Chapter 18.55
OVERLAY ZONES AND SPECIFIC AREA PLAN REGULATIONS
Sections:
18.55.030 Historic resource alteration and demolition.
18.55.040 Greenway (GW) special purpose district.
18.55.050 Safe harbor zone (SH).
18.55.070 Flood hazard management statutory authority, findings of fact, purpose, and methods.
18.55.010 Purpose.
Overlay zones contain supplemental land use requirements for specific areas of the City. These standards may modify the development standards established for certain uses in the same zoning district. [Ord. 987 § 1 (Exh. A), 2022.]
18.55.020 Applicability.
The standards of this chapter supplement the other requirements of this code. In addition, this part of the code specifically addresses various regulatory requirements. When standards and provisions for an overlay zone differ from that of the underlying district, the standard for overlay zone shall apply. [Ord. 987 § 1 (Exh. A), 2022.]
18.55.030 Historic resource alteration and demolition.
1. Purpose. The purpose of this section is to encourage the preservation of Harrisburg’s historic resources through the establishment of procedures to review and act upon applications for permits to alter or demolish those resources.
2. Harrisburg Register of Historic Resources. The provisions of this section apply to all resources which are listed as follows:
a. I.O.O.F. Hall, 190 Smith Street;
b. May and Sender Store – three-bay arcaded facade/rectangular (original portion);
d. 125 Smith Street;
d. Lasell House, 730 South 2nd Street;
e. E.F. Wyatt House, 353 Smith Street;
f. Enoch Hoult House, 895 South 6th Street;
g. Katherine Upmeyer House, 290 North 7th Street;
h. May and Senders Warehouse, 200 North 5th Street (two oldest buildings);
i. Hardware Store, 180 Smith Street;
j. Harrisburg Ferry Landing, riverbank between Kesling and Schooling Streets;
k. George McCart House, 395 South 2nd Street;
l. Moody Building, 206 – 222 South 3rd Street;
m. Hubbell Building, 146 South 3rd Street, 286 – 294 Smith Street;
n. Farmers and Merchants Bank, 203 Smith Street;
o. Ling-Hall House, 290 Fountain Street;
p. Abner Water/J.P. Schooling House, 205 South 4th Street and outbuilding;
q. Alfred Humphrey House, 265 North 7th Street;
r. W.L. Tyler House, 185 North 4th Street;
s. Thomas Sommerville House, 196 South 4th Street;
t. H.M. Roberts House, 130 North 7th Street;
u. Marshall Canter House, 305 South 4th Street;
v. Stephen Church House, 225 North 2nd Street.
3. Alteration and Demolition Permits Required. A permit is required for alteration or demolition of any resource listed on the Harrisburg register of historic resources.
a. “Alteration,” as governed by this section, means any addition to, removal of, or change in the exterior part of a historic resource but shall not include paint color.
b. Nothing in this section shall be construed to prevent the ordinary maintenance or repair of any exterior architectural feature that does not involve a change in design, material, or external appearance. Nor does this section prevent the construction, reconstruction, alteration, rehabilitation, restoration, demolition, or removal of any such feature when the City Planner determines that such emergency action is required for the public safety due to an unsafe or dangerous condition.
c. Exception. A permit is not required under this section for the alteration of a historic resource when the review of the proposed alteration is required by an agency of the State or Federal government.
4. Review Procedures. The review process before the Planning Commission shall be as follows:
a. A property owner or his authorized agent may initiate a request for alteration or demolition of a historic resource by filing an application with the City and paying the filing fee, in accordance with the provisions of HMC 19.10.040(1).
b. A public hearing shall be held in accordance with the notice provisions of HMC 19.10.040.
c. Notice shall also be mailed to the owner(s) of the affected property, the State Historic Preservation Office, and any person requesting notice of demolition or alteration of a historic resource.
d. The hearing shall be held no later than 55 days after the application is filed.
e. The Planning Commission may recess a hearing on a request for an alteration or demolition in order to obtain additional information, or to serve notice on other property owners or persons who it decides may be interested in the request. Upon recessing for this purpose, the Planning Commission shall announce a time, date, and place for resumption of the hearing.
f. Notification of the Planning Commission decision shall be in accordance with HMC 19.10.040.
g. The decision of the Planning Commission shall be based on the criteria established in subsections (7)(a) through (g) of this section.
5. Criteria for Demolition – Criteria for Review of Demolition Application. In reviewing an application for demolition, the Planning Commission shall consider:
a. The state of repair of the building and the economic feasibility of rehabilitation.
b. Hardship of the applicant.
c. The quantity and quality of other historic resources in the City comparable in terms of type and style.
6. Decision Action for Demolition Review.
a. The Planning Commission shall either:
(1) Allow immediate issuance of the demolition permit; or
(2) Require a delay in the issuance of the permit for up to 120 days. During this period, the City shall attempt to determine if public or private acquisition and preservation are feasible, or if other alternatives exist which could prevent the demolition of the resource.
b. In the case of approval of the permit, the Planning Commission shall recommend to the property owner that the City be allowed to take several photographs of the resource prior to demolition. Any photographs shall be kept on file at the City Recorder’s office.
7. Review Criteria for an Alteration Application. In reviewing an application to alter a historic building and to preserve the historical and architectural integrity of historical resources, and to provide for public safety, Planning Commission decisions shall be based on applicable State and local codes and ordinances related to building, fire and life safety, and the following criteria:
a. The removal or alteration of any historical marker or distinctive architectural features shall be avoided when possible.
b. Alterations that include materials or a design not in keeping with the historic appearance of the building or structure shall be discouraged.
c. Alterations that have taken place over the course of time are part of the history and development of the building or structure. These alterations may be significant in their own right and shall be preserved if possible and appropriate.
d. Distinctive stylistic features or examples of skilled craftsmanship should be treated carefully and retained whenever possible.
e. Deteriorated architectural features shall be repaired, rather than replaced, whenever possible.
f. If it is necessary to replace deteriorated architectural features, new materials should match, as closely as possible, in terms of composition, design, color and texture.
g. Repair or replacement of missing architectural features shall be based on accurate duplications of features substantiated by historic, physical or pictorial evidence rather than on availability or architectural elements from other buildings or structures. The design shall be compatible with the size, scale, and material of the historic building or structure and shall be compatible with the character of the neighborhood.
8. Decision Action for Alteration Review. The Planning Commission shall take one of the following actions:
a. Approve the request as submitted; or
b. Approve the request with modifications, conditions, or recommendations; or
c. Deny the request. [Ord. 987 § 1 (Exh. A), 2022.]
18.55.040 Greenway (GW) special purpose district.
1. Purpose. The purpose of the GW district is to provide development controls to protect, conserve, enhance, and maintain the natural, scenic, historical, agricultural, economic and recreational qualities of land along the Willamette River, known as the Willamette River Greenway.
2. Area of the GW District. All lands lying within the State Department of Transportation greenway boundaries shall be included in the GW district.
3. Definitions. Unless specifically defined below, words or phrases used in this district shall be interpreted to give them the same meaning as they have in this chapter, so as to give this document its most reasonable application:
“Change of use” means making a different use of the land or water than that which existed on December 6, 1975. It includes a change which requires construction, alterations of the land, water, or other areas outside of existing buildings or structures, and which substantially alters or affects the land or water.
a. Change of use does not include a change of use of a building or other structure which does not substantially alter or affect the land or water upon which it is situated. An existing open storage area shall be considered to be the same as a building.
b. The sale of property is not in itself considered to be a change of use.
c. Landscaping, construction of driveways, modifications of existing structures, or the construction or placement of such subsidiary structures or facilities as are usual and necessary to the use and enjoyment of existing improvements shall not be considered a change of use for the purposes of the GW zone.
“Intensification” means any additions which increase or expand the area or amount of an existing use, or the level of activity.
a. Remodeling of the exterior of a structure not excluded below is intensification when it will substantially alter the appearance of the structure.
b. Maintenance and repair usual and necessary for the continuance of an existing use is not an intensification of use.
c. Reasonable emergency procedures necessary for the safety or the protection of property are not an intensification of use.
d. Residential use of lands within the greenway includes the practices and activities customarily related to the use and enjoyment of one’s home. Landscaping, construction of driveways, modification of existing structures or construction or placement of such subsidiary structures or facilities adjacent to the residence as are usual and necessary to such use and enjoyment shall not be considered intensification for the purposes of this zone.
e. Seasonal increases in gravel operations shall not be considered an intensification of use.
“Water-dependent” means a use or activity which can be carried out only on, in, or adjacent to water areas because the use requires access to the water body for waterborne transportation, recreation, energy, production, or source of water.
“Water-related” means uses which are not directly dependent upon access to a water body, but which provide goods or services that are directly associated with water-dependent land or waterway use and which, if not located adjacent to water, would result in a public loss of the quality of goods or services offered.
