Chapter 30.65
SPECIAL FLOOD HAZARD AREAS

Sections:

30.65.005    Repealed.

30.65.010    Purpose and applicability.

30.65.020    Intent.

30.65.030    National Flood Insurance Program.

30.65.040    Special flood hazard areas established.

30.65.050    Identification on official zoning maps.

30.65.100    Floodproofing: use of available data.

30.65.110    Floodproofing: general standards.

30.65.120    Floodproofing: specific standards.

30.65.125    General requirements for all crawlspace construction

30.65.130    Elevation and floodproofing certification.

30.65.140    Certification form.

30.65.150    Information to be obtained.

30.65.160    Certification responsibility.

30.65.200    Floodway fringe areas: permitted uses.

30.65.210    Floodway fringe areas: prohibited uses.

30.65.220    Floodways: permitted uses.

30.65.230    Floodways: prohibited uses.

30.65.240    Density fringe area.

30.65.250    Density fringe area: maximum allowable density.

30.65.255    Density fringe area: maximum allowable obstruction.

30.65.260    Density fringe area: exceptions to maximum allowable density and obstruction limitations.

30.65.265    Density fringe area: recording required when density and obstruction allowances are increased.

30.65.270    Density fringe area: general provisions.

30.65.280    Density fringe area: permitted uses.

30.65.285    Density fringe area: prohibited uses.

30.65.300    Continuation of nonconforming uses and structures.

30.65.310    Nonconforming uses.

30.65.320    Discontinuance.

30.65.330    Restoration.

30.65.340    Nonconforming structures.

30.65.005 SR 530 flood impact area.*

(Added by Amended Ord. 14-046, June 25, 2014, Eff date July 7, 2014; Amended by Amended Ord. 14-104, Dec. 17, 2014, Eff date Dec. 27, 2014; Amended by Ord. 15-043, June 24, 2015, Eff date June 27, 2015; Repealed by Ord. 15-043, June 24, 2015, Eff date December 27, 2015)

*Code reviser’s note: Amended Emergency Ordinance 14-046 added this section as SCC 30.65.050. It was editorially renumbered to avoid duplication of numbering.

30.65.010 Purpose and applicability.

The purpose of this chapter is to protect the public health, safety and welfare in those areas subject to periodic inundation due to flooding, and to minimize losses due to flood conditions in the specific areas subject to this chapter by utilizing the methods and provisions set forth herein. The regulations set forth herein shall apply to all development in special flood hazard areas as defined in this title within the jurisdiction of the county.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.020 Intent.

This chapter restricts uses and regulates structures to those that are consistent with the degree of flood hazard. The intent of this chapter is:

(1) To minimize loss of life and property by restricting uses and regulating development in special flood hazard areas;

(2) To alert the county assessor, appraisers, owners, potential buyers and lessees to the natural limitations of the flood plain;

(3) To meet the minimum requirement of the national flood insurance program; and

(4) To implement state and federal flood protection programs.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.030 National Flood Insurance Program.

This chapter incorporates the minimum flood plain management standards and regulations of the National Flood Insurance Program (NFIP). The enactment of this chapter is a necessary prerequisite for the county’s continued eligibility in the NFIP.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.040 Special flood hazard areas established.

The special flood hazard areas designated by the federal emergency management agency in a scientific and engineering report entitled "the flood insurance study for unincorporated Snohomish County", dated September 16, 2005, and with the flood insurance rate maps (FIRMS)* for Snohomish County, Washington and incorporated areas revised September 16, 2005, or as amended* and issued by FEMA on paper or digital format, together with the corresponding U.S. army corps of engineers river study maps, are adopted herein by reference and declared to be a part of this chapter and are hereby established as special flood hazard areas for the purposes of this chapter.

*Code Reviser Note: The text shown above in 30.65.040 in italic font was added by Amended Ord. 05-068 but was not indicated with addition marks.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005)

30.65.050 Identification on official zoning maps.

In order to assist the public in identifying those properties within special flood hazard areas, the geographic extent of the areas shall generally be depicted upon the county’s official zoning maps. Said depiction shall be provided for informational purposes only.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005)

30.65.100 Floodproofing: use of available data.

(1) In all special flood hazard areas where base flood elevation data has been provided in accordance with SCC 30.65.040, or where the county can reasonably utilize base flood elevation data available from federal, state or other sources, the specific flood hazard protection standards of SCC 30.65.120 and SCC 30.65.230 shall be required.

(2) In all special flood hazard areas where base flood elevation data has not been provided, the County shall review all development proposals in accordance with SCC 30.65.110 general standards and SCC 30.65.120 specific standards and shall require compliance with the standards of said sections as necessary to assure that development will be reasonably safe from flooding. The test of reasonableness shall include use of historic data, high water marks, photographs of past flooding, etc., where available.

