The Dalles City Zoning Code
CHAPTER 10
8 PHYSICAL AND ENVIRONMENTAL CONSTRAINTS
§ 10.8.010.010 Purpose.
A.
The purpose of this Chapter is to provide for safe, orderly and beneficial development in areas characterized by one or more physical and/or environmental constraints.
B.
Physical and environmental constraints are considered to include, but are not limited to: slope of the land, erosive soils, natural drainage ways, floodways and floodplains, areas of high-water table, US Army Corps of Engineers flowage easements, and geologic hazard areas.
C.
In accordance with the provisions of this Chapter, a physical constraints permit shall be required for all development in areas identified as constrained.
§ 10.8.020.010 Permit Requirements.
A.
Physical Constraints Permit. A physical constraints permit shall be required for all development:
1.
In areas within all special flood hazard areas on the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRM) for the City of The Dalles;
2.
In areas identified as natural drainage ways;
3.
In areas of the 2010 Geologic Hazards Study prepared by Mark Yinger designated within Zones 1 and 4, or land in Zone 3 which is located in areas of groundwater discharge;
4.
In slopes greater than 20% where utility extensions are required, and 25% in all other cases;
5.
Which includes grading, filling, cutting, or other earth-moving activity involving more than 50 cubic yards of material on any lot or parcel of land or which includes areas of highly erosive soils;
6.
In areas designated as flowage easements by the Army Corps of Engineers; or
7.
In areas where the groundwater table is less than 10 feet below grade.
B.
Consolidation. Where the development is also subject to a site plan review, conditional use permit, subdivision, partition, planned development, or other planning action, the physical constraints permit may, at the request of the applicant, be processed simultaneously with the planning action at no additional charge. Consolidated applications may submit one plan showing all information required by this Title.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.020 Abrogation.
Abrogation. This Article is not intended to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this Title and another ordinance, easement, covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions shall prevail.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.030 Interpretation.
§ 10.8.020.040 Applications.
In addition to the requirements of Article 3.010: Application Procedures, all applications for a physical constraints permit shall be accompanied by at least three copies of a site plan. Site plan requirements are detailed in Section 10.8.020.050.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.050 Required Plans.
The following plans shall be required for any development requiring a physical constraints permit:
A.
Site Plan. A site plan clearly showing the following:
1.
Project name.
2.
Vicinity map.
3.
Scale (the scale shall be at least one inch equals 50 feet or larger).
4.
North arrow.
5.
Date.
6.
Street names and locations of all existing and proposed streets within or on the boundary of the proposed development.
7.
Lot layout with dimensions for all lot lines.
8.
Location and use of all proposed and existing buildings, fences and structures within the proposed development. Indicate which buildings are to remain and which are to be removed.
9.
Location and size of all public utilities affected by the proposed development.
10.
Location of drainage ways or public utility easements in and adjacent to the proposed development.
11.
A topographic map(s) of the site at a contour interval of five feet or less showing existing and proposed ground contours.
12.
Location of all parking areas and spaces, ingress and egress on the site, and on-site circulation.
13.
Locations of all existing natural features, including, but not limited to, all trees of a caliper greater than 12 inches in diameter, natural drainage or creeks on the site, faults, and rock outcroppings. Indicate any contemplated modifications to a natural feature.
14.
The proposed method of erosion control, water runoff control, and tree protection for the development.
15.
Building envelopes for all existing and proposed new parcels.
B.
Additional Plans and Studies. The Director may waive any of the above site plan elements, or require additional plans and studies necessary to evaluate the application.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.060 Review Procedures.
Applications for physical constraint permits shall be reviewed and decided by the Director per the provisions of Section 10.3.020.030: Ministerial Actions.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.070 Review Criteria.
Physical constraint permits shall be issued by the approving authority when the applicant has demonstrated the following:
A.
Hazards. The development will not cause damage or hazard to persons or property upon or adjacent to the area of development.
B.
Mitigation. The applicant has considered the potential hazards that the development may create and implemented reasonable measures to mitigate the potential hazards caused by the development.
C.