4. Uses Permitted Outright. In the GW district, the following uses and their accessory uses are permitted outright:
a. Gravel removal from the bed of the Willamette River conducted under permit from the State of Oregon.
b. Customary dredging and channel maintenance conducted under permit from the State of Oregon.
c. Seasonal increases in gravel operations as provided under permit from the State of Oregon.
d. The placing by a public agency of signs, markers, aids, etc., to serve the public.
e. Activities to protect, conserve, enhance and maintain public recreational, scenic, historical and natural uses on public lands, except that new or substantial increases in level of development of existing public recreational, scenic, historical or natural uses on public lands shall require review as provided by this chapter.
f. Erosion control operations not requiring a permit from the Division of State Lands.
g. Agriculture, as defined in ORS 215.203(2).
h. Reasonable emergency procedures necessary for the safety or protection of property.
i. Maintenance and repair usual and necessary for the continuance of an existing use.
j. In conjunction with existing use of related adjacent land, landscaping, construction of driveways, modifications of existing structures or the construction or replacement of such subsidiary structures or facilities, except residences or guest houses, which are usual and necessary to the use and enjoyment of existing improvements, and which are accomplished in a manner compatible with this chapter.
k. The propagation of timber or the cutting of timber for public safety or personal noncommercial use, not requiring a permit in accordance with the Forest Practices Act.
l. Uses legally existing on the effective date of the ordinance codified in this chapter; provided, however, that any change or intensification of such use shall require review as provided by ordinance.
m. Except as necessary for water-dependent or water-related uses or facilities, residences, parking lots, spoil and dump sites, roads and highways, restaurants, businesses, factories, and RV parks are not generally considered dependent on or related to water location needs.
5. Conditional Uses Permitted. In the GW district, all uses provided for in the underlying zones which are not provided for as permitted uses in the GW district are permitted when authorized in accordance with this section and Chapter 18.45 HMC.
6. Use Management Considerations and Criteria. In reviewing an application for a greenway conditional use permit, compliance with the following considerations and criteria shall be determined:
a. Agricultural lands shall be preserved and maintained for farm use.
b. Significant fish and wildlife habitats shall be protected.
c. Areas of ecological, scientific, historical or archaeological significance shall be protected, preserved, restored, or enhanced to the maximum extent possible.
d. The quality of the air, water and land resources in and adjacent to the greenway shall be preserved in the development, change of use, or intensification of use of land within the greenway zone.
e. Areas of annual flooding, floodplains and wetlands shall be preserved in their natural state to the maximum possible extent to protect water retention, overflow, and other natural functions.
f. The natural vegetative fringe along the river shall be maintained to the maximum extent that is practicable in order to assure scenic quality, protection of wildlife, protection from erosion and screening of uses from the river.
g. The proposed development, change of use or intensification of use is compatible with existing uses on the site and the surrounding area.
h. Areas considered for development, change of use or intensification of use, which have erosion potential, shall be protected from loss by appropriate means which are compatible with the provisions of the greenway zone.
i. Extraction of aggregate deposits shall be conducted in a manner designed to minimize adverse effects on water quality, fish and wildlife, vegetation, bank stabilization, stream flow, visual quality, noise and safety and to guarantee necessary reclamation.
j. Any public recreational use or facility shall not substantially interfere with the established uses on adjoining property.
k. Maintenance of public safety and protection of public and private property, especially from vandalism and trespass, shall be provided to the maximum extent practicable.
l. A minimum building setback line from the ordinary high water line of the Willamette River will be specified that will minimize adverse impacts upon the scenic qualities of lands along the river, except for buildings and structures in conjunction with a water-related or water-dependent use.
m. Public access to and along the river shall be provided in conjunction with subdivision, commercial and industrial development, and public lands acquisition where appropriate. This access should be located and designed to minimize trespass and other adverse effects on adjoining property.
n. The development shall be directed away from the river to the greatest possible extent.
o. The development, change of use, or intensification of use shall provide the maximum possible landscaped area, open space, or vegetation between the activity and the river.
p. Significant natural and scenic areas, viewpoints, and vistas shall be preserved.
7. Notification. Notice requirements to be mailed to the Oregon Department of Parks and Recreation:
a. Notice requirements of Chapter 19.25 HMC for a conditional use in the GW district.
b. A copy of the permit application.
c. Notice of the decision.
8. Review Process. A public hearing shall be held for any application proposing intensification, change of use, or development along the river within the greenway. Notice of the public hearing shall be provided to adjoining property owners and any individual or group that has requested to be notified of such action. [Ord. 987 § 1 (Exh. A), 2022.]
18.55.050 Safe harbor zone (SH).
1. Purpose. The purpose of this zone is to protect and restore water bodies and their associated riparian areas, thereby protecting and restoring the hydrologic, ecological and land conservation functions these areas provide. Specifically, this zone is intended to protect habitat for fish and other aquatic life, protect habitat for wildlife, protect water quality for human uses and for aquatic life, control erosion and limit sedimentation, and reduce the effects of flooding.
This zone attempts to meet these goals by excluding structures from buffer areas around fish-bearing lakes, streams and associated wetlands, and by prohibiting vegetation removal or other alteration in those buffers.
For cases of hardship, this chapter provides a procedure to reduce the riparian buffer. Alteration of the riparian area in such cases shall be offset by appropriate restoration or mitigation, as stipulated in this zone.
2. Definitions.
“Building envelope” means the land area, outside of all required setbacks, which is available for construction of a primary structure on a particular property.
“Fish use” means inhabited at any time of the year by anadromous or game fish species or fish that are listed as threatened or endangered species under the Federal or State Endangered Species Act. Fish use is determined from Oregon Department of Forestry stream classification maps.
“Impervious surface” means any material which reduces and prevents absorption of storm water into previously undeveloped land.
“Lawn” means grass or similar materials maintained as a ground cover of less than six inches in height. For purposes of this definition, lawn is not considered native vegetation regardless of the species used.
“Mitigation” means taking one or more of the following actions listed in order of priority:
a. Avoiding the impact altogether by not taking a certain development action or parts of that action;
b. Minimizing impacts by limiting the degree or magnitude of the development action and its implementation;
c. Rectifying the impact by repairing, rehabilitating, or restoring the affected environment;
d. Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the development action by monitoring and taking appropriate corrective measures; or
e. Compensating for the impact by replacing or providing comparable substitute resources or environments.
“Net loss” means a permanent loss of habitat units or habitat value resulting from a development action despite mitigation measures having been taken.
“Nonconforming” means a structure or use that does not conform to the standards of this zone but has been in continuous existence from prior to the date of adoption of the ordinance codified in this chapter up to the present. Nonconforming uses are not considered violations and are generally allowed to continue, though expansion, reconstruction, or substantial improvement may be regulated.
“Off-site mitigation” means habitat mitigation measures undertaken in areas distant from a development action, and which are intended to benefit fish and wildlife populations other than those directly affected by that action.
“On-site mitigation” means habitat mitigation measures undertaken within or in proximity to areas affected by a development action, and which are intended to benefit fish and wildlife populations directly affected by that action.
“Riparian area” means the area adjacent to a river, lake, or stream, consisting of the area of transition from an aquatic ecosystem to a terrestrial ecosystem.
“Stream” means a channel such as a river or creek that carries flowing surface water, including perennial streams and intermittent streams with defined channels, and excluding manmade irrigation and drainage channels.
“Structure” means a building or other major improvement that is built, constructed or installed, not including minor improvements such as fences, utility poles, flagpoles, or irrigation system components that are not customarily regulated through zoning ordinances.
“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. 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.
“Top of bank” means the stage or elevation at which water overflows the natural banks of streams or other waters of the State and begins to inundate upland areas. In the absence of physical evidence, the two-year recurrence interval flood elevation may be used to approximate the bank full stage or delineate the top of bank.
3. Riparian Corridors. The inventory of riparian areas contained in the comprehensive plan specifies which streams and lakes are fish-bearing, and the stream size category. Based on the classification contained in this inventory, the following riparian corridors shall be established:
Along all fish-bearing lakes, and fish-bearing streams with average annual stream flow less than 1,000 cubic feet per second, the riparian corridor boundary shall be 50 feet from the top of bank, except as identified below:
a. Along all streams with average annual stream flow greater than 1,000 cubic feet per second, the riparian corridor boundary shall be 75 feet upland from the top of each bank.
b. Where the riparian corridor includes all or portions of a significant wetland as identified in the Goal 5 or Goal 17 elements of the comprehensive plan, the standard distance to the riparian corridor boundary shall be measured from and include the upland edge of the wetland.
c. Except as provided for in subsection (3)(b) of this section, the measurement of distance to the riparian corridor boundary shall be from the top of bank. The measurement shall be a slope distance.
(1) In areas where the top of each bank is not clearly defined, the riparian corridor boundary shall be measured from the ordinary high water level, or the line of nonaquatic vegetation, whichever is most landward.
(2) In areas where the predominant terrain consists of steep cliffs, the distance to the corridor boundary shall be measured as a horizontal distance until the top of the cliff is reached, and as a slope distance on from that point.
