After an extension to the house which included a large back deck, Lisa and Rob were left looking at a backyard that could only be described as a bit of an eyesore. Years of poor drainage had left them despairing. The low lying Tarragindi yard is hit regularly in summer with downpours turning it into a swimming pool over 30cm deep in places. Even worse for them, their children and pets, the ground would stay boggy for weeks, making play and maintenance a nightmare.
After a long consultation, a two fold solution was proposed- firstly, divert the sheet flow storm water coming down the gully from the neighbours’ gardens into an existing drain. Secondly to make the back yard lawn area free draining after rain events. And additionally to all this, to make the garden nice on the eye again.
Firstly to divert the sheet flow, an intercepting diversion drain was created using 100mm agricultural pipes set in recycled concrete gravel. This was then lined with a thick rubber edge to prevent tree roots and to hold back water during large rain events. This strip drain discharges into an existing grated drain that had previously became blocked with leaves after every downpour. To prevent this from happening again a gabion structure was created around the drain using paving stones re-purposed from the site. Any leaves that block the drain now have a much larger ‘sticking surface’ that should ensure water has more entry points into the drain.
Secondly to cure the boggy lawn problem a 50-100 mm sandy underlay of organic topsoil was underlain over the existing ground, with re-profiling to ensure drainage to the southwest corner of the house, where the water can enter an existing drain or head on down the driveway. This was reinforced with a herringbone pattern of agricultural pipe drainage to capture any lingering sub surface water and drain it away, similar to the manner that is used on many golf putting greens and tees.
Finally to improve the overall look of the yard, edges were added and softening gardens established for aesthetics, drainage, ease of maintenance and shading gardens. This included a free standing timber wall, constructed to conceal two previous retaining walls which still serve a purpose to contain water runoff from surrounding properties. The wall offers seating opportunities and adds clearly defined edges to the lawn, and ease of maintenance with the support posts concealed behind the wall giving the lawn mower a clear run along the edges. They also complete the look and make this space one that can be enjoyed as it should be for years to come. Now all that is needed is that downpour!