(a)

Findings of fact.

(1)

The drainageways, creeks and flood hazard areas of the city are subject to periodic inundation which may result in the loss of life and property, health and safety hazards, disruption of commerce and governmental services and extraordinary public expenditures for flood protection and relief, all of which adversely affect the public health, safety and general welfare.

(2)

These flood losses could be created by the cumulative effect of obstructions in floodplains that increase flood heights and velocities and by placing structures and other improvements vulnerable to floods in flood hazard areas.

(3)

Watersheds within the city's jurisdiction are undergoing development or are facing development pressure, which, if not properly regulated, can adversely impact stormwater flows.

(4)

Watersheds within the city's jurisdiction, and especially those with abrupt topography, sparse vegetation, and thin and easily disturbed soil, are vulnerable to degradation resulting from development activities.

(5)

Streams and floodplain areas in the city are valuable resources to the citizens of the city in that they provide recreational opportunities, improve the aesthetics of the community, convey stormwater runoff and filter out water quality pollutants.

(b)

Statement of purpose. Stormwater management policies shall govern the planning, design, construction, operation and maintenance of storm drainage and erosion control facilities within the city. This article sets forth the minimum requirements necessary to provide and maintain a safe, efficient and effective drainage system within the city and to establish the various public and private responsibilities for the provision thereof. Further, it is the purpose of this article to:

(1)

Protect human life, health and property;

(2)

Minimize the expenditure of public money for building and maintaining flood control and storm drainage projects and cleaning sediment out of storm drains, streets, sidewalks and watercourses;

(3)

Minimize damage due to drainage and erosion to public facilities and utilities, such as water and gas mains, electric service, telephone and sewer lines, streets, bridges and drainageways;

(4)

Help maintain a stable tax base and preserve land values;

(5)

Insure that potential buyers are notified that property is in an area of special flood hazard;

(6)

Manage stormwater runoff, and the sediment load in that runoff, from points and surfaces within developments;

(7)

Establish a reasonable standard of design for development which prevents potential flood and erosion damage;

(8)

Reduce the pollutant loading to streams, ponds and other watercourses;

(9)

Minimize the need for rescue and relief efforts associated with flooding which are generally undertaken at the expense of the general public;

(10)

Minimize prolonged business interruptions.

(c)

Methods of reducing flood loss. In order to accomplish its purposes, this article uses the following methods:

(1)

Restrict or prohibit uses that are dangerous to health, safety or property in times of flood, or cause excessive increases in flood heights or velocities;

(2)

Require that uses vulnerable to floods, including facilities which serve such uses, be protected against flood damage at the time of initial construction;

(3)

Control the alteration of natural floodplains, stream channels, and natural protective barriers, which are involved in the accommodation of floodwaters;

(4)

Control filling, grading, dredging and other development which may increase flood damage;

(5)

Prevent or regulate the construction of flood barriers which will unnaturally divert floodwaters or which may increase flood hazards to other lands.

(d)

Scope of authority. Any person, firm, utility, corporation, business, or quasi-governmental or governmental entity proposing to develop land or improve property within the jurisdiction of the city is subject to the provisions of this article. This article also applies to individual building structures, subdivisions, excavation and fill operations and similar activities.

(e)

Lands to which this article applies.

(1)

This article shall apply to all areas of land meeting each of the following conditions:

(A)

Located within the incorporated limits and extraterritorial jurisdiction of the city.

(B)

Development or redevelopment of one acre or more.

(C)

Development or redevelopment will result in an increase in impervious area of five percent more than existing conditions.

(2)

The erosion control provisions of this article do not apply to land under active agricultural use. As soon as construction or modification to the lands under active agricultural use is proposed so that the use of land will change from agriculture to any other use, then the erosion control provisions of this article shall be applicable to the once-exempted land.

(f)

City stormwater design manual. This article is designed to require an accompanying stormwater design manual, which describes in detail the technical procedures to be used to comply with the provisions contained in this article. The criteria specified in the city stormwater design manual shall become part of the official stormwater management plan for streams, channels, NRCS lakes and pipe drainage systems in the city. Although the intention of the manual is to establish uniform design practices, it neither replaces the need for engineering judgment nor precludes the use of information not presented. Other accepted engineering procedures may be used to conduct hydrologic and hydraulic studies if approved by the city engineer.

(g)

Basis for establishing the areas of special flood hazard. The areas of special flood hazard, identified by the Federal Emergency Management Agency in a scientific and engineering report entitled "Flood Insurance Study, Tom Green County, Texas and Incorporated Areas," with the accompanying flood insurance rate maps dated March 2, 1994 and any revisions thereto, are hereby adopted by reference and declared to be a part of this article.

(h)

Abrogation and greater restrictions. This article is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions. However, where this article and another municipal ordinance, easement, covenant or deed restriction conflict or overlap, whichever ordinance imposes the more stringent restrictions shall prevail.

(i)

Interpretation. In the interpretation and application of this article, all provisions shall be:

(1)

Considered as minimum requirements;

(2)

Liberally construed in favor of the governing body; and

(3)

Deemed neither to limit nor repeal any other powers granted under state or federal statutes.

(j)

Warning and disclaimer of liability. The degrees of flood, storm drainage, and erosion protection required by this article are considered reasonable for regulatory purposes and are based on scientific and engineering considerations. Larger floods can and will occur. Flood heights may be increased by man-made or natural causes. This article does not imply that land outside the areas of flood hazard or uses permitted within such areas will be free from flooding or flood damages. In addition, this article does not imply that erosion controls will survive inundation by runoff from storms greater than the design flood for erosion controls. This article shall not create liability on the part of the city, or any officer or employee thereof, for any flood damages that result from reliance on this article or any administrative decision lawfully made thereunder.

(k)

Severability. If any section, paragraph, clause, phrase, or provision of this article shall be judged invalid or held unconstitutional, the same shall not affect the validity of this article as a whole or any part or provision thereof, other than the part so decided to be invalid or unconstitutional; nor shall such unconstitutionality or invalidity have an effect on any other ordinances or provisions of ordinances of the city.

(l)

Regulatory permits. It shall be the developer's responsibility to secure all regulatory permits associated with development of drainage improvements. These include, but are not limited to, U.S. Corps of Engineers 404 permits, state commission on environmental quality section 401 permits, Federal Emergency Management Agency floodplain revision permits, U.S. Environmental Protection Agency National Pollutant Discharge Elimination System permits, and any city permits.

(m)

Variances. Requests for variances and deviations from this article are to be submitted to the city, and will be received and approved or disapproved by the city in accordance with provisions of this article.

(n)

Maintenance of drainage improvements. Public drainage improvements dedicated (in the right-of-way or by fee simple dedication to the public) and accepted by the city will be maintained and operated by the city. A maintenance agreement between the developer and the city is required and will be recorded for drainage systems not dedicated to and/or accepted by the city.

