Retaining wall Wellington, Concrete retaining wall Lower Hutt

Retaining wall removal in steep or restricted areas
Where access is steep or confined, then it is unlikely that any heavy machinery can be used, in which case the wall has to be dug out by hand, in order to expose the footing or foundation.

The wall would typically be sawn into appropriate sized sections by concrete saw or broken up by electric breakers. The spoil would then be usually transported by hand or wheel-barrow to skips, or to a site where it can be loaded out by digger and truck.

If access permits, one of the diggers would pull over or break up the wall with a hydraulic breaker, load the spoil onto the motorised wheelbarrow and transport it to either a bin or truck.

However for larger and more heavily engineered walls, particularly when the concrete is to be removed offsite, it is generally more efficient to simply cut the complete wall up.

This process is faster, readily deals with the steel reinforcing that otherwise holds the concrete together and greatly assists in the handling of the many tonnes of concrete involved.

The advantage for the customer here is that by using Able Contractors the wall can be sawn strictly as required while the wall is actually being pulled apart into an optimal size for efficient handling by the diggers. This is based on the old but well proven - suck it and see - policy.

Replacement of concrete retaining walls

The replacement of existing retaining walls generally requires a permit from the appropriate local authority, which does require suitable plans drawn up an engineer.

However in the case of small and low level retaining walls of up to 1.5 metres in height your local Council is unlikely to worry unduly about a permit.

However, if a new wall is being built or where significant excavation or earthmoving is involved, there are significant restrictions to the volume of dirt and depth that can be shifted without a permit or consent. It is the customers responsibility to check for and obtain the consent, if one is required.

The key consideration in designing and building a stable post and plank retaining wall is the assessment of the bearing capability of the soil. This type of structure generally fails due to either inadequate allowance for poor or varying soil load bearing capacity, or due to lack of or poor drainage behind the wall.

It is readily apparent that walls retaining ground subject to significant runoff, should have suitable drainage built behind them.

At times however, not enough allowance is not made for soft, wet or poor soils which typically provide little weight bearing capability and lateral stability.

This situation is common where residential sections have been leveled on a cut and fill basis.

On sites where gullies and slopes have been built up many years ago, while the upper ground surface may appear well compacted, lower profiles may well vary in terms of the nature of the fill and invariably in the extent of compaction.

As a general observation, it may be helpful to use a contractor who has the intelligence and commitment to check with the engineer and or client, rather than one who continues on regardless on the basis that he was following the design to the letter and that if the wall shifted it was not his fault.

Once a wall shifts, it obviously becomes very expensive to rebuild or reinstate it. Customers would not, I expect, be very keen to pay twice for the same wall.