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(a) Definitions. The following definitions are applicable to the floodplain regulations in this article:
(1) AREA OF SPECIAL FLOOD HAZARD means the land in the floodplain within a community that is subject to a one percent or greater chance of flooding in any given year.
(2) BASEMENT means any area of a building, including any sunken room or sunken portion of a room, having its floor below ground level (subgrade) on all sides.
(3) BASE FLOOD means the flood event having a one percent chance of being equaled or exceeded in any given year.
(4) BASE FLOOD ELEVATION means the water surface elevation from a flood event having a one percent chance of being equaled or exceeded in any given year, which is shown on the flood insurance rate map (FIRM) and in the accompanying flood insurance study (FIS) for Zones A, AE, AH, A1 - A30, AR, V1-V30, or VE, or on the regulatory floodplain maps.
(5) DESIGN FLOOD (City's Design Standard) means the 100-year frequency (one percent chance of being equaled or exceeded in any given year) flood discharge as calculated for fully developed watershed conditions.
(6) DEVELOPMENT means any manmade change in improved and unimproved real estate, including but not limited to the construction of buildings or other structures, mining, dredging, filling, grading, paving, excavation, drilling operations, or storage of equipment or materials unless approved by the city on a temporary basis in connection with authorized construction activities.
(7) ENVIRONMENTALLY SIGNIFICANT AREA means an area in the floodplain:
(A) containing endangered species of either flora or fauna;
(B) which is a geologically similar area, as defined in Division 51A-5.200, "Escarpment Regulations," of this article;
(C) identified as wetlands or waters of the United States; or
(D) determined to be an archaeological or historic site.
(8) EQUAL CONVEYANCE REDUCTION means the ability of the property on the opposite side of the stream to construct a project that alters conveyance by the same amount as the proposed fill permit or floodplain alteration permit project.
(9) EXISTING MANUFACTURED HOME PARK means a manufactured home park or subdivision for which the construction of facilities for servicing the lots was completed before March 16, 1983, the effective FIRM date.
(10) FEDERAL EMERGENCY MANAGEMENT AGENCY (FEMA) means the federal agency responsible for administering the National Flood Insurance Program (NFIP).
(11) FILL PERMIT means the process of reclaiming a portion of land in the floodplain to create a developable area including but not limited to a habitable structure or parking area, raising any area of land out of a floodplain area on fill, or creating an area that can be developed in the future. The fill permit process removes the floodplain (FP) designation and is applicable in areas with an upstream drainage area greater than 100 acres, even if the land has not been formally designated as an FP area.
(12) FIVE HUNDRED YEAR FREQUENCY FLOOD (500-YEAR FLOOD) or 0.2 PERCENT ANNUAL CHANCE EXCEEDANCE PROBABILITY FLOOD EVENT means the flood event having a 0.2 percent chance of being equaled or exceeded in any given year. The 500-year flood in Dallas is based upon fully developed land uses within the watershed as defined by the current zoning designation.
(13) FLOOD OR FLOODING means a general and temporary condition of partial or complete inundation of normally dry land areas from the unusual and rapid accumulation or runoff of surface waters from any source.
(14) FLOOD INSURANCE RATE MAP (FIRM) means an official map of a community on which the Federal Emergency Management Agency (FEMA) has delineated the areas of special flood hazards and the insurance risk premium zones applicable to the community.
(15) FLOOD INSURANCE STUDY (FIS) means the official report provided by FEMA containing flood profiles, water surface elevation of the base flood, and the Flood Boundary-Floodway Map.
(16) FLOODPLAIN (FP) means any land area susceptible to inundation by the design flood, even if the land has not been formally designated as an FP area on the Regulatory Floodplain Maps.
(17) FLOODPLAIN ALTERATION means the construction of uninhabitable structures, alterations to existing structures within a floodplain area complying with Section 51A-5.104(b), mining, dredging, filling, grading, or excavation in the floodplain that does not remove or alter an FP designation. (Examples include, but are not limited to, the construction of a tennis court, a playground, a gazebo, a swimming pool, a fence, a deck, an erosion control wall, or the installation of significant landscaping.)
(18) FLOODPLAIN OR FP ADMINISTRATOR means the director of water utilities, who is responsible for administering the federal flood insurance program, or the director's designated representative.
(19) FLOODPROOFING means any combination of structural and non-structural additions, changes, or adjustments to structures that reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, or structures and their contents. If floodproofing is utilized, the design must be certified by a licensed professional engineer.
(20) FLOODWAY (OR REGULATORY FLOODWAY) means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the design flood without cumulatively increasing the water surface elevation more than a designated height.
(21) FLOODWAY EASEMENT means a drainage area dedicated to the city as an easement to prevent obstructions of floodway capacity in a floodplain.
(22) FUNCTIONALLY DEPENDENT USE means a use that cannot perform its intended purpose unless it is located or carried out in close proximity to water. This term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and shipbuilding and ship repair facilities, but does not include long-term storage or related manufacturing facilities.
(23) HABITABLE STRUCTURE means any structure with electric, heat, or plumbing that can be used for living, sleeping, eating, or assembly purposes.
(24) HIGHER STANDARDS means community requirements that exceed the minimum FEMA standards for participating in the National Flood Insurance Program (NFIP).
