ANDREW BILLING, P.E., CFM, LEED GREEN ASSOCIATE Lead Stormwater Reviewer CITY OF CHICAGO, DEPARTMENT OF BUILDINGS Andrew Billing, PE, CFM, LEED Green Associate (Mackie Consultants, LLC) is a consultant to the City of Chicago, Department of Buildings. As the Lead Stormwater Reviewer for the City of Chicago since 2008, Andrew manages a small team of consultants who are responsible for the implementation of the City's Stormwater Ordinance. Andrew has more than 24 years of experience in civil engineering in the Chicago area. He received a Bachelor of Science degree from the University of Illinois at Urbana Champaign. Mr. Billing is a licensed Professional Engineer in the State of Illinois, and is also a Certified Floodplain Manager.
City of Chicago Stormwater Management Ordinance The First Eight Years Presented by: Andrew Billing, PE, CFM Mackie Consultants, LLC Consultant to the City of Chicago 2016 November 10, 2016 ASCE Illinois Section Permitting Seminar Why does the City of Chicago require stormwater management? Stormwater Management Ordinance 1
Minimize Basement Flooding Prevent Pollution Stormwater Management Ordinance 2
Protect the source of drinking water Decrease Overland Flooding and Stormwater Impacts Stormwater Management Ordinance 3
Protect Public Safety Improve Sewer Infrastructure Performance Stormwater Management Ordinance 4
Designers must understand Chicago history to design projects in the City of Chicago Chicago River Landscape Courtesy of Chicago Historical Society Stormwater Management Ordinance 5
Rapidly Growing City Courtesy of Chicago Historical Society First Municipal Water Supply System 1853 Stormwater Management Ordinance 6
Combined Sewers 1857 Combined Sewers Drained to the Chicago River Raising Street Elevations to Build Combined Sewers Courtesy Chicago Public Library New street level Clark Street 1857 Old street level Stormwater Management Ordinance 7
Inherent Conflict Need a Solution In 1889 Sanitary District of Chicago (now MWRD) was formed to address: - contamination of the water supply - pollution of the rivers Civil engineers developed a plan to take advantage of a natural watershed divide Stormwater Management Ordinance 8
1900 Chicago River Flow Reversed 1911 North Shore Channel Built 1922 Calumet River Flow Reversed Stormwater Management Ordinance 9
MWRD Interceptors & Treatment Plants 7 Wastewater Treatment Plants Stickney Plant is World s Largest TARP Tunnel and Reservoir Plan aka Deep Tunnel Phase I Tunnel 109.4 miles, 30 d, ~210 ft deep Completed 2006 Phase II Reservoirs O Hare 1996, 350MG McCook 2014, 2024 10BG Thornton 2003, 3.1BG, 2014, 7.9BG Stormwater Management Ordinance 10
Rainblocker Program Stormwater Management Ordinance 11
2016 Stormwater Requirements THREE TIERS 1. Ordinance Effective Jan 1, 2008 (Regulations, Appendix I) 2. Regulations Revised annually by DWM 3. Manual Technical Guide Detailed information on stormwater BMPs Published as two documents www.cityofchicago.org/water click Sewer Regulations Stormwater Management Ordinance A performance based ordinance that: Manages stormwater before it reaches City sewers. Minimizes stormwater flow into the combined sewer system. Improves sewer infrastructure performance. Increases neighborhood green space. Compliments the Landscape Ordinance. Stormwater Management Ordinance 12
Regulated Developments Land disturbance over 15,000 square feet (approximately 4 city lots and larger) At grade impervious areas over 7,500 square feet (approximately 20 space parking lot and larger) Results in discharge of stormwater into any waters or separate sewer system regardless of project size Small Print: Disturbed area shall include 25 percent of the square footage of the critical sidewall of a building that directly connects to the combined sewer system via side gutters or multi-level roofs, and Any average dry-weather flow (based on 1.0 cfs = 43,560 sf) and Detached single family or two family dwellings are excluded. Stormwater Management Plan Provisions Rate control manage peak discharge rate Based upon the capacity of existing sewer or Use City s standard vortex restrictor Volume control manage volume of water discharged Capture the first ½ inch of runoff or Achieve 15% reduction in impervious surface from existing conditions Soil erosion and sediment control Operations and maintenance plan Stormwater Management Ordinance 13