Impact. The applicant has taken all reasonable steps to reduce the adverse impact on the environment. Irreversible actions shall be considered more seriously than reversible actions. The approving authority shall consider the existing development of the surrounding area, and the maximum permitted development permitted by this Title.
D.
Compliance. The development is in compliance with the requirements of this Chapter and all other applicable City ordinances and State and Federal regulations.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.080 Changes to Plans.
The approving authority has the power to amend plans to include one or both of the following conditions if it is deemed necessary to mitigate any potential negative impact caused by the development:
A.
Natural Features. Require the retention and/or addition of trees and other vegetation, rocks, ponds, water courses and other natural features.
B.
Plan Changes. Require plan revision or modification to mitigate possible negative or irreversible effects upon the topography or natural features that the proposed development may cause.
(Ord. 25-1414, 7/14/2025)
§ 10.8.020.090 Permit Denial.
The approving authority may deny the physical constraint permit if, in its opinion, one or more of the following is found to apply:
A.
The proposed development will have a detrimental effect on the lands regulated and protected by this Chapter.
B.
The proposed development is inconsistent with the Comprehensive Plan.
C.
Where it appears that the proposal is part of a more extensive development that would require a master site plan, or other planning action. In this case, approval is to be postponed until a complete planning application has been processed.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.010 Statutory Authorization.
ORS 197.175 (Cities' and counties' planning responsibilities), as may be amended or superseded, delegates the State of Oregon's responsibility to adopt floodplain management regulations designed to promote the public health, safety, and general welfare of its citizenry to local governmental units.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.020 Purpose.
It is the purpose of this Article to promote public health, safety, and general welfare, and to minimize public and private losses due to flooding in special 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.
Preserve natural and beneficial floodplain functions;
D.
Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at the expense of the general public;
E.
Minimize prolonged business interruptions;
F.
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;
G.
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;
H.
Notify potential buyers that the property is in a special flood hazard area;
I.
Notify those who occupy special flood hazard areas that they assume responsibility for their actions; and
J.
Participate in and maintain eligibility for flood insurance and disaster relief.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.030 Methods of Reducing Flood Losses.
In order to accomplish its purposes, this Article 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 result 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 flood waters;
D.
Controlling filling, grading, dredging, and other development which may increase flood damage; and
E.
Preventing or regulating the construction of flood barriers which will unnaturally divert flood waters or may increase flood hazards in other areas.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.040 Findings of Fact.
A.
The flood hazard areas of The Dalles preserve the natural and beneficial values served by floodplains but 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.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.050 Applicability.
This Article shall apply to all special flood hazard areas within the jurisdiction of the City.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.060 Basis for Establishing the Special Flood Hazard Areas.
The special flood hazard areas identified by the Federal Insurance Administrator in the most current flood insurance study applicable to the City (FIS), with accompanying Flood Insurance Rate Maps (FIRM), are hereby adopted by reference and declared to be a part of this Article. The FIS and FIRM panels are on file at The Dalles Community Development Department located in The Dalles City Hall at 313 Court Street, The Dalles, OR 97058.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.070 Coordination with State of Oregon Specialty Codes.
The Oregon Specialty Codes contain certain provisions that apply to the design and construction of buildings and structures located in Special Flood Hazard areas and this Article is intended to be administered and enforced in conjunction with the Oregon Specialty Codes.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.080 Compliance and Penalties for Noncompliance.
A.
Compliance. All development within special flood hazard areas is subject to the terms of this Article and required to comply with its provisions and all other applicable regulations.
B.
Penalties for Noncompliance. No structure or land shall hereafter be constructed, located, extended, converted, or altered without full compliance with the terms of this Article and other applicable regulations. Violations of the provisions of this Article by failure to comply with any of its requirements (including violations of conditions and safeguards established in connection with conditions) shall constitute a violation subject to the provisions of Chapter 10.15. Nothing contained herein shall prevent the City from taking such other lawful action as is necessary to prevent or remedy any violation.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.090 Warning and Disclaimer of Liability.
A.
Warning. The degree of flood protection required by this Article 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 man-made or natural causes. This Article does not imply that land outside the areas of special flood hazard areas or uses permitted within such areas will be free from flooding or flood damages.