(3) When a regulatory floodway for a stream has not been designated, the county may require that applicants for new construction and substantial improvements reasonably utilize the best available information from a federal, state, or other source to consider the cumulative effect of existing, proposed, and anticipated future development and determine that the increase in the water surface elevation of the base flood will not be more than one foot at any point in the community. Building and development near streams without a designated floodway shall comply with the requirements of 44 CFR 60.3(b)(3) and (4) and (C)(10) of the National Flood Insurance Program regulations.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 07-005, February 21, 2007, Eff date March 4, 2007)

30.65.110 Floodproofing: general standards.

The following regulations shall apply in all special flood hazard areas.

(1) Anchoring and construction techniques.

(a) All new construction and substantial improvements shall be:

(i) anchored to prevent flotation, collapse or lateral movement of the structure;

(ii) constructed using materials and utility equipment resistant to flood damage; and

(iii) constructed using methods and practices that minimize flood damage.

(b) All mobile homes shall be anchored to resist flotation, collapse, or lateral movement. Minimum anchoring requirements shall be those established by chapter 30.54A SCC.

(2) Utilities.

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

(b) 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

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

(3) Subdivision proposals. All subdivision, short subdivision, binding site plan, planned residential development, or rural cluster subdivision proposals shall:

(a) Be consistent with the need to minimize flood damage;

(b) Have roadways, public utilities, and other facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage;

(c) Have adequate drainage provided to reduce exposure to flood damage; and

(d) Include base flood elevation data.

(4) Watercourse alterations. The flood carrying capacity within altered or relocated portions of any watercourse shall be maintained. Prior to the approval of any alteration or relocation of a watercourse in riverine situations, the department shall notify adjacent communities and the State Department of Ecology, and submit evidence of such notification to FEMA of the proposed development.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.120 Floodproofing: specific standards.

In all special flood hazard areas where base elevation data has been provided as set forth in SCC 30.65.100, the following regulations shall apply, in addition to the general regulations of SCC 30.65.110:

(1) All electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are permanently affixed to a structure and which may be subject to floodwater damage shall be elevated a minimum of one foot above the base flood elevation or higher (unless within an approved watertight structure).

(2) Residential construction.

(a) New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation, except as provided in subsection (c) for residential accessory structures.

(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 except as provided in subsection (c) for residential accessory structures. 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:

(i) 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;

(ii) the bottom of all openings shall be no higher than one foot above the interior and exterior lowest grades;

(iii) openings may be equipped with screens, louvers, or other coverings or devices only if they permit the automatic entry and exit of floodwaters.

(c) New construction and substantial improvement of a residential accessory structure, including but not limited to storage buildings, detached garages, sheds, and small pole buildings, together with attendant utility and sanitary facilities may as an alternative to the provisions of SCC 30.65.120(1) and (2), be wet floodproofed in accordance with the following:

(i) The structure must have a low potential for structural flood damage and shall not exceed a maximum assessed value for the cost of construction of $25,000. The market value of construction shall be determined by the department in accordance with the valuation procedure utilized in conjunction with the setting of building permit fees;

(ii) Be designed and oriented to allow the free passage of floodwaters through the structure in a manner affording minimum flood damage;

(iii) Not be used for human habitation;

(iv) Include adequate hydrostatic flood openings;

(v) Use flood resistant materials below the base flood elevation;

(vi) Must offer minimum resistance to the flow of floodwater (must not be in the floodway);

(vii) Must be anchored to prevent flotation, collapse or lateral movement; and

(viii) Must have elevated all electrical, plumbing and heating equipment one foot above the base flood elevation.

(d) Wet floodproofing will trigger higher flood insurance premiums.

(3) Nonresidential construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation; or, together with attendant utility and sanitary facilities, shall:

(a) Be floodproofed so that any portion of a structure below a minimum of one foot elevation above base flood level 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; and

(c) Must also comply with SCC 30.65.120(2)(b).

(4) Agricultural construction. New construction and substantial improvement of any agricultural structure except farmhouses and farmhouse mobile homes which are regulated by SCC 30.65.120(2) above shall have the lowest floor, including basement, elevated a minimum of one foot above the base flood elevation; and meet the floodproofing requirements of SCC 30.65.120(3). In the alternative, new construction and substantial improvement of any agricultural structure shall, together with attendant utility and sanitary facilities:

(a) Have a low potential for structural flood damage; and shall not exceed a maximum assessed value for the cost of construction of $65,000. The market value of construction shall be determined by the department in accordance with the valuation procedure utilized in conjunction with the setting of building permit fees; and

(b) Be designed and oriented to allow the free passage of floodwaters through the structure in a manner affording minimum flood damage;

(c) Not be used for human habitation;

(d) Include adequate hydrostatic flood openings;

(e) Use flood resistant materials below the base flood elevations;

(f) Must offer minimum resistance to the flow of floodwater (i.e. must not be in the floodway);

(g) Must be anchored to prevent flotation, collapse or lateral movement;

(h) Must have elevated all electrical, plumbing and heating equipment one foot above the base flood elevations; and

(i) Be subject to higher flood insurance premiums associated with wet floodproofing.

