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SubmissionsThe submission period for the resource consent applications lodged with Buller District Council and the West Coast Regional Council closed on Friday 30 January 2009. A total of 49 submissins were recieved from individuals and groups, with 31 submissions in support of the Project, 7 netural submissions and a further 11 opposing the Project (some in part only). The HDL team has prepared a response to the issues and concerns raised in the submissions as follows. (There is no particular order or priority in the following numbered points). 2. Uninterrupted public walking access from Stockton Mine 3. Historic electric coal tramway 4. Effects of the ocean outfall on the marine environment 5. Mitigation measures - flora and fauna 6. Modeling of dam breach - earth dams Vs. roller compacted concrete (RCC) dams 7. Generation capacity planning 8. Standards of site access at Granity 9. Quality of the aquatic/hydrological information 10. Life during the construction phase
Issue 1: The Darcy diversion should be included as a compulsory part of the Stockton Plateau Hydro Project (SPHP). Response 1: HDL cannot accept the Darcy Diversion being a compulsory part of the scheme. The Darcy Diversion is not required to manage the effects of any other activity covered by the consent. Construction of the diversion cannot be a conditional requirement on any of the other consents which have been sought. HDL anticipates that the Darcy Diversion will be included in the scheme if the Crown and Community accepts that the Project offers a complete solution for managing historic AMD and is prepared to contribute funding to achieve this. <Return to top> Issue 2: Maintaining un-interrupted public walking access from Stockton Mine gate through to the Repo Basin. (Note, HDL stated within the AEE that there would be a short period during construction and subsequent re-alignment that the track would be closed for public safety reasons). Response 2: The section of walking track flooded by Weka reservoir and blocked by Weka dams will be replaced with a walking track that follows the northern perimeter of the reservoir. The track will pass across or beneath the realigned haul road, up to the crest of the western saddle dam, along the saddle, main dam and eastern saddle dam to rejoin the existing track. An extension of the track to the south will take visitors around the southern perimeter of the reservoir to the power station tail race. Visitor information display and shelter will be located in this area. The new track route is shown in black on the following plan.
Figure showing access to the Repo basin during (blue) and following construction (black). During construction, a safe route will be established across the site as shown in blue on the attached plan. While mining continues at Stockton Mine, SENZ will control access through the CML and ACML and will be consulted on the route of the tracks and the new crossing of the realigned haul road to ensure public safety. SENZ has suggested that a pedestrian tunnel be built under the realigned haul road to remove the current hazard of crossing the haul road. In the long term, after mining ceases at Stockton Mine and the mine site reverts to the conservation estate, HDL will work with DoC to establish walking routes that extend from Weka visitor area, including a track from Weka reservoir to Mt William reservoir following the electric loco formation. <Return to top> Issue 3: The historic electric coal tramway was the first in NZ and is regarded as nationally significant - several submitters want it to remain undisturbed. (Note, within the AEE it is stated that the Project will affect approximately 460m of this historic formation). Response 3: It is impractical to construct Weka reservoir without relocating SENZ's haul road and destroying part of the formation of the historic coal tramway. It is not possible to comply with the archaeologist's recommendation (refer section 13.1 of Katharine Watson's report) not to inundate the formation. HDL believes the destruction of the section of the formation at Weka reservoir needs to be viewed in the context of the total remaining artefacts and in the context of the section of line that will not be disturbed by the Project, but will be protected and enhanced as a result of the Project's promotion. Reference to Project Plan C-007 will show that the archaeologist identified 86 way points (points of historical interest) over the remaining above-surface formation length of approximately 4 kms, (there are also extensive sections of formation underground that are not included in this summary). Construction of Weka reservoir western saddle dam southern abutment will destroy approximately 3 way points (3%). The haul road realignment has been selected to avoid destruction of way points. Realignment of the haul road and construction of the dam abutment will cross and destroy approximately 120m of formation (3%). Flooding of Weka reservoir will intermittently inundate a further 400m of formation (10%), which will not be physically disturbed by construction works but will be