99.05
PURPOSE. The purpose of this chapter is to establish
requirements for protecting and safeguarding the general health and safety
of the public by reducing stormwater-related impacts on the quality of the
city’s water resources including drinking water.
Standards are provided for the capture and treatment of stormwater
runoff from impervious surface areas and for reducing the introduction of
pollutants into stormwater.
99.10
APPLICABILITY. The improvement of both public and
private stormwater management facilities through or adjacent to a new
development shall be the responsibility of the developer. Said
improvements shall comply with all applicable city ordinances, policies
and standards. Except as
exempt under DCC 99.15, the standards in this chapter apply to all
applications for development submitted after the effective date of this
ordinance requesting approval of one or more of the following:
A).
Land use application: Partition tentative plan; subdivision
tentative plan; planned unit development tentative plan; or site review.
B).
Development/Building Permit Application.
C).
Excavation, Grading, Driveway, or Access Permit Applications.
99.15
EXEMPTIONS. The requirements and standards of this
chapter do not apply to:
A).
An application that will result in the construction or creation of
less than five-hundred square feet of new or replaced impervious surface
area at full buildout of the development.
B).
A development/building permit application for any of the following:
1)
Development of a lot or parcel included in a land use application
that was determined by the city to comply with the standards in DCC 99.25,
Pollution Reduction Standards. The
approved land use application shall control development.
2)
Development of a lot or parcel that was not included in an
application that was determined by the city to comply with the standards
in DCC 99.25 and will result in less than five-hundred square feet of new
or replaced impervious surface within a 12 month period.
99.20
STORMWATER CONTAINMENT AND DESTINATION STANDARDS.
The purpose of these standards is to protect life and property from
flood and drainage hazards through the establishment of containment and
destination regulations for stormwater runoff from development.
A).
Stormwater Containment and Destination requirements apply to all
new development, except as exempted under 99.15.
B).
All Stormwater facilities shall be designed and constructed in
accordance with the flood control design standards of this code and the
facility design requirements set forth in the Stormwater Management
Manual.
C).
An applicant proposing new development must submit documentation to
the City showing stormwater runoff generated by the new development at the
flood control design storm level will be either:
1)
Contained on-site in accordance with the flood control design storm
and Stormwater Management Manual, or
2)
Discharged off-site in accordance with the flood control design
storm and Stormwater Management Manual into an existing stormwater
drainage facility that has the capacity to accommodate the runoff from the
proposed development. In demonstrating facility capacity, the evaluation
shall include the runoff from all current uses to the stormwater facility
and runoff from new development proposals that have already been approved
by the City as of the date the applicant submits a complete application.
Prior approvals shall include, but are not limited to, tentative plans and
final plats. Where off-site destination includes the direct discharge of
runoff into an open waterway,
the proposal must comply with the Flow Control
requirements of DCC 99.30.
3)
If the applicant cannot demonstrate that existing stormwater
drainage facilities have adequate capacity to accommodate the proposed
runoff from the new development, the applicant must construct storm
drainage facilities with adequate capacity to accommodate the runoff from
the proposed development, or construct on-site containment facilities per
(A) above.
D).
Stormwater runoff disposed of in underground systems may also be
regulated through the federal Underground Injection Control (UIC) program
under Part C of the Safe Drinking Water Act (42 U.S.C 300, Chapter 6A,
Subchapter XII) and Oregon Administrative Rule Chapter 340, Section 044.
99.25
POLLUTION REDUCTION STANDARDS.
The purpose of DCC 99.25 is to protect public health by reducing
the introduction of pollution into the waters of the city.
A).
Land use and development applications shall include pollution
reduction facilities selected from the Stormwater Management Manual as follows:
1)
For undeveloped land applications listed in DCC 99.10(A), the
selected pollution reduction facilities shall treat all the stormwater
runoff from the development site that will result from the water quality
design storm.
2)
For applications listed in DCC 99.10(A) or DCC 99.10(B) that change
or add development, the selected pollution reduction facilities shall
treat the stormwater runoff from all added and replaced impervious
surfaces that will result from the water quality design storm.
