ORD 98-31 MUNICIPAL CODE UPDATE SURFACE & STORMWATER MANAGEMENTORDINANCE NUMBER 98-31
AN ORDINANCE of the City of Bainbridge Island Washington,
relating to Surface and Stormwater Management; amending
Chapter 15.20 of the Bainbridge Island Municipal Code.
WHEREAS, the Washington State Legislature has enacted State law with minimum
requirements for surface and stormwater management.
WHEREAS, the City Council wishes to enact standards for surface and stormwater
management consistent with the State law minimum requirements;
WHEREAS, stormwater pollution is a problem that is associated with land utilization and
development and the common occurrence of potential pollutants such as pesticides, fertilizers,
petroleum products, pet wastes and numerous others;
WHEREAS, land utilization and development increases both the volume and duration of
peak flows and the resulting erosion, scouring, and deposition of sediment affect the ecological
balance in the City' s streams, creeks, ponds, lakes and other water bodies;
WHEREAS, sedimentation and stormwater pollution decrease the diversity of species
and allows more tolerant, and usually less desirable, species to remain;
WHEREAS, stormwater pollution may cause or contribute to closures of shellfish beds
and swimming beaches and cause restrictions on public use of the waters within the City;
WHEREAS, an expanding population and increased development of land have led to
water quality degradation through discharge of nutrients, metals, oil and grease, toxic materials,
and other detrimental substances including, insect and weed control compounds and numerous
others;
WHEREAS, an expanding population and increased development of land have increased
drainage, stormwater, and surface water runoff problems within the City;
WHEREAS, health and safety hazards exist to lives and property because of uncontrolled
water runoff on City streets and highways;
WHEREAS, continuation of present stormwater management practices will lead to water
quality degradation, erosion, property damage, and endanger the health and safety of the
inhabitants of the City;
WHEREAS, future surface and stormwater problems and dangers will be reduced or
avoided if existing properties and future developers, both private and public, provide for
stormwater quality and quantity controls;
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WHEREAS, stormwater quality and quantity controls can be achieved when land is
developed or redeveloped by implementing appropriate Best Management Practices (BMPs);
WHEREAS, Best Management Practices can be expected to perform as intended only
when properly designed, constructed and maintained; now therefore,
THE CITY COUNCIL OF THE CITY OF BAINBRIDGE ISLAND, WASHINGTON,
DO ORDAIN AS FOLLOWS:
Section 1.
follows:
Chapter 15.20 of the Bainbridge Island Municipal Code is amended as
15.20.010 Purpose
The provisions of this Chapter are intended to guide and advise all who conduct new
development or redevelopment within the City. The provisions of this Chapter establish the
minimum requirements that must be met to permit a property to be developed or redeveloped
within the City. The purpose of this Chapter is to:
A. Minimize or eliminate water quality degradation;
bodies;
B. Prevent erosion and sedimentation in creeks, streams, ponds, lakes and other water
C. Protect property owners adjacent to existing and developing lands from increased
runoff rates which could cause erosion of abutting properties;
D. Preserve and enhance the suitability of waters for contact recreation, fishing, and
other beneficial uses;
E. Preserve and enhance the aesthetic quality of the water;
F. Promote sound development policies which respect and preserve City and County
surface water, ground water and recreational waters;
G. Ensure the safety of City roads and rights-of-way;
H. Decrease stormwater-related damage to public and private property from existing and
future runoff;
I. Protect the health, safety and welfare of the inhabitants of the City;
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It is the purpose of this Chapter to:
A. Minimize water quality degradation and sedimentation in streams, ponds, lakes,
wetlands and other water bodies;
B. Minimize the impact of increased runoff, erosion and sedimentation caused by land
development and poor maintenance practices;
C. Maintain and protect groundwater resources;
D. Minimize adverse impacts of alterations on ground and surface water quantities,
locations and flow patterns;
E. Decrease potential landslide, flood and erosion damage to public and private property;
F. Promote site planning and construction practices that are consistent with natural
topographical, vegetational and hydrological conditions;
G. Maintain and protect the City stormwater management infrastructure and downstream
systems and properties;
H. Provide a means of regulating clearing and grading of private and public land while
minimizing water quality impacts in order to protect public health and safety; and
I. Provide minimum development regulations and construction procedures that will
preserve, replace or enhance, to the maximum extent possible, existing vegetation and that will
preserve and enhance the natural qualities of lands, wetlands and water bodies.
15.20.020 Definitions
A. "American Public Works Association or APWA" means the adopted edition of the
Washington State Chapter of the American Public Works Association.
B. "Approval" means the proposed work or completed work conforms to this Chapter in the
opinion of the Director.
C. "As-graded" means the extent of surface conditions on completion of grading.
D. "Basin plan" means a plan and all implementing regulations and procedures including but
not limited to land use management adopted by ordinance for managing surface and storm water
management facilities and features within individual sub-basins.
E. "Bedrock" means the more or less solid rock in place either on or beneath the surface of the
earth. It may be soft, medium, or hard and have a smooth or irregular surface.
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F. "Bench" means a relatively level step excavated into earth material on which fill is to be
placed.
G. "Best Management Practice" (BMP) means physical, structural, and/or managerial
practices that, when used singly or in combination, prevent or reduce pollution of water. BMPs
are listed and described in the Manual.
H. "City" shall mean the City of Bainbridge Island.
I. "City Council" shall mean the legislative body for the City of Bainbridge Island.
J. "City Engineer" shall refer to the Professional Engineer that oversees the Engineering
Division of the City of Bainbridge Island.
K. "Civil engineer" means a professional engineer licensed in the State of Washington in Civil
Engineering who is experienced and knowledgeable in the practice.
