This title shall be known as the Storm and Surface Water Utility Code and the Woodway storm and surface water utility shall be referred to as the "utility" throughout this chapter.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Public Health, Safety and Welfare. Establishment of this utility is necessary in order to promote public health, safety and welfare by implementing a management approach to surface and stormwater issues. This management approach includes the following elements: planning, land use regulation, construction of facilities, maintenance, and provision of storm and surface water management services.
B.
Rates and Charges. This code establishes rates and charges, which shall be uniform for the same class of customer and service, and establishes methods of development and construction. The purpose of the rates and charges established herein is to provide a method for payment of all or any part of the cost and expense of storm and surface water management services and to secure financing for such services. Imposition of these rates and charges is also necessary in order to promote public health, safety and welfare by minimizing uncontrolled surface and stormwater, erosion and water pollution; to preserve and enhance the many values of the Town's natural drainage system including water quality, open space, fish and wildlife habitat, recreation, and to provide for the management and administration of storm and surface water.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
This code constitutes an exercise of the police power of the Town to promote public health, safety and welfare, and its provisions shall be liberally construed for the accomplishment of that purpose.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
For purposes of this chapter, the definitions in the State of Washington Department of Ecology's "Stormwater Management Manual for the Puget Sound Basin" (the technical manual, 2005 Edition) and all amendments and additions thereto, are adopted by this reference except as stated below. Words used in the singular include the plural, and words used in the plural include the singular. Words used in the masculine gender include the feminine, and words used in the feminine gender include the masculine. Unless otherwise defined herein, the definitions in Chapter 11.02 shall apply.
A. "Capital facilities charge"
means the fee applied to properties at the time of development enabling the Town to recover the prior public investment in infrastructure capacity installed to accommodate additional storm and surface water runoff generated by future development.
B. "Developed parcel"
means any parcel or parcels of property altered from the natural state by the construction, creation, or addition of impervious surfaces.
C. "Director"
means the Mayor or their designee.
D. "Drainage basin"
means the geographic region within which water drains into a particular aquatic system or other body of water.
E. "Drainage facility"
means the system of collecting, conveying, and storing storm and surface water runoff. Drainage facilities shall include, but not be limited to, all storm and surface water conveyance and containment facilities including streams, pipelines, channels, ditches, wetlands, closed depressions, infiltration facilities, retention/detention facilities, erosion/sedimentation control facilities, and other drainage structures and appurtenances, both natural and constructed.
F. "Impervious surface"
means a surface that greatly reduces or stops the transmission of water, including, but not limited to, asphalt and Portland cement paving, paving blocks, compacted soils and gravel for parking areas, rooftops, or any manmade material that impedes the flow of water and is permanently fixed to the ground. Lattice work paving systems that have a portion of their areas open to the subgrade shall not be considered impervious as to the portion that is open.
G. "Maintenance"
means the act or process of cleaning, repairing or preserving a system, unit, facility, structure or equipment.
H. "Natural surface water drainage system"
means such landscape features as streams, swales, lakes and wetlands.
I. "Parcel"
means the smallest separately segregated unit or plot of land having an identified owner, boundaries and surface area that is documented for property tax purposes and given a tax lot number by the Snohomish County Assessor.
J. "Person"
means any individual, partnership, corporation, association, organization, cooperative, public or municipal corporation, agency of the State or local government unit, however designated.
K. "Property owner of record"
means a person or persons shown in the records of the County Assessor to be the owner of property.
L. "Rate category"
means the classification in this chapter given to a parcel in the service area based on the land use designation of the parcel.
N. "Service charges"
means charges to property owners for storm and surface water management services.
O. "Storm and surface water management services"
means the services provided by the utility, including, but not limited to, planning, facility design and construction, facilities maintenance, regulation, financial administration, and public involvement.
P. "Storm and surface water"
means the water originating from rainfall and other precipitation that is found on the ground surface and in drainage facilities, streams, springs, seeps, ponds and wetlands.
Q. "Storm and surface water management system"
means constructed drainage facilities and any natural surface water drainage features that collect, store, control, treat and/or convey storm and surface water runoff.
R. "Storm and surface water program"
means a plan and all implementing regulations and procedures including, but not limited to, capital projects, land use management regulations, and any other measures adopted by the Town for managing storm and surface water management facilities and features within the Town.
S. "Undeveloped parcel"
means any parcel that has not been altered by construction, and/or creation or addition of impervious surface(s), and is not otherwise considered a developed parcel.
T. "Undeveloped vegetated area"
means an area of primarily native vegetation that is unaltered by construction or other land alteration activity.
(Ord. 07-477 (part), 2007; Ord. 11-527 § 1, 2011; Ord. 17-578 § 1 (Exh. D (part)), 2017; Ord. 24-654 § 3 (Exh. C), 2024)
The storm and surface water management fund is created. All service charges shall be deposited in this fund, to be used only for the purpose of paying all or any part of the cost and expense of providing storm and surface water management services, or to pay or secure the payment of all or any portion of any financing for such purpose.
(Ord. 07-477 (part), 2007; Ord. 11-527 § 2, 2011; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The utility herein created shall be administered and enforced by the Director. The Director is authorized to specify such storm and surface water facility operation, maintenance and performance standards as necessary to implement the requirements of this code and carry out the duties of the Director.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Floods from stormwater runoff that exceed the capacity of drainage facilities constructed and maintained by funds made available under this chapter may occasionally occur. The Town's adoption of this code does not imply that property liable for the service charges shall always be free from flooding. Further, this code does not purport to reduce the need or the necessity for any property owner to obtain flood insurance.
B.
This chapter shall be administered and enforced for the benefit of the health, safety and welfare of the general public, and not for the benefit of any particular person or class of persons.
C.
No provision of or any term used in this chapter is intended to impose any duty upon the Town or any of its officers or employees which would subject them to damages in a civil action.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
Upon presentation of proper credentials, the Director may, with the consent of the owner or occupier of the premises or property, or pursuant to a lawfully issued warrant, enter at reasonable times any property or premises subject to the consent or warrant, in order to implement this code.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Effective July 1, 2007, the Town shall impose on all developed parcels located within the Town limits a storm and surface water service charge.
B.
A system and structure of storm and surface water service charges is established in accordance with the provisions of this chapter.
C.
The Town and other jurisdictions may enter into interlocal agreements allowing the other jurisdictions to provide billing and other management services.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Developed Parcels. Developed parcels contribute to an increase in runoff to the storm and surface water management system. This increase in runoff results in the need to establish rates and charges to finance the Town's activities in storm and surface water management.
B.
Undeveloped Parcels. Undeveloped parcels are to be exempt from the storm and surface water utility service charges. Upon issuance of a building permit, the full service charge for that property shall begin to be collected in accordance with this chapter and a capital facilities charge in accordance with Section 11.01.150 shall also be collected.
C.
Exemptions.
1.
No Benefit/No Burden. Parcels receiving no benefit from or placing no burden on the storm and surface water management system or programs are exempt from storm and surface water service charges.
2.
Private Systems. Properties with private stormwater management systems may be eligible for a reduction in the stormwater service charge by the amount of the charge attributable in excess of the base fee. To realize this rate reduction, the property owner must be able to demonstrate, to the satisfaction of the Director through certification by a licensed engineer experienced in stormwater management, that sixty-five percent of the developed parcel is retained in an undeveloped vegetated area and the site stormwater management system achieves a runoff rate less than or equal to that which would be achieved by a maximum of ten percent impervious surface coverage on the developed parcel; provided, that all life, safety, health and environmental considerations (including but not limited to aquifer recharge areas and bluff protection areas) are met. The property owner shall reimburse the Town for all costs incurred in performing the evaluation of the engineering certification provided by the property owner.
3.
