herscha wind energy project - orkney sustainable energy chapter 5.pdforkney sustainable energy...

Herscha Wind Energy Project

Phase 2

Road Construction and Transportation

February 2013

Project Design

Richard Gauld BSc(Hons)

IEng MInstMC Dip. DesInn Dip. GeoSci

Orkney Sustainable Energy Ltd

6 North End Road

Stromness

Orkney KW16 3AG

Telephone 01856 850054

Facsimile 01856 851239

Email [email protected]

Richard Gauld is a professional design engineer, a Member of the Institute of Measurement and Control and is registered as an Incorporated

Engineer with the Engineering Council of Great Britain.

Orkney Sustainable Energy Document OSE/3551 Chapter 5 24 February 2013

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1 Summary

1.1 A locally-owned wind project is located on farmland between the communities of

Auchenblae and Glenbervie, to the south of Stonehaven in Kincardineshire. The project

extends the development by adding a further two medium sized wind turbines and an

upgraded access track.

1.2 The site and route of the access track have been subject to assessment, with ground

conditions noted and mapped. The project layout and access routes have evolved over

the assessment period, and as the project has been designed to have minimum ecological

impact, care has been taken to avoid areas of sensitive habitat.

1.3 Construction stone, concrete and all turbine components will be delivered to the

Herscha site along public roads. The turbine components will likely be delivered by sea

from the German factory to Peterhead then delivered by extended trailer along the A90

through Aberdeen then south past Portlethen and Stonehaven to Fordoun. Note that this

route was used for the first turbine delivery; no further road engineering works will be

necessary. Analysis of the transportation route identified difficulty with the right turn off

the A90 at Fordoun, and at Auchenblae, where vehicles will travel through the village.

1.4 Construction stone and concrete will come from existing Aberdeenshire quarries, and

the stone transport vehicles will access the site from the north of Newlands Farm,

largely avoiding the village of Auchenblae. A nearby sand and gravel quarry has been

identified and was used to provide roads and hardstandings for the first phase of the

development.

1.5 Assessment of the volume of materials required, the total weights and traffic numbers

has been calculated, and a method statement of the track, foundation and hardstanding

construction has been completed. Carbon balance calculations have been completed,

comparing the volume of carbon emissions from concrete production and the possible

loss of carbon from displaced soil during the road construction programme, against the

carbon dioxide emission avoidance of renewable energy production from the wind

turbines.

1.6 This report has been broken down into three parts; track and foundation construction,

analysis of the public road network for delivery and transportation of turbine

components and possible environmental risks are considered for all aspects of the

construction process, with mitigation considered where required.


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2 Track, Foundation and Hardstanding construction

2.1 The site is at Newlands Farm, on Herscha Hill, north of the community of Auchenblae,

to the south of Stonehaven. The project will consist of two further 80m high wind

turbines and an access track. The turbine location has been established following

detailed environmental assessment, and is an area which is least sensitive in ecological

and social terms. The location is well drained, mature, managed farmland, with an

existing track established for the first project.

2.2 The substation is located next to the existing turbine, north of the farm buildings and

near to the existing line of underground cables. The new turbine access track will be

levelled and made 4m wide to accommodate the large delivery vehicles, and the general

construction technique will be to remove vegetation then create a 4m wide track by

filling with as-dug stone then laying 10cm of Type 1 sub base stone, rollered flat.

2.3 The hardstanding areas will have a layered construction; geotextile will be placed on the

rocky sub-surface, with as-dug crushed rock aggregate placed on top of the geotextile,

followed by a sub-base layer. To mitigate any surface run-off problems the new track

will only be constructed in dry conditions. Construction will follow the general SUDS

guidelines published by SEPA, with a porous construction and a free-draining sub

layer[1]. The access track will have filter strips at the edges to ensure that any run-off

water is routed to the upper layers of the adjacent soil.

