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Record No: CB 120044    Version: 1 Council Bill No: CB 120044
Type: Ordinance (Ord) Status: Passed
Current Controlling Legislative Body City Clerk
On agenda: 5/17/2021
Ordinance No: Ord 126336
Title: AN ORDINANCE relating to the Stormwater Code Update; amending Chapters 22.800, 22.801, 22.803, 22.805, and 22.807 of the Seattle Municipal Code.
Sponsors: Alex Pedersen
Supporting documents: 1. Summary and Fiscal Note, 2. Summary Ex A – Directors’ Report and Recommendation, 3. Summary Ex B – Environmentally Critical Areas : Best Available Science Review, 4. Summary Ex C - Draft Stormwater Manual (Draft Director's Rule), 5. Summary Ex D - Ecology Letter on Draft Stormwater Code and Manual, 6. Summary Ex E - Drainage System Requirements Director's Rule, 7. Central Staff Memo, 8. Presentation, 9. Signed Ordinance 126336, 10. Affidavit of Publication

CITY OF SEATTLE

ORDINANCE __________________

COUNCIL BILL __________________

title

AN ORDINANCE relating to the Stormwater Code Update; amending Chapters 22.800, 22.801, 22.803, 22.805, and 22.807 of the Seattle Municipal Code.

body

WHEREAS, The City of Seattle is committed to protecting local creeks and lakes, the Duwamish River and Puget Sound; and

WHEREAS, Seattle Public Utilities fosters healthy people, environment, and economy by partnering with the community to equitably manage water and waste resources for today and for future generations; and

WHEREAS, The City of Seattle uses stormwater regulations to protect people, property, and the environment from damage related to stormwater runoff, for the purposes stated in Section 22.800.020 of the Seattle Municipal Code; and

WHEREAS, The City of Seattle is subject to the 2019-2024 Phase I Municipal Stormwater Permit (National Pollutant Discharge Elimination System and State Waste Discharge General Permit for Discharges from Large and Medium Municipal Separate Storm Sewer Systems) issued July 1, 2019 (“MS4 Permit”), by the State of Washington Department of Ecology (“Ecology”) in compliance with the federal Clean Water Act and state law, as effective August 1, 2019; and

WHEREAS, the MS4 Permit requires the City’s Stormwater Code and associated technical manual include minimum requirements, thresholds, definitions, and other specified requirements, limitations and criteria, determined by Ecology to be equivalent to Appendix 1 of the MS4 Permit for new development, redevelopment, and construction, and that maintenance and source control must be as least as protective as or functionally equivalent to Ecology’s Stormwater Management Manual for Western Washington, 2019 edition; and

WHEREAS, the MS4 Permit also requires the City evaluate and, if necessary, revise the Stormwater Code to incorporate low impact development principles and best management practices; and

WHEREAS, this ordinance, to be known as the 2021 Stormwater Code Update, contains amendments to comply with the MS4 Permit and other amendments not required to comply with the MS4 Permit, to further the purposes of the Stormwater Code; and

WHEREAS, the City is in the final stages of securing Ecology’s approval of certain Seattle Stormwater Manual provisions that were drafted to meet MS4 Permit obligations, and the approved provisions will be adopted during 2021 by joint Directors’ Rule of Seattle Public Utilities and the Seattle Department of Construction and Inspections; and

WHEREAS, Ecology has reviewed the City’s proposed revisions to the Stormwater Code that were drafted in response to the City’s MS4 Permit obligations and that required Ecology approval, and Ecology has found that those provisions, together with final approved Seattle Stormwater Manual revisions, will meet the regulatory requirements of the MS4 Permit; and

WHEREAS, Chapter 22.800 of the Seattle Municipal Code was established, and Chapter 22.805 of the Seattle Municipal Code was added, by Ordinance 123105, which repealed and re-enacted, relocated, and amended the text of Chapters 22.800, 22.801, 22.802, and 22.808 of the Seattle Municipal Code, previously amended by Ordinances 122738, 122055, 121276, 119965, 118396, 117852, 117789, 117697, and 117432 and adopted by Ordinance 116425; and

WHEREAS, Sections 22.800.040, 22.805.050, and 22.805.060 of the Seattle Municipal Code were amended by Ordinance 124758; and

WHEREAS, Chapters 22.800, 22.801, 22.802, 22.803, 22.805, 22.807, and 22.808 of the Seattle Municipal Code were amended by Ordinance 124872; and

WHEREAS, Section 22.801.030 of the Seattle Municipal Code was amended by Ordinance 126278; and

WHEREAS, in developing stormwater regulations that protect the functions and values of critical areas, including those in the Shoreline District, the City has included the best available science; NOW THEREFORE,

BE IT ORDAINED BY THE CITY OF SEATTLE AS FOLLOWS:

Section 1. Chapter 22.800 of the Seattle Municipal Code, last amended by Ordinance 124919, is amended as follows:

Chapter 22.800 TITLE, PURPOSE, SCOPE AND AUTHORITY

* * *

22.800.040 Exemptions, Adjustments, and Exceptions

A. Exemptions

1. The following land uses are exempt from the provisions of this subtitle:

a. Commercial agriculture, including only those activities conducted on lands defined in RCW 84.34.020(2), and production of crops or livestock for wholesale trade; and

b. Forest practices regulated under Title 222 Washington Administrative Code, except for Class IV general forest practices, as defined in WAC 222-16-050, that are conversions from timber land to other uses.

2. The following land disturbing activities are not required to comply with the specific minimum requirements listed below.

a. Maintenance, repair, or installation of underground or overhead utility facilities, such as, but not limited to, pipes, conduits and vaults, and that includes replacing the ground surface with in-kind material or materials with similar runoff characteristics are not required to comply with Section 22.805.070 (Minimum Requirements for On-site Stormwater Management), Section 22.805.080 (Minimum Requirements for Flow Control), or Section 22.805.090 (Minimum Requirements for Treatment), except as modified as follows:

((1) Installation of a new or replacement of an existing public drainage system, public combined sewer, or public sanitary sewer in the public right-of-way shall comply with Section 22.805.060 (Minimum Requirements for Roadway Projects) when these activities are implemented as publicly bid capital improvement projects funded by Seattle Public Utilities; and

2)) 1) Installation of underground or overhead utility facilities that are integral with and contiguous to a road-related project shall comply with Section 22.805.060 (Minimum Requirements for Roadway Projects).

b. Pavement maintenance practices limited to the following activities are not required to comply with Section 22.805.060 (Minimum Requirements for Roadway Projects), Section 22.805.070 (Minimum Requirements for On-site Stormwater Management, Section 22.805.080 (Minimum Requirements for Flow Control), or Section 22.805.090 (Minimum Requirements for Treatment):

1) Pothole and square cut patching;

2) Overlaying existing asphalt or concrete or brick pavement with asphalt or concrete without expanding the area of coverage;

3) Shoulder grading;

4) Reshaping or regrading drainage ditches;

5) Crack sealing; and

6) Vegetation maintenance.

c. Land disturbing activity that includes replacing the ground surface with in-kind material or with materials having equivalent runoff characteristics and is associated solely with soil remediation or tank removal for the purpose of removing contaminants and pollutants and not associated with other development is not required to comply with subsections 22.805.050.A and 22.805.060.A (Soil Amendment), Section 22.805.070 (Minimum Requirements for On-site Stormwater Management), or Section 22.805.080 (Minimum Requirements for Flow Control). Projects that include any development in addition to soil remediation or tank removal replaced with in-kind material or with materials having equivalent runoff characteristics are not exempt.

d. Drainage control facilities that are part of a public retrofit project installed to meet Appendix 12 to the City’s municipal stormwater NPDES permit or for combined sewer control, or other voluntary retrofit project, are not required to comply with Section 22.805.070 (Minimum Requirements for On-site Stormwater Management), Section 22.805.080 (Minimum Requirements for Flow Control), or Section 22.805.090 (Minimum Requirements for Treatment). This exemption does not include land disturbing activities or hard surfaces that are not integral to or are in addition to the drainage control facilities described above, or installation of drainage control facilities that are otherwise required to meet this subtitle.

3. Sites that produce no runoff as determined by a licensed civil engineer using a continuous runoff model approved by the Director are not required to comply with Section 22.805.080 (Minimum Requirements for Flow Control).

4. When a portion of the site being developed discharges only to the public combined sewer, and that portion is not required to ((comply with the provision of subsection 22.805.020.I (Install Source Control BMPs) unless)) implement source controls pursuant to Section 22.803.040 for specified activities, the Director has the authority, to the extent allowed by law, to issue an order under Chapter 22.808 requiring the responsible party to undertake source controls, if the Director determines that these activities pose a hazard to public health, safety or welfare; endanger any property; adversely affect the safety and operation of ((city)) City right-of-way, utilities, or other property owned or maintained by the City; or adversely affect the functions and values of an environmentally critical area or buffer.

5. Residential activities are not required to comply with the provision of subsection 22.805.020.I (Install Source Control BMPs) unless the Director determines that these activities pose a hazard to public health, safety or welfare; endanger any property; adversely affect the safety and operation of ((city)) City right-of-way, utilities, or other property owned or maintained by the City; or adversely affect the functions and values of an environmentally critical area or buffer.

6. With respect to all state highway right-of-way under Washington State Department of Transportation (WSDOT) control within the jurisdiction of ((the)) The City of Seattle, WSDOT shall use the current, approved Highway Runoff Manual (HRM) for its existing and new facilities and rights-of-way, as addressed in WAC 173-270-030(1) and (2). Exceptions to this exemption, where more stringent stormwater management requirements apply, are addressed in WAC 173-270-030(3)(b) and (c).

a. When a state highway is located in the jurisdiction of a local government that is required by Ecology to use more stringent standards to protect the quality of receiving waters, WSDOT shall comply with the same standards to promote uniform stormwater management.

b. WSDOT shall comply with standards identified in watershed action plans for WSDOT rights-of-way, to the extent required by state law.

c. Other instances where more stringent local stormwater standards apply are projects subject to tribal government standards or to the stormwater management-related permit conditions imposed under Chapter 25.09 to protect environmentally critical areas and their buffers (under the Growth Management Act), an NPDES permit, or shoreline master programs (under the Shoreline Management Act). In addition, WSDOT shall comply with local jurisdiction stormwater standards when WSDOT elects, and is granted permission, to discharge stormwater runoff into a municipality’s drainage system or combined sewer system.

B. Adjustments

1. The Director may approve a request for adjustments to the requirements of this subtitle when the Director finds that:

a. The adjustment provides substantially equivalent environmental protection; and

b. The objectives of safety, function, environmental protection, and facility maintenance are met, based on sound engineering practices.

2. During construction, the Director may require, or the applicant may request, that the construction of drainage control facilities and associated project designs be adjusted if physical conditions are discovered on the site that are inconsistent with the assumptions upon which the approval was based, including but not limited to unexpected soil and/or water conditions, weather generated problems, or changes in the design of the improved areas.

3. A request by the applicant for adjustments shall be submitted to the Director for approval prior to implementation. The request shall be in writing and shall provide facts substantiating the requirements of subsection 22.800.040.B.1 and, if made during construction, the factors in subsection 22.800.040.B.2. Any such modifications made during the construction of drainage control facilities shall be recorded on the final approved drainage control plan, a revised copy of which shall be filed by the Director.

C. Exceptions

1. The Director may approve a request for an exception to the requirements of this subtitle when the applicant demonstrates that the exception will not increase risks in the vicinity and/or downstream of the property to public health, safety and welfare, or to water quality, or to public and private property, and:

a. The requirement would cause a severe and unexpected financial hardship that outweighs the requirement’s benefits, and the criteria for an adjustment cannot be met; or

b. The requirement would cause harm or a significant threat of harm to public health, safety and welfare, the environment, or public and private property, and the criteria for an adjustment cannot be met; or

c. The requirement is not technically feasible, and the criteria for an adjustment cannot be met; or

d. An emergency situation exists that necessitates approval of the exception.