L. "Civil engineering" means the application of the knowledge of the forces of nature,
principles of mechanics and the properties of materials and to the evaluation, design and
construction of civil works.
M. "Clearing" means the destruction and removal of vegetation by manual, mechanical, or
chemical methods.
N. "Commercial agriculture" means those activities conducted on lands defined in RCW
84.34.020(2), and activities involved in the production of crops or livestock for wholesale trade.
An activity ceases to be considered commercial agriculture when the area on which it is
conducted is proposed for conversion to a nonagricultural use or has been idle for more than five
(5) years, unless the idle land is registered in a federal or State soils conservation program, or
unless the activity is maintenance of irrigation ditches, laterals, canals, or drainage ditches related
to an existing and ongoing agricultural activity.
O. "Compaction" means densification of a fill by mechanical means.
P. "Critical areas" means, at a minimum, areas which include wetlands, areas with a critical
recharging effect on aquifers used for potable water, fish and wildlife habitat conservation areas,
frequently flooded areas, geologically hazardous areas, including unstable slopes, and associated
areas and ecosystems. Reference BIMC 16.20.
Q. "Design storm" means a prescribed hyetograph and total precipitation amount (for a specific
duration recurrence frequency) used to estimate runoff for a hypothetical storm for the purposes
of analyzing existing drainage, designing new drainage facilities or assessing other impacts of a
proposed project on the flow of surface water. (A hyetograph is a graph of percentages of total
precipitation for a series of time steps representing the total time during which the precipitation
occurs. )
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R. "Detention" means the release of stormwater runoff from a specific site at a slower rate than
it is collected by the stormwater facility system, the difference being held in temporary storage.
S. "Detention facility" means an above or below ground facility, such as a pond or tank, that
temporarily stores stormwater runoff and subsequently releases it at a slower rate than it is
collected by the drainage facility system. There is little or no infiltration of stored stormwater.
T. "Director" means the Public Works Director, or designee, shall administer this Chapter and
shall be referred to as the Director. The Director shall have the authority to develop and
implement administrative procedures to administer and enforce this Chapter.
U. "Drainage basin" means a geographic and hydrologic subunit of a watershed. Further
clarification is located in the drainage reconnaissance study or basin assessment.
V. "Earth material" means any rock, natural soil or fill and/or any combination thereof.
W. "Ecology" means the Washington State Department of Ecology.
X. "Engineering geologist" means a geologist experienced and knowledgeable in engineering
geology.
Y. "Engineering geology" means the application of geologic knowledge and principles in the
investigation and evaluation of naturally occurring rock and soil for use in the design of civil
works.
Z. "Erosion" means the wearing away of the land surface by running water, wind, ice, or other
geological agents, including such processes as gravitational creep, or the detachment and
movement of soil or rock fragments by water, wind, ice, or gravity.
AA."Excavation" means the mechanical removal of earth material.
BB."Existing site conditions" means: 1 ) For developed sites with stormwater facilities that
have been constructed to meet the Minimum Requirements of the Manual. Existing site
conditions shall mean the existing conditions on the site. 2) For developed sites that do not have
stormwater facilities that meet the Minimum Requirements, existing site conditions shall mean
the conditions that existed prior to local government adoption of a stormwater management
program(1985). If in question, the existing site conditions shall be documented by aerial
photograph records, or other appropriate means. 3) For all sites in water quality sensitive areas
as identified under Minimum Requirement #7, Water Quality Sensitive Areas, existing site
conditions shall mean undisturbed forest, for the purpose of calculating runoff characteristics.
4) For all undeveloped sites outside of water quality sensitive areas, existing site conditions shall
mean the existing conditions on the site.
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CC."Experimental BMP" means a BMP that has not been tested and evaluated by the
Department of Ecology in collaboration with local governments and technical experts.
DD."Fill" means a deposit of earth material placed by artificial means.
EE."Forest practice" means any activity conducted on or directly pertaining to forest land and
relating to growing, harvesting, or processing timber, as defined by RCW 76.09.050.
FF. "Frequently flooded areas" means the 100-year floodplain designations of the Federal
Emergency Management Agency and the National Flood Insurance Program. Reference BIMC
15.16.
GG."Geologically hazardous areas" means areas susceptible to erosion, sliding, earthquakes, or
other geological events. They pose a threat to the health and safety of citizens when used as sites
for commercial, residential or industrial development. Reference BIMC 16.20.
HH."Grade" means the slope of a road, channel, or natural ground, the finished surface of a
canal bed, roadbed, top of embankment, or bottom of excavation or any surface prepared for the
support of construction such as paving or the laying of a conduit. 1 ) Existing Grade: the grade
prior to grading. 2) Rough Grade: the stage at which the grade approximately conforms to the
approved plan. 3 ) Finish Grade: the final grade of the site which conforms to the approved
plan.
II. "Grade, to" B "(To grade)" means to finish the surface of a canal bed, roadbed, top of
embankment or bottom of excavation.
JJ. "Gradient terrace" means an earth embankment or a ridge-and-channel constructed with
suitable spacing and an acceptable grade to reduce erosion damage by intercepting surface runoff
and conducting it to a stable outlet at a stable nonerosive velocity.
KK."Ground water" means water in a saturated zone or stratum beneath the surface of land or a
surface water body.
LL."Hydroperiod" means the seasonal occurrence of flooding and/or soil saturation; it
encompasses depth, frequency, duration, and seasonal pattern of inundation.
MM."Illicit discharge" means all non-stormwater discharges to stormwater drainage systems
that cause or contribute to a violation of State water quality, sediment quality or ground water
quality standards, including but not limited to, sanitary sewer connections, industrial process
water, interior floor drains, car washing and greywater systems.