Road System. All Town public roads and rights-of-way are exempt from storm and surface water service fees.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Utility Service Charges. The storm and surface water utility service charges shall be as set forth in the Town’s fee schedule authorized by Section 3.32.010, as now or hereafter amended. The service charges established in the Town’s fee schedule shall increase annually by the amount authorized by Council resolution or the greater of three percent or the June-to-June CPI-U for Seattle-Tacoma-Bellevue, with the calculated fees rounded up to the nearest whole number. The Clerk-Treasurer is authorized to update the Town’s fee schedule annually consistent with a resolution or calculation provided by this subsection.
B.
Town Reserves the Right to Make Changes. The Town Council recognizes that future state and/or federal stormwater requirements, as well as increased costs in identified projects or additional costs of new projects, may require additional adjustments to the service charge structure and/or service charges. Because not all needs or requirements of the utility are foreseeable, the Council retains the ability and authority to modify service charges and the service charge structure as needed.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017; Ord. 24-654 § 1 (Exh. A), 2024; Ord. 2025-668, 6/2/2025)
A.
Any person billed for service charges may file a "request for rate adjustment" with the utility within two years of the date from which the bill was sent. However, filing of such a request does not extend the period for payment of the charge.
B.
Requests for rate adjustment may be granted or approved by the Director only when the following conditions exist:
C.
The property owner shall have the burden of proving that the rate adjustment sought should be granted.
D.
Decisions on requests for rate adjustments shall be made by the Director based on information submitted by the applicant within thirty days of the adjustment request except when additional information is needed. The applicant shall be notified in writing of the Director's decision. If an adjustment is granted that reduces the charge for the current year or two prior years, the applicant shall be credited the amount overpaid in the current and two prior years.
E.
If the Director finds that a parcel has been undercharged, then either an amended bill shall be issued that reflects the increase in the service charge or the undercharged amount shall be added to the next bill. This amended bill shall be due and payable in accordance with a payment schedule approved by the Director. The Director may include in the bill the amount undercharged for two previous billing years in addition to the current bill.
F.
Decisions of the Director on requests for rate adjustments shall be final unless, within thirty days of the date the decision was mailed, the applicant files an action in the Snohomish County Superior Court.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The Town may administer the billing and collection services required to implement this chapter, it may contract for such services or it may enter into interlocal agreements with other governments for this purpose. All billing and collection services shall be implemented as follows:
A.
All property subject to service charges shall be billed semiannually for the previous six-month period based upon the applicable property rate category.
B.
Adjustments to the annual service charge may be made when property is annexed into the Town. The service charge for the billing year during which annexation occurs shall be subject to a proration formula that may be included in an interlocal agreement between the Town and Snohomish County.
C.
All semiannual utility bills shall be paid on or before the last day of the month in which the bill is issued. In the event any semiannual utility payment is not received by close of business on the fifth day of the month after the bill is due and the account becomes delinquent, a penalty of five dollars per month shall be added to any outstanding balance until the bill is paid in full.
D.
All final prorated stormwater utility bills shall be due thirty days after the issuance date. In the event any final utility payment is not received by close of business on the thirty-fifth calendar day after issuance and the account becomes delinquent, a penalty of five dollars per month shall be added to any outstanding balance until the bill is paid in full.
E.
The Mayor or Mayor's designee may waive one late fee per twelve-month period if the waiver is requested in writing by the account holder, provided the account holder has not had a late fee waived during the previous twelve months. Fees waived in accordance with this subsection and Section 3.32.020(G) count toward the one allowable waiver per twelve-month period.
F.
The Mayor or Mayor's designee may waive late fees and interest charges for unpaid fee balances of one dollar or less.
(Ord. 07-477 (part), 2007; Ord. 08-490 § 1, 2008; Ord. 10-519 § 1, 2010; Ord. 17-578 § 1 (Exh. D (part)), 2017; Ord. 19-602 § 1, 2019; Ord. 22-637 § 1, 2022)
Nothing contained in this chapter shall be construed as a waiver of liens, and the Town shall have all rights to liens as provided in Chapter 35.67 RCW, as the same exists or may hereafter be amended, or any other rights to enforce the collection of storm and surface water service charges as may from time to time be provided in State law. Liens for storm and surface water service charges shall be effective for a total not to exceed one year's delinquent charges without the necessity of any writing or recording of the lien with the County Auditor. The lien shall have superiority as established by RCW 35.67.290. There shall be added to the delinquent amounts and interest all costs and expenses incurred by the Town in compelling payment of the same.
(Ord. 07-477 (part), 2007; Ord. 11-526 § 1, 2011; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
The purpose of this section is to establish storm and surface water capital facilities charges for all development activity. The capital facilities charge is established to recover the fair share of the prior public investment in infrastructure capacity installed to accommodate the additional storm and surface water runoff generated with construction of new development. The storm and surface water utility capital facilities charges shall be as set forth in the Town's fee schedule authorized by Section 3.32.010, as now or hereafter amended.
B.
At the time of building permit issuance, a capital facilities charge will be collected and the service charge for that parcel shall begin to be collected in accordance with the Town storm and surface water service charge structure.
(Ord. 07-477 (part), 2007; Ord. 17-578 § 1 (Exh. D (part)), 2017; Ord. 24-654 § 2 (Exh. B), 2024)
[1]
Prior ordinance history: Ords. 307 and 04-431.
For purposes of this chapter, the definitions in the State of Washington Department of Ecology's "Stormwater Management Manual for the Puget Sound Basin" (The Technical Manual, 2005 Edition) and all amendments and additions thereto, are hereby adopted by this reference, except as stated below:
A. "Administrator"
means the Mayor or that person's duly authorized designee with input from the Town's Engineer.
B. "Allowable discharge"
means the rate at which runoff may be released from a project.
C. "Aquifer recharge area"
means an area that contributes water to an aquifer via surface flow, interflow, and groundwater flow. The Town of Woodway has a critical area map showing portions of the Town that are in the aquifer recharge area for the Deer Creek water supply.
D. "Assessed value"
means the value of the existing improvements, excluding land, as listed in the current records of the Snohomish County Assessor. Alternately, the proponent may provide current appraisal information and request that it be substituted for the Assessor's records.
E. "Basin" or "drainage basin"
means an area from which surface runoff is concentrated, usually to a single point, such as the mouth of a stream.
F. "Basin plan"
means a plan adopted by the Town, which specifies capital improvements, regulations and policies for managing drainage in a basin.
G. "Best management practice" or "BMP"
means structures, conservation practices and/or regulations that improve runoff quality or reduce the impact of development on runoff quantity.
H. "Biofilter"
means a vegetated surface over which runoff traverses at a uniform depth and velocity.
I. "Biofiltration"
means the process by which pollutant concentrations in runoff are reduced by filtration through vegetation.
J. "Buffer"
means a zone that is an integral part of a stream, wetland ecosystem, or landslide hazard area, and that protects aquatic resources by providing:
K. "Capital improvement program"
means a list of prioritized and scheduled construction projects and their costs.
L. "Check structure"
means a rock, earthen or log dam used in channels to reduce water velocities, promote sediment deposition, and/or enhance infiltration.
M. "Class or hydrologic group A, B, C, D soils"
means the United States Soil Conservation Service's soil classification according to hydrologic characteristics.
N. "Clean impervious surface"
means an impervious surface on which the frequency or probability of contamination from motor vehicles or from the routine handling of hazardous materials is minimal. Such surfaces may include, but are not limited to, rooftops, sidewalks, dedicated play areas and emergency fire lanes.
O. "Closed basin"
means a basin for which there is no surface water outlet.
P. "Construction cost"
means the estimated cost of the development or redevelopment including labor, material, sales tax, equipment, supervision, overhead, profit, etc. The estimated cost must be approved by the Town Engineer prior to clearing and grading permit issuance.
Q. "Conveyance"
means a mechanism or device for transporting water including, but not limited to, pipes, natural and/or manmade channels, culverts, gutters and manholes.
R. "Dead storage"
means the volume of storage in a facility below an outlet that does not drain after a storm event.
S. "Design event"
means an amount of rainfall in a specified period of time and occurring in specified volume increments over time that is used in the design of facilities.