B.
Disclaimer of Liability. This Article shall not create liability on the part of the City, any officer or employee thereof, or the Federal Insurance Administrator for any flood damages that result from reliance on this Article or any administrative decision lawfully made hereunder.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.100 Administration.
A.
Designation of the Floodplain Administrator. The Director is hereby appointed to administer, implement, and enforce this Article 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 are not limited to:
1.
Permit Review. Review all development permits to:
a.
Determine that the permit requirements of this Title have been satisfied;
b.
Determine that all other required local, State, and Federal permits have been obtained and approved;
c.
Determine whether the proposed development is located in a floodway:
i.
If located in the floodway, ensure the floodway provisions of Section 10.8.030.140(G) are met;
ii.
Determine if the proposed development is located in an area where Base Flood Elevation (BFE) data is available either through the FIS or from another authoritative source. If BFE data is not available, then ensure compliance with the provisions of Section 10.8.030.120(A)(7); and
iii.
Provide to building officials the BFE to any building requiring a development permit;
d.
Determine if the proposed development qualifies as a substantial improvement;
e.
Determine if the proposed development activity is a watercourse alteration. If a watercourse alteration is proposed, ensure compliance with the provisions of Section 10.8.030.120(A)(1); and
f.
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 consistent with the Oregon Secretary of State's records retention requirements or other applicable law:
a.
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 BFE data is provided through the FIS, FIRM, or obtained in accordance with Section 10.8.030.120(A)(7).
b.
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 Sections 10.8.030.100(B)(1)(b) and 10.8.030.140(G) are adhered to.
c.
Upon placement of the lowest floor of a structure (including basement) but prior to further vertical construction, 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 BFE data is utilized, 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 submitted to the City.
f.
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 Chapter and where BFE data is provided through the FIS, FIRM, or obtained in accordance with Section 10.8.030.120(A)(7).
g.
All floodproofing certificates required under this Chapter.
h.
All variance actions, including justification for their issuance.
i.
All hydrologic and hydraulic analyses performed as required under Section 10.8.030.140(G).
j.
All substantial improvement and substantial damage calculations and determinations as required under Section 10.8.030100(B)(5).
k.
All other records submitted in connection with the provisions of this Chapter.
3.
Requirements to Notify Other Entities and Submit New Technical Data.
a.
City Boundary Alterations. The Floodplain Administrator shall notify the Federal Insurance Administrator in writing whenever the boundaries of the City have been modified by annexation or the City 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 FIRMs accurately represent the City's boundaries. Such notification shall include a copy of a map of the City suitable for reproduction and clearly delineating the new corporate limits or new area for which the City has assumed or relinquished floodplain management regulatory authority.
b.
Watercourse Alterations. Notify Wasco County, 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.
c.
The applicant shall be required to submit a Conditional Letter of Map Revision (CLOMR) when required under Section 10.8.030.100(B)(4). Ensure compliance with all applicable requirements in Sections 10.8.030.100(B)(4) and 10.8.030.120(A)(1).
4.
Requirement to Submit New Technical Data.
a.
The City's BFEs 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, the City shall notify the Federal Insurance Administrator of such changes by submitting technical or scientific data in accordance with 44 CFR 65.3. The City 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.
c.
An applicant shall notify FEMA within six months of project completion when an applicant has obtained a CLOMR from FEMA. This notification to FEMA shall be provided as a LOMR.
5.
Substantial Improvement and Substantial Damage Assessments and Determinations.
a.
Conduct substantial improvement reviews for all structural development proposal applications and maintain a record of SI calculations within permit files in accordance with Section 10.8.030.150(B).
b.
Conduct substantial damage assessments when structures are damaged due to a natural hazard event or other causes. Make substantial damage determinations whenever structures within the special flood hazard area are damaged to the extent that the cost of restoring the structure to its before damaged condition would equal or exceed 50% of the market value of the structure before the damage occurred.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.110 Permit Requirements.
A.
