6/12/2015 Treating Redevelopment: A Watershed Restoration Tool for - PDF document

6/12/2015 Treating Redevelopment: A Watershed Restoration Tool for Local Governments South Carolina Association of Stormwater Managers Quarterly Meeting Mike MacIntyre, PE June 11, 2015 Key Terms • Development – Land-disturbing activity that creates impervious area or that otherwise decreases the infiltration of precipitation into the soil • Redevelopment – Land-disturbing activity that does not result in a net increase in impervious area and that provides greater or equal stormwater control than the previous development Development Example Existing Building Building Addition 1

6/12/2015 Redevelopment Example Existing Building New Building Key Terms • Detention – Peak Control (flood relief) • The controlled release of the runoff from 10-, 25-, and possibly larger 6-hour storms to prevent flooding of downstream structures and properties – Volume Control (stream erosion prevention) • The slower, controlled release of the runoff from a 1- year, 24-hour storm in order to protect streambanks from being eroded Requirements for Development • Meet each of the following requirements: – Pollutant Removal • Remove pollutants from runoff through filtration, settling or infiltration – Detention • Stream Erosion Protection and Flooding Relief for Storm Drainage Systems, Streets, and Downstream Structures • Hold & slowly release runoff from medium and large rainfall events – Stream Buffer Protection • Expands/complements previous efforts to preserve buffers adjacent to streams – Natural Area Protection • 10% to 25% depending on density of the development (treed area) 2

6/12/2015 Requirements for the Transit Station Areas and the Distressed Business District (Yellow and Green Areas of the Map) • Choose one of the following requirements: – Pollutant Removal • Remove pollutants from runoff through filtration, settling or infiltration – Detention • Stream Erosion Protection and Flooding Relief for Storm Drainage Systems and Streets • Hold & slowly release runoff from medium and large rainfall events – Mitigation Fee • Pay the City a mitigation fee to install water quality enhancement measures within the same watershed • And provide: – Stream Buffer Protection – Peak Detention on Additional Impervious Area Payment of Mitigation Fee – (Nov 2011-Jan 2015) in respect to Transit/Distressed Geography 8 Requirements for Redevelopment (in White Area of the Map) • Choose two of the following requirements: – Pollutant Removal • Remove pollutants from runoff through filtration, settling or infiltration – Detention • Stream Erosion Protection and Flooding Relief for Storm Drainage Systems and Streets • Hold & slowly release runoff from medium and large rainfall events – Mitigation Fee • Pay the City a mitigation fee to install water quality enhancement measures within the same watershed (may be a larger fee if conditions are met) • And provide: – Stream Buffer Protection – Peak Detention on Additional Impervious Area 3

6/12/2015 Mitigation Fee • Set by City Engineer based on City’s cost to design and construct stormwater control measures • Fee has not changed since inception (still many opportunities for cost-effective projects) • As costs of projects increase and large, regional opportunities diminish, fee may increase 10 Fee Structure • Lots less than 1 acre [18-161(a)]- $60,000/impervious acre • Within Transit Station Area/Distressed Business District [18-161(b)]– $60,000/impervious acre • Redevelopment [18-161(c)]-$ 60,000/acre for the first impervious acre, then $90,000/impervious acre for each additional acre • Mitigation fee is prorated for partial acres 11 Fee Structure $600,000 $500,000 $400,000 $300,000 $200,000 $100,000 $0 0 1 2 3 4 5 6 7 Redevelopment Site Size, acres For Example , a 2 acre redevelopment site outside the transit/distressed areas pays a $150,000 fee in lieu of onsite controls 4

6/12/2015 Activity Centers “70% of new multi-family and 75% of new office to be constructed in Activity Centers and Growth Corridors, with emphasis in Growth Corridors on Transit Station Areas.” 13 Mixed Used Activity Centers 14 Payment of Mitigation Fee – (Nov 2011-Jan 2015) in respect to other priority areas 15 5

