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Overview

Introduction

This document sets out a proposal to develop a small scale run of the river hydro-electric power generation plant within the Parapara River watershed in Golden Bay, Nelson province. The current electrical power supply market shows the potential for the development of additional renewable generation capacity. The scheme is anticipated to have an electrical generation output of up to 1.5 MW using one multi-jet turbine. 1.5MW is sufficient electrical capacity to provide power to over 300 homes.

The land has Reserve status and is part of the Conservation Estate managed by the Department of Conservation (DOC). In order for this project to be advanced a number of approvals are required from Government Departments, compliance with the Resource Management Act administered by the local authority, in this case the Tasman District Council (TDC), and the New Zealand Historic Places Trust. This report forms part of applications to each of the organisations from which consent is required.

The key feature of this scheme is the refurbishment and the reconstruction of existing infrastructure. These are mostly relics from hydraulic gold mining activities in the late 19th and early 20th centuries initially owned by the Parapara Hydraulic Sluicing Company from 1892. In addition to this reinstatement, the proposal requires the construction of a small building to house the power generation equipment and a section of electric power transmission line.

During the construction and subsequent operation of this scheme a number of effects on both the environment and on historic values are anticipated and this report includes the results of specific investigations that identify these and suggest methods of elimination, or means by which mitigation of these effects can be achieved.

Locality and geologic setting.

The Parapara River is the third largest river discharging directly into Golden Bay after the Aorere and Takaka Rivers. The catchment has an area of 37 square km. and lies to the east of the lower reaches of the Aorere River bounded by the Parapara Ridge eastwards, the Queen Ridge and the Slate River to the south and various smaller creeks draining the goldfields directly into the Aorere to the west.

The catchment is contained in what are Ordovician age meta sediments included in the Takaka Terrain and separated from the Buller Terrain by the nearby Anatoki Fault. This fault is responsible for the current juxtaposition of these two distinct sedimentary basins / zones. This now complexly folded and faulted sequence was a late Cretaceous early Tertiary erosion surface, the so called Waipounamu Erosion Surface. Subsequent rocks deposited in the later Tertiary sea transgressions have mostly been eroded off within this catchment. Remnants remain nearby, notably the Takaka Limestone at Devils Boots, t he Aorere Caves and in the lower reaches of the Parapara River.

Tectonic contraction in the Miocene period tilted this block to the west towards the Wakamarama Fault on the western side of the Aorere Valley however the present northerly trending Parapara River course was already inscribed into the Ordovician basement which was then once again exposed. The colluviums, clays and conglomerates remaining on this surface were the object of intense alluvial gold mining activity commencing in 1857 and continuing through to the 1930's and the end of the depression. From the 1970's small scale prospecting and alluvial mining has continued sporadically to the present day within the bed of the Parapara River.

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