Drainage Guidelines & Requirements
Haltom City's stormwater/drainage requirements for any development (not just new development) are located in various locations in the City's Code of Ordinances and the City's Subdivision Ordinance. Owners, developers, applicants, engineers, contractors, etc. are encouraged to review the following locations in regards to the stormwater/drainage requirements that are applicable to their development project:
Code of Ordinances, Section 86-182: "Minimum Control Requirements"
All stormwater management practices shall be designed so that the specific storm frequency storage volumes (e.g., water quality, channel protection, ten-year, one-hundred-year) as identified in the current drainage design manual are met, unless the city engineer grants a waiver or the owner is exempt from such requirements. If hydro-logic or topographic conditions warrant greater control than that provided by the minimum control requirements, the city engineer may impose any additional requirements deemed necessary to control the volume, timing, and rate of runoff.
(Ord. Number O-2012-003-011, § 1, 2-13-12)
Code of Ordinances, Section 86-186: "Structural Stormwater Practices"
Owners are required by the city to implement structural measures to reduce runoff volumes and velocities at sites where downstream infrastructure is insufficient to accommodate developed flows. The following methods shall be considered appropriate for consideration as structural stormwater practices:
- Swales and channels;
- Culverts, inlets and pipes;
- Energy dissipaters;
- Infiltration trenches;
- Stormwater ponds;
- Porous surfaces; and
- Re-use (rain harvesting, etc.)
(Ord. Number O-2012-003-011, § 1, 2-13-12)
Haltom City Subdivision Ordinance, Section 21-104: "Sheet No. 2 - Topography, Street, & Drainage Plan"
This sheet may be prepared on a reproducible copy of Sheet Number 1 so that the same information will be repeated together with the following:
- Topographical information including contour lines on a basis of two(2') foot intervals. All elevation shall be on U.S. Coast and Geodetic Survey datum or referenced to a City benchmark on the same datum. The datum used shall be specified on the drawing.
- Any proposed changes in topography are shown by contour lines on a basis of five feet vertical interval in terrain.
- Areas contributing drainage to the proposed subdivision shall be shown on small-scale supplemental drawings. The information to be submitted shall include the area, slope and type of development, and quantity of drainage in the contributing area.
- At points where drainage enters or leaves the proposed subdivision the following information shall be provided: a. location of entrance and discharge points b. DA (Drainage Area) c. 25 d. Q100All drainage must be planned in the best interests of the immediate and adjacent properties. Any present adverse "drainage situations" shall not be made any worse than existing.
- Drainage arrows shall be shown for all streets and drainage easements. When the maximum permissible capacity of streets to carry stormwater has exceeded the location of storm sewers, curb inlets, open channels, and other drainage facilities shall be shown.
- Supplemental information showing the preliminary design calculations for drainage shall be furnished and attached to the Topography and Drainage Plan. Calculations shall conform to the current design criteria adopted by the City. Areas subject to flooding shall be shown, delineating the 100-year flood limits if applicable.
- The exact location, dimension, description, and flow line of existing drainage structures and the location, flow line, flood plain, and floodway of existing water courses within the subdivision or contiguous tracts.
- The width of surfacing measured from back-to-back of curbs shall be Page 28shown for all streets. The width of drainage and other easements shall be shown.
- The responsible entity for the operation and maintenance of any building, park, equipment, pools, plantings, lawns or other legal interests if it is proposed that they are to be shared by owners of the real property within the subdivision.
Haltom City Subdivision Ordinance, Section 28-105: "Storm Drainage Plans"
- A plan and profile of proposed storm sewers or channels, showing hydraulic data, pipe grades and sizes, manholes, inlets, pipe connections, outlet structures, etc., in conformance with the criteria as shown in Part XI of this Ordinance and the Standard Details adopted by the City Council. Each plan shall show the seal and signature of the registered professional civil engineer who prepared the plans. Each sheet shall include north point, scale, date, and benchmark description to sea level datum.
- A general location map of the subdivision showing the entire watershed (a USG.S. quadrangle is satisfactory).
- Calculations showing the anticipated stormwater flow, including watershed area,% runoff, and time of concentrations shall be submitted showing basis for design for a Q25 and Q100 storm.
- Detailed plans shall be submitted for any bridges, culverts, catch basins, any other drainage structures, or any other improvements to be made. Page 375. Any existing adverse "drainage situations" shall not be made any worse than existing.
Haltom City Subdivision Ordinance, Section 42-102: "Drainage Easements"
Easements for storm drainage facilities shall be provided at locations Page 58 containing proposed or existing drainage ways.
- Storm drainage easements of twenty feet minimum width shall be provided for existing and proposed enclosed drainage systems. Easements shall be centered on the systems, unless otherwise approved by the City Engineer. Larger easements, where necessary, shall be provided as follows: Pipe Size Width of Easement 30 inches through 42 inches 25 feet 48 inches through 60 inches 30 feet
- Storm drainage easements along proposed or existing open channels shall provide sufficient width for the required channel designed for "fully developed conditions" and such additional width, fifteen feet (15')minimum, as may be required to provide ingress and egress for maintenance equipment; to provide clearance from fences and space for utility poles; to allow maintenance of the channel bank; and to provide adequate slopes necessary along the bank. Adequate slopes for natural channels is defined as 4:1 (run:rise); natural slopes steeper than this will only be permitted when approved by the appropriate public works maintenance division.