(5) Mobile homes.

(a) Installation of mobile homes and substantial improvements to mobile homes shall be elevated on a permanent foundation and shall be securely anchored to an adequately anchored foundation system in accordance with SCC 30.65.110(1)(b) to resist flotation, collapse and lateral movement, and shall have the lowest floor elevated a minimum of one foot above the base flood elevation. *

(6) Critical facilities as defined in SCC 30.91C.360 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 flood waters. Access routes elevated to or above the level of the base flood plain shall be provided to all critical facilities to the extent possible.

(7) Recreational vehicles, when otherwise permitted by county code, shall

(a) Be on the site for fewer than 180 consecutive days; and

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

(c) Be limited in the floodways to day use only (dawn to dusk) during the flood season (October 1 through March 30) with the following exceptions:

(i.) Recreational vehicle use associated with a legally occupied dwelling to accommodate overnight guests for no more than a 21-day period;

(ii.) Temporary overnight use by farm workers on the farm where they are employed subject to SCC 30.22.130(19)(a) and (b) above; and

(iii.) Subject to SCC 30.22.120(7)(a) and (b), temporary overnight use in a mobile home park which has been in existence continuously since 1970 or before, that provides septic or sewer service, water and other utilities, and that has an RV flood evacuation plan that has been approved and is on file with the Department of Emergency Management and Department of Planning and Development Services.

(8) When fill is permitted to be used as an elevation/floodproofing technique, it shall be designed and installed so that it is properly compacted, sloped and armored to resist potential flood velocities, scouring and erosion during flooding.

(9) Flood hazard permits issued for wet floodproofing of any structure or for elevated structures having enclosures below the elevated structure that are wet floodproofed shall be subject to a standard permit condition prohibiting human habitation. The conditions shall be recorded on title on a form approved by the department.

* Code Reviser Note: Amended Ordinance No. 07-005 deleted 30.65.120(5)(b) in its entirety but failed to show the following text of SCC 30.65.120(5)(b)(iii) as stricken: "(A) lots large enough to permit steps, (B) piling foundations placed in stable soil no more than 10 feet apart, and (C) reinforcement provided for pilings extending more than six feet above the ground level". This material has been omitted pursuant to SCC 1.02.020(2)(g).

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005; Amended Ord. 07-005, February 21, 2007, Eff date March 4, 2007)

30.65.125 General requirements for all crawlspace construction

(1) Crawlspace may be used to elevate a building in a special flood hazard area to or above the base flood elevation if the space is designed to meet the following National Flood Insurance Program requirements, which apply to all crawlspaces that have enclosed areas or floors below the base flood elevation:

(a) The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Hydrostatic loads and the effects of buoyancy can usually be addressed through the required openings discussed in SCC 30.65.125(b) below.

(b) The crawlspace is an enclosed area below the base flood elevation and, as such, must have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. The bottom of each flood vent opening can be no more than 1 foot above the lowest adjacent interior and exterior grade. Crawlspace construction is not permitted in FEMA coastal high hazard area designated V zones. Open pile or column foundations that withstand storm surge and wave forces are required in V zones.

(c) Portions of the building below the base flood elevation must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawlspace used to elevate the building, but also any joists, insulation, or other materials that extend below the base flood elevations. The recommended construction practice is to elevate the bottom of joists and all insulation above base flood elevation. Insulation is not a flood-resistant material. When insulation becomes saturated with floodwater, the additional weight often pulls it away from the joists and flooring. Ductwork or other utility systems located below the insulation may also pull away from their supports.

(d) Any building utility systems including ductwork within the crawlspace must be elevated above base flood elevation or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. Ductwork must either be placed one foot above the base flood elevation or sealed from floodwaters.

(Added Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005; Amended Ord. 07-005, Eff date March 4, 2007)

30.65.130 Elevation and floodproofing certification.

Certification shall be provided to verify that the minimum floodproofing and elevation standards of SCC 30.65.110 and 30.65.120 flood hazard protection standards have been satisfied. Certification shall be required only for the new construction or substantial improvement of any residential, commercial, industrial or non-residential structure located in a special flood hazard area, except that agricultural structures constructed in accordance with the wet floodproofing standards of SCC 30.65.120 (4) (a), (b) and (c) shall not require certification. A completed FEMA elevation certificate form 81-31 shall be required in accordance with National Flood Insurance Program regulations and standards.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005)

30.65.140 Certification form.

The form of the elevation and floodproofing certificate shall be specified by the department and shall be generally consistent with that required by FEMA for the administration of the national flood insurance program.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.150 Information to be obtained.

