TRANSPORT AND TECHNICAL SERVICES
JERSEY ELECTRICITY’S APPLICATION TO LAY NEW LAND SIDE 90KV
CIRCUIT (THE NORMANDIE 3 INTERCONNECTOR) FROM GROUVILLE BAY TO
SOUTH HILL IN MAIN ROADS
Purpose of the Report
To obtain a Ministerial Decision giving high level approval for the Jersey Electricity Company’s (JEC) plans to lay a new land side 90KV circuit (the Normandie 3 Interconnector) from Grouville Bay to South Hill in Transport and Technical Services Department (TTS) administered main roads in terms of route, programme, traffic management and road reinstatement.
Background
Jersey Electricity started planning for a third 90KV subsea interconnector with France in 2005. This £70m project consists of three main elements:
- 19km land cable in France – to be installed by the French network operators RTE.
- 32km subsea cable between France and Jersey.
- 7km land cable in Jersey, between Grouville and South Hill.
Environmental Impact Assessments for the Jersey landing point were approved by the States in 2010 and permission granted by the Crown and the Tennants of Grouville to land the subsea cable in Grouville Bay. A basic review of the Jersey land cable route was also undertaken in consultation with TTS. Trial holes to confirm the feasibility of the route were carried out from 2011.
It was envisaged that the project would commence in the second half of 2013 with completion 2 years later in 2015. However, the permanent failure in April 2012 of the first interconnector with France ‘EDF1’ and the subsequent reduction in import capacity has made early commissioning of Normandie 3 critical to the JEC.
Planning permission from the French Government was granted in October 2012 and tender evaluations for the Jersey land and subsea cables completed shortly thereafter. On 19 February 2013 Prysmian was awarded both contracts, with Jayen Ltd being successful in securing the land side civil sub-contract. Completion of the Jersey land cable element of the project is expected in June 2014. This is a much tighter time scale than originally planned.
Consultation with those impacted en-route has been commenced and will continue throughout the duration of the project. Areas of high impact, such as Greve D’Azette and Havre des Pas will require additional consultation and advanced notices to residents, businesses and road users.
All affected Parishes have been consulted regarding the works and in particular those aspects to be carried out on by-roads. In addition the JEC have made advanced contact with key stakeholder such as the Hotels and Restaurants along Havre des Pas as the works will involve the closure of the road from late October to mid December 2013.
Land Cable Work Details
The subsea cable will be landed at a point near Fort Henry in the Royal Bay of Grouville where it will be directly jointed to the Jersey land cable, which itself will terminate at the recently commissioned South Hill Switching Station. As with previous 90KV cable projects the circuit will be fully ducted allowing six long sections of cable to be installed requiring only five joints across a 7km route.
Generally three 140mm diameter PVC ducts will be used to carry the 90KV cables (the trench being 454mm wide x 1200mm deep), although the number of ducts will be increased to six ducts (the trench being 820mm wide) from Plat Douet Junction in to Town to provide for future capacity.
Some initial duct installation has already been undertaken along the cycle track in Grouville and through some Parish lanes.
Route
The proposed route (see attached Summary Route Plan) has been derived from consideration of the following issues with the JEC:
- Route length.
- The impact of the work on the traffic network and public.
- Available joint bay locations and road service capacity.
Programme and Traffic Management
The programme for the street works element of the Project has been principally defined by:
- The commissioning date for the new interconnector.
- Seasonal constraints, particularly in relation to the closure of Havre des Pas during Autumn.
- Coordination with TTS highway works (see section below).
The major programme / traffic impact elements of the works are summarised as follows:
- Ville es Renaud / La Rue a Don as far as the Parish Hall (10 June to early August 2013): Portable Traffic Signals will be needed along this section of works with some delays expected during peak traffic times.
- La Rue a Don from Grouville Arsenal to La Rue Soulas (early July to early August 2013): A road closure will be needed.
- La Grande Route de St Clément from Golf Course / Green Road (late August to late October 2013): Westbound only traffic flow will be implemented on the Inner Road due to the close proximity of the works to Plat Douet Road junction preventing the use of Portable Traffic signals. The crossing of Plat Douet Road will be carried out in two halves (over a weekend). All works in Green Road will be done under a closure with little impact on traffic as good diversions are available.
- Mount Bingham from South Hill to Green Street (Late September to late October 2013): The road will be closed.
