680 Model Stormwater ManagementCITY OF YELM
Model Stormwater Management Ordinance
Ordinance No.
Model Stormwater Management Ordinance
CITY OF YELM
Model Stormwater Management Ordinance
Ordinance No.
Model Stormwater Management Ordinance
MODEL STORMWATER MANAGEMENT ORDINANCE
Table of Contents
Page
INTRODUCTION............................ ..............................1
SECTION 1: FINDINGS OF FACT, NEED AND PURPOSE ......................... 1
1.1 Findings of Fact .................. ............................... 1
1.2 Need ........................... ..............................2
1.3 Purpose ......................... ..............................3
SECTION 2: DEFINITIONS .................... ..............................3
SECTION 3: GENERAL PROVISIONS .......... ............................... 11
3.1 Abrogation and greater restrictions ... ............................... 11
3.2 Interpretation ................... ............................... 11
SECTION 4: APPLICABILITY .................. .............................11
SECTION 5: REGULATED ACTIVITIES AND ALLOWED ACTIVITIES ............. 12
5.1 Regulated activities ............... ............................... 12
5.2 Exemptions ...................... .............................12
SECTION 6: GENERAL REQUIREMENTS ...... ............................... 13
6.1 Stormwater management manual adopted ............................. 13
6.2 Stormwater best management practices (BMPs) ........................ 13
6.3 Illicit discharges ................. ............................... 13
SECTION 7: APPROVAL STANDARDS ........ ...............................
13
7.1 Small
parcel minimum requirements
.. ...............................
13
7.1.1
Small parcel requirement #1
— Construction access route ...........
13
7.1.2
Small parcel requirement #2
— Stabilization of denuded areas .......
14
7.1.3
Small parcel requirement #3
— Protection of adjacent properties .....
14
7.1.4
Small parcel requirement #4
— Maintenance .....................
14
7.1.5
Small parcel requirement #5
— Other BMPs .....................
14
7.2 Large
development minimum requirements ............................
14
7.2.1
New development ..........
...............................
14
7.2.2
Redevelopment ............
...............................
15
7.2.3
Minimum requirement #1 —
Erosion and sediment control ..........
15
7.2.4
Minimum requirement #2 —
Preservation of natural drainage
systems....................
.............................18
7.2.5
Minimum requirement #3 —
Source control of pollution ............
18
7.2.6
Minimum requirement #4 —
Runoff treatment BMPs ..............
18
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7.2.7 Minimum requirement #5 -
7.2.8 Minimum requirement #6 -
7.2.9 Minimum requirement #7 -
7.2.10 Minimum requirement #8 -
7.2.11 Minimum requirement #9 -
7.2.12 Minimum requirement #10
7.2.13 Minimum requirement #11
7.2.14 Exceptions ...........
Streambank erosion control ........... 19
Wetlands ......................... 19
Water quality sensitive areas ........... 20
Off -site analysis and mitigation ......... 20
Basin planning ..................... 21
- Operation and maintenance .......... 21
- Financial liability ................... 21
.... .............................21
SECTION 8: ADMINISTRATION .............. ............................... 21
8.1 Director ......................... .............................21
8.2 Review and approval ............. ............................... 21
8.3 Enforcement authority ............ ............................... 22
8.4 Inspection ........................ .............................22
SECTION 9: ENFORCEMENT ................ ............................... 22
9.1 General .......................... .............................22
9.2 Stop work order ................. ............................... 22
9.3 Penalties and Procedures .......... ............................... 23
SECTION 10: EXCEPTIONS .................. ............................... 23
10.1 Authority of City Council .......... ............................... 23
10.2 Findings of Fact ................. ............................... 23
10.3 Prior approval .................... .............................24
10.4 Duration of exception ............. ............................... 24
10.5 Right of appeal .................. ............................... 24
SECTION 11: SEVERABILITY ................ ............................... 24
ii Model Stormwater Management Ordinance
MODEL STORMWATER MANAGEMENT ORDINANCE
INTRODUCTION
WHEREAS, The Washington State Department of Ecology ( "Ecology ") has established minimum
requirements that must be met in order to satisfy requirements under the Puget Sound Stormwater
Program; and
WHEREAS, Ecology has provided a Model Stormwater Maintenance Ordinance and a Model
Stormwater Management Ordinance for adoption or adaptation by local government units to assist
them in satisfying those requirements; and
WHEREAS, the MODEL STORMWATER MANAGEMENT ORDINANCE has been deemed by
the Yehn City Council to be suitable for incorporation into the Yelm Municipal Code ( "YMC ") with
minor changes for conformity with existing policies and provisions of the YMC;
NOW THEREFORE, The City Council of the City of Yelm does ORDAIN AS FOLLOWS:
A new chapter is added to the Yelm Municipal Code, entitled Model Stormwater Management
Ordinance, as follows:
SECTION 1: FINDINGS OF FACT, NEED AND PURPOSE
1.1 Findings of Fact
The City Council of the City of Yelm (which may be referred to herein as the "City" or "Yelm")
hereby finds that:
A. Stormwater pollution is a problem associated with land utilization and development and the
common occurrence of potential pollutants such as pesticides, fertilizers, petroleum products,
pet wastes and numerous others.