4. Activities Within the Riparian Area.
a. The permanent alteration of the riparian area by grading or by the placement of structures or impervious surfaces is prohibited, except for the following uses, provided they are designed to minimize intrusion into the riparian area and no other options or locations are feasible:
(1) Streets, roads, and paths;
(2) Drainage facilities, utilities, and irrigation pumps;
(3) Water-related and water-dependent use;
(4) Replacement of existing structures with structures in the same location that do not disturb additional riparian surface area. Structures or other nonconforming alterations existing fully or partially within the riparian area may be expanded provided the expansion does not occur within the riparian area;
(5) Substantial improvement of a nonconforming structure in the riparian area shall require compliance with the standards of this zone;
(6) Existing lawn within the riparian area may be maintained but not expanded within the riparian area. Development activities on the property shall not justify replacement of riparian area with lawn;
(7) Existing shoreline stabilization and flood control structures may be maintained.
(a) Any expansion of existing structures or development of new structures shall be evaluated by the City Engineer.
(b) Such alteration of the riparian area shall be approved only if less invasive or nonstructural methods will not adequately meet the stabilization or flood control needs; and
(8) Parks and related recreational activities.
b. Removal of riparian vegetation is prohibited, except for:
(1) Removal of nonnative vegetation and replacement with native plant species. The replacement vegetation shall cover, at a minimum, the area from which vegetation was removed, and shall maintain or exceed the density of the removed vegetation.
(2) Removal of vegetation necessary for the development of approved water-related or water-dependent uses. Vegetation removal shall be kept to the minimum necessary to allow the water-dependent or water-related use.
(3) Trees in danger of falling and thereby posing a hazard to life or property may be removed, following consultation and approval from the City. If no hazard will be created, the City may require these trees, once felled, to be left in place in the riparian area. Exceptions: The following activities are not required to meet the standard of this section:
(a) Commercial forest practices regulated by the Oregon Forest Practices Act;
(b) Normal and accepted practices regulated by the Oregon Forest Practices Act.
5. Alteration Requiring Mitigation.
a. Permanent alteration of the riparian area by placement of structures or impervious surfaces is allowed if a variance to the riparian setback is approved through the procedures of Chapter 19.40 HMC.
b. On streams having average annual stream flow exceeding 1,000 cubic feet per second and having a 75-foot riparian buffer established under this chapter, the riparian setback may be reduced as allowed under subsection (6) of this section.
(1) For purposes of implementing Goal 5, the goal is no net loss of protected resources.
(2) Correspondingly, for purposes of designing appropriate mitigation, sites should be considered at least in Habitat Category 2 (OAR 635-415-025), which strives for no net loss of habitat values.
c. On streams having average annual stream flow exceeding 1,000 cubic feet per second and having a 75-foot riparian buffer established under this zone, structures and impervious surfaces may be placed within the riparian setback under the following conditions:
(1) The removal of vegetation shall be limited to the minimum amount necessary to accommodate the use. Any vegetation removed in excess of this standard shall be nonnative species, and the proposal shall specify replacement of that vegetation with native species.
(2) The applicant shall provide sufficient information regarding the proposed development and potential impacts to riparian resources to allow the staff, in consultation with the ODFW, to determine whether the proposal will provide equal or better protection of riparian resources. This information includes, but is not necessarily limited to:
(a) A plot plan showing the top of the stream or water body bank;
(b) The extent of development within the riparian setback;
(c) Uses that will occur within the riparian setback and potential impacts (for example: chemical runoff, noise, etc.);
(d) The extent of vegetation removal proposed;
(e) Characteristics of the existing vegetation (types, density);
(f) Any proposed alterations of topography or drainage patterns;
(g) Existing uses on the property; and
(h) Any potential impacts they could have on riparian resources.
(3) In no case shall alterations occupy more than 50 percent of the width of the riparian area measured from the upland edge of the corridor.
(4) Approval of development activities within the riparian area shall be conditional, requiring compliance with the mitigation recommendations of the Oregon Department of Fish and Wildlife (ODFW), as per OAR 635-415, Fish and Wildlife Habitat Mitigation Policy.
6. Variance. A property owner may request a variance to the riparian setback in accordance with Chapter 19.40 HMC. In any decision concerning granting of a variance, the following criteria shall be considered:
a. The proposed development requires deviation from the riparian standards because of exceptional physical characteristics over which the owner has no control;
b. Strict adherence to the riparian setback and other applicable standards would effectively preclude a use of the parcel that could be reasonably expected to occur in the zone;
c. That the property owner would be precluded a substantial property right enjoyed by the majority of landowners in the vicinity;
d. The granting of the variance would not confer any special privilege upon the applicant; and
e. The variance would not violate a provision of law. [Ord. 987 § 1 (Exh. A), 2022.]
18.55.060 Wetland protection.
1. Local Wetland Protection and Wetland Notification.
a. This section is applicable to all wetlands within the City of Harrisburg, whether on the Local Wetlands Inventory (LWI) map or not.
b. Wetland review, as defined by this code, is applicable to development on parcels containing any wetland protection area.
c. Unless otherwise stated, the City shall apply the provisions of this section in conjunction and concurrently with the requirements of any other development permit being sought by an applicant. If no other permit is being sought, the City Planner shall serve as the approving authority.
2. Wetland Protection Area – Purpose. The purposes of applying a wetland protection area to locally significant wetlands identified on the City’s Local Wetlands Inventory are:
a. To implement the goals and policies of the City of Harrisburg comprehensive plan;
b. To protect the City’s wetland areas, thereby protecting the hydrologic and ecologic functions these areas provide for the community;
c. To protect water quality and natural hydrology, to control erosion and sedimentation, and to reduce the adverse effects of flooding;
d. To protect fish and wildlife habitats;
e. To protect the amenity values and educational opportunities of the City’s wetlands as community assets; and
f. To improve and promote coordination among local, State, and Federal agencies regarding development activities in and near wetlands.
3. Wetland Notification – Purpose. The City is required by State law to provide notice to the Department of State Lands when a development activity may impact any wetland identified on the Local Wetlands Inventory. The purpose of this State requirement is to achieve better implementation of State law and to inform property owners when State and Federal wetland laws apply to their property.
4. Wetland Protection Area Definitions. The following definitions shall apply in this chapter:
“City Planner” refers to the person in charge of land use activities and applications for the City, including that person’s designee, and may refer to the City Planning Commission where multiple permits are being sought as stated in subsection (1)(c) of this section.
“Delineation” means a determination of wetland presence that includes marking the wetland boundaries on the ground and/or on a detailed map prepared by professional land survey or similar accurate methods. A delineation is a precise map and documentation of actual wetland boundaries on a parcel, whereas wetland boundaries identified on a Local Wetlands Inventory boundary are approximated with an accuracy target of five meters (approximately 16.5 feet). (See OAR 141-90-005 et seq. for specifications for wetland delineation reports.)
“Determination” means a decision of the presence or absence of wetlands. A determination made in the office using existing available information including maps and aerial photography is an “off-site” determination and is considered advisory only. An “on-site” determination involves site-specific data collection consistent with the 1987 U.S. Army Corps of Engineers Wetlands Delineation Manual and Regional Supplements.
“Local Wetlands Inventory” or “LWI” means the map and report attached to the ordinance codified in this chapter and incorporated by reference as City of Harrisburg Local Wetlands Inventory, and any subsequent revisions as approved by the Oregon Department of State Lands, which identify the location of wetlands and probable wetlands. The LWI is a comprehensive survey and assessment of all wetlands over one-half acre in size within the urbanizing area. This includes both locally significant wetlands and wetlands that are not identified as locally significant. This also includes “probable wetlands,” which are areas noted during the course of the LWI field work that appear to meet, or do meet, wetland criteria but are small or of undetermined size, and are mapped as a point rather than a polygon on the LWI map.
Locally Significant Wetland. Wetlands are determined to be “locally significant wetlands” based on Oregon Administrative Rules for Identifying Significant Wetlands (OAR 141-86-300 through 141-86-350). If the assessed wetland unit provides “diverse” wildlife habitat, “intact” fish habitat, “intact” water quality function, or “intact” hydrologic control function, then the wetland is locally significant. Locally significant wetlands are identified on the City’s Local Wetlands Inventory as such. Locally significant wetlands also constitute the wetland protection area (unless otherwise indicated in this section).
“Oregon freshwater wetland assessment methodology” or “OFWAM” means a wetland function and quality assessment methodology developed by the Oregon Department of State Lands (DSL) to assess water quality, hydrologic control, fish habitat, and wildlife habitat.
“Wetland” means an area inundated or saturated by surface or ground water at a frequency and duration sufficient to support a prevalence of vegetation typically adapted for life in saturated soil conditions.
“Wetland professional” means a professional with a background in wetland science and knowledgeable of the process for conducting wetland delineations and determinations.