NN."Impervious surface" means a hard surface area which either prevents or retards the entry
of water into the soil mantle as under natural conditions prior to development, and/or a hard
surface area which causes water to run off the surface in greater quantities or at an increased rate
of flow from the flow present under natural conditions prior to development. Common
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impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways,
parking lots, storage areas, sport courts, concrete or asphalt paving, gravel roads, packed earthen
materials, and oiled, macadam or other surfaces which similarly impede the natural infiltration of
stormwater. Open, uncovered retention/detention facilities shall not be considered as impervious
surfaces.
O0."Inter~ow" means that portion of rainfall that in~ltrates into the soil and moves laterally
through the upper soil horizons until intercepted by a stream channel or until it retums to the
surface for example, in a wetland, spring or seep.
PP. "Land disturbing activity" means any activity that results in a change in the existing soil
cover (both vegetative and nonvegetative) and/or the existing soil topography. Land disturbing
activities include, but are not limited to demolition, construction, clearing, grading, filling and
excavation.
QQ."Large Parcel Erosion and Sediment Control (ESC) Plan" means a plan to implement
BMPs(see bbb in handout) to control pollution generated during land disturbing activity.
Guidance for preparing a Large Parcel ESC Plan is contained in the Manual.
RR."Mitigation" means, in the following order of preference: 1 ) Avoiding the impact altogether
by not taking a certain action or part of a action; 2) Minimizing impacts by limiting the degree
or magnitude of the action and its implementation, by using appropriate technology, or by taking
affirmative steps to avoid or reduce impacts; 3 ) Rectifying the impact by repairing, rehabilitating
or restoring the affected environment; 4) Reducing or eliminating the impact over time by
preservation and maintenance operations during the life of the action.
SS. "Natural location" means the location of those channels, swales, and other non-manmade
conveyance systems as defined by the first documented topographic contours existing for the
subject property, either from maps or photographs, or such other means as appropriate.
TT."New development" means the following activities: land disturbing activities, structural
development, including construction, installation or expansion of a building or other structure;
creation of impervious surfaces (taking place on previously undeveloped areas); Class IV -
general Forest Practices that are conversions from timber land to other uses; and subdivision and
short subdivision of land as defined in RCW 58.17.020. All other Forest Practices and
commercial agriculture are not considered new development.
UU."Permanent Stormwater Quality Control (PSQC) Plan" means a plan which includes
permanent BMPs for the control of pollution from stormwater runoff after construction and/or
land disturbing activity has been completed. For small sites, this requirement is met by
implementing a plan as required under Small Parcel Minimum Requirements of this Chapter.
Reference 15.20,060A. Guidance on preparing a PSQC Plan is contained in the Manual.
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VV."Person" means any individual, partnership, corporation, association, organization,
cooperative, public or municipal corporation, agency of the State, or local government unit,
however designated.
WW."Pollution" means contamination or other alteration of the physical, chemical, or biological
properties, of waters of the State, including change in temperature, taste, color, turbidity, or odor
of the waters, or such discharge of any liquids, gaseous, solid, radioactive or other substance into
any waters of the State as will or is likely to create a nuisance or render such waters harmful,
detrimental or injurious to the public health, safety or welfare, or to domestic, commercial,
industrial, agricultural, recreational, or other legitimate beneficial uses, or to livestock, wild
animals, birds, fish or other aquatic life.
XX."Redevelopment" means, on an already developed site, the creation or addition of
impervious surfaces, structural development including construction, installation or expansion of
a building or other structure, and/or replacement of impervious surface that is not part of a
routine maintenance activity, and land disturbing activities associated with structural or
impervious redevelopment.
YY."Redevelopmented' means the portion of a piece of property which is directly subject to
development.
ZZ."Regional retention/detention system" means a stormwater quantity control structure
designed to correct existing excess surface water runoff problems of a basin or sub-basin for two
or more properties. The area downstream has been previously identified as having existing or
predicted significant and regional flooding and/or erosion problems. This term is also used when
a detention facility is used to detain stormwater runoff from a number of different businesses,
developments or areas within a catchment.
AAA."Retention/detention facility (R/D)" means a type of drainage facility designed either to
hold water for a considerable length of time and then release it by evaporation, plant
transpiration, and/or infiltration into the ground; or to hold surface and stormwater runoff for a
short period of time and then release it to the surface and stormwater management system.
BBB."Site" means the entire lot, series of lots, or parcels on which a development is located or
proposed to be located, including all contiguous lots or parcels under common ownership.
CCC."Slope" means the degree of deviation of a surface from the horizontal; measured as a
numerical ratio, percent, or in degrees. Expressed as a ratio, the first number is the horizontal
distance (run) and the second is the vertical distance (rise), as 2: 1. A 2:1 slope is a 50 percent
slope. Expressed in degrees, the slope is the angle from the horizontal plane, with a 90 slope
being vertical (maximum) and 45 being a 1:1 or 100 percent slope.
DDD."Small Parcel Erosion and Sediment Control (ESC) Plan" means a plan for the
disturbance of less than one acre and creation of less than 5,000 square feet of impervious surface
and to implement temporary BMPs to control pollution generated during the construction phase,
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primarily for erosion and sediment control and to reduce impacts from developed conditions.
Guidance for preparing a Small Parcel ESC Plan is contained in the Manual.
EEE."SoiI" means the unconsolidated mineral and organic material on the immediate surface of
the earth that serves as a natural medium for the growth of land plants.