Land utilization is also known to increase both the volume and duration of peak flows. The
resulting erosion, scouring, and deposition of sediment affect the ecological balance in the
stream.
Sedimentation and stormwater pollution cause diversity of species to decrease and allows
more tolerant (and usually less desirable) species to remain.
Stormwater pollution can cause or contribute to closures of shellfish beds and swimming
beaches and other restrictions on public use of the waters within Thurston County.
B. An expanding population and increased development of land have led to:
Model Stormwater Management Ordinance
water quality degradation through discharge of nutrients, metals, oil and grease, toxic
materials, and other detrimental substances including, without limitation, insect and weed
control compounds;
drainage and storm and surface water runoff problems within the City; and
safety hazards to both lives and property posed by uncontrolled water runoff on streets and
highways.
C. Continuation of present stormwater management practices, to the extent that they exist, will
lead to water quality degradation, erosion, property damage, and endanger the health and
safety of the inhabitants of the City.
D. In the future such 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.
E. Stormwater quality and quantity controls can be achieved when land is developed or
redeveloped by implementing appropriate best management practices (BMPs).
F. Best management practices can be expected to perform as intended only when properly
designed, constructed and maintained.
1.2 Need
The City Council finds that this chapter is necessary in order to:
A. Minimize or eliminate water quality degradation.
B. Prevent erosion and sedimentation in creeks, streams, ponds, lakes and other water bodies.
C. Protect property owners adjacent to existing and developing lands from increased runoff rates
which could cause erosion of abutting property.
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 surface water, ground
water and sediment.
G. Ensure the safety of City roads and rights -of -way.
2 Model Stormwater Management Ordinance
H. Decrease stormwater- related damage to public and private property from existing and future
runoff.
I. To protect the health, safety and welfare of the inhabitants of the City.
1.3 Purpose
The provisions of this ordinance are intended to guide and advise all who conduct new development
or redevelopment within the City of Yelm. The provisions of this ordinance establish the minimum
level of compliance which must be met to permit a property to be developed or redeveloped within
Yelm.
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 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 those downstream;
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 which will preserve,
replace or enhance, to the maximum extent practicable, existing vegetation to preserve and
enhance the natural qualities of lands, wetlands and water bodies.
SECTION 2: DEFINITIONS
For the purposes of this chapter, the following definitions shall apply:
3 Model Stormwater Management Ordinance
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 stormwater
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.
F. "Bench" means a relatively level step excavated into earth material on which fill is to be
placed.
G. "Best Management Practice" or `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. "Civil engineer" means a professional engineer licensed in the State of Washington in Civil
Engineering who is experienced and knowledgeable in the practice of soils engineering.
"Civil engineering" means the application of the knowledge of the forces of nature, principles
of mechanics and the properties of materials to the evaluation, design and construction of civil
works for the beneficial uses of mankind.
J. "Clearing" means the destruction and removal of vegetation by manual, mechanical, or
chemical methods.
K. "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 lain 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 or irrigation ditches, laterals, canals, or
drainage ditches related to an existing and ongoing agricultural activity.
L. "Compaction" means densification of a fill by mechanical means.
M. "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
4 Model Stormwater Management Ordinance
areas, frequently flooded area, geologically hazardous area, including unstable slopes, and
associated areas and ecosystems.
