Chapter 18.60
USE REGULATION FOR “E-S” ENVIRONMENTALLY SENSITIVE OVERLAY DISTRICT Revised 8/24
Sections:
18.60.020 Floodplains. Revised 8/24
18.60.030 Repealed. Revised 8/24
18.60.040 Repealed. Revised 8/24
18.60.050 Repealed. Revised 8/24
18.60.060 Repealed. Revised 8/24
18.60.010 Purpose.
Within the “E-S” environmentally sensitive overlay district, areas are identified per Chapter 18.15 BHCC. This chapter shall prescribe permitted uses, conditional uses, and performance standards for those areas. Development within the overlay district must conform to the requirements of both the zoning district and the overlay district or the most restrictive of the chapter’s requirements. [Ord. 109, 2010; Ord. 36 § 17, 1995. Code 2009 App. A, § 17.]
18.60.020 Floodplains. Revised 8/24
A. Intent. It is the intent of this section to promote the public health, safety and general welfare by minimizing those flood losses described in Chapter 18.55 BHCC, findings of fact, with provisions designed to:
1. Preserve and protect the natural character of the lands within this district, and their values for flood control and water holding capacity, maintenance of water quality, benefits of recharge of ground water, wildlife, recreation and conservation, reduced soil erosion and sedimentation, and woodland management;
2. Reserve sufficient floodplain area for the conveyance of flood flows so that flood heights and velocities will not be increased;
3. Restrict or prohibit uses which are dangerous to health, safety, or property in times of flood or which cause excessive increases in flood heights or velocities;
4. Require that uses vulnerable to floods, including public utilities which serve such uses, be protected against flood damage at the time of initial construction, or substantial improvement;
5. Protect individuals from buying lands which are unsuited for intended purposes because of flood hazards;
6. Reduce public expenditures for construction of flood control works, emergency action and postdisaster assistance;
7. Reduce loss of life, injury, and hardship due to floods; and
8. Assure that eligibility is maintained for property owners in the County to purchase flood insurance through the National Flood Insurance Program.
B. Warning and Disclaimer of Liability. The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on engineering and scientific methods of study. Larger floods may occur on rare occasions. Flood heights may be increased by manmade or natural causes, such as ice jams and bridge openings restricted by debris. This chapter does not imply that areas outside the floodplain or land uses permitted within such areas will be free from flooding or flood damages. This chapter shall not create liability on the part of Black Hawk County or any officer or employee thereof for any flood damages that result from reliance on this chapter or any administrative decision lawfully made thereunder.
C. Divisions of the Floodplain.
1. Floodway District (“F-W”) – General Intent. It is the intent of the floodway district (“F-W”) that the identified area is designed to carry flood waters and should be protected from developmental encroachment.
a. Principal Permitted Uses. The following uses shall be permitted within the floodway district to the extent they are not prohibited by any other ordinance (or allowed according to the underlying zoning district) and provided they do not require placement of structures, dwellings, factory-built homes, fill or other obstruction, the storage of materials or equipment, excavation, or alteration of a watercourse:
i. Agricultural uses such as general farming, pasture, grazing, outdoor plant nurseries, horticulture, viticulture, truck farming, forestry, sod farming, and wild crop harvesting, but not including livestock feedlots.
ii. Industrial commercial uses such as loading areas, parking areas, and airport landing strips.
iii. Private and public recreational uses such as golf courses, tennis courts, driving ranges, archery ranges, picnic grounds, boat launching ramps, swimming areas, parks, wildlife and nature preserves, game farms, fish hatcheries, shooting preserves, target ranges, trap and skeet ranges, hunting and fishing areas, hiking and horseback riding trails.
iv. Residential uses such as lawns, gardens, parking areas and play areas.
v. Such other open space uses similar in nature to the above uses.
b. Conditional Uses. The following uses which involve structures (temporary or permanent), fill, storage or materials or equipment may be permitted only upon issuance of a conditional use permit. Such uses must also meet the applicable provisions of the floodway district performance standards.
i. Uses or structures accessory to open space uses.
ii. Circuses, carnivals, and similar transient amusement enterprises.
