HomeMy WebLinkAboutO-2694CITY OF MARYSVILLE
Marysville,Washington
ORDINANCE NO.2691
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AN ORDINANCE OF THE CITY OF MARYSVILLE,WASHINGTON,
AMENDING THE CITY'S DEVELOPMENT REGULATIONS RELATED TO
LOW IMPACT DEVELOPMENT AND AMENDING CHAPTERS 12.02A,
14.15, 14.16, 14.17, 19.06, 19.16, 19.24, 19.28, 20.12, AND 20.24, AND
ESTABLISHING A NEW CHAPTER 19.49, OF THE MARYSVILLE
MUNICIPAL CODE.
WHEREAS,the City Council ofthe City of Marysville finds that from time to time it is
necessary and appropriate to review and revise the City's regulations governing development,
such as those set forth in the City's Streets and Sidewalks Code (Title 12 MMC),Water and
Sewers Code (Title 14 MMC),Zoning Code (Title 19 MMC), and Subdivision Code (Title 20
MMC);and
WHEREAS,the City's Planning Commission is recommending that the City adopt
development regulations related to low impact development in order to encourage developers to
utilize more flexible land use development approaches,which can result in projects that
accomplish the goals ofthe Comprehensive Plan and that further the public interest ofthe City
and its citizens; and
WHEREAS,the amendments proposed for adoption in this ordinance are consistent with
the following required findings ofMMC 19.56.030:
(l)The amendments are consistent with the purposes ofthe Comprehensive Plan;
(2) The amendments are consistent with the purpose ofTitle 19 MMC;
(3) There have been significant changes in the circumstances to warrant a change;
(4) The benefit or cost to the public health, safety and welfare is sufficient to warrant the
action; and
WHEREAS,the Planning Commission discussed the above-referenced amendments during
public meetings February 13 and February 27, 2007; and
WHEREAS,after providing notice to the public as required by law, on February 27,2007,
the Marysville Planning Commission held a public hearing on proposed changes to the City's
development regulations;and
WHEREAS,at a public meeting on May 14,2007,the Marysville City Council reviewed
and considered the amendments to the City's development regulations proposed by the
Marysville Planning Commission;and
WHEREAS,the City ofMarysville has submitted the proposed development regulation
revisions to the Washington State Department of Community,Trade, and Economic
Development as required by RCW 36.70A.106;and
WHEREAS,the City has complied with the requirements ofthe State Environmental
Policy Act,Ch.43.2IC RCW, (SEPA) by adopting a determination ofnon-significance for the
adoption ofthe proposed revisions to the City's development regulations;
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,
!
NOW,THEREFORE,THE CITY COUNCIL OF THE CITY OF MARYSVILLE,
WASHINGTON DO ORDAIN AS FOLLOWS:
Section I:Chapter 12.02A MMC is hereby amended by amending Subsection (4)of
MMC 12.02A.030,Subsection (I)ofMMC 12.02A.090, and Subsection (3)of 12.02A.100 to
read as follows:
12.02A.030 General specifications.
(4)Existing drainage ditches, culverts, etc., shall be kept clean and protected from impacts
that may jeopardize their function at all times.Temporary diversion ofany drainage system will
not be permitted without the consent ofthe city engineer. Any drainage culvert tile, catch basins,
manholes,bioretention facility, pervious pavement,etc., disturbed by excavation or other
construction activities shall be replaced with new materials or repaired as directed by the city
engineer.
12.02A.090 Frontage improvements required.
(l)The term "frontage improvements"as used in this section shall refer to the
construction,reconstruction,or repair ofthe following facilities along the full abutting public
street frontage ofproperty being developed:
(a) Curbs, gutters, and sidewalks, except that curbs and gutters may be waived by the city
engineer when street drainage will be managed via a bioretention facility within the right-of-way.
Flow through curbs may be required by the City Engineer;
(b)Underground storm drainage facilities, except that surface facilities may be approved
by the city engineer pursuant to MMC 14.15.061;
c)Patching the street from its preexisting edge to the new curb line;
(d)Overlayment ofthe existing public street to its centerline.
All such frontage improvements shall be constructed to city specifications.
12.02A.I00 Minimum access requirements.
No development permits or short plats shall be issued or approved by the city for any lot,
parcel, or tract which does not comply with the following minimum access requirements:
(3) Each and every lot having access to a private road shall have responsibility for
maintenance of such private road and associated stormwater drainage facilities unless
specifically designated for maintenance by the City.
Section 2. Ch. 14.15 MMC is hereby amended by amending MMC 14.15.020 and
Subsections (2) and (7)ofMMC 14.15.050 and adding MMC 14.15.062 to read as follows:
_.
14.15.020 Definitions.
For the purpose of this chapter, certain terms, phrases, words and their derivatives shall be
construed as specified in this section. Words used in the singular include the plural, and the
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plural the singular. The words "shall,""will"and "must"are mandatory;the words "should"and
"may"are permissive. When any definition in this chapter conflicts with definitions in the
manual or any other ordinance of the city, that which provides more environmental protection
shall apply unless specifically provided otherwise in this chapter.
(I)"Adjustment"means a project proposal that has received approval as providing
substantially equivalent environmental protection while maintaining the objectives of safety,
function, and facility maintenance based upon sound engineering.
(2)"Applicant"means any person who has applied for a development permit or approval.
(3)"Basin plan" means a plan that assesses,evaluates,and proposes solutions to existing and
potential future impacts to the beneficial uses of, and the physical,chemical, and biological
properties of waters of the state within a basin.!A plan should include but not be limited to
recommendations for:
(a) Storm water requirements for new development and redevelopment;
(b) Capital improvement projects;
(c) Land use management through identification and protection of critical areas,
comprehensive land use and transportation plans,zoning regulations,site development standards,
and conservation areas;
(d) Source control activities including public education and involvement,and business
programs;
(e) Other targeted storm water programs and activities,such as maintenance,inspections,
and enforcement;
(f)Monitoring;and
(g) An implementation schedule and funding strategy.
(4)"Best management practices (BMPs)"refers to the schedules ofactivities,prohibitions of
practices,maintenance procedures,and structural and/or managerial practices,that when used
singly or in combination,prevent or reduce pollution ofwater and have been approved by the
engineer. BMPs include, but are not limited to,infiltration,retention and/or detention, dispersion,
amended soils,biofiltration facilities,bioretention facilities, open ditches with check dams, filter
fabric strips,oil/water separators,wet ponds,constructed wetlands,erosion and sedimentation
control, and other treatment/abatement facilities.
(5)"Biofiltration facility"means the simultaneous processes of filtration, absorption, and
biological uptake ofpollutants in storm water to take place when runoff flows over and through
vegetated treatment facilities.
(6)"Bioretention"means a terrestrial-based (upland as opposed to wetland),water quality and
water quantity control practice using the chemical,biological,and physical properties of plants,
microbes, and soils for removal of pollutants from storm water runoff. Some of the processes
that may take place in a bioretention facility include:sedimentation,absorption,filtration,
volatilization,ion exchange,decomposition,phytoremediation,bioremediation,and storage
capacity.Bioretention may be designed to help mimic predevelopment hydrology.
(7)"City planner"also means community development director.
(8)"Clearing"means the destruction and removal of vegetation by manual,mechanical or
chemical methods.
(9)"Comprehensive drainage plan"means a detailed analysis adopted by the city which
compares the capabilities and needs for runoff accommodation due to various combinations of
development,land use, structural and nonstructural management alternatives.The plan
recommends the form, location, and extent of quantity and quality control measures which would
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satisfy legal constraints, water quality standards and community standards and identifies the
institutional and funding requirements for plan implementation.
(10)"Computations"means calculations, including coefficients and other pertinent data made
to determine the drainage plan with flow ofwater given in cubic feet per second (cfs).
(II)"Construction storm water pollution prevention plan" or "construction SWPPP" means a
plan that includes a narrative, drawings, and details for describing construction practices,
stabilization teclmiques, and structural BMPs that are to be implemented to prevent erosion and
sedimentation, and control other pollutants at a construction site.
(12) "Conveyance system" means the drainage facilities, both natural and manmade, which
collect, contain, and provide for the flow of surface and storm water from the highest points on
the land down to a receiving water. The natural elements of the conveyance system include
swales and small drainage courses, streams, rivers, lakes, and wetlands. The human-made
elements of the conveyance system include gutters, ditches, pipes, channels, and most
retention/detention facilities.
(13)"Current conditions" means the state, status, or conditions (land use, impervious surfaces,
topography, soils, and surface water flows) present of the subject property at the time the
analysis is conducted.
(14) "Cut and fill" means the process ofearth moving by excavating part of an area and using
the excavated material for adjacent embankments or fill areas.
(15)"Department"means the public works or community development department ofthe city
ofMarysville, as appropriate for capital or private development projects.
