Earthworks

Accelerated erosion is often caused by clearance of woody vegetation and earthworks. Earthworks related to urban expansion, stream works and road works have the potential to damage water bodies if sediment from the work site is poorly managed. Sediment can damage our waterways’ ecology by:

  • Modifying or destroying instream, estuarine and coastal values (such as water quality and habitat); and
  • Affecting aquatic animals and plants due to smothering, change in food sources and interruptions in lifecycles.
In addition to ecology changes, sedimentation may damage water pumps, reduce domestic water quality or spoil an area’s appearance and affect the cultural values that tangata whenua associate with water. Earthworks can also destabilise sand soils in coastal areas which can cause unwanted effects associated with wind-blown sand.

Horizons monitors consents for earthwork sites across the Region to ensure sites are managed correctly in order to minimise the impact on water bodies when sediment leaves the site during rain events. A significant part of this job involves Horizons staff checking to ensure the site is being managed in accordance with an approved erosion and sediment control plan plus meeting other resource consent requirements.   
 

Resource consent requirements

You may need a consent if your activity will involve soil disturbance near streams, lakes, wetlands, coastal dunes, on steep land or if the area of disturbed land exceeds 2500 square metres per property per 12 month period. Earthworks that do not require resource consent are called ‘permitted activities’ and these require compliance with a set of permitted activity standards and conditions. To determine whether you need a consent, please call our consents team on toll free 0508 800 800 before getting your project underway.

Both situations require erosion and sediment control methods to be installed prior to, and maintained, during the earthworks activity. The guidelines (which can be used as best practice for permitted activites) and fact sheets below help design erosion and sediment control devices and an erosion and sediment control plan. There is also a resource consent application if you need one.

Erosion and sediment control guidelines

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This document sets the minimum standard for designing an erosion and sediment control plan as part of resource consent and permitted activities for earthwork sites.

Erosion and sediment control plan

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This document can assist contractors and consultants in preparing an erosion and sediment control plan for a site that recognises unique characteristics.

Factsheets

These factsheets can assist contractors and consultants to ensure sediment retention devices are designed and sized correctly. Some include best practice updates which improve device performance. We encourage contractors and consultants implement these updates in best practice when preparing and implementing an erosion and sediment control plan.

Decanting earth bund factsheet

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Working with concrete or asphalt factsheet

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Sediment retention pond factsheet

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Silt fence factsheet

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Stabilised construction entrance factsheet

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Silt filter log factsheet

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Catch pit protection factsheet

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Winter works application

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Most resource consents will require works to stop between 30 April and 30 September, unless written approval is obtained. A guideline has been produced to assist you with making your application to continue works through the winter works shut down period. 

Pre-construction checklist

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Most resource consents will require a pre-construction meeting with relevant parties involved in a project. This checklist is to assist you with topics to discuss and agree upon with Horizons staff members prior to commencing works. 

As-builts for control structures

Most resource consents will require erosion and sediment control structures to have as-builts completed, and to be certified that they have been constructed in accordance with the approved Erosion and Sediment Plan. These sheets are to assist you with the information required for the as-built certifications and can be downloaded by clicking on them.

Sediment retention pond as-built form

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Decanting earth bund as-built form

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Silt fence as-built form

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Diversion channel or diversion bund

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