Coastal Georgia (Chatham County–Savannah region)

Coastal Stormwater Supplement to the Georgia Stormwater Management Manual

OtherGeorgiahighNo

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

Other manuals in Georgia: Georgia

Document Metadata

Jurisdiction level

other

“Counties included within Georgia's Coastal Nonpoint Source Management Area include: Bryan, Brantley, Camden, Charlton, Chatham, Effingham, Glynn, Liberty, Long, McIntosh and Wayne.”
Section 1.2

State

Georgia

“Georgia Coastal Stormwater Supplement April 2009”
Title Page

Version / edition

First Edition, April 2009

“First Edition April 2009”
Title Page

Adoption / effective date

2009-04

“April 2009”
Title Page

Last revised date

Not found in document

No evidence cited

Relationship to state manual

independent

“this CSS was developed. It builds on the wealth of information presented in the GSMM... In case of a conflict between information presented in this CSS and the GSMM, the information contained in this CSS should be”
Section 1.6 Relationship of the Supplement to the Georgia Stormwater Management Manual

Design Criteria

Design storm return periods (years)

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

“providing 24 hours of extended detention for the stormwater runoff volume generated by the 1-year, 24-hour storm event”
Table 4.5 / SWM Criteria #3

Water quality volume method

Runoff Reduction Volume (RRv) for the 85th percentile / first-flush event: reduce runoff from the 1.2-inch rainfall event (and the first 1.2 inches of larger events); RRv = (1.2 in.)(Rv)(A)/12 with Rv = 0.05 + 0.009(I). Within 1/2-mile of shellfish harvesting areas, target is the 90th percentile / 1.5-inch event. Remaining unreduced 1.2-inch runoff must be treated in practices providing ≥80% TSS reduction and reducing nitrogen and bacteria to the MEP. Aquatic Resource Protection Volume (ARPv): 24 hours extended detention of the 1-year, 24-hour storm.

“In coastal Georgia, this equates to reducing the stormwater runoff volume generated by the 1.2 inch rainfall event (and the stormwater runoff generated by the first 1.2 inches of all larger rainfall events).”
Table 4.5 / SWM Criteria #1 Stormwater Runoff Reduction

Peak flow calculation method(s)

SCS Runoff Curve Number Method (NRCS, 1986), Modified Graphical Peak Discharge and Storage Volume Estimation Methods from TR-55 (NRCS, 1986), NRCS (SCS) unit peak discharge / Type II and Type III rainfall distributions

“modified version of the Graphical Peak Discharge and Storage Volume Estimation Methods presented in Technical Release 55 (TR-55) (NRCS, 1986).”
Section 5.4

Required hydrologic/hydraulic software

Not found in document

No evidence cited

Approved BMP categories

Soil Restoration, Site Reforestation/Revegetation, Green Roofs, Permeable Pavements, Undisturbed Pervious Areas, Vegetated Filter Strips, Grass Channels, Simple Downspout Disconnection, Rain Gardens, Stormwater Planters, Dry Wells, Rainwater Harvesting, Bioretention Areas, Infiltration Practices, Dry Swales, Stormwater Ponds, Stormwater Wetlands, Filtration Practices, Swales, Dry Detention Basins

“7.8.1 Soil Restoration... 7.8.3 Green Roofs... 7.8.4 Permeable Pavements... 7.8.9 Rain Gardens... 7.8.13 Bioretention Areas... 7.8.14 Infiltration Practices... 7.8.15 Dry Swales”
Section 7.8 TOC / Green Infrastructure Practices