FFF."Source control BMP" means a BMP that is intended to prevent pollutants from entering
stormwater. A few examples of source control BMPs are erosion control practices, maintenance
of stormwater facilities, constructing roofs over storage and working areas, and directing wash
water and similar discharges to the sanitary sewer or a dead end sump.
GGG."Stormwater" means that portion of precipitation that does not naturally percolate into the
ground or evaporate, but flows via overland, interflow, channels or pipes into a defined surface
water channel, or a constructed infiltration facility.
HHH."Stormwater drainage system" means constructed and natural features which function
together as a system to collect, convey, channel, hold, inhibit, retain, detain, infiltrate, divert,
treat or filter stormwater.
III. "Stormwater facility" means a constructed component of a stormwater drainage system,
designed or constructed to perform a particular function, or multiple functions, including but not
limited to, pipes, swales, ditches, culverts, street gutters, detention basins, retention basins,
constructed wetlands, infiltration devices, catchbasins, oil/water separators, sediment basins and
modular pavement.
JJJ."Stormwater Management Manual" or "(Manual)" means the Manual adopted by
reference and prepared by Washington State Department of Ecology which contains BMPs to
prevent or reduce pollution.
KKK."Stormwater site plan" means a plan which includes a Temporary Erosion and Sediment
Control (ESC) Plan and/or a Permanent Stormwater Quality Control Plan (PSQCP). For small
sites, this plan is the equivalent of a Small Parcel Erosion and Sediment Control Plan. Guidance
on preparing a Stormwater Site Plan is contained in the Manual.
LLL."Toe of slope" means a point or line of slope in an excavation or cut where the lower
surface changes to horizontal or meets the exiting ground slope.
MMM."Top of slope" means a point or line on the upper surface of a slope where it changes to
horizontal or meets the original surface.
NNN."Treatment BMP" means a BMP that is intended to remove pollutants from stormwater.
A few examples of treatment BMPs are detention ponds, oil/water separators, biofiltration swales
and constructed wetlands.
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O00."Unstable slopes" means those sloping areas of land which have exhibited past and
present history of mass movement of earth.
PPP."Vegetation" means all organic plant life growing on the surface of the earth. Reference
BIMC 16.24.
QQQ."Watershed" means a geographic region within which water drains into a particular river,
stream, or body of water as identified and numbered by the State of Washington Water Resource
Inventory Areas (WRIAs) as defined in Chapter 173-500 WAC.
RRR."Wetlands" means those areas that are inundated or saturated by surface or ground water at
a frequency and duration sufficient to support, (and under normal circumstances do support), a
prevalence of vegetation typically adapted for life in saturated soil conditions, such as swamps,
marshes, bogs, and other similar areas. This definition includes wetlands created, restored or
enhanced as part of a mitigation procedure; it does not include constructed wetlands or the
following surface waters of the State intentionally constructed from sites that are not wetlands:
Irrigation and drainage ditches, grass-lined swales, canals, agricultural detention facilities, farm
ponds, and landscape amenities. Reference BIMC 16.20.
15.20.030 General provisions.
A. Abrogation and greater restrictions. This Chapter is not intended to repeal,
abrogate, or impair any existing regulations, easements, covenants, or deed restrictions.
However, where this Chapter imposes greater restrictions, the provisions of this Chapter shall
prevail.
B. Interpretation. The provisions of this Chapter shall be held as minimum
requirements in their interpretation and application and shall be liberally construed to serve the
purposes of this Chapter.
C. Applicability. When any provision of the Bainbridge Island Municipal Code
conflicts with this Chapter, the provision which provides more environmental protection shall
apply.
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D. Procedures. The Department of Public Works/Engineering Department is authorized
to adopt written procedures for the purpose of carrying out the provisions of this Chapter. Prior
to fulfilling the requirements of this Chapter, the City Engineer or assigns shall not grant any
approval or permission to conduct a regulated activity, including but not limited to, the
following:
1. Building Permits, Commercial or Residential
2. Comprehensive Plan Amendments
3. Conditional Use Permits
4. Final Plats (Short/Long/Large lot)
5. Forest Practices
6. Grading or Clearing Permits
7. Planned Unit Developments
8. Plats
a. Subdivide, preliminary and final (Short/Long/Large lot)
9. Preliminary Plats (short, long, large lot)
10. Reasonable Use Exceptions
11. Right of Way Permits
12. Road approachs
13. Shoreline substantial development permits
14. Shoreline Variance/Shoreline Conditional Use Permits
15. Site Plan Reviews
16. Variances
17. Zone reclassification(Rezones) or;
18. or any subsequently adopted permit or required approval not expressly exempted
by this Chapter.
E. The following agencies may also require a drainage review to assess a site' s impact.
Any requirements imposed by these agencies are separate from the City mandates. It is the
applicants sole responsibility to resolve any conflicting issues that may arise from submittal
reviews.
1. U.S. Army Corps of Engineers
2. Washington State Department of Natural Resources
3. Bremerton Kitsap County Health District
4. Washington State Department of Ecology
5. Washington State Department of Fish and Wildlife
6. Washington State Department of Transportation
F. Regulated activities shall be permitted only after the City Engineer approves a
Stormwater Site Plan which includes one or more of the following as required by this Chapter:
1. Small Parcel Erosion and Sediment Control Plan
2. Large Parcel Erosion and Sediment Control Plan; and
3. Permanent Stormwater Quality Control (PSQC) Plan
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15.20.040 Regulated activities and allowed activities
A. Regulated Activities. Consistent with the minimum requirements contained in this
Chapter, the City Engineer shall approve or disapprove the following activities, unless exempted
in Section B below:
1. New Development
a. Land disturbing activities;
b. Structural development, including construction; installation or expansion
of an existing building or other structure;
c. Creation of new impervious surfaces greater than 800 square feet;
d. Class IV General Forest Practices that are conversions from timber land to
other uses; and
58.17.020 RCW.
e. Subdivision, short subdivision and binding site plans, as defined in Chapter
2. Redevelopment
a. on an already developed site, the creation or addition of impervious
surfaces; structural development including construction, installation or expansion of a building or
other structure; any land disturbing activity, and/or replacement of impervious surface (that is not
part of a routine maintenance activity) and land disturbing activities associated with structural or
impervious redevelopment.
