Chapter 15.24 FLOOD DAMAGE PREVENTION

The Legislature of the state of Washington has delegated the responsibility to local governmental units to adopt regulations designed to promote the public health, safety and general welfare of its citizenry. [Ord. 88-14 § 1.1, 1988].

15.24.020 Findings of fact.

A. The flood hazard areas of Castle Rock are subject to periodic inundation which results in loss of life and property, health and safety hazards, disruption of commerce and governmental services, extraordinary public expenditures for flood protection and relief, and impairment of the tax base, all of which adversely affect the public health, safety and general welfare.

B. These flood losses are caused by the cumulative effect of obstructions in areas of special flood hazards which increase flood heights and velocities, and when inadequately anchored, damage uses in other areas. Uses that are inadequately floodproofed, elevated or otherwise protected from flood damage also contribute to the flood loss. [Ord. 88-14 § 1.2, 1988].

15.24.030 Statement of purpose.

It is the purpose of this chapter to promote the public health, safety and general welfare, and to minimize public and private losses due to flood conditions in specific areas by provisions designed:

A. To protect human life and health;

B. To minimize expenditure of public money and costly flood control projects;

C. To minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;

D. To minimize prolonged business interruptions;

E. To minimize damage to public facilities and utilities such as water and gas mains, electric, telephone and sewer lines, streets and bridges located in areas of special flood hazard;

F. To help maintain a stable tax base by providing for the sound use and development of areas of special flood hazard so as to minimize future flood blight areas;

G. To ensure that potential buyers are notified that property is in an area of special flood hazard;

H. To ensure that those who occupy the areas of special flood hazard assume responsibility for their actions; and

I. To participate in and maintain eligibility for flood insurance and disaster relief. [Ord. 2023-05, 2023; Ord. 88-14 § 1.3, 1988].

15.24.040 Methods of reducing flood losses.

In order to accomplish its purposes, this chapter includes methods and provisions for:

A. Restricting or prohibiting uses which are dangerous to health, safety and property due to water or erosion hazards, or which result in damaging increases in erosion or in flood heights or velocities;

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

C. Controlling the alteration of natural floodplains, stream channels and natural protective barriers, which help accommodate or channel floodwaters;

D. Controlling filling, grading and other development which may increase flood damage; and

E. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or may increase flood hazards in other areas. [Ord. 88-14 § 1.4, 1988].

Article II. Definitions

15.24.050 Definitions.

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

“Alteration of watercourse” means any action that will change the location of the channel occupied by water within the banks of any portion of a riverine waterbody.

“AO zones” or “shallow flooding areas” means an area that appears on FIRMS as AO zones with depth designations. The base flood depths in these zones range from one to three feet above ground where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. Further provisions for AO zones are laid out in CRMC 15.24.270 for residential structures, and CRMC 15.24.280 for nonresidential structures.

“Appeal” means a request for a review of the building official’s or their designee’s interpretation of any provision of this chapter or a request for a variance.

“Area of shallow flooding” means a designated AO or AH zone on the Flood Insurance Rate Map (FIRM). The base flood depths range from one to three feet, a clearly defined channel does not exist, the path of flooding is unpredictable and indeterminate, and velocity flow may be evident. AO is characterized as sheet flow and AH indicates ponding.

“Area of special flood hazard” means the land in the floodplain within a community subject to a one percent or greater chance of flooding in any given year. Designation on the FIRM always includes the letter A. “Special flood hazard area” is synonymous in meaning with the phrase “area of special flood hazard.”

“ASCE 24” means the most recently published version of ASCE 24, Flood Resistant Design and Construction, published by the American Society of Civil Engineers.

“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year (also referred to as the “100-year flood”).

“Base flood elevation (BFE)” means the elevation to which floodwater is anticipated to rise during the base flood.

“Basement” means any area of the building having its floor sub-grade (below ground level) on all sides.

“Building” is synonymous with “structure.”

“Building code” means the currently effective versions of the International Building Code and the International Residential Code adopted by the state of Washington and city of Castle Rock.

“Critical facility” means a facility for which even a slight chance of flooding might be too great. Critical facilities include, but are not limited to, schools, nursing homes, hospitals, police, fire and emergency response installations, and installations which produce, use or store hazardous materials or hazardous waste.

