Gwinnett County

Georgia Stormwater Management Manual (GCSMM technical basis / GSMM 2016)

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

Official GCSMM PDF is portal/HTML-gated. Criteria taken from GSMM 2016 (same technical basis Gwinnett publishes). Prefer swapping source to direct GCSMM PDF if a durable public URL appears. 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.required_hydrologic_hydraulic_software, document_metadata.relationship_to_state_manual

Other manuals in Georgia: Athens-Clarke County, Augusta, City of Atlanta, Coastal Georgia (Chatham County–Savannah region), DeKalb County, Fulton County, Georgia, Georgia, Macon

Document Metadata

Jurisdiction level

County

“Gwinnett County”
Coverage note

State

Georgia

“GEORGIA VOLUMES 1 & 2”
Title Page

Version / edition

2016 Edition

“2016 EDITION”
Title Page

Adoption / effective date

Not found in document

No evidence cited

Last revised date

Not found in document

No evidence cited

Relationship to state manual

Not found in document

No evidence cited

Design Criteria

Design storm return periods (years)

1-year, 2-year, 10-year, 25-year, 100-year

“the 1-year, 25-year, and 100-year return intervals... 2-year through the 25-year return frequency storm events”
105, 112

Water quality volume method

Sized to treat the runoff from 85% of the storms that occur in an average year, which equates to 1.2 inches of rainfall (Water Quality Volume, WQv), or the first 1.0 inch of rainfall using runoff reduction practices to the maximum extent practicable. If the entire 1.0 inch is reduced, the water quality volume may be waived. Otherwise, the remaining runoff from the 1.2-inch event must be treated to remove at least 80% of average annual TSS.

“treating storm events of 1.2 inches or less, as well as the first 1.2 inches of runoff for all larger storm events”
111

Peak flow calculation method(s)

SCS Curve Number Method

“SCS Curve Number Method”
154

Hydrologic/hydraulic software

Not found in document

No evidence cited

Approved BMP categories

Bioretention Basin, Bioslopes, Dry Wells, Infiltration Trenches, Organic Filters, Regenerative Stormwater Conveyance, Sand Filters, Stormwater Planters/Tree Boxes, Downspout Disconnects, Site Reforestation/Revegetation, Soil Restoration, Vegetated Filter Strips, Dry Detention Basins, Dry Extended Detention Basins, Multi-Purpose Detention Basins, Stormwater Ponds, Stormwater Wetlands, Gravel Wetlands, Enhanced Dry Swales, Enhanced Wet Swales, Grass Channels, Gravity Separators, Proprietary Systems, Underground Detention, Green Roofs, Permeable Paver System, Pervious Concrete, Porous Asphalt, Rainwater Harvesting

“Bioretention Basin; Bioslopes; Dry Wells; Infiltration Trenches; Organic Filters”
199