TPK wrote:Bwana architect,
I have a dug out a 10 feet deep, 8*8 feet wide septic tank in an area with hardcore kind of soil (I had to dig through rock from 2 feet to 10 feet) for a single dwelling unit and would appreciate if you could advise whether a) it is necessary to plaster it - My fundi tells me we should, to prevent rain water percolating and filing the septic quickly when it rains, but I asked a neighbour in the same area who has not plastered his and it has never filed for 2 years despite rains. b) Is it necessary to divide the septic into chambers? , how many columns should I have to prop up the septic shutter and how many beams should hold the shutter and is advisable to use Y12 or Y16? I would prefer that it is strong as possible to avoid the risk of it collapsing and injuring someone.
Finally, would you have some contacts of someone affordable to advise on structural integrity e.g where to have columns and can confirm what the fundi is doing - he is experienced but I prefer to have a second independent opinion particularly at foundation, slabbing and roofing.
Thanks.
mimi si architect, but as we await @4architect response I can throw a few observations, I am in the process of finishing an underground water storage and a septic and coincidentally the hard solid rock at my site was from around 3 feet to around 15, it had to be chipped slowly till they were through with it.
I would advice you to plaster since your neighbors rock structure might be different, you might have a crack and plastering latter after the septic is in use will be a herculean task.
In my thinking if your fundi has done your house and it is still standing, I think it wouldn't be hard trusting him with the septic tank - but bado sijasikia septic iko na y16 or propped up by columns, I usually see guys huko shags holding slab ya choo with poles and those things last for a very long time, unless you plan to weka some heavy tanks on top of the septic I would just go with your fundi, but I might be wrong.