Detention pond Stormwater Management Options Designers are given a wide degree of flexibility in meeting the requirements Cistern Green roof Permeable pavement Underground Detention Filter strip Bioswale Regulated Developments A Closer Look Developments Discharging to Combined Sewers Rate Control Volume Control Proposed Activity Regulated under Stormwater Management Ordinance Required Required 1 Options Available Storage Reduce Imperv. by 15% Residential Development No - - - - Creates, reconstructs or resurfaces atgrade impervious area of less than 7,500 SF No - - - - Creates, reconstructs or resurfaces atgrade impervious area of 7,500 SF or more 3 Disturbs land areas of 15,000 SF or more 3 New roof for vertical building addition (plus sidewall and additional DWF) equivalent to 15,000 SF or more 2 No - - Stormwater Management Ordinance 14
Regulated Developments A Closer Look Developments Discharging to Waters Proposed Activity Regulated under Stormwater Management Ordinance Rate Control Required Required 1 Volume Control Options Available Storage Reduce Imperv. by 15% Residential Development No - - - - Creates, reconstructs or resurfaces atgrade impervious area of less than 7,500 SF No - Creates, reconstructs or resurfaces atgrade impervious area of 7,500 SF or more - Disturbs land areas of 15,000 SF or more - New roof for vertical building addition (plus sidewall and additional DWF) equivalent to 15,000 SF or more 2 No - - Notes: 1. Additional exceptions (airport surfaces, Industrial NPDES permitees) apply (see Ordinance 11-18-040) 2. Only requires delay or decrease in peak discharge from the roof. 3. Only if site is >15% impervious. Rate Control Calculation Methodology Sites < 20 acres Modified Rational Method Spreadsheet Tool provided by the City (Available on DWM Website) Sites >= 20 acres Hydrograph Method TR-20 for example Design Storm Typical Site 100-yr storm (Bulletin 70) Lot-to-lot building (85% lot coverage) 10-yr storm for building, 100-yr storm for remainder of site Detention systems receiving off-site flow check 25-yr storm Stormwater Management Ordinance 15
Rate Control Release Rate Two Options: Standard Maximum Release Rate Computed Maximum Release Rate Rate Control Release Rate Standard Maximum Release Rate For sites < 1.75 acres Use City s standard vortex restrictor 3-inch vortex restrictor nominal 0.15 cfs release regardless of head For sites < 0.75 acres 4-inch vortex restrictor nominal 0.25 cfs release regardless of head For sites >= 0.75 acres Stormwater Management Ordinance 16
Rate Control Standard Maximum Release Rate 1.0 0.9 7500, 0.87 0.8 0.7 3" Vortex Restrictor (0.15 cfs) 4" Vortex Restrictor (0.25 cfs) Site Release Rate (cfs/ac) 0.6 10890, 0.60 0.5 0.4 0.3 0.2 0.1 Legend Regulated Rate for Storage Actual Rate of Discharge 21780, 0.30 43560, 0.25 54450, 0.2 65340, 0.17 0.0 0 10890 sf/ 0.25 ac 21780 sf/ 0.50 ac 32670 sf/ 0.75 ac 43560 sf/ 1.0 ac 54450 sf/ 1.25 sf 65340 sf/ 1.5 ac 76230 sf/ 1.75 ac Size of Site (sf/ac) City of Chicago Standard Vortex Restrictor swirl chamber stem inserted into 8-inch pipe Vortex Restrictor Installed in CB w/ half-trap opening down Vortex Restrictor Installed in CB w/out half-trap Stormwater Management Ordinance 17
Rate Control Release Rate Computed Maximum Release Rate Required for sites > 1.75 acres Allowed for sites <= 1.75 acres Involves a brief study to establish the capacity of the local sewer system Requires Sewer Atlas & Drain Atlas sheets Calculations must be submitted for review Rate Control Release Rate Computed Maximum Release Rate The Lesser of: Outlet sewer capacity Critical local sewer capacity Stormwater Management Ordinance 18
Rate Control Release Rate Outlet Sewer Capacity Maps www.cityofchicago.org/water click Sewer Regulations Rate Control Critical Local Sewer Capacity Release Rate Sewer Segment 2 Area=34.1 (continues on additional sheets) Sewer Segment 1 Area=20.7 Analyze each sewer segment 3.5 ft dia. and smaller Local Sewer Capacity = Q / A (cfs/ac) Where: Q = flowing full capacity of the sewer (cfs) A = area tributary to the sewer (acres) Sewer Segment 3 Area=11.7 Sewer Segment 5 Area=7.22 Sewer Segment 4 Drainage Basin Boundary Sewer Segment 1 Area=2.1 Area=9.81 Stormwater Management Ordinance 19
Rate Control Release Rate Critical Local Sewer Capacity Spreadsheet Tool Tab 0.0 Release Rate Rate Control Release Rate Critical Local Sewer Capacity Spreadsheet Tool Tab 0.0 Release Rate Stormwater Management Ordinance 20
Plate Restrictor Plate Restrictor Installed in CB w/ half-trap Plate Restrictor Installed in CB w/out half-trap Rate Control Detention Systems Options for Providing Detention Storage: Detention Basins Parking Lot Ponding 10 to 12 inch max. depth Aggregate void spaces under infiltration BMP Oversized Pipes RCP allowed other materials might be allowed on a case-by-case basis Detention Vaults Vaults under buildings have special requirements Rooftop Detention Stormwater Management Ordinance 21