Surveyed existing ground elevations of the four corners of the proposed development shall be submitted with the plan review application. The elevation or floodproofing certificates shall verify the following flood hazard protection information:

(1) Surveyed existing ground elevations of the four corners of the proposed development; and

(2) 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; and

(3) The actual elevation (in relation to mean sea level) of floodproofing of all new or substantially improved floodproofed structures, and that the floodproofing measures utilized below the base flood elevation render the structure watertight with walls substantially impermeable to the passage of water and have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 07-005, February 21, 2007, Eff date March 4, 2007)

30.65.160 Certification responsibility.

The project proponent shall be responsible for providing required certification data to the department prior to the applicable construction inspections specified in the certification form. All elevation data specified in SCC 30.65.150 must be obtained and certified by a registered professional land surveyor. Other floodproofing data specified in SCC 30.65.150 must be obtained and certified by a registered professional engineer or architect. The elevation and floodproofing certification shall be permanently maintained by the department.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005)

30.65.200 Floodway fringe areas: permitted uses.

The following uses are permitted in the floodway fringe areas:

(1) Any use permitted by the applicable zone in accordance with chapter 30.22 SCC when in compliance with all applicable provisions established in this chapter unless prohibited by SCC 30.65.210.

(2) Utility transmission lines. Utility transmission lines shall be permitted when consistent with chapter 30.22 SCC and where not otherwise inconsistent with this chapter. When the primary purpose of such a transmission line is to transfer bulk products or energy through a floodway fringe or special flood hazard area en route to another destination, as opposed to serving customers within a floodway fringe or special flood hazard area, such transmission line shall conform to the following:

(a) Electric transmission lines shall cross floodway fringe and special flood hazard areas by the most direct route feasible. When support towers must be located within floodway fringe or special flood hazard areas, they shall be placed to avoid high flood water velocity and/or depth areas, and shall be adequately flood proofed.

(b) Buried utility transmission lines transporting hazardous materials, including but not limited to crude and refined petroleum products and natural gas, shall be buried a minimum of four feet below the maximum scour of the waterway, as calculated on the basis of hydrologic analyses. Such burial depth shall be maintained within the floodway fringe or special flood hazard area to the maximum extent of potential channel migration as determined by hydrologic analyses. All such hydrologic analyses shall conform to requirements of SCC 30.65.220(6)(c).

(c) Beyond the maximum extent of potential channel migration, utility transmission lines transporting hazardous and non-hazardous materials shall be buried below existing natural and artificial drainage features. Burial depth in all agricultural areas requiring or potentially requiring subsurface drainage shall be a minimum of six feet as measured from ground surface to the top of the transmission line, or at other such depth as deemed necessary by on-site investigations performed by a qualified soils expert familiar with Snohomish County soils. Burial depth in all other agricultural and non-agricultural floodway fringe or special flood hazard areas shall be determined on the basis of accepted engineering practice and in consideration of soil conditions and the need to avoid conflict with agricultural tillage.

(d) All buried utility transmission lines shall achieve sufficient negative buoyancy so that any potential for flotation or upward migration is eliminated.

(e) Above ground utility transmission lines not including electric transmission lines shall only be allowed for the transportation of non-hazardous materials. In such cases, applicants must demonstrate that line placement will have no appreciable effect upon flood depth, velocity, or passage. Such lines shall be adequately protected from flood damage.

(f) Above ground utility transmission line appurtenant structures including valves, pumping stations, or other control facilities shall not be permitted in floodway fringe or special flood hazard areas except where no other alternative is available or in the event a floodway fringe or special flood hazard location is environmentally preferable. In such instances, above ground structures shall be located so that no appreciable effect upon flood depth, velocity or passage is created, and shall be adequately flood proofed.

(3) Critical facilities. Construction of new critical facilities shall be allowed only if no feasible alternative site is available outside of the flood hazard area.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.210 Floodway fringe areas: prohibited uses.

New mobile home parks and the expansion of existing mobile home parks shall be prohibited in floodway fringe areas.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.220 Floodways: permitted uses.

The following uses are allowed in the floodway when permitted by the applicable zone in accordance with chapter 30.22 SCC, provided the use is in compliance with the applicable general and specific floodproofing standards of SCC 30.65.110 and 30.65.120, and other applicable provisions of this chapter and will have a negligible effect upon the floodway in accordance with the floodway encroachment provisions of SCC 30.65.230(1):

(1) Agriculture;

(2) Forestry, including processing of forest products with portable equipment;

(3) Preserves and reservations;

(4) Park and recreational activities;

(5) Removal of rock, sand and gravel, when the applicant can provide clear and convincing evidence that such uses will not divert flood flows causing channel shift or erosion, accelerate or amplify the flooding of downstream flood hazard areas, increase the flooding threat to upstream flood hazard areas, or in any other way threaten public or private properties. When allowed, such removal shall comply with the provisions of chapter 30.31D SCC and the county shoreline management program;