affected by infrequent inundation. Vegetation on this section of track will change from gorse and scrub to native swamp grasses. It is relevant that the sections of loco formation that will not be affected by the Project are currently in far better condition than the sections that will be affected. The AEE has proposed mitigation for the sections of the loco formation that will be destroyed. Artefacts will be recovered and incorporated into historic features at the Projects visitor facilities and at the Granity Museum. The remaining sections of formation will be recovered from the current state of neglect and can be incorporated into the walking tracks which will eventually link the Project facilities. The mitigation will be developed in consultation with SENZ and DoC, who both have plans for preservation of artefacts on the Stockton Plateau. HDL has included the archaeologist's report in the AEE, as submitted, despite HDL believing recommendation 13.1 of that report has been made out of context. HDL will invite a Historic Places Trust representative to visit the site on the planned Council site visit on 19 February 2009. <Return to top> Issue 4: Adequacy of information on the effects of the ocean outfall on the marine environment including extent of plume dispersion and effects from low pH and toxic contaminants. Response 4: HDL is consenting an ocean outfall and diffuser that will achieve ANZECC guidelines at the outer limit of the zone of reasonable mixing. Consents are being sought with conditions that define the performance of the outfall in terms of meeting ANZECC thresholds for discharge into a marine environment. Cawthron's report (refer to Appendix L) which assesses the ocean outfall states that "after passing through an appropriately designed diffuser the effluent should meet receiving water criteria under most operating conditions". Cawthron discusses the infrequent periods when criteria may not be met, and the option to cease discharge in these conditions. An appropriately designed diffuser will discharge effluent to sea water that is passing through the mixing zone through ports that are appropriately sized and spaced to achieve the required dilution. In practical terms, this means the length of the diffuser pipe that extends from the caisson at the end of the ocean outfall micro tunnel is long enough to accommodate the number and spacings of discharge ports necessary to achieve the required dilution in the rising plume. If actual effluent water quality is different to that predicted, through water quality modeling and field trials, the diffuser can be modified or replaced. Based on HDL's conservative water quality modeling results, Cawthron's analysis (Section 4.7 of their report) shows that the most likely operational conditions will require dilutions of less than 20:1. Section 4.2 of Cawthron's report establishes that a dilution of around 46:1 can be expected in the rising plume for a diffuser with the design specifications shown in table 5. A diffuser with these design specifications could be built without difficulty and would comprise a 50m length of PPE pipe connected to the outfall caisson, laid on the seabed on the line of the outfall, secured by rock rip rap. HDL's proposal is to specify and build an outfall diffuser so that the dilutions required to meet ANZECC threshold conditions are achieved in the rising plume. This will ensure that water quality at any distance from the diffuser will be within ANZECC guidelines, as further diffusion and mixing takes place. At the time the ocean outfall is constructed (anticipated to be 2012), the diffuser specification will be based on 3 years of field trials. Cawthron recommends that performance of the ocean outfall will be most reliably measured by continuous water quality monitoring in Weka reservoir. HDL proposes that the following should form conditions of consent: 1. The diffuser must achieve ANZECC guidelines for discharge to the marine environment at the boundary of the rising plume following reasonable mixing. HDL believes that submitters' concerns can be addressed by independent expert opinion which confirms that, in practice, the proposed conditions of consent are effective in resulting in the construction and operation of an ocean outfall which has no more than minor effects on the marine environment. The context for determining the conditions of consent in this case will need to take into account expert opinion that the adverse effects on the marine environment of the outfall under any conceivable operational conditions are not likely to be critical or lead to permanent damage to the marine environment. In addition, these conditions must take into account the expert opinion that not building or operating the outfall will lead to a continuation of permanent adverse effects on the Ngakawau River system and estuary. <Return to top> Issue 5: Several submitters requested that the mitigation measures outlined in HDL's flora and fauna consultant reports all be adopted, including comprehensive weed and pest control. One submission requested the development of appropriate management and monitoring plans. Response 