(16) "Design storm" means a rainfall (or other precipitation) event or pattern of events for use
in analyzing and designing drainage facilities, specifying both the return period in years and the
duration in hours.
(17)"Detention"means the release of storm water runoff from the site at a slower rate than it
is collected by the storm water drainage system, the difference being held in temporary storage.
(18)"Detention facility" means an above or below ground facility, such as a pond or tank, that
temporarily stores storm water runoff and subsequently releases it at a slower rate than it is
collected by the drainage facility system. There is little or no infiltration ofstored storm water.
(19) "Developed conditions"means the state, status, or condition ofthe subject property at the
time the proposed project has been completed, which may include existing buildings, impervious
areas, and topography as is.
(20)"Developer"means the individual(s) or corporation(s) or governmental agency(ies)
applying for the permits or approvals described in MMC 14.15.030.
(21)"Development"means any artificial change to property, including but not limited to
building or other structures, mining, dredging, filling, all land-disturbing activities, clearing,
grading, landscaping, paving, excavation, or drilling operations, any activity that requires a
permit or approval, including but not limited to a building permit, grading permit, shoreline
substantial development permit, conditional use permit, unclassified use permit, zoning variance
or reclassification, planned unit development, subdivision, short subdivision, master plan
development, building site plan, or right-of-way use permit.
(22)"Developmental coverage"means all developed areas within the subject property
including but not limited to rooftops, driveways, carports, accessory buildings, parking areas,
and any other impervious surfaces. During construction,"development coverage" includes the
above in addition to the full extent of any alteration of previously occurring soils, slope, or
vegetation due to grading, temporary storage, access areas, or other short-term causes.
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(23)"Director of public works"or "director"means the director of the public works
department or hislher designee.
(24)"Drainage area"means the watershed (acreage)contributing surface water runoff to and
including the subject property.
(25)"Drainage site"means a geographical area that serves a common or combined use
including but not limited to shopping malls and strips,condominiums,apartment complexes,
office parks, and housing tracts. A site may include one or more parcels and/or include one or
more buildings. See also "Development."
(26)"Drainage system"means the system of collecting,conveying,and storing surface and
storm water runoff.Drainage facilities shall include but not be limited to all surface and storm
water runoff conveyance and containment facilities including streams,pipelines,channels,
ditches, swamps, lakes, wetlands, closed depressions,infiltration facilities,retention/detention
facilities,erosion/sedimentation control facilities, and other drainage structures and
appurtenances,both natural and manmade.
(27)"Drainage treatment/abatement facilities" means any facilities installed or constructed in
conjunction with a drainage plan for the purpose of treating urban runoff to improve water
quality,excluding retention or detention facilities.
(28)"Effective impervious area" means those impervious surfaces that are connected via sheet
flow or discrete conveyance to a drainage system.
(29)"Engineer"means the city engineer or development services manager,as designated for
enforcement ofcapital or private development activities,of Marysville.
(30)"Environmentally sensitive areas" means areas defined as such by the Marysville
sensitive areas ordinance.
(31)"Erosion"means the wearing away of the land surface by running water, wind, ice or
other geological agents,including such processes as gravitational creep, and the detachment and
movement ofsoil or rock fragments by water, wind, ice or gravity.
(32)"Erosion and sediment control"means any temporary or permanent measures taken to
reduce erosion,control siltation and sedimentation,and ensure that sediment-laden water does
not leave the site.
(33)"Excavation"means the mechanical removal ofearth material.
(34)"Exception"means relieffrom specific mandates ofa minimum requirement.
(35)"Fill"means a deposit ofearth material placed by artificial means.
(36)"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:
(a)Road and trail construction;
(b)Harvesting,final and intermediate;
(c)Pre-commercial thinning;
(d)Reforestation;
(e)Fertilization;
(f)Prevention and suppression ofdiseases and insects;
(g) Salvage oftrees; and
(h) Brush control.
(37)"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 ofconstruction such as paving or the laying of a conduit.
(38)"Existing grade"means the grade prior to grading.
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(39) "Rough grade" means the stage at which the grade approximately conforms to the
approved plan.
(40) "Finish grade" means the final grade ofthe site, which conforms to the approved plan.
(41)"Grading"or "grading activity" means any excavating, filling, or grading or combination
thereof.
(42) "Ground water" means water in a saturated zone or stratum beneath the surface ofland or
a surface water body.
(43) "Illicit discharge" means all non-storm water discharges to storm water 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 gray water systems.
(44) "Impervious areas" means that hard surface area which either prevents or retards the entry
of water into the soil mantle and/or causes water to run offthe surface in greater quantities or at
an increased rate of flow from that 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 oil, macadam, or other surfaces which similarly impede the natural infiltration of
surface and storm water runoff. Open, uncovered retention/detention facilities shall not be
considered as impervious surfaces for the purposes ofthis chapter.
(45)"Interflow"means that portion of rainfall that infiltrates into the soil and moves laterally
through the upper soil horizons until intercepted by a stream charmel or until it returns to the
surface for example, in a roadside ditch, wetland, spring or seep.
(46) "Land clearing" or "clearing"means the destruction or removal of vegetation from a site
by physical, mechanical, chemical or other means. This does not mean mowing, landscape
maintenance or pruning consistent with accepted horticultural and arboricultural practices, which
does not impair the health or survival ofthe trees and associated vegetation.
(47)"Land-disturbing activities" means any activity that disturbs or alters land surface
including clearing and grading.
(48)"LID Technical Guidance Manual" means the January 2005 Low Impact Development
Technical Guidance Manual for Puget Sound, published by the Puget Sound Action Team and
the Washington State University Pierce County Extension.
(49) "Lowest floor" means the lowest enclosed area (including basement)of a structure.An
area used solely for parking ofvehicles, building access, or storage is not considered a building's
lowest floor; provided, that the enclosed area meets all ofthe structural requirements ofthe flood
hazard standards.
(50)"Manual"refers to the Washington Department of Ecology's "Storm Water Management
Manual for Western Washington," as amended.
(51) "Native vegetation" means vegetation comprised of plant species, other than noxious
weeds, that are indigenous to the coastal region of the Pacific Northwest and which reasonably
couId have been expected to naturally occur on the site. Examples include trees such as Douglas
fir, western hemlock, western red cedar, alder,big-leaf maple, and vine maple; shrubs such as
willow, elderberry, salmonberry, and salal; and herbaceous plants such as sword fern, foam
flower, and fireweed.
(52) "Natural location"of drainage systems refers to the location of those charmels, swales,
and other natural 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.
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(53) "New development" means the following activities: land-disturbing activities; structural
development, including construction, installation, or expansion of building or other structures;
installation ofimpervious surfaces, and subdivisions or short plats.
(54) "On-site storm water management BMPs" means site development techniques that serve
to infiltrate, disperse, and retain storm water runoffon-site.
(55)"Parcel"means a tract or plot of land ofany size, which mayor may not be subdivided or
improved.
(56)"Permanent erosion and sediment control" means the continuous on-site and off-site
control measures that are needed to prevent accelerated erosion, sedimentation or related
pollution from occurring after completion ofthe grading activity or the construction project.
(57)"Permanent storm water control (PSC) plan" means a plan which includes permanent
BMPs for the control of pollution from storm water runoff after construction and/or land-
disturbing activity has been completed.
(58)"Person"means any individual, partnership, corporation, association, organization,
cooperative, public or municipal corporation, agency of the state, or local government unit,
however designated.
(59) "Planned residential developments" refers to residential developments which are planned
and/or developed in several stages but submitted together for approvals, and which typically
consist of clusters ofstructures interspersed with areas of common open spaces (refer to Chapter
19.48MMC).
(60)"Pollutant"shall mean any substance which, when added to water, would contaminate or
alter the chemical, physical, or biological properties of any waters ofthe city's drainage system
or of the state. This includes a 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 city's drainage system or ofthe state as will or is likely to create a nuisance.It also
includes any substance which renders such waters harmful, detrimental, or injurious to the public
health, safety, or welfare, or to domestic, commercial, industrial, agricultural, recreational, or
other legitimate beneficial use, or to livestock, wild animals, birds, fish, or other aquatic life.
(61)"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 and 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, recreation or other legitimate beneficial uses, or to
livestock, wild animals, birds, fish, or other aquatic life.
(62)"Pollution-generating impervious surface (PGIS)" means those impervious surfaces
considered to be a significant source of pollutants in storm water runoff. Such surfaces include
those which are subject to: vehicular use; industrial activities; or storage of erodible or leachable
materials, wastes, or chemicals, and which receive direct rainfall or the run-on or blow-in of
rainfall. Erodible or leachable materials, wastes, or chemicals are those substances which, when
exposed to rainfall,measurably alter the physical, or chemical characteristics of the rainfall
runoff. Examples include erodible soils that are stockpiled, uncovered process wastes, manure,
fertilizers, oily substances, ashes, kiln dust, and garbage dumpster leakage. Metals roofs are also
considered to be PGIS unless they are coated with an inert, nonleachable material (e.g., baked-on
enamel coating).