Physical Constraints Permit Required. A physical constraints permit shall be obtained before construction or development begins within any area horizontally within the special flood hazard area. The development permit shall be required for all structures, including manufactured dwellings, and for all other development, including fill and other development activities.
B.
Application for Physical Constraints Permit. Application for a development permit shall be made on forms furnished by the Floodplain Administrator and may include 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 with all physical constraints:
1.
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 Section 10.8.030.150(B).
2.
Existing lowest floor elevation (in relation to sea level).
3.
Proposed elevation in relation to mean sea level to which any non-residential structure will be floodproofed.
4.
Certification by a registered professional engineer or architect licensed in the State of Oregon that the floodproofing methods proposed for any structure meet the floodproofing criteria for non-residential and residential structures in Section 10.8.030.140(D).
5.
Description of the extent to which any watercourse will be altered or relocated.
6.
BFE data for subdivision proposals or other development when required and consistent with Sections 10.8.030.100(B)(1) and 10.8.030.120(A)(6).
7.
Substantial improvement calculation for any improvement, addition, reconstruction, renovation, or rehabilitation of an existing structure.
8.
The amount and location of any fill or excavation activities proposed.
C.
Development Statement.
1.
Application for permits to develop in the special flood hazard area must also include:
a.
Either:
i.
A statement confirming that the applicant has obtained a floodplain mitigation assessment of the proposed development performed by a qualified professional;
ii.
A statement that, in addition to being covered by the consultation and biological opinion issued by the National Oceanic and Atmospheric Administration's National Marine Fisheries Service (NMFS) for the Federal Emergency Management Agency's implementation of the National Flood Insurance Program in Oregon (NMFS Consultation No. NWR-2011-3197), the development proposed by the application is a project or project action that is covered by another formal consultation with NMFS or the United States Fish and Wildlife Service, pursuant to Section 4(d), 7, or 10 of the Endangered Species Act of 1973;
iii.
A statement that the development proposed by the application fits within the nature and scope of the project types that are addressed in an existing full programmatic habitat assessment of all current and reasonably foreseeable future conditions; or
iv.
A statement that the development proposed by the application is exempt from the requirement for a floodplain mitigation assessment because it is one or more of the following activities:
(a)
Normal maintenance, repairs, or remodeling of structures, such as re-roofing and replacing siding, that does not: (1) alter the footprint or expand the roof of the structure, or (2) constitute a substantial improvement or repair of substantial damage (meaning the work must be less than 50% of the market value of the structure(s));
(b)
Routine maintenance of streets, sidewalks, paths and roads (including, but not limited to, filling potholes, repaving, and installing signs and traffic signals) that does not alter contours or culverts, that is less than six inches above grade, and that does not expand paved areas;
(c)
Routine maintenance of landscaping that does not include grading, excavation, or filling;
(d)
Routine agricultural practices such as tilling, plowing, harvesting, soil amendments, and ditch cleaning that does not alter the ditch configuration and that removes all spoils from the special flood hazard area or tills spoils into fields as a soil amendment;
(e)
Routine silviculture practices (harvesting of trees), including hazardous fuels reduction and hazard tree removal with root balls left in place;
(f)
Removal of noxious weeds and hazard trees or replacement of non-native vegetation with native vegetation;
(g)
Normal maintenance of above and below ground utilities and facilities, such as replacing downed power lines and utility poles that does not result in a net change in footprint;
(h)
Normal maintenance of a levee or other flood control facility prescribed in the operations and maintenance plan for the levee or flood control facility (this does not include repair from flood damage, expansion of the prism, expansion of the face or toe or addition of protection on the face or toe with rock armor);
(i)
Habitat restoration activities;
(j)
Activities with the sole purpose of creating, restoring, or enhancing natural functions associated with floodplains, streams, lakes, estuaries, marine areas, habitat, and riparian areas, provided the activities meet federal and state standards and do not include structures, grading, fill, or impervious surfaces;
(k)
Repair to on-site septic systems, provided ground disturbance is the minimal necessary and best management practices are utilized to prevent stormwater runoff and soil erosion; and
(l)
Pre-emptive removal of documented susceptible trees to manage the spread of invasive species.
b.