“Development” means any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations located within the area of special flood hazard.

“Elevated building” means, for insurance purposes, a nonbasement building that has its lowest elevated floor raised above ground level by foundation walls, shear walls, posts, piers, pilings, or columns.

“Elevation certificate” means an administrative tool of the National Flood Insurance Program (NFIP) that can be used to provide elevation information, to determine the proper insurance premium rate, and to support a request for a letter of map amendment (LOMA) or letter of map revision based on fill (LOMR-F).

Essential Facility. This term has the same meaning as “essential facility” defined in ASCE 24. Table 1-1 in ASCE 24-14 further identifies building occupancies that are essential facilities.

“FEMA” means the Federal Emergency Management Agency.

“Flood” or “flooding” means:

1. A general and temporary condition of partial or complete inundation of normally dry land areas from:

a. The overflow of inland or tidal waters.

b. The unusual and rapid accumulation or runoff of surface waters from any source.

c. Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in subsection (1)(b) of this definition and are akin to a river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water and deposited along the path of the current.

2. The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined in subsection (1)(a) of this definition.

“Flood elevation study” means an examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards. Also known as a Flood Insurance Study (FIS).

“Flood Insurance Rate Map (FIRM)” means the official map on which the Federal Emergency Management Administration has delineated both the areas of special flood hazards and the risk premium zones applicable to the community. A FIRM that has been made available digitally is called a digital Flood Insurance Rate Map (DFIRM).

“Floodplain” or “flood prone area” means any land area susceptible to being inundated by water from any source. See “Flood or flooding.”

“Floodplain administrator” means the community official designated by title to administer and enforce the floodplain management regulations.

“Floodproofing” means any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate risk of flood damage to real estate or improved real property, water and sanitary facilities, structures, and their contents. Floodproofed structures are those that have the structural integrity and design to be impervious to floodwater below the base flood elevation.

“Floodway” means 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. Also referred to as “regulatory floodway.”

“Functionally dependent use” means a use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, and does not include long-term storage or related manufacturing facilities.

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

“Historic structure” means 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 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.

“Lowest floor” means 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 nonelevation design requirements of this chapter found at CRMC 15.24.270(B).

“Manufactured home” means a single-family residence constructed after June 15, 1976, in accordance with state and federal requirements for manufactured homes which:

1. Is comprised of at least two fully enclosed parallel sections each of not less than 12 feet wide by 36 feet long;

2. Was originally constructed with and now has a composition or wood shake or shingle, coated metal, or similar roof of nominal 3:12 pitch; and

3. Has exterior siding similar in appearance to siding materials commonly used on conventional site-built Uniform Building Code single-family residences.

“Manufactured home park or subdivision” means a plot of ground divided into lots or sites under the ownership and/or management of one person for the purpose of locating manufactured homes for dwelling purposes.

“Mean sea level” means, for purposes of the National Flood Insurance Program, the vertical datum to which base flood elevations shown on a community’s Flood Insurance Rate Map are referenced.

“New construction” means structures for which the start of construction commenced on or after the effective date of the ordinance codified in this chapter.

“One-hundred-year flood or 100-year flood” is synonymous with “base flood.”

“Reasonably safe from flooding” means development that is designed and built to be safe from flooding based on consideration of current flood elevation studies, historical data, high water marks and other reliable data known to the community. In unnumbered A zones where flood elevation information is not available and cannot be obtained by practicable means, reasonably safe from flooding means that the lowest floor is at least two feet above the highest adjacent grade.

“Recreational vehicle” means a vehicle that is:

1. Built on a single chassis;

2. Four hundred square feet or less when measured at the largest horizontal projection;

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.

“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 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 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 foundation 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.

“Structure” means that which is built or constructed, an edifice or building or structure, such as foundations, bearing walls, columns, beams, floor or floor joists, girders or rafters, or changes in the exterior dimensions of the building or structure, or increase in floor space. A “structure” for floodplain management purposes also means a walled and roofed building including a gas or liquid storage tank that is principally aboveground, as well as a manufactured home.

“Substantial damage” means damage of any origin sustained by a structure whereby the cost of restoring the structure to its before damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.

Substantial Improvement.