Rate Control Unusual Cases Sidewall Area 25% of the area of the largest sidewall of a building that is directly connected to the sewer system through side gutters or multi-level roofs Adds to site area but does not factor into release rate calculation Usually only significant on high rise buildings Rate Control Unusual Cases Dry Weather Flow (DWF) Sanitary Flow Average DWF must be subtracted from the allowable release rate when flow exceeds 10% of the allowable release rate It is possible to have an Average DWF larger than the allowable release rate Usually only significant on high rise buildings Stormwater Management Ordinance 22
Rate Control Unusual Cases Flow Diversion A flow diversion occurs when: The proposed sewer connection directs discharge to a different sewer than in the existing conditions A new source of water is introduced into the sewer Special release rate calculation that lowers the allowable release rate Rate Control Unusual Cases Allowable Release < 0.15 cfs Detention would use a pumped discharge to achieve a lower release rate, down to 0.06 cfs Stormwater Management Ordinance 23
Two Options: Volume Control Reduce impervious surfaces by 15% from existing conditions Capture 0.5 inch of runoff and store in Volume Control BMPs (Best Management Practices) Volume Control Impervious Area Reduction 2.0 Volume Control Spreadsheet Tool Tab 2.0 Volume Control Step 1: Runoff Calculation Existing Area (sq ft) Bare Earth Pervious Surface or Land Cover not Counted Lawn or Landscaped Areas as Impervious for Volume Control Calculations Woodlands Wetland Gravel Pavement Impervious Land Roofs (conventional) Water (including Wet Bottom Basin to HWL) Green Roof - Permeable Paving - Bioinfiltration - Swales - BMPs Stormwater Trees - Roof Runoff Planters - Filter Strips - Roof Runoff Planters - Dry Bottom Basins to HWL - Proposed Area (sq ft) Summary Total pervious area (sq ft) 0 0 Total impervious area (sq ft) 0 0 Total BMP areas treated as impervious area (sq ft) - 0 Total BMP areas treated as pervious area (sq ft) - 0 Total site area (sq ft) 0 0 Imperviousness percentage (%) 0.0 0.0 Step 2: Volume Control Assessment Question 1: Does the site drain directly to Waters? Type Yes or No for all that apply Note Question 2: Does the site meet all of the requirements of Sections 4.1.1 and 4.1.2 of the Regulations? Question 3: Do you wish to use permeable pavement only as a permeable surface to achieve impervious surface reduction goal? Step 3: Achieving Volume Control Measures Achieve I. or II. below in accordance with the Ordinance. Capture 0.5" of runoff from impervious I. surfaces. Storage required = 0 cubic feet Go to spreadsheet 2.1 BMP Volume Summary if electing volume control storage option or, II. Reduce proposed imperviousness to: - percent Stormwater Management Ordinance 24
Volume Control Impervious Area Reduction Adjust site plan to provide 15% impervious area reduction Stormwater Trees Must be on-site within 20 feet of on-site impervious surfaces Area credit available to help achieve 15% impervious area reduction Existing Trees 50 % of canopy size up to 50 sf Proposed Trees Up to 50 sf Volume Control BMPs Bioinfiltration Systems Drainage Swales Green Roof Permeable Pavement Roof Runoff BMPs Cisterns Planter Boxes Vegetated Filter Strips Infiltration Vaults Stormwater Management Ordinance 25
Volume Control BMPs Each BMP has: Specific design requirements Operation & Maintenance requirements Calculation methods a separate tab in the spreadsheet tool See Stormwater Ordinance Manual, Appendix C Volume Control BMPs Bioinfiltration Systems Stormwater Management Ordinance 26
Drainage Swales Volume Control BMPs Volume Control BMPs Green Roof Stormwater Management Ordinance 27
Volume Control BMPs Permeable Pavement Buckingham Fountain Permeable Pavers 2009 Stormwater Management Ordinance 28
Permeable Pavers Porous Concrete Stormwater Management Ordinance 29
Pervious Asphalt NOT RECOMMENDED Roof Runoff BMPs Volume Control BMPs Planter Box Cisterns Stormwater Management Ordinance 30
Vegetated Filter Strips Volume Control BMPs Volume Control BMPs Infiltration Vaults Stormwater Management Ordinance 31
Volume Control BMPs Infiltration BMPs will require geotechnical investigation Soil borings to establish soil composition and water table Infiltration testing to establish infiltration rate Infiltration BMPs require underdrains when infiltration rate < 0.5 in/hr Infiltration BMPs may not be practical because of: Shallow water table Contaminated soils Lot-to-lot buildings In these case, Oversized Detention would be allowed to meet the Volume Control requirements Operation & Maintenance Plan Many Stormwater BMPs will stop functioning if not properly maintained O & M Plan must contain: Owner Contact Information for post-constrution inspections Plan drawing of BMP locations with utility & BMP information O & M Practices Owner inspections Cleaning Regular maintenance Log book to keep records Implementation Schedule Employee Training Notes Owner s signature and notary Transfers to subsequent owners Stormwater Management Ordinance 32