A surface, whether paved or not, shall be considered subject to vehicular use if it is regularly
used by motor vehicles. The following are considered regularly used surfaces: roads, unvegetated
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road shoulders,bike lanes within the traveled lane of a roadway,driveways,parking lots,
unfenced fire lanes,vehicular equipment storage yards, and airport runways.
The following are not considered regularly used surfaces:paved bicycle pathways separated
from and not subject to drainage from roads for motor vehicles,fenced fire lanes, and
infrequently used maintenance access roads.
(63)"Pollution-generating pervious surface (POPS)"means any nonimpervious surface
subject to use ofpesticides,fertilizers,or loss ofsoil.
(64)"Private drainage system"means drainage systems located on private property and
designed to discharge directly as through pipes,channels,etc., or indirectly as sheet flow,
subsurface flow, etc., into the city's drainage system.
(65)"Project site" means that portion ofa property,properties,or right-of-way subject to land-
disturbing activities,new impervious surfaces,or replaced impervious surfaces.
(66)"Public drainage system"means that portion ofthe drainage system of the city located on
public right-of-way,easements or other property owned by the city, and those portions ofprivate
drainage systems operated and maintained by the city.
(67)"Receiving waters"means bodies ofwater or surface water systems receiving water from
upstream manmade (or natural)systems. For the purpose of this chapter,receiving waters are
Ebey Slough and the Snohomish River.
(68)"Redevelopment"means, on an already developed site, the creation and/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.
(69)"Regional"means an action that involves more than one discrete parcel.
(70)"Regional detention facility"means a storm water quantity control structure designed to
correct existing surface water runoff problems for all or a portion of a basin or sub-basin. This
term is also used when a detention facility is used to detain storm water runofffrom a number of
different businesses,developments or areas within a catchment.
(71)"Replaced impervious surface"means the removal and replacement of any exterior
impervious surfaces or foundation of a structure.Other impervious surfaces are considered
replaced if first removed down to bare soil or base course.
(72)"Retention/detention facility (RID)"means a type of drainage system 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 storm water runoff for
short period oftime and then release it to the surface and storm water management system.
(73)"Sediment"means solid particulate matter, both mineral and organic,that has been or is
being transported by water, air, gravity, or ice from its original site oforigin.
(74)"Sedimentation"means the process by which sediment has been transported offthe site of
the grading activity and settled onto land or the bed of a creek, stream, river,wetland,pond, or
other water body.
(75)"Site"means the area defined by the legal boundaries of a parcel or parcels of land
subject to new development or redevelopment.For road projects,the length of the project site
and the right-of-way boundaries define the site.
(76)"Site plan"means a plan which indicates the character of the existing site,topography,
natural drainage features on or adjacent to the site, the location and dimensions ofall impervious
surfaces, flow arrows indicating the direction ofstorm water flows on-site,and any off-site flows
entering the site, the proposed method ofutilizing the existing drainage system.
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(77) "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.
(78)"Soil"means the unconsolidated mineral and organic material on the immediate surface
ofthe earth that serves as a natural medium for the growth ofland plants.
(79) "Source control BMP" means a structure or operation that is intended to prevent
pollutants from coming into contact with storm water through physical separation of areas or
careful management of activities that are sources ofpollutants. A few examples of source control
BMPs are erosion control practices, maintenance of storm water facilities, constructing roofs
over storage and working areas, and directing wash water and similar discharges to the sanitary
sewer or a dead end sump.
(80)"Storm drainage plan" means a plan approved by the city of Marysville which includes
either a small parcel or large parcel erosion and sediment control plan and/or a water quality
control plan.
(81) "Storm water" means that portion of precipitation that does not naturally percolate into
the ground or evaporate, but flows via overland flow, interflow, pipes, or other features of a
storm water drainage system into a defined surface waterbody or a constructed infiltration
facility.
(82) "Storm Water Management Manual for Western Washington" means the manual
prepared by the Department of Ecology that contains BMPs to prevent or reduce pollution.
(83) "Storm water site plan" means the comprehensive report containing all of the technical
information and analysis necessary to evaluate a proposed new development or redevelopment
project for compliance with storm water requirements. Contents ofthe storm water site plan will
vary with the type and size of the project, and individual site characteristics.It includes a
construction storm water pollution prevention plan (construction SWPPP) and a permanent storm
water control plan (PSC plan).
(84) "Subject property" means the tract of land which is the subject of the permit and/or
approval action.
(85) "Surface water" means the naturally occurring water that flows over or is stored on the
earth's surface.
(86)"Temporary erosion control" means the on-site and off-site control measures that are
needed during construction activities to prevent accelerated erosion, sedimentation or related
pollution from occurring, but may not be needed when the project is completed or when ground
conditions have been stabilized by permanent erosion control measures.
(87)"Threshold discharge area" means an on-site area draining to a single natural discharge
location or multiple natural discharge locations that combine within one-quarter mile
downstream (as determined by the shortest flowpath).
(88) "Total maximum daily load (TMDL)" means a calculation of the maximum amount of a
pollutant that a waterbody can receive and still meet water quality standards, and an allocation of
that amount to the pollutant's sources.
(89) "Undeveloped conditions" means the state, status, or condition of the subject property
prior to any development of the property that has occurred, which may include trees, pastures,
meadows, or native features.
(90)"Uncontaminated"means water that has not come into contact with illicit discharges.
(91)"Waterbody"means surface waters including rivers, streams, lakes, marine waters,
estuaries and wetlands.
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(92)"Water quality control plan (WQCP)" means a plan which includes permanent BMPs for
the control ofpollution from storm water runoff after construction and/or land-disturbing activity
has been completed.
(93)"Water quality design flow rate" means:
(a) Preceding detention facilities or when detention facilities are not required: that rate at or
below which 91 percent of the runoff volume, as estimated by an approved continuous runoff
model, will be treated.
(b)Downstream of detention facilities: the full two-year release rate from the detention
facility.
(94)"Water quality design storm" means the 24-hour rainfall amount with a six-month return
frequency.It is commonly referred to as the six-month, 24-hour design storm.
(95)"Water quality design storm volume" means the volume of runoff predicted from a 24-
hour storm with a six-month return frequency.
(96)"Watershed"means a geographic region within which water drains into a particular river,
stream, or body ofwater as identified and numbered by the State ofWashington Water Resource
Inventory Areas (WRIAs) as defined in Chapter 173-500 WAC or succeeding regulation.
(97)"Wetland"or "wetlands"means areas that are inundated or saturated by surface water 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."Wetlands"
do not include those artificial wetlands intentionally created from nonwetland sites, including,
but not limited to, irrigation and drainage ditches, grass-lined swales, canals, detention facilities,
wastewater treatment facilities, farm ponds, and landscape amenities. However,"wetlands"
include those artificial wetlands intentionally created to mitigate conversion of wetlands. See the
Federal Manual for Identifying and Delineating Jurisdictional Wetlands (January, 1987) for more
information.
14.15.50 Minimum requirements.
(2) Minimum Requirement No.2:Construction Storm Water Pollution Prevention (SWPP).
All new development and redevelopment shall comply with construction SWPP elements
numbers. 1through 12 below.
(a) Projects in which the new, replaced, or new plus replaced impervious surfaces total
2,000 square feet or more or disturb 7,000 square feet or more of land must prepare a
construction SWPP plan (SWPPP) as part of the storm water site plan. Each ofthe 12 elements
must be considered and included in the construction SWPPP unless the director decides that site
conditions render the element unnecessary and the exemption from that element is clearly
justified in the narrative ofthe SWPPP.
(b) Projects that add or replace less than 2,000 square feet ofimpervious surface or
disturb less than 7,000 square feet ofland are not required to prepare a construction SWPPP but
must consider all ofthe 12 elements ofconstruction stormwater pollution prevention and develop
controls for all elements that pertain to the project site.
(c) Element 1:Mark Clearing Limits.
(i) Prior to beginning land disturbing activities, including clearing and grading, all
clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the
construction area should be clearly marked, both in the field and on the plans, to prevent damage
and off-site impacts.
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(ii) Plastic, metal, or stake wire fence may be used to mark the clearing limits.
(d)Element 2: Establish Construction Access.
(i) Access Limited. Construction vehicle access and exit shall be limited to one route if
possible.
(ii) Tracking Sediment. Access points shall be stabilized with quarry spall or crushed
rock to minimize the tracking ofsediment onto public roads.
(iii) Wheel Wash. Wheel wash or tire baths should be located on-site,ifapplicable.
(iv) Clean Public Roads. Public roads shall be cleaned thoroughly at the end of each
day. Sediment shall be removed from roads by shoveling or pickup sweeping and shall be
transported to a controlled sediment disposal area. Street washing will be allowed only after
sediment is removed in this manner.