1. “Substantial improvement” means any repair, reconstruction or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure either:

a. Before the improvement or repair is started; or

b. If the structure has been damaged and is being restored, before the damage occurred. For the purposes of this definition, substantial improvement is considered to occur when the first alteration of any wall, ceiling, floor or other structural part of the building commences, whether or not that alteration affects the external dimensions of the structure.

2. The term does not, however, include either:

a. Any project for improvement of a structure to comply with existing state or local health, sanitary or safety code specifications which are solely necessary to assure safe living conditions; or

b. Any alteration of a structure listed on the National Register of Historic Places or a State Inventory of Historic Places.

“Variance” means a grant of relief from the requirements of this chapter which permits construction in a manner that would otherwise be prohibited by this chapter. Criteria for a floodplain variance is outlined in CRMC 15.24.170.

“Water dependent” means a structure for commerce or industry which cannot exist in any other location and is dependent on the water by reason of the intrinsic nature of its operations.

“Water surface elevation” means the height, in relation to the vertical datum utilized in the applicable flood insurance study of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas. [Ord. 2023-05, 2023; Ord. 2015-12 § 1, 2015; Ord. 88-14 § 2.0, 1988].

Article III. General Provisions

15.24.060 Lands to which this chapter applies.

This chapter shall apply to all areas of special flood hazards within the jurisdiction of Castle Rock. [Ord. 88-14 § 3.1, 1988].

15.24.070 Basis for establishing the areas of special flood hazard.

Frequently flooded areas may include lands outside of the Federal Emergency Management Agency-defined floodplains and shall include areas identified on the Flood Insurance Rate Maps. Those areas of special flood hazard identified by the Federal Emergency Management Administration are identified in a scientific and engineering report entitled Flood Insurance Study No. 53015CV001A – Cowlitz County, Washington and Incorporated Areas, Vols. 1 – 3, December 16, 2015, with accompanying Flood Insurance Rate Maps and any revisions thereto. The Flood Insurance Study and accompanying maps are hereby adopted by reference, declared to be a part of this chapter, and are available for public review in the city clerk-treasurer’s office, City Hall, 141 A Street SW, Castle Rock, Washington. [Ord. 2015-12 § 1, 2015; Ord. 2001-11, 2001; Ord. 93-6, 1993; Ord. 88-14 § 3.2, 1988].

15.24.075 Compliance.

All development within special flood hazard areas is subject to the terms of this chapter and other applicable regulations. [Ord. 2023-05, 2023].

15.24.080 Penalties for noncompliance.

No structure or land shall hereafter be constructed, located, extended, converted or altered without full compliance with the terms of this chapter and other applicable regulations. Violation of the provisions of this chapter by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions) shall constitute a misdemeanor. Any person who violates this chapter or fails to comply with any of its requirements shall upon conviction thereof be fined not more than $500.00 or imprisoned for not more than 180 days, or both, for each violation, and in addition shall pay all costs and expenses involved in the case. Nothing herein contained shall prevent Castle Rock from taking such other lawful action as is necessary to prevent or remedy any violation. [Ord. 88-14 § 3.3, 1988].

15.24.090 Abrogation and greater restrictions.

This chapter is not intended to repeal, abrogate or impair any existing easements, covenants or deed restrictions. However, where this chapter and another ordinance, easement, covenant or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail. [Ord. 88-14 § 3.4, 1988].

15.24.100 Interpretation.

In the interpretation and application of this chapter, all provisions shall be:

A. Considered as minimum requirements;

B. Liberally construed in favor of the governing body; and

C. Deemed neither to limit nor repeal any other powers granted under state statutes. [Ord. 88-14 § 3.5, 1988].

15.24.110 Warning and disclaimer of liability.

The degree of flood protection required by this chapter is considered reasonable for regulatory purposes and is based on scientific and engineering considerations. Larger floods can and will occur on rare occasions. Flood heights may be increased by manmade or natural causes. This chapter does not imply that land outside the areas of special flood hazards or uses permitted within such areas will be free from flooding or flood damages. This chapter shall not create liability on the part of Castle Rock, any officer or employee thereof, or the Federal Emergency Management Administration, for any flood damages that result from reliance on this chapter or any administrative decision lawfully made hereunder. [Ord. 2015-12 § 1, 2015; Ord. 88-14 § 3.6, 1988].