N. "Design Storm" means a prescribed hyetograph and total precipitation amount (for a specific
duration recurrence frequency) used to estimate runoff for a hypothetical storm of interest or
concern 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.)
O. "Detention" means the release of stormwater runoff from the site at a slower rate than it is
collected by the stormwater facility system, the difference being held in temporary storage.
P. "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.
Q. "Director" means the Director of Public Works of the City of Yelm.
R. "Drainage basin" means a geographic and hydrologic subunit of a watershed.
S. "Earth material" means any rock, natural soil or fill and /or any combination thereof.
T. "Ecology" means the Washington State Department of Ecology.
U. "Engineering geologist" means a geologist experienced and knowledgeable in engineering
geology.
V. "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.
W. "Erosion" means the wearing away of the land surface by running water, wind, ice, or other
geological agents, including such processes as gravitational creep. Detachment and
movement of soil or rock fragments by water, wind, ice, or gravity.
X. "Excavation" means the mechanical removal of earth material.
Y. "Existing site conditions" means:
(1) For developed sites with stormwater facilities that have been constructed to meet the
standards in the Minimum Requirements of this Manual, existing site conditions shall
mean the existing conditions on the site.
5 Model Stormwater Management Ordinance
(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
the City's adoption of a stormwater management program. 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.
Z. "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.
AA. "Fill" means a deposit of earth material placed by artificial means.
BB. "Forest practice" means any activity conducted on or directly pertaining to forest land and
relating to growing, harvesting, or processing timber, including but not limited to:
(1) Road and trail construction;
(2) Harvesting, final and intermediate;
(3) Pre - commercial thinning;
(4) Reforestation;
(5) Fertilization;
(6) Prevention and suppression of diseases and insects;
(7) Salvage of trees;
(8) Brush control.
CC. "Frequently flooded areas" means the 100 -year floodplain designations of the Federal
Emergency Management Agency and the National Flood Insurance Program.
DD. "Geologically hazardous areas" means areas that because of their susceptibility to erosion,
sliding, earthquake or other geological events, are not suited to the siting of commercial,
residential or industrial development consistent with public health or safety concerns.
EE. "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; 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.
6 Model Stormwater Management Ordinance
(3) Finish grade. The final grade of the site which conforms to the approved plan.
FF. "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.
GG. [To] "Grade" means to finish the surface of a canal bed, roadbed, top of embankment or
bottom of excavation.
HH. "Ground water" means water in a saturated zone or stratum beneath the surface of land or a
surface water body.
II. "Hydroperiod" means the seasonal occurrence of flooding and /or soil saturation; it
encompasses depth, frequency, duration, and seasonal pattern of inundation.
H. "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
impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways,
parking lots or storage areas, 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.
KK. "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.
LL. "Interflow" means that portion of precipitation that infiltrates into the soil and moves laterally
through the upper soil horizons until intercepted by a stream channel or until it returns to the
surface for example, in a wetland, spring or seep.
MM. "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.
NN. "Large Parcel Erosion and Sediment Control Plan" or "Large Parcel ESC Plan" means a plan
to implement BMPs to control pollution generated during land disturbing activity. Guidance
for preparing a Large Parcel ESC Plan is contained in the Manual.
00. "Mitigation" means, in the following order of preference:
7 Model Stormwater Management Ordinance
(1) Avoiding the impact altogether by not taking a certain action or part of an 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; and
(5) Compensation for the impact by replacing, enhancing, or providing substitute
resources or environments.
PP. "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.
QQ. "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; 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.
RR. "Owner" and "Person" have the same meanings as in YMC 9.44.010, and Chapter 1.04 YMC;
or any cooperative, and also include any agency or unit of state or local government.
SS. "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 Small Parcel Erosion and Sediment Control Plan. Guidance on preparing
a PSQC Plan is contained in the Manual.
TT. "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 liquid, 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.
UU. "Redevelopment" means, on an already developed site, the creation or addition of impervious
surfaces, structural development including construction, installation or expansion of a building
8 Model Stormwater Management Ordinance
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.
W. "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. 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.
WW. "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.
XX. "Site" means the portion of a piece of property which is directly subject to development.
YY. "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.