iii. Extraction of sands, gravel, and other materials.
iv. Marinas, boat rentals, docks, piers, and wharves.
v. Utility transmission lines, underground pipelines.
vi. Other uses similar in nature to uses described above which are consistent with the provisions of the performance standards and the general spirit and purpose of this section.
c. Performance Standards. All floodway district uses allowed as a permitted or conditional use shall meet the following standards:
i. No development shall be permitted in the floodway district that would result in any increase in the 100-year flood level. Consideration of the effects of any development on flood levels shall be based upon the assumption that an equal degree of development would be allowed for similarly situated lands.
ii. All development within the floodway district shall:
(A) Be consistent with the need to minimize flood damage.
(B) Use construction methods and practices that will minimize flood damage.
(C) Use construction materials and utility equipment that are resistant to flood damage.
iii. No development shall affect the capacity or conveyance of the channel or floodway or any tributary to the main stream, drainage ditch, or any other drainage facility or system.
iv. Structures, buildings, recreational vehicles and sanitary and utility systems, if permitted, shall meet the applicable performance standards of the shallow flooding (“S-F”) and floodway fringe (“F-F”) districts and shall be constructed or aligned to present the minimum possible resistance to flood flows.
v. Structures, if permitted, shall have a low flood damage potential and shall not be for human habitation.
vi. Storage of materials or equipment that are buoyant, flammable, explosive or injurious to human, animal or plant life is prohibited. Storage of other material may be allowed if readily removable from the floodway district within the time available after flood warning.
vii. Watercourse alterations or relocations (channel changes and modifications) must be designed to maintain the flood carrying capacity within the altered or relocated portion. In addition, such alterations or relocations must be approved by the Department of Natural Resources.
viii. Any fill allowed in the floodway must be shown to have some beneficial purpose and shall be limited to the minimum amount necessary.
ix. Pipeline river or stream crossings shall be buried in the streambed and banks or otherwise sufficiently protected to prevent rupture due to channel degradation and meandering or due to the action of flood flows.
x. Mobile homes shall not be permitted.
xi. Recreational vehicles placed on sites within the special flood hazard areas on the community's official floodplain map shall (A) be on the site for fewer than 180 consecutive days, and (B) be fully licensed and ready for highway use. 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.
2. Floodway Fringe District (“F-F”) – General Intent. It is the intent of the floodway fringe district that the identified area is designed to preserve and protect the natural character of the lands within the district and their values for flood control and water holding capacity. The areas within this district should be protected from developmental encroachment.
a. Principal Permitted Uses. The following uses shall be permitted within the “F-F” floodway fringe district to the extent they are not prohibited by any other ordinance (or underlying zoning district) and provided they do not require the placement of dwellings or factory-built homes. All uses shall meet applicable performance standards of the floodway fringe district.
i. Any use permitted in a floodway district as a principal permitted use.
b. Conditional Uses. The following uses involving structures (temporary or permanent), fill, storage of materials or equipment may be permitted only upon issuance of a conditional use permit. Such use must also meet the applicable provisions of the floodway fringe district performance standards.
i. Any conditional use permitted in a floodway district.
ii. Subdivisions and new or substantially improved residential buildings, in accordance with subsection (C)(2)(c) of this section.
c. Performance Standards. All development must be consistent with the need to minimize flood damage and shall meet the following applicable performance standards. Until a regulatory floodway is designated, no development may increase the 100-year elevation more than one foot.
i. All development shall: (A) be designed and adequately anchored (including factory-built homes) to prevent flotation, collapse or lateral movement of the structure, (B) be constructed with materials and utility equipment resistant to flood damage, and (C) be constructed by methods and practices that minimize flood damage.
