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HomeMy WebLinkAboutORD 5526CITY OF RENTON, WASHINGTON ORDINANCE NO. 5526 AN ORDINANCE OF THE CITY OF RENTON, WASHINGTON, AMENDING CHAPTER 2, ZONING DISTRICTS - USES AND STANDARDS; CHAPTER 3, ENVIRONMENTAL REGULATIONS AND OVERLAY DISTRICTS; CHAPTER 4, CITY-WIDE PROPERTY DEVELOPMENT REGULATIONS; CHAPTER 6, STREET AND UTILITY STANDARDS; CHAPTER 8, PERMITS - GENERAL AND APPEALS; CHAPTER 9, PERMITS - SPECIFIC; AND CHAPTER 11, DEFINITIONS, OF TITLE IV (DEVELOPMENT REGULATIONS) OF ORDINANCE NO. 4260 ENTITLED "CODE OF GENERAL ORDINANCES OF THE CITY OF RENTON, WASHINGTON" TO AMEND DRAINAGE REGULATIONS AND ADOPT BY REFERENCE PORTIONS OF THE KING COUNTY SURFACE WATER DESIGN MANUAL AND AMENDMENTS THERETO. THE CITY COUNCIL OF THE CITY OF RENTON, WASHINGTON, DOES ORDAIN AS FOLLOWS: SECTION I. The row labeled "R-l" in the Maximum Building Coverage section of subsection 4-2-110A, Development Standards for Residential Zoning Designations (Primary and Attached Accessory Structures), of Chapter 2, Zoning Districts - Uses and Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as shown on Attachment A. SECTION II. The Maximum Impervious Surface Area section of subsection 4-2-110A, Development Standards for Residential Zoning Designations (Primary and Attached Accessory Structures), of Chapter 2, Zoning Districts - Uses and Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as shown on Attachment B. SECTION III. Subsection 4-3-050C.5.d.ii, New or Modified Regional Stormwater Facilities, of Chapter 3, Environmental Regulations and Overlay Districts, of Title IV ORDINANCE NO. 5526 (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as shown on Attachment C. SECTION IV. Subsection 4-3-050C.7.a.ii, Stormwater Treatment and Flow Control Facilities in Buffer, of Chapter 3, Environmental Regulations and Overlay Districts, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as shown on Attachment D. SECTION V. Subsection 4-3-050C.7.a, Activities in Critical Area Buffers, of Chapter 3, Environmental Regulations and Overlay Districts, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add a new subsection iii, entitled "Stormwater Conveyance in Buffer", to read as shown on Attachment E. SECTION VI. Subsection 4-3-050H.2.d.vi(b), Site Improvements, of Chapter 3, Environmental Regulations and Overlay Districts, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: (b) Site Improvements: (1) For facilities located in Zone 1 of an APA, the owner may be required to pave all currently unpaved areas of their facility that are subject to any vehicular use or storage, use, handling, or production of hazardous materials. (2) For those facilities located in Zone 1 of an APA in which the nature of the business involves the use of hazardous materials outside of fully enclosed structures, the City shall evaluate the existing storm water collection and ORDINANCE NO. 5526 conveyance system, and reserves the right to require the owner to upgrade the system to meet the provisions of RMC 4-6-030E4(f), Special Requirement 6 - Aquifer Protection Area (APA). (3) For those facilities located in Zone 1 of an APA, the City may require the owner to test interior wastewater plumbing and the building side sewer for tightness according to subsection H6a(ii) of this Section, Pipeline Requirements- Zone 1, and reserves the right to require that such wastewater conveyance be repaired or replaced according to subsection H6a(i) of this Section, Pipeline Requirements-Zone 1. SECTION VII. Subsection d of subsection 4-3-110E.5, Standards Within Entire Urban Separator, of Chapter 3, Environmental Regulations and Overlay Districts, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: d. Stormwater management shall comply with the Surface Water Design Manual. SECTION VIM. Subsection 4-4-030B, Adoption by Reference, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: B. ADOPTION BY REFERENCE: The goals, objectives, and policies as set forth in the following documents and related studies or documents are presently in force or as modified from time ORDINANCE NO. 5526 to time are hereby incorporated by reference and shall be considered as if fully set forth herein: Cedar River Master Plan Comprehensive Solid Waste Management Plan Green River Valley Plan Fire Department Master Plan Airport Master Plan Comprehensive Park, Recreation and Open Space Plan Comprehensive Water System Plan Long Range Wastewater Management Plan King County Comprehensive Housing Affordability Strategy (CHAS) Shoreline Master Program King County Solid Waste Management Plan Countywide Planning Policies Six-Year Transportation Improvement Plan Street Arterial Plan Traffic Mitigation Resolution and Fee Parks Mitigation Resolution and Fee Fire Mitigation Resolution and Fee Comprehensive Plan SECTION IX. Subsection 4-4-030C.5, Temporary Erosion Control, of Chapter 4, City- wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. ORDINANCE NO. 5526 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: 5. Temporary Erosion Control: Temporary erosion control must be installed and maintained for the duration of the project. This work must comply with the Surface Water Design Manual and must be approved by the Renton Development Services Division. SECTION X. Subsection 4-4-030C.6, Hydroseeding Required, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: 6. Hydroseeding Required: Within thirty (30) days of completion of grading work, the applicant shall hydroseed or plant an appropriate ground cover over any portion of the site that is graded or cleared of vegetation and where no further construction work will occur within ninety (90) days. Alternative measures such as mulch, sodding, or plastic covering as specified in the Surface Water Design Manual may be proposed between the dates of October 1st and April 30th of each year. The Development Services Division's approval of this work is required prior to final inspection and approval of the permit. SECTION XI. Subsection 4-4-060A, Purpose, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add two new subsections, 5 and 6, to read as follows: ORDINANCE NO. 5526 5. Minimize adverse stormwater impacts generated by the removal of vegetation and alteration of landform in order to comply with the requirements of the National Pollutant Discharge Elimination System (NPDES) Phase II Municipal Stormwater Permit. 6. Protect water quality from the adverse impact associated with erosion and sedimentation in order to comply with the requirements of the National Pollutant Discharge Elimination System (NPDES) Phase II Municipal Stormwater Permit. SECTION XII. Subsection 4-4-060C.4, Hydroseeding Required, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: 4. Hydroseeding Required: Within thirty (30) days of completion of grading work, the applicant shall hydroseed or plant an appropriate ground cover over any portion of the site that is graded or cleared of vegetation and where no further construction work will occur within ninety (90) days. Alternative measures such as mulch, sodding, or plastic covering as specified in the Surface Water Design Manual may be proposed between the dates of October 1st and April 30th of each year. The Development Services Division's approval of this work is required prior to final inspection and approval of the permit. SECTION XIII. Section 4-4-060, Grading, Excavating and Mining Regulations, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of ORDINANCE NO. 5526 Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add a new subsection D, entitled General Erosion and Sediment Control Standards, to read as shown below. The current subsections D-E shall be re-lettered accordingly. D. GENERAL EROSION AND SEDIMENT CONTROL STANDARDS: 1. Erosion and Sediment Control Required: A person who clears, grades or otherwise disturbs a site shall provide erosion and sediment control that prevents, to the maximum extent practicable, the transport of sediment from the site to drainage facilities, water resources and adjacent properties. Erosion and sediment controls shall be applied as specified by the temporary erosion and sediment control measures and performance criteria and implementation requirements in the Surface Water Design Manual adopted in accordance with RMC 4-6-030. 