2.4 All soil extracted during excavation work will be used to in-fill depressions in existing

fields, and to create bunds and soak-away barriers. Turbine foundations and

hardstandings will be created, consisting of a layer of free-draining crushed stone 30m x

20m, with a nominal excavation of 10m by 10m for the foundations.

2.5 The total volume of concrete required for the foundations will be 100m3 for each site,

and the stone requirement will be approximately 900m3

for the track and hardstanding.

The requirement for the track will vary according to ground conditions; however the

maximum predicted quantities are as follows, table 1. It has further been presumed that

all of this stone shall be brought into the area, but it is likely that there will be

opportunities to recover rocky glacial till and a proportion of fractured rock during roads

and foundation excavation.


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Section Sub-base Bottoming

Access track 800m x 4m x 100mm; 320m3 -

Hardstanding 2(30m x 20m x 100mm); 120m3 2(30m x 20m x 400mm); 480m

3

Corner widening Approx 10m x 10m x 100mm; 103

Totals 450 m3,

or 900T 480 m3 or 960T

Table 1; Maximum predicted stone quantities

2.6 It is intended that as before a local quarry will be used to source the stone. The

estimated volume of stone required from Table 1 is 930m3, and although stone will be

produced during the levelling and excavation of the road and foundations, this

represents the maximum volume that could be delivered to site. Allowing for medium

size vehicles with 28T per load, this is equivalent to 66 loads for all construction work.

2.7 Concrete will be delivered to site as drybatch, to be mixed with water at the foundation

hardstanding. Each turbine location will require 100 m3 of concrete, with a limit of 8m

3

per load. The concrete mixer will carry water, with no need for local abstraction. This

volume of concrete is equivalent to 12.5 loads, although in practice it may be more

appropriate to deliver larger batches to the area. This will depend upon which civil

contractor is finally chosen for the project.

2.8 Summary construction method statement:

a. Remove any vegetation on the existing track verges, widen to 4m and fill tracks

with 100mm of sub-base stone.

b. Used crushed stone to provide hard standing, graded to match existing slopes.

c. Site office, mess, toilets and any materials storage to be sited on permanent hard

standing at the existing turbine.

d. Any soil extracted during the construction of the tracks and hard standings should

be stored on dry ground prior to distribution around the farm.

e. No bridges, culverts or other water crossings are required.

f. The turbine hardstanding is to be constructed with crushed rock from suitable

excavated foundation material, with sub-base and bottoming layers of quarried

stone as required.

g. Excavate soil and sub-surface rock till then cast foundation block on hard strata

and bedrock.

h. Roadways and hardstanding are to be unsurfaced and porous with adjacent bunds

and filter strips; active drainage is not required.

i. Reinstatement of site track; no side slopes, tracks to be flush with existing ground.

j. Topsoil fill - finished to merge with existing slopes and reseeded to match

adjacent land. Use extracted soil to fill land depressions on the farm.


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3 Access Route

3.1 The route to the site has been considered taking into account the transport requirements

of an Enercon E48 wind turbine, and analysis of the main route between Peterhead

Harbour and the site has been undertaken.

3.2 The Road Vehicles (Authorisation of Special Types)(General) Order 2003 – (STGO).

STGO permits certain types of vehicles to be used on roads notwithstanding that they do

not fully comply with the requirements that generally apply to vehicles permitted on

roads.

3.3 The Construction and Use Regulations 1986 (C&U) apply to loads which are wide or

long but not heavy. Vehicle and load lengths can be up to 27.4m long and weigh a

maximum of 44T under C&U, up to 30m under STGO and vehicles or loads in excess

of 30m require a Special Order. Widths above 2.9m and less than 4.3m are permitted

under C&U, widths between 4.3m and 5.0m are permitted under STGO and widths

between 5.0m and 6.1m require a Highways Agency Special Order [2].

3.4 The Enercon E48 turbine has a 24m long blade, while the largest tower section is less

than 30m long, and no wider than 4m. Maximum weight is 30T for the bottom tower

section, 47T for the nacelle, and the blades and hub together weigh a total of 30T.