(o)

Parks and open space. By integrating parks and open space into stormwater management, it is possible to maintain the natural flood storage capacity of drainageways while providing community resources for the benefit of the public. The city encourages the creation and use of parks and open space in managing stormwater runoff.

(1996 Code, sec. 12.401; Ordinance adopted 11-16-10)

Unless specifically defined below, words or phrases used in this article shall be interpreted to give them the meaning they have in common usage and to give this article its most reasonable application.

Two-year storm event. The flood having a 50 percent chance of being equaled or exceeded in any given year. This is also the two-year mean recurrence interval storm event.

100-year storm event. The flood having a one percent chance of being equaled or exceeded in any given year. This is also the 100-year mean recurrence interval storm event (see also "base flood" and "design flood").

Appeal. A request for review of the floodplain administrator's interpretation of any provision of this article or a request for a variance.

Applicant. Any firm, entity, partnership, company, public utility, company or individuals who plan to clear, grub, fill, excavate, grade or otherwise remove the vegetative cover of land, or who plan to either subdivide land and install the appropriate infrastructure or renovate existing structures shall become applicants for a development permit upon submission of the appropriate application materials.

Area of shallow flooding. A designated AO or AH zone on the flood insurance rate map (FIRM) with a one percent or greater annual chance of flooding to an average depth of one to three feet, where a clearly defined channel does not exist, and the path of flooding is unpredictable and indeterminate. Such flooding is characterized by ponding or sheet flow.

Area of special flood hazard. The land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. This area may be designated as zone A on the flood hazard boundary map (FHBM) or zone X. After detailed rate-making has been completed in preparation for publication of the FIRM, zone A usually is refined into zone A, AE, AH, AO, A1-99, VO, V1-30, VE, or V.

Base flood. The flood having a one percent chance of being equaled or exceeded in any given year, based upon the FEMA guidelines and as shown in the current effective flood insurance study (FIS). This 100-year mean recurrence interval storm event is based on existing watershed conditions.

Base flood elevation. The water surface elevation resulting from the base flood.

Basement. Any area of the building having its lowest floor subgrade (below ground level) on all sides.

Best management practices (BMPs). A wide range of management procedures, schedules of activities, and prohibitions on practices which have been demonstrated to effectively control the quality and/or quantity of stormwater runoff and which are compatible with the planned land use.

Builder. A person, partnership or corporation engaged in clearing, grubbing, filling, excavating, grading, constructing a pad, installing service utility lines and/or constructing or placing a building(s) or other structure(s) on a lot or other type of tract of land that is owned by the person, partnership or corporation, and that will not be further subdivided in other lots.

Channel. A natural or artificial stream that conveys water. Channels are often further classified by their size and purpose. For example, there are primary and secondary channels based on size, but diversions, waterways, and chutes are also channels.

Channel improvement. The improvement of the flow characteristics of a channel by clearing, excavating, realigning, lining or other means in order to increase its capacity. The term is sometimes used to mean channel stabilization.

Channel stabilization. Erosion prevention and stabilization of velocity distribution in a channel using jetties, drops, revetments, vegetation and other measures.

City jurisdiction. All land located within the corporate limits of the city or its extraterritorial jurisdiction.

City-maintained land. Any land in actual ownership of the city; it does not include any type of easements that remain in private ownership.

Conduit. Any open or closed device for conveying flowing water.

Culvert. A large pipe or other conduit through which a stormwater flows under a road or street.

Curb. A vertical or sloping rim along the edge of a roadway, normally constructed integrally with the gutter, which strengthens and protects the pavement edge and clearly defines the pavement edge to vehicle operators.

Curb inlet. A vertical opening in a curb through which the gutter flow passes. The gutter may be undepressed or depressed in the area of the curb opening.

Dam. A barrier constructed across a watercourse for the purposes of:

(1)

Creating a reservoir;

(2)

Diverting water from a conduit or channel.

Degradation. The progressive general lowering of a stream channel by erosion.

Design flood. When in the context of floods, floodplains or flood hazards, the design flood is that level of flood upon which a structure impacted by that flood is designed to withstand. This is assumed to be the flood with a one percent chance of being equaled or exceeded in any given year, based upon fully developed watershed conditions, unless specifically stated otherwise.

Design storm. The storm or flood which is used as the basis for design, i.e., against which the structure is designed to provide a stated degree of protection or other specified result.

Detention. The storage of storm runoff for a controlled release during or immediately following the design storm.

(1)

Off-site detention. A detention pond located outside the boundary of the area it serves.

(2)

On-site detention. A detention pond which is located within and serves only a specific site or subdivision.

(3)

On-stream detention. Detention facilities provided to control excess runoff based on a watershed-wide hydrologic analysis.

Detention basin. A dry basin or depression constructed for the purpose of temporarily storing stormwater runoff and discharging all of that water over time at a rate reduced from the rate that would have otherwise occurred.

Developer. A person, partnership or corporation who owns a tract of land and who is engaged in clearing, grubbing, filling, mining, excavating, grading, installing streets and utilities to be dedicated to or accepted by the city and/or otherwise preparing that tract of land for the eventual division of the tract into one or more lots on which building(s) or other structure(s) will be constructed or placed.

Development. Any man-made change to improved or unimproved real estate, including, but not limited to, adding buildings or other structures, mining, dredging, filling, grading, paving, excavation, drilling operations, clearing, or removing vegetative cover.

Discharge hydraulics. The rate of fluid flow, expressed as the volume of fluid passing a point per unit time, commonly expressed as cubic feet per second.

Disturbance. Any operation or activity, such as clearing, grubbing, filling, excavating, mining, cutting, grading, or removing channel linings, which results in the removal or destruction of the protective cover of soil, including vegetative cover, channel linings, retaining walls, and slope protection.

Disturbed areas. Any area or tract of land in which a disturbance is occurring or has occurred but that has not been stabilized.

Downstream impact area. Area within which calculations are to be made to determine downstream adequacy, defined as the area between the proposed development and the FEMA-designated stream or streams receiving stormwater runoff from the proposed development or to a designated structure approved by the city engineer, whichever is less.

Elevated building. A nonbasement building:(1) built, in the case of a building in zones A1-30, AE, A99, AO, AH, B, C, X, and D, to have the top of the elevated floor, or in the case of a building in zone V1-30, VE, or V, to have the bottom of the lowest horizontal structural member of the elevated floor, elevated above the ground level by means of pilings, columns (posts and piers), or shear walls parallel to the flow of the water; and (2) adequately anchored so as not to impair the structural integrity of the building during a flood of up to the magnitude of the base flood. In the case of zones A1-30, AE, A, A99, AO, AH, B, C, X and D, "elevated building" also includes a building elevated by means of fill or solid foundation perimeter walls with openings sufficient to facilitate the unimpeded movement of floodwaters. In the case of zone V1-30, VE, or V, "elevated building" also includes a building otherwise meeting the definition of "elevated building," even though the lower area is enclosed by means of breakaway walls, if the breakaway walls meet the standards of section 60.3(e)(5) of the National Flood Insurance Program regulations.