2. Seasonal Limitations: From October 1 through April 30, which is the seasonal limitation period, clearing and grading shall only be permitted if shown to the satisfaction of the Director that runoff leaving the construction site will comply with the erosion and sediment control measures and performance criteria and implementation requirements in the Surface Water Design Manual through a combination of the following: a. Site conditions including vegetative coverage, slope, soil type and proximity to receiving waters; and ORDINANCE NO. 5526 b. Proposed limitations on activities and the extent of disturbed areas; and c. Proposed erosion and sedimentation control measures. 3. Expansion or Restriction of Seasonal Limitations: Based on the information provided under subsection Dl of this section, the Administrator or designee may expand or restrict the seasonal limitations on site disturbance. The Administrator or designee shall set forth in writing the basis for approval or denial of clearing or grading during the seasonal limitation period. 4. Approved Erosion and Sediment Control Plan Required: During the seasonal limitation period, clearing and grading will be allowed only if there is installation and maintenance of an erosion and sedimentation control plan approved by the City of Renton Development Services Division that defines any limits on clearing and grading or specific erosion and sediment control measures required during the seasonal limitation period. The Development Services Division may require or approve alternate best management practices. 5. Violation: If, during the course of construction activity or soil disturbance during the seasonal limitation period, silt-laden runoff violating standards in the Surface Water Design Manual leaves the construction site or if clearing and grading limits or erosion and sediment control measures shown in the approved plan are not maintained, the department inspector shall have the responsibility and authority to issue a partial or total stop work order. ORDINANCE NO. 5526 6. Continued Violation: If the erosion and sediment control problem defined in the stop work order is not adequately repaired within twenty-four (24) hours of issuance, then a notice and order may be issued to install adequate erosion and sediment control measures to stop silt-laden runoff from leaving the site. The order may also require the property owner to discontinue any further clearing or grading, except for erosion and sediment control maintenance and repair, until the following April 30. SECTION XIV. Subsection 4-4-060E, Inspection, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby re-lettered as subsection F pursuant to Section X of this ordinance, and amended to read as follows: F. INSPECTION: 1. Inspection Authorized: All operations regulated by this Section shall be subject to inspection by authorized Development Services Division inspection personnel. When extraordinary or special problems or conditions are involved, extra inspection of grading operations and special tests may be ordered by the City. 2. Entry to be Permitted: No owner or occupant or any other person having charge, care or control of any building, land, structure, premises or portion thereof shall fail or neglect, after proper demand, to promptly permit lawful entry thereon by the Development Services Division inspection personnel for the purpose of inspection and examination pursuant to this Section. ORDINANCE NO. 5526 SECTION XV. Section 4-4-060, Grading, Excavating and Mining Regulations, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add a new subsection G, entitled Restoration of Hazard Required, to read as shown below. The current subsections G-S shall be re-lettered accordingly. G. RESTORATION OF HAZARD REQUIRED: Whenever the Administrator or designee determines that an existing site, as a result of clearing or grading, excavation, embankment, or fill has become a hazard to life and limb, or endangers property, or adversely affects the safety, use or stability of a public way or drainage channel, the owner of the property upon which the clearing, grading, excavation or fill is located, or other person or agent in control of said property, upon receipt of notice in writing from the Administrator or designee, shall within the period specified therein restore the site affected by such clearing or grading or repair or eliminate such excavation or embankment or fill so as to eliminate the hazard and be in conformance with the requirements of this chapter. SECTION XVI. Subsection 4-4-060Q, Permits and Fees, of Chapter 4, City-wide Property Development Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby re-lettered as subsection S pursuant to Section XII of this ordinance, and amended to change the title to "Permits and Fees Required" and to read as follows: 10 ORDINANCE NO. 5526 S. PERMITS AND FEES REQUIRED: 1. Submittal Requirements and Fees: Grading, excavation and mining permits and licenses are required per RMC 4-9-080 for major and minor activities. Submittal requirements are listed in RMC 4-8-120, Submittal Requirements - Specific to Application Type. Application fees are listed per Chapter 4-1 RMC, Administration and Enforcement. 2. Threshold for Drainage Review: A person applying for a grading, excavation and mining permit and license shall be required to comply with all drainage review requirements per RMC chapter 4-6-030 if the project results in seven thousand (7,000) square feet or more of land disturbing activity. 3. Plans and Calculations Required: Submittal of plans and supportive calculations shall be in accordance with RMC 4-6-030. SECTION XVII. Section 4-6-030, Drainage (Surface Water) Standards, of Chapter 6, Street and Utility Standards, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to read as follows: 4-6-030 DRAINAGE (SURFACE WATER) STANDARDS: A. PURPOSE: 1. The purpose of this Section shall be to promote and develop policies with respect to the City's watercourses and to preserve them by minimizing water quality degradation by previous siltation, sedimentation and pollution of creeks, streams, rivers, lakes and other bodies of water, and to protect property owners 11 ORDINANCE NO. 5526 tributary to developed and undeveloped land from increased runoff rates and to ensure the safety of roads and rights-of-way. 2. It shall also be the purpose of this Section to reduce flooding, erosion, and sedimentation; prevent and mitigate habitat loss; enhance groundwater recharge; and prevent water quality degradation through permit review, construction inspection, enforcement, and maintenance in order to promote the effectiveness of the requirements. 