B. Exemptions Commercial agriculture, and Forest Practices regulated under Title 222
WAC, except for Class IV General Forest Practices that are conversions from timber land to
other uses, are exempt from the provisions of this Chapter.
1. Development undertaken by the Washington State Department of Transportation
in State highway rights-of-way are regulated by Chapter 173-270 WAC, the Puget Sound
Highway Runoff Program.
2. All other new development and redevelopment is subject to the minimum
requirements of this Chapter.
15.20.050 General Requirements.
A. Stormwater management manual adopted. The latest edition of Washington State
Department of Ecology's Stormwater Management Manual is hereby adopted by reference and is
hereinafter referred to as the Manual.
B. Stormwater Best Management Practices (BMPs). BMP's are understood and shall be
used to comply with the standards in this Chapter.
1. BMPs shall be used to control pollution from stormwater. BMPs shall be used to
comply with the standards in this Chapter and are found in the Manual. In those instances where
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appropriate, and a BMP is not in the described Manual, experimental BMPs shall be considered.
Experimental BMPs are encouraged as a means of solving problems in a manner not addressed
by the Manual, in an effort to improve stormwater quality technology.
2. Experimental BMPs must be approved in accordance with the approval process
outlined in the Manual.
C. Illicit discharges. Illicit discharges to stormwater drainage systems are prohibited.
Concrete, concrete by-products, vehicle fluids, paint, chemicals or other polluting matter shall
never be permitted to discharge from the construction site to the natural or constructed drainage
system of the City, to Puget Sound, or to adjacent properties. Pollution of the natural and
constructed drainage system of the City is incompatible with RCW 90.48 and is punishable by
fines.
15.20.060 Approval Standards.
A. Small parcel minimum requirements.
1. The following new development standards shall be required to control erosion and
sediment during construction, to permanently stabilize soil exposed during construction, and to
comply with Small Parcel Requirements of this subsection.
2. Compliance shall be demonstrated through the implementation of an approved
Small Parcel Erosion and Sediment Control Plan. The requirements set forth in 15.20.060 A 2. a,
b, and c. of this Chapter and shall be functional and established prior to any land disturbing
activities.
a. Small parcel requirement #1 -- Construction access route. Construction
vehicle access shall be, whenever possible, limited to one route. Access points shall be stabilized
with quarry spall or crushed rock to minimize the tracking of sediment on to public roads.
i. Wherever construction vehicle access routes intersect paved roads,
provisions must be made to minimize the transport of sediment (mud) on to the paved road. If
sediment is transported on to a road surface, the roads shall be cleaned thoroughly at the end of
each day. Sediment shall be removed from roads by shoveling or sweeping.
b. Small parcel requirement #2 -- Stabilization of denuded areas. Soil
stabilization: All exposed soils shall be stabilized by suitable application of BMPs, including but
not limited to, sod or other vegetation, plastic covering, mulching, or application of ground base
on areas to be paved. All BMPs shall be selected, designed and maintained in accordance with
the described Manual. From October 1 through April 30, no soils shall remain exposed for more
than two (2) days. From May 1 through September 30, no soils shall remain exposed for more
than seven (7) days.
c. Small parcel requirement #3 Protection of adjacent properties.
Adjacent properties shall be protected from sediment deposition by appropriate use of vegetative
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buffer strips, sediment barriers or filters, dikes or mulching, or by a combination of these
measures and other appropriate BMPs.
d. Small parcel requirement #4- Maintenance. All erosion and sediment
control BMPs shall be regularly inspected and maintained to ensure continued performance of
their intended function.
e. Small parcel requirement #5- Preservation of natural drainage systems.
Natural drainage patterns shall be maintained, and discharges from the site shall occur at the
natural location, to the maximum extent practicable.
i. Subsurface Water
Outfalls of water collected from subsurface systems (drains, curtain drains, footing drains, etc.)
shall be discharged in a manner not to create impacts to adjacent properties and shall be
discharged at a point no closer than ten (10) feet to the property line.
f. Small parcel requirement #6 -- Removal of temporary BMPs. All
temporary erosion and sediment control BMPs shall be removed within 30 days after final site
stabilization is achieved or after the temporary BMPs are no longer needed. Disturbed soil areas
resulting from removal of erosion controls shall be permanently stabilized.
g. Small parcel requirement #7- Other BMPs. Other appropriate BMP' s to
mitigate the effects of increased runoff will be required if the base requirements do not have
sufficient protection or controls then the developers shall provide a system for stormwater
control.
B. Large development minimum requirements
1. New development
a. All new development that includes the creation or addition of 5,000 square
feet, or greater, of new impervious surface area, and/or land disturbing activity of ONE ACRE
OR GREATER, shall comply with Minimum Requirements # 1 through # 12 of the Erosion and
Sediment Control Minimum Requirement section.
i. Compliance shall be demonstrated through the implementation of an
approved Stormwater Site Plan consisting of a Large Parcel ESC Plan and a PSQC Plan, as
appropriate.
b. All new development that includes the creation or addition of 5,000 square
feet, or greater, of new impervious surface area, and land disturbing activity of LESS THAN
ONE ACRE, shall comply with ESC Minimum Requirements #2 through # 12 and the Small
Parcel Minimum Requirements found in 15.20,060 A.
i. Compliance shall be demonstrated through the implementation of an
approved Stormwater Site Plan that includes a Small Parcel Erosion and Sediment Control Plan
and a PSQC Plan.