Erosion. The wearing away of land by action of wind and water.

Exceedance probability. The statistical probability that an event will equal or exceed a specific magnitude.

Existing construction. For the purposes of determining flood insurance rates, structures for which the "start of construction" commenced before the effective date of the FIRM for the community, July 27, 1976. "Existing construction" may also be referred to as "existing structures."

Existing manufactured home park or subdivision. A manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) was completed before the effective date, July 27, 1976, that floodplain management regulations were adopted by the community.

Expansion to an existing manufactured home park or subdivision. The preparation of additional sites by the construction of facilities for servicing lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) in an existing manufactured home park or subdivision beyond those that had been completed prior to the effective date, July 27, 1976, that floodplain management regulations were adopted by the community.

Federal Emergency Management Agency (FEMA). The federal agency which administers the National Flood Insurance Program.

Finished floor elevation. The lowest floor of the lowest enclosed area (including basement). An unfinished or flood-resistant enclosure usable 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, provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirement of section 60.3 of the National Flood Insurance Program regulations.

Flexible pipe. Any corrugated metal pipe, pipe-arch, sectional plate pipe, sectional plate pipe-arch or plastic (polyethylene) pipe.

Flood or flooding. A general and temporary condition of partial or complete inundation of normally dry land areas from either the overflow of inland waters and/or the unusual and rapid accumulation or runoff of surface waters from any source.

Flood insurance rate map (FIRM). The official map on which the Federal Emergency Management Agency has delineated both the areas of special flood hazard and the risk premium zones applicable to the community.

Flood insurance study (FIS). The official report provided in which the Federal Emergency Management Agency has provided flood profiles, as well as the flood boundary/floodway map and the water surface elevation of the base flood.

Flood protection system. Those physical structural works for which funds have been authorized, appropriated and expended and which have been constructed specifically to modify flooding in order to reduce the extent of the areas within a community subject to a "special flood hazard" and the extent of the depths of associated flooding. Such a system typically includes dams, reservoirs, channels, levees or dikes. These specialized flood-modifying works are those constructed in conformance with sound engineering standards.

Floodplain or area of special flood hazard. Any land area susceptible to being inundated by floodwaters from a 100-year or larger storm event.

Floodplain development permit. All developers, owners or builders shall obtain a floodplain development permit before beginning any projects in floodplain areas, including but not limited to: constructing new buildings and infrastructure, filling land, altering waterways, substantially improving existing structures located in flood hazard areas or channelizing, impounding, realigning, deepening or other altering of a natural drainageway. Construction or renovation projects cannot begin until the city issues the floodplain development permit. Building permits cannot be issued before a floodplain development permit is issued.

Floodplain management. The operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to emergency preparedness plans, flood control works, and floodplain management regulations.

Floodplain management regulations. Zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as a floodplain ordinance, grading ordinance, and erosion control ordinance) and other applications of police power. The term describes such state or local regulations, in any combination thereof, which provide standards for the purpose of flood damage prevention and reduction.

Floodproofing. Any combination of structural and non-structural additions, changes or adjustments to structures which reduce or eliminate flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents.

Floodway (regulatory floodway). The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.

Flume. Any open conduit on a prepared grade, trestle or bridge.

Freeboard. The distance between the normal operating level and the top of the side of an open conduit left to allow for wave action, floating debris, or any other condition or emergency without overtopping the structure.

Frequency (of storms, floods). Average recurrence interval of a given flood event over long periods of time. Mathematically, frequency is the reciprocal of the exceedance probability.

Fully developed conditions. The level of development anticipated when all of the land within a watershed is developed to the maximum extent allowable, typically determined by comparing existing and projected land uses on vacant and nonconforming properties based upon existing zoning or the latest land use plan, whichever is more intense.

Functionally dependent use. A use which cannot perform its intended purpose unless it is located or carried out in proximity to water.

Grade.

(1)

The inclination or slope of a channel, canal, conduit, etc., or natural ground surface, usually expressed in terms of the percentage of number of units of vertical rise (or fall) per unit of horizontal distance.

(2)

The elevation of the bottom of a conduit, canal, culvert, sewer, etc.

(3)

The finished surface of a canal bed, road bed, top of an embankment, or bottom of excavation.

Gutter. A generally shallow waterway adjacent to a curb, used or suitable for drainage of water.

Highest adjacent grade. The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.

Historic structure. Any structure that is:

(1)

Listed individually in the National Register of Historic Places (a listing maintained by the Department of the Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;

(2)

Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary of the Interior to qualify as a registered historic district;

(3)

Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or

(4)

Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:

(A)

By an approved state program as determined by the Secretary of the Interior; or

(B)

Directly by the Secretary of the Interior in states without approved programs.

Hydraulic grade line. A line representing the pressure head available at any given point within the system.

Hydraulic gradient. A hydraulic profile of the piezometric level of the water, representing the sum of the depth of flow and the pressure head. In open channel flow it is the water surface.

Hydraulics. A branch of science that deals with practical applications of the mechanics of water movement.

Hydrology. The science that deals with the processes governing the depletion and replenishment of the water resources of the land areas of the earth.

Impervious. A term applied to a material through which water cannot pass, or through which water passes with great difficulty.

Inlet.

(1)

An opening into a storm sewer system for the entrance of surface storm runoff, more completely described as a storm sewer inlet;

(2)

A structure at the diversion end of a conduit;

(3)

The upstream connection between the surface of the ground and a drain or sewer, for the admission of surface or storm water.

Levee. A man-made structure, usually an earthen embankment, designed and constructed in accordance with sound engineering practices to contain, control or divert the flow of water so as to provide protection from temporary flooding.

Lowest floor. The lowest floor of the lowest enclosed area (including basement). An unfinished or-flood resistant enclosure, usable 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, provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirement of section 60.3 of the National Flood Insurance Program regulations.

Major streams. Streams with FEMA-defined floodplains and all zone A (approximate) areas based on the current FEMA flood insurance study.

Manufactured home. A structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when connected to the required utilities. For floodplain management purposes, the term "manufactured home" also includes park trailers, travel trailers and other similar vehicles placed on a site for greater than 180 consecutive days. For insurance purposes, the term "manufactured home" does not include park trailers, travel trailers and other similar vehicles.

Manufactured home park or subdivision. A parcel or contiguous parcels of land divided into two or more manufactured home lots for rent or sale.

Mean sea level (MSL). For the purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum (NGVD) of 1929 or other datum to which base flood elevations shown on a community's flood insurance rate map are referenced.

New construction. Structures for which the "start of construction" commenced on or after July 27, 1976, defined for the purpose of determining FEMA flood protection rates.

New manufactured home park or subdivision. A manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed (including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads) is to be completed on or after the effective date, July 27, 1976, that floodplain management regulations were adopted by the community.

