4. Proposed solution: national environmental standards (NES)

4.1  Introduction

4.2  Scope

The proposed standards would apply to the high-voltage electricity transmission network (the national grid), including the line supports (towers and poles) and conductors (wires), but excluding substations.

The first proposed standard covers the operation, maintenance and upgrading of transmission lines (referred to as transmission activities), but does not cover the construction of new lines. It presents a framework for managing the adverse effects of transmission activities, and lists those activities that do not have significant adverse effects as permitted activities (no resource consent is required). The proposal then sets out consent categories for activities that require resource consent. For example, a major upgrade would be likely to be a discretionary activity. This proposed standard would apply only to the line owner, and contractors carrying out work on behalf of the line owner.

The second proposed standard provides controls on activities adjacent to transmission lines, such as construction and excavation, which could have adverse effects on the transmission infrastructure and could put the transmission network at risk. This is referred to as the transmission risks standard. This proposed standard would only apply to third parties, and would not apply to the line owner or contractors carrying out transmission activities on behalf of the line owner. The proposed standard does not affect the operation of the ‘Trees Regulations’ (see section 2.4).

A summary of the key provisions is given in sections 4.3 and 4.4 below. Full details of the proposals for the transmission activities NES are set out in Appendix 4, and details of the proposals for the transmission risks NES are contained in Appendix 5.

4.3  Proposals for an NES for transmission activities

Structure of the standard

The proposed standard for transmission activities is based on recommendations made by a collaborative team of consultants with expertise in the identification and management of the environmental effects of high-voltage transmission lines, and the development and implementation of RMA controls. The proposed standard applies contains:

• a list of activities that are permitted (do not require a resource consent)
• terms and conditions to clearly define each activity and set thresholds of effects beyond which the activity would not be permitted
• consent categories to which activities default if they fail to meet the effects threshold
• consent requirements for activities that are not listed as permitted, or that fail a threshold test.

For activities listed as (or defaulting to) controlled, restricted discretionary or discretionary, a resource consent or designation would be required. For controlled and restricted discretionary activities the standard will list the matters over which the council will exercise control or discretion.

The proposed standard is generally more detailed than rules in district plans that manage the effects of electricity transmission, but it will provide for about the same level of management as in some plans. However, in some cases the NES will be more stringent (ie, provide a greater level of environmental protection) and in other cases the NES will be more permissive than rules in plans.

The proposed NES for transmission activities would override specific plan rules relating to transmission activities. Plan rules cannot be more restrictive nor more lenient than this NES. The only way in which plans can deviate from the proposed NES is to restate that an activity permitted by the NES is permitted, but with terms and conditions in the plan to control effects not covered in the NES. For example, a plan rule could say that painting transmission towers is permitted provided that the towers are painted a specific colour.

The proposed NES will be set out as a hierarchy compatible with the way many district plans currently deal with utilities. Figure 3 sets out the process for determining activity status and consent requirements under the proposed NES. If an activity is listed as permitted, it must meet the effects thresholds listed (terms and conditions). If an activity fails the effects thresholds, then the proposed standard will specify the status of the activity (generally as controlled or restricted discretionary). If an activity is not listed as permitted, then it may be listed as controlled or restricted discretionary (or in some cases discretionary). If an activity is not listed at all (but is still within the scope of the NES), it will be discretionary.

Figure 3: Determining resource consent requirements under the proposed transmission activities NES

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Section 1: Proposals for permitted activities: operation, maintenance and minor upgrading of transmission lines

This section lists general categories of activity that are permitted, subject to specific terms and conditions (for full details see Appendix 4). Activities that are permitted must not have significant adverse effects. The proposals for permitted activities (and the terms and conditions that apply) have been assessed to ensure there are no significant adverse effects. This includes the cumulative effects of undertaking more than one of the listed activities together, as is likely to happen in a transmission line maintenance or upgrade project. All permitted activities must meet specified earthworks and noise terms and conditions.

