Submission by:
The Guardians of Pāuatahanui Inlet and the Te Awarua-o-Porirua Catchment and Community Trust
August 2020

Porirua City Plan Change 18 - Plimmerton Farm

Summary

The Porirua Harbour and Catchment Community Trust does not oppose the general intent of development proposals as provided for in the proposed Plimmerton Farm zone.

However, we wish to make submissions on issues relating to stormwater, drainage and related attenuation mechanisms such as swales and wetlands, and on identification and management of natural features, such as wetlands, on the area covered by the Plimmerton Farm zone.  The development of Plimmerton Farm and related management of it will have effects on the water and drainage systems and the ecology of the area.  All these effects will, in turn, affect the quality and ecosystem functioning of Te Awarua-o-Porirua Harbour.  GWRC’s Proposed Natural Resources Plan deems the harbour to have high ecological and cultural values.  In our view, it is imperative that the downstream water and drainage effects from this development are positive and enhance the catchment and harbour ecosystem, especially the Taupo Swamp.  Cumulative effects caused by construction, development and use need to be carefully managed and monitored in order to avoid and minimise adverse effects on the catchment and harbour ecosystem.

General

We have found interpreting what the provisions in this plan change mean for particular sites and areas is very difficult, if not impossible.  The planning maps are no more than illustrations and very general ones at that.  To make any on the ground sense out of the many provisions, a much finer grained set of maps is needed, or at least a provision such as that in the Porirua City Draft Reviewed Plan where overlay information at different levels can be applied to different areas. 

We see the limited information available from the various maps as a severe limitation on effective public participation, and in huge contrast to the PCC’s practice in its Draft Reviewed District Plan.

1  Introduction

We particularly support the purposes set out in the introduction to the zone to: 

• Provide for high quality open space in a way that incorporates and protects significant natural features within the site (Purpose 3); and 

• Incorporate freshwater management measures that provide for the recommendations included in the Te Awarua-o-Porirua Whaitua Implementation Programme (WIP) where they fall within the jurisdiction of Porirua City Council (Purpose 4). 

PFZ - O3 

We note that strategic objective PFZ-O3 states that subdivision, use and development in Plimmerton Farm will contribute to high water quality of receiving waters including Taupo Swamp, Taupo Stream, Kakaho Stream and Te Awarua-o-Porirua.  

We strongly support this objective.

SWwz-O1 

Objective SWwz-O1 (Water Sensitive Design) requires that subdivision use and development contribute to maintaining or improving the water quality of receiving waters. 

We submit that this objective be changed by omitting the word “maintaining”.  We consider that the definition of water sensitive design adopted for this zone precludes just “maintaining” water quality. 

We endorse the policies set out for Water Sensitive Design (SWpfz-P1) 

We submit that item 7 be amended to require that run off from impervious surfaces in Precinct D be limited and treated to remove contaminants and that this requirement be extended to all precincts. 

We note that the word “contaminant” is not defined in the definitions for this plan change.  It needs a definition that is the same as that included in the draft district plan which, in turn, is the definition included in section 2 of the RMA.

SWpfz-P2 provides for Hydraulic Neutrality. 

We consider and submit that this should be replaced by “net water positivity”. 

Net water positivity means that post development peak run off is less than pre-development peak flow rate, achieved by use of requirements from on site water management mechanisms such as stormwater collection/surge tanks of at least 10,000 litres per household and business, re use of this water on site for non potable uses such as garden watering and other outdoor uses, and perhaps toilet flushing, limits on impervious surfaces, use of swales instead of gutters for roads, and use of managed wetland treatment systems that discharge high quality contaminant free water. 

We consider and submit that adopting net water positivity will materially contribute to strategic objective PFZ-03 which states that subdivision, use and development in Plimmerton Farm will contribute to high water quality of receiving waters including Taupo Swamp, Taupo Stream, Kakaho Stream and Te Awarua-o-Porirua.  Further, it should reduce the demand for potable water supply and should result in smaller sized reservoirs and a lower capital investment by Porirua City in reservoirs for this development.