Outfall. The point where water flows from a stream, river, lake or artificial drain.

Peak flow or discharge. The maximum instantaneous flow from a given storm condition at a specific location.

Post-development. The condition of the given site and drainage area after the anticipated development has taken place.

Precipitation. Any moisture that falls from the atmosphere, including snow, sleet, rain and hail.

Pre-development. The condition of the given site and drainage area prior to development.

Principal spillway. Generally, is constructed of permanent material and designed to regulate the normal water level, provide flood protection and reduce the frequency of operation of the emergency spillway.

Probable maximum flood (PMF). The flood that may be expected from the most severe meteorological and hydrologic conditions that are reasonably possible in the region.

Probable maximum precipitation (PMP). The critical depth-duration-area rainfall relationship for a given area during a storm containing the most critical meteorological conditions considered probable of occurring.

Problematic maximum flood. The flood that may be expected from the most severe meteorological and hydrologic conditions that are reasonably possible in the region.

Public erosion nuisance. A situation in which erosion of or sediment from one location is causing a bothersome or unsightly condition on another property owned by a different individual or entity. A bothersome or unsightly condition or burden includes silt, mud or similar debris originating from one property but being deposited onto a second off-site property in which that off-site owner may have to remove or clean up the deposit due to liability, statutory, aesthetic, drainage or property damage concerns. The adversely affected off-site property owner could be a private citizen, corporation, government or other entity.

Rainfall duration. The length of time over which a single rainfall event occurs.

Rainfall frequency. The average recurrence interval of rainfall events, averaged over long periods of time.

Rainfall intensity. The rate of accumulation of rainfall, usually in inches or millimeters per hour.

Record drawing. A set of engineering or site drawings that delineate the specific permitted stormwater management facility as actually constructed.

Recreational vehicle. A vehicle which is:

(1)

Built on a single chassis;

(2)

400 square feet or less when measured at the largest horizontal projections;

(3)

Designed to be self propelled or permanently towable by a light duty truck; and

(4)

Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.

Recurrence interval. The average interval of time within which a given event is statistically predicted to be equaled or exceeded once. For an annual series (as opposed to a partial duration series), it is the probability of occurrence interval. Thus a flood having a recurrence interval of 100 years has a one percent probability of being equaled or exceeded.

Regulatory floodway. The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the "base flood," as determined by the Federal Emergency Management Agency, without cumulatively increasing the water surface elevation more than a designated height. This floodway is used by FEMA to determine compliance with its regulations.

Retention basin. A pond or other water body which has been designed to have both a conservation pool for holding some water indefinitely and a flood storage pool for storing stormwater runoff on a temporary basis for the purpose of reducing the peak discharge from the basin for improving the water quality of the stream flow.

ROW (right-of-way). A strip of land dedicated for public streets and/or related facilities, including utilities, drainage systems and other transportation uses.

ROW width. The shortest horizontal distance between the lines which delineate the limits of right-of-way of a street.

Runoff. That part of the precipitation that exceeds abstractions and reaches a stream or storm drain.

Sheet flow. Water, usually storm runoff, flowing in a thin layer over the ground surface. Synonymous with "overland flow."

Standard project flood. A flood that has a magnitude of approximately one-half of the probable maximum flood, as determined on a case-by-case basis using accepted engineering methods.

Start of construction. For a structure, "start of construction" includes substantial improvement and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, placement or other improvement was within 180 days of the permit date. The actual start means either the first placement of permanent construction of a structure on a site, such as the pouring of a slab or footings, the installation of piles, the construction of columns or any work beyond the stage of excavation, or the placement of a manufactured home on a foundation. Permanent construction of a structure does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure.

Storm frequency. An expression or measure of how often a hydrologic event of given size or magnitude should, on an average, be equaled or exceeded.

Stormwater design manual. The design manual used to establish standard principles and practices for the design and construction of storm drainage facilities within the city and within its extraterritorial jurisdiction.

Stormwater management. The control of storm runoff by means of land use restrictions, detention storage, erosion control, and/or drainage systems.

Structure. A walled and roofed building, a manufactured home, a substation or a gas or liquid storage tank that is principally above ground. When used in the context of stormwater, the term means a drainage improvement, such as dams, levees, bridges, culverts, channels, headwalls, flumes, etc.

Substantial improvement. Any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure before "start of construction" of the improvement. This includes structures which have incurred "substantial damage," regardless of the actual repair work performed. The term does not, however, include either:

(1)

Any project for improvement of a structure to correct existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary conditions; or

(2)

Any alteration of a "historic structure," provided that the alteration will not preclude the structure's continued designation as a "historic structure."

Temporary erosion protection. The stabilization of erosive or sediment-producing areas for a specific time period, usually during a construction job.

Ultimate development. The condition of the watershed after the entire watershed has undergone development.

Variance. A grant of relief to a person from the minimum standard requirements of this article, but comply[ing] with section 60.6 of the National Flood Insurance Program regulations, when specific enforcement would result in unnecessary hardship. A variance, therefore, permits construction or development in a manner otherwise prohibited by this article. Variance requirements shall comply with any other city ordinances.

Violation. The failure of a structure or other development to be fully compliant with this article. A structure or other development without the elevation certificate, other certifications, other evidence of compliance required in the National Flood Insurance Program regulations, or other evidence as required by the city engineer is presumed to be in violation until such time as that documentation is provided.

Water surface elevation. The height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929 (or other datum, where specified), of floods of various magnitudes and frequencies in the floodplains of riverine areas.

Watershed. The area contributing storm runoff to a stream or drainage system. Other terms are "drainage area," "drainage basin" and "catchment area."

(1996 Code, sec. 12.402; Ordinance adopted 11-16-10)

(a)

Duties of city officials. The city engineer, or his designated agent, is hereby appointed the floodplain administrator to administer and implement the provisions of this section and other appropriate sections of 44 CFR (National Flood Insurance Program regulations) pertaining to floodplain management. The duties of the city engineer shall include, but not be limited to:

(1)

Review and approve or disapprove all floodplain development permits to determine that the permit requirements of this article have been met;

(2)

Maintain for public inspection all records pertaining to the provisions of this article, including floodproofing certifications;

(3)

Notify, in riverine situations, adjacent communities and the state commission on environmental quality prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Emergency Management Agency;

(4)

Make interpretations, where needed, as to the exact location of the boundaries of the areas of special flood hazard (for example, where there appears to be a conflict between a mapped boundary and actual field conditions);

(5)

Inspect sites to determine compliance with the erosion control guidelines;

(6)

Review permit applications to determine whether proposed building sites, including the placement of manufactured homes will be reasonably safe from flooding;

(7)

Review permits for proposed development to see what permits have been obtained from those federal, state, or local governmental agencies (including section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C 1334) from which prior approval is required;

(8)

Assure that the flood-carrying capacity within the altered or relocated portion of any watercourse is maintained;

(9)

When base flood elevation data has not been provided in accordance with this article, the city engineer shall obtain, review and reasonably utilize any base flood elevation data and floodway data available from a federal, state, or other source, in order to administer the provisions of this article;

(10)

When a regulatory floodway has not been designated, the city engineer must require that no new construction, substantial improvements, or other developments (including fill) shall be permitted within zones A1-30 and AE on the community's FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community;

(11)

Under the provisions of 44 CFR chapter 1, section 65.12, of the National Flood Insurance Program regulations, the city engineer may approve certain development in zones A1-30, AE, and AH on the community's FIRM which increases the water surface elevation of the base flood by more than one foot, provided that an application and approval for a conditional FIRM revision is made and received from FEMA.