15.24.115 Severability.

This chapter and the various parts thereof are hereby declared to be severable. Should any section of this chapter be declared by the courts to be unconstitutional or invalid, such decision shall not affect the validity of the chapter as a whole, or any portion thereof other than the section so declared to be unconstitutional or invalid. [Ord. 2023-05, 2023].

Article IV. Administration

15.24.120 Establishment of development permit.

Development permits are established as set out in CRMC 15.24.130 and 15.24.140. [Ord. 88-14 § 4.1, 1988].

15.24.130 Development permit – Required.

A development permit shall be obtained before construction or development begins within any area of special flood hazard established in CRMC 15.24.070. The permit shall be for all structures including manufactured homes, as set forth in Article II of this chapter, and for all development including fill and other activities, also as set forth in Article II of this chapter. [Ord. 88-14 § 4.1-1, 1988].

15.24.140 Application for development permit.

Application for a development permit shall be made on forms furnished by the building official or their designee and may include but not be limited to: plans in duplicate drawn to scale showing the nature, location, dimensions and elevations of the area in question; existing or proposed structures, fill, storage of materials, drainage facilities and the location of the foregoing. Specifically, the following information is required:

A. Elevation in relation to mean sea level of the lowest floor (including basement) of all structures;

B. Elevation in relation to mean sea level to which any structure has been floodproofed;

C. Certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet the floodproofing criteria in CRMC 15.24.280;

D. Description of the extent to which a watercourse will be altered or relocated as a result of proposed development;

E. Where development is proposed in a floodway, an engineering analysis indicating no rise of the base flood elevation; and

F. Any other such information that may be reasonably required by the floodplain administrator in order to review the application. [Ord. 2023-05, 2023; Ord. 88-14 § 4.1-2, 1988].

15.24.150 Building official designated as administrator.

The building official or their designee is appointed to administer and implement this chapter by granting or denying development permit applications in accordance with its provisions. [Ord. 2023-05, 2023; Ord. 88-14 § 4.2, 1988].

15.24.160 Duties and responsibilities of the building official.

Duties of the building official or their designee shall include, but not be limited to:

A. Permit Review.

1. Review all development permits to determine that the permit requirements of this chapter have been satisfied.

2. Review all development permits to determine that all necessary permits have been obtained from those federal, state or local governmental agencies from which prior approval is required.

3. Review all development permits to determine if the proposed development is located in the floodway. If located in the floodway, assure that the provisions of CRMC 15.24.310 are met.

4. The site is reasonably safe from flooding.

5. Notify FEMA when annexations occur in the special flood hazard area.

B. Use of Other Base Flood Data. When base flood elevation data has not been provided in accordance with CRMC 15.24.070, the building official or their designee shall obtain, review and reasonably utilize any base flood elevation and floodway data available from a federal, state or other source, in order to administer CRMC 15.24.260 through 15.24.310.

C. Information to Be Obtained and Maintained.

1. Where base flood elevation data is provided through the Flood Insurance Study or required as in subsection (B) of this section, obtain and record the actual (as-built) elevation (in relation to mean sea level) of the lowest floor, including basement, of all new or substantially improved structures, and whether or not the structure contains a basement.

2. Certification required by CRMC 15.24.310, Floodways. (44 CFR 60.3(d)(3))

3. Records of all variance actions, including justification for their issuance. (44 CFR 60.6(a)(6))

4. Improvement and damage calculations.

5. For all new or substantially improved floodproofed structures:

a. Verify and record the actual elevation (in relation to mean sea level); and

b. Maintain the floodproofing certifications required in CRMC 15.24.140(C).

6. Maintain for public inspection all records pertaining to the provisions of this chapter.

D. Alteration of Watercourses.

1. Notify adjacent communities and the Washington State Department of Ecology prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administration.

2. Require that maintenance is provided within the altered or relocated portion of said watercourse so that the flood-carrying capacity is not diminished.

E. Interpretation of FIRM Boundaries. Make interpretations, where needed, as to exact location of the boundaries of the areas of special flood hazards (for example, where there appears to be a conflict between a mapped boundary and actual field conditions). The person contesting the location of the boundary shall be given a reasonable opportunity to appeal the interpretation as provided in CRMC 15.24.170 through 15.24.190.