ii. New or Substantially Improved Residential Structures. New or substantially improved residential structures shall have the lowest floor (including basements) elevated a minimum of three feet above the 100-year flood level. The preferred method of elevation shall be on piles, posts, piers or columns, or on walls or a crawl space. Enclosures created by a crawl space or solid walls below the base flood elevation shall only be used for building access, vehicle parking, and storage of materials that have low damage potential. Enclosures shall be constructed of flood resistant materials and utilities must be raised a minimum of three feet above the base flood elevation. Enclosures must be floodable and have openings as provided in subsection (C)(4) of this section. The methods used must be adequate to support the structure as well as withstand the various forces and hazards associated with flooding. Elevation on fill shall be discouraged to protect flood storage capacity and to prevent flood heights from increasing due to a loss of flood storage capacity. When permitted, elevation on fill shall be upon compacted fill which shall, at all points, be no lower than three feet above the 100-year flood level and extend at such elevation at least 18 feet beyond the limits of any structure erected thereon. Elevation on fill shall not be permitted when the natural grade is more than two feet below the base flood elevation unless compensatory storage is created to offset any loss of flood storage. Compensatory storage shall not include excavation areas that create ponds or low-lying areas likely to have their storage capacity exhausted by non-floodwaters. All new or substantially improved residential structures shall be provided with a means of access that will be passable by wheeled vehicles during the 100-year flood.
iii. Nonresidential Structures. All new or substantially improved nonresidential structures shall have the lowest floor (including basement) elevated a minimum of three feet above the 100-year flood level, or together with attendant utility and sanitary systems, be flood proofed to such a level. When floodproofing is utilized, a professional engineer registered in the state of Iowa shall certify that the floodproofing methods used are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 100-year flood; and that the structure, below the 100-year flood level, is watertight with walls substantially impermeable to the passage of water. A record of the certification indicating the specific elevation (in relation to North American Vertical Datum 1988) to which any structures are flood proofed shall be maintained by the Zoning Administrator.
iv. All New and Substantially Improved Structures.
(A) Fully enclosed areas below the “lowest floor” (not including basements) that 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 registered professional engineer or meet or exceed the following minimum criteria:
(1) 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.
(2) The bottom of all openings shall be no higher than one foot above grade.
(3) Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.
Such areas shall be used solely for parking of vehicles, building access and low damage potential storage.
(B) New and substantially improved structures must 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.
(C) New and substantially improved structures must be constructed with electrical meter, electrical service panel box, hot water heater, heating, air conditioning, ventilation equipment (including ductwork), and other similar machinery and equipment elevated (or in the case of nonresidential structures, optionally floodproofed to) a minimum of three feet above the base flood elevation.
(D) New and substantially improved structures shall be constructed with plumbing, gas lines, water/gas meters and other similar service utilities either elevated (or in the case of nonresidential structures, optionally floodproofed to) a minimum of three feet above the base flood elevation or designed to be watertight and withstand inundation to such a level.
v. Factory-Built Homes.
(A) Factory-built homes, including those placed in existing factory-built home parks or subdivisions, shall be anchored to resist flotation, collapse, or lateral movement by providing over-the-top and frame ties to ground anchors. Specific requirements are that:
(1) Over-the-top ties be provided at each of the four corners of the factory-built home with two additional ties per side at intermediate locations for factory-built homes 50 feet or more in length or one such tie for factory-built homes less than 50 feet in length;
(2) Frame ties be provided at each corner of the home with five additional ties per side at intermediate points for factory-built homes 50 feet in length or four such ties for homes less than 50 feet in length;
(3) All components of the anchoring system be capable of carrying a force of 4,800 pounds; and
(4) Any additions to the factory-built home be similarly anchored.
(B) Factory-built homes, including those placed in existing factory-built home parks or subdivisions, shall be elevated on a permanent foundation such that the lowest floor of the structure is a minimum of three feet above the 100-year flood level.
(C) Factory-built homes not being placed in existing factory-built home parks or subdivisions shall be placed on lots or pads elevated so that the lowest floor of the factory-built home will be a minimum of three feet above the 100-year flood level. In addition, the tie-down specifications enumerated within subsection (C)(2)(c)(v)(A) of this section must be met and adequate surface drainage and access for a hauler must be provided. New factory-built home parks, expansions to existing factory-built home parks, and factory-built home parks where the repair, reconstruction or improvement of the streets, utilities, and pads equals or exceeds 50 percent or more of the value of the streets, utilities and pads before the repair, reconstruction or improvement has commenced shall provide:
(1) Lots or pads that have been elevated so that the lowest floor of the factory-built homes will be a minimum of three feet above the 100-year flood level;
(2) Adequate surface drainage;
(3) Access for a hauler; and
(4) Ground anchors for factory-built homes.
vi. Utility and Sanitary Systems.