(b)

Responsibilities of property owners.

(1)

The owner or developer of a property to be developed shall be responsible for managing all storm drainage flowing through or abutting such property. This responsibility also includes drainage directed to that property by future development as well as the drainage naturally flowing through the property by reason of topography. The owner, builder or developer of a property shall be responsible for any concentrated flows, silt, and soils that discharge from his property. It is the intent of this article that provisions be made for managing stormwater discharges and preventing erosion and sedimentation problems.

(2)

Where the improvement or construction of a storm drainage facility is required along a property line common to two or more owners, the owner hereafter proposing the development of the property shall be responsible for obtaining the necessary city permits, making the improvements required by this article and the stormwater design manual at the time of development and acquiring or dedicating the necessary rights-of-way or easements to accommodate the improvements.

(3)

Where an applicant proposes development or use of only a portion of the property, provisions for storm drainage and erosion control shall only be required in that portion of the property proposed for immediate development, except as construction or improvements of a drainage facility or erosion controls outside that designated portion of the property are deemed essential to the development of that designated portion.

(4)

The owner or developer of a property must insure that all necessary local, state and federal permits have been obtained.

(c)

Plat review and approval process.

(1)

The city has several approval processes and permits in place which relate to stormwater drainage and floodplains. These processes and permits include but are not limited to:

(A)

Platting process. In accordance with the city's subdivision regulations, a construction plan and profile sheets for all public improvements, including drainage facilities, shall be submitted as part of the final platting process. Requirements for preliminary and final plat submission are outlined in the stormwater design manual of the city.

(B)

Dedication of drainage easement. Public drainage systems designed to convey the design storm runoff shall be contained within a drainage easement or a floodplain/floodway easement or property dedicated to the public, except for allowances specifically identified in this article and the stormwater design manual.

(C)

Floodplain development permit (areas of special flood hazard). All developers, owners or builders shall obtain a floodplain development permit before beginning any projects in floodplain areas, including but not limited to: constructing new buildings and infrastructure, filling land, altering waterways, substantially improving existing structures located in flood hazard areas or channelizing, impounding, realigning, deepening or other altering of a natural drainageway. Construction or renovation projects cannot begin until the city issues the floodplain development permit. Building permits cannot be issued before a floodplain development permit is issued.

(2)

Approval or denial of a floodplain development permit by the city engineer shall be based on the provisions of this article and the following relevant factors:

(A)

The danger to life and property due to flooding or erosion damage;

(B)

The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;

(C)

The danger that materials may be swept onto other lands to the injury of others;

(D)

The compatibility of the proposed use with existing and anticipated development;

(E)

The safety of access to the property in times of flood for ordinary and emergency vehicles;

(F)

The cost of providing governmental services during and after flood conditions, including maintenance and repair of streets and bridges, and public utilities and facilities such as sewer, gas, electrical, and water systems;

(G)

The expected heights, velocity, duration, rate of rise and sediment transportation of the floodwaters and the effects of wave action, if applicable, expected at the site;

(H)

The necessity to the facility of a waterfront location, where applicable;

(I)

The availability of an alternative location, not subject to flooding or erosion damage, for the proposed use;

(J)

The relationship of the proposed use to the comprehensive plan for that area.

(d)

Deviations from permit terms.

(1)

Permits may be revoked by the city engineer if, upon periodic inspection, it is determined that the work is not progressing in accordance with specifications of the approved plan and permit or if it is determined that erosion from a building or construction site is not being controlled in a satisfactory manner.

(2)

Field changes to drainage system plans can be made upon the approval of the city engineer. Record drawings of the drainage system shall be submitted to the city engineer at the completion of the project.

(e)

Plan requirements.

(1)

Application materials and plan requirements for drainage systems or floodplain alterations are listed below. All engineering plans for storm drainage and floodplain alteration projects shall be sealed by a professional engineer who is licensed in the state and experienced in civil engineering work. The total cost for preparing the engineering plans and implementing the plans shall be borne by the applicant.

(A)

Storm drainage plans. As part of the development process, storm drainage reports and plans shall be prepared. These reports and plans shall include drainage facilities for both off-site and on-site drainage, so that the proper transition between the two can be maintained. Criteria for on-site development shall also apply to off-site improvements. The construction of all improvements shall be in accordance with the current specifications and regulations adopted by the city. Storm drainage plans shall be prepared in accordance with section 2.13 of the stormwater design manual.

(B)

Application materials for floodplain development permits. Owners or builders who are planning to renovate existing structures or construct new structures shall apply for a building permit in accordance with this article. If it is determined during the permit review that the proposed project is located in an area of special flood hazard, then the building permit applicant shall also be required to apply for a floodplain development permit through the city engineer and submit for review copies of the appropriate design materials.

(2)

For projects involving an existing structure located in areas of special flood hazard:

(A)

Plan and profile plans to scale, showing all existing and proposed topography, including lowest finished floor elevations (including basements) and all relevant hydrologic and hydraulic information. See section 2.13 of the stormwater design manual for preliminary and final plan submittal requirements.

(B)

A cost estimate of the proposed improvements or a copy of the contract amount for making the improvements, if city cost participation is requested.

(C)

Plans, sealed by a licensed professional engineer in the state, of any proposed flood prevention techniques and elevation in relation to mean sea level for structures.

(D)

A certificate from a licensed professional engineer or architect, stating that the proposed flood prevention techniques used on structures meet the requirements of this article.

(3)

For all subdivisions and new construction in a special flood hazard area:

(A)

An engineering report with the following recommended format, as applicable:

(i)

Project description: Description of the hydrologic and hydraulic analyses used, including the method or source used to determine historic rainfall and stream data, soils reports used to determine erosive velocity values and discharges and water surface elevations for both the 2-year and the 100-year storm event.

(ii)

Vicinity map.

(iii)

Table of values for existing and proposed water surface elevations and velocities.

(iv)

Documentation that the principle of equal conveyance has been achieved. Engineering calculations for existing and proposed conditions for both the 2-year and 100-year storm event discharges.

(B)

Engineering drawings consisting of the following recommended elements, as applicable:

(i)

Water surface profile, including channel flow line, existing and proposed water surface elevations and location and number designation of cross-sections.

