Bridlington rBWD LSO


The existing Bridlington Long Sea Outfall was constructed in 1982 as a 1000 mm diameter discharge pipeline. Bridlington has combined sewers which also carry water runoff from drains / highways. Heavy or prolonged rainfall can rapidly increase the flow in the combined sewer, with essential Combined Sewer Overflows (CSO’s) allowing this excess water to discharge into a river or the sea. To facilitate the revised Bathing Water Directive (rBWD) (76/160/ EEC), it is proposed to re-route the existing CSO spills away from the inland watercourse, the Gypsey Race and the Harbour directly into the sea.

ABCO Marine Ltd were contracted by Yorkshire Water as principle contractor for Bridlington rBWD Long Sea Outfall project, we successfully tendered to Yorkshire Water and provided the following post tender design services:

  • A replacement 1.25 Km, 2000mm Diameter Long Sea Outfall with 2 port diffuser.
  • Precast Concrete Collar design for pipe ballast in line with buoyancy for marine tow.
  • Temporary Cofferdam 350lin/m on Bridlington South Beach.

Project Information

2.00m Outside Diameter HDPE Pipe and associated diffuser fittings were placed in Bridlington from Ch-0+005 on shore to the diffuser outlet point at Ch1+255 in 12 m deep water.

2.00m OD HDPE Pipe supplied free-issue by Yorkshire Water, with all pipe preparation works completed in Teeside. Marine installation of pipe precast concrete ballast collars and pipe string connection works all completed on River Tees. Marine Crane Barge utilised to form continuous pipe string 1+250lin/m long.

Design and procurement of precast concrete ballast materials for the project, providing required design factor of safety for the new outfall pipe installation but also providing the adequate buoyancy to facilitate marine tow to work location. Additional precast concrete kennels were also utilised for additional factor of safety on Bridlington Beach section.

Temporary Cofferdam installation, twin 350lin/m sheet piling 5m wide constructed on Bridlington South Beach, supported with guide beams and hydraulic winch to assist positioning and control during the pipe installation operation. Cofferdam was designed to aid excavation process of the beach trench, with long reach excavator fitted with 3D GPS dredge software.

Excavation of both land and marine trench using GPS dredge software to ensure tolerance and construction to design, all verified by periodic hydrographic survey. Hydrographic and topographical surveys of the existing seabed and beach were completed, hydrographic multibeam surveys were also utilised during the project, pre/post sink surveys of the marine trench.

Mobilisation of support marine equipment including, Jack-Up Barges, Backhoe Dredge Barge, Crane Barges, Work Tugs, Transfer Barges, spud Barges, Safety Vessels and Survey Vessels to support the marine application at two work locations in Bridlington and Teeside.

50 nautical mile marine tow of prepared pipe string, with five support marine vessels, 34 hour tow from Teeside to Bridlington. Facilitated by Port Authorities and Harbour Pilots, Fishery Liaison Personnel and Maritime and Coastguard Agency.

Pipe ‘float and sink’ installation of pipe into prepared cofferdam and marine trench, completed over two high tides, first tide used to position and secure the pipe string within cofferdam and the second tide for final pipe installation to prepared marine trench.

Commercial Diving completed by ABCO Divers Ltd, including installation of Diffuser Section and Outlet Ports, Scour Protection Concrete Mattress and Pre-cast Concrete Kennels.

All works completed including inshore tie-in connection, with the cofferdam removed from the beach and Bridlington South Beach returned.


Leslie MWH JV for Scottish Water


July 2013 – October 2014

Client Representatives

Mr Benjamin Shearer, Yorkshire Water Services


Long Sea Outfalls Overwater Piling

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