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. 88-14 § 5.1, 1988; Ord. 2023-05, 2023)
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. 88-14 § 5.1-1, 1988; Ord. 2015-12 § 1, 2015)
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)
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. 88-14 § 5.1-3, 1988; Ord. 2023-05, 2023)
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)
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)
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. 88-14 § 5.2-1, 1988; Ord. 2023-05, 2023)
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. 88-14 § 5.2-2, 1982; Ord. 2023-05, 2023)
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)
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. 88-14 § 5.2-4, 1988; Ord. 2015-12 § 1, 2015; Ord. 2023-05, 2023)
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)
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)
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)
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. 88-14 § 5.3, 1988; Ord. 2023-05, 2023)
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)
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)