(ii)

Plans as specified in section 2.13 of the stormwater design manual for preliminary and final plan submittals.

(1996 Code, sec. 12.403; Ordinance adopted 11-16-10)

(a)

Generally. It is the policy of the city to require a drainage study on industrial, commercial, or multiple lot residential developments to be developed in the city, including the ETJ. If a study was not completed on an area that was previously platted, a final drainage study will be required at the time of permitting for improvements, unless the city engineer waives the requirement.

(b)

Preliminary drainage study.

(1)

When required. It is the policy of the city to discuss and conceptually resolve drainage issues of a development at the preliminary plat stage. The applicant shall submit a preliminary drainage study prior to the submittal of any preliminary plat of a proposed development. A preliminary drainage study may also be required by the city when reviewing the merits of a change in zoning, especially when the proposed use is more intense than the current land use. Approval of the preliminary plat or zoning change may be contingent on the acceptability of the solutions proposed by the preliminary drainage study.

(2)

Qualification to prepare the study. The preliminary drainage study shall be prepared by a professional engineer licensed in the state, experienced in civil engineering, and having a thorough knowledge of the study of drainage issues. The preliminary drainage study shall be signed, sealed, and dated by the engineer responsible for the preparation of the study.

(3)

Requirements. The requirements for a preliminary drainage study shall be established and periodically updated by the city engineer. These requirements are found in the stormwater design manual.

(4)

Exemptions. The city engineer may waive the requirement of the preliminary drainage study or may limit certain requirements where the city engineer determines that such requirements are not necessary for a proper review of the development.

(c)

Final drainage study.

(1)

When required. It is the policy of the city to resolve drainage issues of a development at the final plat stage. The applicant shall be required to submit a final drainage study with the submittal of the final plat, or construction permitting phase, if a final drainage study has not been previously completed for the proposed development or conditions have been modified. Approval of the above-mentioned plats or construction shall be contingent on the acceptability of the solutions proposed by the final drainage study.

(2)

Qualifications to prepare the study. The final drainage study shall be prepared by a professional engineer licensed in the state, experienced in civil engineering, and having a thorough knowledge of the study of drainage issues. The final drainage study shall be signed, sealed, and dated by the engineer responsible for the preparation of the study.

(3)

Requirements. The requirements for a final drainage study shall be established and periodically updated by the city engineer. These requirements are found in the stormwater design manual.

(4)

Exemptions. The city engineer may waive the requirement of the final drainage study or may limit certain requirements where the city engineer determines that such requirements are not necessary for a proper review of the development.

(d)

Drainage study submittals.

(1)

A review process has been established by the city for development activities related to stormwater runoff through natural or man-made facilities. As part of the review process, a preliminary drainage study containing the conceptual layout of the proposed storm drainage system shall be submitted as part of the preliminary platting process in accordance with this article.

(2)

A final drainage study shall be submitted as part of the final platting process. The final drainage study shall include the appropriate computation sheets as required in the stormwater design manual. Final drainage studies of all proposed improvements or land developments shall clearly identify the on-site and off-site drainage system improvements required to satisfy this article, and identify the upstream and downstream limits to which the improvements or development comply with the design criteria in this article and the stormwater design manual.

(1996 Code, sec. 12.404; Ordinance adopted 11-16-10)

(a)

Generally.

(1)

The selection of an appropriate method for calculating runoff depends upon the size of the drainage area contributing runoff at a most downstream point of a project. The rational method is acceptable for situations in which the drainage area is generally less than 200 acres. A unit hydrograph method is required for situations with larger drainage areas. These methods are described in chapters 4 and 5 the stormwater design manual.

(2)

Runoff calculations for property within the city limits and ETJ of the city shall be completed that assess the upstream drainage areas that flow onto or through the proposed development for fully developed watershed conditions in accordance with the city's latest land use projections. Portions of the watershed which lie outside the city limits and ETJ of the city shall be analyzed and accommodated based on existing land use conditions.

(b)

Downstream impact assessment. The downstream impacts of proposed development must be carefully evaluated to show that design criteria established in this article and the stormwater design manual are met. The purpose of the downstream assessment is to protect downstream properties from increased flooding, to protect downstream channels from increased erosion potential due to upstream development, and to protect public health and safety. The assessment shall extend from each outfall of a proposed development to a major stream (FEMA-defined floodplain), to a stormwater facility identified by the city as having fully developed flow capacity or to a point designated by the city engineer, whichever is the nearest point downstream. Runoff computations shall be based upon fully developed watershed conditions in accordance with the city's latest land use projections. Portions of the watershed which lie within the city limits and ETJ of the city shall be analyzed and accommodated as if fully developed. Portions of the watershed which lie outside the city's limits and ETJ shall be analyzed for existing conditions.

(c)

Limitation of runoff. Calculations using the following runoff limitation options shall be performed for the proposed development to demonstrate downstream adequacy in accordance with the design criteria in this article and the stormwater design manual:

(1)

If the necessary future capacities of the affected drainage systems within the downstream impact area are shown to adequately convey the fully developed two-year and 100-year design flows from the watershed that meet the design criteria specified in the stormwater design manual, no limitation of development runoff is required.

(2)

If the downstream analysis demonstrates conditions that exceed the design criteria established in this article and the stormwater design manual within the downstream impact area, the developer shall conduct one or more of the following:

(A)

Identify the required upsizing of any affected downstream structures and any needed drainage easement within the downstream impact area to handle the fully developed watershed conditions within the requirements of the stormwater design manual. Determine the capacity of those downstream facilities to convey:

(i)

Existing watershed conditions;

(ii)

Existing watershed conditions with the proposed development; and

(iii)

Fully developed watershed conditions.

The city may, at its discretion, participate in construction of facilities that correct existing drainage inadequacies and/or convey the fully developed watershed conditions, other than for the proposed development, if adequate funds or other funding agreements are available. Funding options are discussed in section 12.05.010 of this article;

(B)

Limit discharge to existing pre-development conditions or less;

(C)

Acquire suitable drainage easement on the city's behalf to contain the increased runoff to meet the design criteria in this article and the stormwater design manual; or

(D)

Participate in a regional facility that accommodates fully developed watershed conditions as mutually agreed upon with the city. Funding options are identified in section 12.05.010 of this article.

(d)

Drainage improvements required for development.

(1)

Developments for which this article applies shall provide for any new drainage facilities, the improvement of any existing drainage facilities, channel improvements or grading, driveway adjustments, culvert improvements or any other improvement, drainage facility, or work which is necessary to provide for the stormwater drainage requirements specified in the stormwater design manual.

(2)

The developer is required to dedicate drainage easements across the site that will accommodate fully developed watershed conditions. The developer is only required to construct that portion of the drainage system across the site that will convey existing off-site flows and the flows from the proposed site development. Upsizing or phasing the construction of the drainage systems to accommodate fully developed watershed conditions shall be coordinated with the city. Funding for the increased sizing of these facilities shall be in accordance with section 12.05.010 (funding) of this article.

