City of Chicago

Stormwater Management Ordinance Manual

CityIllinoishighNo

Open source PDF ↗Official agency page ↗

Document Metadata

Jurisdiction level

municipality

“City of Chicago”
Cover

State

Illinois

“Chicago, Illinois 60602”
Page 3, Section 1.4

Version / edition

August 2024

“August 2024”
Cover

Adoption / effective date

2024-08

“August 2024”
Cover

Last revised date

2024-08

“August 2024”
Cover

Relationship to state manual

independent

“The purpose of this 'Stormwater Manual' (Manual) is to help applicants understand and comply with the Ordinance and accompanying Chapter III 'Requirements for Stormwater Management' of the 'Regulations for Sewer Construction and Stormwater Management' (Regulations).”
Page iv, Foreword

Design Criteria

Design storm return periods (years)

2-year, 5-year, 10-year, 25-year, 100-year

“Velocities must be 1 ft/sec or less during the 2-year storm event... minor drainage systems for small storm events of up to the 5-year storm event... storage for a minimum 10-year event... 25-year storm analysis... 100-year storm event”
Pages 7, 14, 24, 36, 39

Water quality volume method

Capture one-half inch of runoff from all impervious surfaces, or achieve a fifteen-percent reduction in impervious surfaces from existing conditions for developments not discharging to Waters or MS4.

“Capture one-half inch of runoff from all impervious surfaces in accordance with volume control BMPs; or (B) For Developments that do not directly discharge to Waters or to a municipal separate storm sewer system, achieve a fifteen-percent reduction in impervious surfaces from existing conditions.”
Page 26, Section 3.2

Peak flow calculation method(s)

Rational Method, Modified Rational Method, Hydrograph Methods, HEC-1, HEC-HMS, TR-20, TR-55, SWMM

“Modified Rational Method to calculate the maximum volume of stormwater... Rational Method... hydrograph methods with regional rainfall data... HEC-1 and HEC-HMS... TR-20... TR-55... SWMM”
Pages 7, 15, 16, B-6, B-7

Required hydrologic/hydraulic software

Stormwater Spreadsheet Tool

“The initial site plans, Stormwater Management Plan (SMP), Stormwater Spreadsheet Tool and all other supporting documentation must be submitted to DOB”
Page 3, Section 1.4

Approved BMP categories

Combined Sewers, Ditches, Swales, and Natural Channels, Storm Sewers, Detention Basins, Detention Vaults, Oversized Pipes, Parking Lot Detention, Rooftop Detention, Green Roofs, Rooftop Runoff BMPs (Planter Boxes, Rain Barrels and Cisterns), Permeable Paving, Natural Landscaping, Vegetated Filter Strips, Bioinfiltration Systems, Drainage Swales, Infiltration Vault

“Green Roofs... Rooftop Runoff BMPs (Planter Boxes, Rain Barrels and Cisterns)... Permeable Paving... Natural Landscaping... Vegetated Filter Strips... Bioinfiltration Systems... Drainage Swales... Infiltration Vault”
Page 36, Section 3.3.1