Earthworks

Under the Christchurch District Plan, earthworks that are not associated with a subdivision or building consent must comply with certain requirements or resource consent will be needed. 

This includes works such as filling of old swimming pools, and any excavations or filling needed to create driveways, retaining walls, outdoor living areas, etc. 

To be permitted, earthworks must meet all of the following requirements:

• Not exceed the maximum volume and depth for the zone, as set out in the table below. 
• The gradient of the land where the earthworks will be carried out is no steeper than 1 in 6.
• The filling must consist of cleanfill only.
• Not be located within 5m of a heritage item or within a heritage setting listed in Appendix 9.3.7.2.
• Not be located within the dripline of a significant tree listed in Appendix 9.4.7.1.
• Soil compaction methods which create vibration must comply with a specific vibration standard and be certified by an engineer .
• In Residential zones, any use of mechanical or illuminating equipment is limited to between 7am and 7pm, and must comply with noise and light spill standards.
• In other zones, use of mechanical equipment is generally limited to between 7am and 10pm, and must comply with noise and light spill standards. 

Notes

This is only a summary of the main earthworks rules in Chapter 8.9 of the Christchurch District Plan(external link).

Depending on the property location there may also be relevant earthworks rules in other chapters, including:

• The zone chapter.
• Chapter 5 (earthworks in flood prone, slope instability and other identified hazard areas).
• Chapter 4 (contaminated land).
• Chapter 6 (earthworks within water body setbacks and within, and adjacent to sites of Ngāi Tahu Cultural Significance). 

Earthworks to repair land used for residential purposes that was damaged by earthworks are covered by a different set of rules, as are earthworks in the vicinity of the National Grid and electricity distribution lines. 

The maximum volumes listed in the table are for the total amount of filling and excavation within any 12 month period.  Volumes stated in m³/ha are applied as a ratio based on the area of the site. 

Effective erosion and sediment control is required to be implemented prior to beginning any earthworks.

These controls must ensure that surface water runoff and tracking of sediment from site work is prevented and managed appropriately to avoid the likelihood of damage, nuisance and contamination to roads, drains, waterways and other property.

Resource consents for earthworks usually include conditions requiring an erosion and sediment control plan (ESCP). These are to ensure that the work meets the requirements of the Council’s global stormwater network discharge consent from ECan.

The global consent requires the Council to ensure that a site-specific ESCP is prepared and implemented for all development sites that discharge to the reticulated network, before any earthworks or stripping of vegetation.

The ESCP must follow the principles and techniques in ECan’s erosion and sediment control toolbox for Canterbury(external link):

Low-medium risk sites

For example, flat land and simple hill sites.

• An ESCP must be prepared and implemented on-site prior to any earthworks starting. It doesn’t need to be submitted to the Council but must be prepared by a suitably qualified and experienced professional, held onsite and be available to the Council on request. 
• Advance notice needs to be given to our Resource Consent Monitoring Team of the start date, along with the name and contact details of the site supervisor, and confirmation that the ESC measures have been installed onsite.
• Any runoff must be controlled so that muddy water or earth doesn’t leave the site and enter the stormwater system or neighbouring properties. Muddy water is now defined as having a total suspended solid content greater than 50mg/L. 

High-risk sites

For example, near waterways, complex hill sites, and larger-scale works such as greenfield subdivisions and commercial developments.

• An ESCP must be submitted, accepted by our Subdivision Engineer and implemented onsite before any work starts. The plan must be prepared by a suitably qualified person and submitted, along with a design certificate (Appendix IV(external link) in IDS Part 3), at least five working days prior.
• If the site involves other environmental factors such as waterways or contaminated land, the ESCP must form part of an overall Environmental Management Plan.
• An Engineering Completion Certificate (Appendix VII(external link) in IDS Part 3) confirming proper installation of the ESC measures must be provided before works commence.
• Note: If an ESCP has already been approved as part of an ECan resource consent for stormwater discharge or earthworks, there's no need for it to be accepted by our Subdivision Engineer. 

Rule 8.9.3.a.iv exempts earthworks within the footprint of buildings if they have an approved building consent.

To meet this exemption, the Council will accept an undertaking from applicants that they will comply with the exemption at the time they carry out the earthworks. In other words, no earthworks will occur within the building footprint until the building consent has been approved. The building footprint is measured as everything within 1.8m of the walls of the building.

The written statement will be treated as evidence of compliance with the earthworks rules and needs to be included in the application for resource consent, building consent, or Project Information Memorandum (PIM).

Notes

• Any earthworks further than 1.8m from the building are not covered by the exemption so will require resource consent if they exceed the thresholds in Rule 8.9.2.1. This includes earthworks for retaining walls/structures that are not required for the structural support of the main building on the site or adjoining site.
• There are additional rules in 5.4.1.1 for earthworks within the Flood Management Areas.

Activities carried out on land that is contaminated, or potentially contaminated, must comply with the requirements of the National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (NES), unless a resource consent is obtained. 

Activities controlled by the NES include disturbance of soil (earthworks), soil sampling, removal or replacement of fuel storage system, subdivision, and changing the use of land (e.g. building a dwelling on vacant land, changing the use of a site from industrial to commercial).

Information about the NES is available on the Ministry for the Environment(external link) website. It explains how to find out if your land and the activity you are planning are covered by the NES. In addition, Environment Canterbury maintains a listed land use register of potentially contaminated sites(external link)

If you need further assistance you can also contact one of the Council’s Environmental Health Officers on 03 941 8999.

Where earthworks are associated with a building, they must comply with the Building Act 2004.  Where the work requires approval under the Building Act, an application for building consent or exemption from building consent must be made and approved before work can begin on the site. 

See Building Consents for more information on this process.

The Building Act requires anyone considering filling or excavating to protect land and other property from erosion, falling debris, slippage subsidence, inundation, alluvion and avulsion.

The Building Code requires any surface water collected or concentrated by buildings or site work to be disposed of in a way that avoids the likelihood of damage or nuisance to other property.