3.5 The dimensions of the Enercon E48 turbine are within the requirements of the

Construction and Use Regulations; a Highways Agency Special Order is not necessary.

The turbine components are Abnormal Indivisible Loads as defined under STGO, and

accordingly a BE16 permit from the Scottish Executive will be required.

3.6 The turbine components will be delivered by sea from the Enercon factory in Germany

then transported by extended trailer along the A90 from Peterhead Harbour, on to the

A90 before travelling through Aberdeen then south past Stonehaven to the Auchenblae

area. The manufacturer is experienced in transportation of their wind turbines, and do

not foresee any difficulties in the transportation of the turbine components from

Peterhead to Auchenblae; the route was used to deliver the first turbine.


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3.7 Analysis of the transportation route has identified the following potentially difficult

locations:

a. The right turn at the Fordoun junction off the A90. Although this is a dual

carriageway, traffic travelling northwards should be halted by police before the

long vehicles traverse the carriageway;

b. Auchenblae, where all delivery vehicles will have to travel through the village.

It would be prudent to have the road cleared of any parked vehicles on

narrower stretches and bends to reduce collision risk;

c. The farm entrance after Burnmouth Bridge to the north of Auchenblae, where

road widening has already been completed at Newlands farm to allow access

for long transport vehicles to make a left turn to the farm.

3.8 The corners of the road junction off the minor road north of Auchenblae shall require

temporary modification to allow access to the longer loads. This will entail laying down

sub-base stone over an area around 5m back from corner of the junctions at a radius of

30m, and the temporary removal of any fencings. This stone could be removed after

construction, however it may be prudent to leave in place in the event of future blade

replacement or refurbishment.

3.9 The access route for all components follows the main A90 from Peterhead Harbour

south through Aberdeen to Tullos, before re-joining the A90 southwards on the outskirts

of Aberdeen. The vehicles will then travel southwards along the A90, bypassing

Stonehaven then turning westwards at the Fordoun junction. The vehicles will skirt

around Fordoun, travelling over the main railway bridge to the north of the village,

before travelling westwards to Auchenblae, then through the village and onwards to

Burnmouth Bridge then Newlands Farm.

3.10 The site access follows the route through the farm to the existing turbine, with a new

track then travelling eastwards along the northern boundary of Newlands Farm,

connecting to the sites of the new turbines.


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4 Delivery of components

4.1 A transport route has been determined by travelling the route from Aberdeen Harbour to

the turbine site. With the exception of the above locations, there should be no difficulty

in transporting components of an Enercon wind turbine along the public roads.

4.2 There will be five large loads per turbine, consisting of a bottom tower section,

approximately 30m by 4m diameter, a narrower upper tower section 19m long, a nacelle

which weighs 47T, a set of blades 25m long, 4m high and 2m wide and a load

consisting of the hub and internal fittings. In addition a crane will be required for the

final assembly, which is delivered as a permitted load under C&U regulations.

4.3 In addition there will be transformers delivered to site, along with high voltage

switchgear and cabling. The detailed turbine construction programme will be issued at

the time of construction, but can be summarised as follows. Cranes will be needed to

offload from the transporters and to lift and assemble the components, and a large 350T

telescopic crane will be required for assembly:

1 Deliver and install the transformers onto the foundations.

2 Erect the lower tower sections directly off the trailer onto the foundation;

3 Deliver the upper tower sections and nacelles to the site;

4 Erect the upper tower section and nacelle;

5 Deliver sets of blades to the site and assemble on a hub into a rotor;

6 Install the rotor assemblies.

4.4 The delivery of long loads through Auchenblae has the greatest potential for disruption,

with traffic management required. The first turbine was delivered at Midday, when the

village is at its quietest; there was little in the way of disruption. Although there are

alternative routes for other vehicles, the most appropriate time to deliver these

components through Auchenblae was found to be during the daytime and midweek,

when the roads are at their quietest. Before any wind turbine components are

transported to site, the project owners and designers will consult with Aberdeenshire

Council Roads Department and the Police to ensure acceptability of the route to site.

