Advice on lawn drainage.

Lady Penelope

Hey All
We live in an estate with a normal sized back garden which for the past 3 years is more like a swamp. We have tried drainage with gravel, piercing soil and putting grit down to all to no avail. I thin we should dig it up but don't know what to then?? Do we get all new soil, put a gravel bed in or pipe system??
Any advice on what to do would be very thankfully received.

willbur

does your house back on to other house,s or is there a ditch
where is the lowest part of the garden ie the very end or near the house
does it get very wet after recent rain or is it wet all the time
is there any land near you that is higher than yours:cool:

Lady Penelope

we have houses behind us. it has rarely dried out only in very dry spells. its wet all over both at the back at near the patio at back of house. all gardens around us are pretty much on the same level.

Sonnenblumen

Could be a number of reasons, most likely a high water table but if it is persitently wet, probably remote aspect of a 'flood plain'. Drains are unlikely to resolve your problems, so likely solutions will be excavate area/remove soil and backfill with various grades of gravel, adding land drains at lower level will help (but you need to plan what to do with the run off?). Drains must be down at least 900mm on a bed of 150-200 coarse gravel and backfill with drainage gravel to approx 50 mm from surface. Blind and compact surface with approx 20mm hardcore/3mm grit, and topdress with 25mm of preferred stone pebble/chipping. Alternatively you might consider paving part of the area, in which case you will require a sub-base (100-150mm) of compacted hardcore before installing paving.

To add greenery, probably better to install Raised Beds, which can be constructed from a range of materials including build stone, pine sleepers, concrete block etc etc.

If however a soft surface was preferred (as children's play area) you could consider installing a lawn using synthetic grass (free draining, little maintenance and a very good alternative to a soggy lawn).

Minder

There may be an application here that you could use. I've seen these drainage crates advertised in the construction papers. Used in building soakaways or for water collection, a series of modular plastic crates are buried - the voids within the crates provide storage space for excess water and allow it to gradually seep away. The crates are wrapped in a permeable geotextile that will allow water into the box, but keep the fine material in the soil from entering. The voids are much greater than conventional soakaways, so more water storage and the crates are strong enough to be used in carparks etc.

There is no easy solution and some site investigation would be required to determine the soil types. It would be pointless installing these only to find that you have the same problem if the water cannot escape and the box is full. It may be possible to connect the box to a surface water sewer and allow the water to run off. See if you can find a groundworks contractor who knows about SUDS - Sustainable Urban Drainage Systems - and pick their brains.

BTW Burdens is at least one supplier who sell the crates - there are three depots in Ireland, Dublin, Cork and Belfast.

tam_c

hi there i do a bit of drainage as i work in the construction buisness.

if you have a rodding eye at the back of your house you could use that to put a french drain into it only if the rodding eye is storm water as you dont want to break ino the toilet pipes.

a french drain consists of the following.

dig the place you want the water away from at least a metre down line it with terram.
connect to the rodding eye with a y branch
then fill the base up with pea gravel up at least 400 mm
you then put down perforated pipe in position and connect to the y branch
fill up with another 400 mm of pea gravel. fold the terram over and then place top soil over the terram and that should work.

the idea of that is the peas soak the water in and seeps into the pipe to allow it to flow into the main system without you having to break into sewers and that.

starbelgrade

House building sites often have heavy machinery moving over them, compacting the soil of new gardens. As a result, water cannot drain through it properly which causes the puddling.

Before deciding on what remedial action is necessary, dig a narrow, sharp sided pit about 60cm deep. There should be a dark subsoil layer at least 20cm deep above a paler subsoil. The subsoil should be open & friable. If the soil is hard & compacted, careful cultivation is required.

Once you've examined the pit, fill it with water, cover & leave overnight. If the water is still there, raised beds for planting is definitely advised & a drainage system may be required.

Usually though, the easiest & cheapest solution is to dig out a layer of the soil & remove any debris & rubble the builders have left behind & add topsoil. Make sure the topsoil is good quality as cheap stuff will just give you loads of weeds & other problems.. it should be screened to remove weed & debris & sterilised to kill bacteria & pests.

My garden was like a swamp too - but that solved the problem... it still gets a bit waterlogged during the wet months, but this can be fixed by aerating the soil with a fork.

Land drains & soakaways are not easy or cheap to construct.

Sonnenblumen

Lady Penelope wrote: »

Hey All
We live in an estate with a normal sized back garden which for the past 3 years is more like a swamp. We have tried drainage with gravel, piercing soil and putting grit down to all to no avail. I thin we should dig it up but don't know what to then?? Do we get all new soil, put a gravel bed in or pipe system??
Any advice on what to do would be very thankfully received.

Hi Lady P

an alternative solution might be to instal a synthetic grass lawn. It is an ideal solution for very damp sites where normal grass is not feasible but a lush green dry surface is required.

In exceptional wet areas, ground can be raised to provide a more free draining site conditions before installtion of new lawn.

Various grades are available from cheap and cheerful to midrange (family/kid sports) to lush ornamental. Note cheap but the results are impressive.