Ordinance No. 74-50A CITY OF TIGARD, OREGON
ORDINANCE NO. 74
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AN ORDINANCE AMENDING AND SUPPLEMENTING TITLE 18 OF THE TIGARD t
MUNICIPAL CODE BY ADDING THERETO A NEW CHAPTER DESIGNATED CHAPTER
18.57, ESTABLISHING A FLOOD PLAIN DISTRICT, DESCRIBING THE PUR-
POSES THEREOF, DEFINING THE AREA OF THE FLOOD PLAIN DISTRICT AND
PROHIBITED AND PERMITTED USES; PRESCRIBING PROCEDURES AND REQUIRE-
MENTS TO BE FOLLOWED BY THE PLANNING COMMISSION IN ALLOWING EX-
CEPTIONS AND ISSUANCE OF SPECIAL USE PERMITS; PRESCRIBING AN
EFFECTIVE DATE AND DECLARING AN EMERGENCY.
THE CITY OF TIGARD ORDAINS AS FOLLOWS:
Section 1: That Title 18 of tho Tigard M„n_Jc_ n»1 Code be, and
the same is, hereby amended and supplemented by adding
thereto a new chapter designated "Chapter 18.57 -- FLOOD PLAIN
DISTRICT" reading as follows:
18.57 FLOOD PLAIN DISTRICT (FP)
18.57.010 Intent and Purpose. The flood plain district within
the City of Tigard is superimposed
as an overlay with respect to lands classified for various uses and
purposes and is intended to give recognition to the need to protect
the public health, safety and welfare of the community through regu-
lation and control of lands within the flood plain district to there-
by mitigate potential financial burdens arising from flood damage
loss and to preserve natural drainage ways from encroaching uses
which threaten to adversely affect the property rights of citizens
of the community, personal safety and the public health by unnatural
conditions arising from upstream or downstream flood levels.
The flood plain district has for its purpose the preservation
of natural water storage areas within the Flood Plain District by
discouraging or prohibiting incompatible uses except in those in-
stances where a finding mayproperly be made by the Planning Com-
mission pursuant section 18.50.060.
18.57.020 Definitions. For purposes of this ordinance, the
following words and phrases shall be
construed to have the specific meanings assigned to them by defin-
ition as follows:
Fill - Any act by which earth, sand, gravel,
rock or any other similar material
is deposited, placed, pulled or trans-
ported and includes the conditions
resulting therefrom.
Flood A temporary rise in stream flow or
stage that results in water over-
topping stream banks and inundating
land adjacent the normal flow of
water through the stream channel.
Flood Hazard - An i=nediate danger to property or
health;as the result of inundation
of the flood plain.
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Flood plain - The relatively flat area or low lands
adjoining the channel of a river,
stream, watercourse or other body of
water which has been or may be covered
by floodwaters within the area of
applicability defined by the Flood
Plain District. -
Flood Plain District - The FP District is defined as those
areas within the City of Tigard inun-
dated by the 100 year regulatory flood
as defined by the U. S. Army Corps
of. Engineers, U. S. Geological Survey,
U. S. Bureau of Reclamation, U. S.
Soil Conservation Service and the
Oregon State Water Resources Board,
and the Washington County Department
of Public Works, among others, on
maps titled, "FLOOD PLAIN", Washington
County, Oregon, and otherwise described
as 11H UD 701 Project No. 73-16-•06',,
plates number 4 and number 5.
Flood Surface Elevation - Those elevations depicted on the flood
plain series maps are based on mean
sea level datum and their locations
are an indication of the surface
elevation at that location.
Obstruction - Any dam, wall, embankment, levee, dike,
pile, abutment, projection, excavation,
channel modification, bridge, conduit,
culvert, building, gravel, refuse, fill,
structure or matter in, along, or across
or projecting into any channel, water-
course, or flood plain area which may
impede, retard or change the direction
of the flow of water, either in itself
or by catching or collecting debris
carried by such water, or that is
placed where the flow of water might
carry the Game downstream to the dam-
age of health or property.
Regulatory flood - The flood used to define the outer
boundary lines of the FP District.
The maximum flood predicted to occur
within each one hundred (100) years.
Structure - Human buili ur cunstructed structure
or edifice or building of any kind, or
any artificially built up or composition
of physical parts adjoined together.
1.8.57.030 Permitted Uses. The following uses by their nature do
not threaten substantial obstruction
of water flow in the flood plain and do not impair the water storage
capacity of the flood plain and shall be permitted within the flood
plain district subject to the limitations in this section stated:
(1) Off-street parking and maneuvering areas, access ways
and service drives located on the ground surface. Ex-
cavation, grading and paving may occur to construct
said facilities; however, no fill shall be allowed
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for construction of said facilities other than gravel
for a paving base and only an amount of gravel commen-
surate with City construction standards for said facil-
ities shall be allowed.
(2) Accessory residential uses such as lawns, gardens or
plaritLng areas not causing substantial obstructions to
flood-waters and including fences designed to minimize
the obstruction of flood waters and flood-carried debris.
(3) Roadways, bridges or utility structures designed to not
significantly impede the flow of flood waters.
(4) Agricultural uses conducted without locating a structure
in the FP District including a boundary fence designed
to minimize the obstruction of flood waters and flood--
carried debris.
