Understanding Sump Pumps

[DarrenSL]

I have a drainage problem at the front of my house which results in my garage getting regularly flooded, not to mention a semi permanent pool of water up against the brickwork of the house (albeit below the dpc).

All the drains are located to the rear of the property although there is one surface drain to the side of the garage approximately 3m back and 50cm higher than the garage floor. The drain runs towards the back of the property.

The soil around the property has a high clay content so I expect a natural drainage pit won't work.

My proposal is to dig a trench (approx 1m deep) fill it with gravel and have a sump pump within an inspection chamber at one end. Unfortunately I know nothing about sump pumps so could do with some advice please.

How are permanent sump pumps normally fitted?
Can the pumps be completely submersed, electrics and all?
Which pump would be best suited for the job? (the pit will sit at the bottom of a single car downward sloping drive amd will also have to deal with water draining from the front garden (8mx5m)).

Many thanks.

 

[breezer]

normaly a sump pump is plugged in (they come with a plug, but you could also use an fcu to stop any one switching it off, but it must be on the rcd side of your consumers unit, if you have no rcd, buy a plug in one and plug the pump into that.

yes the whole pump sits in the water, you want one with a float switch, the switch will automaticaly switch the pump on and off as required

this one has a float switch, screwfix no longer supply them with float switch

the sump you build should have a concrete slab in the bottom (pump sits on this) so the pump sucks no more dirt than necessary, the float switch needs to be able to move

 

[DarrenSL]

Cheers Breezer. Especially, the tip re: concrete slab at the bottom!

 

[Belle427]

also check when you buy which are suitable for clean water and dirty,some pumps can handle small solids and are generally heavier duty and less troublesome

 

[3GHOTHEAD]

mmm I agree with CH, the substrates will collect at the bottom of the pit especially with clay in the form of a slurry. Over time this will harden and jam the pump espacially the light duty plastic one illustrated( I have one).
Correct me if ime wrong but i would use an SWA cable on a waterproof outlet between the consumer and the outlet near to or fixed in the chamber. I recon its a lot of hard work for little gain. If the top of the surface water drain is only 50mm obove the garage floor and 3.0m away , cant you dig it up and find a way of connecting on to this pipe lower down and run a 3.0 m length of 100mm pipe to a french drain type arrangement.? A decent inline gulley would be wise to use as well

 

[DarrenSL]

Fitting a linear drain straight into the drainage system (via a suitable trap) would be ideal but I'm not sure if I have sufficient drop. I said previously that the grid was 50cm higher than the garage floor. On measuring, this is actually only 20cm! The drain itself the runs immediately off under the kitchen extension at the rear of the garage.
I guess the only way to find out would be to break up the drain and find out (unless anyone else has any ideas).

Also, is it OK to run a ground drain straight into the system or is it likely to silt up and cause problems. Should I run this into the linear gulley or via a junction pipe after the p trap?

Thanks for your advice.

 

[JohnD]

you are not allowed to put groundwater into the sewage system.

If you make your sump rather deeper, so water can settle, with the pump not at the very bottom, it will pull out less suspended solids.

Another way for slow seepage is to line a pit with no-fines concrete which is very porous and will strain a lot of the solids to prevent them getting into the pit. Lining your french drain with permeable membrane will also help.

Pumping away suspended solids will eventually cause settlement and maybe subsidence as you are pumping the ground away. But if the flow is very slow once you have reduced the water table that will be better. Presumably you have already dealt with all gutters and downpipes to prevent them discharging on the ground.

 

[DarrenSL]

Thanks John. The downpipes flow into the aforementioned side drain so no problems there. I'm not sure if the house has separate sewage/surface water drainage systems as there are no manholes anywhere around the property just two rodding eyes at the side. (the house is 30yrs old).

Is it ok for the groundwater to drain into a combined system do you know?

 

[JohnD]

I'm pretty sure it's not allowed into any system.

You might find your french drain acts as a soakaway if it's deep.

 

[DarrenSL]

A soakaway may be the best option but I believe these need to be situated approx. 5m away from the property. This is not a viable option given that the front garden and drive is only 5-6m and slopes significantly towards the house. The side of the house is also not an option as its only a couple of meters wide on both sides.

Currently all the surface water drains away naturally over time but this is nowhere near quick enough and regularly results in flooding. More concerning is the fact that the house is now showing signs of subsidence as the underfootings are gradually being washed away.

It really looks as though I have little option but to drain into the main drain, with or without permission.

 

[JohnD]

You almost always have an option not to break the law if you choose.

Does the back garden slope towards the house or away? What is the lowest point in your property where you could put a soak away or a garden pond?

 

[DarrenSL]

I guess there is another option (but it sounded like a lot of hard work so I've tried to avoid it ). Other than the sloping front garden the property and rear garden is level. The rear garden is appox 15m long with a river (1m down) at the end behind a row of conifers. QED you say, but thats an awful lot of digging and disruption. Then again, 'if needs must'.

Thanks for helping thrash out the ideas

 

[JohnD]

Hire a mini-digger and charge all your mates £10 for a go on it.

 

[DarrenSL]

 

[DarrenSL]

OK, after much deliberation I've decided to go with the sump pump option as I really don't fancy digging a 20m trench, and theres no guarantee that the soak-away will work (given the high clay content) and the alternative of continuing the run into the river at the back will involve felling trees and destroying the man made stream wall (which I don't own!).

So, this is my proposal. A gravel pit is not necessary (imo) and a simple gulley draining straight into the sump pump pit will suffice. I can also run the garden drain straight into the pit too. I plan to use a permeable membrane around the garden drain to minimise the amount of silt and debris flowing into the pit.

I plan to use this pump



The only factor I'm not sure about is how to connect up the pump to 32mm pvc pipe in a way that looks respectable?
Also, I could do with some support from you guys as to whether my logic and reasoning is sound!

Here are some pictures to help visualise the problem ...

http://i66.photobucket.com/albums/h261/DarrenSL/IMG_2049.jpg
http://i66.photobucket.com/albums/h261/DarrenSL/IMG_2046.jpg
http://i66.photobucket.com/albums/h261/DarrenSL/IMG_2044.jpg
http://i66.photobucket.com/albums/h261/DarrenSL/IMG_2045.jpg
http://i66.photobucket.com/albums/h261/DarrenSL/IMG_2047.jpg

And here is the proposed plan ...
http://i66.photobucket.com/albums/h261/DarrenSL/GaragePlan2.jpg

Cheers!