(A) All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system as well as the discharge of effluent into flood waters. Waste water treatment facilities shall be provided with a level of flood protection equal to or greater than three feet above the 100-year flood elevation.
(B) On-site waste disposal systems shall be located or designed to avoid impairment to the system or contamination from the system during flooding.
(C) New or replacement water supply systems shall be designed to eliminate infiltration of flood waters into the system. Water supply treatment facilities shall be provided with a level of protection equal to or greater than three feet above the 100-year flood elevation.
(D) Utilities such as gas and electrical systems shall be located and constructed to minimize or eliminate flood damage to the system and the risk associated with such flood damaged or impaired systems.
vii. Recreational vehicles placed on sites within the special flood hazard areas on the community’s official floodplain map shall (A) be on the site for fewer than 180 consecutive days, and (B) be fully licensed and ready for highway use. 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.
viii. Storage of materials and equipment that are flammable, explosive or injurious to human, animal or plant life is prohibited unless elevated a minimum of three feet above the 100-year flood level. Other material and equipment must either be similarly elevated or: (A) not be subject to major flood damage and be anchored to prevent movement due to flood waters or (B) be readily removable from the area within the time available after flood warning.
ix. Flood control structural works such as levees, flood walls, etc., shall provide, at a minimum, protection from a 100-year flood with a minimum of three feet of design freeboard and shall provide for adequate interior drainage. In addition, structural flood control works shall be approved by the Department of Natural Resources.
x. Watercourse alterations or relocations must be designed to maintain the flood carrying capacity within the altered or relocated portion. In addition, the Department of Natural Resources must approve such alterations or relocations.
xi. Subdivisions (including factory-built home parks and subdivisions) shall be consistent with the need to minimize flood damages and shall have adequate drainage provided to reduce exposure to flood damage. Development associated with subdivision proposals (including the installation of public utilities) shall meet the applicable performance standards of this title. Subdivision proposals intended for residential development shall provide all lots with a means of vehicular access that will remain dry during occurrence of the 100-year flood. Proposals for subdivisions greater than five acres or 50 lots (whichever is less) shall include base flood elevation data for those areas located within the floodway fringe (overlay) district.
xii. Detached garages, sheds, and similar structures that are incidental to a residential use are exempt from the base flood elevation requirements where the following criteria are satisfied:
(A) The structure shall be designed to have low flood damage potential. Its size shall not exceed 600 square feet. Those portions of the structure located less than one foot above the base flood elevation must be constructed of flood-resistant materials.
(B) The structure shall be used solely for low flood damage potential purposes such as vehicle parking and limited storage. The structure shall not be used for human habitation.
(C) The structure shall be constructed and placed on the building site so as to offer minimum resistance to the flow of floodwaters.
(D) The structure shall be firmly anchored to resist flotation, collapse, and lateral movement which may result in damage to other structures.
(E) The structure’s service facilities such as electrical and heating equipment shall be elevated or floodproofed to at least one foot above the base flood elevation.
(F) The structure’s walls shall include openings that satisfy the provisions of subsection (C)(4) of this section.
Exemption from the base flood elevation requirements for such a structure may result in increased premium rates for flood insurance coverage of the structure and its contents. A professional engineer registered in the state of Iowa shall certify all requirements are met.
xiii. Pipeline river and stream crossings shall be buried in the streambed and banks, or otherwise sufficiently protected to prevent rupture due to channel degradation and meandering.
xiv. All new or substantially improved maximum damage potential development shall have the lowest floor (including basement) elevated a minimum of one foot above the elevation of the 500-year flood, or together with attendant utility and sanitary systems, be floodproofed to such a level. When floodproofing is utilized, a professional engineer registered in the state of Iowa shall certify that the floodproofing methods used are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 0.2 percent annual chance flood; and that the structure, below the 0.2 percent annual chance flood elevation is watertight with walls substantially impermeable to the passage of water. A record of the certification indicating the specific elevation (in relation to North American Vertical Datum 1988) to which any structures are floodproofed shall be maintained by the Zoning Administrator. Where 0.2 percent chance flood elevation data has not been provided in the Flood Insurance Study, the Iowa Department of Natural Resources shall be contacted to compute such data. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determinations.