3. It shall also be a purpose of this Section to regulate the Municipal Separate Storm Sewer System (MS4) regarding the contribution of pollutants, consisting of any material other than stormwater, including but not limited to illicit discharges, illicit connections and/or dumping into any storm drain system, including surface and/or groundwater throughout the City that would adversely impact surface and groundwater quality of the City and the State of Washington, in order to comply with requirements of the National Pollutants Discharge Elimination System (NPDES) Phase II Municipal Stormwater Permit. B. ADMINISTERING AND ENFORCING AUTHORITY: The Administrator of the Public Works Department is responsible for the general administration and coordination of this Section. All provisions of this Section shall be enforced by the Administrator or his or her designated representatives. 12 ORDINANCE NO. 5526 C. ADOPTION OF SURFACE WATER DESIGN MANUAL: The 2009 King County Surface Water Design Manual (KCSWDM), as now or as hereafter may be amended by King County or the City of Renton, and hereby referred to as the Surface Water Design Manual, is hereby adopted by reference, with the exception of Chapters 1 and 2 of the King County Surface Water Design Manual which are not adopted. Chapters 1 and 2 of the Surface Water Design Manual, as amended by the City of Renton to specify local requirements and procedures, are hereby adopted by reference. References 1, 2, 3, 4A, 4B, 4D, 7B, 7C, 8F, 8G, 9 and 10 of the King County Surface Water Design Manual are not adopted. One copy of the Surface Water Design Manual shall be filed with the City Clerk including any amendments thereto. D. WHEN REQUIRED: All persons applying for any of the following permits and/or approvals shall submit for approval a drainage plan with their application and/or request: 1. Mining, excavation or grading permit or license; 2. Shoreline permit; 3. Flood control zone permit; 4. Subdivision; 5. Short plat; 6. Special permit; 7. Temporary permit when involving land disturbance; 8. Building Permit; 13 ORDINANCE NO. 5526 9. Planned urban development; 10. Site plan approval; 11. Construction Permit; 12. Stormwater Permit; 13. Binding Site Plan; 14. Any other development or permit application which will affect the drainage in any way. The plan submitted during one permit approval process may be subsequently submitted with further required applications. The plan shall be supplemented with additional information at the request of the Public Works Department. E. DRAINAGE REVIEW: 1. When Required: A drainage review is required when any proposed project is subject to a City of Renton permit or approval as determined under Subsection D of this Section and: a. Would result in two thousand (2,000) square feet or more of new impervious surface, replace impervious surface or new plus replaced impervious surface; or b. Would involve seven thousand (7,000) square feet of land disturbing activity; or c. Would construct or modify a drainage pipe or ditch that is twelve inches (12") or more in size or depth or receives surface or stormwater runoff 14 ORDINANCE NO. 5526 from a drainage pipe or ditch that is twelve inches (12") or more in size or depth; or d. Contains or is adjacent to a critical area designation, defined and regulated in RMC 4-3-050. 2. Scope of Review: The drainage review for any proposed project shall be scaled to the scope of the project's size, type of development and potential for impacts to the regional surface water system to facilitate preparation and review of project applications. If drainage review for a proposed project is required under Subsection E of this Section, the Renton Development Services Division shall determine which of the following drainage reviews apply as specified in the Surface Water Design Manual: a. Small project drainage review; b. Targeted drainage review; c. Full drainage review; d. Large project drainage review. 3. Core Requirements: A proposed project required to have drainage review by Subsection El of this Section must meet each of the following core requirements which are described in detail in the Surface Water Design Manual. Projects subject only to small project drainage review that meet the small project drainage requirements specified in the Surface Water Design Manual, including flow control best management practices, erosion and sediment control 15 ORDINANCE NO. 5526 measures, and drainage plan submittal requirements are deemed to comply with the following core requirements: a. Core requirement 1 - Discharge at the natural location: All surface and storm water runoff from a project shall be discharged at the natural location so as not to be diverted onto, or away from, downstream properties. The manner in which runoff is discharged from the project site shall not create a significant adverse impact to downhill properties or drainage systems as specified in the discharge requirements of the Surface Water Design Manual. b. Core requirement 2 - Offsite analysis: The initial application submittal for proposed projects shall include an offsite analysis report that assesses potential offsite drainage impacts associated with development of the proposed site and proposes appropriate mitigations to those impacts. This initial submittal shall include, at minimum, a Level One downstream analysis as described in the Surface Water Design Manual. If impacts are identified, the proposed projects shall meet any applicable problem-specific requirements as specified in the Surface Water Design Manual. c. Core Requirement 3 - Flow control: Proposed projects including redevelopment projects that would result in two thousand (2,000) square feet or more of new plus replaced impervious surface or thirty-five thousand (35,000) square feet or more of new pervious surface, shall provide flow control facilities or flow control BMPs, or both, to control surface and storm water runoff generated by new impervious surface, new pervious surface, and replaced 16 ORDINANCE NO. 5526 impervious surface, as specified in the Surface Water Design Manual. Flow control facilities shall meet the area-specific flow control facility requirements and in accordance with the applicable flow control facility implementation requirements as specified in the Surface Water Design Manual. Flow control BMPs shall also be applied as specified in the Surface Water Design Manual. Projects subject to area-specific flow control facility requirements as shown in Reference 11-A of the Surface Water Design Manual shall meet one of the following flow control facility performance criteria as directed in the Surface Water Design Manual: i. Peak Rate Flow Control Standard: Shall match the predeveloped site's peak discharge rates for the two year, ten year and one hundred year return periods assuming existing site conditions as the predeveloped site condition; ii. Flow Control Duration Standard (for existing site conditions): Shall match the predeveloped site's discharge duration for the discharge rates between fifty percent (50%) of the two year peak flow through the fifty year peak flow and the two and ten year peak discharge assuming existing site conditions as the predeveloped site condition; iii. Flow Control Duration Standard (for forested site conditions): Shall match the predeveloped site's discharge duration for the discharge rates between fifty percent (50%) of the two year peak flow through the fifty year 17 ORDINANCE NO. 5526 peak flow and the two and ten year peak discharge assuming forested site conditions as the predeveloped site condition. iv. Flood Problem Flow Control Standard: Shall meet the flow control duration standard in number iii above and also match the predeveloped site's discharge rate for the hundred-year return period. d. Core requirement 4 - Conveyance system: All engineered conveyance system elements for proposed projects shall be analyzed, designed and constructed to provide the minimum level of protection against overtopping, flooding, erosion