2. An exception shall only be granted to the extent necessary to provide relief from the economic hardship, to alleviate the harm or threat of harm, to the degree that compliance with the requirement becomes technically feasible, or to perform the emergency work that the Director determines exists.

3. An applicant is not entitled to an exception, whether or not the criteria allowing approval of an exception are met.

4. The Director may require an applicant to provide additional information at the applicant’s expense, including, but not limited to, an engineer’s report or analysis.

5. When an exception is granted, the Director may impose new or additional requirements to offset or mitigate harm that may be caused by granting the exception, or that would have been prevented if the exception had not been granted.

6. Public notice of an application for an exception and of the Director’s decision on the application shall be provided in the manner prescribed for Type II land use decisions, as set forth in Chapter 23.76.

7. The Director’s decision shall be in writing with written findings of fact. Decisions approving an exception based on severe and unexpected economic hardship shall address all the factors in subsection 22.800.040.C.8.

8. An application for an exception on the grounds of severe and unexpected financial hardship must describe, at a minimum, all of the following:

a. The current, pre-project use of the site; and

b. How application of the requirement(s) for which an exception is being requested restricts the proposed use of the site compared to the restrictions that existed prior to the adoption of this current subtitle; and

c. The possible remaining uses of the site if the exception were not granted; and

d. The uses of the site that would have been allowed prior to the adoption of this subtitle; and

e. A comparison of the estimated amount and percentage of value loss as a result of the requirements versus the estimated amount and percentage of value loss as a result of requirements that existed prior to adoption of the requirements of this subtitle; and

f. The feasibility of the owner or developer to alter the project to apply the requirements of this subtitle.

9. In addition to rights under Chapter 3.02, any person aggrieved by a Director’s decision on an application for an exception may appeal to the Hearing Examiner’s Office by filing an appeal, with the applicable filing fee, as set forth in Section 23.76.022. However, appeals of a Notice of Violation, Director’s order, or invoice issued pursuant to this subtitle shall follow the required procedure established in Chapter 22.808.

10. The Hearing Examiner shall affirm the Director’s determination on the exception unless the examiner finds the determination is clearly erroneous based on substantial evidence. The applicant for the exception shall have the burden of proof on all issues related to justifying the exception.

11. The Director shall keep a record, including the Director’s written findings of fact, on all approved requests for exceptions.

* * *

22.800.070 Minimum Requirements for City Agency Projects

A. Compliance. City agencies shall comply with all the requirements of this subtitle except as specified below:

1. City agencies are not required to obtain permits and approvals under this subtitle, other than inspections as set out in subsection B of this Section 22.800.070 and review and approval when applying roadway project infeasibility as provided in subsection 22.805.060.E, for work performed within a public right-of-way or for work performed for the operation and maintenance of park lands under the control or jurisdiction of the Department of Parks and Recreation. Where the work occurs in a public right-of-way, it shall also comply with Title 15, Street and Sidewalk Use, including the applicable requirements to obtain permits or approvals.

2. A City agency project, as defined in Section 22.801.170, that is not required to obtain permit(s) and approval(s) pursuant to subsection 22.800.070.A.1 and meets all of the conditions set forth below, is not required to comply with the amendments to 22.800.020 through 22.808.110 that take effect on ((January 1, 2016)) July 1, 2021, except the amendments to this subsection 22.800.070.A.2.

a. The project begins land disturbing activities within ((18 months)) five years of the effective date of this subtitle, and;

b. The project complies with the Stormwater Code that was made effective ((November 30, 2009)) January 1, 2016, by Ordinance ((123105)) 124872 which requires compliance with Directors’ Rules ((15-2012/DWW 201.1 and 16-2012/DWW 201.2)) SDCI 17-2017/SPU DWW 200 effective ((March 1, 2013, as amended by Ordinance 124758)) January 1, 2016; and

c. The project meets one or more of the following criteria:

1) Project funding was appropriated as identified in Ordinance ((124648)) 126237 titled, “An ordinance adopting a budget, including a capital improvement program and position modifications, for the City of Seattle for ((2015)) 2021”; or

2) Project received or will receive voter approval of financing before ((January 1, 2015)) January 1, 2021; or

3) Project received or will receive funds based on grant application(s) submitted before ((January 1, 2015)) January 1, 2021.

B. Inspection

1. When the City conducts projects for which review and approval are required under Chapter 22.807 (Drainage Control Review and Application Requirements) the work shall be inspected by the City agency conducting the project or supervising the contract for the project. The inspector for the City agency shall be responsible for ascertaining that the drainage control is done in a manner consistent with the requirements of this subtitle.

2. A City agency need not provide an inspector from its own agency provided either:

a. The work is inspected by an appropriate inspector from another City agency; or

b. The work is inspected by an appropriate inspector hired for that purpose by a City agency; or

c. The work is inspected by the licensed civil or geotechnical engineer who prepared the plans and specifications for the work; or

d. A permit or approval is obtained from the Director of SDCI, and the work is inspected by the Director.

C. Certification of Compliance. City agencies shall meet the same standards as non-City projects, except as provided in subsection 22.800.070.A, and shall certify that each individual project meets those standards.

* * *

22.800.080 Authority

A. For projects not conducted in the public right-of-way, the Director of SDCI has authority regarding the provisions of this subtitle pertaining to grading, review of drainage control plans, and review of construction stormwater control plans, and has inspection and enforcement authority pertaining to temporary erosion and sediment control measures.

B. The Director of SPU has authority regarding all other provisions of this subtitle pertaining to drainage water, drainage, and erosion control, including inspection and enforcement authority. The Director of SPU may delegate authority to the Director of SDCI or the Director of SDOT regarding the provisions of this subtitle pertaining to review of drainage control plans, inspection of drainage control facilities, review of construction stormwater control plans, and inspection and enforcement authority pertaining to temporary erosion and sediment control measures for projects conducted in the public right-of-way.

C. The Directors of SDCI, SDOT, and SPU are authorized to take actions necessary to implement the provisions and purposes of this Subtitle VIII in their respective spheres of authority to the extent allowed by law, including, but not limited to, the following: promulgating and amending rules and regulations, pursuant to the Administrative Code, Chapter 3.02; establishing and conducting inspection programs; establishing and conducting or, as set forth in Section 22.802.040, requiring responsible parties to conduct monitoring programs, which may include sampling of discharges to or from drainage control facilities, the public drainage system, or receiving waters; taking enforcement action; abating nuisances; promulgating guidance and policy documents; and reviewing and approving, conditioning, or disapproving required submittals and applications for approvals and permits. The Directors are authorized to exercise their authority under this Subtitle VIII in a manner consistent with their legal obligations as determined by the courts or by statute.

D. The Director of SPU is authorized to develop, review, or approve drainage basin plans for managing receiving waters, drainage water, and erosion within individual basins. A drainage basin plan may, when approved by the Director of SPU, be used to modify requirements of this subtitle, provided the level of protection for human health, safety and welfare, the environment, and public or private property will equal or exceed that which would otherwise be achieved. A drainage basin plan that modifies the minimum requirements of this subtitle at a drainage basin level subject to the municipal stormwater NPDES Permit must be reviewed and approved by Ecology and adopted by City ordinance.

E. The Director of SPU is authorized, to the extent allowed by law, to develop, review, or approve an Integrated Drainage Plan as an equivalent means of complying with the requirements of this subtitle, in which the developer of a project voluntarily enters into an agreement with the Director of SPU to implement an Integrated Drainage Plan that is specific to one or more sites where best management practices are employed such that the cumulative effect on the discharge from the site(s) to the same receiving water is the same or better than that which would be achieved by a less integrated, site-by-site implementation of best management practices.

F. ((The)) For projects that do not discharge to the combined sewer system, the Director of SPU is authorized, to the extent allowed by law, to enter into an agreement with the developer ((of a project for the developer)) to allow a project’s flow control, water quality treatment, on-site stormwater management, or wetland protection requirements to be met at an alternative location if the following conditions are met, or if another scenario is approved by Ecology:

1. The developer enters the agreement voluntarily to contribute funds toward the construction of, or to construct, one or more drainage control facilities ((that)) at an alternative location to mitigate the impacts to the same receiving water that have been identified as a consequence of the ((proposed development.)) project; and

2. The alternative location is for an equivalent area in terms of flow and pollution characteristics when compared with the project, as determined by the Director; and

a. The site of the project has greater than or equal to 35 percent existing hard surface coverage and the project discharges to:

1) A Listed Creek and the equivalent area is in-basin, which means that the equivalent area is on the same site as the project, the project is located within contributing area to the equivalent area, or the equivalent area discharges from the public drainage system to the receiving water at the same point as (or upstream of) the point where the project area discharges from the public drainage system to the same receiving water; or

2) A receiving water other than a Listed Creek and the equivalent area discharges to the same receiving water as the project.

G. ((The)) For projects that discharge to the combined sewer system, the Director of SPU is authorized, to the extent allowed by law, to enter into an agreement with the developer ((of a project for the developer)) to allow a project’s flow control or on-site stormwater management requirements to be met at an alternative location if the developer enters the agreement voluntarily to contribute funds towards the construction of, or to construct, one or more drainage control facilities at an alternative location, determined by the Director, to mitigate the impacts ((to the same receiving water)) that have been identified as a consequence of the ((proposed development)) project.

H. If the Director of SPU determines that a discharge from a site, real property, or drainage control facility, directly or indirectly to a public drainage system, a private drainage system, or a receiving water within or contiguous to Seattle city limits, has exceeded, exceeds, or will exceed water quality standards at the point of assessment, or has caused or contributed, is causing or contributing, or will cause or contribute, to a prohibited discharge or a known or likely violation of water quality standards in the receiving water or a known or likely violation of the City’s municipal stormwater NPDES permit, and cannot be adequately addressed by the required best management practices, then the Director of SPU has the authority, to the extent allowed by law, to issue an order under Chapter 22.808 requiring the responsible party to undertake more stringent or additional best management practices. These best management practices may include additional source control or structural best management practices or other actions necessary to cease the exceedance, the prohibited discharge, or causing or contributing to the known or likely violation of water quality standards in the receiving water or the known or likely violation of the City’s municipal stormwater NPDES permit. Structural best management practices may include but shall not be limited to: drainage control facilities, structural source controls, treatment facilities, constructed facilities such as enclosures, covering and/or berming of container storage areas, and revised drainage systems. For existing discharges as opposed to new projects, the Director may allow 12 months to install a new flow control facility, structural source control, or treatment facility after the Director notifies the responsible party in writing of the Director’s determination pursuant to this subsection 22.800.080.H and of the flow control facility, structural source control, or treatment facility that must be installed.

I. Unless an adjustment pursuant to subsection 22.800.040.B or an exception pursuant to subsection 22.800.040.C is approved by the Director, an owner or occupant who is required to connect, or who chooses to connect, to a public drainage system shall be required to extend the public drainage system if a public drainage system is not accessible within an abutting public area across the full frontage of the site.

J. The Director of SDCI or the Director of SPU has the authority, to the extent allowed by law, to require ((sites)) projects with any addition or replacement ((of less than 5,000 square feet)) of hard surface or ((with less than one acre of)) land disturbing activity to comply with the more stringent requirements set forth in ((Section 22.805.080 or Section 22.805.090)) Chapter 22.805 when necessary to accomplish the purposes of this subtitle. In making this determination, the Director of SDCI or the Director of SPU may consider, but is not limited to, the following attributes of the site: location within an Environmentally Critical Area; proximity and tributary to an Environmentally Critical Area; and proximity and tributary to an area with known erosion or flooding problems.

