Penstock Replacement Contract at Portsmouth Naval Base

KBS Maritime is seeking experienced contractors for the replacement of 10 penstocks across 6 chambers at B Lock, HM Naval Base Portsmouth. This marine infrastructure project involves replacing cast iron penstock doors with new units, including associated components such as shafts, wedges, brackets, platforms, ladders, and actuation systems. The levelling penstocks are approximately 8 metres deep, while drainage penstocks reach approximately 18 metres deep. The penstock system controls seawater flow between the harbour, basin, and dry docks. Project timeline: commencement December 2026, completion February 2030. Contractors must demonstrate: (1) design, manufacture, and installation expertise in marine environments; (2) full site management capabilities under CDM regulations; (3) health and safety competency and safe practices; (4) minimum five years' experience in marine environments. All contractors and sub-contractors require BPSS security vetting and Portsmouth Naval Base security clearance. Required insurance: £10 million Public Liability, £10 million Product Liability, and £5 million Professional Indemnity. Key dates: Expressions of Interest close 18 June 2026; bidders selected by end of June 2026; Invitation to Tender published early July 2026; ITT closes early September 2026.