T. "Detention facility"
means a facility such as a pond, vault or pipe in which surface and stormwater is temporarily stored.
U. "Detention pond"
means a detention facility that is an open pond.
V. "Development"
means any project that requires a drainage and erosion control plan under this chapter.
W. "Direct discharge"
means undetained discharge from a proposed project to a major receiving water. The only major receiving water in the Town of Woodway is the Puget Sound. Major receiving waters do not include side channels, spring- or groundwater-fed streams, or wetland habitats that provide salmonid spawning or rearing habitat that may be connected or adjacent to the Puget Sound. Direct discharges are governed by the guidelines found in Appendix I-E of 2005 DOE Manual. All elements of the conveyance system must be comprised of manmade conveyance elements (pipes, ditches, outfall protection, etc.) and shall be within public right-of-way or a public or private drainage easement.
X. "Disturbed area"
means an area that is not protected by covenants or other legal protection from alteration of its natural state.
Y. "DOE stormwater manual"
means the 2005 Edition of the State of Washington, Department of Ecology's Stormwater Management Manual for Western Washington.
Z. "Drainage and erosion control plan"
means all submittals required by the Town to evaluate a major project in order to satisfy the requirements of this chapter, and, in addition, the plans and specifications for construction of drainage and erosion control facilities for the project. A drainage and erosion control plan includes a drainage report, a maintenance and source control plan, drawings and specifications, and an erosion and pollution control plan as described in Section 11.02.110.
AA. "Drawings of record"
means engineering plans that document changes made to a project during construction.
BB. "Effective impervious area"
means those impervious surfaces that are connected via sheet flow or discrete conveyance to a drainage system. Impervious surfaces on residential development sites are not considered effective impervious area if the runoff is dispersed through at least one hundred feet of native vegetation in accordance with BMP T5.30, "Full Dispersion," as described in Chapter 5 of Volume 5 of the 2005 DOE Stormwater Management Manual for Western Washington.
CC. "Existing conditions"
means the predeveloped (forested) condition of the site.
DD. "Impervious surface"
means a surface that greatly reduces or stops the transmission of water, including, but not limited to, asphalt and Portland cement paving, paving blocks, compacted soils and gravel for parking areas, rooftops, or any manmade material that impedes the flow of water and is permanently fixed to the ground. Lattice work paving systems which have a portion of their area open to the subgrade shall not be considered impervious as to the portion that is open.
EE. "Low impact development"
means a stormwater management strategy that emphasizes conservation and use of existing natural site features integrated with distributed, small-scale stormwater controls to more closely mimic natural hydrologic patterns in residential, commercial, and industrial settings.
FF. "Bluff"
means the land designated as a geologic hazard area on the Town's 2015 Comprehensive Plan critical areas maps or any area that has been documented to have unstable soils.
GG. "Bluff project"
means a proposed project:
HH. "Natural channel"
means a stream, creek, river, lake, wetland, estuary, gully, swale, ravine or any open conduit in which water concentrates and flows intermittently or continuously.
II. "Off-site drainage"
means drainage from adjacent property that enters the proposed project site in other than defined natural channel.
JJ. "Outfall"
means the point at which water flows from manmade conduit, channel or drain into a water body or other natural drainage flow.
KK. "Person"
means any individual, partnership, corporation, association, organization, cooperative, public or municipal corporation, agency of the State or local government unit, however designated.
LL. "Pollution generating impervious area"
means those impervious surfaces considered to be a significant source of pollutants in stormwater. Such surfaces include those that are subject to vehicular use, industrial activities, or storage of erodible or leachable wastes or chemicals, and that receive direct rainfall or the run-on or blow-in of rainfall.
MM. "Post-development conditions"
means the condition of a site after the project has been constructed.
OO. "Predevelopment conditions"
means the pristine state of forested land before any development has occurred.
PP. "Project"
means the proposed action that leads to addition or reconstruction of impervious surface, addition of value to a property, or disturbance of the ground surface.
QQ. "Project engineer"
means the engineer who is responsible for the design of drainage facilities and who will affix his seal on the project's drainage and erosion control plan.
RR. "Project site"
means the parcel or parcels on which the permitted activity occurs including adjacent parcels with existing development which the Administrator determines is part of the project.
SS. "Proponent"
means the person or legal entity holding title to the property or having a sufficient interest in the property to propose the project.
TT. "Ravine"
means a narrow gorge normally containing steep slopes and is deeper than ten vertical feet, as measured from the centerline of the ravine to the top of the slope.
VV. "Receiving waters"
means a natural water feature protected as such by law including but not limited to wetlands, lakes, marine water bodies, intermittent streams, natural swales and gullies, and all waters of the United States.
WW. "Redevelopment"
shall be defined per the definition described in Section 3.3 of the 2005 DOE Stormwater Manual. Also, remodels to an existing project site for which the Administrator determines that because of scientific reports, maintenance records, and/or a complaint history a severe downstream water quality degradation, flooding or habitat loss problem occurs shall be considered as redevelopment.
XX. "Retention facility"
means a facility with no outlet to surface water intended to discharge to groundwater.
YY. "Retention facility permeability"
means the average field-saturated percolation rate of an infiltration facility after construction, as determined by field and/or laboratory work conducted by a soils scientist.
ZZ. "Retention pond"
means a retention facility that is an open pond.
AAA. "Retention/detention facility"
means either a facility with an outlet to surface water intended to discharge partially to groundwater and partially to surface water, or a retention facility or a detention facility.
BBB. "Revetments"
means the facing used to sustain an embankment.
EEE. "Site"
means one or more parcels on which the project is proposed to be located, including those parcels on which existing development is located that the project proposes to expand.
FFF. "Soils scientist"
means a person certified by the American Registry of Certified Professionals in Agronomy, Crops, and Soils as a soils scientist, or someone with equivalent education and experience in soils science.
GGG. "Standard plans"
means the most recent edition of Standard Plans for Road, Bridge, and Municipal Construction published by the Washington State Department of Transportation, in cooperation with the American Public Works Association.
HHH. "Standard specifications"
means the most recent edition of Standard Specifications for Road and Bridge and Municipal Construction published by the Washington State Department of Transportation, in cooperation with the American Public Works Association.
III. "Stormwater"
means precipitation that falls on property and does not naturally percolate into the ground or evaporate, but instead flows via overland flow, channels or pipes into a defined surface water channel, or a constructed infiltration facility. "Stormwater" includes washdown water and other waste that enters the drainage system.
JJJ. "Subbasin"
means a drainage area that drains to a point contained within a larger basin.
LLL. "Undisturbed area"
means property in its base line natural state, which is protected as such by covenant.
MMM. "Uninterruptible services"
means those public services that the Town has identified as requiring a higher standard of protection against flooding, including, but not limited to, hospitals, police stations and fire stations.
NNN. "Watershed"
means a basin.
OOO. "Wet pond"
means a stormwater treatment pond designed to maintain a continuous or seasonal static water level below the pond outlet elevation.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
Except as specifically provided herein, the 2005 Edition of the State of Washington, Department of Ecology's "Stormwater Management Manual for Western Washington," and all amendments and additions thereto, is adopted by this reference.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The Town of Woodway shall require the use of low impact development (LID) practices. These requirements must meet the minimum requirements of the 2005 DOE Stormwater Management Manual for Western Washington or the provisions established by this municipal code. Any deviation from the LID guidelines shall be submitted to the Town for administrative approval.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The purpose of adding LID practices to the Town of Woodway Municipal Code is to provide a mechanism to employ an alternative method of stormwater management referred to as LID. Low impact development strategies meet multiple objectives such as open space, critical area, and habitat protection while still meeting the standards and requirements set forth under the County's National Pollutant Discharge Elimination System (NPDES) permit and GMA density requirements.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
This section outlines the performance goal and objectives that govern the review of any proposed LID project.
The goal of LID is to manage stormwater generated from new development and redevelopment so there will be no negative impacts to adjacent and/or downstream property owners and no degradation to groundwater or surface waters such as but not limited to streams, ravines, wetlands, potholes, and rivers.
