There are no known waahi tapu sites or other known sites of significance on the site. However, through consultation with Mahaanui Kurataiao Ltd (MKT), a key cultural concern is managing potential adverse effects on groundwater quality. It has been determined that any potential adverse effects on groundwater quality will be minimised with no excavation to take place within 1 metre of the lowest recorded high ground water levels at the Site. Winstone will seek to continue engagement with MKT, Taumutu Rūnanga and Ngāi Tūāhuriri Rūnanga throughout the application process.
Most of the water used at the quarry will be for processing aggregate. The large majority of this water will either fall on the ground, or drain to silt settlement ponds, before discharging back to the aquifer. The silt settlement ponds also will take water and suspended silt derived from the natural strata. The water will be discharged through the base and sides of the ponds, and the sediments and silts will remain in the ponds. It may be necessary to clean out the ponds as silt and sediment builds up, and these materials will be spread out within the site. Given that the water and suspended sediment are derived from the natural strata within and beneath the Site, this activity is not expected to cause any adverse effects.
Winstone are not seeking consents to import cleanfill so water will only be used in relation to material extracted on the Site itself.
Truck washing will occur within fully bunded concrete pads. Truck decks will be cleaned using clean water with no detergents, therefore resulting wash water will primarily only contain fine sediment which will discharge to a sump, with overflow occurring to a soak pit. Body cleaning may involve biodegradable detergents and degreasers and could potentially pick up hydrocarbons. Therefore, this wash water will discharge to a sump and an oil-water interceptor, with the discharge water directed to a vegetated swale and then a soak pit. All water from sumps and soak pits will discharge to the underlying aquifer.
Water used for dust suppression will be sprayed at a rate to help bind surface sediments, and as it is used during dry, windy weather, it will primarily evaporate. It is not expected that this water will drain back to the underlying aquifer.
Stormwater from the roofs of buildings will either be diverted to storage tanks or discharge directly to ground as it will essentially be clean. Water from the internal sealed road will flow to roadside swales where it will be subject to first flush treatment prior to discharging to ground.
Office wastewater will pass through an on-site wastewater treatment system prior to discharge to a subsurface dripline system placed in the landscaped and bunded areas at original ground level. The discharge will occur in close vicinity of the office buildings.
Potable water for staff facilities will be supplied from groundwater.
The extraction and processing of aggregate and the movement of vehicles within the quarry site will generate dust. This aspect of the proposal is described in detail in the Air Quality Assessment at Appendix 15 of the Application. In summary, the most significant source of dust will be from the movement of vehicles along unpaved roads, stripping of overburden and the creation of bunds during dry weather.
During overburden removal and placement, the following mitigation measures will be implemented to mitigate the potential dust effects:
For the majority of the time the rock extraction and truck loading will take place below existing ground level, 500m+ from a site boundary, which will greatly reduce off-Site dust emissions. In addition, or when extraction and works are undertaken around or at the current ground level such as enabling works, there are three possible techniques that are commonly used at quarries to control dust from excavation and truck loading activities. These include wetting the material on the ground prior to the commencement of loading, the use of a fine water spray whilst loading is occurring, and / or the use of windbreaks to reduce wind velocities in the vicinity of the quarry.
The majority of the aggregates will be processed wet, which will result in little potential for dust emissions from the processing plant. Additionally, it is proposed to undertake the following mitigation:
The following mitigation measures will be the main techniques to control dust emissions from stockpiles, exposed areas, truck loading and transportation:
In addition to the visual monitoring programme detailed in the Air Quality Assessment at Appendix 15 of the Application continuous dust monitoring with telemetry will be undertaken at locations around the Burnham Quarry.
Quarrying requires the removal of soil to enable the underlying aggregate to be extracted. This will be undertaken in stages to minimise the time and the volume of soil required to be stockpiled. The removal and storage of topsoil will be undertaken with care to minimise effects on its structure, and ability to support vegetation.
Any soil disturbance (as part of proposed quarrying activities) is likely to result in disruption to soil properties such as soil compaction, loss of soil structure and degradation of soil aggregates during removal, transport and storage, and compaction of the soil material during placement. This can lead to impeded soil drainage (reducing air and water flow pathways in the soil), reduced soil water storage capacity, and reduced soil pores for biological activity.
Therefore, soil removal, management and replacement of soils as well as managing potential adverse effects on the surrounding environment will be undertaken in accordance with a Soil Management Plan (a draft is included in the Assessment of Soil Related Effects at Appendix 13 of the Application).
