pond outflow

[pdmhol]

my pond has nearly filled
i want the outflow to be an above ground ditch
thoughts on concrete or not?

 

[MiketheEngineer]

Concrete or steel - soil will erode

 

[cvg]

are you trying to conserve the water? - then concrete lined ditch or a pipe. Otherwise, any sort of erosion control method might work to protect a ditch depending upon your particular design.

 

[beej67]

Depends on the velocity of the discharge, which depends on the hydrology.

If you want to do it right, you'll need to know at a minimum:

Size of the watershed to the pond
Slopes / land cover of the watershed
Location of the property (to determine rainfall at your design storm)
Size of the pond

Then you design your outlet works so they won't erode at your design storm. This is a fairly easy (cheap) task for a hydrologist if you don't have to pull a permit. The difficulties (expense) arise when you have to get some sort of regulatory approval.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[3feethighandrising]

Depends on the slope of the outfall ditch. A rock armored ditch over geotextile will have a long life but will have reduced capacity on lower slopes compared to concrete. Concrete ditches on steep slopes will need engineered energy dissipation. Grass lined ditches will be cheapest to construct, provide some water quality but need max velocities of about 3 ft/sec to avoid erosion. Grass ditches may require maintenance (mowing).

Plan on calculating the 100-year stormflow rate for the basin, proving flow capacity using the Manning's Equation for channels, and providing 1/2 to one foot of freeboard to satisfy any regulatory approval.

 

[beej67]

Depending on the regulatory body, plan on a lot more than that.

Is routine maintenance of farm ponds exempt from regulatory approval? I know our friends in Ag sneak past a lot of the headaches have to deal with in land development.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com