3)
Development/building permit applications shall select pollution
reduction facilities that treat all stormwater runoff from all new or
replaced impervious surface area, or an equivalent on-site area, that will
result from the water quality design storm.
B).
All pollution reduction facilities shall be sited, designed,
constructed, and maintained according to the pollution reduction
provisions and the facility design requirements set forth in the
Stormwater Management Manual.
C).
The standards in DCC 99.25 may be adjusted pursuant to the
Stormwater Management Manual.
99.30
FLOW CONTROL STANDARDS.
The purpose of DCC 99.30 is to protect waterways from the erosive
affects of increases in stormwater runoff peak flow rates and volumes that
result from the effects of impervious surfaces and land disturbances.
A).
All proposed improvements that may create stormwater flows which
drain into a stream, pipe, or conduit shall demonstrate using
methodology in the Stormwater
Management Manual that peak rates of flow delivered to an existing open
waterway will not increase during storms larger than the water quality
design storm and smaller than the flood control design storm as a result
of the proposed development.
B).
For purposes of designing the system as required by the standards
in this section the amount of impervious surface per lot is assumed to be
the maximum allowed lot coverage by structures plus all additional
impervious surface coverage.
C).
All facilities to control the rate of stormwater runoff shall be
sited, designed and
constructed according to the flow control provisions and the facility
design requirements set forth in the Stormwater Management
Manual. Flow control
facilities must be designed using one of the methodologies outlined in the
Stormwater Management Manual.
D).
The standards in DCC 99.30 may be adjusted pursuant to the
Stormwater Management Manual.
99.35
STORMWATER SOURCE CONTROLS.
All source controls shall be designed and constructed according to
the source control provisions set forth in the Stormwater Management
Manual, except when the source control would duplicate controls required
by a state or federal permit obtained by the applicant. Source control
standards set forth in DCC 99.35 apply to all improvements that result in
any of the defined site uses or characteristics listed in DCC 99.40 (A) -
(D).
A).
Fuel dispensing facilities and surrounding traffic areas where
vehicles, equipment or tanks are refueled on the premises.
A fuel dispensing facility is the area where fuel is transferred
from bulk storage tanks to vehicles, equipment, and/or mobile containers.
Exempt from these controls are propane tanks.
B).
Exterior storage of liquid materials, for example chemicals, food
products, waste oils, solvents or petroleum products in above ground
containers, in quantities of fifty gallons or more, including permanent
and temporary storage areas. Exempt
from this subsection are underground storage tanks or installations
requiring a Water Pollution Control Facility (WPCF) permit and containers
with internal protections.
C).
All facilities that store solid waste.
A solid waste storage area is a place where solid waste containers,
including compactors, dumpsters, and garbage cans, are collectively
stored. Solid waste storage
areas include areas used to collect and store refuse or recyclable
materials collection areas.
D).
All development that stockpiles or stores high-risk or low-risk
bulk materials in outdoor containers, as the terms “high-risk” and
“low-risk” are used in the Stormwater Management Manual.
Exempt from this subsection are:
1)
Materials that have no measurable solubility or mobility in water
and no hazardous, toxic or flammable properties;
2)
Materials that exist in gaseous form at ambient temperature;
3)
Materials, except for pesticides and fertilizers, which are
contained in a manner that prevents contact with stormwater.
E).
All development with a designated equipment or vehicle washing or
steam cleaning area.
F).
All development projects that disturb property suspected or known
to contain contaminants in the soil or groundwater.
99.40
STORMWATER OPERATIONS AND MAINTENANCE STANDARDS. The purpose of
this section is to ensure that through adequate operation and maintenance,
stormwater facilities protect life and property from flood and drainage
hazards and provide protection for waterways from the erosive effects of
runoff.
A).
Operation and maintenance standards apply to all facilities
designed and constructed in accordance with this Section and the
Stormwater Management Manual.
B).
Unless otherwise agreed, stormwater management facilities shall be
privately owned and shall be operated and maintained in accordance with
this ordinance and the Stormwater Management Manual.
C).
The city shall maintain public stormwater management facilities
located on city-owned property, city rights-of-way and city easements.
D).