* * *

22.800.100 Transition to Revised Stormwater Code

A. Any building or grading permit issued prior to June 30, 2020, (((a))) (1) which was not considered, either in the initial application process or in a renewal process, under the version of the Stormwater Code in effect on or after January 1, 2016, and (((b))) (2) pursuant to which construction has not started by June 30, 2020, shall expire on June 30, 2020.

B. Any building or grading permit (1) which was considered under a version of the Stormwater Code in effect on or after January 1, 2016, but before July 1, 2021, and (2) pursuant to which construction has not started by July 1, 2026, shall expire on July 1, 2026.

((B)) C. Any master use permit issued prior to June 30, 2020, for a project not requiring a building permit (((a))) (1) which was not considered, either in the initial application process or in a renewal process, under the version of the Stormwater Code in effect on or after January 1, 2016, and (((b))) (2) pursuant to which construction has not started by June 30, 2020, shall expire on June 30, 2020.

D. Any master use permit for a project not requiring a building permit (1) which was considered under a version of the Stormwater Code in effect on or after January 1, 2016, but before July 1, 2021, and (2) pursuant to which construction has not started by July 1, 2026, shall expire on July 1, 2026.

((C)) E. Neither Section 23.22.028, Section 23.22.064, Section 23.24.050, RCW 58.17.033, nor RCW 58.17.170 shall require any permit application submitted on or after January 1, 2016, to be considered under a version of the Stormwater Code in effect prior to January 1, 2016, or require any permit application submitted on or after July 1, 2021 to be considered under a version of the Stormwater Code in effect prior to July 1, 2021. For purposes of this subsection ((22.800.100.C)) 22.800.100.E, “permit application” means an application for any permit required for construction within a plat or short plat or for construction of facilities and improvements for a plat or short plat, including, but not limited to, master use, building and grading permits.

((D)) F. Neither Section 23.22.028 nor Section 23.22.064 shall authorize starting construction, after June 30, 2020, of facilities or improvements for any plat without compliance with the version of the Stormwater Code in effect on or after January 1, 2016, or authorize starting construction, after July 1, 2026, of facilities or improvements for any plat without compliance with the version of the Stormwater Code in effect on or after July 1, 2021.

((E)) G. For purposes of this section, “starting construction” or “started construction” means the site work associated with and directly related to the approved project has begun. For example: grading the project site to final grade or utility installation such as water, sewer, drainage, gas, or electrical infrastructure installed to serve the project and associated with the application. Simply clearing the project site or installing conduit does not constitute the start of construction.

Section 2. Chapter 22.801 of the Seattle Municipal Code, last amended by Ordinance 126278, is amended as follows:

Chapter 22.801 DEFINITIONS

* * *

22.801.020 “A”

“Agency” means any governmental entity or its subdivision.

“Agency, City” means “City agency” as defined in Section 25.09.520.

“Approved” means approved by the Director.

“Aquatic life use” means “aquatic life use” as defined in WAC 173-201A-200. For the purposes of this subtitle, at minimum the following water bodies are designated for aquatic life use: small lakes, creeks, and ((freshwater)) fresh designated receiving waters.

“Arterial” means “arterial” as defined in Section 11.14.035.

22.801.030 “B”

“Basic treatment facility” means a drainage control facility designed to reduce concentrations of total suspended solids in drainage water.

“Basic treatment receiving water” means:

1. All marine waters, including Puget Sound;

2. Lake Union;

3. Lake Washington;

4. Ship Canal and bays between Lake Washington and Puget Sound; and

5. Duwamish River.

“Best management practice” (BMP) means a schedule of activities, prohibitions of practices, operational and maintenance procedures, structural facilities, or managerial practice or device that, when used singly or in combination, prevents, reduces, or treats contamination of drainage water, prevents or reduces soil erosion, or prevents or reduces other adverse effects of drainage water. When the Directors develop rules and/or manuals prescribing BMPs for particular purposes, whether or not those rules and/or manuals are adopted by ordinance, BMPs ((prescribed)) specified in the rules and/or manuals shall be the BMPs required for compliance with this subtitle.

“Building permit” means a document issued by the Seattle Department of Construction and Inspections authorizing construction or other specified activity in accordance with the Seattle Building Code or the Seattle Residential Code.

22.801.040 “C”

“Capacity-constrained system” means a drainage system or public combined sewer that the Director of SPU has determined to have inadequate capacity to carry existing and anticipated loads, or a drainage system that includes ditches or culverts.

“Certified Erosion and Sediment Control Lead” (CESCL) means an individual who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology.

“Civil engineer, licensed” means a person who is licensed by the State of Washington to practice civil engineering.

“City agency” means “City agency” as defined in Section 25.09.520.

“Combined sewer.” See “public combined sewer.”

“Combined sewer basin” or “public combined sewer basin” means the area tributary to a public combined sewer feature, including, but not limited to, a combined sewer overflow outfall, trunk line connection, pump station, or regulator.

“Compaction” means the densification, settlement, or packing of earth material or fill in such a way that permeability is reduced by mechanical means.

“Construction Stormwater Control Plan” means a document that explains and illustrates the measures to be taken on the construction site to ((control)) prevent erosion and discharge of sediment and other pollutants on a construction project.

“Containment area” means the area designated for conducting pollution-generating activities for the purposes of implementing source controls or designing and installing source controls or treatment facilities.

“Contaminate” means the addition of sediment, any other pollutant or waste, or any illicit or prohibited discharge.

“Creek” means a ((Type 2-5)) Type S, F, Np or Ns water as defined in WAC 222-16-031, or as defined in WAC 222-16-030 after state water type maps are adopted, and is used synonymously with “stream.”

22.801.050 “D”

“Damages” means monetary compensation for harm, loss, costs, or expenses incurred by the City, including, but not limited, to the following: costs of abating or correcting violations of this subtitle; fines or penalties the City incurs as a result of a violation of this subtitle; and costs to repair or clean the public drainage system or public combined sewer as a result of a violation. For the purposes of this subtitle, damages do not include compensation to any person other than the City.

“Designated receiving waters” means the Duwamish River, Puget Sound, Lake Washington, Lake Union, Elliott Bay, Portage Bay, Union Bay, the Lake Washington Ship Canal, and other receiving waters determined by the Director of SPU and approved by Ecology as having sufficient capacity to receive discharges of drainage water such that a site discharging to the designated receiving water is not required to implement flow control.

“Detention” means temporary storage of drainage water for the purpose of controlling the drainage discharge rate.

“Development” means the following activities:

1. Class IV-general forest practices that are conversions from timberland to other uses;

2. land disturbing activity; ((or))

3. the addition or replacement of hard surfaces;

4. expansion of a building footprint or addition or replacement of a structure;

5. structural development, including construction, installation, or expansion of a building or other structure;

6. seeking approval of a building permit, other construction permit, grading permit, or master use permit that involves any of the foregoing activities; and

7. seeking approval of subdivision, short plat, unit lot subdivision, or binding site plans, as defined and applied in chapter 58.17 RCW, or other master use permit.

Development is a type of project.

“Director” means the Director of the Department authorized to take a particular action, and the Director’s designees, who may be employees of that department or another City department.

“Director of SDCI” means the Director of the Seattle Department of Construction and Inspections or the designee of the Director of the Seattle Department of Construction and Inspections, who may be employees of that department or another City department.

“Director of SDOT” means the Director of Seattle Department of Transportation of The City of Seattle or the designee of the Director of Seattle Department of Transportation, who may be employees of that department or another City department.

“Director of SPU” means the ((Director)) General Manager and Chief Executive Officer of Seattle Public Utilities of The City of Seattle or the designee of the ((Director)) General Manager and Chief Executive Officer of Seattle Public Utilities, who may be employees of that department or another City department.

“Discharge point” means the location from which drainage water from a site is released.

“Discharge rate” means the rate at which drainage water is released from a site. The discharge rate is expressed as volume per unit of time, such as cubic feet per second.

“Drainage basin” means the geographic and hydrologic tributary area or subunit of a watershed through which drainage water is collected, regulated, transported, and discharged to receiving waters.

“Drainage basin plan” means a plan to manage the quality and quantity of drainage water in a watershed or a drainage basin, including watershed action plans.

“Drainage control” means the management of drainage water. Drainage control is accomplished through one or more of the following: collecting, conveying, and discharging drainage water; controlling the discharge rate from a site; controlling the flow duration from a site; controlling the quantity from a site; and separating, treating or preventing the introduction of pollutants.

“Drainage control facility” means any facility, including best management practices, installed or constructed for the purpose of controlling the discharge rate, flow duration, quantity, and/or quality of drainage water.

“Drainage control plan” means a plan for collecting, controlling, transporting and disposing of drainage water falling upon, entering, flowing within, and exiting the site, including designs for drainage control facilities.

“Drainage system” means a system intended to collect, convey and control release of only drainage water. The system may be either publicly or privately owned or operated, and the system may serve public or private property. It includes components such as pipes, ditches, culverts, curbs, gutters, and drainage control facilities. Drainage systems are not receiving waters.

“Drainage water” means stormwater and all other discharges that are permissible pursuant to subsection 22.802.030.A.

22.801.060 “E”

“Earth material” means any rock, gravel, natural soil, fill, or re-sedimented soil, or any combination thereof, but does not include any solid waste as defined by RCW 70.95.

“Ecology” means the Washington State Department of Ecology.

“Effective ((impervious)) hard surface” means those ((impervious)) hard surfaces that are connected via sheet flow or discrete conveyance to a drainage system.

“Enhanced treatment facility” means a drainage control facility designed to reduce concentrations of dissolved metals in drainage water.

“Environmentally critical area” (ECA) means an area designated in Section ((25.09.020)) 25.09.012.

“EPA” means the United States Environmental Protection Agency.

“Erodible or leachable materials” means wastes, chemicals, or other substances which, when exposed to rainfall, measurably alter the physical or chemical characteristics of the drainage water. Examples include: erodible soils that are stockpiled; leachable materials that are stockpiled; uncovered process wastes; manure; fertilizers; oily substances; ashes, kiln dust; and garbage dumpster leakage.

“Erosion” means the wearing away of the ground surface as a result of mass wasting or of the movement of wind, water, ice, or other geological agents, including such processes as gravitational creep. Erosion also means the detachment and movement of soil or rock fragments by water, wind, ice, or gravity.

“Excavation” means the mechanical removal of earth material.

“Exception” means relief from a requirement of this subtitle to a specific project.

“Existing grade” means “existing grade” as defined in Section 22.170.050.

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22.801.130 “L”

“Land disturbing activity” means any activity that results in a change in the existing soil cover, both vegetative and nonvegetative, or the existing topography. Land disturbing activities include, but are not limited to, clearing, grading, filling, excavation, or addition of new or the replacement of hard surface. Compaction, excluding hot asphalt mix, that is associated with stabilization of structures and road construction is also considered a land disturbing activity. Vegetation maintenance practices, including landscape maintenance and gardening, are not considered land disturbing activities. Stormwater facility maintenance is not considered land disturbing activity if conducted according to established standards and procedures.

“Large project” means a project including:

1. ((5,000)) Five thousand square feet or more of new plus replaced hard surface;

2. ((one)) One acre or more of land disturbing activity;

3. ((conversion)) Conversion of 3/4 acres or more of vegetation to lawn or landscaped area; or

4. ((conversion)) Conversion of 2.5 acres or more of native vegetation to pasture.

“Listed creeks” means Blue Ridge Creek, Broadview Creek, Discovery Park Creek, Durham Creek, Frink Creek, Golden Gardens Creek, Kiwanis Ravine/Wolfe Creek, Licton Springs Creek, Madrona Park Creek, Mee-Kwa-Mooks Creek, Mount Baker Park Creek, Puget Creek, Riverview Creek, Schmitz Creek, Taylor Creek, and Washington Park Creek.