(25) INTERIOR DRAINAGE AREAS means the geographical areas that act as a watershed for the sumps.
(26) LETTER OF MAP CHANGE (LOMC) means a letter that reflects an official change in an effective Flood Insurance Rate Map (FIRM). LOMCs are issued in response to a request to FEMA to revise or amend its effective flood map to remove a property or reflect changed flooding conditions on the effective map and can include Letter of Map Revisions (LOMRs), Letter of Map Amendments (LOMAs), and Letter of Map Revisions based on Fill (LOMR-F's) as amended by FEMA.
(27) LEVEE means a manmade structure (usually an earthen embankment) designed and constructed in accordance with sound engineering practices to contain, control, or divert the flow of water for protection from temporary flooding.
(28) LEVEE SYSTEM means a flood protection system consisting of a levee or levees and associated structures accredited by FEMA pursuant to 44 CFR 65, as amended, such as closure and drainage devices constructed and operated in accordance with sound engineering practices.
(29) LICENSED PROFESSIONAL ENGINEER means a person who is duly licensed and registered to engage in the practice of engineering in the State of Texas in accordance with state law.
(30) LOWEST ADJACENT GRADE means the lowest point of the ground level immediately next to a building.
(31) LOWEST FLOOR means the lowest floor of the lowest enclosed area of a building (including its basement). An unfinished or flood resistant enclosure that is useable solely for parking of vehicles, building access, or storage in an area other than a basement area, is not considered a building's lowest floor.
(32) MANUFACTURED HOME means a structure, transportable in one or more sections, that is built on a permanent chassis and designed for use with or without a permanent foundation when connected to the required utilities. In this article only, the term "manufactured home" includes park trailers, travel trailers, and similar vehicles placed on a site for more than 90 consecutive days, but does not include recreational vehicles.
(33) MANUFACTURED HOME PARK OR SUBDIVISION means a parcel (or contiguous parcels) of land divided into two or more manufactured home lots for rent or sale.
(34) NATIONAL FLOOD INSURANCE PROGRAM (NFIP) means the federal program administered by FEMA that enables property owners to purchase flood insurance against damage to or loss of property resulting from a flood.
(35) ONE HUNDRED YEAR FREQUENCY FLOOD (100-year flood) or ONE-PERCENT ANNUAL CHANCE EXCEEDANCE PROBABILITY FLOOD EVENT means the flood event having a one percent chance of being equaled or exceeded in any given year. The 100-year flood in Dallas is based upon fully developed land uses within the watershed as defined by the current zoning designation.
(36) POOL-RIFFLE SEQUENCES mean the alternating deep and shallow flow conditions caused by a moving, nonuniform channel grade.
(37) REGULATORY FLOODPLAIN MAPS means the most updated floodplain maps available, as accepted by the City of Dallas, regardless of adoption by FEMA. These include, but are not limited to, maps resulting from floodplain update studies, Letter of Map Revisions (LOMRs), and floodplain studies resulting from current and proposed construction projects.
(38) SEEP means a location where natural groundwater makes its way in a non-continuous flow to the surface, creating a wet soil condition.
(39) SPECIAL EXCEPTION means a grant of relief to a property owner permitting reconstruction in a manner otherwise prohibited by this division.
(40) STANDARD PROJECT FLOOD means the flood caused by the most severe combination of meteorological and hydrological conditions reasonably characteristic of the region. The standard project flood is defined by the U.S. Army Corps of Engineers for use in major flood control projects.
(41) STRUCTURE means, for purposes of this division, a walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured home.
(42) SUBSTANTIAL DAMAGE means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.
(43) SUBSTANTIAL IMPROVEMENT means any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market or tax appraisal value of the structure, whichever is greater, as determined by an independent appraiser or the last official City tax roll, either before the improvement or repair is started, or, if the structure has been damaged and is being restored, before the damage occurred. For the purpose of this definition "substantial improvement" occurs when the first alteration of any wall, ceiling, floor, or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure. The term does not, however, include any project for improvement of a structure for the sole purpose of complying with federal, state, or local health, sanitary, or safety code specifications which have been identified in writing by the local code enforcement official as necessary to assure safe living conditions prior to the start of the proposed improvement, or any alteration of a historic structure as defined by FEMA. See Section 51A-5.104(b)(2) for city of Dallas limitations.
(44) SUMPS mean drainage features of levee systems that temporarily store storm water runoff before it is conveyed to a river system by pumping over or draining through a levee.
(45) SWALES mean low lying areas in the floodplain that convey flood waters when flow exceeds channel capacity.
(46) VALLEY STORAGE means the measure of a stream's ability to store water as it moves downstream.
(47) VARIANCE means a grant of relief by a community from the terms of a floodplain management regulation.
(48) WATER SURFACE ELEVATION means the height, in relation to the North American Vertical Datum (NAVD), of floods of various magnitudes and frequencies in the floodplain.