(6) Utility transmission lines when allowed in underlying zones unless otherwise prohibited by this chapter. When the primary purpose of such a transmission line is to transfer bulk products or energy through a floodway en route to another destination, as opposed to serving customers within a floodway, such transmission lines shall conform to the following:

(a) All utility transmission lines shall cross floodways by the most direct route feasible as opposed to paralleling floodways;

(b) Electric transmission lines shall span the floodway with support towers located in flood fringe areas or beyond. Where floodway areas cannot be spanned due to excessive width, support towers shall be located to avoid high flood water velocity and/or depth areas, and shall be adequately floodproofed;

(c) Buried utility transmission lines transporting hazardous materials, including but not limited to crude and refined petroleum products and natural gas, shall be buried a minimum of four feet below the maximum established scour of the waterway, as calculated on the basis of hydrologic analyses. Such burial depth shall be maintained horizontally within the hydraulic floodway to the maximum extent of potential channel migration as determined by hydrologic analyses. In the event potential channel migration extends beyond the hydraulic floodway, conditions imposed upon floodway fringe and special flood hazard areas shall also govern placement. All hydrologic analyses are subject to acceptance by the county, shall assume the conditions of a 100-year frequency flood as verified by the U.S. Army Corps of Engineers, and shall include on-site investigations and consideration of historical meander characteristics in addition to other pertinent facts and data. The use of riprap as a meander containment mechanism within the hydraulic floodway shall be consistent with the county shoreline management program;

(d) Buried utility transmission lines transporting non-hazardous materials including water and sewage shall be buried a minimum of four feet below the maximum established scour of the waterway as calculated on the basis of hydrologic analyses. Such burial depth shall be maintained horizontally within the hydraulic floodway to the maximum extent of potential channel migration as determined by hydrologic analyses. All hydrologic analyses shall conform to requirements in SCC 30.65.220(6)(c). The use of riprap as a meander containment mechanism within the hydraulic floodway shall be consistent with the county shoreline management program;

(e) Beyond the maximum extent of potential channel migration, utility transmission lines transporting hazardous and non-hazardous materials shall be buried below existing natural and artificial drainage features. Burial depth in all agricultural areas requiring or potentially requiring subsurface drainage shall be a minimum of six feet as measured from ground surface to the top of the transmission line, or at other such depth as deemed necessary by on-site investigations performed by a qualified soils expert familiar with county soils. Burial depth in all other agricultural and non-agricultural floodway areas shall be determined on the basis of accepted engineering practice and in consideration of soil conditions and the need to avoid conflict with agricultural tillage;

(f) All buried utility transmission lines shall achieve sufficient negative buoyancy so that any potential for flotation or upward migration is eliminated;

(g) Above ground utility transmission lines, not including electric transmission lines, shall only be allowed for the transportation of non-hazardous materials where an existing or new bridge or other structure is available and capable of supporting the line. When located on existing or new bridges or other structures with elevations below the level of the 100-year flood, the transmission line shall be placed on the down-stream side and protected from flood debris. In such instances, site specific conditions and flood damage potential shall dictate placement, design and protection throughout the floodway. Applicants must demonstrate that such above ground lines will have no appreciable effect upon flood depth, velocity or passage, and shall be adequately protected from flood damage. If the transmission line is to be buried except at the waterway crossing, burial specifications shall be determined as in SCC 30.65.220(6)(d).

(h) All floodway crossings by utility transmission lines transporting hazardous materials shall be equipped with valves capable of blocking flow within the pipeline in the event of leakage or rupture. All floodway crossings shall have valves unless otherwise indicated by standard engineering review of the site and type of transmission line as acceptable to the county with locations determined by other provisions of this chapter;

(i) Above ground utility transmission line appurtenant structures including valves, pumping stations, or other control facilities shall not be permitted in the floodway; and

(j) Where a floodway has not been determined by preliminary Corps of Engineers’ investigations or official designation, a floodway shall be defined by qualified engineering work by the applicant on the basis of a verified 100-year flood event;

(7) Repairs, reconstruction, replacement, or improvements to existing farmhouse structures which are located on lands designated as agricultural lands of long-term commercial significance under RCW 36.70A.170, subject to the following:

(a) The new farmhouse is a replacement for an existing farmhouse on the same farm site;

(b) There is no potential building site for a replacement farmhouse on the same farm outside the designated floodway;

(c) The farmhouse being replaced shall be removed, in its entirety, including foundation, from the floodway within 90 days after occupancy of the new farmhouse;

(d) For substantial improvements, and replacement farmhouses, the elevation of the lowest floor of the improvement and farmhouse respectively, including basement, is one foot higher than the base flood elevation;

(e) New and replacement water supply systems, are designed to eliminate or minimize infiltration of flood waters into the system;

(f) New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of flood waters into the system and discharge from the system into the flood waters;

(g) All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage;

(h) The replacement farmhouse shall not exceed the total square footage of encroachment of the structure which it is replacing.