(5) Recreational uses such as bicycle and pedestrian paths,
archery range, athletic field or parks. The recreational
use shall not include any permanent structures causing
a significant obstruction to the flow of flood waters.
(6) Public and private conservation areas for the conser-
vation of water, soil, open space, forest or wildlife
resources.
18.57.040 Prohibited Uses and Activities. The following uses
and activities are
prohibited within the flood plain district except pursuant to
special permit granted by the Planning Commission based on find-
ings as by Section 18.56.060 provided.
(1) Filling
(2) Permanent structures permitted in other zoned areas of
the City.
(3) Any temporary structure which by its nature cannot be
readily removed from the flood plain area during periods
of flooding and which would significantly impede or
interfere with the flow of flood waters within the
district.
(4) Any change in the topography or terrain which would
have a substantial tendency to change the flow of
waters during flooding period or which would increase
flood hazard or alter the direction nr velocity of the
flood water flow.
(5) Subsurface sewerage disposal septic tanks and drain
fields.
18.57.050 Non-Conforming Uses. Any pre-existing condition or
structure within the flood plain
district is subject to the provisions of Chapter 18.68 of the
Tigard Municipal Code.
18.57.060 Special Permits or Exceptions. In accordance with
the procedures and
requirements set forth in Chapter 18.84 of the TigardMunicipal
Code, an application for a special use permit filed as by said
chapter stated may be considered or denied by the Planning Commission
based on written findings in conformity with the requirements of
this chapter.
An application for special permit in form prescribed by the
Planning Department of the City of Tigard shall be supported by
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the following additional data or information to enable the
Planning Commission to adequately determine whether the proposed
use is located in the flood plain district and '.f so, whether
the proposal, if granted, will conform to the ,,-poses and guide-
lines as set forth in this chapter.
(1) Plans drawn to scale, submitted in triplicate as pre-
pared by a registered professional engineer with ex-
perience in hydraulic and hydrologic principles and
processes showing the nature, location, dimensions,
elevations and topography of the site; the location of
existing and proposed structures located upon the site,
existing and proposed fill areas, and the relationship
of these to the location of the stream channel.
(2) Any documentation, photographs, water marks, and similar
evidence offered in support of the claim that the site
or area, ;n question lies above high water as defined by
theregulatoryflood.
(3) If it is determined by the Planning Commission that the
proposed use is within the flood plain district as
herein defined, the applicant shall furnish such
further information, data and evidence as may be reason-
ably available to support the granting of the petition
in accordance with the following guidelines, in the
absence of which said petition shall be denied by the
Planning Commission.
(a) Proposed improvements will not have a serious ten-
deny to change the flow of flood waters during
future flooding such as to cause a compounding
of flood h9zards and to thereby seriously inter-
fere with the intent and purposes of the flood €
plain district regulations.
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(b) No structure, fill, storage or other uses shall
be permitted which alone or in combination with
existing or future uses to materially reduce the
capacity of the flood plain area or raise the
flood surface elevation on adjacent properties,
or create a present or forseeable hazard to pub-
lic health, safety and general welfare.
The City shall reserve the right to retain a registered pro-
fessional engineer with experience in hydraulic principles and
processes for the purpose of reviewing evidence submitted in
support of any application for special use permits pursuant this
section.
18.57.070 - Standards for Permitted Structures. Any structure
or additions
to existing structures permitted within the Flood Plain District
pursuant Sections 18.56.030, 18.56.050 or 18.56.060 shall comply
with the following standards:
(1) Permitted structures such as electrical and service
equipment, etc. shall be constructed at or above the
regulatory flood protection elevation. Utility open-
ings shall be sealed and locked.
(2) The lowest floor elevation of a structure designed
for human occupancy shall be at least one and one-
half (1-1/2) feet above the flood surface elevation.
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(3) The lower portions of any structure shall be flood-
proofed or otherwise protected from significant dam-
age by inundation to a minimum flood surface elevation
one and one-half (1-1/2) feet above the surface elevation
of the regulatory flood.
(4) The design of substructures and structural members of
all buildings shall be designed to withstand expected
water pressures and velocities as well as minimize
flood risk conditions.
18.57.080 Appeal to City Council. An appeal from any decision
of the Planning Commission
may be filed with the City Recorder for hearing by the City Council
as provided by Chapter 18.92, Tigard Municipal Code.
Section 2: Inasmuch as the City of Tigard does not now have any
regulatory control over the use of flood plain lands
within the corporate limits and it is necessary for the peace,
health and safety of the people of the City of Tigard that immedi-
ate provision be made to provide control of land uses within the
Flood Plain District to thereby protect the public health, safety
and welfare and reduce financial burdens imposed upon the public
through flood damage and to protect persons and organizations
through flood damage and to protect persons and organizations
from uninformed acquisition of lands unsuited for development by
reason of flood plain exposure, an emergency is hereby declared
to exist and this Ordinance shall become effective upon its
passage by the Council and approval by the Mayor.
PASSED: By the Council, by unanimous vote of all Council members
present, after being read three times by number and
title only, this ?6 day of , 1974.
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Recer City of Tiga��
APPROVED: By the Mayor, this day of 1974.
Mayor -/City Tdgard
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