(b) Interpretations. The intent of this division is to equal or exceed the minimum federal criteria for participation in the National Flood Insurance Program, located in 44 Code of Federal Regulations, Chapter I, Part 60.3, as amended; and FEMA 480, as amended. All higher standards and FEMA minimum standards apply. The City of Dallas must also enforce any more restrictive state requirements. The City of Dallas has exceeded the minimum standards by adopting more comprehensive floodplain management regulations. In some instances, community officials may have access to information or knowledge of conditions that require, particularly for human safety, higher standards than the minimum NFIP criteria. Any floodplain management regulations adopted by a state or community that are more restrictive than the criteria set forth in the NFIP regulations take precedence. All FEMA minimum standards in the Code of Federal Regulations also apply. (Ord. Nos. 19455; 19786; 20360; 24085; 27318; 27572; 27697; 27893; 30994; 31314; 32039)
(a) In general.
(1) A floodplain designation is not a zoning classification, but refers to a specific area subject to flooding.
(2) When an FP designation is noted by an "FP" prefix on the official zoning district map, or on the FEMA effective maps, the area designated is referred to in this article as an FP area.
(3) FP areas include those areas:
(A) identified as special flood hazards by FEMA in the:
(i) current scientific and engineering report entitled, "The Flood Insurance Study (FIS) for Dallas County," dated March 21, 2019, with accompanying Flood Insurance Rate Maps and/or Flood Boundary-Floodway Maps (FIRM and/or FBFM) dated March 21, 2019, and any revisions thereto are hereby adopted by reference and declared to be a part of this paragraph,
(ii) current scientific and engineering report entitled, "The Flood Insurance Study (FIS) for Rockwall County," dated September 26, 2008, with accompanying Flood Insurance Rate Maps and/or Flood Boundary-Floodway Maps (FIRM and/or FBFM) dated September 26, 2008, and any revisions thereto are hereby adopted by reference and declared to be a part of this paragraph,
(iii) current scientific and engineering report entitled, "The Flood Insurance Study (FIS) for Collin County," dated June 7, 2017, with accompanying Flood Insurance Rate Maps and/or Flood Boundary-Floodway Maps (FIRM and/or FBFM) dated June 7, 2017, and any revisions thereto are hereby adopted by reference and declared to be a part of this paragraph,
(iv) current scientific and engineering report entitled, "The Flood Insurance Study (FIS) for Denton County," dated April 18, 2011, with accompanying Flood Insurance Rate Maps and/or Flood Boundary-Floodway Maps (FIRM and/or FBFM) dated April 18, 2011, and any revisions thereto are hereby adopted by reference and declared to be a part of this paragraph, or
(v) current scientific and engineering report entitled, "The Flood Insurance Study (FIS) for Kaufman County," dated July 3, 2012, with accompanying Flood Insurance Rate Maps and/or Flood Boundary-Floodway Maps (FIRM and/or FBFM) dated July 3, 2012, and any revisions thereto are hereby adopted by reference and declared to be a part of this paragraph, and
(B) other areas that the director of Dallas Water Utilities has identified as flood risk areas.
(4) The floodplain administrator shall regulate according to both the FEMA effective maps and the regulatory floodplain maps, regardless of adoption by FEMA. The floodplain administrator shall notify the director of development services of all map updates.
(b) Initiation. The addition to or removal from the official zoning district map of an FP prefix may be initiated in the following ways:
(1) An owner of property located within an FP area may apply for the review of an FP designation based upon evidence of a mapping error provided by the owner.
(2) The director of water utilities may, upon his or her own initiative, review the status of an FP designation.
(3) An owner of property located within an FP area may apply for a fill permit and removal of the FP prefix by following the procedure outlined in Section 51A-5.105.
(c) Engineering studies. Hydraulic and hydrologic engineering studies or a field survey must support any changes to an FP designation. The engineering study must be signed and sealed by a licensed professional engineer. The director may require geotechnical core borings as part of his or her investigations under this subsection.
(d) Decision on designation. The director of water utilities shall make a final decision on whether to add or remove an FP prefix on the official zoning district map only after the director determines that engineering studies support the change in the FP designation.
(e) Zoning map revision. The director of water utilities must notify the director of development services in writing that an FP prefix is to be removed from or added to the official zoning district map. The written notification must contain a description of the property affected and the reasons why the FP prefix is being changed.
(f) Letter of Map Change (LOMC). A letter of map change from FEMA is required for removal of an FP prefix from the official zoning map if the area is designated as a flood hazard area on the FIRM. (Ord. Nos. 19455; 19786; 21299; 22920; 24085; 25047; 25716; 27318; 27551; 27697; 27893; 28164; 28671; 29359; 30481; 30994; 31109; 32002; 32039)
(a) A person shall comply with the requirements of this article for FP areas before developing land within the design flood line of a creek or stream having a contributing drainage area of 100 acres or more, even if the land has not been formally designated as an FP area.
(b) Except as provided in Subsection (c), alterations of the natural floodplain in areas with less than 100 acres must comply with the Dallas Development Code and city drainage standards but are not subject to the engineering requirements for filling in Section 51A-5.105(g).
(a) Except as provided in this section, the urban forest conservation requirements in Division 51A-10.130 apply. Protected trees removed in the floodplain are not subject to exceptions to Article X.
(b) A person commits an offense if he removes or injures any vegetation within a floodplain.
