Today I’d like to talk about Drainage issues around your home., both stormwater drainage from field grate and Soakage trenches.
The last few months have been very wet here in bundaberg, with many residents finding out where water ponds and creates a sloppy mess, as the rain continues and is predicted to do, for the next few months.
Avoid following issues at all cost.
Never, connect a drainage system to a roof water system as the head pressure of the roof water will push this water out onto the ground and flood the area you are trying to drain. If avoiding this option is not possible, there are a few things you can do that will assist in preventing the backflow of water from roof water onto your property. (only as a last resort)
1/ Connect the field grate as far as possible from the stormwater line as water will always exit via the easiest point of relief.
2/ when connecting into the stormwater use a “Y ” junction to assist in preventing the relief onto the lawn or area near the grate.
3/ where you require to change directions with the drain, avoid using a 90 degree elbow, instead use 2 x 45 degree elbows so as not to create unnecessary restriction of flow that will often make the water backup.
4/ Use a laser level, spirit level or Dumpy level to create slight fall or at least to avoid up and down in the drains that can trap water again forcing the water to back up again.
When backfilling under the stormwater lines always use sand to ensure there is no settling of the lines after the work is complete. Fill to the top of the drains then flood with a garden hose to ensure there are no voids under the drains. When selecting the size of the field grate always consider the likelihood of the quantity and size of any foliage that could potentially block the inlet. What I am saying is, avoid the use of fine easthetically pleasing grates that look pretty but will not handle any slight blockage by even tiny leaves.
In areas where you are installing slotted drain coil to catch soakage rather than groundwater, use a geotextile fabric (filter cloth) say 1m wide to lay in the trench and evenly up both sides, place an even amount before placing the drian coil, say 50mm. Place the drain coil, then ensure the coil is centrailised in the trench by placing drainage gravel around the drain coil. Level off the top of the gravel then fold across the grass the top of the filter cloth. Finally you can cover with soil and grass if necessary.
In areas where the drain coil need to be close to the surface you can just leave the filter gravel open to the surface without covering. This should only occur if it can be guaranteed that there is no likelyhood of siltation from the top. This system can be used on the edge of strip grates, paths and patios where the area falls doreictly to the collection point. When installing any soakage drains you must ensure the drain coil falls consistently to the point of relief.
I trust this helps you with some of the issues you may face, so you can avoid the pitfalls aften overlooked when installing such drainage.
Please contact the Lifestyle Solutions centre at 78 Mt Perry Road, North Bundaberg or call 4155 5500 should you require any assistance or advise your the challenge you may be facing.
by Peter Moller.