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Home My WebLink AboutTrans 2016-03-21 Item 2A - NPDES - Low Impact Development Code Update�sy City of Tukwila Allan Ekberg, Mayor INFORMATIONAL MEMORANDUM TO: Mayor Ekberg Transportation Committee FROM: Bob Giberson, P.E., Public Works Director BY: Ryan Larson, Senior Program Manager DATE: March 18, 2016 SUBJECT: NPDES Program Project No. 99341210 Low Impact Development Code Update 4951, ISSUE Low Impact Development (LID) code presentation and update. BACKGROUND The City's National Pollutant Discharge Elimination System (NPDES) Phase II permit requires that the City review, revise, and make effective their local development - related codes, rules, standards, or other enforceable documents to incorporate and require LID principles and LID Best Management Practices no later than December 31, 2016. ANALYSIS The City contracted with Otak, Inc. to perform an LID gap analysis and assist the City with LID implementation. Staff will provide a 15 minute presentation on what is low impact development and where the City is on the gap analysis and implementation progress to date. This presentation will inform Council members of the new LID rules required for the Tukwila Municipal Code. FINANCIAL IMPACT The LID Gap Analysis consultant agreement was approved in December 2015 for $59,006, of which $50,000 is funded by a Department of Ecology's Water Quality Stormwater Capacity Grant. INFORMATION ONLY Information only. Attachment: City of Tukwila LID Code Update Presentation W: \PW Eng \ PROJECTS \A- DR Projects \NPDES Program (99341210)\2015 2017 Capacity Grant \Oiak LID Gap Analysis \Info Memo Otak LID Update TC 03 -21 -16 gl.docx 1 City of Tukwila LID Code Update Presentation to Transportation Committee March 21, 2016 Goals for this Update Discuss a process to update Tukwila's development and stormwater codes to remove barriers to Low Impact Development (LID), reduce stormwater runoff through the use of LID site planning practices, and require LID facilities. • What is LID? • Why are we doing this? • How will we achieve it? • What is next? 0 CO What is LID? Low Impact Development is a set of site development principals to minimize impervious surfaces, maintain native vegetation, and manage stormwater runoff close to its source. Examples • Skinny Streets • Parking Area Reduction • Clustering • LID BMPs Sea Street LID, Seattle, WA. Photo courtesy of Washington State Department of Ecology 3 01 Parking Area Reduction & Stormwater Management Parking Tots and roof tops are largest contributors of impervious surface coverage in commercial areas (Schueler, 1995), and a parking lot can require up to 400 sf per vehicle (i.e. 1 acre / 100 cars) (CHI, 2000). Image from Strongtowns.org Image from Inland Paving Asphalt Co, Tri- Cities, WA Image from Elected Official Briefing, by AHBI and Department of Ecology 0 J ro rn LID Best Management Practices (BMPs) The King County Surface Water Design Manual will require LID BMPs such as Bioretention, Permeable Pavements, Dispersion, and Downspout Infiltration on almost all development sites. i -.1 �9 g Residential I , *ti trees 4 cistern driveway with grass center Ir mpost- emended so'BI Ro 1411t 40 i11M161111i rain garden overflow Graphic courtesy City of Seattle Regulatory Framework National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater Permit • Clean Water Act • Washington Department of Ecology • 2013 — 2018 Permit Cycle • Permit Requirement S5.C.4 Integrating LID into Local Codes: A GUIDEBOOK FOR LOCAL GOVERNMENTS Pre; arec L AH6 for he PLger Sound Pa,r erstr,p Firm I JUIY 2012 Revise Development & Stormwater Codes to Require LID • Minimize Impervious Surfaces • Minimize Loss of Native Vegetation • Minimize Stormwater Runoff • Make LID the Common Approach to Site Development PugetSoundPartnersh i p ou %WO,. mmrzwsty, our