The States Trading Supervisory Board has said it should be in a position to make a call on whether the project should go ahead by the end of the year.
But by the time the work starts the cost of delay over a decision on inert waste disposal, and paying for an interim solution of stockpiling it at Longue Hougue, could have stretched to more than £3m.
The Guernsey Development Agency, which revealed the cost of the stockpiling, wants the project to go ahead. It said there were multiple reasons for fast-tracking the creation of the island’s new inert waste disposal site on the north coast.
But it has now been decided that any reclamation, which has already been approved in principle, cannot go ahead until there was certainty on the potential adverse impact on tidal flows.
STSB has already carried out modelling of the likely impact of the reclamation project on tidal flows around the entrance to St Sampson’s Harbour.
Now it is about to go out to tender to gather location-specific data to enable a decision to be made.
Guernsey’s Waste’s senior technical adviser, Rob Roussel, said the work would validate the accuracy of the results of the previous modelling exercise.
While the entire data-gathering exercise will take a year to complete, the STSB expects to have sufficient information within the first three months to know whether or not the project can proceed, which would enable a decision to be taken this year.
The further data over the remain months of the project will be used to help to develop the optimum design for the proposed reclamation area.
GDA chairman Peter Watson said it was wrong to characterise the process as any sort of ongoing delay.
‘Since approval by the States in 2025, the GDA, in collaboration with Guernsey Waste, has been working with Haskoning to develop concept designs for the rock revetment which would contain the inert waste,’ he said.
‘This project stage is the most critical phase of construction – data-driven design. This means gathering data, designing, understanding potential impacts, feeding back to our stakeholders and adjusting accordingly.
‘Delivering a solution that doesn’t impact harbour operations, navigational safety or the environment is our top priority. As such, wave, current and seabed data is being gathered to validate the initial designs and modelling that have already been carried out.
'This isn’t a delay but instead part of standard due diligence for such a large coastal engineering project’.
It has also emerged that the stockpiling of waste at Longue Hougue will have to go on well beyond the period covered by the existing planning permission.
Eighteen months ago STSB was given planning consent to receive inert waste for stockpiling at Longue Hougue for a period of three years, with a condition that all of the material then had to be removed from the site within another three years. That application was initially refused by the DPA, but its decision was then effectively overruled by the States Assembly, acting as a quasi appeal panel.
With half of the three years consent period already gone, and no definitive decision yet on the next waste disposal site, the STSB said it would have no choice but to seek an extension to its planning permission for a minimum of two more years to allow a new disposal site, whether or not at Black Rock, is prepared to start receiving waste. A five-year hold-up could end up costing more than £3.5m.
Mr Watson said this was one reason why it wanted the project to proceed, but far from the only one.
‘The secondary benefits this site then brings to the island are even greater,’ he said.
‘The land created will offer the opportunity to build affordable homes with coastal community spaces and facilities to support all generations and the economy. By recycling this material to reclaim land, we solve a problem and create an opportunity.
‘It is critical to progress the Black Rock inert waste site for the sake of taxpayers and those that are currently falling victim to the housing crisis.’
Mr Watson said he hoped that detailed proposals for Black Rock would go to the States this year, with construction starting in late 2027.