cellar drainage

[ajl]

can anyone advise me? i am fitting a sump in my cellar ,i bought the house recently, there was a trench dug in the concrete floor to take water out. its been completely dry for 6 months and i am told it has been so since other houses have been built around me
(the last 6/7 yrs). anyway i will be absent a lot and wish to know i have any problem covered. so i am fitting the sump and a submersible. the question is. am i to leave the sump so that water can get in from its bottom and walls? thus allowing the pump to drain the sump before the level rises to the cellar floor itself. or am i to seal the base and walls and wait until the level in the ground is such that any water seeps in through the cellar walls ,then runs into the sump to be pumped out. i think the first solution is the best??? so long as any incoming (rising) water does not overcome the pump (unlikely) or the pump fails to start (possible) but applicable to both designs...!!

 

[JohnD]

It's Ok to have a bucket sized sump with the pump and float switch in it, no need to let your cellar flood - however - a point to be aware of - the water than runs into your sump is likely to bring the subsoil or sand into the hole with it, when you pump it out, more will arrive. This can result in the subsoil under your house being washed away and leaving a hole (!) unless you are on clay, then line the hole with a porous or no-fines concrete so that only "filtered" water will seep into it.

 

[ajl]

thanks for reply, good point about (fines). what i did in the end was . dig the hole, just over bucket size. then line the bottom with 2" waterproof concrete. then i sat a 300mm internal size concrete drain/culvert pipe in the hole, i figiured that this would probrably also be made of waterproof cement?? so i drilled a series of 5/8 holes around it about 1/3 the way up the side of the pipe. then i backfilled the hole with the rubble/clay type soil up to the origional floor base. then i filled the sides up to origional floor hight with waterproofed concrete. ???? i deliberatly did not do a perfect job of sealing the floor of the sump to the culvert pipe sides. what do you think? should i take any other action?

 

[JohnD]

Sounds OK to me though I expect the clay in your backfill will wash out unless it forms an impervious seal (probably won't as it takes a lot of puddling down to go waterproof).

The sump should accumulate any slow seepage, and in the event of a substantial flood it will run into the sump anyway and get pumped out. Hope all your electrical connections are above flood level


Other action? some kind of grille over the hole so no-one breaks their leg in it

 

[ajl]

thanks lots. well if the electrical connections get wet i have other problems as the socket is 4 ft up the wall. the cellar is also a garage, ie only undeground on one side.
as to the sump. i should of thought of that, i could have put it just inside the exterior door to the cellar, at least it might get the burgular then!!!
seriously .thanks