Affidavits Two affidavits must be completed and signed for many projects: Infiltration Affidavit Design/Construction Affidavit in Support of Stormwater Infiltration or At-Grade Discharge of Downspouts on Residential Buildings Available in Regulations, Appendix II-B Required when proposing an infiltration BMP or downspout disconnection Erosion Control Affidavit Design/Construction Affidavit in Support of Soil Erosion and Sediment Control Measures during Construction Available in Regulations, Appendix II-C Required for all regulated developments Process DWM Stormwater Plan Reviewers at DOB DWM has technical control DOB has process control Training program for development community Stormwater Management Ordinance 33
Enforcement DWM will administer the ordinance Costs & Fees Apply to: Violations Plan Review Amendments Variance ($ in addition to Plan Review) Fees Stormwater Review Fee $1000 for sites < 50,000 sf $3000 for sites >= 50,000 sf Amendment $350 within 1 year $500 after 1 year Variance $1500 for sites < 50,000 sf $4500 for sites >= 50,000 sf Stormwater Management Ordinance 34
Variance Process Variance approval by DWM Commissioner Applicant must demonstrate exceptional circumstances: Exceptional physical constraints Nuisance to neighbors Landmark status Other code violation City of Chicago Contacts Department of Buildings (DOB) Stormwater Review 121 N LaSalle St, Room 906 Andrew Billing 847-774-3821 Ben Stammis 630-200-9430 Anand Devulapally 312-771-3481 Department of Buildings (DOB) Sewer Permit Section 121 N LaSalle St, Room 906 312-744-2515 Stormwater Management Ordinance 35
City of Chicago Contacts OUC (Office of Underground Coordination) 30 N LaSalle St, 3 rd Floor Jai Kalayil 312-744-4828 CDOT Division of Infrastructure Management (Deep Excavation Review) 121 N LaSalle St, Rm 906 Zenon Stuck 312-742-3130 Joe Tallud 312-744-8204 City of Chicago Contacts CDOT Project Development Nick Cayanan 312-744-7766 MOPD (Mayor s Office for People with Disabilities) Accessibility Review 121 N LaSalle St, Rm 906 Chris Zafiris 312-744-4441 or 312-744-7696 Fire Department 444 N Dearborn St John Javorka 312-744-1878 Stormwater Management Ordinance 36
Passing the Ordinance Developers Environmentalists Engineers City Staff Law Advocate Groups City Council & Mayor Resources Stormwater Management Requirements www.cityofchicago.org/water click Sewer Regulations Stormwater Management Ordinance 37
Urban Fabric Green Alley Program 1,900 miles of public alleyways in Chicago, the largest of any city in the world. Total of 3,500 acres of impermeable surface, the equivalent area of over 5 Midway Airports. Alley Summary Total: 13,000 Alleys 20% Currently Unimproved 20% in Need of Repairs Stormwater Management Ordinance 38
Project Sustainable Goals Stormwater Management Divert 100% of two year storm event from city storm system through the use of pervious pavements, bioswales and recharge of Chicago River through existing outfall Water Efficiency Transportation Energy Efficiency Recycling Divert 95% of Construction Waste from Landfills, Specify new materials with a minimum 20% Recycled Content Urban Heat Island Education No use of potable water sources for irrigation, Specify Native or Climate-adapted, drought tolerant plants for all plantings Improve bus stops with signage, shelters where possible, and lighting; facilitate use of bikes with lanes along Blue Island, and strategically located bike racks Meet IESNA Standards for Lighting Levels; select optimal street lights for energy efficiency; use reflective surface on sidewalks/roadways to improve lighting; use of renewable energy on designated fixture as demonstration Reduce ambient summer temperatures on streets and sidewalks through use of reflective pavements on roadways, light colored materials on sidewalks and use of trees for shading Provide public outreach materials/self-guided tour brochure to highlight innovative, sustainable design features of streetscape 21 Key Strategies Performance-based ordinance Sustainable Landscape Standards for all public landscapes Urban Forest Agenda Context-based design guidelines Multi-year implementation plan Stormwater Management Ordinance 39
17 BRANCH TUNNEL MEETS 27 MAIN TUNNEL Courtesy of MWRDGC Stormwater Management Ordinance 40
Thornton Reservoir 2004 1892-1900 Chicago School of Earth Moving Stormwater Management Ordinance 41
Courtesy of Metropolitan Water Reclamation District Stormwater Management Ordinance 42