Weep hole design

[longisland]

Is there any write up on weep hole design for retaining wall? I'm especially intereted in how one would specify the spacing & size of the weep hole. Most retaining walls are seperated by a layer of cohesionless material such as sand, aggregates, rock frafment etc. I'm assuming the layer of sand & the weep holes serve to release the hydrostatic pressure & lowering the water table. However, the rate of flow or seepage is not addressed. Thanx in advance

 

[georam]

In general, a book on Groundwater and seepage by Cedergreen provides general information about seepage flows, flow nets, etc.<br>
<br>
In your case, the expected volume of water per width of wall, for example can be estimated by completing a flow net. That would provide some idea on spacing of the weep hole. For the size of the hole, it should be adequate for the flow, without washing the materials behind.

 

[DDawson]

You may want to consider using a geotextile designed to reduce hydrostatic pressure to zero with a colletion pipe at or near the base of the wall. I design walls in an area with annual rainfall in excess of 65 inches and I know that I dont have hydrostatic pressure this way. <br>
Stripdrain 80 from Contech Construction Products, Portland, Oregon ) is one such geocomposite drainage system, there are many many others out there to choose from.<br>
Regards...