To ensure that any city maintained stormwater management facility
can be accessed by the city for routine and/or emergency maintenance the
applicant of an applicable land use request or development permit must
dedicate easements approved by and to the city.
99.45
INSPECTION. The City Council shall designate a Health and Safety
Inspector qualified in stormwater control measures with responsibility for
evaluating proposed and completed stormwater measures and facilities. This
includes evaluation and approval of all stormwater standards and controls
required by this ordinance at stages of completion as specified in the
Stormwater Manual. The Inspector shall report to the City Council on the
implementation of the requirements of this ordinance.
99.50
ADJUSTMENT REVIEW – APPROVAL CRITERIA.
The Health and Safety Inspector shall approve, conditionally
approve, or deny an adjustment review application for Stormwater
Containment and Destination, Pollution Reduction, Flow Control and Source
Control Standards. Approval
or conditional approval shall be based on compliance with the following
applicable criteria.
A).
The requirement in DCC 99.25 (A)(1) - (3) that selected pollution
reduction facilities shall treat all the stormwater runoff that will
result from the water quality design storm may be adjusted upon a finding
that the selected pollution reduction facility will treat as much of the
runoff as possible and one of the following applies:
1)
The area generating untreated runoff is less than five-hundred
square feet of impervious surface and is isolated from the pollution
reduction facility;
2)
The area generating untreated runoff is less than five-hundred
square feet of impervious surface and it is not technically feasible to
drain the untreated runoff to the pollution reduction facility;
3)
Constructing pollution reduction facilities to treat the runoff
from the area at issue would require removal of trees or damage to other
natural resources;
4)
The area generating untreated runoff is less than five-hundred
square feet of impervious surface and limited access to the area would
prevent regular maintenance of the pollution reduction facility.
B).
The requirement in DCC 99.25 (B) that all pollution reduction
facilities be sited, designed, and constructed according to the pollution
reduction provisions and the facility design requirements set for in the
Stormwater Management Manual and that pollution reduction facilities must
be designed using one of the methodologies outlined in the Stormwater
Management Manual may be adjusted upon finding that all of the following
requirements are met:
1)
The proposed alternative design will achieve equal, or superior,
results for pollution reduction function, maintainability and safety, and
the proposed siting does not adversely affect structures or other
properties.
2)
The applicant’s written description of the proposed alternative
design has been reviewed and approved the City Engineer. The description
of the proposed design submitted for review must include all of the
following information for each component of the proposed alternative
design:
a)
Size, technical description, capacity, capital cost, design life, construction process and costs, consequences of
improper construction, operation and maintenance requirements and costs;
b)
Data on the effectiveness of proposed alternative technologies, if
available, including data from laboratory testing and pilot / full-scale
operations, and information regarding the operations of any full-scale
installations;
c)
Any other available information about the proposed design,
including peer reviewed articles, scientific or engineering journals, and
approvals from other jurisdictions.
3)
The applicant has submitted a method and schedule for monitoring
the effectiveness of the proposed design once constructed, and a schedule
for its maintenance.
4)
The applicant has submitted a signed statement that the applicant
will replace the alternative pollution reduction facility if it does not
function as proposed.
C).
The requirements in DCC 99.30 that Flow Control Standards and in
DCC 99.35 Source Control Standards be sited, designed and constructed
according to the provisions and the facility design requirements set forth
in the Stormwater Management Manual may be adjusted if the applicant can
demonstrate that the selected flow control facility will achieve the same
result as those listed in the Stormwater Management Manual.
D).
The requirement in DCC 99.40 that source controls be sited,
designed and constructed according to source control provisions set forth
in the Stormwater Management Manual may be adjusted if the applicant can
demonstrate that the selected source control will achieve the same result
as those listed in the Stormwater Management Manual.
99.55
STORMWATER MANAGEMENT MANUAL. In order to implement DCC
99.05 through 99.50, the City Council shall adopt a Stormwater Management
Manual that is consistent with the
following goals:
A).
Reduce runoff pollution from development by reducing the overall
amount of impervious surface area and extent of connectedness to
downstream drainages.
B).