(8) Replacement of single family dwellings, other than farmhouse replacement pursuant to SCC 30.65.220(7), when the flood depth, flood velocity, and flood-related erosion of the site is evaluated in order to identify a building location that offers the least risk of harm to life and property. A suitable building location for a replacement structure shall be approved for structures damaged by flooding or flood-related erosion only when the following are met:

(a) The State Department of Ecology, pursuant to RCW 86.16.041(4) and (5), assesses the risk of harm to life and property posed by the specific conditions of the floodway at any proposed building site, and based upon scientific analysis of depth, velocity, and flood-related erosion recommends to the county that a waiver to the floodway prohibition of RCW 86.16.041(2)(a) for repair, replacement or relocation of such structures is authorized for a specific building location.

(b) Repair, replacement or relocation of such structures is permitted only when authorization required pursuant to 30.65.220(8)(a) is given in writing by the state department of ecology pursuant to RCW 86.16.041(4) and (5).

(9) Repair, reconstruction, or improvement of residential structures, where repair, reconstruction, or improvement of a structure does not increase the ground floor area, and is not a substantial improvement.

(10) Water-dependent utilities and other installations which by their very nature must be in the floodway. Examples of such uses are: Dams for domestic/industrial water supply, flood control and/or hydroelectric production; water diversion structures and facilities for water supply, irrigation and/or fisheries enhancement; flood water and drainage pumping plants and facilities; hydroelectric generating facilities and appurtenant structures; structural and nonstructural flood damage reduction facilities, and stream bank stabilization structures and practices. The applicant shall supply convincing evidence that a floodway location is necessary in view of the objectives of the proposal and that the proposal is consistent with other provisions of this chapter and the county shoreline management program. In all instances of locating utilities and other installations in floodway locations, project design must incorporate floodproofing.

(11) Dikes, when the applicant can provide clear and convincing evidence that:

(a) Adverse effects upon adjacent properties will not result relative to increased floodwater depths and velocities during the base flood or other more frequent flood occurrences;

(b) Natural drainage ways are minimally affected in that their ability to adequately drain floodwaters after a flooding event is not impaired; and

(c) The proposal has been coordinated through the appropriate diking district where applicable, and that potential adverse effects upon other affected diking districts have been documented.

(12) Public works, limited to roads and bridges.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended by Amended Ord. 12-025, June 6, 2012, Eff date July 27, 2012)

30.65.230 Floodways: prohibited uses.

(1) The following uses/development are prohibited in the floodway:

(a) Any structure, including mobile homes designed for, or to be used for, human habitation of a permanent nature (including temporary dwellings authorized by SCC 30.22.130 except as provided by SCC 30.65.220(7), (8), and (9).

(b) All encroachments, including fill, new construction, and other development unless verification by a registered professional engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the effect of the subject encroachment together with the cumulative effects of all similar potential encroachments shall not materially cause water to be diverted from the established floodway, cause erosion, obstruct the natural flow of water, reduce the carrying capacity of the floodway, or result in any increase in flood levels during the occurrence of the base flood discharge.

(c) The construction or storage of any object subject to flotation or movement during flood level periods;

(d) The following uses, due to their high degree of incompatibility with the purpose of establishing and maintaining a functional floodway are specifically prohibited:

(i) the filling of marshlands,

(ii) solid waste landfills, dumps, junkyards, outdoor storage of vehicles and/or materials,

(iii) damming or relocation of any watercourse that will result in any downstream increase in flood levels during the occurrence of the base flood discharge; and

(iv) critical facilities as defined in this title.

(2) The listing of prohibited uses in this section shall not be construed to alter the general rule of statutory construction that any use not permitted is prohibited.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 07-005, February, 21, 2007, Eff date March 4, 2007)

30.65.240 Density fringe area.

(1) SCC 30.65.240 through 30.65.285 provide specific criteria to be used in regulating development in areas of high flood damage potential where conventional floodway areas cannot be established. In order to foster the continued agricultural use of prime farmlands in these flood plain areas, and maintain an acceptable level of flood hazard protection, the development criteria outlined by this chapter shall apply to all development in the density fringe area. The development criteria contained in SCC 30.65.250 and 30.65.255 shall be utilized to prevent a cumulative increase in the base flood elevation of more than one foot.

(2) The density fringe area shall consist of the following:

(a) Areas designated on the Floor Insurance Study (FIS) for Snohomish County and Incorporated Areas, and the Flood Insurance Rate Maps (FIRMS)* dated September 16, 2005, and as amended in paper or digital format.