(v) Street Wash Water. Street wash wastewater shall be controlled by pumping back
on-site, or otherwise be prevented from discharging into systems tributary to state surface waters.
(e)Element 3: Control Flow Rates.
(i) General. Properties and waterways downstream from development sites shall be
protected from erosion due to increases in the volume, velocity, and peak flow rate of storm
water runofffrom the project site.
(ii)Downstream Analysis. Downstream analysis is necessary if changes in flows could
impair or alter conveyance systems, stream banks, bed sediment or aquatic habitat.
(iii) BMPs Functional. Storm water retention/detention facilities shall be constructed as
one of the first steps in grading. Detention facilities shall be functional prior to construction of
site improvements (e.g., impervious surfaces).
(iv) Additional Flow Standards. The director may require pond designs that provide
additional or different storm water flow control if necessary to address local conditions or to
protect properties and waterways downstream from erosion due to increases in the volume,
velocity, and peak flow rate ofstorm water runoff from the project site.
(v)Permanent Infiltration Ponds.If permanent infiltration ponds are used for flow
control during construction, these facilities should be protected from siltation during the
construction phase.
(f)Element 4: Install Sediment Controls.
(i) Native Vegetation and Soils. The dufflayer,native top soil, and native vegetation
shall be retained in an undisturbed state to the maximum extent practicable.Duff and native top
soil should be retained and reused on site to the maximum extent practicable. Where retention
and reuse is not feasible or when existing site soils are disturbed, areas not intended for
impervious surfaces, pervious paving, or within the dripline ofpreserved trees shall be amended
with four inches ofwell-composted organic matter mixed into the top eight inches ofsoil or
should have an organic content ofbetween 8 and 13percent dry weight and a pH suitable for
proposed plantings.Deeper soil amendment will provide improved growing medium and
increased water holding capacity.
(ii) Sediment Removal BMP. Prior to leaving a construction site, or prior to discharge
to an infiltration facility, storm water runoff from disturbed areas shall pass through a sediment
pond or other appropriate sediment removal BMP.Runoff from fully stabilized areas may be
discharged without a sediment removal BMP, but must meet the flow control performance
standard of element no. 3. Full stabilization means concrete or asphalt paving; quarry spalls used
as ditch lining; or the use of rolled erosion products, a bonded fiber matrix product, or vegetative
cover in a manner that will fully prevent soil erosion. The director shall inspect and approve
areas stabilized by means other than pavement or quarry spalls.
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(iii) BMPs Functional. Sediment ponds, vegetated buffer strips, sediment barriers or
filters, dikes, and other BMPs intended to trap sediment on-site shall be constructed as one ofthe
first steps in grading. These BMPs shall be functional before other land disturbing activities take
place.
(iv) Seeding. Earthen structures such as dams, dikes, and diversions shall be seeded
and mulched according to the timing indicated in element no. 5.
(g) Element 5: Stabilize Soils.
(i) General. All exposed and unworked soils shall be stabilized by application of
effective BMPs that protect the soil from the erosive forces of raindrop impact and flowing
water, and wind erosion.
(ii) Applicable Practices. Applicable practices include, but are not limited to,
temporary and permanent seeding, sodding, mulching, plastic covering, soil application of
polyacrylamide (PAM), early application ofgravel base on areas to be paved, and dust control.
(iii) Soil Stabilization. Soil stabilization measures selected should be appropriate for
the time of year, site conditions, estimated duration of use, and potential water quality impacts
that stabilization agents may have on downstream waters or ground water.
(iv) Soil Stockpiles. Soil stockpiles must be stabilized and protected with sediment
trapping measures.
(v) Linear Facilities. Work on linear construction sites and activities, including right-
of-way and easement clearing, roadway development, pipelines, and trenching for utilities, shall
not exceed the capability ofthe individual contractor for his portion of the project to install the
bedding materials, roadbeds, structures, pipelines, and/or utilities, and to restabilize the disturbed
soils, meeting the timing conditions listed above in subsection (2)(g)(ii)ofthis section.
(h) Element 6: Protect Slopes.
(i) Cut and Fill Slopes. Cut and fill slopes shall be designed and constructed in a
manner that will minimize erosion.
(ii) Soil Types. Consider soil type and its potential for erosion.
(iii)Runoff Velocities. Reduce slope runoff velocities by reducing the continuous
length of slope with terracing and diversions, reduce slope steepness, and roughen slope surface.
(iv) Diverted Flows. Divert upslope drainage and run-on waters from off-site with
interceptors at top of slope. Off-site storm water should be handled separately from storm water
generated on the site. Diversion of off-site storm water around the site may be a viable option.
Diverted flows shall be redirected to the natural drainage location at or before the property
boundary.
(v) Collected Flows. Contain downslope collected flows in pipes, slope drains, or
protected channels.
(vi) Ground Water. Provide drainage to remove ground water intersecting the slope
surface ofexposed soil areas.
(vii) Excavation. Excavated material shall be placed on the uphill side of trenches,
consistent with safety and space considerations.
(viii) Check Dams. Check dams shall be placed at regular intervals within trenches that
are cut down a slope.
(ix) Stabilize Soils. Stabilize soils on slopes, as specified in element no. 5.
(i) Element 7: Protect Drain Inlets.
(i) General. All storm drain inlets made operable during construction shall be protected
so that storm water runoff shall not enter the conveyance system without first being filtered or
treated to remove sediment.
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(ii) Roads. All approach roads shall be kept clean, and all sediment and street wash
water shall not be allowed to enter storm drains without prior and adequate treatment unless
treatment is provided before the storm drain discharges to waters ofthe state.
OJ Element 8: Stabilize Channels and Outlets.
(i) General. All temporary on-site conveyance channels shall be designed, constructed
and stabilized to prevent erosion from the expected velocity of flow from a two-year, 24-hour
frequency storm for the developed condition.
(ii) Stabilization. Stabilization, including armoring material, adequate to prevent
erosion of outlets, adjacent stream banks, slopes and downstream reaches shall be provided at the
outlets ofall conveyance systems.
(k) Element 9: Control Pollutants.
(i) General. All pollutants, including waste materials and demolition debris, that occur
on-site during construction shall be handled and disposed of in a manner that does not cause
contamination ofstorm water.
(ii) Vandalism. Cover, containment, and protection from vandalism shall be provided
for all chemicals, liquid products, petroleum products, and noninert wastes present on the site.
(iii) Equipment Maintenance. Maintenance and repair ofheavy equipment and vehicles
involving oil changes, hydraulic system drain down, solvent and degreasing cleaning operations,
fuel tank drain down and removal, and other activities which may result in discharge or spillage
of pollutants to the ground or into storm water runoff must be conducted using spill prevention
measures, such as drip pans. Contaminated surfaces shall be cleaned immediately following any
discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic
placed beneath and,ifraining, over the vehicle.
(iv) Wheel Wash. Wheel wash, or tire bath wastewater, shall be discharged to a
separate on-site treatment system. It may be discharged to the sanitary sewer system only if
expressly allowed by the local sewer district authority.
(v) Agricultural Chemicals. Application of agricultural chemicals, including fertilizers
and pesticides, shall be conducted in a manner and at application rates that will not result in loss
of chemical to storm water runoff.Manufacturers'recommendations shall be followed for
application rates and procedures.
(vi) pH Management. Management of pH-modifying sources shall prevent
contamination of runoff and storm water collected on the site. These sources include, but are not
limited to, bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters,
waste streams generated from concrete grinding and sawing, exposed aggregate processes, and
concrete pumping and mixer washout waters.
(I)Element 10:Control Dewatering.
(i) General. All foundation, vault, and trench dewatering water, which have similar
characteristics to storm water runoff at the site, shall be discharged into a controlled conveyance
system, prior to discharge to a sediment trap or sediment pond. Channels must be stabilized, as
specified in element no. 8.
(ii) Clean Water. Clean, nonturbid dewatering water, such as well-point ground water,
can be discharged to systems tributary to state surface waters, as specified in element no. 8,
provided the dewatering flow does not cause erosion or flooding of the receiving waters. These
clean waters should not be routed through sediment ponds with storm water.
(iii) Contaminated Water. Highly turbid or otherwise contaminated dewatering water,
such as from construction equipment operation, clamshell digging, concrete tremie pour, or work
inside a cofferdam, shall be handled separately from storm water at the site.
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(iv) Other Disposal Options. Depending on site constraints, dewatering may include:
infiltration; transport off-site in vehicle, such as a vacuum flush truck, for legal disposal in a
manner that does not pollute state waters; on-site treatment using chemical treatment or other
suitable treatment technologies; or sanitary sewer discharge with (local sewer district approval)
approval ifthere is no other option.
(m) Element II:Maintain BMPs.
(i)General. 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 BMPs.
