2 Case Studies: Dealing With Severe Garden Drainage Issues

Increasingly as landscapers, we are asked to devise solutions to customers garden drainage problems.

Whilst we have many years’ experience in installing land drains and other drainage systems for our clients, in recent years we have had to become somewhat more creative in our drainage problem solving.  The design of modern housing developments, accompanied by the high level of rainfall in recent years and in some instances a lack of maintenance of public drainage systems all contribute to a seemingly increasing problem.

Two recent case studies – one completed, one in progress:

Lower Earley (Completed)

House Type: Modern link detached semi

Garden Situation: Small back garden at a considerably lower level than the houses beyond (perhaps 2-3m lower).  Also a tiny bit lower than the gardens either side.  Existing garden on two levels: a shallow lower level near the house, and a higher level further up the garden.

Soil Type: Very heavy clay soil.  Soil also compacted and still contained builder’s rubble.

The Requirement:

The client had requested (amongst other things) a larger patio near the house, allowing four people to sit comfortably around a table – not an unreasonable request!  Our initial design included a new retaining wall and steps (further away from the house), plus the new patio.  As we knew the garden would be acting as a kind of sump for the higher gardens at the back of the property, extensive gulley drains were installed, and connected to a huge new soakaway.  However, in the recent heavy rains, it quickly became apparent that this, or any other kind of soakaway-based solution, would not be adequate.

Solution:

Unfortunately all the rain water pipes and storm drainage were in the front of the property.  As a temporary solution, we installed a small automated pump to pipe the water through the garage to the storm drains in the front of the property – the pump only operating when the level of water in the pump chamber rose above a certain level.  This was followed by the installation of a permanent, gravity fed system, entailing the installation of permanent pipework under the garage floor.  The temporary pump is shortly to be removed.

Crowthorne (In Progress)

House Type: Detached modernised house

Garden Situation: This house is situated at the bottom of a dip in the surrounding area.  There is also a small stream adjoining (part of the Emm Brook system).

Soil Type: Various – a mixture of clay and loam

The Requirement:

The garden has always tended to get quite wet after heavy rainfall, as it receives the run-off from the surrounding land.

The client had already installed pumps and pipes to drain the garden into the adjoining stream.  The original plan was for us to simply redesign the border shapes and planting, with some relatively minor changes to the structure of the garden and the hard landscaping.

However, the excessive rainfall just before and after Christmas caused a dramatic change of plan as the entire garden and garage floor was totally submerged under 150-200mm of water.  Our client had to make frantic efforts to prevent water entering the house.  Fortunately the stream itself did not breach its banks (although it was mighty close) – the flooding was due to the sheer volume of surface water run-off, over a relatively short period of time.

The Solution:

The client is now in discussion with the various public authorities to shore up the banks of the stream.  Meanwhile, we are working with the client to devise a long term drainage solution for the garden, embedded within an attractive overall garden design.

Our solution will incorporate new low retaining walls, drainage pipes, and the gentle re-grading of  some parts of the garden.  Crucially, the design will include a wide, sweeping  gravel path to a new raised sun terrace, acting as a vital catchment area and drainage system route through the garden.  Clever positioning of this gravel path will allow us to hide a large pumping station/chamber and some heavy duty wide draingage paths underneath.

The lawn and borders will be shaped on either side of the path to ensure that the garden appears a harmonious whole.   Another option would be to design the gravel path as a kind dry stream (although in reality it will often be far from dry below the surface!).

In Summary

Neither of these two gardens are on a flood plain.  Both are good examples of how terrain, soil, weather conditions and other factors can combine to cause huge practical garden drainage problems.

In recent months ALDA Landscapes have also installed drainage solutions in gardens in Maidenhead, Wokingham, Hartley Wintney, Twyford, and elsewhere.  If you are currently struggling with drainage issues and would like a professional review of your situation, please contact us today on 0118 934 2958.

 

Image credit: estoril (cropped)

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