pre planning submission op05 derryduff ... - Organic Power

2.2.3 Positive Impacts
The following environmental benefits of the area will be positively affected by the development:
• Direct local income from sustainable use of the environment will increase significantly, enhancing the economic
integrity and security of the area, including a minimum 1 high quality sustainable job in monitoring, and indirect job
creation through management. Total permanent job creation will be equivalent of 2 full time jobs.
• The facility will require the construction of access roads, a turbine hall, penstock, upper and lower
reservoirs resulting in significant local economic activity during the construction period.
• The project will yield investment return for local and company investors. The facility will be financed
through a prudent combination of debt and equity.
• Strategic energy infrastructure which will be emissions free and imported fuel independent, consistent
with EU, State, and County policy will be commissioned, enhancing the future energy security of the
community.
• The catchment of the Derryduff stream will be increased by placing catching drains along the edge of
the access road to the upper reservoir. This will enhance the productivity of the watershed to the extent
that micro-hydro scheme proposed on the stream by the Unicorn Foundation becomes more viable. The
available penstock head for this micro-hydro scheme will also be increased as a result of the re-routing of
the stream bed around the lower reservoir. (Note: this stream has no fish life, due to its current ephemeral
nature which is caused by low catchment area)
2.2.4 Negative Impacts
The following environmental benefits of the area may be potentially negatively affected by the development:
• The local visual impact is expected to be minimal. Some visibility of the lower reservoir may be
observable from the vicinity of Lough Atooreen on the mountain road from Dromduff to Maugha road in
Tooreen townland. Otherwise visual impacts will be restricted to the outer bank of the upper reservoir
and the exposed sections of the penstock.
• The current use of the proposed site (approximately 30 acres) for grazing sheep will be lost of the site is developed.
• The existing blanket peat in the areas of the two reservoirs will be removed.
• The water supply to the Derryduff farm community and Unicorn Foundation is sourced on the mountain
from surface runoff. During construction of the upper reservoir and its access road, potential contamination of
this water supply could arise from soil and rock disturbance. This will be mitigated by the installation of a
sand & gravel filtering beds on the water supply, to be installed prior to the commencement of works at
higher elevation than the water supply intake.
As is evident from the above list of impacts arising, the benefits that would be foregone in a do-nothing scenario
are significantly greater than the loss of benefits which would result from the development. An attempt to
quantify the economic costs and benefits on an annual basis is given below.
Annual National Economic Cost-Benefit Proposed PUMPED HYDRO ELECTRIC STORAGE SCHEME.
Item Cost Benefit
National Fuel import costs avoided (60,000 barrels year @€75/barrel, based on gas power) 0
4,500,000
National Carbon Payments avoided €20 x 36,000 tonnes 0 720,000
Lost sheep grazing (1 sheep/2ha, 12.5ha lost, sheep @70) 400
National Economic Totals 400 5,220,000
• The net national economic benefits over 50 years will be in the order of €260,000,000.
• A Do-nothing scenario would result in the avoidance of potential savings on the national obligation to
purchase fuel and carbon emissions rights worth over €0.26 billion, over fifty years.
• The proposed development does not have nor will have any detrimental permanent environmental
impacts on the area or surroundings, if properly designed, and operated.
• There are no environmental benefits from a do-nothing scenario.
• In conclusion, a do-nothing scenario should not apply in this case. This is the century where the whole
world is starting to take corrective action against anthropogenic climate change, and to start developing
towards a sustainable future. In this new world paradigm, the generation of electricity, a commodity that
everybody enjoys and nobody wants to give up, will largely come from low carbon renewable energy.
The proposed project will provide a portion of that future energy requirement.
2.3 Construction
2.3.1 Public Road Access / Coomhola Bridge/ Ford
There are two access alternatives to cross over the Coomhola River from the main Coomhola- Borlin road, which
are currently under evaluation:
• Via Derryduff bridge - widen existing bridge, and widen road to Derryduff farm from bridge
• Improve private existing ford access to Derryduff farm from Rangaroe, upstream (~1km) of bridge
2.3.2 Site Compound, Temporary Site Offices
At the initial stages of construction, the proposed area for the site offices and compound will be stripped of
topsoil and this will be banked around the area. Teram geotextile will be placed on the subsoil to stop the
particles boiling up through the two layers of compacted clause 804. Included in the compound will be parking
for fifteen cars/vans, bunded diesel storage to 110% of the largest tank and a concrete area with gull to a grease
trap and silt trap to catch spills and sediment. A perimeter hoarding 2.4m high, will be constructed and painted
green to match the existing surroundings of trees and green area.
Temporary site structures will consist of ten port-cabins and six small lockable steel shipping containers for small
plant and hand held tool storage, and personel protective equipment (PPE) storage. One of the port-cabins will
be for the subcontractors that are expected during the construction period, and the other will be a larger one for
canteen and meeting room. A toilet unit will also be provided and regularly maintained and content disposed of
by a registered waste management company. The waste management will also provide a number of skips/ large
bins for recyclables and non recyclable materials that will be generated on site and within the compound.
2.3.3 Access Roads
The following sequence of on site road construction will be required
• Improve road from ford to Derryduff forestry road entrance (if using ford for access)
• Improve existing forestry road
• Build new road to access powerhouse/lower lake
• Build new road to reach top lake
• Roads on dam crest
• Ramps onto crest and ramp down to reservoir bed
Access roads into and within the site will range from 4.5m to 6m width and will be laid using 500mm of 50mm
aggregate down. Some sections of this road will be finished with tarmacadam. Stone will be obtained from
quarrying stone during lake excavation, and no imported stone will be required.
2.3.4 Structures.
The proposed project is a large civil engineering project, involving heavy structures to contain the forces of
standing and contained flowing water, in addition to the pump turbine. All structures will be designed by one of
the leading structural engineering practices in the country, Niall Fitzsimons and Company, Consulting Civil and
Structural Engineers. The structures required are described below. Detailed foundation design will be carried out
by, post obtaining planning permission.
Peat Storage
Two peat storage structures will be placed on site. The structural integrity of these stockpiles will be provided
by bunding structures and the gravtitational integrity of the peat which will improve with time as the moisture
content reduces. The stockpiles will be sealed by smoothing to allow precipitation to be shed from their surface.
Gravity Dams For Reservoirs
Dams will be constructed using excavated stone placed on appropriately designed rock benches. As the name
infers, the force of gravity is used to provide structural integrity.
Reservoirs
The reservoirs will be constructed on the existing bedrock, and foundations will be blasted partly into the rock.
A porous drainage layer will lie on top of the bedrock to allow for the cotrol of groundwater seepage. This is
overlaid by an impermeable flexible composite of bituminised concrete and bitumen. The leakage tolerance of
the reservoirs will be 5 l/s each from an economic point of view. Nevertheless, the performance of modern state
of the art sealings are better than 1 l/s.
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