Boundaries affected by ground movement (Rule 18)

Note: this guideline is issued by the Surveyor-General under section 7(1)(ga) of the Cadastral Survey Act 2002 about the Rules for Cadastral Survey 2010 and is not legally binding.

The following information relates to rule 18 and defining a boundary affected by ground movement that is not in greater Christchurch.

The area of greater Christchurch is defined in section 4 of the Canterbury Property Boundaries and Related Matters Act 2016.

Application of Rule 18

Rule 18 applies to all surveys, except those in greater Christchurch, that re-establish boundary points and boundaries affected by ground movement.

Rule 18 sets out specific requirements relating to the re-establishment of boundary points and boundaries affected by ground movement.

These requirements either supplement the requirements of rules 1-15 or provide alternative requirements to those set out in rules 1-15.

This means that rules 1-15 must also be applied where relevant and where unaffected by rule 18.  Examples are:

  • Rule 18.2 (enabling class D to be applied to boundaries that would normally be class C) varies rules 3.2.3 and 3.2.4 which set other requirements for classes C and D.
  • Rule 18 does not include requirements on the evidence for defining boundaries as this is contained in rule 6.1 

Evidence for survey definition where ground movement

Rule 6.1(a) requires a surveyor to 'gather all evidence relevant to the definition of the boundary and its boundary points'.  Examples of relevant evidence where there has been ground movement may include:

  • the condition of witness and boundary marks and the ground conditions immediately surrounding these marks
  • visible evidence of a fault trace, slump lines, or liquefaction of soils
  • broken or cracked fencing or kerbs or building foundations
  • visible evidence of repair to, or reinstatement of, occupational features damaged by soil liquefaction or fault trace
  • photographic evidence including historical aerial photographs or photographs taken immediately before and after the ground movement event
  • local knowledge from occupiers, neighbours, and present or past owners
  • Local Authority records
  • news media articles
  • engineering reports.

Removal of old boundary marks

Where an old boundary mark has been determined as no longer marking a boundary point, the old mark must not be removed without first obtaining written approval from the Surveyor-General pursuant to s55(5) Cadastral Survey Act 2002. Approval can be requested using the ‘Survey Dispensation’ e-request.

Unproven marks where ground movement

A CSD may include an unproven mark where the mark has been affected by ground movement and it is not being used to define a boundary [r 18.3(a)(i)].  In this case, the Diagram of Survey must indicate each mark that is unproven [r 18.3(b)].

Horizontal orientation where there is ground movement

All surveys that meet the criteria of rule 4.1 (horizontal datum – orientation) must be in terms of NZGD2000.  This includes surveys where there is ground movement.

Horizontal connection where there is ground movement

All surveys that meet the criteria of rule 4.2 (horizontal datum – connection) must connect to a cadastral survey network mark. This includes surveys where there is ground movement.

Where differential ground movement has occurred between the site of the survey and the cadastral survey network mark, this connection may need to be made by field measurements as adoptions may not meet the required accuracy tolerances.

Boundaries affected by block shift

A boundary affected by uniform block shift (see rule 2) will have maintained its relativity with local survey marks and other physical evidence although its absolute geographic position will have changed.

In these cases, the local survey marks and other physical evidence will be able to be used in re-establishing the boundary in terms of that block shift [r 18.1(c)].

For vertical block shift, a reduced level (RL) defining a stratum boundary will no longer be correct.  The change in ground level on site must be determined and applied to the original RL.  In this case rule 18.1(c) applies.

Boundaries affected by deep-seated distortion

A boundary that has been distorted by deep-seated movement greater than the applicable accuracies set out in rule 3.3.1 (boundary points), rule 3.4 (water and irregular boundaries), or rule 3.5 (permanent structure boundaries), must reflect that distortion [r 18.1(a)].  This applies for horizontal boundaries and boundaries with a vertical component. 

Where shear and lateral distortion has occurred

Where a boundary has shear or lateral distortion (normally at a fault rupture):

  • a boundary that was formerly a straight line may now include one or more angles,
  • a boundary that moved with the earth will hold the same relationship to relevant physical evidence as it did prior to the earthquake.  An example is a boundary that coincided with a fence line will continue to coincide with that fence line.  Boundary points will still be defined in terms of close survey marks,
  • a water boundary or an irregular boundary moves with the ground movement in the same manner as points on a right line boundary.  

Illustrations C and D in Figure 1:  Examples of distorted boundaries below are examples of new boundary angles being created.

If the distortion in the boundary is less than the applicable accuracies set out in rule 3.3.1, the boundary should retain its original shape and the established hierarchy of evidence will apply.

Illustrations A and B in Figure 1:  Examples of distorted boundaries below are examples where new boundary angles are not created.

Examples of distorted boundary

Diagram showing examples of distorted boundaries
Figure 1: Examples of distorted boundaries

CSD requirements where a boundary has been distorted

Where an existing boundary has been distorted and new angles are created in terms of rule 18.1(a), the CSD must include:

  • a diagram showing information on occupation and physical features [r 18.1(b)(ii)],
  • a prominent notation on the Diagram of Survey and Diagram of parcels 'Boundary includes new angles due to deep-seated movement' related to the relevant boundary [r 18.1(b)(iii)],
  • information in the survey report regarding the definition of boundaries that have been defined by survey [r 18.4]. This will need to include the information relating to boundaries affected by distortion.

Boundary marking survey not permitted where boundary distorted

Where an existing boundary has been distorted by deep-seated ground movement and new angles created [refer rule 18.1(a)], a boundary marking survey defining that boundary is not permitted [r 18.1(b)(i)]. The new angles must be defined as part of a new parcel.

Adopting a boundary not permitted where distorted boundary

An existing boundary that has been distorted by deep-seated ground movement in excess of the applicable accuracies (refer rule 18.1(a)) is not permitted to be defined by adoption irrespective of rules 6.2(c)(ii) and 6.4.  The boundaries must be defined by survey as part of a new parcel.

Class C and D boundaries where ground movement

Where a boundary affected by ground movement meets the criteria for class C under rule 3.2.3, but may have been subject to distortion greater than the accuracy tolerances specified in rule 3.3.1 (boundary points), rule 3.4 (water and irregular boundaries), or rule 3.5 (permanent structure boundaries), then this boundary must be either:

  • accepted and be assigned class D [r 18.2(a)(i)], or
  • defined by survey.

The boundary is not permitted to be defined by adoption [r 18.2(a)].

A boundary that does not meet the criteria for class C [r 3.2.3] or D [r 6.3] must be defined by survey where distortion is greater than the accuracy tolerances specified in rules 3.3.1, 3.4, or 3.5. If the distortion is less than the accuracy tolerances, the boundary may be defined by adoption.

CSD requirements for accepted boundary where ground movement

Where a boundary is accepted under rule 18.2(a), the CSD must include a prominent notation on the Diagram of Survey and Diagram of Parcels 'Boundary not surveyed since ground movement' related to the relevant boundary [r 18.2(b)].

Last Updated: 31 March 2017
Authority: Surveyor-General - Section 7(1)(ga) of the Cadastral Survey Act 2002
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