Cook County

Technical Guidance Manual for the Implementation of the Watershed Management Ordinance

CountyIllinoismediumNeeds reviewCitations verified

This extraction is flagged for quality review.

Compare each cited field to the official PDF before relying on it. What this means

Extracted from MWRD TGM PDF (538 pages; text truncated/encoding degraded for some symbols). Criteria focus on Article 5 volume control (1 inch) and detention release-rate matching. WMO amendments after TGM compile may add detail. Pipeline excerpt repair removed 1 unlocated citation(s).

Fields not found in document: document_metadata.adoption_or_effective_date, document_metadata.last_revised_date, design_criteria.design_storm_return_periods_years, design_criteria.required_hydrologic_hydraulic_software, document_metadata.jurisdiction_level

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

Document Metadata

Jurisdiction level

Not found in document

No evidence cited

State

Illinois

“Metropolitan Water Reclamation District of Greater Chicago”
TGM Introduction

Version / edition

MWRD TGM (compiled articles; Article 5 stormwater)

“Technical Guidance Manual”
Footer

Adoption / effective date

Not found in document

No evidence cited

Last revised date

Not found in document

No evidence cited

Relationship to state manual

independent

“Watershed Management Ordinance (WMO) ... Cook County”
Introduction

Design Criteria

Design storm return periods (years)

Not found in document

No evidence cited

Water quality volume method

Volume control storage equals one (1) inch of stormwater runoff from newly developed impervious surfaces, treated using retention-based volume control practices first, then flow-through practices for any untreated portion. Site detention release rate must not exceed existing runoff rate (or calculated allowable release rate, whichever is smaller). Volume control storage may credit against required site detention volume.

“requires that one (1) inch of stormwater runoff from all impervious surfaces of the development be treated using volume control practices”
Article 5 — Site Volume Control Requirements

Peak flow calculation method(s)

Existing vs proposed runoff comparison (no increase), Site detention with allowable release rate, Curve number method (CN tables in TGM)

“allowable release rate from the site shall be either equal to or less than the existing runoff rate”
Article 5 — Site Stormwater Management

Hydrologic/hydraulic software

Not found in document

No evidence cited

Approved BMP categories

Retention-based volume control practices, Flow-through practices (vegetated swales, filter strips, oil/grit separators), Site detention facilities, Erosion and sediment control BMPs

“For mechanical flow-through practices, such as an oil and grit separator, an effective maintenance plan is based on performing frequent inspections. The rate at which these devices collect pollutants will vary from site to site, and therefore frequent inspections (onc”
p. 413