“Wetland protection area” means an area subject to the provisions of this chapter that consists of wetlands determined to be locally significant as shown on the LWI map, plus 20 feet around the boundary of the significant wetland. The locally significant wetland areas identified on the LWI map (dated November 11, 2010) are referred to as HA-2, HA-19, and HA-24.
“Wetlands not subject to Goal 5 protection” includes all State jurisdictional wetlands, mapped or not, that are subject to the State Removal-Fill Law administered by DSL. All wetlands are “potentially jurisdictional wetlands.” Wetlands on the LWI map which are not identified as locally significant are considered “other potentially jurisdictional wetlands.” These wetlands are not subject to wetland protection area standards in the City of Harrisburg, but, like all wetland areas, are subject to DSL notice/review and potentially subject to DSL and the U.S. Army Corps of Engineers permitting.
5. Prohibited Activities Within Wetland Protection Areas. Except as exempted or allowed in this code, the following activities are prohibited within a wetland protection area:
a. Placement of new structures or impervious surfaces.
b. Excavation, grading, fill, or removal of vegetation.
c. Expansion of areas of landscaping with nonnative species, such as a lawn or garden, into the wetland protection area.
d. Disposal or temporary storage of refuse, yard debris, or other material.
e. Any use not specifically allowed or exempted, or granted a variance, under this chapter.
6. Exempted Activities Within Wetland Protection Areas.
a. The following activities, and continuation and/or maintenance thereof, are exempted from all wetland protection area regulations; provided, that any applicable State or Federal permits are secured:
(1) Any use, except those identified as allowed uses under subsection (7) of this section, that was lawfully existing on the date of adoption of the ordinance codified in this chapter, August 23, 2022, may continue within a wetland protection area. Such use or development may continue at a similar level and manner as existed on the date of adoption of the ordinance codified in this chapter as per the standards for nonconforming uses and structures as stated in Chapter 18.25 HMC.
(2) The maintenance and alteration of preexisting ornamental landscaping so long as no additional native vegetation is disturbed. The provisions of this section shall not be affected by any change in ownership of properties containing a wetland protection area.
(3) Restoration and enhancement of native vegetation.
(4) Cutting and removal of trees which pose a hazard to life or property due to threat of falling.
(5) Cutting and removal of trees to establish and maintain defensible space for fire protection.
(6) Removal of nonnative vegetation.
(7) Maintenance and repair of existing utilities.
(8) Normal farm practices such as grazing, plowing, planting, cultivating, harvesting, and other practices under the review authority of Oregon Department of Agriculture.
b. The following activities are also exempted from wetland protection area regulations, but are subject to State or Federal permits:
(1) Maintenance of existing drainage ways, ditches, or other structures, to maintain flow at original design capacity and mitigate upstream flooding; provided, that management practices avoid sedimentation and impact to native vegetation, any spoils are placed in uplands, and any applicable State permits are obtained.
(2) Emergency stream bank stabilization to remedy immediate threats to life or property.
(3) Wetland restoration and enhancement activities.
7. Allowed Activities Within Wetland Protection Areas. The following activities and maintenance thereof are allowed within a wetland protection area upon City review and approval and provided any applicable State or Federal permits are secured:
a. Replacement of a permanent, legal, nonconforming structure in existence on the date of adoption of the ordinance codified in this chapter, August 23, 2022, with a structure on or within the prior building footprint, or expansion of the original building footprint if it does not further encroach into a wetland area and is in accordance with the provisions of subsection (9) of this section.
b. Installation of interpretive or educational displays and/or public pedestrian paths, as long as these do not present an obstruction that would increase flood velocity or intensity.
c. New fencing may be permitted by the City Planner where the applicant demonstrates that the following criteria are satisfied:
(1) The fencing does not affect the hydrology of the site;
(2) The fencing does not present an obstruction that would increase flood velocity or intensity;
(3) Fish habitat is not adversely affected by the fencing; and
(4) Applications for new fencing within a wetland protection area shall contain a scale drawing that clearly depicts the wetland area boundary on the wetland resource.
8. Submittal Requirements for Wetland Review.
a. Where wetland review is applicable, applicants shall submit the following materials (unless otherwise indicated):
(1) A scale drawing that clearly depicts any Local Wetlands Inventory (LWI) map wetland boundary within the subject parcel, all surface water sources, existing trees and vegetation, property boundaries, and proposed site alterations including proposed excavation, fill, structures, and paved areas.
(2) Written statement of compliance with approval criteria for any proposed allowed activities. Activities listed as “allowed” under subsection (7) of this section and which are acknowledged to occur within a wetland protection area require a written statement of compliance but do not require any “demonstration of avoidance.”
(3) Demonstration of Wetland Protection Area Avoidance. The placement of structures or impervious surfaces, vegetation removal or grading within the vicinity of any wetland protection area shall require demonstration that all impact to the wetland shall be avoided. Avoidance can be demonstrated by any one of the following:
(a) Keeping all development activity including vegetation removal and grading back 20 feet from the edge of the wetland boundary shown on the LWI map; or
(b) Submitting an off-site determination, conducted by DSL, that concludes the proposed activities will occur outside the wetland; or
(c) Submitting an on-site determination, conducted by a qualified wetland professional, that concludes the proposed activities will occur outside the wetland protection area; or
(d) Submitting a current wetland delineation (completed within the last five years), certified by the Department of State Lands (DSL), that shows the proposed activities will occur outside the wetland protection area.
b. Activities listed as “allowed,” above, and which are acknowledged to occur within a wetland protection area do not require any “demonstration of avoidance.”
9. Approval Criteria. In approving allowed activities under subsection (7) of this section, and/or ensuring compliance with subsection (5) of this section (prohibited activities), the City Planner shall base its decision on the following criteria in addition to the required criteria for any other permit or approval that is being sought:
a. Demonstration of avoidance of impacts to wetland protection area as outlined under subsection (8) of this section; or
b. The proposed project will not result in excavation or filling of a wetland or reduction of wetland area that has been identified as part of a wetland protection area, except as allowed in criteria outlined specifically under subsection (7) of this section.
10. Decision Process – Appeals.
a. The City Planner shall review the application and make findings of fact.
b. If the applicant is not satisfied with the decision of the City Planner, the applicant may file a written notice of appeal with the City Recorder within 10 days following the decision. The appeal will be to the Planning Commission unless the Planning Commission was the deciding authority, in which case the appeal will be to the City Council. There shall be an appeal fee as set by the City Council.
11. Variances.
a. The Planning Commission shall be the approving authority for applications for variances to the wetland protection area provisions. The procedures of Chapter 19.40 HMC shall be followed for approval of a variance except that the variance criteria of this section shall also apply.
b. Mapping Error Variances and Corrections. The City Planner may correct the location of the wetland protection overlay zone when the applicant has shown that a mapping error has occurred, and the error has been verified by the Department of State Lands (DSL). Delineations verified by DSL shall be used to automatically update and replace Local Wetlands Inventory (LWI) mapping. No formal variance application or plan amendment is needed for map corrections where approved delineations are provided.
c. Hardship Variances. The Planning Commission may grant a variance to the provisions of this section only when the variance criteria are met, and the following conditions exist:
(1) Through application of this section, the property has been rendered not buildable;
(2) The applicant has exhausted all other options available under this section to relieve the hardship;
(3) The variance is the minimum necessary to afford relief;
(4) All State and Federal permits required for authorization of wetland impacts are obtained;
(5) No permitted type of land use for the property with less impact on the wetland is feasible and reasonable;
(6) There is no feasible on-site alternative to the proposed activities, including but not necessarily limited to reduction in size, density or intensity, phasing of project implementation, change in timing of activities, revision of road and lot layout, and/or related site planning considerations, that would allow a reasonable economic use with less adverse impacts;
(7) The proposal utilizes to the maximum extent possible innovative construction, design, and development techniques, including pervious surfaces, which minimize to the greatest extent possible net loss of wetland functions and values; and
(8) The area of disturbance is limited to the area that has the least practical impact on the wetland functions and values.
d. Alternative Hardship Review. The following scenarios provide an exemption from the standards outlined in subsections (5) and (7) of this section:
(1) The subject property contains less than 3,000 square feet of contiguous area outside of the wetland protection area; or
(2) The subject property contains 30,000 square feet or more, and proposed site disturbance is no more than 10 percent of the total lot area; and
(3) The amount of allowable disturbance shall be that which will have the least practicable impact on the wetland area given the characteristics and context of the subject property and wetland area.
12. Notification and Coordination with State Agencies.
a. The City shall notify the Oregon Department of State Lands (DSL) in writing of all applications to the City for development activities, including development applications, building permits, and other development proposals, that occur in any wetland identified on the Local Wetlands Inventory (LWI) map.
b. When conducting a wetland review under this section, the City Planner shall consider advisory recommendations from the Oregon Department of Fish and Wildlife, when appropriate, regarding OAR 635-415, Fish and Wildlife Habitat Mitigation Policy.
13. Unauthorized Alterations and Enforcement. When a wetland has been altered in violation of this section, the penalty provisions of Chapter 18.35 HMC shall apply and be in addition to any State ordinances or regulations. [Ord. 987 § 1 (Exh. A), 2022.]