(c) It is a defense to prosecution under Subsection (b) if the act is:
(1) authorized in advance in writing by the director of water utilities;
(2) in conformance with a landscape plan approved by the director of water utilities;
(3) routine maintenance of vegetation such as trimming or cutting designed to maintain the healthy or attractive growth of the vegetation; or
(a) Uses permitted. To allow for the appropriate development of land that is subject to flooding without unduly endangering life and property, the following uses are permitted in an FP area provided they are permitted in the underlying zoning district and comply with the requirements of Section 51A-5.105(g) and all applicable elevation requirements of the Federal Emergency Management Agency:
(1) Farm or ranch (excluding habitable structures).
(2) Utility services, electrical substation, detention basin, water reservoir or pumping station, and water treatment plant.
(3) Sanitary landfill and refuse transfer station.
(4) Public park or playground and golf course (excluding habitable structures).
(5) Commercial amusement (outside) approved by specific use permit.
(6) Helistop approved by specific use permit.
(7) Radio, television, or microwave tower, amateur communications tower, and tower/antenna for cellular communication.
(b) Improvements permitted.
(1) Structures. An uninhabitable structure customarily associated with a use listed in Subsection (a) may be constructed within an FP area only if the director of water utilities determines that the proposed structure meets the same engineering requirements applicable to filling in Section 51A-5.105(g) and issues a floodplain alteration permit.
(2) Improvements. The owner of a structure in an FP area shall not make any improvements to the structure without first obtaining approval from the director of water utilities. The director of water utilities may approve proposed improvements if the cumulative value of all improvements for the previous five years is less than 50 percent of the market or tax appraisal value of existing improvements on the property, whichever is greater. No substantial improvements are permitted. Improvement values are calculated per guidelines outlined in FEMA P-758 as revised. All improvements must comply with the requirements of Section 51A-5.105(g), including additions. Substantially damaged structures are considered substantial improvements.
(3) Completion of vested structures. The building official shall not withhold a final inspection or certificate of occupancy for a structure in an FP area if building permits for the structure were issued by the building official before FEMA's FIRM becomes effective designating such areas as A or AE, and the structure otherwise complies with all applicable requirements.
(4) Board of adjustment. The board of adjustment may only grant a special exception to allow the reconstruction of a structure in an FP area if the structure is a historical structure as defined by FEMA, or the property is zoned for a functionally dependent use. The board may grant a special exception upon a showing of good and sufficient cause and a determination that the reconstruction will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public, or conflict with other local, state, or federal laws. The reconstructed structure must be protected by methods that minimize flood damage. The board may not grant a special exception to authorize reconstruction within any designated floodway if any increase in flood levels during the base flood discharge would result. Any special exception granted must be the minimum necessary, considering the flood hazard, to afford relief. The reconstruction of a structure in an FP area may not increase the lot coverage of the structure.
(A) The director of water utilities shall notify in writing the owner of a structure in an FP area that:
(i) the granting of a special exception to reconstruct the structure below the base flood level will result in increased premium rates for flood insurance that will be commensurate with the increased risk; and
(ii) the construction below the base flood level increases risks to life and property. The notification letter must be maintained with the record of the board's action.
(B) The FP administrator shall maintain a record of all actions involving applications for special exceptions and shall report special exceptions to FEMA upon request.
(5) Parking.
(A) Surface parking. All surface parking spaces must be constructed at a minimum elevation of two feet above the design flood elevation.
(B) Underground parking garages. The entrance elevation and any openings on underground parking garages constructed within or adjacent to a flood prone area may not be lower than two feet above the design flood elevation.
(C) Parking on piers. Parking lots elevated on piers such that the low chord is two feet above the design flood elevation are permitted if all engineering requirements for filling in Section 51A-5.105(g) are met, and do not violate any other part of the Dallas Development Code. A habitable structure may not be placed on piers.
(D) Parking in interior drainage (sump) areas. All surface parking spaces within an interior drainage area must be constructed at a minimum elevation of one foot above the design flood elevation.
(6) Storage in the floodplain is prohibited.
(A) A person shall not place, store, or maintain a shipping container, trailer, boat, inoperable vehicle, recreational vehicle, construction materials, waste materials, hazardous materials, or construction equipment in the floodplain. For purposes of this paragraph, the term "vehicle" includes but is not limited to automobiles, buses, and recreational vehicles. It is a defense to prosecution that the placement, storage, or maintenance of shipping containers, trailers, boats, inoperable vehicles, recreational vehicles, construction materials, waste materials, hazardous materials, or construction equipment is otherwise permitted by or in connection with a valid federal, state, county, or city permit, or is otherwise authorized by those entities.
(B) The director of water utilities shall give written notice and allow persons in violation of Subparagraph (A) a period of 90 days to come into compliance.
(7) Manufactured homes. Manufactured homes may not be placed within a floodplain area. Recreational vehicle camping and parking locations are not permitted within a floodplain area.
(8) Fences. Fences must comply with all applicable construction codes at the time of construction.
(A) Fences are not permitted within floodway easement areas without engineering analysis addressing Section 51A-5.105(g), regardless of fence type.
(B) Except as provided in this paragraph, fences in a floodplain area not designated as a floodway easement must be:
(i) constructed of wrought iron;
(ii) constructed with a one-foot gap along the bottom if located in areas where flooding is less than three feet of depth; or
(iii) constructed using flood vents, as outlined in the NFIP Technical Bulletin 1, as amended, if located in areas where flooding is greater than one foot and less than four feet of depth.