22.801.140 “M”

“Master use permit” means a ((document issued by SDCI giving permission for development or use of land or street right-of-way in accordance with Chapter 23.76)) “master use permit” as defined in subsection 23.84A.025.

“Maximum extent feasible” means the requirement is to be fully implemented, constrained only by the physical limitations of the site, practical considerations of engineering design, and reasonable considerations of financial costs.

“Municipal stormwater NPDES permit” means the permit issued to the City under the federal Clean Water Act for public drainage systems within the City limits.

22.801.150 “N”

“Native vegetation” means “native vegetation” as defined in Section 25.09.520.

“New hard surface” means a surface that is: changed from a pervious surface to a hard surface (e.g., converting lawn to permeable pavement, resurfacing by upgrading from dirt to gravel, a bituminous surface treatment (“chip seal”), asphalt, concrete, or a hard surface structure); or upgraded from gravel to chip seal, asphalt, concrete, or a hard surface structure; or from a hard surface to a hard surface structure. Note that if asphalt or concrete has been overlaid by a chip seal, the existing condition should be considered as asphalt or concrete.

“New impervious surface” means a surface that is: changed from a pervious surface to an impervious surface (e.g., resurfacing by upgrading from dirt to gravel, a bituminous surface treatment (“chip seal”), asphalt, concrete or an impervious structure); or upgraded from gravel to chip seal, asphalt, concrete, or an impervious structure; or from a impervious surface to an impervious structure. Note that if asphalt or concrete has been overlaid by a chip seal, the existing condition should be considered as asphalt or concrete.

“Non-listed creeks” means any creek not identified in the definition of “Listed creeks” in Section 22.801.130.

“NPDES” means National Pollutant Discharge Elimination System, the national program for controlling discharges under the federal Clean Water Act.

“NPDES permit” means an authorization, license or equivalent control document issued by the EPA or Ecology to implement the requirements of the NPDES program.

“Nutrient-critical receiving water” means a surface water or water segment that is determined to be impaired due to phosphorus contributed by stormwater, as ((prescribed)) specified in rules promulgated by the Director of SPU which shall be based on consideration of waterbodies reported by Ecology, and approved by EPA, under Category 5 (impaired) under Section 303(d) of the Clean Water Act for total phosphorus through Ecology’s Water Quality Assessment.

* * *

22.801.170 “P”

“Parcel-based project” means any project that is not a roadway project, single-family residential project, sidewalk project, or trail project. The boundary of the public right-of-way shall form the boundary between the parcel and roadway portions of a project.

“Person” means an individual, receiver, administrator, executor, assignee, trustee in bankruptcy, trust estate, firm, partnership, joint venture, club, company, joint stock company, business trust, municipal corporation, the State of Washington, political subdivision or agency of the State of Washington, public authority or other public body, corporation, limited liability company, association, society or any group of individuals acting as a unit, whether mutual, cooperative, fraternal, nonprofit or otherwise, and the United States or any instrumentality thereof.

“Pervious surface” means a surface that is not impervious. See also ((,)) “impervious surface.” ((.))

“Phosphorus treatment facility” means a drainage control facility designed to reduce concentrations of phosphorus in drainage water.

“Plan” means a graphic or schematic representation, with accompanying notes, schedules, specifications and other related documents, or a document consisting of checklists, steps, actions, schedules, or other contents that has been prepared pursuant to this subtitle, such as a site plan, drainage control plan, construction stormwater control plan, stormwater pollution prevention plan, or integrated drainage plan.

“Pollution-generating activity” means any activity that is regulated by the joint ((SPU/DPD)) SPU/SDCI Directors’ Rule titled “Seattle Stormwater Manual” at “Volume 4 - Source Control” or any activity with similar impacts on drainage water. These activities include, but are not limited to: cleaning and washing activities; transfer of liquid or solid material; production and application activities; dust, soil, and sediment control; commercial animal care and handling; log sorting and handling; boat building, mooring, maintenance, and repair; logging and tree removal; mining and quarrying of sand, gravel, rock, peat, clay, and other materials; cleaning and maintenance of swimming pool and spas; deicing and anti-icing operations for airports and streets; maintenance and management of roof and building drains at manufacturing and commercial buildings; maintenance and operation of railroad yards; maintenance of public and utility corridors and facilities; and maintenance of roadside ditches.

“Pollution-generating hard surface” means those hard surfaces considered to be a significant source of pollutants in drainage water. See definition of pollution-generating impervious surface in this Section 22.801.170 for surfaces that are considered significant sources of pollutants in drainage water. In addition, permeable pavement subject to vehicular use or other pollutants as described in the definition for pollution-generating impervious surfaces is a pollution-generating hard surface.

“Pollution-generating impervious surface” means those impervious surfaces considered to be a significant source of pollutants in drainage water. Such surfaces include those that are subject to any of the following: vehicular use; ((certain)) industrial activities; ((or)) storage of erodible or leachable materials, wastes, or chemicals, and ((which)) that receive direct rainfall or the run-on or blow-in of rainfall. ((;)) Such surfaces also include roofs subject to venting of significant sources of pollutants ((;)) and metal roofs unless coated with an inert, non-leachable 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 road shoulders; bike lanes within the traveled lane of a roadway; driveways; parking lots; unfenced fire lanes; vehicular equipment storage yards; rail lines and railways; and airport runways.

The following are not considered regularly ((-)) used by motor vehicles: sidewalks and trails not subject to drainage from roads for motor vehicles; paved bicycle pathways separated from and not subject to drainage from roads for motor vehicles; fenced fire lanes; and infrequently used maintenance access roads with recurring routine vehicle use of no more than once per day.

“Pollution-generating pervious surface” means any ((non-impervious)) pervious surface subject to any of the following: vehicular use; ((,)) industrial activities; ((, or)) storage of erodible or leachable materials, wastes, or chemicals, and that ((receives)) receive direct rainfall or run-on or blow-in of rainfall; ((,)) use of pesticides and fertilizers; ((,)) or loss of soil. Typical pollution-generating pervious surfaces include lawns, landscaped areas, golf courses, parks, cemeteries, and sports fields (natural and artificial turf).

“Pre-developed condition” means the vegetation and soil conditions that are used to determine the allowable post-development discharge peak flow rates and flow durations, such as pasture or forest.

“Private drainage system” means a drainage system that is not a public drainage system.

“Project” means ((the addition or replacement of hard surface or the undertaking of land disturbing activity on a site)) any proposed action to alter or develop a site. Development is a type of project.

“Project site” means that portion of a property, properties, or rights-of-way subject to ((addition or replacement of hard surface or the undertaking of land disturbing activity)) land disturbing activities, new hard surfaces, or replaced hard surfaces.

“Public combined sewer” means a publicly owned and maintained system which carries drainage water and wastewater and flows to a publicly owned treatment works.

“Public drainage system” means a drainage system owned or operated by ((the)) The City of Seattle.

“Public place” means and includes streets, avenues, ways, boulevards, drives, places, alleys, sidewalks, and planting (parking) strips, squares, triangles and right-of-way for public use and the space above or beneath its surface, whether or not opened or improved.

“Public sanitary sewer” means the sanitary sewer that is owned or operated by ((the)) The City of Seattle.

“Public storm drain” means the part of a public drainage system that is wholly or partially piped, owned or operated by a City agency and designed to carry only drainage water.

22.801.190 “R”

“Real property” means “real property” as defined in Chapter 3.110.

“Receiving water” means the surface water, such as a creek, stream, river, lake, wetland or marine water, or groundwater, receiving drainage water. Drainage systems and public combined sewers are not receiving waters.

“Repeat violation” means a prior violation of this subtitle within the preceding five years that became a final order or decision of the Director or a court. The violation does not need to be the same nor occur on one site to be considered repeat.

“Replaced hard surface” or “replacement of hard surface” means, for structures, the removal down to the foundation and replacement ((of hard surfaces down to the foundation)) and, for other hard surfaces, the removal down to existing subgrade or base course and replacement.

“Replaced impervious surface” or “replacement of impervious surface” means, for structures, the removal down to the foundation and replacement ((of impervious surfaces down to the foundation)) and, for other impervious surfaces, the removal down to existing subgrade or base course and replacement.

“Responsible party” means all of the following persons:

1. Owners, operators, and occupants of property; and

2. Any person causing or contributing to a violation of the provisions of this subtitle.

“Right-of-way” means “right-of-way” as defined in Section 23.84A.032.

“Roadway” means “roadway” as defined in Section 23.84A.032.

“Roadway project” means a project located in the public right-of-way that involves the creation of a new or replacement of an existing roadway or alley. The boundary of the public right-of-way shall form the boundary between the parcel and roadway portions of a project.

“Runoff” means the portion of rainfall or other precipitation that becomes surface flow and interflow.

22.801.200 “S”

“Sanitary sewer” means a system that conveys wastewater and is not designed to convey drainage water.

“SDCI” means the Seattle Department of Construction and Inspections.

“SDOT” means the Seattle Department of Transportation.

“Service drain” means “service drain” as defined in Section 21.16.030.

“Side sewer” means “side sewer” as defined in Section 21.16.030.

“Sidewalk” means “sidewalk” as defined in Section 23.84A.036.

“Sidewalk project” means a project for the creation of a new sidewalk or replacement of an existing sidewalk, including any associated planting strip, apron, curb ramp, curb, or gutter, and necessary roadway grading and repair. If the total new plus replaced hard surface in the roadway exceeds 10,000 square feet, the entire project is a roadway project.

“Single-family residential project” means a project that constructs one Single-family Dwelling Unit as defined in subsection 23.84A.032, ((pursuant to Section 23.44.006.A)) and any associated accessory dwelling unit located in land classified as being Single-family Residential 9,600 (SF 9600), Single-family Residential 7,200 (SF 7200), or Single-family Residential 5,000 (SF 5000) pursuant to Section 23.30.010, and the total new plus replaced hard surface is less than ((10,000)) 5,000 square feet. ((, and the total new plus replaced pollution-generating hard surface is less than 5,000 square feet.))

“Site” means the ((lot or parcel, or portion of street, highway or other right-of-way, or contiguous combination thereof, where development is proposed or performed)) area defined by the legal boundaries of a parcel or parcels of land subject to development. For roadway projects, the length of the project site and the right-of-way boundaries define the site.

“Slope” means an inclined ground surface.

“Small lakes” means Bitter Lake, Green Lake and Haller Lake.

“Small project” means a project with:

1. Less than 5,000 square feet of new and replaced hard surface; and

2. Less than one acre of land disturbing activities.

“SMC” means the Seattle Municipal Code.

“Soil” means naturally deposited non-rock earth materials.

“Solid waste” means “solid waste” as defined in Section 21.36.016.

“Source controls” means structures or operations that prevent contaminants from coming in contact with drainage water through physical separation or careful management of activities that are known sources of pollution.

“SPU” means Seattle Public Utilities.

“Standard design” is a design pre-approved by the Director for drainage and erosion control available for use at a site with pre-defined characteristics.

“Standard Plans and Specifications” means the City of Seattle Standard Plans and Specifications for Road, Bridge, and Municipal Construction in effect on the date of permit application.

“Storm drain” means both public storm drain and service drain.

“Stormwater” means runoff during and following precipitation and snowmelt events, including surface runoff, drainage and interflow.

“Stream” means a ((Type 2-5)) Type S, F, Np or Ns water as defined in WAC 222-16-031, or as defined in WAC 222-16-030 after state water type maps are adopted, and is used synonymously with “creek.”

* * *

Section 3. Chapter 22.803 of the Seattle Municipal Code, last amended by Ordinance 124872, is amended as follows:

Chapter 22.803 MINIMUM REQUIREMENTS FOR ALL DISCHARGES AND ALL REAL PROPERTY

* * *

22.803.020 Minimum Requirements for All Discharges and Real Property

A. Requirement to provide documentation and to map infrastructure. The owner is required to make plans, procedures, and schedules required by this subtitle available to the Director when requested. When requested to aid in applying the Stormwater Code, the owner must provide to the Director a complete map of all drainage, side sewer, and plumbing infrastructure on the property.