ZZ. "Small Parcel Erosion and Sediment Control Plan" or "Small Parcel ESC Plan" means a plan
for small sites to implement temporary BMPs to control pollution generated during the
construction phase only, primarily erosion and sediment. Guidance for preparing a Small
Parcel ESC Plan is contained in the Manual.
AAA. "Soil' 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.
BBB. "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.
CCC. "Stormwater" means that portion of precipitation that does not naturally percolate into the
ground or evaporate, but flows via overland flow, interflow, channels or pipes into a defined
surface water channel, or a constructed infiltration facility.
DDD. "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.
9 Model Stormwater Management Ordinance
EEE. "Stormwater facility" means a constructed component of a stormwater drainage system,
designed or constructed to perform a particular function, or multiple functions. Stormwater
facilities include, but are 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.
FFF. "Stormwater Management Manual' or "Manual' means the Manual adopted by reference and
prepared by Ecology that contains BMPs to prevent or reduce pollution [or a technically
equivalent manual approved by Ecology].
GGG. "Stormwater Site Plan" means a plan which includes an 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.
HHH. "Toe of slope" means a point or he of slope in an excavation or cut where the lower surface
changes to horizontal or meets the existing ground slope.
III. "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.
JJJ. "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.
KKK. "Unstable slopes" means those sloping areas of land which have in the past exhibited, are
currently exhibiting, or will likely in the future exhibit, mass movement of earth.
LLL. "Water body" means surface waters including rivers, streams, lakes, marine waters, estuaries,
and wetlands.
MMM. "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.
NNN. "Wetlands" means those areas that are inundated or saturated by surface or ground water at
a frequency and duration sufficient to support, and that under normal circumstances do
support, a prevalence of vegetation typically adapted for life in saturated soil conditions.
Wetlands generally include swamps, marshes, bogs, and similar areas. This includes wetlands
created, restored or enhanced as part of a mitigation procedure. This 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.
000. "Vegetation" means all organic plant life growing on the surface of the earth.
10 Model Stormwater Management Ordinance
SECTION 3: GENERAL PROVISIONS
3.1 Abrogation and greater restrictions
It is not intended that his chapter 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 unless prohibited by law.
3.2 Interpretation
The provisions of this chapter shall be held to be minimum requirements in their interpretation and
application and shall be liberally construed to serve the purposes of this chapter.
SECTION 4: APPLICABILITY
4.1 When any provision of any other chapter of the Yelm Municipal code ( "YMC ") conflicts with
this chapter, that which provides more environmental protection shall apply unless specifically
provided otherwise in this chapter.
4.2 The Director is authorized to adopt written procedures for the purpose of carrying out the
provisions of this chapter subject to approval by the City Council. Prior to fulfilling the requirements
of this chapter, the City shall not grant any approval or permission to conduct a regulated activity
including but not limited to the following:
building permit, commercial or residential; binding site plan; conditional use permit; franchise
right -of -way construction permit; grading and clearing permit; master plan development;
planned unit development; right -of -way permit; unclassified use permit; variance; zone
reclassification; subdivision; short subdivision; special use permit; utility and other use permit;
or any subsequently adopted permit or required approval not expressly exempted by this
chapter.
4.3 Regulated activities shall be conducted only after the City approves a Stormwater Site Plan
which includes one or more of the following as required by this chapter:
A. Small Parcel Erosion and Sediment Control Plan
B. Large Parcel Erosion and Sediment Control Plan
C. Permanent Stormwater Quality Control (PSQC) Plan
11 Model Stormwater Management Ordinance
SECTION 5: REGULATED ACTIVITIES AND ALLOWED ACTIVITIES
5.1 Regulated activities
Consistent with the minimum requirements contained in this chapter, the City shall approve or
disapprove the following activities, unless exempted in Section 5.2 below:
A. New Development
(1) land disturbing activities;
(2) structural development, including construction; installation or expansion of a building
or other structure;
(3) creation of impervious surfaces;
(4) Class IV general forest practices that are conversions from timber land to other uses;
(5) subdivision, short subdivision and binding site plans, as defined in RCW 58.17.020.
B. Redevelopment
(1) 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, 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.
5.2 Exemptions
A. 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.
B. Development undertaken by the Washington State Department of Transportation in state
highway rights -of -way is regulated by Chapter 173 -270 WAC, the Puget Sound Highway
Runoff Program.
C. All other new development and redevelopment is subject to the minimum requirements of this
chapter.