Existing public road culverts, bridges, verges and street furniture will be surveyed by the

project developers in conjunction with the Roads Department. A schedule of loads and

a timetable will be prepared and circulated prior to delivery.


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5 Environmental impact and mitigation

5.1 A carbon balance calculation has been completed, based on recommendations from the

Carbon Trust. It should be noted that carbon loss was considered when examining the

soils, and CO2 emissions were considered when examining concrete manufacture.

5.2 The maximum volume of topsoil that could be disturbed is approximately 180m3,

consisting of an 800m long track widening by 1.5m and a hardstanding 20m x 30m, a

total area of 1,800m2 of construction work at an average depth of 0.1m. The carbon

content of soils has been discussed by Chapman et al[3] and for the Herscha assessment a

figure of 0.069 tonnes of carbon per cubic metre of soil has been used; the carbon

content of the soil is estimated to be 12T.

5.3 The carbon emission factor of grid electricity is 0.117 T/MWh [4] and assuming a mean

windspeed of 7.8m/s, two Enercon E48 wind turbines will produce an annual energy

yield of approximately 3600 MWh at a capacity factor of 31%. An average production

of 10 MWh per day gives a positive carbon balance of 1.2 T per day, assuming a

mixture of conventional generation is displaced; 11 days of generation are required to

compensate for the potential carbon released from the soil. It should be noted that the

construction process will endeavour to retain the integrity of the soil systems to avoid

release of carbon, and all soil will be reused in other parts of the farm.

5.4 It is recognised that concrete production results in the emission of CO2 from both the

energy required and from the calcining of limestone when producing cement. A cubic

metre of concrete is made from 2T of aggregate and 450kg of cement and the project

will require approximately 200m3 of concrete. 200 m

3 of concrete requires 90T of

cement, and assuming 0.75T of CO2 per tonne for the energy requirement, and 0.5T of

CO2 per tonne from the calcining of limestone[5], the total CO2 emissions during

concrete manufacture for the project is 110 T. Using a CO2 avoidance factor of 0.43T

CO2/MWh, the wind turbines provides a positive CO2 balance of 4T per day; 26 days of

generation are required to compensate for the carbon dioxide released during concrete

manufacture.

5.5 The construction activities during mobilisation and installation of the turbines represent

a pollution risk. This may be through operational discharges or as the result of an

unplanned or accidental event. Measures will be taken to protect against the release of

any material with the potential to leach into the soil or water courses.


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5.6 The construction of the access track and the area of hardstanding have a potential

pollution risk, and SEPA’s Pollution Prevention Guidelines PPG1, PPG5, PPG6, PPG8

and PPG21 have been adopted by the project[6]: To combat the potential risk of run-off

from these areas, it is proposed that some of the mechanisms used to construct

Sustainable Urban Drainage systems be adopted, using of a permeable surface on the

access track to allow water to pass through the upper layer, along with filter strips and

bunds of vegetated soil to providing filtering and flow attenuation of water run-off.

5.7 The construction of the wind turbine foundations involves pouring fresh concrete, and

has the greatest risk of pollution impact. The nearest watercourse is around 900m from a

turbine location, reducing the risk of pollution run-off and it is proposed that all

concrete be brought onto site in a dry batch form to minimise the risk of spills.

Cleaning of shutters and the washing of equipment will only be done away from site.

To minimise risk of pollution from oils and fuels during project construction, all work

will be to COSHH regulations[7] and any machinery, equipment or construction material

will be located on areas of hardstanding away from water courses. Any waste will be

transported away from the work area and disposed of using standard waste handling

procedures.

