Damp or wet ground

Causes

Unusual rain event / Site unable to cope with heavy rain runoff

Blocked stormwater drain

Common

Listed under: plumbing, pipes, drains, Section, moisture, leaks

Cause

Unusual rain event / Site unable to cope with heavy rain runoff

Repair

  • improve site drainage by installing slotted drainage pipes under the surface. Flexible and solid proprietary products are both readily available. These should be installed in trenches lined with gravel and should slope downwards approximately 10 mm for every 100 mm of length. The excess water should drain to a soak pit or a stormwater system.
  • if constructing a soak pit, follow the guidance in New Zealand Building Code Verification Method E1/VM1. Be aware that construction of a soak pit may require a building consent

  • if human access is not required through the waterlogged site, creating a low-maintenance rain garden is another option using plants such as reeds and irises.

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Cause

Blocked stormwater drain

Repair

  • identify the cause and location of the blockage where possible

  • where rubbish or leaves entering the start of the drain have caused the blockage, rod the drain and try to pull blockage up – avoid pushing it further down

  • if the drain discharges into the street channel at the kerb, rod back up the drain from the street to clear the blockage, then put a hose in the drain near the start to flush the blockage out

  • if you think tree roots invading a drain may be the problem, this can be confirmed by a licensed plumber or drainlayer inserting a CCTV camera on a long cable into the drain. Cutting the roots away with a specialist power tool will offer a short-term solution. Digging up and replacing the affected part of the drain, or the whole length of drain, or the tree, can provide a longer-term solution

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