Developer Vineyard Wind will need four to six weeks to assess the impact for the first commercial-scale US offshore wind project after a federal agency’s recent unexpected decision to delay issuance of a final environmental study necessary for construction start this year, according to monopile supplier Sif.

Vineyard – owned 50% each by Iberdrola’s Avangrid and Copenhagen Infrastructure Partners – on 8 July awarded Netherlands-based Sif a landmark contract for 84 monopiles with production at a facility there scheduled for first half 2020.