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Rain Garden
Rain Grove
Circular Depression
Planted Storm Water Buffer
Infiltration Trench
Sand Filter
Bio-swale
Porous Paving
Above Ground Cistern
Underground Storm Water Chamber
Preserved Wetland
Tree Protection Area
Habitat Protection Area
Riparian Buffer
Constructed Wetland
Parking Lot Detention
Grassed Swale
Vegetated Ditch
 
 
 

 

Preserved Wetland

Natural wetlands are nature’s way of handling storm water upon the land.  Wetlands function as collection and filter points for run off that begin at higher elevations on their journey toward the sea.

Wetlands are characterized as vegetated parcels of land that have standing water for part of the year. Wetlands are also delineated according to existing vegetation and soil types. The Corps of Engineers will designate as a wetland any low area meeting certain jurisdictional requirements of water, soil and vegetation.  Wetlands within cities are often low areas that trap and hold rainfall and may release it at very slow rates of water flow.   

The best wetlands for on-site storm water management are those wetlands that can be preserved on existing sites without any alteration or development. Should these wetlands be wooded or covered with a tree canopy, this storm water management area benefits the environment by saving trees at the same time it handles water.

 

Calculations

Watershed Area

The one (1) inch design storm watershed area includes the entire developed site within the property lines.

Square Feet x One Twelfth (1/12) Foot = Cubic Feet

65340 Sq Ft x 1/12 Foot = 5445 Cubic Ft

Cubic Feet ÷ Twenty-seven (27) = Cubic Yards

5445 Cubic Ft ÷ 27 = 201 Cubic Yards

Cubic Yards x Two Hundred Two (202) = Gallons

201 Cubic Yards x 202 = 40736 Gallons

Watershed Area = 40736 Gallons in a 1” Design Storm

Preserved Wetland (BMP) Capacity

Square Feet x One (1) Foot = Cubic Feet

19950 Sq Ft x 1 FT = 19950 Cubic Feet

Cubic Feet ÷ Twenty-seven (27) = Cubic Yards

19950 Cubic Ft ÷ 27 = 738.8 Cubic Yards

Cubic Yards x Two Hundred Two (202) = Gallons

738.8 Cubic Yards x 202 = 149255 Gallons

Preserved Wetland Capacity = 149255 Gallons 

BMP Capacity ÷ Watershed Area = BMP Percentage

149255 ÷ 40736 = 366% BMP Capacity for 1” Design Storm

1” BMP watershed design storm Gal ÷ 1” storm total property =

40736 ÷ 40736 =  100% BMP Management Factor

 

 

General Design Standards for Preserved Wetland

Wetlands, natural, constructed, reconstructed and jurisdictional unaltered in any manner may be retained as a storm water BMP. Natural wetlands be they wooded uplands, fresh water swamps, marshes, bogs riparian edges are one of nature’s natural water quality BMPs.

A minimum of fifty (50) percent of existing wetland on a project site may be retained, preserved or reconstructed on each development site. Protective barriers, eight (8) feet tall constructed of wood framing shall be installed for the duration of the construction process phase for any new development to protect these wetland areas from any incursions. Protective plantings or perimeter landscape improvements consisting of mixed shrub planting or one plant every thirty-six (36) inches may be added to guide development run off into natural habitat protection areas.

 

Click Here for more Technical Standards

 

 

Buck Abbey

309 Design Building
Baton Rouge, LA 70803
(O) 225.578.1475
(F) 225.578.1445
LSUGreenLaws@aol.com