About earthworksMō te Ahuwhenua

Activities like excavation, drilling or earthworks can affect the environment, other people and properties.

Earthworks

Earthworks can be described as any activity that disturbs soil, earth or land surfaces.

Stability and safety are key considerations with excavation or fill projects, which range from driveways and retaining wall excavations to quarries and earthworks for major subdivisions and multi-storey buildings. These activities are therefore likely to need a resource consent. There are Napier Operative District Plan rules around earthworks to ensure safety, and prevent adverse effects or damage to the environment. Resource consent applications will be considered under both the Operative District Plan and any relevant sections of the Proposed District Plan until the Proposed District Plan becomes fully Operative. During this period, you should check both the Operative and the Proposed District Plans to fully understand the planning rules for the district. Please note that there are rules related to earthworks in the Proposed District Plan which took immediate legal effect when the plan was notified.

If you would like to discuss your earthworks plans before starting, you can request pre-application guidance by phoning us and asking to speak with a duty planner.

Earthworks on contaminated land or by waterways

If a site has contaminated land, or is close to waterways, it is even more important that earthworks are done carefully and properly.

Land may be contaminated if it was previously used for a hazardous activity or industry. View a list of these activities and industries on the Ministry for the Environment website.

If you are planning to dig or disturb contaminated land, for testing or for any other purpose, please call us on 06 835 7579 and ask to speak to the duty planner.

Earthworks conditions

An earthworks resource consent looks at geotechnical aspects of your property and sets conditions to help you achieve suitably engineered excavations and fill. It also ensures that earthworks are undertaken in a manner that prevents or limits sediment discharge, thereby protecting the freshwater and marine environments.

Earthworks monitoring

We monitor earthworks projects to ensure safety and compliance. Some of these conditions require protection measures to be set up before you start your earthworks.

Whether you have a small building site or a large development, it is important to have erosion and sediment controls measures (such as stabilised entranceways and silt fences) in place before you start your earthworks.

Soil erosion, sediment and dust from earthworks

Earthworks can result in erosion of exposed surfaces, which produces sediment and dust.

Sediment has a direct impact on waterways and organisms living in these environments. It alters fish habitats by:

• smothering aquatic life
• damaging fish gills and mouthparts
• increasing temperature and turbidity (cloudiness of the water)
• preventing light penetrating the water.

Sediment also transports other pollutants into waterways, such as:

• lead
• hydrocarbons
• agricultural nutrients
• other toxic substances.
  
  

Increased risk of soil erosion

The risk of erosion increases if land:

• has little vegetation on it
• is steep
• is on the bank of a river or lake
• is disturbed
• has erosion-prone geology (for example mudstone or pumice)
• is under pressure from high stock density or machinery
• is in an area of high and intensive rainfall.
  
  

How to control sediment and reduce soil erosion

Before you start, we recommend you seek advice from a qualified practitioner for your specific project to ensure you have adequate and site-specific sediment and erosion controls.

You can reduce the harmful effects associated with sedimentation by controlling erosion.

This can be done by incorporating appropriate erosion and sediment controls as an integral part of your project. This will include:

• minimising areas to be disturbed
• staging earthworks by undertaking earthworks in small areas over time
• stabilising exposed areas quickly and keeping as much existing vegetation as possible, especially on steep slopes or areas close to watercourses
• using appropriately designed sediment devices to retain and treat sediment before its discharged.

Both the landowner and contractor undertaking the earthworks need to be aware of the importance of erosion and sediment controls on their site.