(ii) Inspection. Sediment control BMPs shall be inspected weekly or after a runoff-
producing storm event during the dry season and daily during the wet season.
(iii) Remove 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-site. Disturbed soil areas
resulting from removal ofBMPs or vegetation shall be permanently stabilized.
(n) Element 12: Manage the Project.
(i) Phasing of Construction. Development projects shall be phased where feasible in
order to prevent, to the maximum extent practicable, the transport of sediment from the project
site during construction. Revegetation of exposed areas and maintenance of that vegetation shall
be an integral part of the activities for any phase. Clearing and grading activities for
developments shall be permitted only if conducted pursuant to an approved site development
plan (e.g., subdivision approval) that establishes permitted areas ofclearing, grading, cutting, and
filling. When establishing these permitted clearing and grading areas, consideration should be
given to minimizing removal ofexisting trees and minimizing disturbance/compaction of native
soils except as needed for building purposes. These permitted clearing and grading areas and any
other areas required to preserve critical or sensitive areas, buffers, native growth protection
easements, or tree retention areas as may be required by the director, shall be delineated on the
site plans and the development site.
(ii) Coordination with Other Contractors. The primary project applicant shall evaluate,
with input from utilities and other contractors, the storm water management requirements for the
entire project, including the utilities, when preparing the construction SWPPP.
(iii) Inspection. All BMPs shall be inspected, maintained, and repaired as needed to
assure continued performance oftheir intended function.
(A) Certified Professional. A certified professional in erosion and sediment control
shall be identified in the construction SWPPP and shall be on-site or on-call at all times.
Certification may be through the Washington State Department of Transportation/Associated
General Contractors (WSDOT/AGC) Construction Site Erosion and Sediment Control
Certification Program or any equivalent local or national certification and/or training program.
(B) Sampling. Sampling and analysis of the storm water discharges from a
construction site may be necessary on a case-by-case basis to ensure compliance with standards.
Monitoring and reporting requirements may be established by the director when necessary.
(C)Modify SWPPP. Whenever inspection and/or monitoring reveals that the
BMPs identified in the construction SWPPP are inadequate, due to the actual discharge of or
potential to discharge a significant amount of any pollutant, the SWPPP shall be modified, as
appropriate, in a timely manner.
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(iv)Construction SWPPP. The construction SWPPP shall be retained on-site or within
reasonable access to the site. The construction SWPPP shall be modified whenever there is a
significant change in the design,construction,operation,or maintenance of any BMP.
(7)Minimum Requirement No.7:Flow Control.
(a)Applicability.
(i) Flow Control.Projects must provide flow control to reduce the impacts of storm
water runoff from impervious-surfaces and land cover conversions.The requirement below
applies to projects that discharge storm water directly, or indirectly,through a conveyance
system, into fresh water, except for discharges into a wetland. (See minimum requirement no. 8
for flow control requirements applicable to discharges to wetlands.)
(ii)Exempt Areas. The director may petition the Department of Ecology to exempt
projects in certain areas provided those areas also meet the following criteria:
(A) The area must be drained by a conveyance system that is comprised entirely of
manmade conveyance elements (e.g., pipes, ditches, outfall protection,etc.) and extends to the
ordinary high water line ofthe receiving water; and
(B) Any erodible elements of the manmade conveyance system for the area must
be adequately stabilized to prevent erosion;and
.(C) Surface water from the area must not be diverted from or increased to an
existing wetland, stream, or near-shore habitat sufficient to cause a significant adverse impact.
(b)Thresholds.The following require construction of flow control facilities and/or land
use management BMPs that will achieve the standard requirement for western Washington (see
subsection (7)(c)ofthis section):
Table 14 15 050(7)(b).
Flow Control Requirements by Threshold Discharge Area
Flow On-Site
Control Storm Water Management
Facilities BMPs
<3/4 acres conversion to lawn/landscape,or <2.5 ...jacres to pasture
> 3/4 acres conversion to lawn/landscape,or>2.5 ...j ...jacres to pasture
<10,000 square feet ofeffective impervious area ...j
> 10,000 square feet ofeffective impervious area ...j ...j
> 0.1 cubic feet per second increase in the 100-year ...j ...jflood frequency
(1)Projects III which the total of effectIve impervious surfaces is 10,000 square feet or
more in a threshold discharge area; or
(ii)Projects that convert three-quarters acres or more of native vegetation to lawn or
landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold discharge
area, and from which there is a surface discharge in a natural or manmade conveyance system
from the site; or
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(iii) Projects that through a combination of effective impervious surfaces and
converted pervious surfaces, cause a 0.1 cubic feet per second increase in the 100-year flow
frequency from a threshold discharge area as estimated using the Western Washington
Hydrology Model or other model authorized by the director.
(iv)That portion of any development project in which the above thresholds are not
exceeded in a threshold discharge area shall apply on-site storm water management BMPs in
accordance with minimum requirement no. 5.
(c) Standard Requirement.
(i) Peak Flows. Storm water discharges shall match developed discharge durations to
predeveloped durations for the range ofpredeveloped discharge rates from 50 percent ofthe two-
year peak flow up to the full 50-year peak flow.
(ii)Predeveloped Condition. The predeveloped condition to be matched shall be a
forested land cover unless reasonable,historic information is provided that indicates the site was
prairie prior to settlement (modeled as "pasture"in the Western Washington Hydrology Model).
This standard requirement is waived for sites that will reliably infiltrate all the runoff from
impervious surfaces and converted pervious surfaces.
(d) Flow Control Facility Selection, Design, and Maintenance. Flow control facilities shall
be selected, designed, and maintained in accordance with the manual.
(e) The base ofa permanent infiltration systems shall be a minimum ofthree feet above
the seasonal high ground-Water mark,except ifbioretention swales or cells are used for
infiltration, a minimum ofone-foot clearance between the bottom ofthe bioretention soil (or any
underlying gravel layer) and the seasonal high groundwater elevation or other permeable layer is
allowed for bioretention facilities meeting the following tributary area limitations:
(i) 5,000 square feet ofpollution-generating impervious surface; or
(ii) 10,000 square feet ofimpervious area; or
(iii)%acres oflawn and landscape.
14.15.062 Low impact development (LID)-alternative drainage standards.
Low impact BMPs are an alternative to conventional stormwater management systems that rely
on detention ponds and closed conveyance. Instead, low impact development is intended to
manage runoff close to the source of generation and to mimic the pre-developed hydrologic
condition ofa site. This is accomplished first through minimizing the impervious surface
coverage and second by managing runoffthrough dispersion, infiltration,evapo-transpiration,or
a combination ofthese approaches. Use ofLID BMPs may reduce or eliminate the need for
conventional detention facilities. A variety ofBMPs to minimize impervious surfaces and to
manage stormwater have been developed and tested for use in Western Washington. These
BMPs and the overall LID approach are described in the LID Guidance Manual.
The menu of LID BMPs identified in the LID Guidance Manual are accepted for use in
stormwater site plans to address the minimum requirements for flow control and runoff
treatment in MMC 14.15.060, subject to the specifications,performance standards, and design
criteria in the LID Guidance Mannal, review and approval under this chapter, Chapter 19.49
MMC, as applicable, and the requirements and limitations below.
(l)The city engineer may approve the following LID BMPs to meet water quality
treatment requirements:
(a) Full dispersion. Sites that are approved for full dispersion,consistent with the
standards in the Technical Guidance Manual, are not required to provide water quality treatment.
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(b)Bioretention.Any stormwater runoffthat infiltrates through the imported soil mix in
an approved bioreterition facility will have received the equivalent oferihanced treatment.Where
bioretention is intended to fully meet treatment requirements,facilities shall be designed,using
an approved continuous runoff model, to infiltrate 60 percent ofthe developed two-year peak
flow.
(2) In addition to the requirements in MMC 14.15.065,applicants for LID BMPs shall
provide a site assessment.The site assessment shall include the following, unless waived or
modified by the city engineer:
(a) A mapped inventory of existing vegetation and description oftree cover and
understory;
(b) A mapped inventory ofwetlands and streams and required buffers under Chapter
19.24 MMC on the site;
(c) A survey prepared by a registered land surveyor or other licensed professional to
conduct surveys showing existing development,including utility infrastructure,on and adjacent
to the site,major and minor hydrologic features,including seeps, springs,closed depression
areas,drainage swales, and topographic relief at two-foot contours;
(d) The location ofall existing and proposed lot lines and easements;
(e) A soils report by a licensed geotechnical engineer or licensed engineering geologist.
The report shall identify:
(i)Underlying soils on the site,utilizing soil pits and soil grain analysis to assess
infiltration capability.The frequency and distribution oftest pits shall be adequate to direct
placement ofthe roads and structures away from soils that can most effectively infiltrate
stormwater;
(ii)Topographic features that may act as natural stormwater storage or conveyance and
underlying soils that provide opportunities for storage and partial infiltration;
(iii)Depth to groundwater;
(iv)Landslide hazard areas on the site and the distance to slopes over 25 percent or
landslide hazard areas within 500 feet ofthe site;
(f)Flood hazard areas on or adjacent to the site;
(g) SEPA Environmental Checklist.
