Assessment of Environmental Effects: Critique of the Cypress Mine Rehabilitation Plan Proposed by Solid Energy New Zealand Ltd
Solid Energy New Zealand Ltd are proposing the development of an open-cast coal mine in the upper Waimangaroa valley of the Ngakawau ecological district, near Westport. The mine rehabilitation scheme is expected to involve the removal and backfilling of overburden and soils from a 98 ha pit, an overburden placement area of 100 ha and new access road with a 12 ha footprint (Assesment of Environmetal Effects (AEE) Solid Energy 2003). The area of disturbance is specified as a north and south pit located on the valley bottom of the upper Waimangaroa and lower portions of the Mt William range, while the overburden placement area will be located near the existing St Pat’s Dam. The valley is recognised for its diverse and unique vegetation associations, related to unique ‘coal plateaux’ landforms and sandstone pavements (Norton 1997).
The objective of this essay is to outline the strengths and weaknesses the proposed rehabilitation plan possesses in relation to the criteria laid out in the Resource Management Act (RMA 1991) for the Assessment of Environmental Effects, and to assess this in light of current knowledge and research in this field.
Assessment of Effects
Under the Fourth Schedule, Section 1 of the RMA, matters that should be included in an assessment of effects on the environment include an assessment of ‘actual’ or ‘potential’ effects, with particular consideration given to;
“Any physical effect on the locality, including any landscape and visual effects”,
“Any effect on ecosystems, including effects on plants or animals and any physical disturbance of habitats”, and
“Any effect on natural and physical resources having aesthetic, recreational, scientific, historical, spiritual, or cultural, or other special value for present or future generations” (RMA 1991).
Those areas of particular relevance to the upper Waimangaroa in relation to rehabilitation of the site have been bolded, and can be summarised as effects to the landscape, effects to the ecosystem (plants, animals and habitats) and effects to natural resources having aesthetic and scientific value. Each area will be considered here individually.
Effects to Landscape: The AEE presented by Solid Energy only briefly addresses the value placed upon the unique landforms within the coal plateaux and Waimangaroa area, as outlined by the ‘Landscape Assessment’, prepared by Boffa Miskell Ltd. The assessment recognises the area as one possessing ‘high landscape values’, and concludes the effects to ‘the landscape and visual effects will be considerable’ and ‘ traditional mitigation measures will do little to lessen these effects in the short to medium term’. The consultants then recommend ways in which the rehabilitation of the topography could be reformed to mimic the surrounding relief, with the expectation that after long term revegetation has occurred on the site, very little of the disturbance will be evident. Although the importance of backfilling in a manner aimed at blending the modified landscape into the surroundings is commendable and necessary, it is the opinion of the author that the value of the landform in its natural state has not been sufficiently considered. This essentially is because there is no way that the natural state of the landforms can be rehabilitated. The geomorphology of the valley extends back thousands of years into the Quaternary, and the geology millions of years to the Eocene, its surface having developed in response to tectonic activity (evidenced in the distinctive fault scarp plateaux). The local rock type has been given the name ‘Brunner coal measures’, which encompasses a grouping of hard quartzose sandstones and coal seams overlain by mudstone and limestone (McEwan 1987, Norton 1997), the particular structure and composition of these being found only at this site, and at Mt Davy’s near Westport (pers. Comm. Norton 2004).
The long term rehabilitation aims of Solid Energy’s AEE are outlined as being “…to establish ecosystems similar in plant and animal species diversity and functioning to undisturbed ecosystems that help the constructed landforms blend into the adjacent landscape.”(page 1:2003). Although obviously the rehabilitated landforms are going to be of a ‘constructed’ quality, it is the use of the term ‘undisturbed ecosystems’ that is of concern. Given the unique quality of the landforms, it is the authors opinion that a rehabilitation standard of vague other ‘undisturbed ecosystems’ is not sufficient in this case, and recommend that the benchmark standard instead be the distinctive natural landform values of the area, as decided upon through future debate. More research needs to be done into the value of the areas geomorphology and geology in order to define a benchmark standard. It will then be possible to evaluate the credibility of disturbing it in such a way that rehabilitation to its original state is impossible.