and structural failure as specified by the conveyance requirements for new and existing systems and conveyance implementation requirements described in the Surface Water Design Manual. e. Core requirement 5 - Erosion and sediment control: All proposed projects that will clear, grade or otherwise disturb the site shall provide erosion and sediment control that prevents, to the maximum extent practicable, the transport of sediment from the site to drainage facilities, water resources and adjacent properties. Erosion and sediment controls shall be applied in accordance with RMC 4-4-060 and RMC 4-4-130 as specified by the temporary erosion and sediment control measures and performance criteria and implementation requirements in the Surface Water Design Manual. f. Core requirement 6 - Maintenance and operation: Maintenance of all drainage facilities in compliance with City of Renton Maintenance Standards is 18 ORDINANCE NO. 5526 the responsibility of property owner as described in the Surface Water Design Manual. g. Core requirement 7 - Financial guarantees and liability: All drainage facilities constructed or modified for projects, except downspout infiltration and dispersion systems for single family residential lots, must comply with the liability requirements of RMC 4-6-030M. h. Core requirement 8 - Water quality: Proposed projects that would result in five thousand (5,000) square feet or more of new pollution generating impervious surface or thirty-five thousand (35,000) square feet or more of new pollution-generating pervious surface, or that are redevelopment projects that would result in a total of five thousand (5,000) square feet or more of new and replaced pollution-generating impervious surface, shall provide water quality treatment facilities to treat polluted surface and storm water runoff generated by new or replaced pollution-generating impervious surface, as specified in the Surface Water Design Manual. Water quality treatment facilities shall meet the land-use water quality treatment requirements and the water quality implementation requirements applicable to the project site as specified in the Surface Water Design Manual. The facilities specified by these requirements are designed to reduce pollutant loads according to the applicable annual average performance goals listed in Subsections h.i and h.ii of this Section for ninety-five percent (95%) of the annual average runoff volume: 19 ORDINANCE NO. 5526 i. for basic water quality: remove eighty percent (80%) of the total suspended solids; ii. for enhanced basic water quality: remove fifty percent (50%) of the total zinc. 4. Special Requirements: A proposed project required by Subsection E of this Section to have drainage review shall meet any of the following special requirements which apply to the site and which are described in detail in the Surface Water Design Manual. The City of Renton Development Services Division shall verify if a proposed project is subject to and must meet any of the following special requirements: a. Special Requirement 1 - Other area specific requirements: The Surface Water Utility may apply a more restrictive requirement for controlling drainage on an area-specific basis. Other adopted area-specific regulations may include requirements that have a direct bearing on the drainage design of a proposed project. b. Special Requirement 2 - Flood hazard delineation: If a proposed project contains or is adjacent to a stream, lake, wetland or closed depression, or if other City regulations require study of flood hazards relating to the proposed project, the one hundred year floodplain boundaries and floodway shall be determined and delineated on the site improvement plans and profiles and any final maps prepared for the proposed project. The flood hazard study shall be prepared for as specified in the Surface Water Design Manual. 20 ORDINANCE NO. 5526 c. Special Requirement 3 - Flood protection facilities: If a proposed project contains or is adjacent to a stream that has an existing flood protection facility, such as a levee, revetment or berm, or proposes to either construct a new or modify an existing flood protection facility, then the flood protection facilities shall be analyzed and designed as specified in the Surface Water Design Manual to conform with the Federal Emergency Management Agency regulations as found in 44 C.F.R. d. Special Requirement 4: All commercial, industrial and multifamily projects (irrespective of size) undergoing drainage review are required to implement applicable source control in accordance with the King County Stormwater Pollution Prevention Manual and the Surface Water Design Manual. e. Special Requirement 5 - Oil control: If a proposed project is a high- use site, then oil control shall be applied to all runoff from the high-use portion of the site as specified in the Surface Water Design Manual. f. Special Requirement 6 - Aquifer Protection Area (APA): If a proposed project is located within the APA as identified in RMC 4-3-050, then the project must comply with drainage requirements in the Surface Water Design Manual and RMC 4-3-050. F. REQUIREMENTS FOR DRAINAGE REVIEW: All persons applying for drainage review as specified in Subsection El of this Section shall submit to the Development Services Division all engineering plans for review in accordance with the Surface Water Design Manual. The drainage 21 ORDINANCE NO. 5526 plan and supportive calculation report(s) shall be stamped by a professional civil engineer registered and licensed in the State of Washington. G. ADOPTION OF STORMWATER POLLUTION PREVENTION MANUAL (SPPM): The 2009 King County Stormwater Pollution Prevention Manual (SPPM), as now or as hereafter may be amended by King County or the City of Renton, and hereby referred to as the Stormwater Pollution Prevention Manual, is hereby adopted by reference. One copy of the manual shall be filed with the City Clerk including any amendments thereto. H. DISCHARGE PROHIBITION: 1. Prohibition of Illicit Discharge: Materials, whether or not solids or liquids, other than surface water and stormwater shall not be spilled, leaked, emitted, discharged, disposed or allowed to escape into the storm sewer and/or drain system, surface water, groundwater, or watercourses. a. Examples of illicit discharge include but are not limited to the following: i. Trash, debris or garbage; ii. Construction materials or wastewater; iii. Petroleum products, including but not limited to oil, gasoline, greases, fuel oil or heating oil; iv. Antifreeze, brake fluid, windshield cleaner and other automotive products; 22 ORDINANCE NO. 5526 v. Metals in either particulate or dissolved form; vi. Flammable or explosive materials or substances; vii. Radioactive materials; viii. Acids or batteries of any kind; ix. Alkalis or bases; x. Paints, stains, resins, lacquers, or varnishes; xi. Degreasers, solvents or chemicals used in laundries or dry cleaners; xii. Drain cleaners; xiii. Pesticides, herbicides and fertilizers; xiv. Steam cleaning wastes; xv. Soaps, detergents, ammonias; xvi. Swimming pool and spa cleaning wastewater and filter backwash containing water disinfectants (chlorine, bromine, or other chemicals); xvii. Heated water; xviii. Domestic animal waste; xix. Sewage; xx. Recreational vehicle wastewater or sewage; xxi. Animal carcasses; xxii. Food waste; xxiii. Bark and other fibrous material; 23 ORDINANCE NO. 5526 xxiv. Collected lawn clippings, leaves, branches or other yard waste material; xxv. Silt, sediment or gravel; xxvi. Dyes; xxvii. Chemicals not normally found in uncontaminated water; xxviii. Wastewater or process water (including filtered or