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2. Redevelopment
a. Where redevelopment of greater than 5,000 square feet occurs: New
Development ESC Minimum Requirements # 1 through # 11 shall apply to that portion of the site
that is being redeveloped, and source control BMPs shall be applied to the entire site, including
adjoining parcels if they are part of the project.
b. In addition to the above requirements, where one or more of the following
conditions apply, a stormwater management plan shall be prepared that includes a schedule for
implementing the minimum requirements to the maximum extent practicable, for the entire site,
including adjoining parcels if they are part of the project. An adopted and implemented basin
plan (Minimum Requirement #9) may be used to develop redevelopment requirements that are
tailored to a specific basin.
i. Existing sites greater than one ( 1 ) acre in size with fifty percent (50%) or
more impervious surface.
ii. Sites that discharge to a receiving water that has a documented water
quality problem. Subject to local priorities, a documented water quality problem includes, but is
not limited to water bodies:
-Listed in reports required under section 305(b) of the Clean Water Act,
and designated as not supporting beneficial uses;
-Listed under section 304(1)( 1 )(A)(i),304(1)(1 )(A)(ii), or 304(1)(1 )(B) of
the Clean Water Act as not expected to meet water quality standards or water quality goals; and
-Listed in Washington State's Nonpoint Source Assessment required under
section 319(a) of the Clean Water Act that, without additional action to control nonpoint sources
of pollution cannot reasonably be expected to attain or maintain water quality standards.
iii. Sites where the need for additional stormwater control measures have
been identified through a basin plan, the watershed ranking process under Chapter 400-12 WAC,
or through Growth Management Act planning.
C. Erosion and sediment control minimum requirements
1. Minimum requirement # 1 --New and Redevelopment. All new development
and redevelopment that includes land disturbing activities of GREATER THAN ONE OR
EQUAL TO (1) acre shall comply with the following Erosion and Sediment Control
Requirements. Compliance with the Erosion and Sediment Control Requirements shall be
demonstrated through implementation of an approved Large Parcel Erosion and Sediment
Control Plan.
a. Erosion and sediment control requirement #1 -- Stabilization and
sediment trapping. All exposed and unworked soils shall be stabilized by suitable application
of BMPs. From October 1 through April 30, no soils shall remain unstabilized for more than two
(2) days. From May 1 through September 30, no soils shall remain unstabilized for more than
seven (7) days. Prior to leaving the site, stormwater runoff shall pass through a sediment pond or
sediment trap, or other appropriate BMPs.
b. Erosion and sediment control requirement #2 --Delineate clearing and
easement limits. In the field, mark clearing limits and/or any easements, setbacks,
sensitive/critical areas and their buffers, trees and drainage courses.
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c. Erosion and sediment control requirement #3 Protection of adjacent
properties. Properties adjacent to the project site shall be protected from sediment deposition.
d. Erosion and sediment control requirement #4 -- Timing and stabilization
of sediment trapping measures. Sediment ponds and traps, perimeter dikes, sediment barriers,
and other B MPs intended to trap sediment on-site shall be constructed as a first step in grading.
These BMPs shall be functional before land disturbing activities take place. Earthen structures
such as dams, dikes, and diversions shall be seeded and mulched according to the timing
indicated in Erosion and Sediment Control Requirement # 1.
e. Erosion and sediment control requirement #5 -- Cut and fill slopes. Cut
and fill slopes shall be designed and constructed in a manner that will minimize erosion. In
addition, slopes shall be stabilized in accordance with Erosion and Sediment Control
Requirement # 1.
f. Erosion and sediment control requirement #6 -- Controlling off-site
erosion. Properties and waterways downstream from development sites shall be protected from
erosion due to increases in the volume, velocity, and peak flow rate of stormwater runoff from
the project site.
g. Erosion and sediment control requirement #7- Stabilization of
temporary conveyance channels and outlets. All temporary on-site conveyance channels shall
be designed, constructed and stabilized to prevent erosion from the expected velocity of flow
from a 2-year, 24-hour frequency storm for the developed condition. Stabilization adequate to
prevent erosion of outlets, adjacent streambanks, slopes and downstream reaches shall be
provided at the outlets of all conveyance systems.
h. Erosion and sediment control requirement #8 -- Storm drain inlet
protection. All storm drain inlets made operable during construction shall be protected so that
stormwater runoff shall not enter the conveyance system without first being filtered or otherwise
treated to remove sediment.
i. Erosion and sediment control requirement #9- Underground utility
construction. The construction of underground utility lines shall be subject to the following
criteria:
i. Where feasible, no more than 500 feet of trench shall be opened at one
time.
ii. Where consistent with safety and space considerations, excavated material
shall be placed on the uphill side of trenches.
iii. Trench dewatering devices shall discharge into a sediment trap or
sediment pond.
j. Erosion and sediment control requirement #10 -- Construction access
routes. Wherever construction vehicle access routes intersect paved roads, provisions must be
made to minimize the transport of sediment (mud) on to the paved road. If sediment is
transported on to a road surface, the roads shall be cleaned thoroughly at the end of each day.
Sediment shall be removed from roads by shoveling or sweeping and be transported to a
controlled sediment disposal area. Street washing shall be allowed only after sediment is
removed in this manner.
k. Erosion and sediment control requirement #11 -- Removal of temporary
BMPs. All temporary erosion and sediment control BMPs shall be removed within 30 days after
final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped
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sediment shall be removed or stabilized on site. Disturbed soil areas resulting from removal
shall be permanently stabilized.