F. The floodplain administrator shall maintain a record of all variance actions, including justification for their issuance. [Ord. 2023-05, 2023; Ord. 88-14 § 4.3, 1988].

15.24.170 Variance procedure – Generally.

The variance procedure is as set out in CRMC 15.24.180 and 15.24.190.

A. In considering variance applications, the city of Castle Rock shall consider all technical evaluations, all relevant factors, all standards specified in other sections of this chapter, and:

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

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

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

4. The importance of the services provided by the proposed facility to the community;

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

6. The availability of alternative locations for the proposed use, which are not subject to flooding or erosion damage;

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

8. The relationship of the proposed use to the comprehensive plan and floodplain management program for that area;

9. The safety of access to the property in time of flood for ordinary and emergency vehicles;

10. The expected heights, velocity, duration, rate of rise, and sediment transport of the flood waters expected at the site; and

11. The costs of providing governmental services during and after flood conditions, including maintenance and repair of public utilities and facilities, such as sewer, gas, electrical, water system, and streets and bridges. [Ord. 2023-05, 2023; Ord. 88-14 § 4.4, 1988].

15.24.180 Appeal board.

A. The city council shall hear and decide appeals and requests for variances from the requirements of this chapter.

B. The city council shall hear and decide appeals when it is alleged there is an error in any requirement, decision or determination made by the building official or their designee in the enforcement or administration of this chapter.

C. Those aggrieved by the decision of the city council, or any taxpayer, may appeal such decision to the Cowlitz County superior court, as provided in RCW Title 34.

D. In passing upon such applications, the city council shall consider all technical evaluations, all relevant factors and standards specified in other sections of this chapter, and:

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

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

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

4. The importance of the services provided by the proposed facility to the community;

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

6. The availability of alternative locations for the proposed use which are not subject to flooding or erosion damage;

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

8. The relationship of the proposed use to the comprehensive plan and floodplain management program for that area;

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

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

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

E. Upon consideration of the factors of subsection (D) of this section and the purposes of this chapter, the city council may attach such conditions to the granting of variances as it deems necessary to further the purposes of this chapter.

F. The building official or their designee shall maintain the records of all appeal actions and report any variances to the Federal Emergency Management Administration upon request. [Ord. 2023-05, 2023; Ord. 2015-12 § 1, 2015; Ord. 88-14 § 4.4-1, 1988].

15.24.190 Conditions for variances.

A. Generally, the only condition under which a variance from the elevation standard may be issued is for new construction and substantial improvements to be erected on a lot of one-half acre or less in size contiguous to and surrounded by lots with existing structures constructed below the base flood level, providing CRMC 15.24.180(D)(1) through (11) have been fully considered. As the lot size increases, the technical justification required for issuing the variance increases.

B. Variances 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 this section.

C. Variances shall not be issued within a designated floodway if any increase in flood levels during the base flood discharge would result.

D. Variances shall only be issued upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.

E. Variances shall only be issued upon:

1. A showing of good and sufficient cause;

2. A determination that failure to grant the variance would result in exceptional hardship to the applicant;

3. A determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public as identified in CRMC 15.24.180(D), or conflict with existing local laws or ordinances.

4. Upon a showing that the use cannot perform its intended purpose unless it is located or carried out in close proximity to water. This includes only facilities defined in CRMC 15.24.050 in the definition of “Functionally dependent use.”

F. Variances as interpreted in the National Flood Insurance Program are based on the general zoning law principle that they pertain to a physical piece of property; they are not personal in nature and do not pertain to the structure, its inhabitants, economic or financial circumstances. They primarily address small lots in densely populated residential neighborhoods. As such, variances from the flood elevations should be quite rare.

G. Variances may be issued for nonresidential buildings in very limited circumstances to allow a lesser degree of floodproofing than watertight or dry-floodproofing, where it can be determined that such action will have low damage potential, complies with all other variance criteria except those set out in subsection (A) of this section, and otherwise complies with CRMC 15.24.210 and 15.24.220.

H. Any applicant to whom a variance 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, that the cost of flood insurance will be commensurate with the increased risk resulting from the reduced floor elevation, and that such construction below the base flood elevation increases risks to life and property. [Ord. 2023-05, 2023; Ord. 88-14 § 4.4-2, 1988].