B. Requirement to report spills, releases, or dumping. A responsible party is required to, at the earliest possible time, but in any case within 24 hours of discovery, report to the Director of SPU a spill, release, dumping, or other situation that has contributed or is likely to contribute pollutants to a public drainage system, a private drainage system, or a receiving water. This reporting requirement is in addition to, and not instead of, any other reporting requirements under federal, state or local laws.

C. Requirements to maintain facilities. All treatment facilities, flow control facilities, drainage control facilities, and drainage systems shall be maintained as ((prescribed)) specified in rules promulgated by the Director in order for these facilities and systems to be kept in continuous working order.

D. Requirements for disposal of waste from maintenance activities. Disposal of waste from maintenance of drainage control facilities shall be conducted in accordance with federal, state and local regulations, including the Minimum Functional Standards for Solid Waste Handling, Chapter 173-304 WAC, guidelines for disposal of waste materials, and, where appropriate, Dangerous Waste Regulations, Chapter 173-303 WAC.

E. Requirements to maintain records of installation and maintenance activities. When a drainage control facility is installed, the party having the facility installed shall make records of the installation and shall identify the party (or parties) responsible for maintenance and operations. The parties shall retain a continuous record of all maintenance and repair activities, and shall retain the records for at least ten years. If a transfer of ownership occurs, these records of installation, repair, and maintenance shall be transferred to the new property owner. These records shall be made available to the Director of SPU during inspection of the facility and at other reasonable times upon request of the Director of SPU.

22.803.030 Minimum Requirements for Source Controls for All Real Property

For all discharges, responsible parties shall implement and maintain source controls to prevent or minimize pollutants from leaving a site or property. Source controls that are required for all real property include, but are not limited to, the following, as further described in rules promulgated by the Director:

A. Eliminate Illicit ((or Prohibited)) Connections and Illicit Discharges. It is the responsibility of the property owner or other responsible party to ensure that all plumbing connections are properly made and that only connections conveying stormwater or permissible discharges pursuant to Section 22.802.030 are connected to the drainage system. When requested to aid in applying the Stormwater Code, the owner must provide to the Director a complete map of all stormwater and plumbing infrastructure on the property.

B. Perform Routine Maintenance. ((of Drainage System.)) All drainage system components, including, but not limited to, catch basins, flow control facilities, treatment facilities, on-site BMPs, and unimproved drainage pathways shall be kept in continuous working order.

C. Dispose of Fluids and Wastes Properly. Solid and liquid wastes must be disposed of in a manner that minimizes the risk of contaminating stormwater.

D. Proper Storage of Solid Wastes. Solid wastes must be stored in a manner that minimizes the risk of contaminating stormwater.

E. Spill Prevention and Cleanup. All property owners having the potential to spill pollutants shall take measures to prevent spills of pollutants and to properly clean up spills that might occur.

F. Provide Oversight and Training for Staff. For businesses and public entities, annually train all employees responsible for the operation, maintenance, or inspection of BMPs, assign oversight responsibilities, and maintain records.

G. ((Site)) Property Maintenance. For businesses and public entities, locate pollution-generating activities away from stormwater pathways where feasible and engage in proper site maintenance to prevent pollutant transport off site, including but not limited to sweeping paved areas and inspecting loading, unloading, storage and parking areas.

H. Rooftop Dog Runs. Dog runs located on private property on rooftops or above-grade plazas must prevent stormwater from the dog run from discharging directly or indirectly to a public drainage system, private drainage system, or receiving water body.

22.803.040 Minimum Requirements for Source Controls For Businesses and Public Entities for Specific Activities

A. For all discharges, source controls shall be implemented, to extent allowed by law, by businesses and public entities for the following specific pollution-generating activities as specified in the joint SPU/SDCI Directors’ Rule titled “Seattle Stormwater Manual” at “Volume 4 - Source Control,” to the extent necessary to prevent prohibited discharges as described in subsection 22.802.020.A through subsection 22.802.020.D, and to prevent contaminants from coming in contact with drainage water or being discharged to the drainage system, public combined sewer, or directly into receiving waters:

1. Fueling at dedicated stations, for new or substantially altered fueling stations.

2. Mobile fueling of vehicles and heavy equipment.

3. In-water and over-water fueling.

4. Maintenance and repair of vehicles and equipment.

5. Concrete and asphalt mixing and production.

6. Concrete pouring, concrete/asphalt cutting, and asphalt application.

7. Recycling, wrecking yard, and scrap yard operations.

8. Storage of liquids in aboveground tanks.

Source controls include, but are not limited to, segregating or isolating wastes to prevent contact with drainage water; enclosing, covering, or containing the activity to prevent contact with drainage water; developing and implementing inspection and maintenance programs; sweeping; and taking management actions such as training employees on pollution prevention.

B. For all discharges except those that drain only to the public combined sewer, source controls shall be implemented, to the extent allowed by law, by businesses and public entities for specific pollution-generating activities as specified in the joint ((SPU/DPD)) SPU/SDCI Directors’ Rule titled “Seattle Stormwater Manual” at “Volume 4 - Source Control,” to the extent necessary to prevent prohibited discharges as described in subsection 22.802.020.A through subsection 22.802.020.C, and to prevent contaminants from coming in contact with drainage water or being discharged to the drainage system or directly into receiving waters. Source controls include, but are not limited to, segregating or isolating wastes to prevent contact with drainage water; enclosing, covering, or containing the activity to prevent contact with drainage water; developing and implementing inspection and maintenance programs; sweeping; and taking management actions such as training employees on pollution prevention.

Section 4. Chapter 22.805 of the Seattle Municipal Code, last amended by Ordinance 124919, is amended as follows:

Chapter 22.805 MINIMUM REQUIREMENTS FOR ALL PROJECTS

22.805.010 General

A. All projects are required to comply with this chapter, even where drainage control review is not required.

B. Closely related projects shall be considered as one project for purposes of applying the Stormwater Code, including but not limited to determining whether the thresholds for applicability of particular Stormwater Code minimum requirements are met. The Director shall determine whether two or more projects are closely related as specified in the joint SPU/SDCI Directors’ Rule titled “Seattle Stormwater Manual” at “Volume 1 - Project Minimum Requirements.”

C. When an application requires preliminary drainage review according to subsection 22.807.020.A, applications for building permits, grading permits, and other construction permits on the site receiving preliminary drainage review shall comply with the provisions of the approved preliminary drainage control plan.

D. In the case of a subdivision under Chapter 23.22 and short plat under Chapter 23.24, unless an adjustment pursuant to subsection 22.800.040.B is approved by the Director, for the purposes of applying the thresholds in Chapter 22.805, the hard surface coverage is the maximum lot coverage allowed per Subtitle III of Title 23, Land Use Code, plus required and proposed pedestrian and vehicular access and amenities, including driveways, walkways, plazas, and patios identified on the preliminary drainage control plan and associated preliminary site plan.

E. Construction of drainage control facilities and drainage systems for plats

1. In the case of a subdivision under Chapter 23.22, drainage control facilities or drainage systems that are identified on the associated preliminary drainage control plan or the approved preliminary plat and will serve multiple proposed lots, parcels, tracts, or rights-of-way shall be constructed prior to approval of the final plat unless a bond is provided according to subsection 23.22.070.C. If a bond is provided in lieu of construction prior to approval of the final plat, the construction permit for the facilities or systems must be issued prior to issuance of any building permit for any other construction within the subdivision and construction of the facilities or systems shall be completed and final inspection approved prior to final inspection approval of any building permit for any other construction within the subdivision and prior to occupancy of any buildings, but in no event later than two years after final plat approval.

2. In the case of a short plat under Chapter 23.24 with shared drainage control facilities or drainage systems that are identified on the preliminary drainage control plan and will serve multiple proposed lots, parcels, tracts, or rights-of-way, the following shall occur:

a. The construction permit for the shared facilities or systems shall be issued prior to issuance of any building permit for any other construction within the lots, parcels, tracts, or rights-of-way served by the shared facilities or systems; and

b. Construction of the shared facilities or systems shall be completed and final inspection approved prior to final inspection approval of any building permit for any other construction within the lots, parcels, tracts, or rights-of-way served by the shared facilities, and prior to occupancy of any buildings on these lots, parcels, or tracts.

((B)) F. No discharge from a site, real property, or drainage facility, directly or indirectly to a public drainage system, private drainage system, or a receiving water within or contiguous to Seattle city limits, may cause or contribute to a prohibited discharge or a known or likely violation of water quality standards in the receiving water or a known or likely violation of the City’s municipal stormwater NPDES permit.

((C)) G. Every permit issued to implement this subtitle shall contain a performance standard requiring that no discharge from a site, real property, or drainage facility, directly or indirectly to a public drainage system, private drainage system, or a receiving water within or contiguous to Seattle city limits, cause or contribute to a prohibited discharge or a known or likely violation of water quality standards in the receiving water or a known or likely violation of the City’s municipal stormwater NPDES permit.

22.805.020 Minimum requirements for all projects

A. Minimum Requirements for Maintaining Natural Drainage Patterns. For all projects, natural drainage patterns shall be maintained and discharges shall occur at the natural location to the maximum extent feasible and consistent with subsection 22.805.020.B. Drainage water discharged from the site shall not cause a significant adverse impact to receiving waters or down-gradient properties. Drainage water retained or infiltrated on the site shall not cause significant adverse impact to up-gradient or down-gradient properties.

B. Minimum Requirements for Discharge Point. The discharge point for drainage water from each site shall be selected using criteria that shall include, but not be limited to, preservation of natural drainage patterns and whether the capacity of the drainage system is adequate for the flow rate and volume. For those projects meeting the drainage review threshold, the proposed discharge point shall be identified in the drainage control plan required by this subtitle, for review and approval or disapproval by the Director.

C. Minimum Requirements for Flood-prone Areas. On sites within flood-prone areas, responsible parties are required to employ procedures to minimize the potential for flooding on the site and to minimize the potential for the project to increase the risk of floods on adjacent or nearby properties. Flood control measures shall include those set forth in other titles of the Seattle Municipal Code and rules promulgated thereunder, including, but not limited to, Chapter 23.60 (Shoreline District), Chapter 25.06 (Floodplain Development) and Chapter 25.09 (Environmentally Critical Areas) of the Seattle Municipal Code.

D. Minimum Requirements for Construction ((Site)) Stormwater Pollution Prevention ((Control)) Plan. Temporary and permanent construction controls shall be used to accomplish the following minimum requirements. All projects are required to meet each of the elements below or document why an element is not applicable. Additional controls may be required by the Director when minimum controls are not sufficient to prevent erosion or transport of sediment or other pollutants from the site.

1. Mark Clearing Limits and Environmentally Critical Areas. Within the boundaries of the project site and prior to beginning land disturbing activities, including clearing and grading, clearly mark all clearing limits, easements, setbacks, all environmentally critical areas and their buffers, and all trees and drainage courses that are to be preserved within the construction area.

2. Retain Top Layer. Within the boundaries of the project site, the duff layer, topsoil, and native vegetation, if there is any, shall be retained in an undisturbed state to the maximum extent feasible. If it is not feasible to retain the top layer in place, it should be stockpiled on-site, covered to prevent erosion, and replaced immediately upon completion of the land disturbing activities to the maximum extent feasible.

3. Establish Construction Access. Limit construction vehicle access, whenever possible, to one route. Stabilize access points and minimize tracking sediment onto public roads. Promptly remove any sediment tracked off site.