(3)Additional studies may be required to address potential impacts to down-slope
properties.
(4)Restrictions on conversion of drainage facilities shall be recorded on the face ofthe
plat.
(5) A covenant shall be recorded with the Snohomish County auditor's office for each lot
containing or served by bioretention facilities in a form approved by the city attorney. The
covenant shall identify requirements and liability for preservation and maintenance of low
impact development facilities approved under this chapter and privately held in individual or
undivided ownership or intended for public ownership.
(6) An easement shall be granted for City access to low-impact development facilities on
private property to allow inspection,maintenance,and repair.
Section 3. Ch.14:16 MMC is hereby amended by amending MMC 14.16.015 and 14.16.040 to
read as follows:
14.16.015 Developer-installed storm water facilities located in city right-of-way.
The city may assume the operation and full or partial maintenance of developer-installed
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retention/detention or other drainage type treatment/abatement facilities located in the city right-
of-way or on city-owned property after the expiration ofthe two-year operation and maintenance
period if:
(1) All the requirements ofthis chapter have been fully complied with;
(2) The facilities have been inspected and approved by the engineer after two years of
operation.
14.16.040 Connections required.
(1) The owner of any property which is not connected to the public storm drainage system
shall be required to extend any storm drainage line which is
within 200 feet ofthe property,and to connect to and use the same for all developed portions
ofthe property,under any ofthe following circumstances:
(a) As a condition offinal approval of a subdivision;
(b) As a condition offinal approval ofa short subdivision;
(c) As a condition of final approval of a binding site plan for any mobile home park,
condominium,plarmed unit development,industrial park or shopping center;
(d) As a condition of any building,grading,paving or other development approval,
including rezones or conditional use permits,which will have a significant adverse impact upon
storm drainage; as determined by the public works director or designee.
(2) The public works director or designee may waive the requirement ofsubsection (1)of
this section on the following grounds:
(a)1fthe public works director or designee finds that the capacity or condition ofthe
existing public storm-drainage system is insufficient or inadequate to serve the subject property;
or
(b)Ifthe public works director or designee finds that it would cause a practical difficulty
to require the connection ofthe subject property to the public storm drainage system by reason of
circumstances which are unique to the property and not generally shared by other properties in
the vicinity;or
(c)Ifthe public works director or designee finds that proposed on-site stormwater BMPs
are adequate under the requirements ofthis Title.
No such waiver shall be granted which would be detrimental to the public health, safety,
welfare or environment,or which would be inconsistent with the long-range plans for the public
storm drainage system. In all cases where a waiver is granted,the property owner shall be
required to strictly comply with storm water retention/detention requirements of Chapter 14.15
MMC.
The decision of the public works director or designee regarding such waivers shall be
final,subject to appeal to the city council;provided,that in cases where a property owner has
applied for development approval which is to be ruled upon by the city council itself,waivers
referred to herein shall be determined by the city council after taking into consideration the
recommendation ofthe city engineer.
Section 4. Ch. 14.17 MMC is hereby amended by adding a new section MMC 14.17.035 and
amending MMC 14.17.090 to read as follows:
14.17.035 Maintenance ofbioretention facilities.
(l)Bioretention cells and swales which are located on private property or in public street
rights-of-way shall be cleaned,maintained and protected in continuous compliance with the
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standards and specifications ofthe city and any recorded maintenance agreements.
Responsibility for such work shall be borne by the owner ofthe underlying property or, in the
case offacilities within the public right-of-way,responsibility for such work shall be born by the
City.
(2)Property owners shall inspect approved bioretention facilities annually. Routine
maintenance such as trash removal, weeding, mulching and pruning ofbioretention areas and
swales shall be performed in accordance with the maintenance requirements outlined in the most
current edition ofthe LID Technical Guidance Manual for Puget Sound as needed, but at least
once yearly or as specified in City standards,maintenance specifications or any recorded
maintenance agreements.
(3) The city shall inspect approved bioretention facilities on an annual basis and monitor
the ongoing function ofboth private and public facilities. Routine maintenance such as trash
removal, weeding,mulching and pruning ofbioretention areas and swales shall be performed on
public facilities in accordance with the maintenance requirements outlined in the most current
edition ofthe LID Technical Guidance Manual for Puget Sound as needed, but at least once
yearly or as specified in City standards,maintenance specifications, or any recorded maintenance
agreements.
(4) No person shall cause or permit bioretention areas to be obstructed, filled, graded,Or
used for disposal ofdebris.
(5)If an LID facility required to be maintained by a private property owner fails to
perform as designed due to lack ofmaintenance,the City has the authority to perform the
necessary maintenance,and recoup the costs incurred.
(6) The city shall enforce the provisions ofthis section pursuant to the procedures
specified in MMC 14.17.040 through 14.17.080.
14.17.090 Exemptions.
(1)Storm water facilities owned and maintained by the Washington State Department of
Transportation in state highway rights-of-way which are regulated by and meet the requirements
of Chapter 173-270 WAC; the Puget Sound Highway Runoff Program, are exempted from the
requirements ofthis chapter.
(2) Except as specified by covenant or other instruroent recorded on the title ofadjacent
property,stormwater facilities located in city ofMarysville rights-of-way shall be maintained by
the city and are exempted from the requirements ofthis chapter.
(3) Requests for exemption shall be filed in writing with the public works director or designee
and shall adequately detail the basis for granting an exemption.
(4) The decision of the public works director or designee concerning a request for an
exemption shall be made in writing for review ofthe city council.
(5) The decision ofthe public works director or designee, as to an exemption or denial thereof,
may be appealed to the city council by filing written notice of appeal with the city clerk within
10 days ofservice ofthe public works director or designee's decision.
Section 5. Ch. 19.06 MMC is hereby amended by adding MMC 19.06.054 and amending
MMC 19.06.268 and 19.06.343 to read as follows:
19.06.054 Best Management Practice (BMP)
"Best management practices (BMPs)"refers to the schedules ofactivities,prohibitions of
practices,maintenance procedures,and-structural,and/or managerial practices,that when used
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singly or in combination,prevent or reduce pollution ofwater and have been approved by the
engineer. BMPs include, but are not limited to,infiltration,retention and/or detention,dispersion,
amended soils,biofiltration facilities,bioretention facilities, open ditches with check dams, filter
fabric strips,oil/water separators,wet ponds,constructed wetlands,erosion and sedimentation
control, and other treatment/abatement facilities.
19.06.268 Impervious surface.
"Impervious surface"means any nonvertical surface artificially covered or hardened so as to
prevent or impede the percolation ofwater into the soil mantle including,but not limited to,roof
tops,swimming pools, paved or graveled roads or parking areas and excluding landscaping and
surface water retention/detention facilities. Low impact development methods including,but not
limited to,pervious pavement systems, green roofs and the area within minimal excavation
foundations may reduce impervious area subject to consistency with the Low Impact
Development Technical Guidance Manual for Puget Sound and approval ofthe city engineer.
19.06.343 Net project area.
"Net project area"means the gross project area minus floodplains,utility easements 30 feet wide
or greater,publicly owned community facility land and right-of-way,stormwater detention
facility tracts or easements (unless underground and usable for recreation),private roads or
access easements,panhandles,and nontransferable critical areas (e.g.stream charmels) per MMC
19.24.370.Ifstormwater detention areas are designed and constructed to meet low impact
development standards,50%ofthe area used for detention may be counted as net project area.
Section 6. Ch 19.16 MMC is hereby amended by amending Subsection (4)of MMC
19.16.080 and MMC 19.16.100 and adding a new section MMC 19.16.115 to read as follows:
19.16.080 Descriptions of screens and landscaping types.
(4)Parking Area Landscaping,Type D.Landscaping that provides shade and visual relief
while maintaining clear sight lines within parking areas.Planting areas should contain a mixture
ofevergreen and deciduous trees, shrubs and groundcover in planting islands or strips having an
area ofat least 75 square feet and narrow dimension ofno less than fivefeet,Suggested planting
patterns which will achieve this standard are included in administrative guidelines prepared by
the plarming department.
19.16.100 Landscaping requirements for parking and outdoor display areas.
(I)Parking area, or outdoor storage areas fronting on a street right-of-way shall provide a
landscaped buffer, in accordance with Table I, along the entire street frontage except for
driveways;provided,that the plantings shall not obstruct the sight distance at street intersections.
(2)Additional plantings may be placed on street rights-of-way behind the sidewalk line if
the property owner provides the city with a written release ofliability for damages which may be
incurred to the planting area from any public use or right-of-way.