If the applicant has confirmed that it has obtained a floodplain mitigation assessment under subsection (C)(1)(a)(i) above, a statement confirming that the proposed development activities, as shown on the design plans and drawings submitted with the application, include measures to incorporate all mitigation identified in the floodplain mitigation assessment as needed for no net loss of floodplain functions.
2.
The City will deny a permit to develop in the special flood hazard area unless the applicant submits a statement meeting the requirements of Section 10.8.030.110(C)(1).
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.120 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 Section 10.8.030.100(B)(3)(b) and (B)(4).
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 consistent with Section 10.8.030.140(D).
3.
Construction Materials and Methods.
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 flood waters into the system.
ii.
New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharge from the systems into flood waters.
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, if replaced as part of a substantial improvement shall 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.
Above-ground 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 BFE data.
b.
All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) shall:
7.
Use of Other Base Flood Elevation Data.
a.
When BFE data has not been provided in accordance with Section 10.8.030.060, the Floodplain Administrator shall obtain, review, and reasonably utilize any BFE data available from a Federal, State, or other source to administer Section 10.8.030.120. All new subdivision proposals and other proposed new developments (including proposals for manufactured dwelling parks and subdivisions) must meet the requirements of Section 10.8.030.120(A)(6).
b.
BFEs 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 BFE. 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., where available. The elevation of residential structures and non-residential structures that are not dry floodproofed must be two feet above 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 City's 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.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.130 Specific Standards for Riverine (Including All Non-Coastal) Flood Zones.
These specific standards shall apply to all new construction and substantial improvements in addition to the General Standards contained in Section 10.8.030.120 Provisions for Flood Hazard Reduction, Subsection A.
A.
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 BFE, including crawl spaces shall:
1.
Be designed to automatically equalize hydrostatic flood forces on walls by allowing for the entry and exit of floodwaters;
2.
Be used solely for parking, storage, or building access;
3.
Be certified by a registered professional engineer or architect or meet or exceed all of the following minimum criteria:
a.
A minimum of two openings;
b.
The total net area of non-engineered 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;
c.
The bottom of all openings shall be no higher than one foot above grade;
d.
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; and
e.
All additional higher standards for flood openings in the State of Oregon Residential Specialty Codes Section R322.2.2 shall be complied with when applicable.
4.
Garages.
a.
Attached garages may be constructed with the garage floor slab below the 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 Section 10.8.030.140(G);
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 Section 10.8.030.130(A) 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 Section 10.8.030.120(A); 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 accessory structures in Section 10.8.030.140(F) or non-residential structures in Section 10.8.030.140(D) depending on the square footage of the garage.
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.140 For Riverine (Non-Coastal) Special Flood Hazard Areas with Base Flood Elevations.
In addition to the general standards listed in Section 10.8.030.120(A), the following specific standards shall apply in Riverine (non-coastal) Special Flood Hazard areas with BFE: Zones A1-A30, 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 City's FIRM unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the City and will not result in the net loss of flood storage volume.
B.
Residential Construction.
1.
New construction, conversion to, and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot above the BFE.
2.
Enclosed areas below the lowest floor shall comply with the flood opening requirements in Section 10.8.030.130(A).
C.
Non-Residential Construction.
1.
New construction, conversion to, and substantial improvement of any commercial, industrial, or other non-residential structure shall:
a.
Have the lowest floor, including basement elevated at or above the BFE; or
b.
Together with attendant utility and sanitary facilities:
i.
Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
ii.
Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
iii.
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 Section 10.8.030.100(B)(2).
2.
Non-residential structures that are elevated, not floodproofed, shall comply with the standards for enclosed areas below the lowest floor in Section 10.8.030.130(A).
3.
Applicants floodproofing non-residential 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.
1.
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 Section 10.8.030.130(A);
2.
The bottom of the longitudinal chassis frame beam shall be at or above BFE;
3.
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;
4.
Electrical crossover connections shall be a minimum of one foot above BFE.
E.
Recreational Vehicles.
1.
Recreational vehicles placed on sites are required to be on the site for fewer than 180 consecutive days and:
a.
