Land Development Engineering

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  • 1.  Levels Between Subdivisions

    Posted 05-10-2017 09:35
    ​Could anyone advise how they handle fill at boundaries between subdivisions?

    Canterbury is a pretty flat region and we have a situation with quite a difference in height between 2 subdivisions. We are considering including a rule in the District Plan either stating that levels at boundaries must be maintained or stipulating that fill can only be installed to a max depth at the boundary. A condition would also the be included on the resource consent in a similar manner.

    My feeling is this will be quite restrictive in such a flat area and we will end up with a lot of non-compliances. Has anyone else got any similar rules in the DP or do you handle this kind of thing at engineering approval stage?

  • 2.  RE: Levels Between Subdivisions

    Posted 09-10-2017 08:43
    One should always be aware of the common law of support in that it is the responsibility of the downhill owner to support the uphill owner. By allowing filling to the boundary is imposing a considerable legal burden on the downhill owner unless easements of support are acquired with clear responsibilities outlined as to who is responsible for what.

  • 3.  RE: Levels Between Subdivisions

    Posted 11-10-2017 08:35

    In a subdivision situation I always insist the retaining wall is positioned entirely within the lot supported and not on the boundary.
    In a cut situation though, where the land to be supported is not part of the subdivision, it should be positioned entirely within the lot that required the cut and then the common law would apply with no argument.


  • 4.  RE: Levels Between Subdivisions

    Posted 11-10-2017 08:37
    ​Hi. I am not sure if I have ever seen rules within a District Plan controlling fill on boundaries.  I believe the Plan (in NZ at least) should consider the environmental outcomes rather than setting rules about fill on a boundary. We would normally consider the effect of placing fill on the boundary; how it will effect overland flow paths, land stability, long term access (future roads, development) etc. Also some Plans define the level at the boundary for height to boundary rules as the level at the time of subdivision, so adding fill may not always be of benefit.
    I also agree that having rules about the depth of fill at a boundary would be hugely difficult to monitor yet alone legally establish non compliance. In Auckland region filling at boundaries is often the best way to create suitable building sites.
    I suggest anyone interested in this subject attend the LDEG forum planned for early next year as we look at various means of developing land on varying terrain where I believe we will see fill on boundaries and other land development solutions.  In the meantime please keep providing feedback on this topic so we can share our expereinces.

  • 5.  RE: Levels Between Subdivisions

    Posted 11-10-2017 08:37
    ​Hi Clare
    Here at Taupo District, our residential earthworks rules only permit a ground alteration of +/- 500mm within 1.5M of the common boundary.
    If you want to do more you can apply for a resource consent, so Council get to assess it and decide if there are any affected parties and impose any reasonable rules. Outside the 1.5M setback you can do +/- 1.5M as a permitted activity. This seems to work well for us and seems accepted by the development community.
    Regards Roger Stokes, Development Engineer, Taupo District Council.

  • 6.  RE: Levels Between Subdivisions

    Posted 13-10-2017 08:57
    ​Thanks for your feedback everyone.

    The scenario I am dealing with at the moment is quite emotive. An unhappy ratepayer due to a retaining wall that has gone up in the adjoining property. Engineering wise it all checks out. Requirements around management of stormwater etc meant a retaining wall was logical and the house being built on the higher land does not cross the recession plane etc. Like Glenn we also look at how this effects overland flows paths and similar to Philip we require that the retaining wall is wholly within the property lifting the land.

    I think considering the location. . .the Canterbury Plains . . .people living here have an expectation that surrounding property will remain flat(ish) when in reality this is not the case. So at what point do you consider the neighbour an affected party?

    I somewhat struggle to get my head around this because if this were a hilly environment there would not be the same stigma.

  • 7.  RE: Levels Between Subdivisions

    Posted 16-10-2017 08:06
    From the private sector perspective, we see it too commonly where neighbours have this misconception that each property must redirect its surfaces flow to a street, and not maintain its natural flow path. We are daily educating the public that they cannot introduce retaining walls which redirect or concentrate sheets flow to a detriment to a neighbour.

    The most common issue we see where councils allow retaining walls even up to 600mm high, is there is rarely any mention of how to address where the aglines are drained too on low level sites. They typically are left to drain freely downstream and end up creating small water courses through to neighbouring properties causing slow erosion, which isn't picked up till a few years after installation.

    Mark Ibrahim
    Per ISC