carbonate geology
carbonate geology
(OP)
I am designing stormwater detention structures for a site with extensive carbonate geology. It is evident because runoff from the entire 220+ acre drainage area passes through an existing 15" pipe without problem. There are also some sinkholes on the site. The problem I have is accounting for this carbonate geology in the stormwater runoff calculations. I have used PSU IV for other projects but the minimum drainage area for that method is 1 sq. mile. Any valid methods out there for accounting for carbonate geology when performing stormwater calculations?





RE: carbonate geology
RE: carbonate geology
Plan to install Class V injection wells in each sinkhole to assist the water in draining and prevent spectacular fall-outs. As the water percolates into the soil, it forms a vortex. If that vortex isn't contained in a pipe, it is very erosive and can have some pretty dire consequences for any near-by structures. Changing thet land use increases the amount of water draining to a sinkhole and this is when the sinkholes become unstable and fall out all over the place.
RE: carbonate geology
francesa - Thanks for your response. The pre-development drainage area totals 220+ acres which all drains to the existing 15" pipe. There are sinkholes on the site but none in the primary drainage course through the site. Therefore it can be concluded that runoff does not necessarily enter the ground through visible sinkholes. In fact there is a spring on the site which surfaces for a couple hundred feet of overland flow and then spreads out and disappears. There is no visible sinkhole, it just percolates through the soil. I have delineated the site into several post-development drainage areas which all drain to detention basins. The problem arises when I try to meet the pre-post flow reduction for this large area (much of which is not disturbed).
I am unable to create a reasonable pre-development model of the site which shows what runoff is doing on the site.
RE: carbonate geology
Engineering is the practice of the art of science - Steve
RE: carbonate geology
When you say "visible sinkholes" do you mean open throated sinkholes or depressions with no outlet?
I agree that the site is a bit on the small side for a regression model, but if you want to go that way, Kentucky Region 7 regression equations were developed for a Carst landscape. The soils generally are type B & C, and by the sounds of it you're dealing with a type A soil, so the equations may not be applicable.