(C) Fences in a floodplain area not designated as a floodway easement that do not comply with Subparagraph (B) must be analyzed as an obstruction for compliance with Section 51A-5.105(g).
(c) Construction standards. All improvements and construction permitted in an FP area must comply with the following requirements:
(1) Structures must be:
(A) securely anchored to the foundation and otherwise designed to prevent flotation and collapse during inundation; and
(B) designed to prevent damage to nonstructural elements during inundation.
(2) Thermal insulation used below the first floor level must be of a type that does not absorb water.
(3) Adhesives must have a bonding strength that is unaffected by inundation.
(4) Doors and all wood trim must be sealed with a water-proof paint or similar product.
(5) Electrical, heating, ventilation, plumbing, air-conditioning equipment, and other mechanical service facilities must be designed and located at least three feet above the design flood elevation to prevent water from entering or accumulating in the components during flooding.
(6) Transportation systems such as elevators and escalators must be protected from flooding, and enclosures must be safe from flooding and protect life safety. See Code of Federal Regulations Title 44, Part 60.3 and the NFIP Technical Bulletin 4 as amended for more information.
(7) Basements.
(A) Basements are permitted only in nonresidential construction and only if they are designed to preclude inundation by the design flood level, either by:
(i) locating any exterior opening at least three feet above the level of the design flood elevation; or
(ii) using water-tight closures, such as bulkheads and flood shields.
(B) All basements must be constructed so that any enclosure area, including utilities and sanitary facilities below the flood-proofed design level, is watertight with impermeable walls.
(C) Basement walls must be built with the capacity to resist hydrostatic and hydrodynamic loads and the effects of buoyancy resulting from flooding to the flood-proofed design level so that minimal damage will occur from floods that exceed the flood-proofed design level.
(D) The area surrounding the structure must be filled to or above the elevation of the design flood. The fill must be compacted, and slopes must be protected by vegetative cover.
(E) Basements must be designed by a licensed professional engineer.
(F) Basement ceilings must consist of a sufficient wet strength and be installed to survive inundation.
(8) Plywood used at or below the first floor level must be of an "exterior" or "marine" grade and of a water-resistant or waterproof variety.
(9) Wood flooring used at or below the first floor level must be installed to accommodate a lateral expansion of the flooring, perpendicular to the flooring grain, without incurring structural damage to the building.
(10) Paints or other finishes used at or below the first floor level must be capable of surviving inundation.
(11) All air ducts, large pipes, and storage tanks located at or below the first floor level must be firmly anchored to prevent flotation.
(12) Tanks must be vented at a location above the 100-year flood level.
(d) 500-year frequency flood. All new construction located in a 500-year frequency flood zone must comply with the following:
(1) Building pad site must be filled to an elevation of at least two feet above the 100-year flood elevation.
(a) Permit required.
(1) A person shall not deposit or store fill, place a structure, excavate, or engage in any other development activities in an FP area without first obtaining:
(A) a fill permit or a floodplain alteration permit from the director of water utilities; and
(B) all other permits required by county, state, and federal agencies.
(2) A fill permit allows the property to be developed at a specified elevation in compliance with this section.
(3) The director of water utilities shall maintain a record of all fill permits and floodplain alteration permits.
(b) Floodplain alteration permit process.
(1) The director of water utilities may issue a floodplain alteration permit if he or she determines that:
(A) the alteration does not remove an FP designation; and
(B) the alteration complies with all applicable engineering requirements in Subsection (g).
(2) The floodplain alteration permit may require hydrologic or hydraulic modeling as determined by the director of water utilities. Examples of situations that may require hydrologic or hydraulic modeling include, but are not limited to:
(A) A pool, tennis court, patio, cook area, deck, or other outdoor amenity above existing grade, but not above the base flood elevation.
(B) A fence that will block the flow of flood water during the 100-year flood event.
(C) A retaining wall projecting into the channel as compared to the existing grade.
(D) Elevated utilities that block the flow of flood water during the 100-year flood event.
(E) Additions to existing structures.
(c) Initiation of the fill permit process. An applicant for a fill permit shall submit an application to the director of water utilities on a form approved by the director and signed by all owners of the property.
(d) Preapplication conference.
(1) An applicant for a fill permit or a floodplain alteration permit that will require hydrologic or hydraulic modeling shall request a preapplication conference with representatives from the department of water utilities.
(2) At the preapplication conference, the director of water utilities shall determine what information is necessary for a complete evaluation of the proposed fill project. The applicant may be required to submit all necessary information, including, but not limited to the following:
(A) A vicinity map.
(B) The acreage figures for the entire tract, the area located in the floodplain, and the area proposed to be filled.
(C) A description of existing and proposed hydrologic and hydraulic analysis conducted.
(D) Plans that comply with the Landscape and Urban Forest Conservation Regulations in Article X of the Dallas Development Code, as amended.
(E) A table of values for analysis of the engineering criteria listed in Subsections (h)(1), (h)(2), and (h)(5).
(F) A water surface profile.
(G) A plan view showing existing and proposed contours and grading.
(H) Plotted cross-sections.
(I) An overall map of the project area.
(J) Drainage area map.
(e) Filling to remove an FP designation.
(1) In general. This subsection applies to applications to remove an FP designation from any regulatory floodplain.
(2) Review of application by departments.