18.55.070 Flood hazard management statutory authority, findings of fact, purpose, and methods.
1. Statutory Authorization. The State of Oregon has in ORS 197.175 delegated the responsibility to local governmental units to adopt floodplain management regulations designed to promote the public health, safety, and general welfare of its citizenry.
Therefore, the City of Harrisburg does ordain as follows:
2. Findings of Fact.
a. The flood hazard areas of the City of Harrisburg are subject to periodic inundation which may result 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 may be caused by the cumulative effect of obstructions in special flood hazard areas which increase flood heights and velocities, and, when inadequately anchored, cause damage in other areas. Uses that are inadequately floodproofed, elevated, or otherwise protected from flood damage also contribute to flood loss.
3. Statement of Purpose. It is the purpose of this section to promote public health, safety, and general welfare, and to minimize public and private losses due to flooding in flood hazard areas by provisions designed to:
a. Protect human life and health;
b. Minimize expenditure of public money for costly flood control projects;
c. Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;
d. Minimize prolonged business interruptions;
e. Minimize damage to public facilities and utilities such as water and gas mains; electric, telephone and sewer lines; and streets and bridges located in special flood hazard areas;
f. Help maintain a stable tax base by providing for the sound use and development of flood hazard areas so as to minimize blight areas caused by flooding;
g. Notify potential buyers that the property is in a special flood hazard area;
h. Notify those who occupy special flood hazard areas that they assume responsibility for their actions;
i. Participate in and maintain eligibility for flood insurance and disaster relief.
4. Methods of Reducing Flood Losses. In order to accomplish its purposes, this section includes methods and provisions for:
a. Restricting or prohibiting development which is dangerous to health, safety, and property due to water or erosion hazards, or which results in damaging increases in erosion or in flood heights or velocities;
b. Requiring that development 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, dredging, and other development which may increase flood damage;
e. Preventing or regulating the construction of flood barriers which will unnaturally divert floodwaters or may increase flood hazards in other areas.
5. Definitions. Unless specifically defined below, words or phrases used in this section shall be interpreted so as to give them the meaning they have in common usage.
“Appeal” means a request for a review of the interpretation of any provision of this section or a request for a variance.
“Area of shallow flooding” means a designated Zone AO, AH, AR/AO or AR/AH on a community’s flood insurance rate map (FIRM) with a one percent or greater annual chance of flooding to an average depth of one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow.
“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. It is shown on the flood insurance rate map (FIRM) as Zone A, AO, AH, A1-30, AE, A99, AR. “Special flood hazard area” is synonymous in meaning and definition with the phrase “area of special flood hazard.”
“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year.
“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 subgrade (below ground level) on all sides.
“Below-grade crawl space” means an enclosed area below the base flood elevation in which the interior grade is not more than two feet below the lowest adjacent exterior grade and the height, measured from the interior grade of the crawl space to the top of the crawl space foundation, does not exceed four feet at any point.
Building. See “Structure.”
“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, 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 or storage of equipment or materials.
“Elevated building” means, for insurance purposes, a nonbasement building which has its lowest elevated floor raised above ground level by foundation walls, shear walls, posts, piers, pilings, or columns.
Flood or Flooding.
a. A general and temporary condition of partial or complete inundation of normally dry land areas from:
(1) The overflow of inland or tidal waters.
(2) The unusual and rapid accumulation or runoff of surface waters from any source.
(3) Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in subsection (a)(2) 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.
b. 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 (a)(1) of this definition.
Flood Elevation Study. See “Flood insurance study.”
“Flood insurance rate map (FIRM)” means the official map of a community, on which the Federal Insurance Administrator has delineated both the special hazard areas 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).
“Flood insurance study (FIS)” 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.
“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.
“Floodplain” or “flood prone area” means any land area susceptible to being inundated by water from any source. See “Flood or Flooding.”
“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.
Hazardous Material. The Oregon Department of Environmental Quality defines hazardous materials to include any of the following:
a. Hazardous waste as defined in ORS 466.005;
b. Radioactive waste as defined in ORS 469.300, radioactive material identified by the Energy Facility Siting Council under ORS 469.605 and radioactive substances defined in ORS 453.005;
c. Communicable disease agents as regulated by the Health Division under ORS Chapter 431 and ORS 433.010 to 433.045 and 433.106 to 433.990;
d. Hazardous substances designated by the United States Environmental Protection Agency (EPA) under Section 311 of the Federal Water Pollution Control Act, P.L. 92-500, as amended;
e. Substances listed by the United States EPA in Section 40 of the Code of Federal Regulations, Part 302 – Table 302.4 (list of hazardous substances and reportable quantities) and amendments;
f. Material regulated as a chemical agent under ORS 465.550;
g. Material used as a weapon of mass destruction, or biological weapon;
h. Pesticide residue;
i. Dry cleaning solvent as defined by ORS 465.200(9).
“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:
a. 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;
b. 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;
c. 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
d. Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:
(1) By an approved State program as determined by the Secretary of the Interior; or
(2) Directly by the Secretary of the Interior in states without approved programs.
“Letter of Map Change (LOMC)” means an official FEMA determination, by letter, to amend or revise effective flood insurance rate maps and flood insurance studies. The following are categories of LOMCs:
a. Conditional Letter of Map Amendment (CLOMA). A CLOMA is FEMA’s comment on a proposed structure or group of structures that would, upon construction, be located on existing natural ground above the base (one percent annual chance) flood elevation on a portion of a legally defined parcel of land that is partially inundated by the base flood.
b. Conditional Letter of Map Revision (CLOMR). A CLOMR is FEMA’s comment on a proposed project that would, upon construction, affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective base flood elevations, or the special flood hazard area.
c. Conditional Letter of Map Revision Based on Fill (CLOMR-F). A CLOMR-F is FEMA’s comment on a proposed project that would, upon construction, result in a modification of the special flood hazard area through the placement of fill outside the existing regulatory floodway.
d. Letter of Map Amendment (LOMA). An official amendment, by letter, to the flood insurance rate maps (FIRMs) based on technical data showing that an existing structure, parcel of land or portion of a parcel of land that is naturally high ground, (i.e., has not been elevated by fill) above the base flood, that was inadvertently included in the special flood hazard area.
e. Letter of Map Revision (LOMR). A LOMR is FEMA’s modification to an effective flood insurance rate map (FIRM), or flood boundary and floodway map (FBFM), or both. LOMRs are generally based on the implementation of physical measures that affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective base flood elevations, or the SFHA. The LMOR officially revises the FIRM or FBFM, and sometimes the flood insurance study (FIS) report, and, when appropriate, includes a description of the modifications. The LOMR is generally accompanied by an annotated copy of the affected portions of the FIRM, FBFM, or FIS report.
f. Letter of Map Revision Based on Fill (LOMR-F). A LOMR-F is FEMA’s modification of the special flood hazard area shown on the flood insurance rate map (FIRM) based on the placement of fill outside the existing regulatory floodway.
g. PMR. A PMR is FEMA’s physical revision and republication of an effective flood insurance rate map (FIRM) or flood insurance study (FIS) report. PMRs are generally based on physical measures that affect the hydrologic or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway, the effective base flood elevations, or the special flood hazard area.
“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 section.
“Manufactured dwelling” means a structure, transportable in one or more sections, which is built on a permanent chassis and is designed for use with or without a permanent foundation when attached to the required utilities. The term “manufactured dwelling” does not include a “recreational vehicle” and is synonymous with “manufactured home.”
“Manufactured dwelling park or subdivision” means a parcel (or contiguous parcels) of land divided into two or more manufactured dwelling lots for rent or sale.
“Mean sea level” means, for purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum (NGVD) of 1929 or other datum, to which base flood elevations shown on a community’s flood insurance rate map are referenced.
New Construction. For floodplain management purposes, “new construction” means structures for which the “start of construction” commenced on or after the effective date of a floodplain management regulation adopted by the City of Harrisburg and includes any subsequent improvements to such structures.
“Recreational vehicle” means a vehicle which is:
a. Built on a single chassis;
b. Four hundred square feet or less when measured at the largest horizontal projection;
c. Designed to be self-propelled or permanently towable by a light duty truck; and
d. Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.
Special Flood Hazard Area. See “Area of special flood hazard.”
“Start of construction” includes substantial improvement and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement, or other improvement was within 180 days from the date of the permit. 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 dwelling 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 foundations 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. For a substantial improvement, the “actual start of construction” means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building.
“Structure” means, for floodplain management purposes, a walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured dwelling.
“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” means any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the “start of construction” of the improvement. This term includes structures which have incurred “substantial damage,” regardless of the actual repair work performed. The term does not, however, include any project for improvement of a structure to correct existing violations of State or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions; or 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 by the City of Harrisburg from the terms of a floodplain management regulation.