Transmission activities to be permitted include:

the operation and upgrading of transmission lines: operating at design voltage, thermal uprating and retensioning of lines, increasing line voltage

• towers, poles, foundations and structures:
  • tower washing, wet abrasive blasting and painting, subject to terms and conditions controlling discharges of contaminants and proximity to buildings and water bodies
  • strengthening, upgrading and replacing existing support structures and foundations, provided that any height increase does not exceed 15% and subject to limits on relocation distances
  • removal of existing lines
  • temporary structures
  • foundation dry abrasive blasting and painting, subject to terms and conditions controlling discharges of contaminants
• conductors and wires:
  • the addition of circuits where the line has been designed for an extra circuit (at present there are four lines like this)
  • alteration or replacement of wires, or the addition of wires up to duplex arrangement
  • the addition of up to two earth wires and communications cables
  • conductor maintenance
• hardware:
  • general maintenance
  • adding components (eg, hanger brackets, anti-climb guards, bird guards) and replacing components on support structures and conductors
  • signs (up to a specified size limit)
  • insulator cleaning and replacement
• earthworks associated with transmission activities, subject to controls on the volume excavated, sediment control, not disturbing historic heritage sites, and site restoration
• noise and vibration associated with transmission activities, subject to meeting construction noise and vibration standards
• vegetation trimming and removal, subject to conditions on landscape values.

Activities in the coastal marine area, in the beds of lakes and rivers, or that involve disturbance to known historic heritage sites such as wāhi tapu, cultural or archaeological sites will not be permitted activities. They are specifically listed as discretionary activities. Where an activity falls outside the scope of the permitted activity description (eg, adding circuits to lines other than the four lines listed) or fails the terms and conditions (eg, tower height increase exceeds the specified limit), then the NES will specify the consent category (generally controlled or restricted discretionary).

Section 2: Proposals for controlled activities: operation, maintenance and upgrading of transmission lines

The following activities are proposed as controlled activities (for full details see Appendix 4):

• replacement of towers or poles, with height increase as for permitted activities, but relocated outside the existing alignment by a set amount
• temporary line deviationand temporary line deviations which exceed the permitted activity terms and conditions
• trimming scheduled (ie, specifically identified in a district plan) vegetation
• new access tracks, or permanent deviations of existing tracks
• wet or dry abrasive blasting within 50 metres of (but not in) a water body or coastal marine area, or within 100 metres of a building or road
• earthworks associated with the maintenance and minor upgrading of transmission lines that do not comply with the terms and conditions listed in section 1
• noise which does not meet the permitted activity terms and conditions.

The matters the local authority may reserve control over could include:

• visual (for vegetation trimming)
• erosion control, discharge of sediment and revegetation
• heritage sites
• discharges and noise.

Section 3: Proposals for restricted discretionary activities: operation, maintenance and upgrading of transmission lines

Transmission activities that do not comply with the terms and conditions listed in section 1 for permitted activities or section 2 for controlled activities may be listed as restricted discretionary activities. Full details are set out in Appendix 4. Specific activities listed as restricted discretionary include:

• permanent deviation of a line
• replacing an existing overhead line with an underground line
• replacement of a tower or pole not satisfying the requirements for permitted or controlled activities
• the addition of conductors, earth wires, telecommunications facilities or signs, or the implosive jointing of conductors, which fail permitted requirements
• earthworks and tree trimming that fail permitted criteria.

Section 4: Proposals for discretionary activities: operation, maintenance and upgrading of existing transmission lines

Discretionary activities include:

• the undergrounding of transmission lines, or new access tracks, through scheduled cultural or historic sites, or through scheduled landscape or ecological protection areas
• work in the coastal marine area, or in the beds of lakes and rivers
• any transmission activities not listed elsewhere in the NES.

4.4  Proposals for an NES for activities that could put transmission lines at risk

Structure of the standard

The second proposed standard is based on key provisions of the mandatory code of practice for electrical safe distances (NZECP 34). It is based on an assessment of the key problems associated with third-party activities, the applicability of provisions in NZECP 34, and whether these can be effectively translated into an RMA framework. NZECP 34 controls activities that could endanger the transmission lines or be unsafe for the person carrying out the activity, which could be incorporated into a NES, including:

• excavation adjacent to transmission poles and towers
• erecting buildings and structures close to the lines
• stockpiling soil and debris under the lines
• facilities for launching boats (boat ramps).

The NES picks up the relevant aspects of the existing code of practice, and either prohibits them or proposes that a resource consent be required. Largely these are activities carried out by landowners on their own land. The assessment also examined whether risks to transmission lines could be reduced by incorporating additional provisions available under the RMA into the standard. The proposals for an NES therefore also include controls on subdivision (which generally requires resource consent in district plans). Damming and diverting water in a manner that could put transmission lines at risk is also being considered for inclusion in the standard.

