Garden drainage and surface water problem.


Postby Cluey » Sun May 04, 2008 6:00 pm

Hi, my wife and I moved into our new build house just over a year ago. Since then we have been gradually working with the garden but have now hit a problem after what seems like 9 or 10 months of continual rain. The rear garden slopes away from the house very slightly and is made up of a clay/clay type soil. Recently the lawn has become waterlogged, and drains away very slowly, at the rear of the garden a large puddle often accumalates after heavy rain.
A soakaway has been suggested but as the soil is very heavy and is't particularly good at draining away I don't think this will work. It has also been suggested to put in some drainage under the lawn and have these feed into a dran of some sort near to the house. However, as the garden slopes away from the house I can't see how this could be achieved. What other options (if any) do I have?
Cluey
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Joined: Sun May 04, 2008 5:51 pm

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Postby ALDA » Sun May 04, 2008 7:06 pm

C,

THE SOAK AWAY PROVIDES A KIND OF "RESIVOIR" WHERE EXCESS WATER CAN GATHER ASWELL AS MEANS OF INCREASING THE SURFACE AREA AVAILABLE TO ASSIST WITH DRAINAGE.

I HAVE MADE A LOT OF ASSUMPTIONS HERE IN ORDER TO AFFECT A REMEDY AS FOLLOWS:-

INSTALLING DRAINAGE BACK TOWARDS THE HOUSE CAN ONLY BE ACHIEVED BY HAVING A FALL IN THE PROPOSED DRAINAGE TO THE EXISTING/REQUIRED ENTRY POINT (THIS IS LIKELY TO BE AT THE BASE OF A MANHOLE OR CHAMBER AT SAME LEVEL AS EXISTING DRAIN PIPES AND WILL INVOLVE A LOT OF DIGGING TO ACCESS AND POSSIBLY WATER AUTHORITY PERMISSION).

IF THERE IS A WALL AT THE BOTTOM OF THE SLOPE THAT IS PREVENTING THE EXCESS WATER FROM ESCAPING YOUR GARDEN, THEN IF THIS WALL CAN HAVE DRAIN HOLES/PIPES PUT THROUGH, THIS WILL HELP THE PROBLEM SIGNIFICANTLY AND THIS "EXIT POINT" COULD BE UTILISED EVEN IF THERE ISN'T A WALL USING DRAINAGE TRENCHES/PERFORATED PIPES BACK FILLED WITH GRAVEL (MAY REQUIRE NEIGHBOURS CONSENT IN BOTH CASES) IN AN EFFORT TO GET RID OF THE WATER FURTHER DOWN SLOPE.

FOOD FOR THOUGHT,

ALDA.
ALDA
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Joined: Mon Feb 04, 2008 8:15 pm


Postby Carolyn » Mon Jul 14, 2008 5:22 pm

Alda - I have a similar problem as Cluey's, but with a large section of our lawn in the backyard. Our yard is lower than our neighbors and we tend to get all of the rainwater runoff in our yard. After heavy rains or in the Spring when the snow melts, we have a soaked lawn for months. We've had to replace a new tree due to the wet ground and were told by the planter that we have a lot of water under the ground. Our soil is also mainly clay. In our case, our manhole/sewer is located at the back of our yard on the opposite side of the yard that we have the soaked lawn. A soakaway with a PVC pipe for drainage was suggested by a friend. Reading your discussion with Cluey, I am assuming we'll need to run this across the yard to the manhole which may require the city's approval/assistance as well??? Any other suggestions you might have?
Carolyn
Posts: 1
Joined: Mon Jul 14, 2008 4:56 pm


Postby Bob Plum » Tue Aug 05, 2008 1:29 pm

Digging a soakaway in clay will not work unless the clay overlies free-draining soil and the soakaway goes down into it, and the water-table is low. Digging a hole (which is basically what a soakaway is), in water-logged ground is like digging a hole in a marsh - you get a pond in the middle of a marsh.
Cluey's puddle must accumulate becasue there is effectively a dam stopping drainage - breaching that dam in some way is the only way to stop it forming and improving darainage in general, as Alda says. But what is at the end of the garden that will receive the run-off?

There is no simple answer to either problem because connection of surface water drains to anything but a surface water main drain (rather than a foul drain) is generally illegal, and relatively few houses have surface types anyway, and you'd need permission to make the connection - and probably pay extra water rates as a consequence. If you contemplate drainage of any type make certain that falls are correct and traps are fitted where appropriate. (Draining against the lie of the land is simple enough - you dig a trench that slopes into/against the slope of the land).
Bob Plum
Posts: 15
Joined: Tue Aug 05, 2008 12:56 pm


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