12 Model Stormwater Management Ordinance
SECTION 6: GENERAL REQUIREMENTS
6,1 Stormwater management manual adopted
The latest edition of Ecology's Stormwater Management Manual is hereby adopted by reference and
is hereinafter referred to as the Manual.
2 Stormwater best management practices (BMPs)
A. General: BMPs shall be used to control pollution from stormwater. BMPs shall be used to
comply with the standards of this Ordinance. BMPs are described in the Manual.
B. Experimental BMPs: In those instances where appropriate BMPs are not in the Manual,
experimental BMPs should 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. Experimental BMPs must be approved in accordance with
the approval process outlined in the Manual.
6.3 Illicit discharges
Illicit discharges to stormwater drainage systems are prohibited.
SECTION 7: APPROVAL STANDARDS
7.1 Small parcel minimum requirements
The following new developments shall be required to control erosion and sediment during
construction, to permanently stabilize soil exposed during construction, to comply with small Parcel
Requirements 1 through 5 below:
A. Individual, detached, single family residences and duplexes.
B. Creation or addition of less than 5,000 square feet of impervious surface area.
C. Land disturbing activities of less than one (1) acre.
Compliance shall be demonstrated through the implementation of an approved Small Parcel Erosion
and Sediment Control Plan.
7.1.1 Small parcel requirement 91 — 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 onto
public roads.
13 Model Stormwater Management Ordinance
7.1.2 Small parcel requirement #2 — Stabilization of denuded ar
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 an approved 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.
T1.3 Small parcel requirement 43 — Protection of adjacent properties
Adjacent properties shall be protected from sediment deposition by appropriate use of
vegetative buffer strips, sediment barriers or filters, dikes or mulching, or by a combination
of these measures and other appropriate BMPs.
7.1.4 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.
7.1,5 Small parcel requirement #5 — Other BMPs
As required by the local plan approval authority, other appropriate BMPs to mitigate the
effects of increased runoff shall be applied.
T2 Large development minimum requirements
7.2.1 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 Requirement Nos. 1 through 11 in Sections
7.2.3 through 7.2.13.
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 Minimum Requirement Nos. 2 through 11 in Sections 7.2.4
through 7.2.13 and the Small Parcel Minimum Requirements found in Section 7.1
above.
14 Model Stormwater Management Ordinance
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.
This section does not apply to the construction of individual, detached, single family
residences and duplexes. Those types of new development are included in the Small parcel
Minimum Requirements.
7.2.2 Redevelopment
A. Where redevelopment of —> 5,000 square feet occurs:
New development minimum requirement nos. 1 through 11 in Sections 7.2.3 through
7.2.13, shall apply to that portion of the site that is being redeveloped, nn 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
ne tine 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.
Existing sites greater than one (1) acre in size with fifty percent (50 %) or
more impervious surface.
2. 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 303(d) of the Clean Water Act, and designated as not supporting
beneficial uses.
3. Sites where the need for additional stormwater control measures has been
identified through a basin plan, the watershed ranking process under Ch. 400-
12 WAC, or through Growth Management Act planning.
7.2.3 Minimum requirement #1 — Erosion and sediment control
All new development and redevelopment that includes land disturbing activities of> one (1)
acre shall comply with Erosion and Sediment Control Requirements 1 through 14, below.
Compliance with the Erosion and Sediment Control Requirements shall be demonstrated
through implementation of an approved Large Parcel Erosion and Sediment Control Plan.
15 Model Stormwater Management Ordinance
All new development and redevelopment that includes land disturbing activities of> one (1)
acre shall comply with the Small Parcel minimum requirements found in Section 7. 1, above.
Compliance with the small parcel requirements shall be demonstrated through implementation
of a Small Parcel Erosion and Sediment Control Plan.
The following erosion and sediment control requirements shall be met:
A. Erosion and sediment control requirement 41: Stabilization and sediment trapping
All exposed and unworked soils shall be stabilized by suitable application of BMPs.
From October 1 to April 30, no soils shall remain unstabilized for more than two (2)
days. From May 1 to 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.
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 BMPs
intended to trap sediment on -site shall be constructed as a first step in grading. These
BMPs shall be functional before land distributing 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.
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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 sides of trenches.