(A) If the application is to remove an FP designation, the director of water utilities shall forward copies of the application to the director of development services, the chief planning officer, and the director of park and recreation for review.
(B) The director of development services, the chief planning officer, and the director of park and recreation shall review the application and advise the director of water utilities of the environmental impacts of the project, zoning concerns, or other concerns. If concerns are raised by one of these departments, the concerns must be addressed by the property owner prior to issuance of the fill permit. These departments shall also determine whether the applicant's property should be considered for public acquisition due to its ecological, scenic, historic, or recreational value.
(3) Neighborhood meeting. The water utilities department shall schedule and conduct a virtual or in-person neighborhood meeting on each application. The applicant or the applicant's representative must attend the neighborhood meeting. The director shall send written notice of the meeting to the applicant, to all owners of real property within 500 feet from the boundary of the subject property, and to persons and organizations on the early notification list on file with the department of development services. Measurements include the streets and alleys. The notice must be given not less than 10 days before the date set for the neighborhood meeting by depositing the notice properly addressed and postage paid in the United States mail to the property owners as evidenced by the last approved city tax roll. This notice must be written in English and Spanish if the area of request is located wholly or partly within a census tract in which 50 percent or more of the inhabitants are persons of Spanish origin or descent according to the most recent federal decennial census.
(4) Notice of public hearing and city council approval. If the city council is required to approve a fill permit in accordance with this paragraph, after the neighborhood meeting, the director of water utilities shall schedule a public hearing on the application. The city secretary shall give notice of the public hearing in the official newspaper of the city at least 15 days before the date of the public hearing. The director shall also send written notice of the public hearing to the applicant, to all owners of real property within 500 feet from the boundary of the subject property, and to persons and organizations on the early notification list on file with the department of development services. Except as provided in this paragraph, the city council may only deny an application if the application does not meet the requirements of Sections 51A-5.105(f) or (g) or required state or federal permits have been denied.
(A) Variance requested. If a variance to one of the engineering criteria outlined in Subsection (g) is requested, the fill permit will require city council approval. The city council may grant a variance to the requirements of Subsection (g) if the variance will not violate any provision of federal or state law or endanger life or property.
(B) Property acquisition. If the department of development services or park and recreation recommend public acquisition of property due to its ecological, scenic, historic, or recreational value, they must make a written recommendation to city council, and the director of water utilities shall provide a report to the city council on the application regarding environmental impacts and public acquisition issues. Once the recommendation is made, the city council may vote to approve a resolution authorizing the acquisition of the property under the laws of eminent domain and deny the fill permit to preserve the status quo until the property is acquired.
(5) Director approval.
(A) After the applicant has satisfied all requirements of Subsections (f) and (g), and it is determined that city council approval is not necessary under Paragraph (4), the director of water utilities shall approve or deny the application for a fill permit. The director may only deny an application if:
(i) the application does not meet the requirements of Sections 51A-5.105(f) or (g); or
(ii) required state or federal permits have been denied.
(B) The director of water utilities may postpone the approval of a fill permit if:
(i) required state and federal permits have not been addressed or obtained; or
(ii) concerns from the department of development services or the park and recreation department have not been addressed.
(6) Zoning map revision. A letter of map revision must be obtained from FEMA, if applicable, before an FP prefix may be removed from the official zoning district map. A building permit may be issued for construction of underground utilities; however, no building permit for construction of a structure may be issued until a final letter of map revision (LOMR) is obtained. Upon approval and receipt of a letter of map revision, the director of water utilities shall notify the director of development services, who shall remove the FP designation for the subject area from the official zoning district map.
(f) Filling operations. If a fill permit or floodplain alteration permit is approved, the filling operations must comply with the following requirements:
(1) Any excavation required by the specifications of the approved application must be conducted before or at the same time as placing fill. Excavated areas are required to maintain a minimum depth of one foot at the deepest point.
(2) For fill permits, the entirety of the building pad site must be filled to an elevation of at least two feet above the design flood elevation. Habitable structures elevated on piers in floodplain areas are prohibited.
(3) For fill permits, tthe lowest floor of any structure must be constructed at least three feet above the design flood elevation.
(4) For fill permits within interior drainage (sump) areas, the building pad site must be filled to a minimum elevation of one foot above the design flood elevation. Habitable structures elevated on piers in floodplain areas are prohibited.
(5) Fill material must consist of natural material including but not limited to soil, rock, gravel, or broken concrete. Decomposable matter, including but not limited to lumber, sheetrock, trees, tires, refuse, or hazardous, toxic material, is prohibited as fill material. Fill must be compacted to 95 percent standard proctor density.
(6) Before construction, erosion and sediment control devices such as straw hay bales, silt fences, or similar items must be installed to eliminate any transportation of sediment downstream. The property owner is responsible for removal of any sediment deposited by runoff as a result of filling.
(7) If compliance with a Texas Pollutant Discharge Elimination System (TPDES) permit is required for construction activities, a copy of the Notice of Intent (NOI) or the individual TPDES permit must be submitted to the director of water utilities and the director of the office of environmental quality and sustainability before beginning fill operations. The Stormwater Pollution Prevention Plan required by TPDES must be implemented no later than two days prior to commencement of construction activities.