“Violation” means the failure of a structure or other development to be fully compliant with the community’s floodplain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required in this section is presumed to be in violation until such time as that documentation is provided.
“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 National Geodetic Vertical Datum (NGVD) of 1929, or other datum, of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.
6. General Provisions.
a. Lands to Which This Section Applies. This section shall apply to all special flood hazard areas within the jurisdiction of the City of Harrisburg.
b. Basis for Establishing the Special Flood Hazard Areas. The special flood hazard areas identified by the Federal Insurance Administrator in a scientific and engineering report entitled “The Flood Insurance Study (FIS) for Linn County, Oregon and Incorporated Areas,” dated July 31, 2019, with accompanying flood insurance rate maps (FIRMs) 40143C1116G, 40143C1118G, and 41043C1119G, are hereby adopted by reference and declared to be a part of this section. The FIS and FIRM panels are on file at City Hall, located at 120 Smith St.
c. Coordination with State of Oregon Specialty Codes. Pursuant to the requirement established in ORS Chapter 455 that the City of Harrisburg administers and enforces the State of Oregon Specialty Codes, the City of Harrisburg does hereby acknowledge that the Oregon Specialty Codes contain certain provisions that apply to the design and construction of buildings and structures located in special flood hazard areas. Therefore, this section is intended to be administered and enforced in conjunction with the Oregon Specialty Codes.
d. Compliance and Penalties for Noncompliance.
(1) Compliance. All development within special flood hazard areas is subject to the terms of this section and required to comply with its provisions and all other applicable regulations.
(2) Penalties for Noncompliance. No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the terms of this section and other applicable regulations. Violations of the provisions of this section by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions) shall constitute a violation of the Harrisburg Municipal Code, punishable by a fine not to exceed $500.00 per offense. Continuing violations are assessed for each day during which the violation occurs after notice of violation has been served upon the violator. Nothing contained herein shall prevent the City of Harrisburg from taking such other lawful action as is necessary to prevent or remedy any violation.
e. Abrogation and Severability.
(1) Abrogation. This section is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this section and another ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.
(2) Severability. This section and the various parts thereof are hereby declared to be severable. If any subsection, clause, sentence, or phrase of this section is held to be invalid or unconstitutional by any court of competent jurisdiction, then said holding shall in no way affect the validity of the remaining portions of this section.
f. Interpretation. In the interpretation and application of this section, all provisions shall be:
(1) Considered as minimum requirements;
(2) Liberally construed in favor of the governing body; and
(3) Deemed neither to limit nor repeal any other powers granted under State statutes.
g. Warning and Disclaimer of Liability.
(1) Warning. The degree of flood protection required by this section 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 section 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.
(2) Disclaimer of Liability. This section shall not create liability on the part of the City of Harrisburg, any officer or employee thereof, or the Federal Insurance Administrator for any flood damages that result from reliance on this section or any administrative decision lawfully made hereunder.
7. Administration.
a. Designation of the Floodplain Administrator. The City Administrator, and his/her designee, is hereby appointed to administer, implement, and enforce this section by granting or denying development permits in accordance with its provisions. The Floodplain Administrator may delegate authority to implement these provisions.
b. Duties and Responsibilities of the Floodplain Administrator. Duties of the Floodplain Administrator, or their designee, shall include, but not be limited to:
(1) Permit Review. Review all development permits to determine that:
(a) The permit requirements of this section have been satisfied;
(b) All other required local, State, and Federal permits have been obtained and approved;
(c) Review all development permits to determine if the proposed development is located in a floodway. If located in the floodway, assure that the floodway provisions of this section in subsection (8)(b) of this section are met; and
(d) Review all development permits to determine if the proposed development is located in an area where base flood elevation (BFE) data is available either through the flood insurance study (FIS) or from another authoritative source. If BFE data is not available, then ensure compliance with the provisions of subsection (8)(a)(7) of this section;
(e) Provide to building officials the base flood elevation (BFE) applicable to any building requiring a development permit;
(f) Review all development permit applications to determine if the proposed development qualifies as a substantial improvement as defined in subsection (5) of this section;
(g) Review all development permits to determine if the proposed development activity is a watercourse alteration. If a watercourse alteration is proposed, ensure compliance with the provisions in subsection (8)(a)(1) of this section; and
(h) Review all development permits to determine if the proposed development activity includes the placement of fill or excavation.
(2) Information to Be Obtained and Maintained. The following information shall be obtained and maintained and shall be made available for public inspection as needed:
(a) Obtain, record, and maintain the actual elevation (in relation to mean sea level) of the lowest floor (including basements) and all attendant utilities of all new or substantially improved structures where base flood elevation (BFE) data is provided through the flood insurance study (FIS), flood insurance rate map (FIRM), or obtained in accordance with subsection (8)(a)(7) of this section.
(b) Obtain and record the elevation (in relation to mean sea level) of the natural grade of the building site for a structure prior to the start of construction and the placement of any fill and ensure that the requirements of subsections (7)(b)(1)(b) and (8)(b)(4) of this section are adhered to.
(c) Upon placement of the lowest floor of a structure (including basement) but prior to further vertical construction, obtain documentation, prepared and sealed by a professional licensed surveyor or engineer, certifying the elevation (in relation to mean sea level) of the lowest floor (including basement).
(d) Where base flood elevation data are utilized, obtain as-built certification of the elevation (in relation to mean sea level) of the lowest floor (including basement) prepared and sealed by a professional licensed surveyor or engineer, prior to the final inspection.
(e) Maintain all elevation certificates (EC) submitted to the community.
(f) Obtain, record, and maintain the elevation (in relation to mean sea level) to which the structure and all attendant utilities were floodproofed for all new or substantially improved floodproofed structures where allowed under this section and where base flood elevation (BFE) data is provided through the FIS, FIRM, or obtained in accordance with subsection (8)(a)(7) of this section.
(g) Maintain all floodproofing certificates required under this section.
(h) Record and maintain all variance actions, including justification for their issuance.
(i) Obtain and maintain all hydrologic and hydraulic analyses performed as required under subsection (8)(b)(4) of this section.
(j) Record and maintain all substantial improvement and substantial damage calculations and determinations as required under subsection (7)(b)(4) of this section.
(k) Maintain for public inspection all records pertaining to the provisions of this section.
(3) Requirement to Notify Other Entities and Submit New Technical Data.
(a) Community Boundary Alterations. The Floodplain Administrator shall notify the Federal Insurance Administrator in writing whenever the boundaries of the community have been modified by annexation or the community has otherwise assumed authority or no longer has authority to adopt and enforce floodplain management regulations for a particular area to ensure that all flood hazard boundary maps (FHBM) and flood insurance rate maps (FIRM) accurately represent the community’s boundaries. Include within such notification a copy of a map of the community suitable for reproduction, clearly delineating the new corporate limits or new area for which the community has assumed or relinquished floodplain management regulatory authority.
(b) Watercourse Alterations. Notify adjacent communities, the Department of Land Conservation and Development, and other appropriate State and Federal agencies, prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the Federal Insurance Administration. This notification shall be provided by the applicant to the Federal Insurance Administration as a Letter of Map Revision (LOMR) along with either:
i. A proposed maintenance plan to assure the flood-carrying capacity within the altered or relocated portion of the watercourse is maintained; or
ii. Certification by a registered professional engineer that the project has been designed to retain its flood-carrying capacity without periodic maintenance.
The applicant shall be required to submit a Conditional Letter of Map Revision (CLOMR) when required under subsection (7)(b)(3)(c) of this section. Ensure compliance with all applicable requirements in subsections (7)(b)(3)(c) and (8)(a)(1) of this section.
(c) Requirement to Submit New Technical Data. A community’s base flood elevations may increase or decrease resulting from physical changes affecting flooding conditions. As soon as practicable, but not later than six months after the date such information becomes available, a community shall notify the Federal Insurance Administrator of the changes by submitting technical or scientific data in accordance with Title 44 CFR, Section 65.3. The community may require the applicant to submit such data and review fees required for compliance with this section through the applicable FEMA Letter of Map Change (LOMC) process.
The Floodplain Administrator shall require a Conditional Letter of Map Revision prior to the issuance of a floodplain development permit for:
i. Proposed floodway encroachments that increase the base flood elevation; and
ii. Proposed development which increases the base flood elevation by more than one foot in areas where FEMA has provided base flood elevations but no floodway.
An applicant shall notify FEMA within six months of project completion when an applicant has obtained a Conditional Letter of Map Revision (CLOMR) from FEMA. This notification to FEMA shall be provided as a Letter of Map Revision (LOMR).
The applicant shall be responsible for preparing all technical data to support CLOMR/LOMR applications and paying any processing or application fees associated with the CLOMR/LOMR.
The Floodplain Administrator shall be under no obligation to sign the Community Acknowledgment Form, which is part of the CLOMR/LOMR application, until the applicant demonstrates that the project will or has met the requirements of this code and all applicable State and Federal permits.