6/12/2015 Redevelopment Projects paying Fee by Year • How long have the mitigated projects been there? Redevelopment Mitigation Payments Received By Fiscal Year 2012 – 4 projects, 3.49 acres 2013 – 1 project, 1.10 acres 2014 – 2 projects, 5.22 acres 2015 – 5 projects, 5.23 acres 16 Redevelopment Projects Approved Since November 2011 Provided Detention and Paid Fee 6 38% 50% Paid Fee for Redevelopment and Met 8 Development Standards for Increase Paid Fee Only 12% 2 Chart includes 4 redevelopment projects that have not yet been completed/paid the fee 17 Stormwater Control Measures Approved Since November 2011 70 Above Ground Sand Filter 66 63 Underground Detention 60 Above Ground Detention 52 Wet Pond 50 Bioretention 45 Underground Sand Filter 40 Proprietary Device Wetland 30 Infiltration Trench/Pond Permeable Pavement 20 18 15 10 4 3 2 2 0 18 6

6/12/2015 Screening Process to Allow a Fee for Detention 19 Screening Process to Allow a Fee for Detention • Is there an increase of impervious area on the project site? • Are there open stormwater requests for erosion or flooding? • Where does the project drainage area become less than 10% of the total drainage area? • Are there other downstream concerns (e.g. – is there a residential neighborhood that may be negatively impacted)? • Is the local infrastructure adequately sized? • What type of limitations are there on site? 20 Limitations of Redeveloping Sites Redevelopment sites often face substantial challenges accommodating stormwater controls on-site • Difficult topography • Underground utility conflicts • Lack of available space onsite • Brownfield sites • Maintain site operations 21 7

6/12/2015 Why is there a fee in the first place? • Existing paved sites typically have no form of runoff control • Paved surfaces causes runoff that impairs surface waters • Post Construction ordinance requires on-site measures • Redevelopment faces challenges accommodating runoff controls on-site • Caps the compliance cost of affordable housing, redevelopment projects, and increases economic development opportunities 22 Why is there a fee in the first place? • Increases flexibility, and predictability for redevelopment projects • Reduces greenfield development by making redevelopment more affordable • Accelerates watershed recovery by encouraging redevelopment over green field development • The offsite, regional approach recovers watersheds at a faster pace. • Offsite mitigation is an effective strategy in communities nationwide to protect environment while considering costs 23 What Other Local Governments Use Mitigation Fees? • What other municipalities have a mitigation fee? – Atlanta, GA – Austin, TX – Columbus, OH – Orlando, FL – Prince George County, MD – San Antonio, TX – San Francisco, CA – Tampa, FL – Washington, DC 24 8

6/12/2015 Operation and Maintenance • Who maintains stormwater control measures? – Private commercial projects: owner – Multi-family sites: owner – Single-family subdivisions: HOA may petition City to take over maintenance if the measure is in good order two years after it goes into service – Public projects: owner agency 25 Redevelopment Case Study Seven Eleven – N Wendover Rd Pre-Project Conditions (2011) 27 9

6/12/2015 Redevelopment Conditions (2015) 28 Aerial Comparison 2013 Aerial 2014 Aerial 29 Downstream Analysis Open Channel Stormwater Pipe Pipe installed by project. 30 10

6/12/2015 Downstream Analysis – 10% Point Open Channel Stormwater Pipe 31 Site Constraints Tree Save Area Side/Rear Yards and • Setbacks required by Zoning Ordinance Tree Save Areas required • by Tree Ordinance Internal Tree planting • required by Tree Ordinance Underground Stormwater • Control Measure (SCM) required by Post- Construction Stormwater Ordinance (PCSO) 32 Redeveloped Site Specifics Pre-Project (acres) Redevelopment (acres) Tree Save 0 0.24 Additional 0.60 0.07 Vegetated Area Total Pervious 0.60 0.31 Area Impervious Area 0.47 0.76 Site Area 1.07 1.07 33 11

6/12/2015 Stormwater Development Requirements • Provide onsite detention to reduce downstream erosion and flooding impacts. This was accomplished by installing an underground detention system. • Pay mitigation fee for water quality impact at rate of $60,000 per acre of Built Upon Area (BUA). This site paid $44,340. 34 Task Force Questions • Are current stormwater ordinances working to stop degradation? • What are the impacts to the floodplain? 35 How The Current Ordinance Improves the Watershed Through Redevelopment Stream Protection and Flood Reduction Redevelopment Requirements: 4.5 Detention is • provided to slowly 4 release runoff to 3.5 reduce stream 3 erosion 2.5 2 Detention is • 1.5 provided on-site to reduce downstream 1 storm drainage 0.5 system burden 0 Stream Erosion Flow Detention is Storm Drainage • System Flow Street Flooding Flow provided on-site to reduce downstream street flooding Pre-Project Redevelopment 36 12