Effects on the Ecosystem: Solid Energy have outlined a comprehensive rehabilitation plan for the flora and fauna of the area. As detailed later on, they have considerable experience in restoring vegetation to mined sites, and have developed new and innovative techniques in order to achieve this. However, mining at a site considerably alters the qualities of the soil and substrates, and plants used for regeneration of the site differ in composition from the original vegetative associations, due to the necessity of finding species that will survive, quickly colonise and provide nurse crops for future succession (Norton 1991, Ross et. al. 1995, Ross et. al. 1996, Davis et. al. 1997).
It is recognised in the AEE that areas of tussock and coal measures vegetation will be substantially smaller, and the author considers also that it is likely to be very different compositionally, even in the long term, from that which was originally present. The importance of restoring ecosystem interactions as well as components is outlined in Norton’s recommendations (1991) on restoration of indigenous vegetation to alluvial mine sites in Westland, and is broadly recognised in the literature (Spellerberg 1991).
Once again the value of the unique vegetation types, and more importantly their associations, needs farther assessment, as the associations present cannot be rehabilitated, being intimately tied to the particular landforms present. Norton (1997) outlines the specialised diversity of plant species related to the coal measures community type, which include endemic species evolutionarily suited to the environment. Solid Energy has undertaken a comprehensive baseline survey of the vegetation types and associations present, and this will provide useful information for ascertaining the value of the plant communities. Once again, benchmark standards specific to the site need to be ascertained.
Effects to Natural Resources: As outlined in the previous two paragraphs, the upper Waimangaroa valley and associated plateaux are seen as a considerable natural resource of scientific and aesthetic value. Baseline surveys on the flora and soils of the area have been conducted, and should prove a solid resource for assessing the value of the area, and also for designating benchmark standards by which rehabilitation goals can be set. The rehabilitation aims of the AEE which use an unspecified comparison of ‘undisturbed ecosystems’ is insufficient in relation to the unique properties the upper Waimangaroa valley possesses.
Mitigation of Environmental Effects
Solid Energy have outlined detailed rehabilitation plans for the expected 10 years of mine activity and 5 years post mine closure. These include utilisation of soil and vegetation from the disturbed site, and sequential timing of operations to maximise rehabilitation efficiency. Currently, new revegetation techniques are running at Stockton mine, a few kilometres NW of the proposed Cypress mine area. The site here is very similar in substrate and vegetation, however the microclimate is higher, more exposed, and less conducive to revegetation. The techniques trailed at Stockton include hand planting from nursery raised and wilding seedlings, direct transfer of large clumps of vegetation via heavy machinery, and seeding using techniques such as hydroseeding, fascining and slash. All of these techniques have particular advantages and limitations, and a combination of these is proposed for the Cypress mine. The author has no particular critique of any one of these techniques, except to point out their very recent development and the fact that many are under trial. The knowledge of the extent to which they will be successful for mitigating effects to the environment at Cypress is hindered by the lack of past replication of experiments at Stockton as noted by Theinhardt (2003).
The reason put forward by Theinhardt for the lack of success in rehabilitation trials was a lack of clear objectives, and this is also a serious critique of the plan proposed for the Cypress mine. She noted that “…clear objectives allow success or failure to be measured, ensuring that such projects are meeting their ecological aims.”( 2003 p87). Although Solid Energy’s proposal is comprehensive, it fails to specify quantitative standards, and the goals it intends to meet. The importance of baseline surveys play a role here, in allowing a sound knowledge of what is currently present in the ecosystem, for example the level of species richness expressed as the number of species present per unit area (Spellerberg 1991), or extent of seedlings, bird life and invertebrates (Phipps 2003). From this information, quantifiable standards can be derived and rehabilitation methods for meeting these criteria clarified.
One of the reasons Solid Energy does not present quantifiable objectives is perhaps because it is virtually impossible, given the current knowledge, to accurately estimate the success of revegetation techniques. However, quantifiable standards are an important criterion for deciding on whether activities of such magnitude should go ahead. The recent Kate Valley proposal as put forward by Transwaste, went through under the condition that certain criteria are met, and goals at 5, 35 and 300 year intervals were formulated. The 5 year outcomes are the most detailed and specify criteria such as the amount of area revegetated, percent survival rates and degree to which vegetation is growing vigorously (pers. comm. Norton 2004). It is recommended that in this case, a similar approach be taken with respect to specific quantifiable goals at intervals during and after the proposed mining operation.
