Chapter 11.20
FLOOD DAMAGE PREVENTION

Sections:

11.20.010    Reserved.

11.20.020    Statement of purpose.

11.20.030    Definitions.

11.20.040    Lands to which this chapter applies.

11.20.050    Basis for establishing the areas of special flood hazard.

11.20.060    Establishment of development permit.

11.20.070    Designation of the Natural Resources Director.

11.20.080    Duties and responsibilities of the Natural Resources Director.

11.20.090    General standards for flood hazard reduction.

11.20.100    Specific standards for flood hazard reduction.

11.20.110    Zones with base flood elevations but no floodways.

11.20.120    Floodways.

11.20.010 Reserved.

11.20.020 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; and

H. To ensure that those who occupy the areas of special flood hazard assume responsibility for their actions. [Res. 2011-020; Res. 2006-63; Res. 1997-44. Prior code § 7.3.1.020.]

11.20.030 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.

“Area of special flood hazard” means the land in the floodplain within the community subject to a one percent or greater chance of flooding in any given year. Designation on maps always includes the letter “A” or “V.”

“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.” Designation on maps always includes the letter “A” or “V.”

“Development” means any man-made 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, or storage of equipment and materials located within the area of special flood hazard.

“Flood” or “flooding” means a general and temporary condition of partial or complete inundation of normally dry land areas from:

1. The overflow of inland or tidal waters; and/or

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

“Flood Insurance Rate Map (FIRM)” means the official map on which the Federal Insurance Administration has delineated both areas of special flood hazards and the risk premium zones applicable to the community.

“Flood Insurance Study” means the official report provided by the Federal Insurance Administration that includes flood profiles, the Flood Boundary-Floodway Map, and the water surface elevation of the base flood.

“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 one foot.

“Lowest floor” means the lowest floor of the lowest enclosed area, including basement. An unfinished or flood restraint 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 CTC 11.20.100(A)(2).

“Manufactured home” means a structure, transportable in one or more sections, that 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.

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

“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 a walled and roofed building including a gas or liquid storage tank that is principally above ground.

“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:

1. Before the improvement or repair is started; or

2. 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. [Res. 2017-2; Res. 2016-17; Res. 2011-020; Res. 2006-63; Res. 1997-44. Prior code § 7.3.2.010.]

11.20.040 Lands to which this chapter applies.

This chapter shall apply to all areas of special flood hazards within the jurisdiction of the Chehalis Tribe. [Res. 2016-17; Res. 2011-020; Res. 2006-63; Res. 1997-44. Prior code § 7.3.3.010.]

11.20.050 Basis for establishing the areas of special flood hazard.

The areas of special flood hazard identified in the Comprehensive Flood Hazard Management Plan (CFHMP) for the Confederated Tribes of the Chehalis Reservation, adopted by Resolution No. 2009-51 on April 28, 2009, and approved by the WA State Department of Ecology on April 20, 2009, and those identified in the Federal Insurance Administration in a scientific and engineering report entitled “The Flood Insurance Study for Grays Harbor County and Incorporated Areas” dated February 3, 2017 (Flood Insurance Study), and any revisions thereto, with an accompanying Flood Insurance Rate Map (FIRM), and any revisions thereto, are hereby adopted by reference and declared to be a part of this chapter. The CFHMP, the Flood Insurance Study, and the FIRM are on file at the Chehalis Tribal Planning Department, 420 Howanut Road, Oakville, Washington. In the event of a conflict between the data of the CFHMP and the Flood Insurance Study or FIRM, the more restrictive data shall be applied. [Res. 2017-2; Res. 2016-17; Res. 2011-020; Res. 2009-112; Res. 2006-63; Res. 1997-44. Prior code § 7.3.3.020.]

11.20.060 Establishment of development permit.

A. Development Permit Required. A development permit shall be obtained before construction or development begins within any area of special flood hazard established in CTC 11.20.050. The permit shall be for all structures including manufactured homes, as set forth in CTC 11.20.030 and for all development including fill and other activities, also as set forth in CTC 11.20.030. [Res. 2016-17; Res. 2011-020; Res. 2006-63; Res. 1997-44. Prior code § 7.3.4.010.]

11.20.070 Designation of the Natural Resources Director.

The Natural Resources Director is hereby appointed to administer and implement this chapter by granting or denying development permit applications in accordance with its provisions. [Res. 2011-020; Res. 2006-63; Res. 1997-44. Prior code § 7.3.4.020.]

11.20.080 Duties and responsibilities of the Natural Resources Director.

Duties of the Natural Resources Director 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 the proposed development is located in the floodway. If located in the floodway, ensure that the encroachment provisions of CTC 11.20.120 are met.