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
b.
Meet the requirements of Section 10.8.030.140(D), including the anchoring and elevation requirements for manufactured dwellings.
F.
Accessory Structures. Relief from elevation or floodproofing requirements for residential and non-residential structures in Riverine (Non-Coastal) flood zones may be granted for accessory structures that meet the following requirements:
1.
Accessory structures located partially or entirely within the floodway must comply with requirements for development within a floodway found in Section 10.8.030.140(G);
2.
Accessory structures must only be used for parking, access, and/or storage and shall not be used for human habitation;
3.
In compliance with State of Oregon Specialty Codes, accessory 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 accessory structure will be located a minimum of 20 feet from all property lines. Accessory structures on properties that are zoned as non-residential are limited in size to 120 square feet;
4.
The portions of the accessory structure located below the BFE must be built using flood resistant materials;
5.
The accessory 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;
6.
The accessory structure must be designed and constructed to equalize hydrostatic flood forces on exterior walls and comply with the requirements for flood openings in Section 10.8.030.130(A);
7.
Accessory structures shall be located and constructed to have low damage potential;
8.
Accessory 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 incompliance with Section 10.8.030.120(A)(5); and
9.
Accessory 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.
Floodways. Located within the special flood hazard areas established in Section 10.8.030.060 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:
1.
Prohibit encroachments, including fill, new construction, substantial improvements, and other development within the adopted regulatory floodway unless:
a.
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 City during the occurrence of the base flood discharge; or
b.
The City may permit encroachments within the adopted regulatory floodway that would result in an increase in BFEs.
2.
If the requirements of Section 10.8.030.140(G) are satisfied, all new construction, substantial improvements, and other development shall comply with all other applicable flood hazard reduction provisions of Section 10.8.030.120.
H.
Standards for Shallow Flooding Areas. Shallow flooding areas appear on FIRMs as AO zones with depth designations or as AH zones with BFEs. 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.
1.
Standards for AH Zones. Development within AH Zones must comply with the standards in Sections 10.8.030.140(G) and 10.8.030.140(A).
2.
Standards for AO Zones. In AO zones, the following provisions apply in addition to the requirements in Sections 10.8.030.140(G) and 10.8.030.140(H):
a.
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 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.
b.
New construction, conversion to, and substantial improvements of non-residential 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 FIRM (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 consistent with Section 10.8.030.140(D).
c.
Recreational vehicles placed on sites within AO Zones on the City's FIRM shall be on the site for fewer than 180 consecutive days and either:
i.
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
ii.
Meet the elevation requirements of Section 10.8.030.140(H) and the anchoring and other requirements for manufactured dwellings of Section 10.8.030.140(D).
d.
In AO zones, new and substantially improved accessory structures must comply with the standards in Section 10.8.030.140(F).
e.
In AO zones, enclosed areas beneath elevated structures shall comply with the requirements in Section 10.8.030.130(A).
(Ord. 25-1414, 7/14/2025)
§ 10.8.030.150 Variance Procedure.
The issuance of a variance under this Article 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. Variance applications unrelated to floodplain standards described in this Article shall be processed and reviewed consistent with Section 10.3.070.
A.
Conditions for Variances.
1.
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, consistent with the provisions of Sections 10.8.030.150(A)(3) and (5) and (B). As the lot size increases beyond one-half acre, the technical justification required for issuing a variance increases.
2.
Variances shall only be issued upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief.
3.
Variances shall not be issued within any floodway if any increase in flood levels during the base flood discharge would result.
4.
Variances shall only be issued upon:
a.
A showing of good and sufficient cause;
b.
A determination that failure to grant the variance would result in exceptional hardship to the applicant; and
c.
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.
5.
Variances may be issued by the City for new construction and substantial improvements and for other development necessary for the conduct of a functionally dependent use provided that the criteria of Section 10.8.030.150(A)(2) and (4) are met, and the structure or other development is protected by methods that minimize flood damages during the base flood and create no additional threats to public safety.
B.
