Earthwall Dam
Earthwall Dam
(OP)
My Son-in- Law lives in Zambia and is farming tobacco and grains. On the farm is a medium sized dam built some two years ago. Whilst there recently I was taken on a tour of the farm dams shared by eight farms. The medium dam (Capacity not Known at this stage) has a seepage problem. Apaarently there where problems during construction, ie incorrect core materials, not confirmed. What came to my notice after a rather heavy rain storm, some 200mm over six daysI discovered a spring some 15Mtrs below the down stream side of the dam wall in the LH corner. I fyou are aware of the Teton Dam Disaster in 1976 in Idaho, USA you will see a similar patern but on of course a much smaller scale. "Q" What steps if any can be done without dismatleing the Dam can be taken. Any help will be appreciated





RE: Earthwall Dam
RE: Earthwall Dam
An emergency action could involve placing buttress material over the downstream toe of the dam. The material should be granular to allow drainage. The purpose is to provide both dead weight and a filter over the toe to prevent the erosion caused by the piping.
RE: Earthwall Dam
As CVG indicates, the additional weight will help mitigate the pore pressure issue and the additional filtering should help with the porosity/permeability. Additionally, simply lowering the water level will also help reduce some of the pressure at the base.
By the way, I got my geology degree from Idaho State University (located less than an hour away from the Teton Dam) so they tended to dwell on dam failures
RE: Earthwall Dam
RE: Earthwall Dam
The quantity of seepage should be carefully monitored by installing a weir and measuring the flow. If the quantity is not increasing for consistant pool levels then it is unlikely that significant piping is occuring. In this case the solution may be to just monitor the seepage. If the flow is increasing then action must be taken.
As noted above adding material to the area of the spring is likely the best option. However, the added material must be permeable and properly graded. The goal is to let the water out but not allow any soil to be carried with the water. If this is indeed the case, then a local geotechnical or civil engineer with experience with dams should be called in to look at the problem.
Also, how high is the dam (downstream toe to crest) and how far below the crest is the normal water level?
RE: Earthwall Dam
RE: Earthwall Dam
RE: Earthwall Dam
RE: Earthwall Dam