Choose The Right Site For The Dam
As with most construction projects, building a farm dam begins with selecting the right site. A poorly located farm dam can lead to degradation of the surrounding land and can be expensive to maintain. In general the best place for a farm dam is in a gully or depression. Avoid steeper sites and make sure that their is plenty of suitable soil available for constructing the walls. Stay away from sites which feature material that is prone to tunneling such as gravel, sand and rock.
Constructing The Farm Dam
If you are building a farm dam to hold over 250 cubic meters then you will typically need to employ a bulldozer with rippers. Start by pegging out the site carefully. Next clear away all of the vegetation that will be disturbed during the construction. Remove the topsoil from the excavation site and pile this at the bottom of the wall, so that it can be spread out later. Next you will need to construct a cut off trench. This is a trench excavated under the wall in order to prevent seepage. The impervious material will be removed and then replaced with clay. Once the trench has been dug begin building the wall layer by layer. The clay needs to be spread in even layers of no more than 150mm for each layer. If there is exposed rock on the floor of the dam it should be covered with clay at least 300 mm thick. You will also need to construct an earth spillway. This is a channel that will safely redirect surplus flows past the wall. There should also be at least a one meter free board from the top of the water level to the top of the dam wall. Finally spread topsoil over the top of the dam wall and seed with grass to promote vegetation which will add stability to the wall.
To make sure that your farm dam continues to hold and store water it is important to maintain it properly. Avoid damaging the spillway, continue to grow grass on the wall and don’t grow trees on the embankment. These preventative measures will ensure the maximum stability of your farm dam. To be sure you get your dame constructed the right way from the start, make sure you hire a professional earth moving contractor and avoid hassles in the years to come.