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 BFE will result in increased premium rates for flood insurance and that such construction below the BFE increases risks to life and property. Such notification and a record of all variance actions, including justification for their issuance shall be maintained in accordance with Section 10.8.030.150(B).
(Ord. 25-1414, 7/14/2025)
§ 10.8.040.010 Purpose.
This Article describes the permit requirements for lands proposed to be developed within the areas designated Zones 1 to 6 on the maps and in the 2010 Geologic Hazards Study prepared by Mark Yinger, R.G., Hydrogeologist. Land within Zones 1 and 4, land within Zones 2, 3, or 5 that exceed a slope of 30%, or land in Zone 3 which is located in areas of groundwater discharge, have been determined to be within a geographic area that has characteristics which make the ground potentially unstable. Any cut, fill, or construction on these sites may add to this potential instability. The requirements of this Article are intended to reduce as much as possible the adverse effects of development for the owner and for other properties which may be affected by a ground movement.
§ 10.8.040.020 Applicability.
The requirements of this Article shall apply to all new development, including, but not limited to, streets, driveways, parking areas, sidewalks, retaining walls, drainage structures, buildings and other structures, and to additions and modifications to existing development which increase the footprint. Detached buildings of 200 square feet are exempt from the requirements of this Article.
§ 10.8.040.030 Permit Requirements.
A physical constraints permit shall be required for new development and additions as described above in Section 10.8.040.020 for all proposed development activities located within hazard areas in Zones 1 through 6, per the requirements of Article 8.020: Review Procedures. The following shall also be required as part of the physical constraints permit:
A.
Geologic Impact Statement. A site-specific geologic impact statement prepared by a qualified geotechnical engineer or an engineering geologist. If the size of a proposed development is increased, or the location of a proposed development is changed, a new impact statement may be required.
B.
Certification of Plans. A statement prepared by a qualified geotechnical engineer or an engineering geologist certifying that the development plans and specifications comply with the limitations imposed by the geologic impact statement, and that the proposed construction will not adversely affect the site and adjacent properties.
§ 10.8.040.040 As-Built Certification.
Within 30 days after completion of the project, and before final acceptance of public improvements by the City Engineer, the applicant shall submit to the Director a statement prepared by a qualified geotechnical engineer or an engineering geologist certifying that the construction was completed in accordance with the plans and specifications as they relate to mitigation of the geologic impacts to the site and adjacent properties.
§ 10.8.050.010 Purpose.
This Article describes standards for control of runoff, and the permit requirements for control of erosion and slope failure, and for cuts and fills.
§ 10.8.050.020 Runoff Control.
Any development which increases the natural runoff by decreasing the infiltration of the soil by any means shall conform to the following standards:
A.
Roof Drainage. All roof drainage, except one- and two-family residential, must be collected, controlled and directed either by underground pipe or concrete or asphalt gutter to a City street or storm drain or to a natural watercourse. The method of control and conveyance of stormwater to the storm system shall be determined by the approving authority.
B.
Hard Surface Drainage. All drainage from driveways, parking areas and other impervious surfaces must be collected, controlled and directed to a City street or storm drain or natural watercourse by underground pipe or concrete or asphalt gutter or disposed of on site. The method of control and conveyance of stormwater to the storm system shall be determined by the approving authority.
C.
Dry Wells. Connection to dry wells may be allowed for roof and hard surface drainage only with the approval of the City Engineer, where City storm system is not available within 300 feet, the groundwater table is well below the proposed dry well during all seasons, and a non-remonstrance agreement for future street and storm sewer improvements is signed by the applicant and recorded with the deed.
D.
Alternative Stormwater Disposal Systems. Any alternative methods of stormwater disposal not herein described, such as a bio-swale or leach field, must be approved by the City Engineer.
§ 10.8.050.030 Erosion and Slope Failure.
All development on lands with highly erosive lands or slopes greater than 25% (4:1), and all development which removes vegetation or disturbs topsoil and leaves the disturbed soil at a slope of 50% (2:1) or more shall require a physical constraints permit, per the provisions of Article 8.020: Review Procedures, and comply with the following standards:
A.