The LID goal shall be achieved through adherence to the following objectives:
A.
Minimize the impacts of increased stormwater runoff from new impervious surfaces and land cover conversions by maintaining peak flow frequencies and durations of the sites' predeveloped hydrologic condition (see subsection B of this section). In the Puget Sound lowlands, the predeveloped hydrologic condition is near zero overland flow runoff and this objective, in concert with other objectives, is meant to closely achieve that condition. (Note: To provide a quantifiable and measurable standard for flow control, the Minimum Requirement No. 7: Flow Control, from the 2005 DOE Stormwater Management Manual for Western Washington will be adhered to in addition to meeting the other objectives listed below. The stormwater discharge shall match developed discharge durations to predeveloped durations for the range of predeveloped discharge rates from fifty percent of the two-year peak flow up to the full fifty-year peak flow.)
B.
Establish the definition of the predeveloped condition of a site as forested. This definition establishes the hydrologic conditions, which the developed site must attempt to achieve as demonstrated by modeling and by adherence to the other objectives.
C.
Where possible, retain or restore sixty-five percent of the site's native soils and vegetation as open space within the zoning areas R-43 and R-87 and for all subdivisions. Where sixty-five percent is not achieved, the applicant will demonstrate that the maximum possible use of other LID techniques, as outlined in the standards contained in the 2005 DOE Stormwater Management Manual for Western Washington and in the 2005 Low Impact Development Technical Guidance Manual for Puget Sound prepared by the Puget Sound Action Team, have been met.
D.
Retain and incorporate natural site features that promote infiltration of stormwater on a developed site.
E.
Employ low impact development best management practices (BMPs) as outlined in the 2005 DOE Stormwater Management Manual and the 2005 Low Impact Development Technical Guidance Manual for Puget Sound prepared by the Puget Sound Action Team and minimize the use of traditional conveyance and pond technologies to manage stormwater quality and quantity.
F.
Manage stormwater as close to the origin as possible.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The Mayor or designee shall have general charge of and supervision over the administration and enforcement of this title.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
Proponents of projects types listed below shall submit a drainage and erosion control plan to the Administrator in accordance with the notes listed.
Table 1 Types of Projects for Which Drainage and Erosion Control Plans Are Required as a Condition of Project Approval | |
|---|---|
Activities or Projects Requiring Permit | (See "Notes" below) |
Preliminary plat | 1 |
Short plat | 1 |
Cluster subdivisions | 1 |
Large lot subdivisions | 5 |
Public facilities construction (e.g., roads, parks, structures, utilities) | 1,4,5 |
Private utility projects | 1,4 |
Residential building permit | 1 |
Shoreline substantial development permit | 1 |
Projects in flood hazard zone | 1,4 |
Special use permit | 1,4 |
Clearing | 2 |
Class 4 general forest practices approval | 2 |
Grading | 3 |
Projects subject to zoning site plan review | 1,4 |
Projects on bluffs | 6 |
Projects in critical areas | 1 |
Notes: | |
|---|---|
1. | A drainage and erosion control plan shall be required as a condition of a permit for projects on which five thousand square feet or more will be made impervious as a result of the project, except in critical areas, which have a zero threshold. For subdivisions, the imperviousness of lots to be developed in the future shall be included in the computation of impervious surface. In addition to the requirements of this code, the plans shall be designed in accordance with the Town's published developer guidelines. |
2. | A drainage and erosion control plan shall be required as a condition of a permit for a permit to clear one-quarter acre or greater. |
3. | A small parcel erosion and sediment control plan shall be required as a condition of a permit for all grading projects. |
4. | For redevelopment projects, the entire site will require a drainage and erosion control plan and shall be designed to conform to current drainage standards. For projects that fall below the threshold for redevelopment projects, the new work only shall be subject to this chapter, except that a source control plan shall be submitted for the entire site in accordance with Section 11.02.140. |
5. | A drainage and erosion control plan shall be required for long subdivisions that, pursuant to this code, require engineered design plans and profiles for roads. |
6. | Projects subject to bluff review in addition to the requirements of a drainage and erosion control plan shall be subject to Section 11.02.080. |
(Ord. 06-470 § 2(part), 2006; Ord. 09-506 § 1(Exh. A(part)), 2009; Ord. 17-578 § 1 (Exh. D (part)), 2017)
B.
The Administrator shall attach such conditions to the erosion and sediment control plan as are necessary to control erosion and runoff, including but not limited to:
1.
Installing French drains (drywells) or other on-site facilities for retention, detention, or disposal of runoff from roofs and other impervious surfaces; and/or
2.
Routing storm drainage as necessary and appropriate for the size of project; and/or
3.
Installing erosion control devices (such as construction entrances, filter fabric fences, stockpile protection, buffers for critical areas); and/or
4.
Easements and setbacks as required to ensure maintenance access, buffers, proper drainage, or other functions cited in the manual.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
All utilities, port, irrigation, drainage and flood control districts, railroads, cities, towns, counties, and other local, State and Federal government entities which are proponents of projects within the Town shall be subject to and comply with all of the requirements of this chapter.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The Administrator may exempt from the submittal requirements of Sections 11.02.040 and 11.02.050 the following projects:
A.
Projects that the Administrator determines are required to be performed immediately in order to safeguard and protect the life or property of any person or persons;
B.
Public works projects that are completely within the Town right-of-way and will not increase impervious surface;
C.
Projects for which the impervious area to be added or modified plus the existing impervious surfaces results in total impervious surface of less than five percent of the parcel; provided, that no runoff or sediment discharge to adjoining property or to waters of the United States is reasonably probable;
D.
Routine agricultural practices, including but not limited to plowing or harrowing;
E.
Grading of land for agricultural purposes only; provided, that the Administrator has determined that environmentally critical areas will not be significantly affected; or
F.
Grading projects for which no grading permit is required by the Town.
(Ord. 06-470 § 2(part), 2006; Ord. 09-506 § 1(Exh. A(part)), 2009; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
A bluff plan must be prepared for bluff projects to:
1.
Convey runoff from and/or over the project site away from the bluff, if possible, or safely conveyed over the bluff;
2.
Prevent sediment from leaving the project site;
3.
Protect vegetation that stabilizes the bluff;
4.
Prevent to the extent possible the infiltration of runoff so close to the bluff as to pose a threat to bluff stability.
B.
The plan shall be prepared by a licensed civil engineer per the requirements of the 2005 DOE Stormwater Management Manual for Western Washington. There is no minimum size threshold for projects on bluffs, and all bluff plans must be prepared by a licensed civil engineer. In addition, a geotechnical report shall be required if:
1.
The proposed project is seaward of a plane extending landward from the toe of the bluff on a fifty percent slope (2H:1V).
2.
Off-site drainage may cross the property to the bluff that would require engineering calculations of runoff for the build-out condition in the tributary area.
3.
The Administrator believes that development or runoff from development may destabilize the bluff or endanger property or lives.
C.
The plan must take into consideration the following items for the one-hundred-year, continuous simulation modeled developed condition design storm:
D.
Infiltration facilities shall not be allowed so close to a bluff as to pose a threat to the stability of the bluff and under no circumstances will infiltration facilities be allowed seaward of a plane extending landward from the toe of the bluff on a fifty percent slope (2H:1V).
E.
The plan shall include drawings of facilities and specifications sufficient for construction.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The plat of Woodway Highlands was built with a stormwater system that was sized for conveying stormwater based on a maximum impervious area. Each lot within the plat has a maximum allowable impervious area. Any project within the plat that proposes additional impervious area that exceeds the maximum allowable impervious area for the respective lot will not be allowed to connect to the existing stormwater conveyance system and will be subject to additional stormwater requirements as determined by the Town Engineer.
(Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
A drainage and erosion control plan shall be submitted to the Administrator concurrently with other plans required for the project, including as applicable but not limited to vegetation removal/clearing, final grading, landscaping, water and sewer, community on-site sanitary waste disposal system, roads, utilities plans and other relevant site work.