Noise levels resulting from proposed site activity have been modelled and assessed in the context of the Selwyn District Plan noise standards. In considering noise effects, existing background noise levels have been taken into account at key points around the site.
As a result of the assessment, the noise levels generated by operational activities, including vehicle movements on site, will be below the noise limits derived in accordance with the relevant guidance.
Notwithstanding the above, a number of good site practice measures are proposed to further reduce the risk of any potential adverse noise impacts and we are confident that the proposals have demonstrated that no significant noise intrusion will arise from the development.
For more information, please refer to the Noise Effects Assessment here.
The Site is well located on an arterial road that provides connections to State Highway1, Main South Road and State Highway 73 West Coast Road. This enables most travel to and from the quarry to occur on the state highway and arterial road network. Therefore, with local modifications proposed at the site access and to the route connecting the Site to State Highway 1 and the planned modifications to the State Highway 1 / Aylesbury Road intersection, it has been assessed that additional quarry traffic can be safely and efficiently accommodated within the existing transport network.
For more information, please refer to the Transport Assessment at Appendix 10 of the Application.
The landscape and visual assessment included in the Application examines the landscape character as a result of extracting gravel and installing plant and machinery, and the ability of the surrounding landscape to accommodate this change. It looks at the potential visibility of the development from various ‘viewpoints’ to help inform the design and layout.
Throughout its life the quarry operation will remain well integrated into the broader landscape, recognising the existing and proposed planting and that most activity will occur well below the existing ground level.
The greatest visual effect will be at the site entrance along Aylesbury Road at the commencement of the project, albeit becoming increasingly screened by planting and the relocation of processing areas to the floor of the quarry. Furthermore, the existing shelterbelt, proposed long-term bund, temporary stockpiles, and proposed areas of planting will ensure that visual effects from public viewpoints will remain effectively mitigated, and will be less than minor.
Views from private properties will largely remain unchanged as they will be truncated or entirely curtailed by the existing shelterbelt planting, long-term bund and intervening areas of planting including proposed native vegetation along the tops of rehabilitated slopes of the quarry, resulting in less than minor adverse effects.
For more information, please refer to the Landscape Assessments here and here.
The Burnham site has been subject to disturbance over many years, primarily through farming and forestry. While there is a small risk of disturbing the nests of migrating birds, Winstone will undertake pre-earthworks nesting bird surveys to minimise the risk of disturbance as much as possible.
For more information, please refer to the Ecology Assessment here.
As the site has a long history of agricultural disturbance, it is considered unlikely that pre-1900 archaeological material will be uncovered during quarrying activities. However, it is proposed to avoid damage to any archaeological site discovered during quarrying activities by applying an Archaeological Discovery Protocol.
For more information, please refer to the Archaeological Assessment here.
The Hazardous Activities and Industries List (HAIL) is a compilation of activities and industries that are considered likely to cause land contamination resulting from current or past hazardous substance use, storage or disposal.
HAIL activities have been identified on the site, all related to past agricultural use of the land. Broader sampling of soil surfaces outside of HAIL activity areas shows that likely indicator contaminants (i.e. heavy metals and organochlorine pesticides) are at background levels.
However, recognising that farming will continue across most of the site it is proposed that identified HAIL areas are subject to targeted detailed site investigations (DSI’s) as quarrying progresses across the Site. As such, potential adverse effects will be managed through an on-going process.
For more information, please refer to the Contamination Assessments here and here.
When each phase of the quarry activity has reached its maximum depth, soil will be re-established and farming activities will recommence, albeit at a lower elevation that is closer to the water table than is currently the case. This has the potential to impact water quality from neighbouring bores and is discussed in the Hydrology Report at Appendix 14 of the Application which is summarised below.
In terms of nitrates, the annual loss into the groundwater will remain largely the same as currently occurs, if the same farming land use were to continue, although the nitrate will reach the water table sooner than under the pre-quarry scenario.
E.coli from the current farming activity is most derived from animal excretions, which can migrate downwards through the soil and into the groundwater, particularly due to extra seepage that occurs during heavy rainfall events. During this migration from the ground surface through the sub-surface environment, E.coli number are reduced by filtration, desiccation, dispersion, dilution and natural die-off over time. The Hydrology Report at Appendix 14 of the Application concludes that post-quarrying there will still be sufficient E.coli removal to avoid adverse water quality effects on neighbouring bores.