(3) Ten percent ofthe parking area, in addition to the required buffers above, shall be
landscaped with Type D landscaping;provided that:
(a) No parking stall shall be located more than 45 feet from a landscaped area;
(b) All landscaping must be located between parking stalls,between rows ofstalls, or at
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the end ofparking columns. The use of strips or islands as bioretention swales or cells is
encouraged,subject to approval by the city engineer. No landscaping which occurs between the
parking lot and a building or recreation area shall be considered in the satisfaction ofthese
requirements;
(c) A minimum ofone tree for every 120 square feet ofrequired internal landscaped area
shall be dispersed throughout the internal landscaped areas. Some trees may be grouped, but the
groupings should be dispersed.Existing trees may be used to meet this standard.If existing trees
are retained, each tree six inches or less in diameter counts as one tree. All trees will have a
minimum diameter ofthree inches. Trees between six inches and nine inches in diameter counts
as two trees.Each additional three inch diameter increment above nine inches counts as one tree;
(d)Parking lots containing less than 20 parking spaces need provide only perimeter
screening to satisfy the 10 percent area requirements;
(e) All landscaped areas shall be protected from vehicle damage by a six-inch protective
curbing. Wheel stops may be substituted when required to allow stormwater to pass;
(f) The landscaping requirements ofthis section may be modified ifa development is
located in an area where a special streetscape plan has been approved by the city.
19.16.115 Landscaping - Soil amendment.
All landscaped and lawn areas, except areas within the dripline ofpreserved trees, shall be
amended with four inches ofwell-composted organic matter mixed into the top eight inches of
soil or shall have an organic content ofbetween 8 and 13 percent dry weight and a pH suitable
for proposed plantings.Deeper soil amendment will provide improved growing medium and
increased water holding capacity.
Section 7. Ch 19.24 MMC is hereby amended by amending Subsection (10)of MMC
19.24.100 and Subsection (9)of MMC 19.24.230 to read as follows:
19.24.100 Wetland buffer areas.
(10)Stormwater management facilities, such as biofiltration swales and dispersion facilities,
may be located within the outer 25 percent of wetland buffers only ifthey will have no negative
effect on the functions and purpose the buffers serve for the wetland or on the hydrologic
conditions,hydrophytic vegetation,and substrate characteristics necessary to support existing
and designated beneficial uses.
19.24.230 Fish and wildlife habitat buffer areas.
(9)Stormwater management facilities, such as biofiltration swales and dispersion facilities, may
be located within the outer 25 percent ofbuffers only ifthey will have no negative effect on the
functions and purpose the buffers serve for the fish and wildlife habitat areas.Stormwater
detention ponds shall not be allowed in fish and wildlife habitat areas or their required buffers.
Section 8. Ch 19.28 MMC is hereby amended by amending Subsection (2)(g)of MMC
19.28.030 to read as follows:
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19.28.030 Minimum standards.
(2) Grading. The following are the minimum standards for grading unless otherwise
modified by an approved grading plan:
(g) The dufflayer and native topsoils shall be retained in an undisturbed state to the
maximum extent practicable in areas not intended for building pads, access ways or other
impervious surfaces.
Section 9. Ch 20.12 MMC is hereby amended by amending Subsection (2)of MMC
20.12.010 to read as follows:
20.12.010 Preapplication requirements.
(2)Preliminary Drawing.
(a) The applicant shall provide an accurate preliminary drawing to scale showing lot
layout,existing and proposed building location, size, access, utilities, open space,water sources,
adjacent land use, and five-foot contours. This drawing must be provided before a pre-
application meeting will be scheduled.
(b)Iflow-impact development techniques,including bioretention,dispersion or
infiltration are proposed to manage stormwater,the applicant shall provide a site assessment
consistent with the requirements in MMC 14.15.061.
(c) The applicant shall also provide a legal description ofthe property and a vicinity map.
Section 10. Ch 20.24 MMC is hereby amended by amending Subsections (2) and (3)of
MMC 20.24.070,Subsection (4)of MMC 20.24.090,Subsection (l)of MMC 20.24.110, and
MMC 20.24.250 to read as follows:
20.24.070 Landscaping requirements.
Landscaping shall be in conformance with Chapter 19.16 MMC,Development Standards-
Landscaping;provided,that for all newdivisions of land, the applicant shall provide a
landscape/reforestation plan that will include, but not be limited to, the following:
(2) Yard trees at a rate oftwo per lot. Yard trees shall include at least one evergreen tree
which is native to the Northwest region. Yard trees shall be a minimum ofone and one-quarter
inches in caliper and six to eight feet high for deciduous, and six feet high for evergreens. Lots
that include retained trees will not be required to provide yard trees.
(3) Where the community development director determines that it is not feasible and/or
desirable to plant the required lot trees, the applicant shall pay into the city tree fund an amount
ofmoney approximating the current market value ofthe trees, as well as labor costs for
installation ofsaid trees, that would otherwise be required. The city shall use the city tree fund
for the purpose of acquiring,maintaining,and preserving wooded areas, and for planting and
maintaining trees within the city.
20.24.090 Street improvements.
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(4) The use ofcurvilinear streets and loop access roads shall be encouraged where such
use will result in a more desirable layout.
20.24.110 Drainage improvements.
(1)Drainage improvements shall be required as specified in MMC Title 14. Use oflow
impact development methods to mimic predevelopment hydrologic functions and manage
stormwater through natural processes is encouraged.
(2)Drainage Easements.When a subdivision or short subdivision is traversed by a
watercourse,drainageway,channel or stream, the applicant shall provide a drainage easement or
drainage right-of-way conforming substantially to the lines ofthe watercourse or drainageway.
The easement or drainage right-of-way shall be maintained in its natural state with proper
setback and landscaping as approved by the city.
20.24.250 Site improvements designated.
Site improvements shall include, but are not limited to: grading of entire width ofstreet
rights-of-way,asphalt/concrete surfacing ofroadways (as per city standards contained in the
street code), curbs, gutters and sidewalks constructed according to the street code, and
construction ofdrainage facilities included in the preliminary plat. The requirement for curbs and
gutters may be waived by the City Engineer,ifbioretention facilities are approved for managing
stormwater runoff from the street. Flow through curbs may be required by the City Engineer.
The developer shall request inspection ofthe improvements by the city engineer or his designee
at the following times:
(I)Erosion control measures are installed;
(2) Rough grading is complete and prior to placing pit run;
(3)Stormwater management facility completion;
(4)Roadway and frontage improvement completion;
(5) When all improvements,including monuments, have been placed.
All improvements which do not meet city standards shall be immediately replaced or repaired
prior to proceeding. The city engineer, or his designee, will inform the developer in writing of
any improvements which are not acceptable.
Section II.Title 19 MMC is hereby amended by adding a new chapter Ch. 19.49 MMC
to read as follows:
CHAPTER 19.49
LOW IMPACT DEVELOPMENT
Sections:
19.49.010 Purpose.
19.49.020 Applicability.
19.49.030 Protected native vegetated area.
19.49.040 Preservation and amendment oftopsoils.
19.49.050 Stormwater management.
19.49.060 Maximum impervious surfaces.
19.49.070 Dimensional standard modifications.
19.49.080 Review process.
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19.49.010 Purpose.
The purpose of this chapter is to permit design flexibility and provide performance criteria for
low impact development. Low impact development (LID) is a stormwater management and land
development strategy utilized in site design and construction that emphasizes conservation and
use of on-site natural features integrated with engineered, small-scale hydrologic controls to
mimic natural hydrologic functions.Implementation of LID benefits streams, lakes, and Puget
Sound by moderating the impacts of stormwater runoff generated by the built enviromnent. LID
techniques may supplant or augment traditional, structural stormwater management solutions.
Low impact best management practices (BMPs) are described in the Low Impact Development
Technical Guidance Manual for Puget Sound, 2005,published by the Puget Sound Action Team.
LID objectives are:
(I)To retain or restore native forest cover to capture, infiltrate, and evaporate all or a portion of
the rainfall on a site;
(2) To confine development to the smallest possible footprint and minimize land disturbance and
site grading;
(3) To preserve or restore the health and water-holding capacity ofsoils;
(4) To incorporate natural site features that promote stormwater infiltration;
(6) To minimize all impervious surfaces and especially those that drain to conventional piped
conveyance;
(7) To manage stormwater through infiltration,bioretention,and dispersion; and
(8) To manage stormwater runoff as close to its origin as possible in small, dispersed facilities.
19.49.020 Applicability.
(1) Conformance with this chapter shall be required:
(a) For sites designated as a low impact development special district or overlay zone
under the authority ofChapter 19.46 MMC; or
(b)Where specified in an adopted basin plan pursuant to MMC 14.15.050(9); or
(c) When a site has committed to being an LID project pursuant to MMC 14.15.062.
(2) Modifications of this chapter are allowed for any proposed development subject to a
determination of the applicable review authority that the proposal substantially furthers all
objectives in MMC 19.49.010.