1. Erosion and sediment control requirement #12 -- Dewatering
construction sites. Dewatering devices shall discharge into a sediment trap or sediment pond.
m. Erosion and sediment control requirement #13 -- Control of pollutants
other than sediment on construction sites. All pollutants other than sediment that occur on-
site during construction shall be handled and disposed of in a manner that does not cause
contamination of stormwater.
n. Erosion and sediment control requirement #14 Maintenance.
All temporary and permanent erosion and sediment control BMPs shall be maintained and
repaired as needed to assure continued performance of their intended function. All maintenance
and repair shall be conducted in accordance with an approved manual.
o. Erosion and sediment control requirement #15- Financial liability.
Performance bonding, or other appropriate financial instruments, shall be required for all projects
to ensure compliance with the approved erosion and sediment control plan.
2. Minimum requirement #2 -- Preservation of natural drainage systems
Natural drainage patterns shall be maintained, and discharges from the site shall occur at the
natural location, to the maximum extent practicable.
a. Subsurface Water
Outfalls of water collected from subsurface systems (drains, curtain drains, footing drains, etc.)
shall be discharged in a manner not to create impacts to adjacent properties and shall be
discharged at a point no closer than ten (10) feet to the property line.
3. Minimum requirement #3 -- Source control of pollution
a. Source control BMPs shall be applied to all projects to the maximum extent
practicable. Source control BMPs shall be selected, designed, and maintained according to the
adopted Manual.
b. An adopted and implemented basin plan (Minimum Requirement #9) may be
used to develop source control requirements that are tailored to a specific basin, however, in all
circumstances, source control BMPs shall be required for all sites.
4. Minimum requirement #4 -- Runoff treatment BMPs. All projects shall
provide treatment of stormwater. Treatment BMPs shall be sized to capture and treat the water
quality design storm, defined as the 6-month, 24-hour return period storm. The first priority for
treatment shall be to infiltrate as much as possible of the water quality design storm, only if site
conditions are appropriate and ground water quality will not be impaired. Direct discharge of
untreated stormwater to ground water is prohibited. All treatment BMPs shall be selected,
designed, and maintained according to the Manual.
a. Stormwater treatment BMPs shall not be built within a vegetated buffer or
buffers for streams and wetlands.
b. An adopted and implemented basin plan (Minimum Requirement #9) may be
used to develop runoff treatment requirements that are tailored to a specific basin.
c. Ponds developed for detention or water quality shall be designed to work
within the existing contours and avoid rigid geometric shapes.
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5. Minimum requirement #5- Streambank erosion control. The requirement
below applies only to situations where stormwater runoff is discharged directly or indirectly to a
stream, and must be met in addition to meeting the requirements in Minimum Requirement #4 -
Runoff Treatment BMPs.
a. Stormwater discharges to streams shall control streambank erosion by limiting
the peak rate of runoff from individual development sites to fifty percent (50%) of the existing
condition 2-year, 24-hour design storm while maintaining the existing condition peak runoff rate
for the 10-year, and 100-year, 24-hour design storms. As the first priority, streambank erosion
control BMPs shall utilize infiltration to the fullest extent practicable, only if site conditions are
appropriate and ground water quality is protected. Streambank erosion control BMPs shall be
selected, designed, and maintained according to the adopted Manual.
b. Stormwater treatment BMPs shall not be built within a natural vegetated
buffer or the buffers for streams and wetlands.
c. An adopted and implemented basin plan (Basin Planning Minimum
Requirement #9) may be used to develop streambank erosion control requirements that are
tailored to a specific basin.
6. Minimum requirement #6 -- Wetlands. The requirements below apply only to
situations where stormwater discharges directly or indirectly through a conveyance system into a
wetland, and must be met in addition to meeting the requirements in Minimum Requirement #4,
Runoff Treatment BMPs.
a. Stormwater discharges to wetlands must be controlled and treated to the extent
necessary to meet the State Water Quality Standards, Chapter. 173-201 WAC, or Ground Water
Quality Standards, Chapter 173-200 WAC, as appropriate.
b. Discharges to wetlands shall maintain the hydroperiod and flows of existing
site conditions to the extent necessary to protect the characteristic uses of the wetland. Prior to
discharging to a wetland, alternative discharge locations shall be evaluated, and natural water
storage and infiltration opportunities outside the wetland shall be maximized.
c. Created wetlands that are intended to mitigate for loss of wetland acreage,
function and value shall not be designed to also treat stormwater.
d. In order for constructed wetlands to be considered treatment systems, they
must be constructed on sites that are not wetlands and they must be managed for stormwater
treatment. If these systems are not managed and maintained in accordance with an approved
manual for a period exceeding three years these systems may no longer be considered
constructed wetlands. Discharges from constructed wetlands to waters of the State (including
discharges to natural wetlands) are regulated under Chapter. 90.48 RCW, Chapter. 173-201
WAC, and Chapter. 173-200 WAC.
e. Stormwater treatment BMPs shall not be built within a natural vegetated
buffer or the buffers for streams and wetlands. An adopted and implemented Basin Plan
(Minimum Requirement #9) may be used to develop requirements for wetlands that are tailored
to a specific basin.
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7. Minimum requirement #7- Water quality sensitive areas. Where local
governments determine that the minimum requirements do not provide adequate protection of
water quality sensitive areas, either on-site or within the basin, more stringent controls shall be
required to protect water quality.
a. Stormwater treatment BMPs shall not be built within a natural vegetated
buffer or the buffers for streams and wetlands.
b. An adopted and implemented Basin Plan (Minimum Requirement #9) may be
used to develop requirements for water quality sensitive areas that are tailored to a specific basin.