(8) Fill shall be placed no more than five feet above the design flood elevation, except where necessary to match the existing elevation of the adjacent property as determined by the director of water utilities. In determining when it is necessary to match the existing elevation, the director shall consider the effects on local drainage and storm water management, the access needs of the property, and other public health and safety concerns.
(9) A copy of the approved fill permit must be posted and maintained at the fill site for inspection purposes until fill operations have been completed.
(10) After filling operations have been completed, the applicant shall submit a certification to the director of water utilities that proper fill elevations in the form of signed and sealed as-built topographic survey, compaction requirements, and all other specifications of the approved application have been followed. In addition, a letter of map revision (LOMR) submittal to FEMA and approval by FEMA is required.
(11) Encroachment into the floodway is prohibited unless FEMA issues a conditional letter of map revision (CLOMR).
(g) Engineering requirements for filling.
(1) Except for detention basins and ponds, alterations of the FP area may not increase the water surface elevation of the design flood of the creek upstream, downstream, or through the project area. Detention basins and ponds may increase the water surface elevation of the design flood provided the increase is within the detention basin's or pond's boundaries as approved by the director of water utilities.
(2) Alterations of the FP area may not create or increase an erosive water velocity on or off-site. The mean velocity of stream flow at the downstream end of the site after fill may not exceed the mean velocity of the stream flow under existing conditions.
(3) The effects of the existing and proposed public and private improvements will be used in determining water surface elevations and velocities. Any alteration of the FP area necessary to obtain a removal of an FP prefix may not cause any additional expense in any current or projected public improvements.
(4) The FP area may be altered only to the extent permitted by equal conveyance reduction on both sides of the natural channel.
(5) FP areas governed by a city council-adopted management plan that contains valley storage regulations must comply with the valley storage regulations contained in the plan. For all other FP areas, a valley storage maintenance agreement on a form provided by the city and approved as to form by the city attorney's office is required, and the following requirements apply:
(A) no loss of valley storage is permitted along a stream in which the upstream drainage area is three square miles or more;
(B) valley storage losses along streams in which the upstream drainage area is between 100 acres and three square miles may not exceed 15 percent, as calculated on a site by site basis; and
(C) valley storage losses along streams in which the upstream drainage area is less than 100 acres are not limited.
(6) An environmental impact study and a complete stream rehabilitation program must be approved before relocation or alteration of the natural channel or alteration of an environmentally significant area, or area deemed to house threatened or endangered species. The net environmental impacts of the proposal may not be negative. The environmental impact study must contain the following items:
(A) A description of the existing conditions of the site, adjacent properties, upstream and downstream creek sections for approximately 1,000 feet (unless conditions require additional information in the opinion of the director of water utilities), and creek and overbank areas. The description of these conditions must include:
(i) the characterization of creek features such as bed quality and material, pool-riffle sequences, natural ground water, springs, seeps, magnitude and continuity of flow, water quality, bank quality and material, vegetative cover and patterns, bank erosion, topographic relief, disturbances to the natural character of the creek, animal and aquatic life, and the extent and character of wetland areas; and
(ii) soil types and land uses of the site and surrounding area.
(B) A description of the proposed project. This description must include:
(i) the intended ultimate use of the site, or if that is not known, a description of the interim site plan, including construction access;
(ii) reasons why the creek or floodplain alteration is necessary; and
(iii) a site plan showing the floodplain and construction access necessary to perform the work.
(C) A description of at least three possible ways of handling the creek and floodplain, including:
(i) an alternative that assumes the creek and floodplain are not changed;
(ii) the applicant's proposed action; and
(iii) alternatives proposed by the director of water utilities.
(D) An identification of the impacts created by each alternative, describing in detail all of the positive and negative impacts upon the existing conditions described in Subparagraph (A), that would be created by each alternative.
(E) A recommended course of action based upon evaluation of the alternatives.
(F) Proposed strategies to mitigate adverse impacts. Examples of strategies include tree wells, temporary construction and permanent erosion and sedimentation controls, vegetative buffers, and replacement planting.
(7) The toe of any fill slope must parallel the natural channel to prevent an unbalanced stream flow in the altered FP area.
(8) To insure maximum accessibility to the FP area for maintenance and other purposes and to lessen the probability of slope erosion during periods of high water, maximum slopes of the filled area may not exceed four to one for 50 percent of the length of the fill and six to one for the remaining length of the fill. The slope of any excavated area may not exceed four to one unless the excavation is in rock. Vertical walls, terracing, and other slope treatments may be used provided no unbalancing of stream flow results and the slope treatment is approved as a part of a landscaping plan for the property.
(9) The elevation of excavated areas in the FP area may not be lower than one-third of the depth of the natural channel, as measured from the adjacent bank, except for excavation of lakes. Excavation must be at least 50 feet from the bank of the natural channel, except as necessary to provide proper drainage.
(10) A landscape and erosion control plan must be submitted and approved. Landscaping must incorporate natural materials (such as earth and stone) on cut and filled slopes when possible. The definitions of Section 51A-10.101 apply to this subsection. Except as otherwise provided, the installation, removal, and maintenance requirements contained in the urban forest conservation regulations, Division 51A-10.130 of the Dallas Development Code, apply. Each soil resource and erosion control plan must comply with the following criteria:
(A) The size, type, and location of all proposed replacement trees to mitigate the loss of existing trees must be shown. The tree types must be selected in accordance with the provisions of Section 51A-10.134 and must be approved by the city arborist as suitable for use under local climate and soil conditions.