(iii) Trench dewatering devices shall discharge into a sediment trap or sediment
pond.
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) onto the paved road. If
sediment is transported onto 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 sediment shall be removed or stabilized on sit. Disturbed soil areas
resulting from removal shall be permanently stabilized.
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L. 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 the 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 approve erosion and sediment control plan.
7.2.4 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.
7.2.5 Minimum requirement #3 — Source control of pollution
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 an approved
manual.
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.
7.2.6 Minimum requirement #4 — Runoff treatment BMPs
A. 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
18 Model Stormwater Management Ordinance
to ground water is prohibited. All treatment BMPs shall be selected, designed, and
maintained according to an approved manual.
B. Stormwater treatment BMPs shall not be built within a natural vegetated buffer,
except for necessary conveyance systems as approved by the City.
C. An adopted and implemented basin plan (Minimum Requirement #9) may be used to
develop runoff treatment requirements that are tailored to a specific basin.
7,23 Minimum requirement #5 — Streambank erosion control
A. 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:
B. Stormwater discharges to streams shall control steambank erosion by limiting the
peak rate of runoff from individual development sites to 50 percent of the existing
condition 2 -year, 24 -hour design storm while maintaining the existing condition peak
runoff rate for the 10 -year, 24 -hour 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 an approved manual.
C. Stormwater treatment BMPs shall not be built within natural vegetated buffer, except
for necessary conveyance systems as approved by the City.
D. An adopted and implemented basin plan (Minimum Requirement #9) may be used to
develop streambank erosion control requirements that are tailored to a specific basin.
7.2.8 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 Standard #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, Ch. 173 -201 WAC, or Ground
Water Quality Standards, Ch. 173 -200 WAC, as appropriate.
B. Discharges to wetlands shall maintain the hydroperiod and flows of existing sit
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,
an natural water storage and infiltration opportunities outside the wetland shall be
maximized.
19 Mode! Stormwater Management Ordinance
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 Ch. 90.48
RCW, Ch. 173 -201 WAC, and Ch. 173-200 WAC.
E. Stormwater treatment BMPs shall not be built within a natural vegetated buffer,
except for necessary conveyance systems as approved by the local government.
An adopted and implemented basin plan (Minimum Requirement #9) may be used to develop
requirements for wetlands that are tailored to a specific basin.
7,2,9 Minimum requirement #7 — Water quality sensitive areas
A. Where the City determines 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.
B. Stormwater treatment BMPS shall not be built within a natural vegetated buffer,
except for necessary conveyance systems as approved by the City.
C. 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.
7.2. 10 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
20 Model StormwaterManagement Ordinance
E. Spills and discharges of priority pollutants
7 2 11 Minimum requirement #9 — Basin planning
Adopted and implemented watershed -based basin plans may be used to modify any or all of
the Minimum Requirements, 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, retrofitting of BMPs for existing development and /or redevelopment 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
full implemented by local government. Basin plans shall be developed according to the
Manual.
7 2 12 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.
7 2 13 Minimum requirement #11 — Financial liability
Performance bonding or other appropriate financial instruments shall be required for all
projects to ensure compliance with these standards.
7.2.14 Exceptions
Exceptions to Minimum Requirements #1 through #11 may be granted prior to permit
approval and construction, as provided in Section 10 of this Chapter.
SECTION 8: ADMINISTRATION
8.1 Director
The Director shall administer this Ordinance under the supervision of the Mayor and the City
Administrator if so designated by the Mayor. The Director shall have the authority to develop and
implement administrative procedures, including written guidelines consistent with the YMC and
subject to review and approval by the City Council, to administer and enforce this Ordinance.
8.2 Review and approval
The Director may approve, conditionally approve or deny an application for activities regulated by
this Ordinance.
21 Model Stormwater Management Ordinance
8.3 Enforcement authori ty
The Director shall enforce this Ordinance under the supervision of the Mayor or City Administrator
if so designated.
8.4 Inspection
All activities regulated by this Ordinance, except those exempt in Section 5.2, shall be inspected by
the Director. The Director shall inspect projects at various states of the work requiring 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, landscaping, retaining walls and completion of project. When required by the Director, a
special inspection and/or testing shall be performed.
