St Helier West Substation

Opened in December 2018, the St Helier West Substation secures electricity supply to 80 per cent of St Helier homes and businesses.

Reinforcing our network

In 2006 we recognised a need to reinforce the network to the north and west of St Helier. This area had been at full capacity for some time. Several circuits between Queen’s Road and Esplanade Primary substations were installed over 50 years ago. They had become aged and stressed due to high loadings.

The St Helier West Substation project in progress.

The site also had to be accessible for maintenance but distanced enough from residential areas not to cause a nuisance.

Over the next three years, Government Planning Officials and the Parish of St Helier considered six sites with us.

Planning supported the St Helier Parish proposal of the disused quarry at West Park Gardens. Though a technically challenging site on which to build a substation, we believed it was achievable.

The five other sites considered for the substation were:

Part buried in People’s Park – welcomed by the Parish, rejected by Planning.
Former Inn on the Park car park – supported by Planning but we expected objections from residents and did not progress.
Replacing Ferguson’s Folly in Lower Park – proposed by the Parish, Planning agreed subject to design criteria.
Victoria Park – not supported by Planning.
Overdale Grounds Val Andre – technically impossible for us.

Searching for a suitable site

We began our search for a site for the new substation in 2009.

It had to be located between Esplanade Primary and Queen’s Road Primary and integrate into the existing 11kV and 90kV networks with minimal cable lengths but maximum cable separation to ensure resilience.

The front facade of the St Helier West Substation.

Nov 2013: Parish of St Helier agreed to sell us 10,000 sq ft of land on the old Westmount Quarry site.

May 2014: We were granted Planning Permission.

Sept 2014: Sale of the site goes through, and we begin a year of intensive site investigations and environmental impact assessments.

Dec 2015: We sign civil works contract with local contractor Jayen Ltd.

Jan 2016: Civils works begin. To build a substation on such a constrained and deeply sloping site, Jayen had to form a platform level with St Aubin's Road along the southern site boundary.

They had to excavate over 15m deep at the rear of the site and stabilise it. In the process, they removed 27,000 tons of material, including 5,000 tons of rock, before piling to support the building slab and erecting a new retaining wall to protect the facility.

June 2016: Contract for the build itself signed with French specialists INEO.

Sept 2017: Jayen completed the civils and handed the site to French specialists INEO who built Rue des Pres Western Primary and South Hill Switching Station. Their design uses simple air-insulated components integrated into the structure of the building.

April 2018: Two transformers manufactured by Tironi, in Modena, Italy, are delivered and installed along with other plant and equipment.

Oct 2018: States Members tour the facility while engineers continue with connections to our existing network.

Dec 2018: Following extensive commissioning, the substation is energised overnight and began delivering power to the network.

2019: We undertook extensive landscaping, restored pathways to include a viewing platform overlooking St Aubin's Bay and re-opened the surrounding area and walkways to the public.

Project diary

In January 2016, local contractor Jayen Ltd. broke ground on the challenging Westmount Quarry site. Almost three years later the substation was complete and the surrounding area was re-opened to the public.

Click more to view the detailed project diary.

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