- Storm drainage easements shall be provided for emergency overflow drainage ways of sufficient width to contain within the easement stormwater resulting from a 100-year frequency rain event based on "fully developed conditions."
- The storm drainage facilities indicated in 43-103(b) and 43-103(c) of above shall be designed with one foot (1') of "free-board"; however, if this one foot of "free-board" increases the capacity of the storm drainage facility by a factor greater than "1.25 X the capacity required for the discharge from a fully developed 100-year rain event", then the storm drainage facility shall be designed to have "free-board" up to the"1.25 X the capacity required for the discharge from a fully developed100-year rain event" elevation.
The width of the easements described in Items (a) through (d) above shall be substantiated by a drainage study and drainage calculations or other criteria submitted to and approved by the City Engineer.
Haltom City Subdivision Ordinance, Article 49: "Storm Drainage Facilities"
General Drainage facilities shall be provided and constructed by the subdivider or developer in accordance with current design criteria adopted by the City and the Haltom City Standard Specifications for Street and Drainage Construction and the following basic requirements:
- When conditions upstream from a proposed channel or storm drain outside the limits of the ownership of the subdivider or developer do not permit maximum design flow, the drainage facilities shall be designed based on potential and fully developed conditions.
- When conditions downstream from a proposed channel or storm drain outside the limits of the ownership of the subdivider or developer do not permit maximum design flow, water surface elevations for a 100-year design frequency shall be indicated considering the downstream condition in order to define the potential flood hazards. Solutions to protect the property shall be developed.
- All drainage improvements shall be designed to an acceptable outfall.
- Where there is a question as to the justification or size of drainage facilities, doubt will be resolved in favor of additional drainage capacity.
- The combined capacity of the storm drain pipe, street and surface drainage shall contain the 100-year design flow at the R.O.W. lines. The finish floor elevation shall be at least one foot above the 100-year flood Base Flood Elevation (BFE).
- The developer shall install an underground storm drain beginning at the point where the calculated storm water runoff is of such a quantity two feet (2') Page 65th that it will overflow the street at curb height. The storm drain shall be constructed from this point to an approved outlet where the stormwater can be discharged safely without damage or flooding of adjacent property.
- The developer may install a concrete-lined channel in lieu of installing pipe larger than sixty inches (60"). When the pipe required to meet these subdivision regulations is less than sixty inches, the flow from this rain event must be carried in such a pipe. When an open channel is necessary, it shall be at the rear of residential lots and meet the requirements of Sections 42-102 and 42-103. In the event it is necessary to locate the drainage facility adjacent to and parallel to a street it shall be a closed conduit even though pipe sizes larger than sixty inches (60") are required.
- A permanent six-foot chain link fence or other fence meeting the requirements of the City shall be constructed to enclose the channel area where it is adjacent to residential lots and also in other cases where it is deemed necessary to restrict access to the channel.
- All drainage facilities shall be constructed on public right-of-way or easements dedicated for the purpose. Drainage easements shall be of sufficient size to permit access for maintenance of the drainage facility.
- When a drainage ditch or storm drain pipe, culvert or bridge is proposed, calculations shall be submitted showing basis for design.
- When a drainage channel, storm drain pipe, culvert or bridge is proposed, completed plans, profiles and specifications shall be submitted, showing complete construction details and detailed cost estimate.
- The subdivider or developer shall indicate present DA's I25, I100, Q25 and Q100.
- The subdivider or developer shall indicate proposed DA's I25, I100, Q25 and Q100.
- The subdivider or developer shall indicate both present and proposed contours and direction of drainage.
- Any present adverse drainage problems shall not be made worse.
- Proposed drainage shall flow to drainage easements, storm drain facilities and/or publicly dedicated streets only.
- Existing capacities of drainage easements, storm drain facilities and/or publicly dedicated streets shall be indicated.
- Existing capacities of drainage easements, storm drain facilities and/or publicly dedicated streets shall not be exceeded.
- Directing or allowing drainage onto private property will not be allowed.
Drainage requirements shall be based on the Rational Method of Design (Q = CIA).
Q = Discharge or surface runoff in cubic feet per second.
C = Coefficient of runoff
- 0.35 for parks and undeveloped areas
- 0.50 for single-family or duplex residential areas
- 0.80 for multi-family residential areas
- 1 for paved, commercial, and industrial areas
I = Intensity of runoff in inches per hour.
A = Drainage areas in acres.
A minimum time of concentration of ten minutes shall be used, with detailed computation made to determine the exact time of concentration to each inlet facility.
Design Storm Frequency
|Type of Facility (x)||Description of Area to be Drained||Maximum Allowable Time of Concentration (Minutes)||Recommended Design Frequency (Years)|
|Storm Sewers||Residential, Commercial and Manufacturing||20||25|
|Culverts, Bridges, Channels and Creeks||Any type of area less that 100 acres||30||100|
|Culverts, Bridges, Channels and Creeks||Any type of area greater that 100 acres but less than 1,000 acres||45||100|
|Culverts, Bridges, Channels and Creeks||Any type of area greater that 1,000 acres||60||100|
- (x) In all cases, the discharge from a 100-year rain event for "fully developed conditions" shall be completely carried within a drainage easement and/or R.O.W.
- The previous information/hyperlinks are not intended to be an all-encompassing list of Haltom City's stormwater/drainage requirements. Rather, the above is provided as an aide for owners, developers, applicants, engineers, and contractors, who are looking for a quick guide/reference.