Article V. Provisions for Flood Hazard Reduction

15.24.200 General standards.

A. In all areas of special flood hazards, the following standards set out in CRMC 15.24.210 through 15.24.250 are required.

B. General requirements for development in all areas of special flood hazards not set out in CRMC 15.24.210 through 15.24.250 are below:

1. All development, including manmade changes to improved or unimproved real estate for which specific provisions are not specified in this chapter or the state building codes with adopted amendments and any city of Castle Rock amendments, shall:

a. Be located and constructed to minimize flood damage;

b. Meet the encroachment limitations of this chapter if located in a regulatory floodway;

c. Be anchored to prevent flotation, collapse, or lateral movement resulting from hydrostatic loads, including the effects of buoyancy, during conditions of the design flood;

d. Be constructed of flood damage-resistant materials;

e. Meet the flood opening requirements of CRMC 15.24.270(B); and

f. Have mechanical, plumbing, and electrical systems above the design flood elevation or meet the requirements of ASCE 24, except that minimum electric service required to address life safety and electric code requirements is permitted below the design flood elevation provided it conforms to the provisions of the electrical part of building code for wet locations. [Ord. 2023-05, 2023; Ord. 88-14 § 5.1, 1988].

15.24.210 Anchoring.

A. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure.

B. All manufactured homes must likewise be anchored to prevent flotation, collapse or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors (reference FEMA P-85, Protecting Manufactured Homes from Floods and Other Hazards, for additional techniques). [Ord. 2015-12 § 1, 2015; Ord. 88-14 § 5.1-1, 1988].

15.24.220 Construction materials and methods.

A. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

B. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

C. Electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding. [Ord. 88-14 § 5.1-2, 1988].

15.24.230 Utilities.

A. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.

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

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

D. Water wells shall be located on high ground that is not in the floodway. [Ord. 2023-05, 2023; Ord. 88-14 § 5.1-3, 1988].

15.24.240 Subdivision proposals.

A. All subdivision proposals shall be consistent with the need to minimize flood damage.

B. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.

C. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.

D. Where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least 50 lots or five acres (whichever is less). [Ord. 88-14 § 5.1-4, 1988].

15.24.250 Review of building permits.

Where elevation data is not available either through the Flood Insurance Study or from another authoritative source (CRMC 15.24.160(B)), applications for building permits shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate at least two feet above grade in these zones may result in higher insurance rates. [Ord. 88-14 § 5.1-5, 1988].

15.24.260 Specific standards.

In all areas of special flood hazards where base flood elevation data has been provided as set forth in CRMC 15.24.070 and 15.24.160(B), the following provisions set out in CRMC 15.24.270 through 15.24.300 are required. [Ord. 88-14 § 5.2, 1988].

15.24.270 Residential construction.

A. In A zones where BFE has been determined or can be reasonably obtained new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot or more above base flood elevation. Mechanical equipment and utilities shall be waterproof or elevated at least one foot above the BFE.

B. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or 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 architect or must 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 or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.

4. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of flood waters.

C. New construction and substantial improvement of any residential structure in an Unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade. [Ord. 2023-05, 2023; Ord. 88-14 § 5.2-1, 1988].

15.24.280 Nonresidential construction.

New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated one foot or more above the level of the base flood elevation or elevated as required by ASCE 24, whichever is greater; or, together with attendant utility and sanitary facilities, shall:

A. Be floodproofed so that below one foot above the base flood level the structure is watertight with walls substantially impermeable to the passage of water;

B. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy;

C. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this section based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in CRMC 15.24.160(C)(2);

D. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in CRMC 15.24.270(B);

E. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the floodproofed level (e.g., a building floodproofed to one foot above the base flood level will be rated as at the base flood level). [Ord. 2023-05, 2023; Ord. 88-14 § 5.2-2, 1982].

15.24.290 Critical facility.

Construction of new critical facilities shall be, to the extent possible, located outside the limits of the base floodplain. Construction of new critical facilities shall be permissible within the base floodplain if no feasible alternative site is available. Critical facilities constructed within the base floodplain shall have the lowest floor elevated to three feet or more above the level of the base flood elevation at the site. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. Access routes elevated to or above the level of the base floodplain shall be provided to all critical facilities to the extent possible. [Ord. 88-14 § 5.2-3, 1988].