Re-vegetation. Any exposed soil shall be revegetated in a manner to reestablish a complete vegetative cover within 1 year of time of planting. If irrigation is not provided, then the exposed soil must be planted with species which can survive without irrigation.
B.
Maintenance. Vegetative cover, rock, dry or conventional masonry, or other permanent cover must be maintained in perpetuity on areas which have been disturbed.
C.
Temporary Erosion Control. During construction, erosion control measures such as straw bales, sediment fences, etc., shall be incorporated into plans to control erosion from the site as needed.
D.
Exception. The above restrictions shall not apply to areas of exposed bedrock which exhibit no erosion potential.
E.
Utility Anchors. Concrete anchors shall be constructed when pipelines are installed at grades of 20% or greater, in accordance with City standards.
§ 10.8.050.040 Cuts and Fill.
All cuts, grading or fills shall be designed in a manner that will be stable for the intended use, conform to the applicable requirements of the most current versions of the Uniform Building Code and the Oregon Structural Specialty Code, and meet the following requirements:
A.
Documentation. Prior to initiating any cut or fill in excess of 10 cubic yards, the applicant shall submit documentation showing the amount and location of each cut or fill.
B.
Permits. Any cuts and/or fills outside of geohazard Zone 2 of the February 2011 Geohazard Study greater than 50 cubic yards but less than 250 cubic yards shall require a physical constraints permit with an application with a drawing having a primary focus on erosion control. Any cuts and/or fills in geohazard Zone 2 of the February 2011 Geohazard Study greater than 50 cubic yards shall require a physical constraints permit, per the provisions of Article 8.020: Review Procedures.
C.
250+ Cubic Yards.
1.
Any cuts and/or fills outside of geohazard Zone 2 of the February 2011 Geohazard Study greater than 250 cubic yards but less than 500 cubic yards require a drawing and either engineered plans or a letter from a licensed professional engineer stating that no engineered plans are required in the engineer's professional opinion as the activity presents no danger to surrounding properties. Any cuts and/or fills in the Zone 2 of the February 2011 Geohazard Study over 250 cubic yards, or over 500 cubic yards outside Zone 2 of the February 2011 Geohazard Study, must be designed by a licensed professional engineer.
2.
If the cut and/or fill is not a City street or a public right-of-way, a licensed professional engineer shall declare to the City, after the cut and/or fill is completed, that it was constructed to plans and meets all standards set forth in the approved plans.
D.
Right to Inspect. Nothing in this Article shall abridge the City's right to inspect work in progress or in its completed state, to make appropriate measurements and tests to determine if the cut and fill was made according to plan, and to require alterations prior to final approval of the cut and/or fill.
E.
Master Plans. Any development or partitioning which is proposed on erosive and slope failure lands must be shown on a master plan at the time the final plan or plat is filed. All development must comply with the master plan. Any improvements necessary for the implementation of the master plan (e.g., storm drains, gutters, etc.), must be constructed by the applicant prior to any development occurring on the parcels.
E .
Foundations. All structures in erosive and slope failure lands shall have foundations which have been designed by a geotechnical engineer.
F.
Building Envelopes. All newly created lots or lots modified by a lot line adjustment must include a buildable area of sufficient size to accommodate the uses permitted in the underlying zone, unless the division or lot line adjustment is for open space or conservation purposes.
§ 10.8.060.010 Purpose.
The purpose of this Article is to ensure that development proposals for lands within the Army Corps of Engineers' flowage easement for the Bonneville Lock and Dam Project are reviewed for consistency with the limitations imposed by this easement.
§ 10.8.060.020 Applicability.
The review described in this Article applies to all lands and parcels noted on the Real Estate Segment Map No. 21 for the Bonneville Lock and Dam Project as having a recorded flowage easement.
§ 10.8.060.030 Review Procedures.
A.
Permit Requirements. A physical constraints permit shall be required for all structures and other development activities located in an Army Corps flowage easement, per the requirements of Article 8.020: Review Procedures.
B.
Review. The Director shall review the physical constraints permit to determine whether or not, and to what extent, any development may be allowed. The Director will then forward the physical constraints permit to the Corps for final approval.