B.
A drainage and erosion control plan shall be submitted concurrently with the application for a permit or preliminary project approval.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A drainage and erosion control plan showing the overall project, clearly delineating phase boundaries and estimating dates of construction shall be part of any initial submittal. Phased projects shall be completed in accordance with approved plans and in accordance with standard phased development requirements of the Town. Thresholds used for determining drainage requirements will be applied to all phases of a project. If the combined phases of any project exceed the threshold allowance, then the pending application and previously approved phases shall be designed to meet minimum thresholds.
A project will be considered a phased project if, combined with work completed within the previous four years, the thresholds are exceeded. This includes both project applications submitted as phased projects and those individual projects that, when added together, exceed the thresholds.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A drainage and erosion control plan shall be comprised of the following:
A.
A drainage report which includes the information required in this code and Section 3.1.7 of the 2005 DOE Stormwater Management Manual for Western Washington in the format described in Section 11.02.130;
D.
An erosion and pollution control plan as described in Volume II of the 2005 DOE Stormwater Management Manual for Western Washington.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A drainage and erosion control plan shall be completed by a civil engineer with a current State of Washington professional engineer's license. All plans and specifications, calculations, construction inspection reports and all other submittals which will become part of the permanent record of the project must bear the project engineer's official seal, when more than five thousand square feet of impervious area is added to a site, and also for any project located within an environmentally critical area as identified on the Town's critical area maps.
(Ord. 06-470 § 2(part), 2006; Ord. 09-506 § 1(Exh. A(part)), 2009; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The drainage report referred to in Section 11.02.110 shall be written in accordance with the guidelines given in the 2005 DOE Stormwater Management Manual for Western Washington. The following items shall also be included:
A.
Cover Sheet. The drainage report shall have a cover sheet which identifies the name of the project, the proponent's name, address, and telephone number, the project engineer, the date of submittal, and the name, address, and telephone number of the project's contact person.
B.
Project Engineer's Certification. The drainage report shall include the following certificate:
I hereby certify that this Drainage and Erosion Control Plan for (name of project) has been prepared by me or under my supervision and meets minimum standards of the Town of Woodway and normal standards of engineering practice. I understand that the Town does not and will not assume liability for the sufficiency, suitability or performance of drainage facilities designed by me.
Said certificate shall be signed by the project engineer, and his seal shall be affixed thereto.
C.
Table of Contents. The table of contents shall indicate the number of pages in each section of the report for which the project engineer is responsible. The page numbers for appendices shall also be included in the table of contents.
D.
One-Hundred-Year Flood Analysis. If there is a natural water body such as a stream or lake on or adjacent to the project, this section of the drainage report shall show existing one-hundred-year flood limits. If none exist, the Administrator may request that the project engineer prepare a backwater analysis to determine flooding limits for the one-hundred-year flood.
E.
Aquifer Recharge Area. If the project is located within the aquifer recharge area shown on the Town of Woodway critical area overlay, the applicant shall request all available information from the Town regarding development guidelines and precautions within that area. Applicant shall comply with all Federal, State, and local agency requirements with regard to the aquifer recharge area. All plans within the aquifer recharge area shall be reviewed by the local water district.
F.
Stormwater Site Plan Appendix A – Facility Inventory Form. The drainage report shall include as Appendix A a facility inventory form for each detention/retention and treatment facility as provided by the Administrator.
G.
Stormwater Site Plan Appendix B – Bond Quantities. The drainage report shall include as Appendix B a worksheet with quantities and unit costs for the purpose of calculating the required bond amount.
H.
Stormwater Site Plan Appendix C – Property Owners' Association Articles. The drainage report shall include as Appendix C the property owners' association articles showing inclusion therein of the maintenance and source control plan and authorizing the association to raise money through dues and to maintain drainage facilities.
I.
Stormwater Site Plan Appendix D – Special Studies. The drainage report shall include as Appendix D any special studies associated with the project (i.e., soils report, wetland report, basin studies, groundwater studies, flooding studies).
J.
Stormwater Site Plan Appendix E – Inspection Schedule. The drainage report shall include as Appendix E a schedule of project inspections to be made by the project engineer. The Administrator shall require as a minimum that erosion control facilities, infiltration facilities, and treatment facilities be inspected at key points during construction to ensure that they are built according to plans and specifications and that they are being protected. Inspection shall be reported pursuant to Section 11.02.160.
(Ord. 06-470 § 2(part), 2006; Ord. 09-506 § 1(Exh. A(part)), 2009; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Property owner(s) or the property owners' association shall maintain the storm drainage facilities outside of the public right-of-way as required by this chapter. To this end, the project engineer shall prepare a maintenance and source control plan to be used by the property owners or the property owners' association. This plan shall be bound separately from the drainage report referred to in Section 11.02.130.
B.
The articles of the property owners' association shall include by reference the project's drainage and erosion control plan, including the maintenance and source control plan referred to herein, and shall include the following language:
In the event project Proponent (or successors or the property owners' association), in the judgment of the Town fails to maintain the drainage facilities installed within the plat, or if the Proponent or its successors or the property owners' association willfully or accidentally reduces the capacity of the drainage system or renders any part of the drainage system unusable, the Proponent or its successors or the property owners' association agrees to the following remedy: The Town shall mail to the Proponent or its successors or the property owners' association a written notice by first class mail and certified mail, return receipt requested, requiring the Proponent or its successors or the property owners' association to correct the problem or maintain the facilities as necessary to restore the full design capacity of the drainage system within 30 days after receipt of said notice. If the Proponent or its successors or the property owners' association fails to correct the problem or maintain the facilities as necessary to restore the full design capacity of the drainage system, then the Town may correct the problem itself and bill the Proponent or its successors or the property owners' association for all costs associated with the engineering and construction of the remedial work. The Town may charge interest as allowed by law from the date of completion of construction until the costs are paid in full. Should the Town consult with an attorney or file suit to collect the costs due from the Proponent, its successors or the property owners' association, then the proponent or its successors or the property owners' association shall pay to the Town a reasonable attorney's fee and costs.
C.
A covenant stating the property owners' or property owners' association's specific maintenance responsibilities shall be included on the face of the plat and recorded against each lot in the subdivision. The covenant shall include the following or substantially similar language:
Maintenance Covenant
Easements are hereby granted for the installation, inspection and maintenance of utilities and drainage facilities as delineated on the plat for subdivision. No encroachment which may damage or interfere with the installation, inspection and maintenance of utilities will be placed within the easements shown on the plat. The maintenance and expense of maintaining the utilities and drainage facilities shall be the responsibility of the property owners or the property owners' association as established by covenant recorded under Snohomish County Auditor's file number.
D.
The maintenance and source control plan shall:
1.
Describe the required type, location and design features (e.g., orifice plates, spillways) of drainage facilities;
2.
Define the frequency of drainage facilities maintenance, including but not limited to sediment removal, cleaning of catch basins and vegetation controls;
3.
Incorporate at least the minimum standards for inspection and maintenance then available from the Administrator;
4.
Include an estimate of the average annual cost of maintenance; and
5.
Describe hazardous materials handling protocols developed specifically for the type of development or business designed to prevent the release of pollution from the site. Incorporate the relevant procedures found in Volume IV of the 2005 DOE Stormwater Management Manual for Western Washington and attach copies as necessary.
E.
Maintenance and source control plans submitted to the Administrator for approval shall include copies of all required covenants.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The project engineer's engineering plans supporting the drainage and erosion control plan shall be sufficiently clear so as to enable construction of the project in proper sequence, using specified methods and materials, with sufficient dimensions to fulfill the intent of all Town ordinances and these design guidelines. The plans shall comply with the following:
A.
The sheets on which the drawings are placed shall be twenty-four inches by thirty-six inches.
B.
All sheets will have a north arrow, scale, bench mark reference and at least two coordinates matching the Town's coordinate system.
C.
Each set of drawings shall include a legend explaining the map symbols used. The number of sheets shall be adequate to clearly display the following:
1.
