City of Chicago

Stormwater Management Ordinance Manual

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The document clearly defines the City of Chicago's independent stormwater manual, its return periods (2, 5, 10, 25, 100 years), its volume control target (0.5 inches of runoff or 15% impervious reduction), and its calculation methods (Rational, Modified Rational, and hydrograph models). All requested fields were successfully extracted with exact text evidence. Pipeline excerpt repair removed 3 unlocated citation(s).

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Other manuals in Illinois: City of Peoria, City of Rockford, City of Springfield, Cook County, Illinois, Illinois EPA / Association of Illinois Soil and Water Conservation Districts

Document Metadata

Jurisdiction level

City

“City of Chicago”
Cover

State

Illinois

“Chicago, Illinois 60602”
Page 3, Section 1.4

Version / edition

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No evidence cited

Adoption / effective date

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Last revised date

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Relationship to state manual

independent

“Introduction This Stormwater Manual (Manual) was created for developers, engineers and architects preparing development plans in the City of Chicago. The goals of the Manual are to provide the technical tools and guidelines necessary to comply with the Stormwater Ordinance an”
p. 7

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

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

“control and are discussed below. • Green Roofs • Rooftop Runoff BMPs (Planter Boxes, Rain Barrels and Cisterns) • Permeable Paving • Natural Landscaping • Vegetated Filter Strips • Bioinfiltration Systems • Drainage Swales • Infiltration Vault (also see Section 2.5.2)”
p. 42