(4) Substantial Improvement and Substantial Damage Assessments and Determinations. Conduct substantial improvement (SI) (as defined in subsection (5) of this section) reviews for all structural development proposal applications and maintain a record of SI calculations within permit files in accordance with subsection (7)(b)(2) of this section. Conduct substantial damage (SD) (as defined in subsection (5) of this section) assessments when structures are damaged due to a natural hazard event or other causes. Make SD determinations whenever structures within the special flood hazard area (as established in subsection (6)(b) of this section) are damaged to the extent that 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.
c. Establishment of Development Permit.
(1) Floodplain Development Permit Required. A development permit shall be obtained before construction or development begins within any area horizontally within the special flood hazard area established in subsection (6)(b) of this section. The development permit shall be required for all structures, including manufactured dwellings, and for all other development, as defined in subsection (5) of this section, including fill and other development activities.
(2) Application for Development Permit. Application for a development permit may be made on forms furnished by the Floodplain Administrator 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) In riverine flood zones, the proposed elevation (in relation to mean sea level), of the lowest floor (including basement) and all attendant utilities of all new and substantially improved structures, in accordance with the requirements of subsection (7)(b)(2) of this section.
(b) Proposed elevation in relation to mean sea level to which any nonresidential structure will be floodproofed.
(c) Certification by a registered professional engineer or architect licensed in the State of Oregon that the floodproofing methods proposed for any nonresidential structure meet the floodproofing criteria for nonresidential structures in subsection (8)(b)(3)(c) of this section.
(d) Description of the extent to which any watercourse will be altered or relocated.
(e) Base flood elevation data for subdivision proposals or other development when required per subsections (7)(b)(1) and (8)(a)(6) of this section.
(f) Substantial improvement calculation for any improvement, addition, reconstruction, renovation, or rehabilitation of an existing structure.
(g) The amount and location of any fill or excavation activities proposed.
d. Variance Procedure. The issuance of a variance is for floodplain management purposes only. Flood insurance premium rates are determined by Federal statute according to actuarial risk and will not be modified by the granting of a variance.
(1) Conditions for Variances.
(a) Generally, variances may be issued 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, in conformance with the provisions of subsections (7)(d)(1)(b) through (e) of this section. As the lot size increases beyond one-half acre, the technical justification required for issuing a variance increases.
(b) Variances shall only be issued upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.
(c) Variances shall not be issued within any floodway if any increase in flood levels during the base flood discharge would result.
(d) Variances shall only be issued upon:
i. A showing of good and sufficient cause;
ii. A determination that failure to grant the variance would result in exceptional hardship to the applicant;
iii. 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, or conflict with existing laws or ordinances.
(e) Variances may be issued for the repair or rehabilitation of historic structures upon a determination that the proposed repair or rehabilitation of historic structures will not preclude the structure’s continued designation as a historic structure and the variance is the minimum necessary to preserve the historic character and design of the structure.
(f) Variances may be issued by a community for new construction and substantial improvements and for other development necessary for the conduct of a functionally dependent use; provided, that the criteria of subsections (7)(d)(1)(b) through (e) of this section are met, and the structure or other development is protected by methods that minimize flood damage during the base flood and create no additional threats to public safety.
(2) Variance Notification. Any applicant to whom a variance is granted shall be given written notice that the issuance of a variance to construct a structure below the base flood elevation will result in increased premium rates for flood insurance and that such construction below the base flood elevation increases risk to life and property. Such notification and a record of all variance actions, including justification for their issuance, shall be maintained in accordance with subsection (7)(b)(2) of this section.
8. Provisions for Flood Hazard Reduction.
a. General Standards. In all special flood hazard areas, the following standards shall be adhered to:
(1) Alteration of Watercourses. Require that the flood-carrying capacity within the altered or relocated portion of said watercourse is maintained. Require that maintenance is provided within the altered or relocated portion of said watercourse to ensure that the flood-carrying capacity is not diminished. Require compliance with subsections (7)(b)(3)(b) and (8)(b)(3)(d) of this section.
(2) Anchoring.
(a) All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
(b) All manufactured dwellings shall be anchored per subsection (8)(b)(3)(d) of this section.
(3) 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.
(4) Utilities and Equipment.
(a) Water Supply, Sanitary Sewer, and On-Site Waste Disposal Systems.
i. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system.
ii. 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.
iii. On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding consistent with the Oregon Department of Environmental Quality.
(b) Electrical, Mechanical, Plumbing, and Other Equipment. Electrical, heating, ventilating, air conditioning, plumbing, duct systems, and other equipment and service facilities shall be elevated at or above the base flood level or shall be designed and installed to prevent water from entering or accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses, including the effects of buoyancy, during conditions of flooding. In addition, electrical, heating, ventilating, air conditioning, plumbing, duct systems, and other equipment and service facilities shall, if replaced as part of a substantial improvement, meet all the requirements of this section.
(5) Tanks.
(a) Underground tanks shall be anchored to prevent flotation, collapse and lateral movement under conditions of the base flood.
(b) Aboveground tanks shall be installed at or above the base flood level or shall be anchored to prevent flotation, collapse, and lateral movement under conditions of the base flood.
(6) Subdivision Proposals and Other Proposed Developments.
(a) All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) greater than 50 lots or five acres, whichever is the lesser, shall include within such proposals, base flood elevation data.
(b) All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) shall:
i. Be consistent with the need to minimize flood damage.
ii. Have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage.
iii. Have adequate drainage provided to reduce exposure to flood hazards.
(7) Use of Other Base Flood Elevation Data. When base flood elevation data has not been provided in accordance with subsection (6)(b) of this section, the local floodplain administrator shall obtain, review, and reasonably utilize any base flood elevation data available from a Federal, State, or other source, in order to administer subsection (6)(c) of this section. All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) must meet the requirements of subsection (8)(a)(6) of this section.
Base flood elevations shall be determined for development proposals that are five acres or more in size or are 50 lots or more, whichever is lesser, in any A zone that does not have an established base flood elevation. Development proposals located within a riverine unnumbered A zone shall be reasonably safe from flooding; the test of reasonableness includes use of historical data, high water marks, FEMA-provided base level engineering data, and photographs of past flooding, etc., wherever available. All residential structures and nonresidential structures that are not dry floodproofed need to be a minimum of two feet above the highest adjacent grade.
Failure to elevate at least two feet above grade in these zones may result in higher insurance rates.
(8) Structures Located in Multiple or Partial Flood Zones. In coordination with the State of Oregon Specialty Codes:
(a) When a structure is located in multiple flood zones on the community’s flood insurance rate maps (FIRM), the provisions for the more restrictive flood zone shall apply.
(b) When a structure is partially located in a special flood hazard area, the entire structure shall meet the requirements for new construction and substantial improvements.
(9) Critical Facilities Located in Multiple or Partial Flood Zones. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the special flood hazard area. Construction of new critical facilities shall be permissible within the SFHA only if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet above the base flood elevation (BFE) or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility shall also be protected to the height utilized above. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters.
b. Specific Standards for Riverine (Including All Noncoastal) Flood Zones. These specific standards shall apply to all new construction and substantial improvements in addition to the general standards contained in subsection (8)(a)(1) of this section.
(1) Flood Openings. All new construction and substantial improvements with fully enclosed areas below the lowest floor (excluding basements) are subject to the following requirements. Enclosed areas below the base flood elevation, including crawl spaces, shall:
(a) Be designed to automatically equalize hydrostatic flood forces on walls by allowing for the entry and exit of floodwaters;
(b) Be used solely for parking, storage, or building access;
(c) Be certified by a registered professional engineer or architect or meet or exceed all of the following minimum criteria:
i. A minimum of two openings;
ii. The total net area of nonengineered openings shall be not less than one square inch for each square foot of enclosed area, where the enclosed area is measured on the exterior of the enclosure walls;
iii. The bottom of all openings shall be no higher than one foot above grade;
iv. Openings may be equipped with screens, louvers, valves, or other coverings or devices; provided, that they shall allow the automatic flow of floodwater into and out of the enclosed areas and shall be accounted for in the determination of the net open area;
v. All additional higher standards for flood openings in the State of Oregon Residential Specialty Code Section R322.2.2 shall be complied with when applicable.
(2) Garages.
(a) Attached garages may be constructed with the garage floor slab below the base flood elevation (BFE) in riverine flood zones, if the following requirements are met:
i. If located within a floodway, the proposed garage must comply with the requirements of subsection (8)(b)(4) of this section;
ii. The floors are at or above grade on not less than one side;
iii. The garage is used solely for parking, building access, and/or storage;
iv. The garage is constructed with flood openings in compliance with subsection (8)(b)(1) of this section to equalize hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of floodwater;
v. The portions of the garage constructed below the BFE are constructed with materials resistant to flood damage;
vi. The garage is constructed in compliance with the standards in subsection (8)(a) of this section; and
vii. The garage is constructed with electrical and other service facilities located and installed so as to prevent water from entering or accumulating within the components during conditions of the base flood.
