32-2021: Channel deepening dredging and beneficial placements: Mersea Harbour
26 October 2021
From around the 3 November 2021 the trailer suction hopper dredger Sospan Dau (IMO number: 7711062) will continue dredging in the main channel, but will move the disposal site from Horsey Island to the beneficial disposal scheme at Mersea Harbour.
The dredging contractor is the Boskalis Westminster / Van Oord Joint Venture appointed by the Harwich Haven Authority to carry out the Harwich Haven Channel Deepening Project.
The dredge area is a section of the main channel known as area C2 covering the whole width of the main channel and running from about 250m east of the Platters / Pitching Ground buoys to about 1,000m west of the same buoys. (See attached sketch HHA C2 – available in the PDF version)
Dredged material will be disposed of to four separate sites in Mersea Harbour (at Cobmarsh Island, Old Hall Marsh, Tollesbury Wick and Packing Marsh Island). The aim of the scheme is to place sand and gravel into the four areas to reinforce the eroding foreshore and provide nesting areas for sea birds.
The dredger will sail between the dredge site and Mersea Harbour generally along the routes shown on the attached sketch map MH Routes 002. The route between the dredge area and point A on the sketch is defined by the following WGS84 waypoints:
|WGS84 Latitude||WGS84 Longitude|
|51° 55.60’N||1° 21.30’E|
|51° 53.85’N||1° 21.80’E|
|51° 52.73’N||1° 21.35’E|
|51° 48.79’N||1° 21.90’E|
The dredger will dispose only at high water and be positioned as close to the disposal area as possible (see attached sketch MH 001 – available in the PDF version). Disposal will be carried out on every high water (weather permitting), day and night, either by direct pumping of material over the bow of the dredger, or via a floating pipeline. Connection of the dredger to the pipeline and positioning the placement end will be carried out by a Multicat MCS Anekke (IMO number: 9570905) and a small workboat, Taska 1. The floating pipeline will be held in place with anchors and marked with yellow can buoys fitted with flashing yellow lights.
The current programme is to commence disposal work at Tollesbury Wick and Packing Marsh Island, on or about 2 November 2021. It is hoped to finish the work at these sites and begin the placement at Cob Marsh.
On or around 16 November 2021 the operations will cease and the pipeline and the ancillary plant will be removed as the dredger has to leave the site and complete work on another project.
It is hoped that operations will begin again around 10 January 2022 (this will be confirmed by another Notice to Mariners), to complete the placement at Cobmarsh Island and at Old Hall Marsh. This second phase of the work should be completed around 4 March 2022. When completed, all plant and equipment will be removed.
It should be noted that some mooring and navigation buoys may need to be removed in order to complete these works. Further information and updates on buoy moves can be obtained from Mersea Harbour Protection Trust at email@example.com
Mariners are requested to keep clear of the equipment and the site of the placement works.
The dredging is covered by the MMO licence held by Harwich Haven Authority: L/2020/00360/2.
The disposal of material at Mersea Harbour is covered by MMO licence held by the Mersea Harbour Protection Trust: L/2018/00131/3.