(b) Stillaguamish River special flood hazard area (100-year flood plain) located between the mouth of said river and river mile 11.1; also corresponding to the Corps of Engineers study E-2-10-138 as modified by Snohomish County, sheets 1 through 8 or FIRMS as amended in paper or digital format by FEMA.

*Code Reviser Note: The text shown above in subsection (2)(a) in italic font was added by Amended Ord. 05-068 but was not indicated with addition marks.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005)

30.65.250 Density fringe area: maximum allowable density.

The land area occupied by any use or development permitted by this chapter that will displace floodwaters shall not exceed two percent of the land area of that portion of the lot located in the density fringe area. The limitations of this section shall not apply to those uses listed in SCC 30.65.260.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.255 Density fringe area: maximum allowable obstruction.

The maximum width (sum of widths) of all new construction, substantial improvements or other development shall not exceed 15 percent of the length of a line drawn perpendicular to the known floodwater flow direction at the point where the development(s) is located. The length of said line shall not extend beyond the property boundary or the edge of the density fringe area, whichever is less. The limitations of this section shall not apply to those uses listed in SCC 30.65.260.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.260 Density fringe area: exceptions to maximum allowable density and obstruction limitations.

The following uses shall be exempt from the maximum allowable density and obstruction limitations of SCC 30.65.250 and 30.65.255:

(1) Water-dependent utilities;

(2) Dikes;

(3) Utility facilities; and

(4) Public works, when the project proponent demonstrates that the floodwater displacement effects of the proposal when considered together with the maximum potential floodwater displacement allowed by SCC 30.65.250 and 30.65.255 shall not cause a cumulative increase in the base flood elevation of more than one foot. Floodwater displacement information shall be obtained and certified by a professional engineer.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.265 Density fringe area: recording required when density and obstruction allowances are increased.

When the density and/or the allowable obstruction area in a density fringe designation is increased pursuant to SCC 30.65.250 and 30.65.255, the property owner shall record with the Auditor’s office a notice in a form approved by Planning and Development Services describing the related flood hazard permit number, subject property assessor number(s) and structures included in the density fringe area calculations.

(Added Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005; Amended Ord. 07-005, Feb. 21, 2007, Eff date March 4, 2007)

30.65.270 Density fringe area: general provisions.

The following regulations shall apply to all development in the density fringe area:

(1) Identified natural drainage channels that are secondary to the river channel(s) in discharging floodwaters downstream during flood periods shall be preserved or maintained as open space.

(2) All structures and development shall be oriented parallel to known floodwater flow directions in order to minimize flow obstruction. Determination of such orientation shall be based upon topographical and historical flood data. When such information is not available, orientation shall be in an upstream-downstream direction, parallel with the adjacent river channel except that such orientation shall not be required for utility transmission lines permitted by SCC 30.65.280(6), and roads permitted by SCC 30.65.280(13).

(3) All new construction and substantial improvements shall comply with the flood hazard protection standards of SCC 30.65.120.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.280 Density fringe area: permitted uses.

The following uses are permitted in the density fringe area:

(1) Agriculture, including:

(a) Accessory agricultural structures such as but not limited to barns, milking parlors, silos, manure tanks, and loafing sheds that provide direct support for primary agricultural activities including tilling of the soil, raising of crops, horticulture, viticulture, small livestock, poultry, pasturing, grazing, dairying and/or animal husbandry; and

(b) Livestock protection mounds, when the mounds do not consist of solid waste as defined by this title; and

(c) Manure pits and lagoons;

(2) Forestry, including processing of forest products with portable equipment;

(3) Preserves and reservations;

(4) Parks and recreational activities;

(5) Removal of rock, sand and gravel providing that the applicant can provide clear and convincing evidence that such a use will not divert flood flows causing channel shift or erosion, accelerate or amplify the flooding of downstream flood hazard areas, increase the flood threat to upstream flood hazard areas, or in any other way threaten public or private properties. When allowed, such removal shall comply with the provisions of chapter 30.31D SCC and the county shoreline management program;

(6) Utility transmission lines, under the same terms and conditions of SCC 30.65.200(2);

(7) Water-dependent utilities. Examples of such uses are dams for domestic/industrial water supply, flood control and/or hydroelectric production; water diversion structures and facilities for water supply, irrigation and/or fisheries enhancement; flood water and drainage pumping plants and facilities; hydroelectric generating facilities and appurtenant structures; and structural and non-structural flood damage reduction facilities, and stream bank stabilization structures and practices;

(8) Improvements to existing residential structures that do not exceed the maximum allowable density and obstruction requirements of SCC 30.65.250 and 30.65.255;

(9) Single family farmhouse structures including modular homes and mobile homes placed on permanent concrete foundations, if the following conditions are met:

(a) The structure is constructed to building code standards;

