Presenter/Contact
Presenter
Melissa Reynolds, Assistant City Engineer
Contact Info
(830) 221-4020 - mreynolds@nbtexas.org
Subject Header
SUBJECT:
Title
Presentation and discussion regarding proposed City of New Braunfels drainage policy changes.
Body
BACKGROUND / RATIONALE:
City staff is proposing amendments to the Drainage and Erosion Control Design Manual and the Code of Ordinances, Chapter 58 - Floods. The proposed amendments were recommendations from the Drainage Area Master Plan (DAMP) development and the Community Rating System (CRS) Improvement Report.
The DAMP is currently in Phase 1 which includes updates to regulations to align with State standards and prior to Phase 2 - remapping of floodplains based on new hydrology. This phase also provided recommendations for improvements to the floodplain ordinance to improve CRS rating improvements. This DAMP is intended to function as a comprehensive and holistic watershed program that is sustainable.
The CRS is the National Flood Insurance Program's (NFIP) voluntary incentive program that recognizes and encourages community floodplain management activities that exceed the minimum NFIP requirements. The CRS Improvement Report was intended to investigate the City’s potential to achieve improved CRS rating, creating better benefits for residents.
Drainage and Erosion Control Design Manual
The following amendments are proposed to the Drainage and Erosion Control Design Manual:
Chapter 2 - Drainage Policy and Criteria are proposed and include a new section, Floodplain Development Requirements. This section will include floodplain development requirements, establishing floodplain regulation to the 1% annual chance ultimate development (AC UD) flood, establishing requirements for compensatory excavation in the floodplain to offset lost floodplain volume in the 1% AC UD. Section 2.9 is proposed to be revised to incorporate stream buffers (previously termed erosion hazard setbacks) regulated by contributing drainage areas.
Chapter 3 - Design Rainfall is proposed to be revised ahead of the full policy changes and updates the City’s Design Rainfall to align with the new NOAA Atlas 14, Volume 11 Texas. Note that staff is recommending this change go into effect as soon as possible as presented in another agenda item.
Chapter 4 - Determination of Design Discharge are proposed to update references to design rainfall criteria. Additionally, proposed changes include adding mitigation for the 50-year design storm to the already required 2, 10, 25, and 100-year storms.
Chapter 10 - Detention and Retention Facilities include clarification for maximum water depths and incorporating the 50-year storm frequency to the design criteria for mitigation ponds.
Other updates include updates to Appendices for Definitions of Terms, incorporating new terminology and removing the Stream Bank Erosion Hazard Setback Exhibit.
Code of Ordinances, Chapter 58 - Floods
The following amendments are proposed to the City of New Braunfels Code of Ordinances, Chapter 58, Floods:
Sec. 58-27 - Definitions is proposed to be revised to include new terms and clarification for existing terms.
Sec. 58-28.2 - General Provisions for establishment of the one percent annual chance ultimate development with Atlas 14 as the regulatory floodplain, which is critical to ensure accurate analysis prior to actual map revisions are adopted.
Sec. 58-29 - Administration include designating the floodplain administrator as the City Engineer, updates to reference the current Fee Schedule, and updating the variance procedures to remove the Construction Board of Appeals and insert City Council.
Sec. 58-30 - Provisions for flood hazard reduction is proposed to be amended to include a new section, 58-30.5 Floodplain to include the detailed requirements for development in the floodplain. Additionally, clarifications and reference updates were provided for Sec. 58-30.7 - “No-rise/no-impact certification.”
Review Process
This item will be initially presented to the Watershed Advisory Committee, Planning Commission, and City Council for information and initial feedback. Meetings with the community, including development stakeholders, are planned for November and December 2020. Staff also plans to have the proposed amendments posted on the City website for public comment. The feedback received and proposed text will be considered and discussed at a follow-up Watershed Advisory Committee and Planning Commission meetings in early 2021 for a recommendation to Council.
ADDRESSES A NEED/ISSUE IN A CITY PLAN OR COUNCIL PRIORITY:
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City Plan/Council Priority: Envision New Braunfels Comprehensive Plan |
Action 1.11: Update policies and codes to achieve development patterns that implement the goals of this plan. Action 5.15: Ensure that developers adequately address drainage in their projects and developments. |
FISCAL IMPACT:
N/A
Recommendation
COMMITTEE RECOMMENDATION:
This item will be presented to the Watershed Advisory Committee on October 29, 2020 and Planning Commission on November 4, 2020.
STAFF RECOMMENDATION:
N/A