5: HDL will undertake weed and pest control as defined by existing legislation, regional and district plans, and as required by conditions of access, to be determined by DOC, LINZ and SENZ. The AEE states that HDL will reinstate all vegetation disturbed by the Project. Land disturbance will be limited to the areas below the future reservoir surfaces plus access tracks to the reservoirs. HDL will make available to Stockton Mine, for direct vegetative transfer, all vegetation that will be lost to inundation within the reservoir footprints. HDL will control the weeds and pests within the immediate areas of its facilities (currently not controlled) as part of its ongoing maintenance of its facilities. HDL will undertake environmental enhancement around all its facilities in consultation with SENZ and DoC, the adjoining landowners. HDL expects that a condition of consent will be the requirement to prepare and submit to the Consent Authorities fauna and flora management plans, prior to resource consents being exercised. <Return to top> Issue 6: Concern was expressed over the fact that dam breach scenarios have been modeled for earth dams and with reservoir volumes significantly less than whats being proposed. It was requested that modeling of dam breach needs to be done for roller compacted concrete (RCC) dams at the reservoir volumes currently being sought to be consented, so that the public are made fully aware of potential risks. Response 6: HDL is seeking consents to dam. The AEE describes the environmental effects of the damming and determines that the physical structures that are built to achieve the damming and diversion are to be designed and built in accordance with NZSOLD high hazard requirements. The dam consents will not give HDL the authority to build any structure or to create any hazard resulting from the construction of such structures. The authority to build the dams and associated structures will be provided by a building consent, which will be issued under the Building Act 2004 and Building (Dam Safety) Regulations 2008. The application for the building consent will be made to WCRC who are required to pass the application to Otago Regional Council (ORC) for processing. Under the aforementioned legislation ORC has been established as the authority for assessing building consents for large dams on the West Coast. A building consent will only be issued if the risk to people as a result of dam break is sufficiently low to be considered less than minor. The consequence of awarding consents for the dam structures being applied for is that such dams cannot be built which would place the residents of Hector and Ngakawau, users of the Charming Creek walkway, the State Highway, or any existing assets at risk greater than they are currently exposed to from natural flooding of the Ngakawau River. Construction of the dams will reduce natural flood risk from the Ngakawau River by reducing the size of flood peaks. Natural flood risk could be reduced further by construction of flood defences along the Hector side of the Ngakawau River. HDL will be generating material from the Granity Tunnel which would be suitable for building flood protection works. HDL would construct flood defences if this was the wish of the community and consents were sought and obtained by WCRC. HDL does not propose the construction of flood protection works nor does it intend to seek consents for the construction of flood defences, as it is likely that the loss of amenity value from construction of such would outweigh the mitigation of flood risk, which currently has manageable effects, and will be reduced by the construction of the Project. <Return to top> Issue 7: One submission expressed reservations regarding HDL's claimed generation capacity for the SPHP and requested evidence of such. Concern was also expressed regarding planning issues of considering cumulative effects of the HDL Project in relation to a nearby hydro proposal and bundling of non-complying activities, where it was argued (incorrectly) that the SPHP has not been assessed against the objectives and policies of the relevant planning documents. Response 7: The basis for estimation of potential generation capacity is reported in Appendix I and has been independently verified by Buller Electricity Limited. The Mokihinui and Ngakawau catchments are sufficiently geographically separated so that there are no cumulative environmental effects between the proposed SPHP and the proposed Mokihinui power scheme. Never mind the fact there is currently no granted resource consent for the Mokihinui hydro scheme. Construction of the Mokihinui scheme would require a transmission line that passes over the Weka reservoir. Construction of the Weka reservoir/dam will not interfere with construction of this transmission line. The SPHP is embedded within the local network and does not require access to Meridian's proposed line. Options for transmission are discussed in the consent application. An independent assessment of the financial viability of the SPHP has been undertaken by Deloittes. The analysis has considered the economic effects of power from