(b) The farmhouse is necessary to the operation of a commercial farm engaged in agriculture;

(c) A potential building site for the farmhouse on the same farm site is not available outside the density fringe area;

(d) Earthfill utilized for building foundation shall be emplaced and stabilized in a manner that will prevent erosion from flood water flow;

(e) New and replacement water supply systems are designed to eliminate or minimize infiltration of flood waters into the system;

(f) New and replacement sanitary sewerage systems are designed and located to eliminate or minimize infiltration of flood waters into the system and to eliminate or minimize discharge from the system into the flood waters;

(g) All other utilities and connections to public utilities are designed, constructed, and located to eliminate or minimize flood damage;

(h) An egress plan for vacating the structure during the base flood occurrence shall be provided;

(10) Marinas;

(11) Dikes, if the applicant can provide clear and convincing evidence that:

(a) Adverse effects upon adjacent properties will not result relative to increased floodwater depths and velocities during the base flood or other more frequent flood occurrences;

(b) Natural drainage ways are minimally affected in that their ability to adequately drain floodwaters after a flooding event is not impaired; and

(c) The proposal has been coordinated through the appropriate diking district where applicable, and that potential adverse effects upon other affected diking districts have been documented;

(12) Utility facilities;

(13) Public works, limited to:

(a) Roads,

(b) Bridges,

(c) Docks, and

(d) Port facilities; and

(14) In urban growth areas only, sawmill storage yards when located adjacent to existing sawmill uses.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003; Amended Ord. 05-068, Sept. 7, 2005, Eff date Sept. 24, 2005; Amended by Amended Ord. 12-025, June 6, 2012, Eff date July 27, 2012)

30.65.285 Density fringe area: prohibited uses.

The following uses shall be prohibited in the density fringe area:

(1) Any structure, including mobile homes, designed for, or to be used for human habitation of a permanent nature (including temporary dwellings authorized by SCC 30.22.130, except as provided by SCC 30.65.280(8) and (9);

(2) The construction or storage of any object subject to flotation or movement during flooding;

(3) The filling of marshlands;

(4) Solid waste landfills, dumps, junkyards, outdoor storage of vehicles and/or materials;

(5) Damming or relocation on any watercourse that will result in any downstream increase in flood levels during the base flood;

(6) Critical facilities;

(7) The listing of prohibited uses in this section shall not be construed to alter the general rule of statutory construction that any use not permitted is prohibited.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.300 Continuation of nonconforming uses and structures.

Any nonconforming use or nonconforming structure may be continued subject to the provisions of this chapter. The provisions of SCC 30.65.310 through 30.65.340 shall be applied in place of other provisions in chapter 30.28 SCC relating to nonconforming uses and structures.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.310 Nonconforming uses.

Nonconforming uses shall not be expanded and may be changed only to other uses which are allowed by this chapter; except that nonsubstantial improvements to the structural portions of nonconforming uses are allowed as provided in SCC 30.65.330 (1).

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.320 Discontinuance.

If the nonconforming use is discontinued for a period of 12 consecutive months or more, the nonconforming status of the use is terminated and any future use of the land or structures shall be in conformity with the provisions of this chapter. The mere presence of a structure, equipment, or material shall not be deemed to constitute the continuance of a nonconforming use unless the structure, equipment or material is actually being occupied or employed in maintaining such use.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.330 Restoration.

(1) Nothing in this shall be deemed to prohibit the restoration of the structural portions of a nonconforming use located outside a designated floodway within six months from the date of its accidental damage by fire, explosion, natural disaster, or act of public enemy; provided that the applicable elevation and/or floodproofing requirements of this title shall be adhered to if the structure is destroyed. A structure shall be considered to be destroyed if the restoration costs exceed 75 percent of the market value; provided further that restoration of nonresidential structures in the floodway shall be allowed when the applicable provisions of SCC 30.65.220 and 30.65.230 are met.

(2) Construction or reconstruction of the structural portions of a nonconforming use pursuant to this section in a special flood hazard area, whether new construction, substantial or nonsubstantial improvements, shall be subject to all applicable provisions of this chapter and chapter 30.43C.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)

30.65.340 Nonconforming structures.

(1) Nonconforming structures may be structurally altered or enlarged and nonconforming structures accidentally damaged or destroyed by fire, explosion, act of God, or act of public enemy may be reconstructed; provided that the degree of nonconformance shall not be increased and the applicable elevation and/or floodproofing requirements of this title shall be observed when proposed construction is a substantial improvement provided further that, construction in the floodway (nonsubstantial and substantial improvements) shall be subject to the limitations of SCC 30.65.220 and 30.65.230.

(2) Nonconforming structures that are also the structural portions of a nonconforming use shall also be subject to the provisions of SCC 30.65.330.

(Added Amended Ord. 02-064, December 9, 2002, Eff date February 1, 2003)