Topographic Basin-Vicinity Map. Using the most recent topographical information available, the base map shall show the project's boundaries, subbasin boundaries, off-site areas tributary to the project, contours, major drainage features such as channels, detention facilities and floodways, and flow path to receiving waters.
2.
Topographic Site Map.
a.
This topographic map shall show existing conditions and the proposed project, including but not limited to:
i.
Existing topography for the site and at least fifty feet beyond the site boundaries;
ii.
Finished grades;
iii.
Existing structures within one hundred feet of the project boundaries;
iv.
Utilities;
vi.
Environmentally critical areas, including, but not limited to, gullies, ravines, swales, wetlands, steep slopes, aquifer recharge area, estuaries, springs, wetlands, creeks and lakes, showing the direction of natural drainage flow;
vii.
Existing and proposed wells on site and on adjacent properties within one hundred feet of property, whether "of record" or not;
viii.
Existing and proposed fuel tanks;
ix.
Existing and proposed on-site sanitary systems;
x.
Proposed structures including, but not limited to, roads and parking surfaces;
xi.
Lot dimensions and areas;
xii.
Proposed drainage facilities with sufficient cross sections and details to build; and
xiii.
Standard stormwater plan notes.
b.
The contour intervals on the site map must be as follows:
Slope % | Contour Interval (feet) |
|---|---|
0 to 40 | 2 |
> 40 | 5 |
Topography must be field verified for drainage easements and conveyance systems. Contours shall extend fifty feet beyond the property lines.
c.
If required by the Administrator, the topographical site map shall show a schedule of catch basins including the following:
i.
Catch basin/manhole identifier;
ii.
Street name;
iii.
Cross street;
iv.
Stationing;
v.
Street side;
vi.
Catch basin diameter or size;
vii.
Invert in/out; and
viii.
Pipe diameter in/out.
Plans or worksheets of open channel systems shall show water surface elevation for the design storm, invert elevations at breaks in the grade, design discharge, design velocity, and such other data as may be required by the Administrator.
3.
Topographic Work Map(s). This map shall explain the project engineer's conveyance system analysis and shall be keyed to computer input. Conveyance links and contributing areas should be named or numbered consistent with that computer input. Using the same scale as the topographic site map, the contour topographical work map shall:
a.
Show unit areas used in calculations contributing to a reach of swale or to a catch basin, including off-site area;
b.
Identify areas contributing to retention/detention facilities;
c.
Show area, percent impervious, average slope and estimated ultimate infiltration rate for unit areas;
d.
Conveyance data, identifier (for reference to model output), length, slope, inverts up and down;
e.
Overland flow paths and distances;
f.
Soil types;
g.
Locations of soil pits and infiltration tests; and
h.
Spot water surface elevation discharges and velocities for the design event.
4.
Temporary erosion and sedimentation control plan drawing shall be as required per Section 3.3.2 of the 2005 DOE Stormwater Management Manual for Western Washington.
(Ord. 06-470 § 2(part), 2006; Ord. 09-506 § 1(Exh. A(part)), 2009; Ord. 17-578 § 1 (Exh. D (part)), 2017)
For projects requiring a drainage and erosion control plan, the proponent may be required to retain a licensed civil engineer to inspect or oversee inspection of parts of the project as directed by the Administrator and/or the drainage and erosion control plan (Appendix E, stormwater site plan, see Section 11.02.130(J)). These inspections shall be in addition to those performed by the Town of Woodway. Before the project is finalized, the project engineer shall file a construction inspection report, if such inspection was required, with the Administrator, on a form to be provided by the Administrator. Said report shall describe all factors relating to the construction of the system that satisfy the treatment, erosion control, detention/retention, flow control and conveyance requirements as designed. The project engineer's signed seal will be stamped on his construction inspection report.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
For a drainage and erosion control plan, the project engineer shall submit drawings of record bearing the project engineer's seal and showing all final locations and elevations, materials and changes substantially different from the design. Changes from the approved plan must be reviewed by the Town and approved by the Administrator.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
The Administrator shall review all drainage related submittals for general compliance with the specific criteria set forth in this chapter. An incomplete drainage and erosion control plan shall be returned to the proponent without being reviewed. An acceptance of the plan by the Administrator does not relieve the proponent or the project engineer from responsibility for ensuring that all facilities are safe and that calculations, plans, specifications, construction and drawings of record comply with normal engineering standards, this chapter and applicable Federal, State, and local laws and codes.
B.
Upon the Administrator's approval of a drainage and erosion control plan, the Town may issue the underlying permit (e.g., preliminary plat, building permit) with the implementation of the drainage and erosion control plan as a condition of said permit. The drainage and erosion control plan shall remain in full force and effect until expiration of the underlying permit pursuant to Section 11.02.190 or is revoked pursuant to Section 11.02.410.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
An approved drainage and erosion control plan shall expire with the expiration of approval for the permitted activity (i.e., a preliminary plat, clearing, grading or building permit). After expiration, a new drainage and erosion control plan must be submitted for approval, subject to conditions and requirements then currently applicable.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Until the Administrator approves a drainage and erosion control plan, the Town shall not:
B.
The Town shall not approve construction of footings for structures, unless erosion control devices are in place and functional.
C.
A preconstruction meeting with the Administrator is required to discuss sequencing of construction of erosion control and infiltration facilities, inspection and other relevant matters.
D.
For those projects requiring a drainage and erosion control plan, the Administrator shall not approve plats, grant certificates of occupancy, release financial securities related to drainage and erosion control or accept final construction until the following have been completed to the satisfaction of the Administrator:
1.
A drainage and erosion control plan;
4.
Special requirements have been inserted on the cover sheet of a plat, such as drywell or surface retention pond sizes for each lot where required;
5.
A general easement for access by Town staff to inspect and maintain all drainage facilities pursuant to Section 11.02.210;
6.
Requirements for property owners' association to maintain facilities;
7.
The recording with Snohomish County Auditor of covenants on lots, property owners' association articles, maintenance easements, agreements with adjacent property owners, conservation easements, and similar documents as required in the drainage and erosion control plan;
8.
Satisfaction of conditions of approval fulfilled; and
9.
The site has been permanently stabilized and restored, and unneeded, temporary erosion control measures have been removed.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
All manmade drainage facilities and conveyances and all natural channels, including swales, streams, lake shores, wetlands, potholes, estuaries, gullies and ravines shall be located within easements. Easements shall contain the natural features and the facilities plus a minimum of fifteen feet, or more as necessary, for access, and bordering and/or surrounding the feature. The easements shall allow the Town access for purposes of inspection, maintenance, flood control, water quality monitoring and other activities permitted by law.
B.
A minimum fifteen-foot wide access easement shall be provided to access drainage facilities from a public street or right-of-way. Access easements shall be surfaced with a minimum twelve-foot width of lattice block pavement, crushed rock or other approved surface sufficient to allow year-round access by equipment to the facility.
C.
Easements for conveyances shall be as follows:
Minimum Easement Widths for Conveyance Systems for Access, Inspection and Maintenance.
Conveyance Width | Easement Width |
|---|---|
Channels <30-inch wide | Channel +15-feet from top, one side |
Channels >30-inch wide | Channel +15-feet from top, both sides |
Pipes < or = 60-inch | 20-feet centered on pipe |
Pipes > 60-inch | 30-feet + pipe width, centered on pipe |
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The drainage and erosion control plan shall provide for the minimum setbacks set forth below:
Site Feature | Infiltration Facility Setback (feet) Up | Infiltration Facility Setback (feet) Down | Roof Downspout Drywells (feet) Up | Roof Downspout Drywells (feet) Down |
|---|---|---|---|---|
On-site septic system | 100 | 30 | 30 | 10 |
Water supply well | 100 | 100 | 30 | 10 |
Building foundation(2) | 100 | 20 | 50 | 10 |
Slopes over 15% | 50 | NA | 25 | NA |
Notes: | |
|---|---|
1. | For purposes of this section, "up" means the infiltration facility is up-gradient of the site feature. "Down" means the facility is down-gradient of the site feature: |
2. | The project engineer shall show calculations that ensure that the line of saturation, measured from the design storm elevation in the facility at a gradient acceptable to the Administrator, falls a minimum of one foot below the lowest floor elevation. The Administrator may adjust setbacks to buildings, up or down, based on these calculations. |
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
Runoff as a result of precipitation or surface water entering property from adjacent property must discharge at the natural, predevelopment location unless:
A.