purified); xxix. Any pollution or contaminant as referenced in the Stormwater Pollution Prevention Manual; and xxx. Any hazardous material as defined in RMC 4-11-080, or waste not listed above and any other process-associated discharge except as otherwise allowed in this Section. b. The following are examples of allowed discharges by this Section if the discharges do not contain pollutants and unless the Administrator evaluates and determines that they are causing an adverse impact: i. Diverted stream flows; ii. Spring water; iii. Rising groundwater; iv. Uncontaminated groundwater infiltration; v. Uncontaminated pumped groundwater; vi. Foundation or footing drains; vii. Water from crawl space pumps; viii. Air conditioning condensation; 24 ORDINANCE NO. 5526 ix. Flows from riparian habitat and wetland; x. Discharges from emergency fire fighting activities; xi. Discharges specified in writing by the authorized enforcement agency as being necessary to protect public health and safety; xii. Irrigation water from an agricultural source that is commingled with stormwater runoff; xiii. Storm system dye testing is allowable by the City, and any dye testing by others requires verbal notification to the Public Works Department at least one day prior to the date of the test. c. Activities that may result in illicit discharge, unless the application of Best Management Practices (BMPs) as specified in the Stormwater Pollution Prevention Manual are utilized, include but are not limited to: i. Discharges from potable water sources, including water line flushing, hyperchlorinated water line flushing, fire hydrant system flushing, and pipeline hydrostatic test water. Planned discharges shall be dechlorinated to a concentration of 0.1 ppm or less, pH-adjusted, if necessary, and volumetrically and velocity controlled to prevent resuspension of sediments into the MS4; ii. Discharges from lawn watering and other irrigation runoff. These shall be minimized through, at a minimum, public education activities and water conservation efforts; iii. Dust control with potable water; iv. Automotive, airplane and boat washing; 25 ORDINANCE NO. 5526 v. Pavement and building washing; vi. Dechlorinated swimming pool discharges. The discharges shall be dechlorinated to a concentration of 0.1 ppm or less, pH-adjusted and reoxygenized if necessary, volumetrically and velocity controlled to prevent resuspension of sediments in the MS4; vii. Auto repair and maintenance; viii. Building repair and maintenance; ix. Landscape maintenance; x. Hazardous waste handling; xi. Solid and food waste handling; xii. Application of pesticides; xiii.Non-stormwater discharge permitted under another NPDES permit; provided that the discharge is in full compliance with all requirements of the permit, waiver, or other applicable requirements and regulations, d. A person does not violate this subsection G if: i. That person has properly designed, constructed, implemented and is maintaining BMPs as required by this Chapter and Section, but contaminants continue to enter surface and stormwater and underground water; ii. That person can demonstrate that there are no additional contaminants in discharges from the site above the background conditions of water entering the site; 26 ORDINANCE NO. 5526 iii. The discharge is a result of an emergency response activity or other action that must be undertaken immediately or within a time too short to allow full compliance with this Chapter or Section in order to avoid an imminent threat to public health or safety. The Administrator by public rule may specify actions that qualify for this exemption in City procedures. A person undertaking emergency response activities shall take steps to assure that the discharges resulting from such activities are minimized. In addition, this person shall evaluate BMPs to restrict recurrence. e. Any person who knowingly allows or permits any prohibited discharges, as set forth in this subsection G or the Stormwater Pollution Prevention Manual, through illicit connections, dumping, spills, improper maintenance of BMPs or other discharges, that allow contaminants to enter surface and stormwater or groundwater, shall be in violation of this Section. 2. Prohibition of Illicit Connections: The construction, use, maintenance or continued existence of any connection identified by the Administrator or designee, that may convey any pollution or contaminants or anything not composed entirely of surface water and stormwater, directly into the MS4, is prohibited, including without limitation, existing illicit connections regardless of whether the connection was permissible under law or practices applicable or prevailing at the time of connection. 3. Remedy: 27 ORDINANCE NO. 5526 a. The person and/or property owner responsible for an illicit connection and/or illicit discharge shall initiate and complete all actions necessary to remedy the effects of such connection or discharge at no cost to the City. b. If the person responsible for an illicit connection or illicit discharge and/or the owner of the property on which the illicit connection or illicit discharge has occurred fails to address the illicit connection or illicit discharge in a timely manner, the Administrator or designee shall have the authority to implement removal or remedial actions following lawful entry upon the property. Such actions may include, but not be limited to: installation of monitoring wells; collection and laboratory testing of water, soil, and waste samples; cleanup and disposal of the illicit discharge, and remediation of soil and/or groundwater. The property owner and/or other person responsible for the release of an illicit discharge shall be responsible for any costs incurred by the Public Works Department or its authorized agents in the conduct of such remedial actions and shall be responsible for City expenses incurred due to the illicit connection or illicit discharge, including but not limited to removal and/or remedial actions in accordance with RMC 1-3-3. c. Compliance with this subsection G shall be achieved through the implementation and maintenance of best management practices (BMPs) described in the Stormwater Pollution Prevention Manual. The Administrator or designee shall initially rely on education and informational assistance to gain 28 ORDINANCE NO. 5526 compliance with this subsection G, unless the Administrator or designee determines a violation poses a hazard to public health, safety, or welfare, endangers any property and/or other property owned or maintained by the City, and therefore should be addressed through immediate penalties. The Administrator or designee may demand immediate cessation of illicit discharges and assess penalties for violations that are an imminent or substantial danger to the health or welfare of persons or danger to the environment. 