Monitoring
Clause 1(i) of the Fourth Schedule of the RMA states that;
“Where the scale or significance of the activity’s effect are such that monitoring is required, a description of how, once the proposal is approved, effects will be monitored and by whom” (RMA 1991).
Monitoring is a vital component of ecological impact assessment, and the objectives, the methods, and the appropriate environmental indicators need to be specified at the outset (pers. comm. Norton 2004, Spellerberg 1991, Ross et. al.1996, Thompson and Thompson 2004). These enable management to assess the effectiveness of the techniques used for meeting the ecological objectives. Solid Energy do propose to commence monitoring, however they do not clarify what quantifiable goals they are attempting to monitor the success of (as related to the previous paragraph), the methods for undertaking this in a repeatable way, or the indicators they will use. Performance indicators are an important aspect of monitoring, and are being detailed in the Kate Valley rehabilitation scheme. The use of reference sites, representative as far as possible of the disturbed site, are also recommended, as these allow for natural environmental fluctuations (Phipps 2003).
Summary
The rehabilitation plan as proposed by Solid Energy for the upper Waimangaroa area is comprehensive, and reflects effective incorporation of recent research undertaken in the area of mine revegetation. It does, however, fail to address certain important issues. In relation to the assessment of the actual and potential effect on the environment, it does not sufficiently acknowledge the upper Waimangaroa valley’s scientific and aesthetic value as unique in its landform and vegetation associations, comparing it unsatisfactorily to other ‘undisturbed ecosystems’. Future discussion needs to be undertaken in relation to the natural value of the area to decide upon benchmark standards specific to the site.
The development of new techniques operational at Stockton mine are at the leading edge for New Zealand in terms of indigenous revegetation on coal mine sites. However, the success of the different techniques for the Cypress site is not certain, as trials done at Stockton have had poor replication. It is recommended that farther trials be carried out.
Quantifiable goals for rehabilitation at certain time intervals during and after mining are lacking, and need to be addressed using the benchmark standards developed in relation to the natural value of the site.
Monitoring of environmental effects is a requirement outlined in the Fourth schedule, but has only been alluded to in the AEE. Effective monitoring systems need to be put in place in relation to clear and quantifiable goals, with suitable reference sites and performance indicators identified.
References
AEE, Assessment of Environmental Effects, (2003) Cypress Mine: Resource consent applications and assessment of environmental effects. Solid Energy Coals of New Zealand Ltd.
Davis, M.R., Langer, E.R., and Ross, C., (1997) Rehabilitation of Native Forest Species After Mining in Westland. New Zealand Journal of Forestry Science. Vol 27, Iss 1:51-68.
Langer, E.R., Davis, M.R., and Ross. C., (1999) Rehabilitation of Lowland Indigenous Forest After Mining in Westland. Science for Conservation 117, Department of Conservation: Wellington.
McEwan, M., (1987) Ecological Regions and Districts of New Zealand. 3rd Revised Ed. New Zealand Biological Resources Centre, Publication No 5, part 3. Department of Conservation: Wellington.
Norton, D.A. (1997) The hidden coal plateaux of the Buller. Forest and Bird. May Issue: pg 27-33.
Norton, D.A., (1991) Restoration of Indigenous Vegetation on Sites Disturbed by Alluvial Gold Mining in Westland. Ministry of Commerce, Energy and Resources Division.
Phipps, H., (2003) Assessing Success of Restoration Plantings at Cape Foulwind. Msc. Forestry Science Thesis, University of Canterbury.
RMA, Resource Management Act (1991). The principle legislation for managing the use, development and protection of natural and physical resources in New Zealand.
Ross, C., Mew, G., Jackson, R.J., and Payne, J.J. (1995) Land Rehabilitation of Indigenous Forest Species. Science for Conservation 17, Contract Report. Department of Conservation. Wellington.
Ross, C., Simcock, R., Davis, M., and Langer, L., (1996) Mine rehabilitation studies on the West Coast. The Changing Face of West Coast Mining, The Australasian Institute of Mining and Metallurgy NZ Branch: 29th Annual Conference 1996.
Theinhardt, N., (2003) Plant Restoration at an Open Cast Coal Mine, West Coast. Msc Forestry Science Thesis, University of Canterbury, 104p.
Thompson G.G., and Thompson S.A. (2004) Adequacy of rehabilitation monitoring practices in the Western Australian mining industry. Ecological Management and Restoration, Vol 5, Iss 1, pg 30.
