Difference between revisions of "Dry ponds"

From LID SWM Planning and Design Guide
Jump to navigation Jump to search
Line 15: Line 15:
*''A<sub>c</sub>'' = Area of the catchment (m<sup>2</sup>)
*''A<sub>c</sub>'' = Area of the catchment (m<sup>2</sup>)
*''q'' = infiltration rate (mm/hr)
*''q'' = infiltration rate (mm/hr)
*''t'' = [[draw down]] time (hrs)}}
*''t'' = [[drawdown]] time (hrs)}}


----
----

Revision as of 17:59, 29 September 2017

Also known as infiltration basins.

Overview[edit]

Dry ponds are recommended as flood control structures to accommodate occasional excess overflow downstream of other structural BMPs. They should be integrated into the landscape as useful, accessible public space.


Design[edit]

Sizing

The surface storage volume of a dry pond (Ap) is simply determined:

Where:

  • RVCT = Runoff volume control target (mm)
  • Ac = Area of the catchment (m2)
  • q = infiltration rate (mm/hr)
  • t = drawdown time (hrs)

Modeling[edit]

Dry ponds are found in storage element in the LID TTT
The largest area is at the top, level 0 m; each subsequent lower depth has a smaller area

TTT.png

A dry pond as a storage element (key parameters) in the Treatment Train Tool.
Stage Storage
Name Important to have a unique name, to connect it with the catchment area
Storage type Dry detention ponds
Bottom elevation (m) This is important to correspond with other components,
e.g. when the overflow is coupled to another BMP within a treatment train
Maximum depth (m)
Lined/unlined Unlined (ideally)
Underlying soil Choose from five; sandy soils drain more quickly.
Evaporation factor ?
Suction head (mm) ?
Saturated conductivity (mm/hr) ?
Initial soil moisture deficit (fraction) ?
Curves
The Curves table is designed to accommodate the side slopes. The top line begins at 0 m, with subsequent depths in the following lines.