Section 7  Ecosystems and Indigenous Biodiversity 

The first sentence of this section says that it relates to Significant Natural Areas (SNAs) and Biodiversity Offsetting and Restoration Areas (BORAs).   This could be read to imply that this Section is limited to SNAs and BORAs.  But it also goes on to say that: 

“This section also includes provisions that seek to encourage the maintenance, enhancement and ongoing protection of the ecological function and biodiversity values of the site.” 

We take this statement to mean that Section 7 provisions apply beyond SNAs and BORAs and we endorse this approach and assume that Objective ECO-pfz-O3 covers this. 

If this is not intended then we submit that this interpretation should apply and therefore the plan change includes and requires the maintenance and enhancement of the ecological function and protective buffering of hydrological and ecological systems.

We support and endorse ECO-pfz-P1, the effects management hierarchy for Significant Natural Areas. 

ECO-pfz-P2 provides for subdivision, use and development in SNAs. We support the 8 items under this heading, and we can understand why subdivision boundaries will affect SNAs, but we wonder why use and development are included.  These concepts seem contrary to the objectives of SNAs.  As defined in Section 2(1) of the RMA, the concept ‘use” has some very deleterious connotations that would be completely inconsistent with the purpose and function of SNAs. 

We submit that “use and development” should be removed from this provision or specifically defined in a way that clearly and significantly limits their effects on SNAs.  We note there is no specific definition of these terms in the definitions section of the Plan Change.

We support ECO-pfz-P3 and its provisions covering Biodiversity Offsetting. 

ECOpfz-P4  We submit that, given ECO-pfz- P2 (5) states that building platforms and vehicle accessways should be avoided in SNAs, it is inconsistent that public roads should be provided for.  We consider that, except in exceptional circumstances, public roads should be prohibited from traversing SNAs and where they do, stringent provisions should be applied to reduce their footprint (such as single lanes, low speeds, and bordering swales or other measures to manage and treat stormwater to ensure any that enters SNAs is contaminant free).

We support ECO-pfz-P6 to avoid the establishment of new plantation forestry within SNAs and BORAs 

8   Earthworks 

We support EWpfz-O1 and the following policies EWpfz-P1 and related zone provisions 

We submit that it is critical that these provisions, and especially the sign off and application of Erosion and Sediment Control Plans, be followed, monitored and enforced by the Council. Any non-performance to these requirements will have severe and possibly irreversible consequences on the wetland ecosystems in the Plimmerton Farm zone and, especially, on the Taupo Swamp. 

One of the sources of sediment entering the harbour is caused by run off from building platforms.  As yet there is no or very little experience with removing soil and changing the landform in Plimmerton farms.  For this reason, we consider there should be a provision requiring small scale tests to be conducted, monitored and assessed in any area before it is opened up to wider earth movements. 

There are a number of non specific words embedded in these provisions with such terms as minimise (3a) (3b) , practical minimum (3f) appropriate (3g) reduce (3h) as soon as practicable (3i) , where appropriate (3j). These terms are also used elsewhere. 

Whilst the use of these terms is understandable, they require site related interpretation and underscore the need for Council monitoring and enforcement.

10    Subdivision 

PFZ-O4  We submit that this objective should be amended to read: 

“Significant Natural Areas and Biodiversity Offsetting and Restoration Areas are protected and provided for through subdivision as are the maintenance and enhancement of the ecological function and protective buffering of hydrological and ecological systems” . (Added words are in italics).

SUBpfz-P1  We submit that this policy should amended to read: 

3   Provide for built development to occur outside any Significant Natural Areas and any Biodiversity Offsetting and Restoration Areas and have no adverse effects on the maintenance and enhancement of the ecological function and protective buffering of hydrological and ecological systems that fall within or adjacent to an allotment.  (Added words are in italics)

Subpfz-P5  We submit that the introduction to the policy provisions should be amended to read: 

“In respect of a subdivision of an allotment that includes a Significant Natural Area or Biodiversity Offsetting and Restoration Area require the preparation of a Land Management Plan to be approved by the Chief Executive, Porirua City Council, before work begins, and that would have no adverse effects on the maintenance and enhancement of the ecological function and protective buffering of hydrological and ecological systems”  (Added words are in Italics)

The policy does not state how the Land Management Plans are to be assessed and who approves them before any work begins. We are particularly concerned that in Precincts A, B and C that heavy reliance is being placed on private landowners being required to manage watercourses and wetlands.