(3)

The developer shall construct drainage improvements that convey stormwater runoff through the proposed development to the site outfall locations in accordance with the design criteria in this article and the stormwater design manual.

(1996 Code, sec. 12.405; Ordinance adopted 11-16-10)

(a)

Design storm frequencies. The calculations of runoff quantities that must be accommodated in drainage facilities, as well as the design flood levels for various drainage structures, are located in subsection (e) of this section and in the stormwater design manual.

(b)

Storm drain design standards. Stormwater design standards are found in the stormwater design manual. This includes but is not limited to channel, street and alley capacity; placement of inlets and manholes; and standard methods and formulas for calculation of flow and depth.

(c)

Lot-to-lot drainage. Existing drainage between developed lots are the responsibility of the affected property owners. Future developments are required to drain surface runoff in accordance with the building code adopted by the city from no more than one residential lot across one other residential lot and then drain into public right-of-way, easement, or drainage system.

(d)

Drainage easements. All stormwater conveyance systems (streets, storm drains, ditches, swales, detention basins, channels, etc.) to be dedicated to and accepted by the city shall be located in the right-of-way or in a drainage easement dedicated to and accepted by the city at the time of final recording of a plat.

(e)

Design criteria.

(1)

The storm frequencies for fully developed watershed conditions shown in the following tables shall be used in storm drainage designs in the city. All drainage features, except for levees and streets as shown, shall be designed to keep the two-year and 100-year floods within the prescribed drainage easements or ROW (right-of-way).

(2)

Velocity limitations are listed in the table below:

(1996 Code, sec. 12.406; Ordinance adopted 11-16-10)

(a)

Lakes and dams.

(1)

Generally. In the event that a property owner or developer desires to create a new pond or lake, or modify an existing pond or lake, or desires to impound stormwater by filling or constructing an above-ground dam, thereby creating a lake, pond, lagoon or basin as part of the development of that property, the criteria listed in the stormwater design manual shall be met before city approval of the impoundment can be given. Ponds or lakes created by excavation of a channel area without erecting a dam above natural ground elevation or in-stream low water check dams are also subject to the criteria. The dam safety requirements of the state must also be met for the construction of dams, lakes and other impoundments.

(2)

Maintenance and liability.

(A)

The owner or developer shall retain their private ownership of the constructed lake, pond or lagoon or basin and shall assume full responsibility for the protection of the general public from any health or safety hazards related to the lake, pond or lagoon constructed.

(B)

The owner or developer shall assume full responsibility for the maintenance of the lake, pond or lagoon or basin constructed. The owner or developer shall keep the city engineer advised of the currently responsible agent for this maintenance.

(b)

Levees. In the event that developers or owners wish to build levees to protect an area from flooding, applicable FEMA guidelines, state dam safety guidelines and the criteria listed in the stormwater design manual shall apply.

(c)

Detention and retention facilities.

(1)

Detention/retention facilities to reduce runoff rates may be required due to inadequate storm drainage facilities or a change in land use resulting in a significant increase in runoff. Inadequate storm drainage facilities to be considered are downstream structures or other identifiable flood-prone areas.

(2)

Detention/retention facilities shall be in compliance with all applicable design requirements of all local, state or federal ordinances, laws or regulations, including the regulations for dam safety of the state commission on environmental quality.

(3)

Detention/retention pond design criteria are outlined in section 12.05.005(e) of this article and the stormwater design manual.

(1996 Code, sec. 12.407; Ordinance adopted 11-16-10; Ord. No. 2020-108, § 2, 11-17-20)

(a)

General standards. In all areas of special flood hazards, the following provisions are required for all new construction and substantial improvements:

(1)

All new construction or substantial improvements shall be designed (or modified) and adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;

(2)

All new construction or substantial improvements shall be constructed by methods and practices that minimize flood damage;

(3)

All new construction or substantial improvements shall be constructed with materials resistant to flood damage;

(4)

All new construction or substantial improvements shall be constructed with electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding;

(5)

All new construction or substantial improvements shall be constructed with materials resistant to flood damage;

(6)

New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from the systems into the floodwaters; and

(7)

On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

(b)

Specific standards. In all areas of special flood hazards, where base flood elevation data has been provided, the following provisions are required:

(1)

Residential construction. New construction and substantial improvement of any residential structure shall have the lowest floor (including basement) elevated to a minimum of two feet above the base flood elevation, one foot above the fully developed 100-year flood elevation, or one foot above the 500-year flood elevation, whichever is more restrictive. A registered professional engineer, architect, or land surveyor shall submit a certification to the floodplain administrator that the standard of this subsection is satisfied.

(2)

Nonresidential construction. New construction and substantial improvements of any commercial, industrial, or other nonresidential structure shall either have the lowest floor (including basement) elevated to at a minimum of two feet above the base flood elevation, one foot above the fully developed 100-year flood elevation, one foot above the 500-year flood elevation, whichever is more restrictive, or, together with attendant utility and sanitary facilities, be designed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. A registered professional engineer or architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice as outlined in this subsection. A record of such certification which includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained by the floodplain administrator.

(3)

Enclosures. New construction and substantial improvements with fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a licensed professional engineer or architect or meet or exceed the following minimum criteria:

(A)

A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.

(B)

The bottom of all openings shall be not higher than one foot above grade.

(C)

Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

(4)

Manufactured homes.

(A)

All manufactured homes to be placed within zone A shall be installed using methods and practices which minimize flood damage. For the purpose of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.

(B)

Manufactured homes that are placed or substantially improved within zones A1-30, AH, and AE on the community's FIRM on sites that must be:

(i)

Outside of a manufactured home park or subdivision;

(ii)

In a new manufactured home park or subdivision;

(iii)

In an expansion to an existing manufactured home park or subdivision; or

(iv)

In an existing manufactured home park or subdivision on which a manufactured home has incurred "substantial damage" as a result of a flood;

[must] be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to one foot above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.

(C)

Require that manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within zones A1-30, AH and AE on the community's FIRM that are not subject to provisions in this article be elevated so that either:

(i)

The lowest floor of the manufactured home is at or above the base flood elevation; or

(ii)

The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement.

(5)

Recreational vehicles. Require that recreational vehicles placed on sites within zones A1-30, AH, and AE on the community's FIRM either:

(A)

Be on the site for fewer than 180 consecutive days;

(B)

Be full licensed and ready for highway use; or

(C)

Meet the permit requirements of this article and the elevation and anchoring requirements for manufactured homes.

A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick-disconnect type utilities and security devices, and has no permanently attached additions.

(c)

Standards for subdivision proposals.

(1)

All proposals for the development of subdivisions, including manufactured home parks and subdivisions, shall meet floodplain development permit requirements of this article.

(2)

Base flood elevation data shall be generated for subdivision proposals and other proposed development, including manufactured home parks and subdivisions, which is greater than 50 lots or five acres, whichever is lesser, if not otherwise provided pursuant to this article.