4. Elimination of Illicit Connection and/or Illicit Discharge: a. Notice of Violation: Whenever the Administrator or designee finds that a person has violated a prohibition or failed to meet a requirement of this Section, he or she may order compliance by written notice of violation to the property owner and/or responsible person, by first class and certified mail with return receipt requested. Such notice may require without limitation: i. The performance of monitoring, analyses, and reporting by the violator; ii. The elimination of illicit connections or discharges; iii. That violating discharges, practices, or operations shall immediately cease and desist; iv. The abatement or remediation of stormwater pollution or contamination hazards and the restoration of any affected property; and v. The implementation of source control or treatment BMPs. Any person responsible for a property or premises which is, or may be, the source of 29 ORDINANCE NO. 5526 an illicit discharge, may be required to implement, at said person's expense, additional structural and nonstructural BMPs to prevent the further discharge of pollutants to the municipal separate storm sewer system and/or waters of the State. These BMPs shall be part of a stormwater pollution prevention plan (SWPP) as necessary for compliance with requirements of the NPDES permit. b. Requirement to Eliminate Illicit Connection: The Administrator or designee shall send a written notice, sent by first class and certified mail with return receipt requested to the property owner and/or the person responsible for the illicit connection, informing the property owner or person responsible for an illicit connection to the MS4 that the connection must be terminated by a specified date. c. Requirement to Eliminate Illicit Discharges: The Administrator or designee shall send a written notice, sent by first class and certified mail with return receipt requested to the property owner and/or the person responsible for the illicit discharge, informing the property owner or person responsible for an illicit discharge to the MS4, whether it be surface water and/or groundwater, that the discharge must be terminated by a specified date. d. Sample and Analysis: When the Administrator or designee has reason to believe that an illicit connection is resulting in an illicit discharge, the Administrator or designee may sample and analyze the discharge and recover the cost of such sampling and analysis from the property owner or person responsible for such illicit connection or discharge pursuant to RMC 1-3-3, as 30 ORDINANCE NO. 5526 now or as hereafter may be amended, and require the person permitting or maintaining the illicit connection and/or discharge to conduct ongoing monitoring at that person's expense. e. Right of Appeal from Administrative Decision: Any person aggrieved by an administrative decision of the Administrator or designee, may appeal such decision pursuant to RMC 4-8-110. f. Any illicit connection and/or illicit discharge as set forth in this Section or the Stormwater Pollution Prevention Manual is hereby declared to be a nuisance pursuant to RMC 1-3-3, and as defined in RMC l-3-4A.ll.c(23). 5. Reporting Requirements: a. In the event of an illicit discharge or spill of hazardous material into the stormwater drainage system or waters of the City, State of Washington or United States, said person with knowledge thereof shall immediately notify the emergency dispatch services (911). b. In the event of an illicit discharge of nonhazardous material into the stormwater drainage system or waters of the City, State of Washington or United States, said person with knowledge thereof shall immediately notify the Public Works Department by phone at 425-430-7400, or in person. 6. Inspections, Investigation and Sampling: The Administrator or designee may lawfully enter property to inspect the facilities of any person to determine compliance with the requirements of these regulations. a. Access: 31 ORDINANCE NO. 5526 i. The Administrator or shall be permitted to lawfully enter and inspect sites subject to regulation under this Chapter and Section as often as may be necessary to determine compliance herewith, at all reasonable hours for the purpose of inspections, sampling or records examination. ii. The Administrator or designee shall have the right to set up on the property necessary devices to conduct sampling, inspection, compliance monitoring, and/or metering actions. b. Compliance with Inspection Report: Within thirty (30) days of receiving an inspection report from the Public Works Department, the property owner or operator shall file with the Department a plan and time schedule to implement any required modifications to the site or to the monitoring plan needed to achieve compliance with the intent of this Chapter or Section or the NPDES permit conditions. This plan and time schedule shall also implement all of the recommendations of the Department. 7. All persons subject to the provisions of this Section shall retain and preserve for no less than three (3) years any records, books, documents, memoranda, reports, correspondence, and any and all summaries thereof, relating to operation, maintenance, monitoring, sampling, remedial actions and chemical analysis made by or on behalf of a person in connection with any illicit connection or illicit discharge. All records which pertain to matters which are the subject of administrative or any other enforcement or litigation activities brought by the City pursuant to this Code shall be retained and preserved by the 32 ORDINANCE NO. 5526 person until all enforcement activities have concluded and all periods of limitation with respect to any and all appeals have expired. I. REVIEW AND APPROVAL OF PLAN: 1. Process: All storm drainage plans and supportive calculations shall be prepared in connection with any of the permits and/or approvals listed in Subsection D of this Section shall be submitted for review and approval to the Development Services Division. 2. Fees: Fees shall be as listed in RMC 4-1-180B. 3. Additional Information: The permit application shall be supplemented by any plans, specifications or other information considered pertinent in the judgment of the Administrator or designee. 4. Tests: Whenever there is insufficient evidence of compliance with any of the provisions of this Section or Code, or evidence that any material or construction does not conform to the requirements of this Section or Code, the Administrator or designee may require tests as proof of compliance to be made at no expense to this jurisdiction. Test methods shall be as specified by this Section or Code or by other recognized test standards. If there are no recognized and accepted test methods for the proposed alternate, the Administrator or designee shall determine test procedures. Suitable performance of the method or material may be evidence of compliance meeting the testing requirement. J. BONDS AND LIABILITY INSURANCE REQUIRED: 33 ORDINANCE NO. 5526 The Development Services Division shall require all persons constructing drainage facilities pursuant to RMC 4-6-030, except downspout infiltration and dispersion systems for single family residential lots to post with the City of Renton a surety, cash bonds, assignment of funds or certified check in the amount equal to the estimated cost of construction calculated using the Bond Quantity Worksheet as described in the Surface Water Design Manual. 1. Construction Bond: Prior to commencing construction, the person constructing the drainage facility shall post a construction bond in an amount sufficient to cover the cost of conforming said construction with the approved drainage plans. In lieu of a bond, the applicant may elect to establish a cash escrow account with his bank in an amount deemed by the City of Renton to be sufficient to reimburse the City if it should become necessary for the City to enter the property for the purpose of correcting and/or eliminating hazardous conditions relating to soil stability and/or erosion. The instructions to the escrowee shall specifically provide that after prior written notice unto the owner and his failure to correct and/or eliminate existing or potential hazardous conditions and his failure to timely remedy same, the escrowee shall be authorized without any further notice to the owner or his consent to disburse the necessary funds to the City of Renton for the purpose of correcting and/or eliminating such conditions complained of. After determination by the Department that all facilities are constructed in compliance with the approved plans, the construction bond shall be released. 