Watershed Master Plan Program 2nd Tranche Proposed Solutions
end
COUNCIL DISTRICT(S):
Council District(s)
All
b
Relationship To Strategic Plan:
Supports Goal 3. City investment in Today and Tomorrow, through the Strategic Objective 3.1 Enhance city street connectivity, traffic flow, and stormwater systems.
Executive Summary:
Two presentations are provided to cover the 2nd Tranche of proposed solutions. The first will present proposed solutions from Little Rockfish Creek 1 and Bones Creek watershed studies. The second presentation will cover Cross Creek watershed study. From this presentation, staff seeks concurrence from City Council to approve staff to program the proposed solutions from Little Rockfish Creek 1 and Bones watershed studies into the annual CIP prioritization process and pursue grants as applicable.
Background:
The Watershed Master Plan program was initiated in FY 2019 to provide a comprehensive City-wide evaluation of the flooding issues in Priority 1 areas and to develop proposed solutions. Priority 1 areas to be studied were identified by high level modeling of the 15 watersheds in the city, with results vetted by staff and compared to historical flooding complaints.
For each watershed studied to date, a score to identify areas of concern is developed based on impacted lane length, emergency facilities, road-crossing risks, and disconnected structures, and impacted structures. The level of service, defined as the largest storm event that can be safely conveyed by the stormwater system or asset, is identified for existing assets. Where the desired level of service is not met, proposed solutions are developed to mitigate the impacts. How well the proposed solution mitigates the flooding is captured in the efficacy rating.
Proposed Solutions from the first round of watersheds (Little Cross Creek, Little Cross Creek Pilot, Beaver Creek 3, Cape Fear 2, and Rockfish Creek) have been developed and presented to Council as the 1st Tranche. Blounts Creek proposed solutions are considered part of the 1st Tranche as well. The studied areas of these watersheds encompass 12.4 square miles of the city. A total of 204 proposed solutions were developed with an estimated total cost of $525M. These proposed solutions collectively mitigate 49 miles of impacted lane length, 62 road-crossing risks, 867 disconnected structures, and up to 220 impacted structures. Nine prioritized proposed solutions were brought to Council for consensus to move forward with design in December 2021. Council approved staff to program the 1st Tranche proposed solutions into the CIP in December 2021. Blounts Creek Watershed brought the Russell-Person Street Bridge Replacement and Stream Enhancement project to Council to move forward with design and seek grant funding for future construction in June 2022. In addition, two other cap stone projects have been brought to Council for approval to seek grant funding for further evaluation (Rose Lake in the Cross Creek Watershed and Locks Creek in the Cape Fear 2 Watershed.)
Today the 2nd Tranche of proposed solutions from the Little Rockfish Creek 1 and Bones Creek watershed studies is presented. Cross Creek proposed solutions are considered part of the 2nd Tranche as well. However, because the Cross Creek watershed is larger and more complex solutions were identified, a separate presentation on the proposed solutions from the Cross Creek watershed study follows this one.
The 2nd Tranche combined total studied area is 14.1 square miles, with 111 proposed solutions at a total estimated cost of $470M. These proposed solutions collectively mitigate 64 miles of impacted lane length, 353 traverse road crossing risks, 59 disconnected structures, and up to 332 impacted structures.
The 2nd Tranche subset of just the Little Rockfish 1 and Bones watersheds studied 9.74 square miles of the city. A total of 28 proposed solutions were developed with an estimated total cost of $90M. These proposed solutions collectively mitigate 8.8 miles of impacted lane length, 11 traverse road-crossing risks, 32 disconnected structures, and up to 141 impacted structures.
Issues/Analysis:
Proposed solutions are not moving forward to project development at this time. However, approval enables staff to program them into the Stormwater CIP prioritization process. The prioritization of proposed solutions takes into consideration a number of factors before recommending them to Council for project development. Solutions are sorted based off of Concern Area Score (“Worst First”) and efficacy. Staff has then targeted an equitable distribution between watersheds as well as strategic selections, such as a project’s ability to be considered for grant funding or a project’s proximity to other construction related activities (i.e. NCDOT improvements or Resurfacing).
The prioritization of proposed solutions should not be viewed as a static list to be done in sequential order. As study areas are completed, new proposed solutions are developed that adjust priority ranking and flexibility exists in those proposed solutions ranking the highest. All proposed solutions recommended to move forward to project development thus far have been brought before Council for approval. These 12 proposed solutions make up 10 projects that are currently under design or about to begin construction.
Budget Impact:
There is no impact to the General Fund.
Options:
1. Council provides consensus to approve the 28 proposed solutions from the Little Rockfish Creek 1 and Bones Creek watershed studies to enable staff to program them into the annual CIP prioritization process and pursue grants as applicable.
2. Council does not provide consensus to approve the 28 proposed solutions from the Little Rockfish Creek 1 and Bones Creek watershed studies and remands back to staff with additional guidance.
Recommended Action:
Council provides consensus to approve the 28 proposed solutions from the Little Rockfish Creek 1 and Bones Creek watershed studies to enable staff to program them into the annual CIP prioritization process and pursue grants as applicable.
Attachments:
Watershed Master Plan 2nd Tranche Proposed Solutions.pdf