A comprehensive drainage and erosion control plan is approved by the Town permitting otherwise; or
B.
An easement is granted by the downstream property owner for a different flow path for runoff to receiving waters or a public drainage system, and this alternate path is approved by the Administrator.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
When the proposed project discharges onto adjacent property on which no public drainage facility or no defined drainage course exists (e.g., a natural channel with a measurable annual discharge such as a Department of Natural Resources Type 5 rated stream), the proponent shall obtain an easement from the adjacent property owner(s) to establish a drainage way to connect to a defined drainage system. In the absence of such an easement, the discharge from retention/detention facilities shall be distributed along the property line in approximately the same flow pattern as existed prior to development.
B.
The Administrator may excuse the proponent from the requirements of this section under extraordinary circumstances such as when adjacent property is a wetland and not a closed basin and the Administrator determines that discharge to said wetland would not significantly alter the hydrology, degrade wetland functions and values or reduce the value of the property.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Design storm volumes for infiltration and detention system sizing shall be calculated per the methods listed in the 2005 DOE Stormwater Management Manual for Western Washington, with an appropriate factor of safety added based on percent impervious surface.
B.
If the project is located on till soils and the till layer is less than twenty feet below the ground surface, the proponent shall be required to dig through the till layer, if the Administrator deems it practical, and construct the infiltration facility in the more pervious soils below the till layer.
C.
The proponent shall provide for storage equal to the greatest of the following:
D.
The Administrator may reduce or eliminate the requirement to infiltrate runoff if the suitability of the site to infiltrate is limited according to the criteria set forth in the 2005 DOE Stormwater Management Manual for Western Washington, Section 3.3.7. Detention of stormwater instead of infiltration will be required in this case.
E.
Proponents of projects that discharge directly to Puget Sound are exempt from minimum storage, infiltration, and peak discharge flow control requirements. (Treatment of the water quality design event is still required.) Also exempt are proponents of projects that discharge to a public drainage system (i.e., pipes, ditches, etc.) that discharges directly to Puget Sound if the proponent shows to the satisfaction of the Administrator that:
1.
No flooding of public systems will occur as a result of the twenty-five-year design event under build-out conditions for the area tributary to the public system.
2.
All other users of the public system may enjoy the same exemption from storage requirements without flooding.
3.
No structural damage will occur to the outfall during the one-hundred-year design storm as computed by a continuous model simulation event.
Proponents shall not be exempted from the requirements for detention, infiltration, and discharge control unless the Administrator provides written confirmation.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Long-term infiltration rates for sizing infiltration facilities shall be determined as established in Section 3.3.6 of the 2005 DOE Stormwater Management Manual for Western Washington.
B.
A geotechnical evaluation is required for all sites with slopes greater than fifteen percent. The evaluation report shall provide the classification of slope per the definitions given in Section 16.10.600(B).
C.
For Class II landslide hazard areas, the report shall include recommendations for erosion control and proper site erosion given the steep slope condition.
D.
For critical Class III and Class IV landslide hazard areas, the report shall provide recommendations for safe buffer widths in accordance with the guidelines in Section 16.10.610.
(Ord. 06-470 § 2(part), 2006; Ord. 07-485 § 1, 2008; Ord. 17-578 § 1 (Exh. D (part)), 2017; Ord. 17-579 § 7, 2017)
A.
Except as provided in Section 11.02.290, all discharge of runoff from a disturbed area of two thousand square feet or greater of pollution-generating impervious area to surface or groundwater shall have water quality treatment, except in a critical area where there is a zero threshold for pollution-generating impervious area.
B.
The proponent shall select and design treatment systems according to the 2005 DOE Stormwater Management Manual for Western Washington.
C.
Alternative/new water quality treatment technologies not currently approved by the DOE may be approved by Town Administrator on a case-by-case basis. These technologies must be equivalent in performance to approved technologies and must meet the intent of all treatment requirements outlined in the 2005 DOE Stormwater Management Manual for Western Washington.
(Ord. 06-470 § 2(part), 2006; Ord. 09-506 § 1(Exh. A(part)), 2009; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Where practicable, runoff from clean impervious surfaces must be infiltrated through a low impact development system on the site.
B.
If infiltration is not possible on the site, then runoff may be routed to a retention/detention facility and infiltrated or discharged. This runoff does not require treatment prior to infiltration or discharge to surface water; provided, that it is not allowed to mix with other runoff that does require treatment. However, if it is mixed with other runoff that does require treatment, the treatment facility shall be sized as if all such runoff is contaminated.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
After development, off-site flows shall be infiltrated within or passed through the project site in the same volumes as occurred prior to development. If off site, pass-through flows shall be routed across the development site; they shall be separate from runoff generated on the project site. Flows shall not be routed through the project's conveyance, treatment or retention/detention systems. No storage or treatment of off-site pass-through flows is required.
B.
If the Administrator determines that separate handling of off-site flows is impractical, then off-site flows may be routed through the project's stormwater systems; provided, that those treatment, storage, and retention systems affected by the off-site flows shall be sized as if the off-site flows were generated within the project's boundaries in accordance with the 2005 DOE Stormwater Management Manual for Western Washington.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Based on the downstream analysis required by the drainage plan per Section 11.02.130, the Administrator may impose stricter discharge and/or detention standards if the discharge from the project, evaluated within the context of other existing conditions in the drainage area, is reasonably expected to result in any of the following:
B.
If the Administrator determines that greater treatment, infiltration and/or storage volumes, lower release rates, or downstream improvements are required, he shall specify project design criteria or other means necessary to relieve the downstream problems; provided, that such criteria will not violate the minimum standards established in this chapter. For purposes of this section, "other means" may include increases in downstream flow capacity and/or off-site detention and infiltration facilities, plans and financing for which are subject to the approval of the Administrator.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017; Ord. 17-579 § 8, 2017)
A.
Ponds shall have interior side slopes of three horizontal to one vertical or flatter unless the project engineer determines and the Administrator concurs that:
B.
Facilities with side slopes steeper than three horizontal to one vertical must be provided with a four-foot-high vinyl-coated chain link fence. Vegetation may be placed along the edge of the fence.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Drainage conveyance in the Town of Woodway shall be open swale, channel, or ditch having side slopes at no steeper than three feet horizontal to one foot vertical unless the Administrator determines that site conditions make open channels impractical. Swales and ditches with design velocities over five feet per second must be bioengineered or otherwise armored.
B.
Minimum storm sewer diameter in the public right-of-way shall be eight inches.
C.
Minimum storm sewer diameter on private property shall be six inches.
D.
Conveyances shall fully contain runoff from the twenty-five-year design event. However, the water surface elevation associated with runoff from the one-hundred-year design event shall be at least one foot below the lowest floor of any structure or the ground elevation of any building site.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
This chapter presents minimum standards for achieving the Town's goals. The Administrator has the authority to increase requirements to protect the public interest on the basis of reports pertaining to threatened water quality, erosion, habitat destruction, protection of uninterruptible services and endangerment to property.
B.
Alternatives to standard plans, specifications and design details found in the 2005 DOE Stormwater Management Manual for Western Washington may be accepted by the Administrator if they meet or exceed the performance of the standards set forth herein.
C.
Where requirements in this chapter are covered in any other law, ordinance, resolution, rule, or regulation, the more restrictive of the two shall govern.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Alternatives to these standards may be allowed at the discretion of the Administrator; provided, that the proponent will substantially meet flow control and water quality goals established by these standards. Compliance with 2005 DOE Stormwater Management Manual for Western Washington requirements shall occur within the project area, but may be performed as off-site mitigation in certain situations. Examples of cases in which alternative methods may be approved include, but are not limited to, the following:
1.