chn, r. A CO Hydrology Before / After Traditional Development 6 a 6 6 b 8 4 4 4 6 4 4 6 6 6 6 0 6 e a a a a a a preelpita4Ion less evapo- transpiration aporatlon reduce water table rt bedrock groundwater eta all3,0 The Urban Water Cycle Images from Integrating LID into Local Codes, by AH8L and Puget Sound Partnership • Stream discharges increase rapidly and recede quickly • Higher flow velocities = greater erosion and pollutant transport • Peak flow event frequency increases • Groundwater recharge reduced 7 C0 Goal of LID • Urban Landscape More Like Pre - Development Hydrology Example (Less Runoff) Replicating Natural Hydrologic Processes To Manage Stormwater rola Aden, ate stermwater pair%sra tstorms Stotrllwatervautt Y. a serament catchment and-Row spreader to the wet meadow LID Integrated into Redevelopment Trail on Vault LID The terraced floadptoo V0o0os water nuoayheMment tluough altrarwn Inlet and maim-mince chamber to Infdtrxtongallew Infiltration Stream high ilow nd enhance baser Row Rowsd a ree base Row to Miter Creek Upland Meadow viaened itoodplxn wetland removes charnel vxeoon and reConnects stream to ftoo4tarr vwnland Trail/ Boardwalk uwa.re specks and native vegetaton restored Moog t0ll1Cree' INFILTRATION CHAMBERS TRANSITION ZONE \\---1`) here 0 STREAM BUFFER Miller Creek O b 1 ,�taurea•i /.W. STREAM Design for Miller Creek, Burien NERA, Otak, Inc. • Streets • Safety & Convenience • Attractive Places Community Needs City Standards • Street Widths • Parking • Landscaping • Drainage / Stormwater Control 8 • Street Network • Parking Lots • Clearing & Grading • Stormwater Facilities Developer Actions City Development Codes / Standards Guide: • Creation of impervious surfaces • Removal or retention of native vegetation • Location of development • How /where stormwater is managed 1 Completed Landscapes • Buildings • Pavement • Vegetation • Stormwater Where to Look • Title 11: ROW Use • Title 14: Water and Sewers • Title 17: Subdivisions • Title 18: Zoning • Infrastructure Design and Construction Standards • Comprehensive Plan Image from Elected Official Briefing, by AHBL and Department of Ecology 10 TO Topics • Site Planning and Assessment • Healthy Soils • Landscaping and Vegetation • Hard and Impervious Surfaces • Bulk and Dimensions • Clearing and Grading • Streets and Roads • Parking • Design Guidelines and Standards • Stormwater Management and Maintenance • Subdivision and Planned Unit Development • Critical Areas and Shoreline Management Vc_ e2ratJon & tiatAtss Utth AvahlietW , t Site Arce,1 -A,s. Image from Integrating LID into Local Codes, by AHBL and Puget Sound Partnership �.. 0 Update City Codes and Standards 28 Ft Street T x Parking on both sides 24 Ft Street ."a Parking on one sidee Burien 2008 Road Design and Construction Standards rsv,.,..t 13 4/pr. Conventional LID For example: Standard Streets and Commercial Developments Update City Codes and Standards 0 s LID Examples (. 0 Outcomes • Reduce Impervious Surfaces • Encourage Retention of Native Vegetation • Manage Stormwater Close to the Source • Permit Compliance Image by Otak, Inc. City Staff Participants (ublic Works Project Management • Road Standards Use of Right of Way • Engineering Community Development • Site Planning • Parking • Subdivisions • Landscaping Fire Marshal • Street Widths • Landscaping Attorney • Authority • Legal Review Consultant • Code Review • Drafts Ecology requires participation from city officials responsible for setting and enforcing development codes. 0 8 F11=MMA Roadmap 1. Assemble Project Team 2. Review Existing Codes and Standards (Gap Analysis) 3. Understand General LID Topics 4. Amend Existing Codes and Develop New Codes to Fill Gaps 5. Public Review and Adoption Process ( Final Adoption ) 6. Ensure Successful Implementation Deadline December 31, 2016 We are here October 2016 Questions?