(b) Detached garages must be constructed in compliance with the standards for appurtenant structures in subsection (8)(b)(3)(f) of this section or nonresidential structures in subsection (8)(b)(3)(c) of this section depending on the square footage of the garage.
(3) For Riverine (Noncoastal) Special Flood Hazard Areas With Base Flood Elevations. In addition to the general standards listed in subsection (8)(a) of this section, the following specific standards shall apply in riverine (noncoastal) special flood hazard areas with base flood elevations (BFE): Zones A1-30, AH, and AE.
(a) Before Regulatory Floodway. In areas where a regulatory floodway has not been designated, no new construction, substantial improvement, or other development (including fill) shall be permitted within Zones A1-30 and AE on the community’s flood insurance rate map (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.
(b) Residential Construction.
i. New construction, conversion to, and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated at least one foot above the base flood elevation (BFE).
ii. Enclosed areas below the lowest floor shall comply with the flood opening requirements in subsection (8)(b)(1) of this section.
(c) Nonresidential Construction.
i. New construction, conversion to, and substantial improvement of any commercial, industrial, or other nonresidential structure shall:
(i) Have the lowest floor, including basement, elevated at one foot or more above the base flood elevation (BFE);
(ii) Or, together with attendant utility and sanitary facilities:
1. Be floodproofed so that below 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 section based on their development and/or review of the structural design, specifications and plans. Such certifications shall be provided to the Floodplain Administrator as set forth in subsection (7)(b)(2) of this section.
(iii) Nonresidential structures that are elevated, not floodproofed, shall comply with the standards for enclosed areas below the lowest floor in subsection (8)(b)(1) of this section.
(iv) 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 the base flood level will be rated as one foot below).
(d) Manufactured Dwellings.
i. Manufactured dwellings to be placed (new or replacement) or substantially improved that are supported on solid foundation walls shall be constructed with flood openings that comply with subsection (8)(b)(1) of this section;
ii. The bottom of the longitudinal chassis frame beam shall be at or above base flood elevation;
iii. Manufactured dwellings to be placed (new or replacement) or substantially improved shall be anchored to prevent flotation, collapse, and lateral movement during the base flood. 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 additional techniques); and
iv. Electrical crossover connections shall be a minimum of 12 inches above base flood elevation (BFE).
(e) Recreational Vehicles. Recreational vehicles placed on sites are required to:
i. Be on the site for fewer than 180 consecutive days; and
ii. 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
iii. Meet the requirements of subsection (8)(b)(3)(d) of this section, including the anchoring and elevation requirements for manufactured dwellings.
(f) Appurtenant (Accessory) Structures. Relief from elevation or floodproofing requirements for residential and nonresidential structures in riverine (noncoastal) flood zones may be granted for appurtenant structures that meet the following requirements:
i. Appurtenant structures located partially or entirely within the floodway must comply with requirements for development within a floodway found in subsection (8)(b)(4) of this section;
ii. Appurtenant structures must only be used for parking, access, and/or storage and shall not be used for human habitation;
iii. In compliance with State of Oregon Specialty Codes, appurtenant structures on properties that are zoned residential are limited to one- story structures less than 200 square feet, or 400 square feet if the property is greater than two acres in area and the proposed appurtenant structure will be located a minimum of 20 feet from all property lines. Appurtenant structures on properties that are zoned as nonresidential are limited in size to 120 square feet;
iv. The portions of the appurtenant structure located below the base flood elevation must be built using flood-resistant materials;
v. The appurtenant structure must be adequately anchored to prevent flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy, during conditions of the base flood;
vi. The appurtenant structure must be designed and constructed to equalize hydrostatic flood forces on exterior walls and comply with the requirements for flood openings in subsection (8)(b)(1) of this section;
vii. Appurtenant structures shall be located and constructed to have low damage potential;
viii. Appurtenant structures shall not be used to store toxic material, oil, or gasoline, or any priority persistent pollutant identified by the Oregon Department of Environmental Quality unless confined in a tank installed in compliance with subsection (8)(a)(5) of this section;
ix. Appurtenant structures shall be constructed with electrical, mechanical, and other service facilities located and installed so as to prevent water from entering or accumulating within the components during conditions of the base flood.
(g) Below-Grade Crawl Spaces. Below-grade crawl spaces are common in Oregon but are highly discouraged for any flood hazard areas in the City of Harrisburg. For below-grade crawl spaces to be allowed, the following guidelines are required:
i. 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 flood openings stated in subsection (8)(b)(1) of this section. Because of hydrodynamic loads, crawl space construction is not allowed in areas with flood velocities greater than five feet per second unless the design is reviewed by a qualified design professional, such as a registered architect or professional engineer. Other types of foundations are recommended for these areas.
ii. The crawl space is an enclosed area below the base flood elevation (BFE) and, as such, must have openings that equalize hydrostatic pressures by allowing the automatic entry and exit of floodwaters. The bottom of each flood vent opening can be no more than one foot above the lowest adjacent exterior grade.
iii. Portions of the building below the BFE must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawl space used to elevate the building, but also any joists, insulation, or other materials that extend below the BFE. The recommended construction practice is to elevate the bottom of joists and all insulation above BFE.
iv. Any building utility systems within the crawl space must be elevated above BFE or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions. Ductwork, in particular, must either be placed above the BFE or sealed from floodwaters.
v. The interior grade of a crawl space below the BFE must not be more than two feet below the lowest adjacent exterior grade.
vi. The height of the below-grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation wall, must not exceed four feet at any point. The height limitation is the maximum allowable unsupported wall height according to the engineering analyses and building code requirements for flood hazard areas.
vii. There must be an adequate drainage system that removes floodwaters from the interior area of the crawl space. The enclosed area should be drained within a reasonable time after a flood event. The type of drainage system will vary because of the site gradient and other drainage characteristics, such as soil types. Possible options include natural drainage through porous, well-drained soils and drainage systems such as perforated pipes, drainage tiles or gravel or crushed stone drainage by gravity or mechanical means.
viii. The velocity of floodwaters at the site shall not exceed five feet per second for any crawl space. For velocities in excess of five feet per second, other foundation types should be used.
(4) Floodways. Located within the special flood hazard areas established in subsection (6)(b) of this section are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of the 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 within the adopted regulatory floodway unless:
i. Certification by a registered professional civil engineer is provided demonstrating through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment shall not result in any increase in flood levels within the community during the occurrence of the base flood discharge; or
ii. A community may permit encroachments within the adopted regulatory floodway that would result in an increase in base flood elevations; provided, that a Conditional Letter of Map Revision (CLOMR) is applied for and approved by the Federal Insurance Administrator, and the requirements for such revision as established under 44 CFR Section 65.12 are fulfilled.
(b) If the requirements of subsection (8)(b)(4)(a) of this section are satisfied, all new construction, substantial improvements, and other development shall comply with all other applicable flood hazard reduction provisions of subsection (8) of this section.
(5) Standards for Shallow Flooding Areas. Shallow flooding areas appear on FIRMs as AO zones with depth designations or as AH zones with base flood elevations. For AO zones the base flood depths 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. For both AO and AH zones, adequate drainage paths are required around structures on slopes to guide floodwaters around and away from proposed structures.
(a) Standards for AH Zones. Development within AH zones must comply with the standards in subsections (8)(a) and (8)(b)(5) of this section.
(b) Standards for AO Zones. In AO zones, the following provisions apply in addition to the requirements in subsections (8)(a) and (8)(b)(5) of this section:
i. New construction, conversion to, and substantial improvement of residential structures and manufactured dwellings within AO zones shall have the lowest floor, including basement, elevated above the highest grade adjacent to the building, at minimum to or above the depth number specified on the flood insurance rate maps (FIRM) (at least two feet if no depth number is specified). For manufactured dwellings the lowest floor is considered to be the bottom of the longitudinal chassis frame beam.
ii. New construction, conversion to, and substantial improvements of nonresidential structures within AO zones shall either:
(i) Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, at minimum to or above the depth number specified on the flood insurance rate maps (FIRMS) (at least two feet if no depth number is specified); or
(ii) Together with attendant utility and sanitary facilities, be completely floodproofed to or above the depth number specified on the FIRM or a minimum of two feet above the highest adjacent grade if no depth number is specified, 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 the effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect as stated in subsection (8)(b)(3)(c)(i)(ii)(3) of this section.
(iii) Recreational vehicles placed on sites within AO zones on the community’s flood insurance rate maps (FIRM) shall either:
1. Be on the site for fewer than 180 consecutive days; and
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 elevation requirements of subsection (8)(b)(5)(b) of this section and the anchoring and other requirements for manufactured dwellings of subsection (8)(b)(3)(d) of this section.
(iv) In AO zones, new and substantially improved appurtenant structures must comply with the standards in subsection (8)(b)(3)(f) of this section.
(v) In AO zones, enclosed areas beneath elevated structures shall comply with the requirements in subsection (8)(a) of this section. [Ord. 987 § 1 (Exh. A), 2022.]