34 ORDINANCE NO. 5526 2. Maintenance Bond: After satisfactory completion of the facilities and release of the construction bond by the City, the person constructing the facility shall commence a two (2) year period of satisfactory maintenance of the facility. A cash bond, surety bond or bona fide contract for maintenance with a third party for the duration of this two (2) year period, to be approved by the City of Renton and to be used at the discretion of the City of Renton to correct deficiencies in said maintenance affecting public health, safety and welfare, must be posted and maintained throughout the two (2) year maintenance period. The amount of the cash bond or surety bond shall be in the amount equal to 20% of the estimated cost of construction for a two (2) year period calculated using the Bond Quantity worksheet as described in the Surface Water Design Manual. 3. Liability Policy: Before a permit shall be issued for any construction, insurance will be required as follows: a. The applicant shall secure and maintain in force throughout the duration of the permit Commercial General Liability insurance written on an occurrence basis with limits no less than one million dollars ($1,000,000) per occurrence/two million dollars ($2,000,000) aggregate. b. Copies of such insurance policy or policies shall be furnished unto the City with a special endorsement in favor of the City with the City named as a primary and noncontributory additional insured on the insurance policy and an endorsement stating such shall be provided to the City. 35 ORDINANCE NO. 5526 c. The policy shall provide that it will not be canceled or reduced without 30 days^ advanced written notice to the City. d. Upon showing of a hardship and at the discretion of the Administrator or designee, the insurance requirements may be reduced or waived for single-family or two-family residential applications. K. CITY ASSUMPTION OF MAINTENANCE: 1. Maintenance of Facilities by City Authorized: The City of Renton is authorized to assume the maintenance of flow control and water quality treatment facilities after the expiration of the two (2) year maintenance period in connection with the subdivision of land if: a. All of the requirements of Subsection E of this Section have been fully complied with; b. The facilities have been inspected and any defects or repairs have been corrected and approved by the Department prior to the end of the two (2) year maintenance period; c. All necessary easements entitling the City to properly maintain the facility have been conveyed to the City; and d. It is recommended by the Administrator and concurred in by the City Council that said assumption of maintenance would be in the best interests of the City. 2. Notification of Defect Required: The owner of said property shall throughout the maintenance period notify the City in writing if any defect or 36 ORDINANCE NO. 5526 improper working of the drainage system has come to his or her notice. Failure to so notify the City shall give the City cause to reject assumption of the maintenance of the facility at the expiration of the two (2) year maintenance period, or within one year of the discovery of the defect or improper working of the drainage system, whichever period is the latest in time. 3. Conveyance systems to be maintained and operated by the City must be located in a drainage easement, tract, or right-of-way granted to City. Offsite areas that naturally drain onto the project site must be intercepted at the natural drainage course within the project site and conveyed in a separate conveyance system and must bypass onsite stormwater facilities. Separate conveyance systems that intercept offsite runoff and are located on private property must be located in a drainage easement that may be dedicated to the City if the City deems it appropriate depending on the upstream tributary area. L RETROACTIVITY RELATING TO CITY MAINTENANCE OF SUBDIVISION FACILITIES: If any person constructing drainage facilities pursuant to this Section and/or receiving approval of drainage plans prior to the effective date of the ordinance codified in this Section reassesses the facilities and/or plans so constructed and/or approved and demonstrates, to the Administrator's satisfaction, total compliance with the requirements of this Section, the City may, after inspection, approval and acknowledgment of the proper posting of the required bonds as specified in Subsection M of this Section, assume maintenance of the facilities. 37 ORDINANCE NO. 5526 M. ADJUSTMENT: 1. An adjustment to the requirements contained in this Section or other requirements in the Surface Water Design Manual may be proposed. The resulting development shall be subject to all of the remaining terms and conditions of this section and the adjustment shall: a. Produce a compensating or comparable result in the public interest; and b. Meet the objectives contained in this Section of safety, function, appearance, environmental protection and maintainability based upon sound engineering judgment. 2. Requests for adjustments that may conflict with the requirements of any other City departments shall require review and concurrence with that department. 3. A request for an adjustment shall be processed in accordance with the procedures specified in the Surface Water Design Manual. 4. The applicant may appeal an adjustment decision by following the appeal procedures as specified in the Surface Water Design Manual per RMC 4-8-110. N. VARIANCE: 1. If complying with Subsection E2 will deny all reasonable use of a property, a variance to the requirements in the Surface Water Design Manual may be requested te—from the Community and Economic Development 38 ORDINANCE NO. 5526 Administrator or designee in accordance with the variance process defined in the Surface Water Design Manual and RMC 4-9-250. 2. A request for a variance shall be processed in accordance with RMC 4-9- 250. O. SEVERABILITY: If any provision, subsection, sentence, clause or phrase of this Section or the application thereof to any person or circumstances is held invalid, the remaining portions of this Section and the application of such provisions to other persons or circumstances shall not be affected thereby. P. VIOLATIONS OF THIS SECTION AND PENALTIES: A violation of any of the provisions of this Section shall be a civil infraction upon the first offense pursuant to RMC 1-3-2. See also RMC 4-6-110. SECTION XVIII. Subsection 4-8-120D.4, Definitions D, of Chapter 8, Permits - General and Appeals, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended so the definitions of "Drainage Plan/Map" and "Drainage Report" read as follows: Drainage Plan/Map: Plans drawn to scale and stamped by a State of Washington licensed engineer and complying with the requirements of RMC 4-6- 030, Drainage (Surface Water) Standards, and the Surface Water Design Manual. Drainage Report: A report stamped by a State of Washington licensed engineer complying with the requirements of the City of Renton Drafting 39 ORDINANCE NO. 5526 Standards, RMC 4-6-030, Drainage (Surface Water) Standards, and the Surface Water Design Manual. SECTION XIX. Subsection 4-8-120D.5, Definitions E, of Chapter 8, Permits - General and Appeals, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended so the definition of "Erosion Control Plan, Temporary", reads as follows: Erosion Control Plan, Temporary: Drawings of the entire site showing the proposed erosion control measures for the project in conformance with the City of Renton drafting standards and the Surface Water Design Manual. SECTION XX. Subsection 4-9-250B.1, Authority and Applicability for Administrative Variances, of Chapter 9, Permits - Specific, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add a new subsection d, entitled "Proposals to vary from the Drainage Standards", to read as follows: d. Proposals to vary from the Drainage Standards: If an applicant feels that the application of the regulations in the Surface Water Design Manual would deny all reasonable use of the property, the applicant of a development proposal may apply for a variance. SECTION XXI. Subsection 4-9-250B, Variance Procedures, of Chapter 9, Permits - Specific, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add a new subsection 12, 40 ORDINANCE NO. 5526 entitled "Review Criteria", to read as shown below. The current subsections 12-17 shall be renumbered accordingly. 