8. Minimum requirement #8- Off-site analysis and mitigation. All
development projects shall conduct an analysis of off-site water quality impacts resulting from
the project and shall mitigate these impacts. The analysis shall extend a minimum of one-fourth
of a mile downstream from the project. The existing or potential impacts to be evaluated and
mitigated shall include, at a minimum, but not be limited to:
a. Excessive sedimentation
b. Streambank erosion
c. Discharges to ground water contributing or recharge zones
d. Violations of water quality standards
e. Spills and discharges of priority pollutants
9. Minimum requirement #9- Basin planning. Adopted and implemented
watershed-based basin plans may be used to modify any or all of the Minimum Requirements
required in this section, provided that, the level of protection for surface or ground water
achieved by the basin plan will equal or exceed that which would be achieved by the minimum
requirements in the absence of a basin plan. Basin plans shall evaluate and include, as necessary,
rctrofitting of BMPs for existing development and/or rcdevelopment in order to achieve
watershed-wide pollutant reduction goals. Standards developed from basin plans shall not
modify any of the above requirements until the basin plan is formally adopted and fully
implemented by the City. Basin plans shall be developed according to an approved manual.
10. Minimum requirement #10--Operation and maintenance An operation
and maintenance schedule shall be provided for all proposed stormwater facilities and BMPs, and
the party (or parties) responsible for maintenance and operation shall be identified.
11. Minimum requirement #11 Financial liability. Performance bonding or
other appropriate financial instruments shall be required for all projects to ensure compliance
with these standards.
12. Variances. Variances to Minimum Requirements # 1 through # 11 may be
granted in accordance with BIMC 15.20.090.
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15.20.070 Administration
A. Review and approval
1. The Director may approve, conditionally approve or deny an application for
activities regulated by this Chapter.
2. When the Director is required to review any proposed regulated activity for
compliance with this Chapter, fees shall be imposed as established by resolution.
B. Enforcement authority. The enforcement of this Chapter is administered in BIMC
1.26.
C. Inspection
1. All activities regulated by this Chapter, except those exempt in Section 15.20.040
B, shall be inspected by the Director or his/her assigns. The Director shall inspect projects at
various stages of the work that require approval, to determine that adequate control is being
exercised. Stages of work requiring inspection include, but are not limited to, preconstruction;
installation of BMPs, land disturbing activities, installation of utilities, permanent stormwater
control facilities, retaining walls and completion of project. When required by the Director, a
special inspection and/or testing shall be performed.
15.20.080 Enforcement
A. General. Enforcement action shall be in accordance with this Chapter whenever a
person has violated any provision of this Chapter. Enforcement action and the severity of any
penalty shall be as provided for in BIMC Chapter 1.26.
1. Stop work order. The Director or assign or appropriate City Official shall have
the authority to serve a person a stop work order pursuant to Chapter 1.26 BIMC if an action is
being undertaken in violation of this Chapter. If a portion of a project is in violation of this
Chapter, the Director may issue a stop work order for the entire project.
B. Civil penalty. A person who fails to comply with the requirements of this Chapter,
who fails to conform to the terms of an approval or order iggued, who undertakeg new
development without first obtaining City approval, or who fails to comply with a stop work order
issued under these regulations shall be subject to a civil penalty as provided in Chapter 1.26.090
BIMC.
15.20.090 Exceptions and Appeals
A. After a public hearing, the Hearing Examiner may grant an exception from the
requirements of this Chapter in accordance with the procedures of BIMC 2.16. In granting any
exception, the Hearing Examiner may prescribe conditions that are deemed necessary or
desirable for the public interest.
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B. Findings of fact. Exceptions to Minimum Requirements # 1 through # 11 may be
granted prior to permit approval and construction. An exception may be granted following a
public hearing, provided that a written finding of fact is prepared, that addresses the following:
1. The exception provides equivalent environmental protection and is in the
overriding public interest; and that the objectives of safety, function, environmental protection
and facility maintenance, based upon sound engineering are fully met;
2. That there are special physical circumstances or conditions affecting the
property such that the strict application of these provisions would deprive the applicant of all
reasonable use of the parcel of land in question, and every effort to find creative ways to meet the
intent of the minimum standards has been made;
3. That the granting of the exception will not be detrimental to the public health
and welfare, nor injurious to other properties in the vicinity and/or downstream, and to the
quality of waters of the State; and
4. The exception is the least possible exception that could be granted to comply
with the intent of the Minimum Requirements of this Chapter.
C. Prior approval. Any exception shall be approved prior to permit approval and
construction.
D. Duration of exception. Exceptions granted shall be valid for 2 years, unless granted
for a shorter period.
E. Right of appeal. All actions of the Hearing Examiner shall be final and conclusive,
unless an appeal of the Hearing Examiner' s decision is filed pursuant to BIMC 2.16.140.
15.20.100 Severability
A. If any provision of this Chapter or its application to any person, entity, or
circumstance is held invalid, the remainder of this Chapter or the application of the provision to
other persons, entities, or circumstances shall not be affected.
Section 2. This ordinance shall take effect and be in force five days from and after its
passage, approval and publication as provided by law.
PASSED by the City Council this 4th
day of February, 1999.
APPROVED by the Mayor this 5th
day of February, 1999.
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ATTEST/AUTHENTI C ATE:
Susan P. Kasper, City Clerk
APPROVED AS TO FORM:
Rod P. Kasegma, City Attorney
FILED WITH THE CITY CLERK:
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