Emphasize stormwater management facilities that, to the maximum
extent practicable, retain and treat stormwater utilizing on-site
controls.
C).
Emphasize stormwater management facilities that incorporate
vegetation as key element, and include design and construction
requirements that ensure landscape plant survival and overall stormwater
facility function success.
D).
Operate and maintain stormwater management facilities in accordance
with facility-specific Operation and Maintenance Plans.
E).
Reduce pollutants of concern that are generated by identified site
uses and site characteristics that are not addressed solely through the
pollution reduction measure by implementing additional specific source
control methods including reducing or eliminating pathways that may
introduce pollutants into stormwater and avoiding preventable discharges
to surface waters or groundwater.
99.60
DEFINITIONS. As used in this Chapter, unless the
context requires otherwise, the following words and phrases mean:
Development:
All improvements on a site, including buildings, other
structures, parking and loading areas, landscaping, paved or graveled
areas, grading and areas devoted to exterior display, storage, or
activities, Development includes improved open areas such as plazas and
walkways, but does not include natural geologic forms or landscapes.
Flow
control facility. Any
structure or drainage device that is designed, constructed, and maintained
to collect, retain, infiltrate, or detain surface water runoff during and
after a storm event for the purpose of controlling flow rate and volume
leaving the site.
Impervious
Surface / Area. Any
surface area that causes water to runoff the surface in greater quantities
or at an increase rate of flow from conditions preexisting to development.
Types of impervious surface include, but are not limited to,
rooftops, asphalt and concrete parking lots, driveways, roads, and
sidewalks.
Note: Slatted decks are
considered pervious surface. Gravel
surfaces are considered pervious surfaces unless they cover impervious
surfaces or are compacted to a degree that causes their runoff coefficient
to exceed eighty percent.
Nonpoint
Source Pollution: Discharge from a diffuse pollution source,
that is without a single point of origin.
Pollution
Reduction Facility. Any
structure or drainage device that is designed, constructed, and maintained
to collect and filter, retain, or detain surface water runoff during and
after a storm event for the purpose of maintaining or improving surface
and/or groundwater quality.
Property
suspected or known to contain contaminants in the soil or groundwater.
Any real property where the presence of any hazardous substance or
petroleum product indicates an existing release, past release, or
threatened release of a hazardous substance or petroleum product
into the ground, groundwater, or surface water of the property.
Runoff.
Water from rainfall, snow melt, or otherwise discharged that
flows across the ground surface instead of infiltrating the ground.
Source
Control. Any
structure, device, or design that is used to eliminate or reduce
stormwater pollution from a known source.
Stormwater.
Water derived from a storm event.
Stormwater
Management Manual. The
Dunes City Stormwater Management Manual as adopted by the city.
Stormwater
Management Facility. Any
structure or configuration of the ground that is used or, by its location,
becomes a place where stormwater flows or is accumulated, including but
not limited to pipes, curbs, gutters, catch basins, ponds, open drainage
ways, runoff control facilities, wetlands and their accessories.
Water
Quality Design Storm. A
theoretical storm for estimating the amount of stormwater runoff to be
treated. Facilities designed
to store and treat a volume of stormwater shall be sized in accordance
with the Stormwater Management Manual.
99.65
ENFORCEMENT. Failure to construct, operate and maintain
source controls as set forth in this Chapter shall be unlawful and a civil
infraction subject to the enforcement provisions of Chapter 36 of the
Dunes City Code.
A).
If Dunes City determines that maintenance or repair work is
required to be done to stormwater management facilities located in the
development, the city shall give the owner notice of the specific
maintenance and / or repair required.
The city shall set a reasonable time in which such work is to be
completed by the persons who were given notice. If the above required
maintenance and / or repair is not completed within the time set by the
city, written notice will be sent to the owner stating that the city’s
intention is to perform such maintenance and bill the owner for all
incurred expenses.
B).
If, at any time Dunes City determines that the existing facility
creates any imminent threat to public health, safety, or welfare, Dunes
City may take immediate measures to remedy said threat. No notice to the
persons as listed in (A) above shall be required under such circumstances.
All other owner responsibilities remain in effect.
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