4. Protect Downstream Properties and Receiving Waters. Protect properties and receiving waters downstream from the development sites from erosion due to increases in the volume, velocity, and peak flow rate of drainage water from the project site. If it is necessary to construct flow control facilities to meet this requirement, these facilities shall be functioning prior to implementation of other land disturbing activity. If permanent infiltration facilities are used to control flows during construction, these facilities shall be protected from siltation during the construction phase of the project.

5. Prevent Erosion and Sediment Transport from the Site. Pass all drainage water from disturbed areas through a sediment trap, sediment pond, or other appropriate sediment removal BMP before the water leaves the site or prior to discharge to an infiltration facility. Sediment controls intended to trap sediment on site shall be constructed as one of the first steps in grading and shall be functional before other land disturbing activities take place. BMPs intended to trap sedimentation shall be located in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal and maximize stormwater infiltration where feasible.

6. Prevent Erosion and Sediment Transport from the Site by Vehicles. Whenever construction vehicle access routes intersect paved roads, the transport of sediment onto the paved road shall be minimized. If sediment is transported onto a paved road surface, the roads shall be cleaned thoroughly at the end of each day. Sediment shall be removed from paved roads by shoveling or sweeping and shall be transported to a controlled sediment disposal area. If sediment is tracked off site, roads shall be cleaned thoroughly at the end of each day, or at least twice daily during wet weather. Street washing is allowed only after sediment is removed, and street wash wastewater shall be prevented from entering the drainage system and receiving waters.

7. Stabilize Soils. Prevent on-site erosion by stabilizing all exposed and unworked soils, including stock piles and earthen structures such as dams, dikes, and diversions. From October 1 to April 30, no soils shall remain exposed and unworked for more than two days. From May 1 to September 30, no soils shall remain exposed for more than seven days. Soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Soil stockpiles shall be stabilized from erosion, protected with sediment trapping measures, and be located away from storm drain inlets, waterways, and drainage channels. Before the completion of the project, permanently stabilize all exposed soils that have been disturbed during construction.

8. Protect Slopes. Erosion from slopes shall be minimized. Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion. Off-site stormwater run-on or groundwater shall be diverted away from slopes and undisturbed areas with interceptor dikes, pipes, and/or swales. Pipe slope drains or protected channels shall be constructed at the top of slopes to collect drainage and prevent erosion. Excavated material shall be placed on the uphill side of trenches, consistent with safety and space considerations. Check dams shall be placed at regular intervals within constructed channels that are cut down a slope.

9. Protect Storm Drains. Prevent sediment from entering all storm drains, including ditches that receive drainage water from the project. Storm drain inlets protection devices shall be cleaned or removed and replaced as recommended by the product manufacturer, or more frequently if required to prevent failure of the device or flooding. Storm drain inlets made operable during construction shall be protected so that drainage water does not enter the drainage system without first being filtered or treated to remove sediments. Storm drain inlet protection devices shall be removed at the conclusion of the project. When manufactured storm drain inlet protection devices are not feasible, inlets and catch basins must be cleaned as necessary to prevent sediment from entering the drainage control system.

10. Stabilize Channels and Outlets. All temporary on-site drainage systems shall be designed, constructed, and stabilized to prevent erosion. Stabilization shall be provided at the outlets of all drainage systems that is adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches.

11. Control Pollutants. Measures shall be taken to control potential pollutants and shall include, but not be limited to, the following measures:

a. All pollutants, including sediment, waste materials, and demolition debris, that occur ((onsite)) on site shall be handled and disposed of in a manner that does not cause contamination of drainage water and pursuant to all applicable disposal laws.

b. Containment, cover, and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment.

c. On-site fueling tanks shall include secondary containment.

d. Maintenance, fueling, and repair of heavy equipment and vehicles involving oil changes, hydraulic system drain down, solvent and de-greasing 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 drainage water runoff shall be conducted using spill prevention and control measures.

e. Contaminated soils shall be removed and surfaces shall be cleaned immediately following any discharge or spill incident.

f. Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system that prevents discharge to surface water, ((such as closed-loop recirculation or upland application,)) or to the sanitary sewer or combined sewer system with approval of the Director of SPU. Temporary discharges or connections to the public sanitary and combined sewers shall be made in accordance with Chapter 21.16 (Side Sewer Code).

g. Application of fertilizers and pesticides shall be conducted in a manner and at application rates that will not result in loss of chemical to drainage water. Manufacturers’ label requirements for application rates and procedures shall be followed.

h. BMPs shall be used to prevent or treat contamination of drainage water by pH-modifying sources. These sources include, but are not limited to, recycled concrete stockpiles, 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. Construction site operators may be required to adjust the pH of drainage water if necessary to prevent a violation of water quality standards.

i. Construction site operators must obtain written approval from Ecology prior to using chemical treatment other than carbon dioxide (CO2) ((or)) dry ice, or food grade vinegar, to adjust pH.

j. Uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations may be infiltrated provided the wastewater is managed in a way that prevents discharge to surface waters. Prior to infiltration, water from water-only based shaft drilling that comes into contact with curing concrete must be neutralized until pH is in the range of 6.5 to 8.5 (su).

k. Train all employees on proper BMPs for preventing illicit discharges, including spills.

12. Control Dewatering. When dewatering devices discharge on site, to a public drainage system, or to the public combined sewer, dewatering devices shall discharge into a sediment trap, sediment pond, gently sloping vegetated area of sufficient length to remove sediment contamination, or other sediment removal BMP. Foundation, vault, and trench dewatering waters must be discharged into a controlled drainage system prior to discharge to a sediment trap or sediment pond. Clean, non-turbid dewatering water, such as well-point groundwater, that is discharged to systems tributary to state surface waters must not cause erosion or flooding. Highly turbid or contaminated dewatering water shall be handled separately from drainage water. For any project with an excavation depth of 12 feet or more below the existing grade and for all large projects, dewatering flows must be determined and it must be verified that there is sufficient capacity in the public drainage system and public combined sewer prior to discharging.

13. Maintain BMPs. 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 temporary erosion and sediment controls shall be removed within five days after final site stabilization is achieved or after the temporary controls are no longer needed, whichever is later. Trapped sediment shall be removed or stabilized on site. Disturbed soil areas resulting from removal shall be permanently stabilized.

14. Inspect BMPs. BMPs shall be periodically inspected. For projects with 5,000 square feet or more of new plus replaced hard surface or 7,000 square feet or more of land disturbing activity, site inspections shall be conducted by a Certified Erosion and Sediment Control Lead who shall be identified prior to construction and shall be present on-site or on-call at all times.

15. Execute Construction Stormwater Control Plan. Construction site operators shall maintain, update, and implement their Construction Stormwater Control Plan. Construction site operators shall modify their Construction Stormwater Control Plan to maintain compliance whenever there is a change in design, construction, operation, or maintenance at the site that has, or could have, a significant effect on the discharge of pollutants to waters of the state.

16. Minimize Open Trenches. In the construction of underground utility lines, where feasible, no more than 150 feet of trench shall be opened at one time, unless soil is replaced within the same working day, and where consistent with safety and space considerations, excavated material shall be placed on the uphill side of trenches. Trench dewatering devices shall discharge into a sediment trap or sediment pond.

17. Phase the Project. Development projects shall be phased to the maximum extent feasible in order to minimize the amount of land disturbing activity occurring at the same time and shall take into account seasonal work limitations.

18. Install Flow Control and Water Quality Facilities. Development projects required to comply with Section 22.805.080 (Minimum Requirements for Flow Control) or Section 22.805.090 (Minimum Requirements for Treatment) shall install permanent flow control and water quality facilities to prevent erosion or transport of sediment or other pollutants from the site during construction.

19. Protect Stormwater BMPs

a. Protect all stormwater BMPs from sedimentation through installation and maintenance of erosion and sediment control BMPs. Restore the BMPs to their fully functioning condition if they accumulate sediment during construction. Restoring the stormwater BMP must include removal of sediment and any sediment-laden stormwater BMP soils, and replacing the removed soils with soils meeting the design specification.

b. Prevent compacting on-site BMPs by excluding construction equipment and foot traffic. Protect completed lawn and landscaped areas from compaction due to construction equipment.

c. Control erosion and avoid introducing sediment from surrounding land uses onto permeable pavements. Do not allow muddy construction equipment on the base material or pavement. Do not allow sediment-laden runoff onto permeable pavements or base materials.

d. Permeable pavements fouled with sediments or no longer passing an initial infiltration test must be cleaned until infiltrating per design or replaced.

e. Keep all heavy equipment off existing soils under on-site BMPs that have been excavated to final grade, to retain the infiltration rate of the soils.

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I. Install Source Control BMPs. Source control BMPs shall be installed for discharges, properties, and by businesses and public entities for specific pollution-generating activities as specified in Chapter 22.803 and in the joint ((SPU/DPD)) SPU/SDCI Directors’ Rule titled “Seattle Stormwater Manual” at “Volume 4 - Source Control,” to the extent necessary to prevent prohibited discharges as described in Section 22.802.020 and to prevent contaminants from coming in contact with drainage water. This requirement applies to the pollution-generating activities that are stationary or occur in one primary location and to the portion of the site being developed. Examples of installed source controls include, but are not limited to, the following:

1. A roof, awning, or cover erected over the pollution-generating activity area;

2. Ground surface treatment in the pollution-generating activity area to prevent interaction with, or breakdown of, materials used in conjunction with the pollution-generating activity;

3. Containment of drainage from the pollution-generating activity to a closed sump or tank. Contents of such a sump or tank must be pumped or hauled by a waste handler, or treated prior to discharge to a public drainage system; ((.))

4. Construct a berm or dike to enclose or contain the pollution-generating activities;

5. Direct drainage from containment area of pollution-generating activity to a closed sump or tank for settling and appropriate disposal, or treat prior to discharging to a public drainage system;

6. Pave, treat, or cover the containment area of pollution-generating activities with materials that will not interact with or break down in the presence of other materials used in conjunction with the pollution-generating activity; and

7. Prevent precipitation from flowing or being blown onto containment areas of pollution-generating activities.

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L. Extension of the Public Drainage System for Projects Not Constructed in the Public Right-of-Way. For projects not constructed in the public right-of-way, extension of the piped public drainage system across the full extent of the parcel boundary in the abutting public place shall be required for any of the following:

1. All projects where the Director has determined an extension is required considering, but not limited to, the following attributes of the project:

a. Poses a hazard to public health, safety, or welfare;

b. Endangers any property;

c. Adversely affects the safety and operation of public right-of-way, utilities, or other property owned or maintained by the City;

d. Adversely affects the functions and values of an environmentally critical area or buffer;

e. Adversely affects an area with known erosion or flooding problems; or

f. Adversely affects receiving waters, any properties, or right-of-way.

2. All projects with 5,000 square feet or more of new plus replaced hard surface, unless:

a. The piped public drainage system is already accessible within an abutting public place to each existing, proposed, or adjusted parcel; or

b. The project is otherwise not required to extend by rules promulgated by the Director.

M. Extension of the Public Drainage System for Projects Constructed in the Public Right-of-Way. For projects constructed in the public right-of-way, extension of the piped public drainage system across the full extent of the site shall be required for any of the following:

1. All projects where the Director has determined an extension is required considering, but not limited to, the following attributes of the project:

a. Poses a hazard to public health, safety, or welfare;

b. Endangers any property;

c. Adversely affects the safety and operation of City right-of-way, utilities, or other property owned or maintained by the City;

d. Adversely affects the functions and values of an environmentally critical area or buffer;

e. Adversely affects an area with known erosion or flooding problems; or

f. Adversely affects receiving waters, any properties, or right-of-way.

2. The project’s total new plus replaced hard surface is 50 percent or more of the existing hard surfaces within the project limits. The project limits are defined by the length of the project and the width of the right-of-way. If a project encompasses more than one intersection, the project limits are further defined by one intersection to the other and blocks may vary in length, unless:

a. The piped public drainage system is already accessible within the site across the full extent of the site; or

b. The project is otherwise not required to extend by rules promulgated by the Director.

