PLDRC forwards stormwater ordinance, including 6-inch safety factor, to County Council

The Volusia County Planning and Land Development Regulation Commission voted unanimously to forward Ordinance 2025-06, Division 8 stormwater management amendments, to the County Council for consideration after presentations from county staff and NRAC (Natural Resources Advisory Committee).

Commissioners and staff said the changes are intended to reduce future flooding and make pond designs more resilient. Samantha West, Volusia County sustainability and resilience manager, told the commission: "Both the LID and these proposed stormwater management ordinance changes will be going to the February 11th County Council special meeting." She described the ordinance as a product of NRAC review earlier this year.

NRAC and county staff recommended several technical changes to design practice. County engineer Tad Kays described the central technical change: adding a 6-inch safety factor to the seasonal high groundwater elevation used as the design normal for ponds. "This creates more volume overall," Kays said, explaining that the safety factor raises pond bottoms and therefore increases available storage for storms. He said the county uses a 25-year, 24-hour storm for open basins and a 100-year, 24-hour storm for closed basins when comparing pre- and post-development runoff.

Other provisions recommended by NRAC and included in the ordinance that PLDRC forwarded to Council: a required minimum number of soil borings for pond sites (NRAC recommended two borings per acre as a baseline), a conservative approach to curve numbers when soils maps show mixed hydrologic groups (requiring design to assume the more runoff-prone condition), staff involvement to set conservative downstream "tailwater" elevations before modeling, and siting and structural requirements for ponds located adjacent to lower neighboring property (for example, clay cores or concrete emergency weirs to prevent catastrophic bank failures).

Staff emphasized that the ordinance applies to new development and is not retroactive; existing built projects will not automatically be altered by the change. Kays noted that if an applicant wants staff to accept a different tailwater assumption or seasonal-high elevation, county staff should be engaged early in design to avoid downstream disagreements during review.

Public commenters and local land-use attorneys largely supported the direction but urged clarity and coordination with low-impact development (LID) standards that are going to County Council in the same meeting. Mike Woods of Cobb Cole said the proposed changes and the LID rules "work out really well" together and cautioned that regulations adopted now should keep the policy context and purpose visible so future applicants and reviewers do not treat numbers rigidly.

The PLDRC motion to forward Ordinance 2025-06 to County Council passed unanimously; the commission recorded the recommendation of approval and directed staff to present the ordinance at the County Council special meeting on Feb. 11.

The ordinance, as presented to PLDRC, would add the following notable technical requirements: a 6-inch safety factor on the measured seasonal high groundwater elevation for pond design; a default of two borings per acre for pond subsoils investigations; use of the more runoff-prone hydrologic curve number where soils mapping shows mixed groups (for example A/D); and specific downstream protections (clay cores, concrete weirs or other staff-approved measures) where pond elevations are higher than adjacent properties.

County staff and NRAC members said the goal is to reduce the chance of future failures like recent local pond overtopping events and to make stormwater controls more robust as regional rainfall patterns change.

The County Council will consider Ordinance 2025-06 at a specially noticed meeting on Feb. 11, 2025, where staff and members of the public may provide additional comment.