PApfzStandards, PBpfzStandards, PCpfzStandards and PDpfzStandards

We submit that an appropriate Standard be inserted in the provisions for reach precinct covering the obligations of landowners in managing watercourses and wetlands.

We note that the plan showing the Open Space networks in the draft PF Precinct Plan (at p12) states that certain areas will be “privately owned and managed ..and protected by covenants” Nowhere, in the draft precinct plan nor the proposed Plan Change is there any indication of the nature of these covenants, the obligations within them and whether compliance will be monitored and, if so, by whom.

In our view, this is a serious gap in the future management of protected areas. Considerable time, effort and resources have obviously been entered into understanding the hydrology of the land and how best to manage it (see Attachments 6 and 9 to the Plan change especially). Nevertheless, apart from a specific area of wetland to be vested in the Porirua City Council there is no clear, certain and unambiguous policy, rule or standard for the management of these “private” wetlands.

In essence, the ongoing protection and management of the non-vested protected areas has been privatised and unknown and unspecified obligations placed on landowners. There are no incentives in the Plan Change for landowners to manage these areas in manner which reflects the wider objectives of the Plan Change.

Policy PCpfz-P1 

This policy requires the maintenance, protection and enhancement of the natural, landscape and open space values of: 

1          The Kakaho Special Amenity Landscape;

2          Significant Natural Areas

3          Biodiversity and Offsetting Restoration Areas.

The Kakaho Special Amenity Landscape is defined, in PCpfz-Appendix-1 as including: 

• An open rolling landform;
• A predominantly unmodified landform;
• Primarily managed as pasture;

It goes on to say that: 

• The landform remains largely open and intact…;
• The folded landform creates a vivid “rumpled blanket” effect;
• Despite extensive pastoral use, the landform remains relatively natural with limited modification;
• Distinctive valleys and open rolling tops highlight bold changes in shadow and light;
• It provides a highly recognisable local backdrop;
• Changing light on the hills...are often the subject depicted in paintings and are frequently photographed as part of the backdrop to Pauatahanui Inlet.

 We submit that the Kakaho Special Amenity Landscape attempts to protect and enhance a landscape that is incompatible with ecologically sound catchment and water quality values and, if it means the continuation of an open pastoral landscape, then this will have adverse effects on the condition of the Pauatahanui Inlet. 

Experience in the area shows that small scale rural-residential activities often fail to manage the land effectively.  Weeds and pests are introduced and animal management can be variable.  It would be preferable to encourage landowners to plant indigenous vegetation which, over time, will significantly reduce sediment and contaminant in flows to the Inlet, and will be far less costly to manage and maintain. 

The “downside” is that the “light on the hills” value will be progressively changed, but we see this as a small price to pay for longer term ecological benefits.

We therefore submit that the Kakaho Special Amenity Landscape and references to it in the policies and rules be removed from the plan change and substituted by changes to Ppfz-P1 as follows:

Maintenance, protect and enhance of the natural and ecological values of: 

1          Significant Natural Areas

2          Biodiversity and Offsetting Restoration Areas.

3          Indigenous vegetation and revegetation. 

by requiring development to be located in accordance with the Precinct C Plan (which may need some revision)

Other changes should then be made to policies and provisions such as:

PCpfz-P2

3          The use or development avoids significant adverse effects and avoids, remedies or mitigates any other adverse effects that may cause potential erosion, sedimentation and contamination from chemicals, pathogens and nutrients that could affect the soil, and enter wetlands and waterways.

PCpfz-P3

“3         Areas of indigenous vegetation are retained and, where practicable, extended across the non developed landscape;

We strongly support item 4 in this policy which encourages retirement and revegetation with indigenous vegetation.