Presenter/Contact
Presenter
Garry Ford, P.E., City Engineer
Contact Info
(830) 221-4020 - gford@nbtexas.org
Subject Header
SUBJECT:
Title
Discuss and consider approval of proposed amendments to the City of New Braunfels Drainage and Erosion Control Design Manual.
Body
BACKGROUND / RATIONALE:
This item was presented to City Council on August 14, 2017.
In accordance with the Code of Ordinances, the city engineer is hereby authorized and directed to promulgate city standards for the design, construction, installation, location and arrangement of drainage facilities. The city engineer shall submit such standards to the planning commission for recommendation to city council and, thereafter, file such standards with the city secretary at least ten days before they become effective. The city engineer may amend the standards from time to time, upon the recommendation of the planning commission to city council, and such amendment shall be filed with the city secretary at least ten days before it becomes effective.
The Drainage and Erosion Control Design Manual (DCM) is intended to establish uniform design practices for the design and construction of storm drainage and erosion control in New Braunfels and its extraterritorial jurisdiction. The DCM is specified in Section 143-2(b) of the City of New Braunfels Code of Ordinances as part of the official stormwater management plan. The manual neither replaces the need for engineering judgment nor precludes the use of information not presented in the manual.
The following amendments are proposed to the DCM:
1. Section 2.1.4 - Specify requirements for Preliminary Drainage Report.
2. Section 2.1.5 - Specify requirements for Master Drainage Plan Report.
3. Section 2.5 - Specify that the elevation of the lowest floor shall be elevated to 10 inches above finished grade of the surrounding ground (in previous DCM).
4. Section 2.5 - Specify that the elevation of the lowest floor shall be elevated to 12 inches above adjacent stormwater conveyance structures (clarification).
5. Section 2.5 - Require and specify grading plan required at plat and building permit.
6. Section 2.5 - Specify that residential lots shall be graded to avoid water flowing over curb and driveway, and out of right-of-way.
7. Section 2.7 - Specify that if development activity changes runoff characteristics that creates point discharge or any increase in discharge rates or velocities, the flow shall outfall into right-of-way or drainage easement that has capacity and an impact analysis is required to verify capacity and no adverse impact.
8. Section 2.7 - Specify engineered retaining walls greater than three feet shall be designed to prevent freefall of stormwater.
9. Section 2.11 - Specify pumped drainage facilities design, maintenance and operations requirements.
10. Section 2.11 - Require feasibility analysis of pumped detention prior to permit application.
Staff presented the proposed amendments to area development engineers on March 23, 2017 and to the Watershed Advisory Committee (WAC) on May 25, 2017 with the exception of amendments to Section 2.7. Comments were considered in the development of the proposed amendments. Staff presented all the items to Planning Commission on June 6, 2017 and a recommendation was made at the July 5, 2017 meeting.
ADDRESSES A NEED/ISSUE IN A CITY PLAN OR COUNCIL PRIORITY:
N/A
FISCAL IMPACT:
N/A
Recommendation
COMMITTEE RECOMMENDATION:
Staff presented the amendments to the Watershed Advisory Committee on May 25, 2017; however, the WAC did not have a quorum and not action was taken. The Planning Commission recommended approval of the amendments to the City of New Braunfels Drainage and Erosion Control Design Manual on a motion that carried unanimously.
STAFF RECOMMENDATION:
Staff recommends approval of the proposed amendments to the City of New Braunfels Drainage and Erosion Control Design Manual.