3. General Floodplain (Overlay) District (“G-F”) – General Intent. The “G-F” general floodplain (overlay) district reflects those areas which would be inundated during a 100-year flood, but for which specific flood elevations and floodway and floodway fringe limits have not been established. It is the intent of the “G-F” district to impede the restrictions and performance standards of the “F-W” and “F-F” districts after a determination is made to identify the floodway and floodway fringe areas on an individual basis. The areas within this district should be protected from development encroachment. Any development which involves placement of structures, factory-built homes, fill or other obstructions; the storage of materials or equipment; excavation or alteration of a watercourse may be allowed only upon a determination by the Department of Natural Resources to determine (a) whether the land involved is either wholly or partly within the floodway or floodway fringe and (b) the 100-year flood level. Until a regulatory floodway is designated, no development may increase the 100-year elevation more than one foot. The applicant shall be responsible for providing the Department of Natural Resources with sufficient technical information to make the determination.
a. Principal Permitted Uses. As specified, principal permitted uses for either the “F-W” floodway or the “F-F” floodway fringe districts.
b. Conditional Uses. As specified, conditional uses for either the “F-W” floodway or the “F-F” floodway fringe districts.
c. Performance Standards. The applicant shall provide the Department of Natural Resources with sufficient technical information to make a determination as to whether the land involved is either partly or wholly within the floodway or floodway fringe and to determine the 100-year flood elevation.
i. All uses or portions thereof to be located in the floodway as determined by the Department of Natural Resources shall meet the applicable standards of the “F-W” floodway district.
ii. All uses or portions thereof to be located in the floodway fringe as determined by the Department of Natural Resources shall meet the standards of the “F-F” floodway fringe district.
4. Shallow Flooding District (“S-F”).
a. Principal Permitted Uses. All development within the shallow flooding district shall be permitted to the extent that they are not prohibited by any other ordinance (or underlying zoning district) and provided they meet the applicable performance standards of the shallow flooding (overlay) district.
b. Performance Standards. The performance standards for the shallow flooding (overlay) district shall be the same as the performance standards for the floodway fringe district with the following exceptions:
i. In shallow flooding areas designated as an AO Zone on the flood insurance rate map, the minimum flood proofing/flood protection elevation shall be equal to the number of feet as specified on the rate map (or a minimum of 2.0 feet if no number is specified) above the highest natural grade adjacent to the structure.
ii. In shallow flooding areas designated as an AH Zone on the flood insurance rate map, the minimum flood proofing/flood protection elevation shall be equal to the elevation as specified on the flood insurance rate map.
iii. In shallow flooding areas designated as either an AO or AH Zone on the flood insurance rate map, drainage paths are required around structures on slopes to adequately guide floodwaters around and away from proposed structures. [Ord. 147, 2024; Ord. 112, 2011; Ord. 109, 2010; Ord. 104, 2009; Ord. 82, 2003; Ord. 63, 2001; Ord. 36 § 17(A), 1995. Code 2009 App. A, § 17(A).]
18.60.030 Poor bearing capacity soils. Revised 8/24
Repealed by Ord. 147. [Ord. 36 § 17(B), 1995. Code 2009 App. A, § 17(B).]
18.60.040 Excessive slopes. Revised 8/24
Repealed by Ord. 147. [Ord. 36 § 17(C), 1995. Code 2009 App. A, § 17(C).]
18.60.050 Aquifer recharge areas. Revised 8/24
Repealed by Ord. 147. [Ord. 36 § 17(D), 1995. Code 2009 App. A, § 17(D).]
18.60.060 Surface waters. Revised 8/24
Repealed by Ord. 147. [Ord. 36 § 17(E), 1995. Code 2009 App. A, § 17(E).]