The Administrator determines that because special conditions and circumstances exist that are peculiar to the property, such as size, shape, topography, or location, literal interpretation of these standards would deprive the property owner of rights commonly enjoyed by other property owners similarly situated;
2.
The Administrator determines that the site is being redeveloped and certain site investigations would be destructive to existing structures;
3.
The Administrator determines that a remodel of an existing project is either so small or so configured that some requirements of the 2005 DOE Stormwater Management Manual for Western Washington cannot practically be met; or
4.
The Administrator determines that a public works or private sector project in an existing road right-of-way is not of adequate size to install preferred BMPs or the right-of-way cannot be expanded because of encroaching structures or setbacks for existing structures.
B.
All requests for alternatives must be submitted in writing to the Administrator, and must clearly state the specific section(s) of the 2005 DOE Stormwater Management Manual for Western Washington and this chapter from which a variance is requested and the reasons for said requested alternative.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The most recent editions of standard specifications and standard plans shall be the standards used for the design and construction of all drainage and erosion control facilities not explicitly described herein. In the event of a conflict between the standard specifications, standard plans, and the 2005 DOE Stormwater Management Manual for Western Washington, the 2005 DOE Manual shall prevail.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
Performance and maintenance bonds are required for all construction projects that require a clearing and grading permit or are connecting to the public storm drain system to ensure all required public and private improvements are completed prior to final construction approval. All bonds shall be governed by the requirements located in Section 16.08.170.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
When the Administrator determines that immediate action is required to remedy an erosion or drainage problem, the Town may perform the necessary construction or remedial work and bill the property owner, the property owner's association, or project proponent for all costs associated with said work.
B.
The Administrator may order the removal, correction or replacement of any improperly constructed or maintained storm drainage or erosion control system that the Administrator has previously reviewed and approved. All costs associated with said removal, correction or replacement shall be billed to the property owner, the property owners' association, or project proponent.
C.
The property owner, the property owners' association, and project proponent are jointly and severally liable for all costs, including a reasonable attorney's fee, incurred in any remedial action performed by the Town under this chapter. The Town may record a lien on the property owned by such jointly and severally liable entities for payment of costs plus reasonable attorney's fees. Interest shall accrue on costs and fees at the same rate as for real estate tax delinquencies and shall commence on the date of completion of remedial action.
D.
The Town assumes no liability for performing any action authorized under this section.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Any decision of the Administrator with respect to the enforcement of administration of this chapter and the 2005 DOE Stormwater Management Manual for Western Washington shall be final unless appealed to the Town Clerk by any person aggrieved thereby within fifteen days of the date of the decision being appealed. Said appeal must be in writing and shall briefly describe the basis of the appeal. Upon receipt of a timely written appeal, the Town Clerk shall advise the Hearing Examiner of the pendency of said appeal and request he/she set a date for considering the appeal.
B.
The Hearing Examiner shall conduct the appeal hearing in accordance with the Hearing Examiner's rules of procedure. All relevant evidence shall be received during the hearing. The Examiner's decision shall be made based on the testimony and materials submitted during the hearing. The Examiner may make a site visit. The procedural determination by the Town's responsible official shall carry substantial weight in the hearing. The Examiner shall issue written findings and conclusions within fifteen working days of concluding the hearing.
C.
Judicial review of the Examiner's decision may only be to Superior Court in conjunction with an appeal of the underlying action, in accordance with RCW 43.21C.075. Any such appeal must be brought within the time limits specified in RCW 36.70C.040.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
It shall be considered a violation of this chapter to:
1.
Cause or permit trash, rubbish, litter, vegetative matter or any form of debris directly or indirectly to enter a storm drainage system or to discard such matter on surfaces which drain to conveyance systems;
2.
Cause or permit to directly or indirectly enter a storm drainage system any pollutants including, but not limited to, sewage, septage, oils, petroleum products, ethylene glycol, paints, paint thinners, pesticides, fertilizers, soaps, detergents, washdown wastes, and materials on lists of pollutants in the following regulations as amended:
a.
Discarded Chemicals List, WAC 173-303-9903,
b.
Toxic Dangerous Waste List, WAC 173-303-101,
c.
Dangerous Waste Sources List, WAC 173-303-9904,
d.
Dangerous Waste Constituents List, WAC 173-303-9905,
e.
Dangerous Waste Mixtures List, WAC 173-303-084,
f.
Persistent Dangerous Waste List, WAC 173-303-102;
3.
Cause or permit damage to public or private storm drainage facilities;
4.
Cause or permit horses, cattle, or other domestic animals to enter drainage systems or waters of the United States;
5.
Cause or permit untreated runoff from stables, pastures, paddocks, corrals, kennels, or other animal enclosures to directly or indirectly enter into drainage systems or waters of the United States;
6.
Cause or permit grading, clearing, grubbing, filling, or any other land surface changes such as traversing in a motor vehicle to take place in such a way as to allow sediment from the property to directly or indirectly enter into a drainage system or waters of the United States;
7.
Cause or permit work that would transmit sediment from one part of a drainage system to another;
8.
Cause or permit the discharge into a drainage system or waters of the United States of materials that would cause the temperature of the receiving water to increase one degree Fahrenheit or more;
9.
Cause or permit a discharge into a drainage system or waters of the United States of a material that would cause the water quality of the receiving water to degrade below the State of Washington water quality standard for that water body;
10.
Cause or permit the placement of any obstructions, in waters of the United States, that would prohibit free fish passage under all flow conditions;
11.
Cause or permit the removal from waters of the United States, except under emergency conditions, of any naturally occurring woody debris. Emergency conditions may consist of flow blockage that, in the discretion of the Administrator, threatens life or property;
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
A.
Any person or entity that violates any of the provisions of this chapter shall be guilty of a misdemeanor punishable by a fine of one thousand dollars per offense. Each day during any portion of which any such person is in violation of this chapter is a separate offense and shall be punishable as provided in this section.
B.
When a project fails to comply with the terms of a drainage and erosion control plan imposed under this chapter, the Administrator may issue a written order immediately stopping all work except that which is necessary to bring the project into compliance with said plan. If the proponent fails to comply with such an order, the proponent shall be guilty of a misdemeanor punishable by a fine of one thousand dollars per offense. Each day during any portion of which any such person is in violation of this chapter is a separate offense and shall be punishable as provided in this section. If the person does not comply with any such order within thirty working days of its issuance, the Administrator may revoke the relevant permit or approval listed in Section 11.02.180(B).
C.
The intent of this chapter is to ameliorate private property values and protect life and property through the improvement of surface water quality and avoidance of surface water quality and quantity problems. It is not the intent of this chapter to take private property as a result of the review of public or private development plans, except through the intentional exercise of the Town's statutory powers of eminent domain pursuant to RCW Title 7 and a Town resolution of public use and necessity. Any proponent claiming a restraint of land use relating to the plan review procedures established herein shall notify the Town prior to proponent's acceptance of the underlying permit. The Town may modify its requirements to avoid a restraint of land use, or, in the event that the Town and proponent cannot reach an agreement on development plans that avoid restraint of land use, the Town will notify the Washington State Department of Ecology for any enforcement action the State may deem appropriate.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)
The Town's fee for review of storm drainage and erosion control facilities and on-site inspection of facilities during construction shall be based on the actual amount of time expended at an hourly rate as set forth in Section 3.32.010. Fees for review of small parcel stormwater plans shall be as set forth in Section 3.32.010, payable in advance. If such fees are not paid when due, the Administrator may revoke or refuse to grant the underlying permit or approval. If as a result of such action work is not completed, the Administrator may judge the incomplete work to constitute a drainage problem subject to sanctions described in Sections 11.02.380 and/or 11.02.410.
(Ord. 06-470 § 2(part), 2006; Ord. 17-578 § 1 (Exh. D (part)), 2017)