- Havre des Pas from Green Street to Dicq RAB (mid October to early December 2013): The road will be closed in short sections (junction to junction) to ensure access is maintained to Hotels and Restaurants and residential side roads.
- La Greve d’Azette from Green Road to Dicq RAB (mid November to mid January): Tidal traffic flow will be implemented at peak times on week days with Portable Traffic Signals at other times. Traffic delays will be most significant on Saturdays.
- Joint Bay 1/2 in La Greve d’Azette around the Demis Apartments area (Late February to end of April): Tidal traffic flow will be implemented at peak times on week days with Portable Traffic Signals at other times. Traffic delays will be most significant on Saturdays.
Otherwise works such as junction crossings, etc. will be carried out during ‘off peak’ times or out of hours such as in the evenings or on Sundays, etc. as required to minimise disruption to the network.
TTS Highway Works
The JEC’s proposed cable route will follow a number of sections of main road due to receive planned highways maintenance treatment between late August 2013 and late January 2014:-
- Ville es Renauds from Gorey Village Main Road to La Rue a Don: The scheme will involve carriageway resurfacing as well as other highway improvements as part of traffic calming measures.
- La Rue a Don from Ville es Renauds to junction of Rue des Pres Trading Estate: The scheme will involve both resurfacing and strengthening works. The overall length of the scheme is approximately 4km.
While both JEC and TTS projects have strong reasons for their programme positions, this does unfortunately mean that the time between the JEC trenching and reinstatement of these roads and their resurfacing (less than 12 months) is such that there is a real risk of trench line settlement under the treated roads unless specific safeguards are put in place. Therefore, TTS has negotiated with the JEC a number of safeguard actions in relation to the JEC’s reinstatement works and their site quality assurance (see section below).
Reinstatement Agreement (see attached Schedule)
The JEC have agreed to the following trench reinstatement related measures and costs:
A) Reinstatement Measures to be taken by JEC - main roads currently programmed for resurfacing in 2013/14
- Enhanced Reinstatement: The JEC will reinstate all carriageway excavation works as per the attached ‘Trench Reinstatement Detail – Profile B’.
- Independent Site Quality Assurance: An independent section of Parsons Brinckerhoff will be contracted by the JEC to provide regular supervision and testing of their contract’s trench backfilling operation, particularly in relation to the placing and compaction of the cement bound sand backfill materials.
Note: Importantly none of the additional reinstatement related measures outlined above in any way absolves the JEC of its normal liability for the performance of their trench reinstatements should settlement occur below TTS treated layers within a three year period of their completion.
B) Additional Treatment Measures to be taken by TTS following JEC works - main roads currently programmed for resurfacing in 2013/14
- Geotextile Reinforcement: The JEC will pay TTS to incorporate a 1.5m wide strip of Geotextile reinforcement (to be laid along the JEC trench line) during TTS road resurfacing between the new surface and binder courses layers to reduce the risk of reflective cracking along the boundaries of the JEC trench.
C) Additional Treatment Measures to be taken by TTS following JEC works - main roads not currently programmed for resurfacing
The JEC have agreed to either fund or part fund the full lane or road width resurfacing (see attached ‘JEC Main Road Reinstatement Agreement Schedule’) of the majority of roads affected by their works that are not currently programmed for resurfacing. This resurfacing work will be carried out by TTS following a suitable trench settlement period (approximately 12 months to two years) and will ensure that the highway maintenance legacy of the JEC’s trench works is kept to a minimum.
Recommendation
The Minister is recommended to approve the proposed cable route, programme, traffic management and road reinstatement measures.
Reason(s) for Decision(s)
The JEC’s proposed cable route, programme and traffic management, along with the ‘JEC Main Road Reinstatement Agreement’ (as defined in the attached schedule to the report), are acceptable in the light of the positive benefits of the infrastructure work to the Island as a whole.
Resource Implications
Normal TTS street works inspections both during works and later in relation to the monitoring of trench reinstatements. This will be followed in due course by JEC funded TTS resurfacing works as set out in the attached ‘JEC Main Road Reinstatement Agreement Schedule’.
Action Required
Street Works Manager to inform the JEC of the Minister’s decision.
Written by: | Streetworks Manager |
Approved by: | Director, Engineering and Infrastructure |
Attachments: | - Summary Route Plan - Trench Reinstatement Detail – Profile B - JEC Main Road Reinstatement Agreement Schedule |