both Mokihinui and SPHP coming on-stream. SPHP is embedded within the local network and is viable with the construction of the Mokihinui scheme. <Return to top> Issue 8: One submission requested conditions addressing standards of site access at Granity and covering maintenance and responsibilities for the ocean outfall pipeline beneath the State Highway. Response 8: Requirements sought are covered by existing legislation and regulations and will be covered in access agreements. These do not need to form conditions of consent. <Return to top> Issue 9: One submission expressed concern over the aquatic/hydrological information provided in the application as not being up to date and not taking into account the current activities of SENZ, including addressing the long term management issues associated with the coal mining licence. Response 9: The water quality modeling undertaken by URS (refer to Appendix K) provides the detailed assessment of the effects of diversions and water quality in the reservoirs and outfalls. The modeling was jointly commissioned and funded by HDL and SENZ using the latest information available as of August 2008. The models are the current models used by SENZ and the scenarios for future land use on the Stockton plateau were agreed with SENZ. Information used in the assessment of the ocean outfall was the result of extensive searches of all data currently available. Through information sharing agreements with SENZ, HDL has access to the latest information. Despite Stockton Plateau having the most extensive environmental monitoring of any catchment in New Zealand, outcomes of the modeling show that the relationship between acidity and stream flow is not adequately established by the records. Records tend to have focused on low flow conditions. As a result current modeling is based on the conservative assumptions that the mean water quality conditions recorded will apply to all inflows into the reservoirs. To appreciate how conservative these assumptions are, reference is made to the latest recordings from recently installed telemetered sites that show that acidity reduces significantly during storm flows - the flows which are most important for hydro generation to fill the reservoirs. The attached figure shows how acidity reduced rapidly in St Patrick's Stream as rain set in during our open day on 17th January 2009. Acidity remained lower than the mean for many days after the event. HDL will undertake extensive field work over the 3 years from granting of consents to the time that the design of the ocean outfall diffuser has to be completed, to establish the relationship between flow and acidity that is implied in the attached graphs for all sites feeding into the scheme reservoirs. The water quality models will also be revised to model actual water quality inflows measured over 15 minute intervals. This will result in lower acidity (higher pH) and correspondingly better water quality at the ocean outfall than is being consented. HDL believes that the conditions that are being consented represent conservatively adverse effects on the environment. The conservative assumptions in the modeling ensure that actual conditions will be more benign than assumed.
Figures showing the dramatic increase in pH (dramatic reduction in acidity and increase in quality) in St Patrick's stream when flows increase, at the point the stream enters the proposed Mt William reservoir. This event was observed by visitors at HDL's open day. Improved water quality persists some time after the storm peak has passed. It is important to note when interpreting these graphs that the mean pH readings taken over set time periods (used in current modeling) do not take into account the volume of water that will enter the reservoir during during such a period. During high flows (times of low acidity) the volume entering the reservoir will be 10 to 1000 times greater than the water entering the reservoir over the same time period during low flows (high acidity). Water quality in the reservoirs, and hence at the ocean outfall, is determined by mixing of all inflow volumes. HDL believes that the next stage of modeling will show that water quality in the reservoirs, for most of the time, will be dominated by the water quality of high flows. The more acidic conditions predicted by HDL's current water model will only occur during extended periods of low flow. While extended periods of low flow do occur at Stockton, records show that they rarely exceed 27 days. Stockton is relatively unique in that rainfall depths are evenly distributed through out the year. <Return to top> Issue 10: Concerns from two family groups at Granity, one individual and one family group at Millerton, focused on perceived effects on their quality of life during the construction phase. Response 10: HDL will comply with all District Plan requirements to control construction effects to the specified levels provided in the plan. The methods of mitigating construction effects will take into account the duration of the effects. <Return to top>
This page was updated on 10-02-09 |
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