5.8 Silt run-off both direct and indirect to watercourses can cause problems to burns and

rivers. Silt can access watercourses both by uncontrolled overland flow and directly by

percolation into field drains and rock fractures. It is proposed that the access track and

the hardstanding area will be graded and a grass swale or filter drain be installed at one

side to collect surface run-off. The surface run off from the filter drain will discharge to

permeable areas adjacent to the access from the public road, and will be controlled by

using a series of filter strips and soil bunds next to the access track.

5.9 Fuel or oil pollution from the construction vehicles would have a serious impact on

water quality should it enter any water courses, and accordingly fuels will be managed at

the farmyard, well away from any water courses, and good site management will be

established. Refuelling activities for construction vehicles and equipment will be

restricted to contained areas of hardstanding at the fuel storage area, and to minimise

the potential for contamination of land, any spills would be contained during fuel

transfer, and a store of absorbent material will be provided on site.


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References, web links and bibliography

1 SEPA recommendations on drainage systems in Scotland - Sustainable Urban Drainage

Systems (SUDS). http://www.sepa.org.uk/publications/leaflets/suds/?lang=_e

2 The Road Vehicles (Authorisation of Special Types)(General) Order 2003.

http://www.dft.gov.uk/stellent/groups/dft_rdsafety/documents/page/dft_rdsafety_023695-

01.hcsp

3 Chapman, S.J., Towers, W., Williams, B.L., Coull, M.C., Paterson, E. (2001) Review of the

Contribution to Climate Change of Organic Soils Under Different Land Uses. Scottish

Executive Central Research Unit.

4 The Carbon Trust. Guidelines on measuring carbon and CO2 emissions from electricity.

http://www.thecarbontrust.co.uk/carbontrust/low_carbon_tech/dlct2_1_6.html

5 Boden, T.A., G. Marland, R.J. Andres, (1995). Estimates of global, regional, and national

annual CO2 emissions from fossil-fuel burning, hydraulic cement production, and gas flaring:

1950-1992, Oak Ridge National Laboratory. Report ORNL/CDIAC-90, NDP-030/R6.

6 SEPA pollution prevention guidelines http://www.sepa.org.uk/guidance/ppg/

7 Control of Substances Hazardous to Health COSHH Regulations http://www.hse.gov.uk/coshh/


11

Appendix 1

Transport Route Maps and Photographs


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Stage 1:

Fordoun Junction

Transport route is the A90 from Peterhead

until the Fordoun turn off is reached, south

of Stonehaven. Turn right off the A90 then

veer around Fordoun, taking the minor road

over the railway bridge.

Traffic management may be required to

allow long vehicles turn off the A90.

Stage 2:

South Auchenblae

Travel northwards from Fordoun to

Auchenblae along the minor road. Continue

into the village, taking the route through the

High Street.

These roads are single carriageway and

traffic management will be required in the

village centre. Care is required to avoid

collision with buildings, walls and road

verges.

Herscha Wind Energy Project: Transportation Route Details.

30m radius

30m radius

Stage 3:

North Auchenblae

Travel along the High Street, on to

Inverurie Street then out of the village on

Glenfarquhar Road.

These roads are single carriageway and

traffic management will be required in the

village centre.

Stage 5:

Newlands

Follow improved access track to the west

of Newlands, travelling directly to the

turbine site.

Stage 4:

Burnmouth Bridge

Continue northwards out of Auchenblae,

cross Burnmouth Bridge then travel north-

eastwards towards Newlands Farm.

Junction widening has been completed at

the Newlands Farm site access.

Herscha Wind Energy Project: Transportation Route Details.

Herscha Wind Energy Project: Transportation Route Photographs

Stage 1A:

Fordoun Junction

Stage 1B:

Former Fordoun Lorry Park

Stage 1C:

Fordoun Railway Bridge

Herscha Wind Energy Project: Transportation Route Photographs

Stage 2:

South end of Auchenblae

Stage 4:

Burnmouth Bridge and

junction, with the project site in

the distance.

herscha wind energy project - orkney sustainable energy chapter 5.pdforkney sustainable energy...

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