Birchy
Civil/Environmental
- Apr 22, 2005
- 3
Hi all!
My client wants to build a small residence (@ 110 sq. m footprint) in a coastal zone with a high water table. Soil borings show standing water at - 58" and a seasonal high water table at - 38". He wants a full cellar and is willing to live with a bit of dampness if necessary. Local land use regulations would put the top of the floor slab no higher than 45 to 48" below grade (otherwise the "cellar" becomes a "basement" and must be counted as a "story").
I have never designed a cellar with a floor below seasonal high water or so close to the water table. My calculations suggest that by excavating right down to the standing water and then placing a rubber membrane, 6" of coarse gravel and 6" concrete slab, we will have a slab with its top at - 46" that will not "float" under worst case scenario. I would also place two independent drain tile systems, one under the slab, and one a bit higher outside the footings, both piped to two sump pits and pumped to daylight. The foregoing, however, is purely academic. Does anyone have some real world experience in this area that they would be so kind as to share?
Thank you all.
![[ponder] [ponder] [ponder]](/data/assets/smilies/ponder.gif)
My client wants to build a small residence (@ 110 sq. m footprint) in a coastal zone with a high water table. Soil borings show standing water at - 58" and a seasonal high water table at - 38". He wants a full cellar and is willing to live with a bit of dampness if necessary. Local land use regulations would put the top of the floor slab no higher than 45 to 48" below grade (otherwise the "cellar" becomes a "basement" and must be counted as a "story").
I have never designed a cellar with a floor below seasonal high water or so close to the water table. My calculations suggest that by excavating right down to the standing water and then placing a rubber membrane, 6" of coarse gravel and 6" concrete slab, we will have a slab with its top at - 46" that will not "float" under worst case scenario. I would also place two independent drain tile systems, one under the slab, and one a bit higher outside the footings, both piped to two sump pits and pumped to daylight. The foregoing, however, is purely academic. Does anyone have some real world experience in this area that they would be so kind as to share?
Thank you all.
![[ponder] [ponder] [ponder]](/data/assets/smilies/ponder.gif)