Connecticut

Connecticut Stormwater Quality Manual

StateConnecticuthighNo

Open source PDF ↗Official agency page ↗

Document Metadata

Jurisdiction level

state

“CONNECTICUT DEPARTMENT OF ENERGY & ENVIRONMENTAL PROTECTION”
Cover Page

State

Connecticut

“CT DEEP”
Page 2

Version / edition

2024 Edition

“Latest Revision March 26, 2024”
Cover Page

Adoption / effective date

2024-03-30

“Effective Date: March 30, 2024”
Cover Page

Last revised date

2024-03-26

“Latest Revision March 26, 2024”
Cover Page

Relationship to state manual

independent

“CONNECTICUT DEPARTMENT OF ENERGY & ENVIRONMENTAL PROTECTION”
Cover Page

Design Criteria

Design storm return periods (years)

2-year, 10-year, 100-year

“Control the 2-year, 24-hour post-development peak flow rate... Control the 10-year, 24-hour post-development peak flow rate... Potentially control the 100-year, 24-hour post-development peak flow rate”
Page 35, Table 4-1

Water quality volume method

WQV = (P)(R)(A)/12 where P = 1.3 inches (90th percentile rainfall event), R = volumetric runoff coefficient = 0.05 + 0.009(I) where I is the post-development impervious area percentage, and A is the drainage area in square feet.

“WQV = (P)(R)(A)/12 where: WQV = water quality volume (cubic feet) P = 1.3 inches (90th percentile rainfall event) R = volumetric runoff coefficient = 0.05+0.009(I) I = post- development impervious area (percent) A = post-development total drainage area of site or design point (square feet)”
Page 46, Water Quality Volume Calculation

Peak flow calculation method(s)

NRCS Curve Number method, Graphical Peak Discharge Method, TR-20, Rational Formula

“using a hydrologic/hydraulic routing model based on the NRCS Curve Number method (e.g., HydroCAD or similar software)... Graphical Peak Discharge Method... routing employed by TR-20... Rational Formula”
Page 59, Appendix D

Required hydrologic/hydraulic software

WinTR-55, HydroCAD, TR-20, Hantush Groundwater Mounding Spreadsheet

“hydrologic analysis software such as WinTR-55... HydroCAD or similar software... TR-20... USGS and New Jersey Department of Environmental Protection Hantush Groundwater Mounding Spreadsheet”
Page 55, 59, 190

Approved BMP categories

Pretreatment BMPs, Infiltration BMPs, Filtering BMPs, Stormwater Pond BMPs, Stormwater Wetland BMPs, Water Quality Conveyance BMPs, Stormwater Reuse BMPs, Proprietary BMPs, Other BMPs and BMP Accessories

“This Manual includes the following major categories and types of structural stormwater BMPs that are recommended for use in Connecticut, based on their primary function: Pretreatment BMPs, Infiltration BMPs, Filtering BMPs, Stormwater Pond BMPs, Stormwater Wetland BMPs, Water Quality Conveyance BMPs, Stormwater Reuse BMPs, Proprietary BMPs, Other BMPs and BMP Accessories”
Page 110-111, Functional Categories of Structural Stormwater BMPs