(3)

All subdivision proposals, including manufactured home parks and subdivisions, shall have adequate drainage provided to reduce exposure to flood hazards.

(4)

All subdivision proposals, including manufactured home parks and subdivisions, shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize or eliminate flood damage.

(d)

Standards for areas of shallow flooding (AO/AH zones). Located within the areas of special flood hazard are areas designated as shallow flooding. These areas have special flood hazard associated with base flood depths of 1 to 3 feet where a clearly defined channel does not exist and where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow. The following provisions apply:

(1)

All new construction and substantial improvements of residential structures shall have the lowest floor (including basement) elevated above the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least two feet if no depth number is specified).

(2)

All new construction and substantial improvements of nonresidential structures shall:

(A)

Have the lowest floor (including basement) elevated above the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least two feet if no depth number is specified); or

(B)

Together with attendant utility and sanitary facilities be designed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads of effects of buoyancy.

(3)

A registered professional engineer or architect shall submit a certification to the floodplain administrator that the standards of this section are satisfied.

(4)

Within zone AH or AO, adequate drainage paths around structures on slopes, to guide floodwaters around and away from proposed structures, are required.

(e)

Floodways. Located within areas of special flood hazard are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters, which carry debris, potential projectiles and erosion potential, the following provisions shall apply:

(1)

Encroachments are prohibited, including fill, new construction, substantial improvements and other development, within the adopted regulatory floodway, unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice by a licensed professional engineer or architect that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharge.

(2)

All new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this article.

(3)

Under the provisions of 44 CFR chapter 1, section 65.12, of the National Flood Insurance Regulations, encroachments within the adopted regulatory floodway that would result in an increase in base flood elevations may be permitted, provided that an application and approval for a conditional FIRM and floodway revision to FEMA is made and received.

(f)

Verification of floodplain alterations.

(1)

Certified minimum proposed finished floor elevations. Prior to final acceptance by the city of utilities, streets or other public construction for projects involving floodplain alterations or adjacent to defined floodplains, creeks, channels and drainageways, a certified statement shall be prepared by a registered public surveyor or licensed professional engineer, showing that all lot elevations, as developed within the subject project, meet or exceed the required minimum finished floor elevations shown on the floodplain development permit. This certification shall be filed with the city engineer.

(2)

Certified elevations of constructed finished floor. In addition, at any time in the future when a building permit is desired for existing platted property which is subject to flooding or carries a specified or recorded minimum finished flood elevation, a registered public surveyor or a licensed professional engineer shall prepare a certified statement that sites are built to the design elevations. The certified survey data showing the property to be at or above the specified elevation shall be furnished to the city engineer for approval. A certificate of compliance with the provisions of this article, pertaining to specified finished floor elevations, shall be required.

(3)

Issuance of building permits. The applicants shall furnish, at their expense, to the city engineer the above certifications and any other certified engineering and surveying information requested by the city engineer to confirm that the required minimum floor and pad elevations have been achieved. Building permits will not be issued until:

(A)

A letter of map revision or amendment has been issued by FEMA; and/or

(B)

Lots and/or sites are certified by a registered public surveyor or a licensed professional engineer that they are elevated from the floodplain according to FEMA-approved revisions to the floodplain and the requirements of this article.

(1996 Code, sec. 12.408; Ordinance adopted 11-16-10)

Editor's note— Ord. No. 2018-146, § 3, adopted Dec. 11, 2018, repealed former § 12.05.009, which pertained to stormwater pollution prevention requirements for construction activity, and derived from the 1996 Code, § 12.409; and an ordinance adopted Nov. 16, 2010.

(a)

On-site drainage improvements. On-site drainage system improvements implemented by a proposed development to comply with the requirements of this article shall be financed entirely by the developer. If the city determines that enlargement of the on-site drainage facility beyond the requirements of this article is beneficial to the city, the city shall fund the difference between the enlarged facility and the required on-site improvements, based on available funds.

(b)

Off-site drainage improvements. Off-site drainage system improvements implemented by a proposed development to comply with the requirements of this article shall be financed entirely by the developer. If the city determines that enlargement of the off-site improvements beyond the requirements of this article is beneficial to the city, the city shall fund the difference between the enlarged improvements and the off-site improvements necessary to comply with the provisions of this article, based on available funds.

(c)

Predetermined facilities agreement. The initial developer may recover a portion of the cost from the adjacent property owner, the developer, or the city in accordance with a predetermined facilities agreement.

(1996 Code, sec. 12.410; Ordinance adopted 11-16-10)

(a)

Appeal. Any person aggrieved by a decision of the city engineer may appeal from any order, requirement, decision or determination of the city engineer to the city manager. The aggrieved person shall file an appeal in writing with the city manager within seven days from the date of the decision. If no resolution of the appeal can be reached with the city manager within 28 days, the aggrieved person may appeal in writing to the city council.

(b)

Variance.

(1)

Deviations from the provisions of this article will not be permitted unless the following criteria are met:

(A)

The owners directly affected by the deviation are in written agreement; or

(B)

Each of the following is met:

(i)

It can be clearly shown by approved procedures that the deviation will not adversely affect conditions either upstream or downstream of the point of deviation;

(ii)

The deviation is not in conflict with any other plans adopted by the city, the state or federal agencies;

(iii)

A showing of good and sufficient cause;

(iv)

A determination that failure to grant the variance would result in hardship to the applicant; and

(v)

A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety or extraordinary public expense, create nuisances, cause fraud on or victimization of the public or conflict with existing local, state, or federal laws or regulations.

(2)

Requests for deviation shall be reviewed and approved or disapproved by the city engineer.

(3)

Variances concerning development permits may be issued for the reconstruction, rehabilitation or restoration of structures listed on the National Register of Historic Places or the state inventory of historic places, without regard to the procedures set forth in the remainder of this section, provided the proposal work will not preclude the structure's continued designation as a historic structure. Variances for any type of permit or storm drainage facilities shall be issued only upon a determination that the variance is the minimum necessary to afford relief considering the flood hazard, drainage problems and soil loss.

(4)

Any applicant to whom a variance for building or renovating in a floodplain is granted shall be given written notice that the structure will be permitted to be built with a lowest floor elevation below the base flood elevation, and that the cost of flood insurance will be commensurate with the increased risk resulting from the reduced lowest floor elevation.

(1996 Code, sec. 12.411; Ordinance adopted 11-16-10)

(a)

Compliance date. This article shall become effective on November 16, 2010, and shall apply to all new construction and substantial improvements occurring after the effective date, except that the provisions of the current land development and subdivision ordinance shall continue to apply.

(b)

Periodic review of ordinance. The city engineer shall review this ordinance on a periodic basis. Any recommended ordinance revisions shall be provided to the city council for consideration following reviews.

(1996 Code, sec. 12.412; Ordinance adopted 11-16-10)