19.49.030 Protected native vegetated areas.
A portion ofthe site shall be preserved as protected native vegetated area.
(1) Protected native vegetated areas shall be designated in the following ratios:
(a) Residential Developments: Proposed at 6.0 dwelling units per acre or less shall
preserve 35 percent ofthe site as native growth areas.
(b)Residential Developments: Proposed at more than 6.0 dwelling units per acre shall
preserve 20 percent ofthe site as native growth areas.
(c) Commercial Developments: Shall preserve 10 percent of the site as native growth or
landscaped areas.
(d) Improvements within existing public rights-of-way are exempt.
(2) For the purposes of calculating required area, submerged lands and sensitive areas and
buffers required to be protected pursuant to Chapter 19.24 MMC shall not be included.
(3) Protected native vegetated areas shall be forested. Where existing vegetation provides
minimal canopy cover or where nonnative or invasive plant species provide the predominant
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cover, a planting plan shall be prepared that includes plant densities that are not less than five
feet on center for shrubs and 10 feet on center for trees. This requirement does not apply to
preserved wetlands. All plant species shall be native. Seventy percent of planted trees shall be
deciduous species of at least one and one-half inch in caliper. Evergreen trees shall be six feet in
height. The community development director may modify the requirements of this section based
on site conditions.
(4) Clearing limits shall be surveyed, staked, and fenced with erosion control and/or clearing
limits fencing prior to any construction work, including grading and clearing.
(5) Trees shall not be removed from areas proposed to meet the protected native growth area
requirement during site development.
(6) Monitoring and maintenance ofplants shall be required in accordance with MMC 19.24.270.
(7)Development within protected native vegetated areas shall be limited to biofiltration swales,
stormwater dispersion facilities, pervious pedestrian trails, and approved surface water
restoration projects.Activities within the protected native growth areas shall be limited to
passive recreation, removal ofinvasive species, amendment ofdisturbed soils consistent with all
applicable regulations, and planting of native vegetation. Development shall be consistent with
critical areas requirements and restrictions in Chapter 19.24MMC.
(8) A permanent protective mechanism shall be legally established to ensure that the required
protected native vegetated area is preserved and protected in perpetuity in a form that is
acceptable to the city and filed with the county auditor's office. A permanent protected native
vegetated area shall be established using one ofthe following mechanisms.
(a)Placement in a separate non-building tract owned in common by all lots within a
subdivision;
(b) Covered by a protective easement or public or private land trust dedication;
(c) Preserved through an appropriate permanent protective mechanism that provides the
same level ofpermanent protection as subsection (a)of this section as determined by the
community development director or hearing examiner.
(9) Restrictions on the future use ofthe protective native vegetated area shall be recorded on the
face ofthe final plat, short plat, binding site plan, or site plan.
19.49.040 Preservation and amendment oftopsoils.
The duff layer and native topsoils shall be retained in an undisturbed state to the maximum
extent practicable.
(l)Any duff or topsoil removed during grading shall be stockpiled on-site in a designated,
controlled area not adjacent to public resources and critical areas. The material shall be reapplied
to other portions ofthe site where feasible.
(2) Except as otherwise provided in subsection (3), areas that have been cleared and graded or
subject to prior disturbance shall be amended. Prior disturbance shall include soil compaction or
removal of some or all of the duff layer or underlying topsoil. The amendment shall take place
between May 1 and October 1. Replaced topsoil shall be a minimum of 8 inches thick, unless the
applicant demonstrates that a different thickness will provide conditions equivalent to the soil
moisture holding capacity native to the site. Replacement topsoil shall have an organic content of
between 8 and 13percent dry weight and a pH suitable for the proposed landscape plants.
(3) This section does not apply to areas within the dripline of existing trees proposed for
retention, or areas that, at project completion, are covered by an impervious surface, incorporated
into a drainage facility or engineered as structural fill or slope.
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19.49.050 Stormwater management.
LID projects shall use infiltration, dispersion, and bioretention to the maximum extent
practicable to manage stormwater runoff generated on-site.
(l)Infiltration shall be used except where a site assessment demonstrates that infiltration is not
feasible due to site conditions or due to probable risk to groundwater or to other property.
(3) LID projects shall meet the minimum peak and duration flow control standards per the
Department of Ecology Stormwater Management Manual for Western Washington, current city
adopted edition.
(4) Flow control facilities may be reduced in size through compliance with LID Technical
Guidance Manual Section 7.2.2 - full dispersion for all or part ofthe development site.
(5) Water quality treatment BMPs shall be provided to treat 91-percent of the annual runoff
volume per the Department ofEcology standards.
(6) All site soils disturbed during construction shall be rehabilitated to the specifications of
Integrated Management Practice 6.2 of the Low Impact Development Technical Guidance
Manual for Puget Sound (2005).
TABLE 19.49.060-1 Pond Reduction Pond Reduction
(Infiltration <0.30 inlhr or (Infiltration of =0.30
less) 5,6 inlhr or more)5,6
Rural Residential 100%100%
Urban Residential < 6.0 50%60%
Dwelling Units per Acre
Urban Residential ~6.0 50%60%
Dwelling Units per Acre
Multi-Family 40%80%
Commercial 40%80%
Roads 50%50%
The volume reduction in the Table 19.49.060-1represents a reduction as compared to the volume
needed for a detention pond serving a standard development. Notes (a)-(d) below apply to the
table.
(a)Infiltration rates are as measured in the field at the proposed LID location using techniques
recommended in the Stormwater Management Manual for Western Washington and the Low
Impact Technical Guidance Manual for Puget Sound.
(b) Multi-family projects are those projects containing more than three dwelling units attached in
a single structure, regardless ofownership mechanism.
(c) All projects with Type A (outwash) soils shall infiltrate 100percent of runoff.
(d) Stormwater discharges shall match developed discharge durations to pre-developed durations
for the range ofpre-developed discharge rates from 50 percent of the 2-year peak flow up to the
full 50-year peak flow.
19.49.060 Maximum impervious surfaces.
LID projects shall limit impervious surface coverage as follows:
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(1)New impervious surface shall not exceed 70 percent ofthe site for nonresidential uses listed
in MMC 19.08.040, MMC 19.08.050, MMC 19.08.060, MMC 19.08.070,MMC 19.08.080,
MMC 19.08.090, MMC 19.08.100, and hotel/motel uses.
(2)New impervious surface coverage shall not exceed the maximum limits in the following table
for residential uses listed in MMC 19.08.030 except hotel/motel uses:
TABLE 19.49.070-2 Maximum Percent Impervious Area based on Residential
Density
Dwellina Units Per Acre Maximum %Impervious
<1.4 dulac 10%
1.5-2.4 dulac 15%
2.5-3.4 dulac 20%
3.5-4.9 dulac 30%
5.0-6.9 dulac 35%
7.0-9.9 dulac 40%
10.0 dulac or greater 60%
19.49.070 Density bonus and dimensional standard modifications.
(1)Development may be granted a density incentive pursuant to Chapter 19.26 MMC.
(2) The city, in its discretion, may allow the following modifications to residential dimensional
standards in MMC 19.12.030 to meet the protected native growth area requirement in MMC
14.49.040 and to accommodate density bonuses received pursuant to Chapter 19.26 MMC:
(a)Minimum lot area may be reduced for single family dwellings to 4,000 square feet in
the R-6.5 zone and 3,500 square feet in the R-8 zone.
(b)Minimum lot width may be reduced to 40 feet in the R-4.5 and R-6.5 zones.
(3)Modifications requested under this section shall require a justification of necessity according
to the provisions of(1)above.
19.49.080 Review process.
(1)Except as specifically modified by this chapter, all development occurring under this chapter
shall be subject to all applicable requirements and processes ofthe Marysville Municipal Code.
(2)All standards and requirements of this chapter shall be conditions of approval for the
underlying development permits.
(3)All development proposed under this chapter shall be subject to the site assessment
requirements of MMC 14.15.061(2).Applicants are encouraged to meet with public works and
planning staff following completion of the site assessment and prior to site design to discuss
additional analysis that may be required to support the use of LID BMPs,preliminary
recommendations on meeting the stormwater regulations,and low impact options for site design.
Section 12. Severability.If any section,subsection,sentence, clause, phrase or work of
this ordinance should be held to be invalid or unconstitutional by a court of competent
jurisdiction,such invalidity or unconstitutionality thereof shall not affect the validity or
constitutionality of any other section,subsection,sentence, clause,phrase or word of this
ordinance.
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CITY OF MARYSVILLE
By:
DENNIS L KENDALL,MAYOR
Approved as to r..~n
By:~J(.(~
'GRANT K.WEED,CITY ATTORNEY
Date ofPublication:5/1l.R J07rI
Effective Date:5/7.-1/0J-__
(5 days afte~publication)
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