12. Special Review Criteria: In lieu of the variance criteria of Subsection B6 of this Section, applications proposing to alter the core and special requirements described in the Surface Water Design Manual shall be reviewed for compliance with all of the following criteria: a. There are special physical circumstances or conditions affecting the property such that strict application of the criteria for producing a compensating or comparable result would deprive the applicant of all reasonable use of the parcel of land in question, and every effort has been made to find creative ways to meet the intent of the requirement for which the variance is sought; b. Granting the variance for the individual property in question will not create a significant adverse impact to public health, welfare, water quality, and properties downstream or nearby; c. The variance requires the best practicable alternative for achieving the spirit and intent of the requirement in question; and d. In addition, the application must include the following information as required by the state Department of Ecology per the 2007 Phase II NPDES General Municipal Stormwater Permit: i. The current (pre-project) use of the site. ii. How application of the requirements in the Surface Water Design Manual for which a variance is being requested denies all reasonable use of site 41 ORDINANCE NO. 5526 compared to the development review conditions and restrictions that would have been placed on the project prior to the adoption of the Surface Water Design Manual. iii. The possible remaining uses of the site if the variance was not granted;and iv. The uses of the site that would have been allowed under development review conditions and restrictions that would have been placed on the project prior to the adoption of the Surface Water Design Manual. v. A comparison of the estimated amount and percentage of value loss as a result of the requirements of this manual versus the estimated amount and percentage of value loss as a result of conditions and/or restrictions that would have been placed on the project prior to the adoption of the Surface Water Design Manual. vi. The feasibility for the owner to alter the project to apply the requirements of this manual. SECTION XXII. Section 4-11-190, Definitions S, of Chapter 11, Definitions, of Title IV (Development Regulations) of Ordinance No. 4260 entitled "Code of General Ordinances of the City of Renton, Washington", is hereby amended to add a definition for "Surface Water Design Manual", to read as follows: SURFACE WATER DESIGN MANUAL: Shall be the King County Surface Water Design Manual, as now or as hereafter may be amended by King County, (and supporting documents as appropriate) prepared by King County Department of 42 ORDINANCE NO. 5526 Natural Resources and Parks or its successor organization, and as may be amended, supplemented and modified by the City of Renton Amendments to the King County Surface Water Design Manual that specifies local requirements and procedures describing surface and stormwater design and analysis requirements procedures and guidance. SECTION XXIII. This ordinance shall be effective upon its passage, approval, and five (5) days after publication. PASSED BY THE CITY COUNCIL this lst day of February , 2010. Approved as to form: Lawrence J. Warren, City Attorney Date of Publication: 2/1/2010 ( summary) ORD:1615:l/15/10:scr Bonnie I. Walton, City Clerk APPROVED BY THE MAYOR this lst day of February _, 2010. Denis Law, Mayor 43 ORDINANCE NO. 5526 4-2-110A Development Standards for Residential Zoning Designations (Primary and Attached Accessory Structures) Maximum Building Coverage (Including primary and accessory buildings. Except Accessory Dwelling Units are not counted toward building coverage) RC R-l R-4 and R-8 R-10 and R-14 RM Lots 5 acres or more: 2%. An additional 5% of the total area may be used for agricultural buildings. Lots 10,000 sq ft to 5 acres: 15%. On lots greater than 1 acre, an additional 5% of the total area may be used for agricultural buildings. Lots 10,000 sq ft or less: 35%. 20% Lots greater than 5,000 sq ft: 35% or 2,500 sq ft, whichever is greater. Lots 5,000 sq ft or less: 50% n/a "U" suffix: 75% "T" suffix: 75% "F" suffix: 35% A maximum coverage of 45% may be obtained through the Hearing Examiner site development plan review process. Attachment A ORDINANCE NO. 5526 4-2-110A Development Standards for Residential Zoning Designations (Primary and Attached Accessory Structures) Maximum Impervious Surface Area RC R-l R-4 R-8 Lots 5 acres or more: 20% Lots 10,000 sq ft: 55%. For each additional 10,000 sq ft increase in lot size, the impervious coverage shall be decreased by 1.75% to a minimum of 20% for a 5 acre lot Lots 10,000 sq ft or less: 55% 30% 55% 75% R-10 R-14 RM Detached units: 75% Attached units: 65% 85% "U" and "T" suffixes: 85%. All other suffixes: 75% Attachment B ORDINANCE NO. 5526 4-3-050C.5d.ii. New or Modified Regional Stormwater Facilities is hereby amended to read as follows: ii. New or Modified Regional Stormwater Facilities: Regional stormwater management facilities to be operated and maintained under the direction of the City Surface Water Utility that are proposed and designed consistent with the Washington State Department of Ecology Wetlands and Stormwater Management Guidelines or meeting equivalent objectives. X Attachment C ORDINANCE NO. 5526 4-3-050C.7.ii, Stormwater Treatment and Flow Control Facilities in Buffer, is amended to read as follows: ii. Stormwater Treatment and Flow Control Facilities in Buffer: Stormwater management facilities shall not be built within a critical area buffer except as allowed in Reference 5, Wetlands Protection Guidelines of the City's Surface Water Design Manual and shall require buffer enhancement or buffer averaging when they are sited in areas of forest vegetation, provided the standard buffer zone area associated with the critical area classification is retained pursuant to subsection L or M6c of this Section, and is sited to reduce impacts between the critical area and surrounding activities. Attachment D ORDINANCE NO. 5526 4-3-050C.7.a is amended to add a new subsection iii, to read as follows: iii. Stormwater Conveyance in Buffer: Necessary conveyance systems including stormwater dispersion outfall systems designed to minimize impacts to the buffer and critical area, where the site topography requires their location within the buffer to allow hydraulic function, provided the standard buffer zone area associated with the critical area classification is retained pursuant to subsection L or M6c of this Section, and is sited to reduce impacts between the critical area and surrounding activities. X X X Attachment E