15.24.300 Manufactured homes.

All manufactured homes to be placed or substantially improved shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is one foot or more above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of CRMC 15.24.210(B). This section applies to manufactured homes to be placed or substantially improved in an expansion to an existing manufactured home park or subdivision. [Ord. 2023-05, 2023; Ord. 2015-12 § 1, 2015; Ord. 88-14 § 5.2-4, 1988].

15.24.305 Recreational vehicles.

Recreational vehicles placed on sites are required to either:

A. Be on the site for fewer than 90 consecutive days; or

B. Be fully licensed and ready for highway use, on wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

C. Meet the requirements of CRMC 15.24.300. [Ord. 2023-05, 2023].

15.24.307 Enclosed area below the lowest floor.

If buildings or manufactured homes are constructed or substantially improved with fully enclosed areas below the lowest floor, the areas shall be used solely for parking of vehicles, building access, or storage. [Ord. 2023-05, 2023].

15.24.309 AE and A1-30 zones with base flood elevation but no floodway.

In areas with BFEs (but a regulatory floodway has not been designated), no new construction, substantial improvements, or other development (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. [Ord. 2023-05, 2023].

15.24.310 Floodways.

Located within areas of special flood hazard established in CRMC 15.24.070 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 apply:

A. Prohibit encroachments, including fill, new construction, substantial improvements and other development unless certification by a registered professional engineer is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.

B. Construction or reconstruction of residential structures is prohibited within designated floodways, except for: (1) repairs, reconstruction or improvements to a structure which do not increase the ground floor area; and (2) repairs, reconstruction or improvements to a structure, the cost of which does not exceed 50 percent of the market value of the structure either (a) before the repair, reconstruction or repair is started, or (b) if the structure has been damaged, and is being restored, before the damage occurred. Work done on structures to comply with existing health, sanitary or safety codes or to structures identified as historic places shall not be included in the 50 percent determination.

C. If subsection (A) of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this article. [Ord. 2023-05, 2023; Ord. 88-14 § 5.3, 1988].

15.24.320 Wetlands management.

To the maximum extent possible, avoid the short- and long-term adverse impacts associated with the destruction or modification of wetlands, especially those activities which limit or disrupt the ability of the wetland to alleviate flooding impacts. The following process should be implemented:

A. Review proposals for development within base floodplains for their possible impacts on wetlands located within the floodplain.

B. Ensure that development activities in or around wetlands do not negatively affect public safety, health and welfare by disrupting the wetlands’ ability to reduce flood and storm drainage.

C. Request technical assistance from the Department of Ecology in identifying wetland areas. Existing wetland map information from the National Wetlands Inventory (NWI) can be used in conjunction with the community’s FIRM to prepare an overlay zone indicating critical wetland areas deserving special attention. [Ord. 88-14 § 5.4, 1988].

15.24.330 Standards for shallow flooding areas (AO zones).

Shallow flooding areas appear on FIRMs as AO zones with depth designations. The base flood depths in these zones range from one to three feet above ground where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In addition to other provisions in this code, the following additional provisions also apply in AO zones:

A. New construction and substantial improvements of residential structures and manufactured homes within AO zones shall have the lowest floor (including basement and mechanical equipment) elevated above the highest adjacent grade to the structure, one foot or more above the depth number specified in feet on the community’s FIRM (at least two feet above the highest adjacent grade to the structure if no depth number is specified).

B. New construction and substantial improvements of nonresidential structures within AO zones shall either:

1. Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, one foot or more above the depth number specified on the FIRM (at least two feet if no depth number is specified); or

2. Together with attendant utility and sanitary facilities, be completely flood proofed to or above that level so that any space below that level 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. If this method is used, compliance shall be certified by a registered professional engineer, or architect as in CRMC 15.24.280(C).

C. Require adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures.

D. Recreational vehicles placed on sites within AO zones on the community’s FIRM either:

1. Be on the site for fewer than 180 consecutive days; or

2. Be fully licensed and ready for highway use, 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; or

3. Meet the requirements of subsections (A) and (C) of this section and the anchoring requirements for manufactured homes in CRMC 15.24.300. [Ord. 2023-05, 2023].