N. Public Drainage System Requirements. Public drainage systems shall be constructed in accordance with the City’s Standard Plans and Specifications, SPU’s Design Standards and Guidelines, and as specified in rules promulgated by the Director of SPU.

22.805.030 Minimum Requirements for Single-Family Residential Projects

A. Soil Amendment. Retain and protect undisturbed soil in areas not being developed, and prior to completion of the project, amend all new, replaced, and disturbed topsoil (including construction lay-down areas) with organic matter to the extent required by and in compliance with the rules promulgated by the Director.

B. On-site Stormwater Management. Single-family residential projects shall meet the Minimum Requirements for On-site Stormwater Management contained in Section 22.805.070, to the extent allowed by law, if:

1. For a project on a lot most recently created, adjusted, altered, or otherwise amended by a plat or other lawful document recorded with the King County Recorder on or after January 1, 2016, and where that document either created the lot or ((reduced)) altered the size of the lot, either the total new plus replaced hard surface is 750 square feet or more or land disturbing activity is 7,000 square feet or more; or

2. For any other project, either the total new plus replaced hard surface is 1,500 square feet or the land disturbing activity is 7,000 square feet or more.

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22.805.050 Minimum Requirements for Parcel-Based Projects

A. Soil Amendment. Retain and protect undisturbed soil in areas not being developed, and prior to completion of the project, amend all new, replaced, and disturbed topsoil (including construction lay-down areas) with organic matter to the extent required by and in compliance with the rules promulgated by the Director.

B. On-site Stormwater Management. Parcel-based projects shall meet the Minimum Requirements for On-site Stormwater Management contained in Section 22.805.070, to the extent allowed by law, if:

1. For a project on a lot most recently created, adjusted, altered, or otherwise amended by a plat or other lawful document recorded with the King County Recorder on or after January 1, 2016, and where that document either created the lot or ((reduced)) altered the size of the lot, either the total new plus replaced hard surface is 750 square feet or more or land disturbing activity is 7,000 square feet or more; or

2. For any other project, either the total new plus replaced hard surface is 1,500 square feet or more or the land disturbing activity is 7,000 square feet or more.

C. Flow Control. Parcel-based projects shall meet the minimum requirements for flow control contained in Section 22.805.080, to the extent allowed by law, as prescribed below.

1. Discharges to Wetlands. Parcel-based projects discharging into a wetland, or to the drainage basin of a wetland, shall:

a. Comply with Section 22.805.020 (Minimum requirements for all projects), including, but not limited to subsection 22.805.020.E (Protect Wetlands).

b. ((comply)) Comply with the minimum requirements for wetland protection contained in subsection 22.805.080.B.1 (Wetland Protection Standards) if:

((a.)) 1) The total new plus replaced hard surface is 5,000 square feet or more; or

((b.)) 2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

((c.)) 3) The project converts 2.5 acres or more of native vegetation to pasture and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site.

2. Discharges to Listed Creek Basins. Parcel-based projects discharging into Blue Ridge Creek, Broadview Creek, Discovery Park Creek, Durham Creek, Frink Creek, Golden Gardens Creek, Kiwanis Ravine/Wolfe Creek, Licton Springs Creek, Madrona Park Creek, Mee-Kwa-Mooks Creek, Mount Baker Park Creek, Puget Creek, Riverview Creek, Schmitz Creek, Taylor Creek, or Washington Park Creek, or to the drainage basin of such creek, shall:

a. Comply with subsection 22.805.080.B.2 (Pre-developed Forested Standard) if the existing hard surface coverage is less than 35 percent and one or more of the following apply:

1) The project adds 5,000 square feet or more of new hard surface and the total new plus replaced hard surface is 10,000 square feet or more; or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

4) The project adds 5,000 square feet or more of new hard surface and, through a combination of effective hard surfaces and converted pervious surfaces, causes a ((0.1)) 0.15 cubic feet per second increase in the 100-year recurrence interval flow frequency as estimated using a continuous model approved by the Director.

b. Comply with subsection 22.805.080.B.3 (Pre-developed Pasture Standard) if the criteria in subsection 22.805.050.C.2.a do not apply and one or more apply:

1) ((the)) The total new plus replaced hard surface is ((2,000)) 5,000 square feet or more; ((.)) or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture, and from the project there is a surface discharge into a natural or constructed conveyance system from the site.

3. Discharges to Non-listed Creek Basins. Parcel-based projects discharging into a creek not listed in subsection 22.805.050.C.2, or to the drainage basin of such creek, shall:

a. Comply with subsection 22.805.080.B.2 (Pre-developed Forested Standard) if the existing land cover is forested and one or more of the following apply:

1) The project adds 5,000 square feet or more of new hard surface and the total new plus replaced hard surface is 10,000 square feet or more; or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

4) The project adds 5,000 square feet or more of new hard surface and, through a combination of effective ((impervious)) hard surfaces and converted pervious surfaces, causes a ((0.1)) 0.15 cubic feet per second increase in the 100-year recurrence interval flow frequency as estimated using a continuous model approved by the Director.

b. Comply with subsection 22.805.080.B.3 (Pre-developed Pasture Standard) if the criteria in subsection 22.805.050.C.3.a do not apply and one or more of the following apply:

1) ((the)) The total new plus replaced hard surface is ((2,000)) 5,000 square feet or more; ((.)) or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture, and from the project there is a surface discharge into a natural or constructed conveyance system from the site.

4. Discharges to Small Lake Basins. Parcel-based projects discharging into Bitter Lake, Green Lake, or Haller Lake, or to the drainage basin of such lake, shall comply with subsection ((22.805.080.B.4)) 22.805.080.B.5 (Peak Control Standard) if the total new plus replaced hard surface is 2,000 square feet or more.

5. Discharges to Public Combined Sewer. Unless the Director of SPU has determined that the public combined sewer has sufficient capacity to carry existing and anticipated loads, parcel-based projects discharging into the public combined sewer or its basin shall comply with subsection ((22.805.080.B.4)) 22.805.080.B.5 (Peak Control Standard) if the total new plus replaced hard surface is ((10,000)) 5,000 square feet or more.

6. Discharges to a Capacity-constrained System. In addition to applicable minimum requirements for flow control in subsection 22.805.050.C.1 through subsection 22.805.050.C.5, parcel-based projects discharging into a capacity-constrained system or its basin shall also comply with subsection ((22.805.080.B.4)) 22.805.080.B.5 (Peak Control Standard) if the total new plus replaced hard surface is 2,000 square feet or more unless the downstream system only includes ditches or culverts and the system has been determined to have sufficient capacity as specified in subsection 22.805.020.H (Ensure Sufficient Capacity).

7. Discharges from Groundwater. In addition to applicable minimum requirements for flow control in subsection 22.805.050.C.1 through subsection 22.805.050.C.6, parcel-based projects that will permanently discharge groundwater to a public drainage system or to a public combined sewer shall also comply with subsection ((22.805.080.B.4)) 22.805.080.B.5 (Peak Control Standard) if the total new plus replaced hard surface is 2,000 square feet or more.

D. Treatment. Parcel-based projects not discharging to the public combined sewer shall comply with the minimum requirements for treatment contained in Section 22.805.090 for flows from the total new plus replaced pollution-generating hard surface and the new plus replaced pollution-generating pervious surface, to the extent allowed by law, if:

1. The total new plus replaced pollution-generating hard surface is 5,000 square feet or more; or

2. The total new plus replaced pollution-generating pervious surfaces is 3/4 acres or more, and from the project there is a surface discharge in a natural or ((man-made)) constructed conveyance system from the site.

22.805.060 Minimum Requirements for Roadway Projects

A. Soil Amendment. Retain and protect undisturbed soil in areas not being developed, and prior to completion of the project, amend all new, replaced, and disturbed topsoil (including construction lay-down areas) with organic matter to the extent required by and in compliance with the rules promulgated by the Director.

B. On-Site Stormwater Management. All roadway projects with 2,000 square feet or more of new plus replaced hard surface or 7,000 square feet or more of land disturbing activity shall meet the Minimum Requirements for On-site Stormwater Management contained in Section 22.805.070, to the extent allowed by law, except as provided in subsection 22.805.060.E.

C. Flow Control. Roadway projects shall meet the minimum requirements for flow control contained in Section 22.805.080, to the extent allowed by law, as prescribed below, except as provided in subsection 22.805.060.E.

1. Discharges to Wetlands. Roadway projects discharging into a wetland or to the drainage basin of a wetland, shall:

a. Comply with Section 22.805.020 (Minimum requirements for all projects), including, but not limited to subsection 22.805.020.E (Protect Wetlands).

b. ((comply)) Comply with the minimum requirements for wetland protection contained in subsection 22.805.080.B.1 (Wetland Protection Standards) if the existing hard surface coverage is less than 35 percent and one or more of the following apply:

((a.)) 1) The total new plus replaced hard surface is 5,000 square feet or more; or

((b.)) 2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

((c.)) 3) The project converts 2.5 acres or more of native vegetation to pasture and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site.

c. Comply with the minimum requirements for wetland protection contained in subsection 22.805.080.B.1 (Wetland Protection Standards) if the existing hard surface coverage is greater than or equal to 35 percent and one or more of the following apply:

1) The total new hard surface is 10,000 square feet or more; or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture and from the project there is a surface discharge into a natural or constructed conveyance system from the site.

2. Discharges to Listed Creek Basins. Roadway projects discharging into Blue Ridge Creek, Broadview Creek, Discovery Park Creek, Durham Creek, Frink Creek, Golden Gardens Creek, Kiwanis Ravine/Wolfe Creek, Licton Springs Creek, Madrona Park Creek, Mee-Kwa-Mooks Creek, Mount Baker Park Creek, Puget Creek, Riverview Creek, Schmitz Creek, Taylor Creek, or Washington Park Creek, or to the drainage basin of such creek, shall:

a. Comply with subsection 22.805.080.B.2 (Pre-developed Forested Standard) if the existing hard surface coverage is less than 35 percent and one or more of the following apply:

1) The project adds 5,000 square feet or more of new hard surface and the total new plus replaced hard surface is 10,000 square feet or more; or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

4) The project adds 5,000 square feet or more of new hard surface and, through a combination of effective hard surfaces and converted pervious surfaces, causes a ((0.1)) 0.15 cubic feet per second increase in the 100-year recurrence interval flow frequency as estimated using a continuous model approved by the Director.

b. Comply with subsection ((22.805.080.B.3 (Pre-developed Pasture Standard))) 22.805.080.B.4 (Existing Condition Standard) if the criteria in subsection 22.805.060.C.2.a do not apply and the total new ((plus replaced)) hard surface is 10,000 square feet or more, ((.)) and:

1) If the new hard surface adds 50 percent or more to the existing hard surfaces within the project limits, comply with subsection 22.805.080.B.4 (Existing Condition Standard) for the flows from the total new plus replaced hard surfaces. The project limits are defined by the length of the project and the width of the right-of-way; or

2) If the new hard surface adds less than 50 percent to the existing hard surfaces within the project limits, comply with subsection 22.805.080.B.4 (Existing Condition Standard) for the flows from the total new hard surfaces. The project limits are defined by the length of the project and the width of the right-of-way.