The level of control proposed (see the explanation of activity types in section 4.3) is based on the level of risk, as follows:

• prohibited: activities that should never be contemplated at any place at any time because of the risk to the transmission line or public safety
• non-complying: activities where it is generally inadvisable to carry out the activity except in unusual circumstances
• restricted discretionary: activities that can generally be carried out provided controls are imposed to restrict the possible effects on the transmission line
• controlled: activities that can be carried out provided appropriate conditions are complied with.

The proposed standard sets limits on activities that can be carried out in the immediate vicinity of transmission lines. It is not intended that the provisions of this NES apply to the line owner carrying out the activities identified in the transmission activities NES.

For buildings and structures, two options are proposed. Both options provide for a prohibited activity zone around the wires, where any type of activity would put both the person undertaking the activity and the transmission line at risk.

• Option A follows the provisions of NZECP 34 closely, and would allow under-building.
• Option B provides for a zone within 20 metres each side of the transmission line in which a resource consent would be required for any building or structures.

Note that a definition of ‘building’ will be developed, which includes major structures and habitable buildings, but does not include minor structures such as culverts or sheds. In all cases it is intended that a district or regional plan can be more restrictive than the NES, and this will be explicitly stated. If an activity is beyond the scope of what is controlled by the NES (eg, an excavation at a greater distance than specified), then it would default to the provisions in the relevant district or regional plan.

Figure 4: Options for controls on buildings in the proposed transmission risks NES

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Proposals for standards

Activities covered by this proposed standard are categorised as follows (see Appendix 5 for details).

• Excavation near support structures (as per safe distances in NZECP 34):
  • prohibited: excavating to a depth of more than 300 mm within 2.2 metres of a pole or 6 metres of a tower, or creating an unstable batter that could put the transmission line at risk
  • restricted discretionary: excavating to a depth of more than 750 mm up to 5 metres from a pole or to a depth exceeding 3 metres up to 12 metres from a tower.
• Erection of structures near support structures (as per safe distances in NZECP 34):
  • non-complying: ranging from 2 to 8 metres for poles and 6 to 12 metres from towers, depending on line voltage 
• Erection of structures within a specified distance of transmission lines (conductors / wires):
  • Prohibited: within specified electrical safe distances around wires as per NZECP 34. The safe distances depend on the accessibility of various parts of the structure and vary from 1.5 metres distance from 33 kV lines for inaccessible parts of a structure (eg, steep-pitched roof), to 7 metres from a 220 kV line for accessible parts of a structure (eg, roof garden)
  • Option A (based on electrical safe distances in NZECP 34): between the inner ‘unsafe zone’ and an outer boundary around wires: restricted discretionary (note this allows under-building); the distances range from 7 metres vertically and 8.5 metres to the side of a short-span 33 kV line, to 11 metres vertically and 22.5 metres to the side of a long-span 220 kV line, allowing for conductor movement (note that 220 kV towers range in height from 20 to 50 metres)
  • Option B: zone in which resource consent required: between the inner ‘unsafe zone’ and an on-the-ground buffer distance of 20 metres from the centre of the transmission line: restricted discretionary.
    Note: an engineering survey is required in both options A and B to confirm the inner prohibited zone is not encroached upon.
• Deposition of material under transmission lines (as per safe distances in NZECP 34): prohibited.
• Subdivision within 20 metres of transmission line: controlled, with control reserved over the proximity of transmission lines to building platforms, and the ability to operate lines.
• Boat ramps within 9 metres of a line: non-complying (as per safe distances in NZECP 34).

Question 11: Do you have any comments on the activities proposed to be covered by the transmission risks NES? Is this the most appropriate way to manage these activities?

Question 12: Do you have any comments on the proposed activity types (prohibited, non-complying, controlled, restricted discretionary)?

Question 13: Which building option do you prefer and why? What should be the cut-off point for managing ‘buildings’ (eg, all buildings and structures, only inhabitable buildings)? What about bridges and other structures? How could this be defined?

Question 14: Are there any other activities that should be managed to prevent risks to transmission lines? For example, damming and diverting water could endanger transmission support structures. Is this adequately controlled in regional plans now, or are additional provisions required?