Building over Pipes

Wastewater and stormwater pipes

If you are thinking about or planning a new building project, a garage, a sleep out or an extension to your house you should check to see if a Hamilton City Council wastewater or stormwater pipe runs through or near the area that you wish to build within.

This is important as any structures built over the pipes are likely to apply loading to the pipelines or disturb fill material around the surrounding areas. These factors could result in pipe failure and subsequent wastewater or stormwater blockages and flooding.

Such incidents can affect nearby structures and cause significant damage to personal property and stress to people’s day-to-day lives.

Even if there are pipes running through the area you may still be allowed to build over wastewater or stormwater pipes if conditions are suitable. These include structural designs that meet Council’s requirements.

Wastewater and stormwater manholes and service pipes (connections) cannot be built over in any circumstance, please contact Council's City Waters if you wish to discuss any alternatives such as relocation of manholes or connections.

Find more information on our stormwater and wastewater pages.

The process

Step 1: Identify the Council assets (pipes/manholes/catchpits/service connections) that are located in the immediate area.

You can do this by visiting Council at Garden Place and for a small fee receive a copy of the service plans from Building Control Unit (ground floor) or by accessing the wastewater/stormwater plans for the area in question by viewing service plans online

Step 2: Detailed investigation

If you have identified Council assets located on your proposed building site, further investigation will be required.

This investigation will accurately identify where the assets are located in relation to your proposed building site and the depth and current condition of the assets. This is done by CCTV inspection of the pipe and by accurately marking - this is normally done by pegs from boundary to boundary - on the site, the location of the pipe, where it is laid and any connections attached to the pipe.

You may also apply for the CCTV inspection prior to lodging your building consent by visiting City Waters level 5 of the Council's offices in Garden Place.

Step 3: CCTV results and building structure design

It is important the pipe is in good condition. If not, the required repair must be carried out before any building activities commence on site.

Council will endeavour to undertake any repairs to accommodate your building programme. However Council reserves the right to carry out the repair works at a time that is most suitable. Your Building Consent may be delayed until the repair work is completed.  

If the pipe is in good condition you will be granted permission to build over it. You will need to engage a structural engineer to design a foundation that places no loading on the pipe.  The final design must be approved by Council.

City Waters mandatory conditions for design

No manholes or service connections are located under the intended building or structure. Adequate clearance must be allowed for maintenance activities. The distance can be determined when the depth of pipe is known.

The intended building is specifically designed so that no structural load is placed on the pipeline. 

If piling is required, all piles must be located no less than 1.5 metres clear of the outside of the pipeline. 

All piles from within 5 metres of the pipeline must be drilled to at least one metre below the 45 degree influence line of the pipeline before pile driving can commence.  Infrastructure Technical Specifications

Step 4: The building process

Once the design is approved you can then proceed with lodging your Building Consent with the Council's Building Control Unit. If you have already lodged your Building Consent prior to the CCTV inspection the results of the inspection need to be obtained before your consent is processed.

Further information

A CCTV inspection is a vital tool in minimising damage to public wastewater/stormwater networks while allowing people to build where they wish to.

A CCTV inspection is required for the following:
  • Where the proposed building platform is within five metres of any public wastewater/stormwater pipe
  • Where there is uncertainty regarding the location of a wastewater/stormwater asset in relation to the proposed building site

If you are unsure about whether you require a CCTV inspection contact City Waters for further information.

Page reviewed: 10 Nov 2017 10:22am