3. Discharges to Non-listed Creek Basins. Roadway projects discharging into a creek not listed in subsection 22.805.060.C.2, or to the drainage basin of such creek, shall:

a. Comply with subsection 22.805.080.B.2 (Pre-developed Forested Standard) if the existing land cover is forested and one or more of the following apply:

1) The project adds 5,000 square feet or more of new hard surface and the total new plus replaced hard surface is 10,000 square feet or more; or

2) The project converts 3/4 acres or more of vegetation to lawn or landscaped areas, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

3) The project converts 2.5 acres or more of native vegetation to pasture, and from the project there is a surface discharge into a natural or ((man-made)) constructed conveyance system from the site; or

4) The project adds 5,000 square feet or more of new hard surface and, through a combination of effective hard surfaces and converted pervious surfaces, causes a ((0.1)) 0.15 cubic feet per second increase in the 100-year recurrence interval flow frequency as estimated using a continuous model approved by the Director.

b. Comply with subsection ((22.805.080.B.3 (Pre-developed Pasture Standard))) 22.805.080.B.4 (Existing Condition Standard) if the criteria in subsection 22.805.060.C.3.a do not apply and the total new ((plus replaced)) hard surface is 10,000 square feet or more, ((.)) and:

1) If the new hard surface adds 50 percent or more to the existing hard surfaces within the project limits, comply with subsection 22.805.080.B.4 (Existing Condition Standard) for the flows from the total new plus replaced hard surfaces. The project limits are defined by the length of the project and the width of the right-of-way; or

2) If the new hard surface adds less than 50 percent to the existing hard surfaces within the project limits, comply with subsection 22.805.080.B.4 (Existing Condition Standard) for the flows from the total new hard surfaces. The project limits are defined by the length of the project and the width of the right-of-way.

4. Discharges to Small Lake Basins. ((Projects)) Roadway projects discharging into Bitter Lake, Green Lake, or Haller Lake, or to the drainage basin of such lake, shall comply with subsection 22.805.080.B.4 (((Peak Control Standard))) (Existing Condition Standard) if the total new ((plus replaced)) hard surface is 10,000 square feet or more, ((.)) and:

a. If the new hard surface adds 50 percent or more to the existing hard surfaces within the project limits, comply with subsection 22.805.080.B.4 (Existing Condition Standard) for the flows from the total new plus replaced hard surfaces. The project limits are defined by the length of the project and the width of the right-of-way; or

b. If the new hard surface adds less than 50 percent to the existing hard surfaces within the project limits, comply with subsection 22.805.080.B.4 (Existing Condition Standard) for the flows from the total new hard surfaces. The project limits are defined by the length of the project and the width of the right-of-way.

((5. Discharges to Public Combined Sewer. Unless the Director of SPU has determined that the public combined sewer has sufficient capacity to carry existing and anticipated loads, roadway projects discharging into the public combined sewer or its basin shall comply with subsection 22.805.080.B.4 (Peak Control Standard) if the total new plus replaced hard surface is 10,000 square feet or more.

6)) 5. Discharges to a Capacity-constrained System. In addition to applicable minimum requirements for flow control in subsection 22.805.060.C.1 through subsection ((22.805.060.C.5)) 22.805.060.C.4, roadway projects discharging into a capacity-constrained system or its basin shall also comply with subsection 22.805.080.B.4 (((Peak Control Standard))) (Existing Condition Standard) if the total new ((plus replaced)) hard surface is 10,000 square feet or more unless the downstream system only includes ditches or culverts and has been determined to have sufficient capacity as specified in 22.805.020.H (Ensure Sufficient Capacity).

((7. Discharges from Groundwater. In addition to applicable minimum requirements for flow control in subsection 22.805.060.C.1 through subsection 22.805.060.C.6, roadway projects that will permanently discharge groundwater to a public drainage system or to a public combined sewer shall also comply with subsection 22.805.080.B.4 (Peak Control Standard) if the total new plus replaced hard surface is 10,000 square feet or more.))

D. Treatment. Roadway projects not discharging to the public combined sewer shall, to the extent allowed by law, except as provided in subsection 22.805.060.E:

1. If the site has less than 35 percent existing hard surface coverage, and the project’s total new plus replaced pollution-generating hard surface is 5,000 square feet or more, comply with the minimum requirements for treatment contained in Section 22.805.090 for flows from the total new plus replaced pollution-generating hard surface and new plus replaced pollution-generating pervious surface; and

2. If the site has greater than or equal to 35 percent existing ((impervious)) hard surface coverage and the project’s total new pollution-generating hard surface is 5,000 square feet or more, and

a. If the new pollution-generating hard surface adds 50 percent or more to the existing hard surfaces within the project limits, comply with the minimum requirements for treatment contained in Section 22.805.090 for flows from the total new plus replaced pollution-generating hard surface and new plus replaced pollution-generating pervious surface. The project limits are defined by the length of the project and the width of the right-of-way; or

b. If the new pollution-generating hard surface adds less than 50 percent to the existing hard surfaces within the project limits, comply with the minimum requirements for treatment contained in Section 22.805.090 for flows from the total new pollution-generating hard surface and new pollution-generating pervious surface. The project limits are defined by the length of the project and the width of the right-of-way; and

3. If the total new plus replaced pollution-generating pervious surfaces is 3/4 acres or more, and from the project there is a surface discharge in a natural or ((man-made)) constructed conveyance system from the site, comply with the minimum requirements for treatment contained in Section 22.805.090 for flows from the total new plus replaced pollution-generating pervious surface and the new plus replaced pollution-generating hard surface.

E. For a roadway project that adds less than 50 percent to the existing hard surface within the project limits on a site having greater than 35 percent existing hard surface coverage, the requirements of subsections 22.805.060.B, 22.805.060.C and 22.805.060.D to install drainage control facilities are modified based on infeasibility to the degree that (((a))) (1) complete installation would require that an existing major publicly or privately ((-)) owned infrastructure or utility element be relocated, or (((b))) (2) the drainage control facility cannot be built and operated to discharge stormwater from the site under gravity flow conditions while meeting the applicable engineering standards. Compliance with subsections 22.805.060.B, 22.805.060.C and 22.805.060.D is required to the degree that the project can avoid the infeasibility described in this subsection 22.805.060.E. Standard drainage ((control)) review and approval shall be required whenever this subsection is used, whether or not Section 22.800.070 applies.

1. The following are considered existing major infrastructure or utility elements:

a. Gravity flow pipe greater than or equal to 24 inches in diameter or gravity flow pipe which cannot be relocated to discharge under gravity flow conditions;

b. High-pressure gas pipe;

c. Pressure gas pipe greater than 8 inches in diameter;

d. Any other pressure pipe greater than 12 inches in diameter (e.g., water or steam);

e. Duct banks, vaults, or handholes, for underground electrical, fiber optic, or telecommunication services;

f. Bridge, building, or tunnel structural foundations; and

g. Foundations for walls greater than 6 feet in height or 15 feet in length.

22.805.070 Minimum Requirements for ((On-Site)) On-site Stormwater Management

A. Applicability. The requirements of this subsection 22.805.070 apply as required in Section 22.805.030 to Section 22.805.060.

B. Requirements. On-site stormwater management shall be installed to the extent allowed by law and maintained in compliance with the rules promulgated by the Director to receive flows from that portion of the site being developed and shall:

1. Comply with either:

a. Subsection 22.805.070.C (On-site Performance Standard); or

b. Subsection 22.805.070.D (On-site Lists).

C. On-site Performance Standard:

1. If the existing hard surface coverage is less than 35 percent and the project discharges to a listed creek, or to the drainage basin of such creek:

a. The post-development discharge durations shall match the discharge durations of a pre-developed forested condition for the range of pre-developed discharge rates from 8 percent of the 2-year peak flow to 50 percent of the 2-year peak flow.

2. For all other projects:

a. The post-development discharge durations shall match the discharge durations of a pre-developed pasture condition for the range of pre-developed discharge rates between the 1 percent and 10 percent exceedance values.

D. On-site Lists:

1. For each project surface, follow the appropriate project table in subsection 22.805.070.D.2 to subsection 22.805.070.D.5 to evaluate on-site BMPs shown for that type of surface, by category. The project tables apply to roofs and other hard (non-roof) surfaces. All on-site BMPs used must comply with the rules promulgated by the Director. For each surface, consider all of the applicable on-site BMPs in the first category. Use any that is considered feasible. If none is feasible for that surface, move on to each successive category and repeat the selection process as necessary. Once one on-site BMP is used for a surface, no other on-site BMP is necessary for that surface. If no BMP in the appropriate categories is feasible, then no further evaluation is required for that surface under this subsection 22.805.070.D.1. Feasibility shall be determined by evaluation against:

a. Design criteria, minimum size, limitations, and infeasibility criteria identified for each BMP in this subsection and the rules promulgated by the Director; and

b. Competing Needs: Subsection 22.805.070.D (On-site Lists) can be superseded or reduced by the Director if the installation of the BMPs is in conflict with:

1) Any of the following federal or state laws, rules, and standards, as may be amended or superseded: Historic Preservation and Archaeology Laws identified in subsection 22.805.070.E (Historic Preservation and Archaeology Laws), Federal Superfund or Washington State Model Toxics Control Act, Federal Aviation Administration requirements for airports, the Americans with Disabilities Act, and related rules and standards; or

2) Special zoning district design criteria adopted and being implemented pursuant to a community planning process. Special zoning districts include, for example, historic and preservation districts, pedestrian zone overlays, station area overlays, special review districts, multifamily residential zones, urban centers and urban villages, and master planned communities. Specific criteria in these areas include, but are not limited to, minimum Floor Area Ratio standards; zero lot line development; usable open space requirements; minimum sidewalk width and required bicycle facilities; alley, loading, and access requirements; pitched roof standards; and street-level development standards for modulation and projections; or

3) Public health and safety standards; or

4) Transportation regulations to maintain the option for future expansion or multi-modal use of public rights-of-way; or

5) Chapter 15.43 (Tree and Vegetation Management in Public Places); Chapter 25.09 (Regulations for Environmentally Critical Areas); Chapter 25.11 (Tree Protection); and Chapter 23.60A (Standards for Vegetation in the Shoreline Master Plan).

2. For single-family residential projects, Table A for 22.805.070 applies.

Table A for 22.805.070  On-site List for Single-family Residential Projects

Category

BMPs

All Discharge Locations

1

Full Dispersion

R, S

 

Infiltration Trenches

R, S d

 

((Dry Wells)) Drywells

R, S d

2

Rain Gardens a

R, S

 

Infiltrating Bioretention

R, S

 

Rainwater Harvesting-Category 2 Sizing

X b

 

Permeable Pavement Facilities

R, S

 

Permeable Pavement Surfaces

S

 

Sidewalk/Trail Compost-Amended Strip

S

3

Sheet Flow Dispersion

R, S

 

Concentrated Flow Dispersion

S

 

Splashblock Downspout Dispersion

R

 

Trench Downspout Dispersion

R

 

((Non-infiltrating Bioretention))

((R, S))

 

((Vegetated Roofs))

((X))

4

Non-infiltrating Bioretention

R, S

 

Rainwater Harvesting-Category 4 Sizing

X c

 

Vegetated Roofs

X

((4)) 5

Single-family Residential Cisterns

R

 

Perforated Stub-out Connections

R

 

((Newly Planted)) Trees

S

Note that subsection 22.805.070.D.1 requires consideration of all on-site BMPs in a category for feasibility before moving on to each successive category as necessary. Within a category, BMPs may be considered in any order. Key to Table A for 22.805.070  R = Evaluation is required for all roof runoff from Single-family residential projects. S = Evaluation is required for all other hard (non-roof) surfaces of Single-family residential projects, unless otherwise noted below. X = Evaluation is not required but is allowed. a Installation is only allowed for projects with less than 5,000 square feet of hard surface infiltrating on the project site. b Category 2 rainwater harvesting shall be sized to meet the on-site performance standard, subsection 22.805.070.C. c Category 4 rainwater harvesting shall be sized to reduce the runoff volume by 25 percent or more on an annual average basis. d Evaluation of other hard (non-roof) surfaces is not required but is allowed.

3. For trail and sidewalk projects, Table B for 22.805.070 applies.

Table B for 22.805.070  On-site List for Trail and Sidewalk Projects