B. Use of Other Base Flood Data. When base flood elevation data has not been provided in accordance with CTC 11.20.050, the Natural Resources Director 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 CTC 11.20.100 and 11.20.120.

C. Information to Be Obtained and Maintained.

1. Where base flood elevation data is provided through the Flood Insurance Study or required as in CTC 11.20.080(B), obtain and record the actual 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. For all new or substantially improved flood-proofed structures:

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

b. Maintain the flood-proofing certifications required in CTC 11.20.100(A)(2) and (B)(3).

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

D. Alteration of Watercourses.

1. Notify adjacent communities and the Tribal Administrator 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 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. Such appeals shall be granted consistent with the standards of Section 60.6 of the rules and regulations of the National Flood Insurance Program (44 C.F.R. Sections 59 through 76). [Res. 2016-17; Res. 2011-020; Res. 2006-63; Res. 1997-44. Prior code § 7.3.4.030.]

11.20.090 General standards for flood hazard reduction.

In all areas of special flood hazard, the following standards are required:

A. Anchoring.

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

2. 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’s “Manufactured Home Installation in Flood Hazard Areas” guidebook for techniques).

B. Construction Materials and Methods.

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

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

3. 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.

C. Utilities.

1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system;

2. Water wells shall be located on high ground that is not in the floodway;

3. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharge from the systems into flood waters; and

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

D. Subdivision Proposals.

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

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

3. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and

4. 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 greater than 50 lots or five acres, whichever is less.

E. Review of Building Permits. Where elevation data is not available either through the Flood Insurance Study or from another authoritative source pursuant to CTC 11.20.080(B), applications for building permits shall be reviewed to ensure 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. [Res. 2017-2; Res. 2016-17; Res. 2011-020; Res. 2009-112; Res. 2006-63; Res. 1997-44. Prior code § 7.3.5.010.]

11.20.100 Specific standards for flood hazard reduction.

In all areas of special flood hazard where base flood elevation data has been provided as set forth in CTC 11.20.050 or CTC 11.20.080(B), the following provisions are required:

A. Residential Construction.

1. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated two feet or more above base flood elevation.

2. 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:

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 no higher than one foot above grade. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.

B. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated to the level of the base flood elevation; or, together with attendant utility and sanitary facilities, shall:

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

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

3. 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 subsection 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 CTC 11.20.080(C)(2);

4. Nonresidential structures that are elevated, flood-proofed, must meet the same standards for space below the lowest floor as described in subsection (A)(2) of this section;

5. Applicants flood-proofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot below the flood-proofed level (e.g., a building flood-proofed to the base flood level will be rated as one foot below).

C. Manufactured Homes.

1. All manufactured homes to be placed or substantially improved within Zones A1-A30, AH, and AE on the community’s FIRM on sites:

a. Outside of a manufactured home park or subdivision,

b. In a new manufactured home park or subdivision,

c. In an expansion to an existing manufactured home park or subdivision, or

d. In an existing manufactured home park or subdivision on which a manufactured home has incurred “substantial damage” as the result of a flood;

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

2. Manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within Zones Al-A30, AH, and AE on the community’s FIRM that are not subject to the above manufactured home provisions be elevated so that either:

a. The lowest floor of the manufactured home is elevated one foot above the base flood elevation, or

b. 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 designed foundation system to resist flotation, collapse, and lateral movement.

D. Recreational Vehicles. Recreational vehicles placed on sites are required to 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, be attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

3. Meet the requirements of subsection C of this section and the elevation and anchoring requirements for manufactured homes. [Res. 2016-17; Res. 2011-020; Res. 2009-112; Res. 2006-63; Res. 1997-44. Prior code § 7.3.5.020.]

11.20.110 Zones with base flood elevations but no floodways.

In areas with base flood elevations, but where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development, including fill, shall be permitted in Zones A1-A30 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 at any point within the community. [Res. 2016-17; Res. 2011-020; Res. 2009-112. Prior code § 7.3.5.030.]

11.20.120 Floodways.

Located within areas of special flood hazard established in CTC 11.20.050 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters that can carry debris, and increase erosion potential, the following provisions apply:

A. Encroachments, including fill, new construction, substantial improvements, and other development, are prohibited unless certification by a registered professional engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would 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 that 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 or reconstruction is started, or

b. If the structure has been damaged, and is being restored, before the damage occurred.

c. Any project for improvement of a structure to correct existing violations of local health, sanitary, or safety code specifications that have been identified by the local code enforcement official and that are the minimum necessary to assure safe living conditions, or to structures identified as historic places, may be excluded from the 50 percent.

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 CTC 11.20.090 through this section. [Res. 2016-17; Res. 2011-020; Res. 2009-112. Prior code § 7.3.5.040.]