(B) The specific plant materials proposed to protect fill and excavated slopes must be indicated. Plant materials must be suitable for use under local climate and soil conditions. In general, hydroseeding or sodding native grasses is acceptable during the summer months (May 1st to August 30th). Winter rye or fescue grass may be planted during times other than the summer months as a temporary measure until such time as the permanent planting can be accomplished.
(C) The proposed methods of erosion and sedimentation control, such as hay bales and sedimentation basins, to be used during construction must be shown in detail.
(D) The fill case applicant, current owners, and subsequent owners must maintain and assure the survival of all planted material until the property is developed and a permanent maintenance plan of record is established. Maintenance responsibility must be reflected in the submitted plans or supporting documents.
(h) Term of permit validity and extension procedures.
(A) A fill permit or floodway alteration permit is valid for a five-year time period from the date of issuance. The fill permit or floodway alteration permit automatically terminates if the filling operations have not been completed within the five-year time period.
(B) New permit required upon expiration. When a fill permit terminates, the applicant must apply for a new permit before filling the property. The new application must comply with the floodplain regulations that are in effect at the time that the request is considered by the director.
(C) New permit required with site plan change. If the applicant wishes to make changes to a site plan that will change the hydraulic model or acreage of fill placed on the fill permit application after a fill permit has been approved, a new permit must be obtained.
(D) Presumption of completion. Filling operations are deemed completed when the applicant:
(i) submits a certification in the form of a signed and sealed topographic survey to the director of water utilities that proper fill elevations have been achieved and the specifications of the approved application have been followed;
(ii) submits compaction test results indicating the site was compacted to 95 percent standard proctor density; and
(a) For purposes of this section:
(1) NATURAL CHANNEL SETBACK LINE means that setback line described below located the farther beyond the crest:
(A) That line formed by the intersection of the surface of the land and the vertical plane located a horizontal distance of 20 feet beyond the crest.
(B) That line formed by the intersection of the surface of the land beyond the crest and a plane passing through the toe and extending upward and outward from the channel at the designated slope. For purposes of this paragraph, the designated slope is:
(i) four to one if the channel contains clay or shale soil; and
(ii) three to one in all other cases.
(2) CREST means that line at the top of the bank where the slope becomes less than four to one.
(3) TOE means that line at the bottom of the bank where the slope becomes less than four to one.
(b) Except as otherwise provided in Subsection (c), all development must be located behind the natural channel setback line.
(c) A structurally engineered retention system approved by the director may be substituted for the setback required in Subsection (b). (Ord. Nos. 19786; 24085; 25047; 28073; 32039)
(a) Definitions. In this section:
(1) CORRIDOR DEVELOPMENT CERTIFICATE (CDC) MANUAL means the manual by that title dated January 31, 1992, or its latest revision.
(2) FLOODPLAIN ALTERATION means any construction of buildings or other structures, mining, dredging, filling, grading, or excavation in the floodplain.
(3) TRINITY RIVER CORRIDOR means the portion of the floodplain of the West Fork, Elm Fork, and mainstem segments of the Trinity River floodplain within the Dallas city limits, as delineated on the latest CDC Regulatory Map.
(b) Certificate required. A person commits an offense if he makes any floodplain alteration within the Trinity River Corridor without first obtaining a corridor development certificate (CDC) from the director of water utilities. It is a defense to prosecution that an exemption or variance has been obtained in accordance with CDC criteria.
(c) Application. An application for a corridor development certificate must be filed with the director of water utilities on a form furnished by the department of water utilities.
(d) Review. The director of water utilities shall deny an application for a certificate unless it complies with the standards contained in the CDC Manual or unless an exemption from or a variance to those standards is obtained in accordance with Subsection (e).
(e) Exemptions and variances.
(1) Exemptions.
(A) An exemption from the requirements of this section may be obtained if the floodplain alteration involves the following activities:
(i) Ordinary maintenance of and repair to flood control structures.
(ii) The construction of outfall structures and associated intake structures if the outfall has been permitted under state or federal law.
(iii) Discharge of material for backfill or bedding for utility lines, provided there is no significant change in pre-existing bottom contours and excess materials are removed to an upland disposal area.
(iv) Bank stabilization.
(v) Any project listed in the U.S. Army Corps of Engineers March 1990 Reconnaissance Report, which is attached as Appendix A to the CDC Manual, or any project approved under the provisions of this division, provided the approval, permit, or authorization has not expired and no significant changes have occurred since the approval, permit, or authorization was issued.
(B) Application for an exemption must be made to the director of water utilities on a form provided by the department of water utilities.
(C) If the director of water utilities determines that an application for an exemption falls within one of the categories listed in Paragraph (1), the director shall issue a written exemption from the requirements of this section.
(2) Variances. If the director of water utilities determines that the application for a corridor development certificate does not comply with all of the standards contained in the CDC Manual, the applicant may apply for a variance to any standard contained in the manual. An application for a variance must be made to the director of water utilities, who shall schedule the application for consideration by the city council. (Ord. Nos. 21636; 24085; 27697; 30994; 32039)
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