SECTION 9: ENFORCEMENT
9.1 General
Enforcement action shall be in accordance with this Ordinance whenever a person has violated any
provision of this Ordinance. The choice of enforcement action and the choice of penalties imposed
shall be based on the nature of the violation, the damage or risk to the public or to public resources,
and the existence or non - existence of bad faith of the person subject to the enforcement action.
• • • • V M
The Director shall have the authority to issue and serve a stop work order upon an owner as defined
in this chapter because of action being undertaken or threatening to be undertaken or continued in
violation of this Ordinance. If a portion of a project is in violation of this Ordinance, the Director
may issue a stop work order for the entire project.
A. Content of Order. The order shall contain:
(1) A description of the specific nature, extent, and time of violation and the damage or
potential damage; and
(2) A notice that the violation or the threatened violation cease and desist, and, in
appropriate cases, the specific corrective action to be taken within a given time. A
civil penalty under Section 9.3 below may be issued with the order.
B. Notice. A stop work order shall be imposed by a a notice in writing, either by certified mail
with return receipt requested, or by personal service, to the person incurring the same.
C. Effective Date. The stop work order issued under this Section shall become effective
immediately upon receipt by the person to whom the order is directed.
22 Model Stormwater Management Ordinance
D. Compliance. Failure to comply with the terms of a stop work order shall result in
enforcement action including, but not limited to, the issuance of a civil penalty.
9.3 Penalties and Procedures
An owner or person who fails to comply with the requirements of this Ordinance, who fails to
conform to the terms of an approval or order issued, who undertakes new development without first
obtaining City approval, or who fails to comply with a stop work order issued under these
regulations, and any person who aids or abets a violation, shall be deemed in violation of this chapter
and shall be subject to the remedies and penalties provided by this Chapter.
Unless otherwise provided or required by this chapter or other City ordinance, all enforcement
procedures and measures, including abatement and other remedies and penalties and appeals, shall
be as provided for nuisances or other violations in Chapter 9.48 YMC. For purposes of this section,
a violation of this chapter may be treated as a public nuisance and a stop work order may be issued,
served and enforced in the same manner as a notice of abatement under those provisions. The
Director is authorized and directed to adapt existing forms or adopt new forms to conform with
specific needs under this chapter. "Enforcement officer ", as used in those sections relating to
nuisances, means the Director provided for in this chapter. The term "hearing board ", unless
otherwise provided by ordinance, means the City Council. The maximum time for compliance
specified in Chapter 9.48 YMC may be extended by the Director for a reasonable time pursuant to
a written application by the owner or other affected person and the Director's written finding in the
record that good cause exists and that the extension and its duration will not result in significant
damage to health or environment, or defeat the purposes of this chapter.
In the case of conflict between this chapter and any other ordinance, this chapter shall control unless
there is a clearly expressed or implied contrary intent of the City's legislative body, or conflicting
statutory requirement.
SECTION 10: EXCEPTIONS
10.1 Authority of City Council
After a public hearing, the City Council may grant an exception from the requirements of this
Ordinance. In granting any exception, the Council may prescribe conditions that are deemed
necessary or desirable for the public interest.
10.2 Findinss of Fact
Exceptions to Minimum Requirement Nos. 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:
23 Model Stormwater Management Ordinance
A. 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;
B. 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;
C. 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
D. The exception is the least possible exception that could be granted to comply with the intent
of the Minimum Requirements.
10.3 Prior approval
Any exception shall be approved prior to permit approval and construction.
10A Duration of exception
Exceptions granted shall be valid for two (2) years, unless granted for a shorter period.
10.5 Right of appeal
All actions of the City shall be final and conclusive, unless within ten (10) days following the date of
the Council action, the original applicant or an adverse party gives written notice of appeal to the
Yelm Municipal Court for review of the action.
SECTION 11: SEVERABILITY
If any provision of this Ordinance or its application to any person, entity, or circumstance is held
invalid, the remainder of this Ordinance or the application of the provision to other persons, entities,
or circumstances shall not be affected.
24 Model Stormwater Management Ordinance
PASSED by the Yelm City Council this 4JQd, day of November, 1999.
olf, Mayor
Attest:
A
Agnds Bennick, Clerk/Treasurer
Passed and Approved: No-vember 23, 1899
Published: December 3, 1999
Effective Date: December 8, 1999
25 Model Stormwater Management Ordinance