2021:425 - Dublin Port ABR Project, Capital Dredging, Season 4; Innermost Channel Area (within Bull Walls) and across Inner Channel slopes, Dublin, Dublin

Capital Dredge Season 4 commenced on 3 October 2019, operating over a six (6) month period, and was competed on by 31 March 2021. The season was sub-divided into six (6) mini-dredge campaigns. A total of one thousand, one-hundred and twenty-six (1126) dredge-runs were carried out as part of this final dredge season: one hundred and ninety-five (195) dredge runs being completed for Campaign 1; two-hundred and nine (209) dredge-runs for Campaign 2; two-hundred and twenty-nine (229) dredge-runs for Campaign 3; two-hundred and thirty-nine (239) dredge-runs for Campaign 4; one hundred and sixty-eight (169) for Campaign 5; and eighty-five (85) for Campaign 6.

For the most part, dredging focused along the innermost channel area, located within the port’s breakwater structures (North/South Bull Walls). Mini-dredge Campaigns 1-5 dredged exclusively within the Bull Walls, while Mini-dredge Campaign 6 concentrated its operations along the channel slopes outside the Bull Walls, predominantly removing redeposited (storm related) sediment.

Forty-nine (49) objects were recovered from the archaeological monitoring process. Thirty-two (32) of these constitute ship-related timbers, comprising the following: fourteen (14) planking timbers, thirteen (13) framing timbers, three (3) timber fragments, one (1) timber dowel, one (1) deck timber, and one (1) miscellaneous timber. Additional finds included: six (6) lengths of hemp rope, three (3) iron fastenings, two (2) wrought-iron chains, one (1) piece of wrought-iron plate, one (1) anchor component (crown), one (1) piece of shoe leather, one (1) plough-claw, and one (1) fragment of granite masonry.

A series of pre/post-dredge archaeological dives were completed as part of Capital Dredge Season 4, carried out in October 2020 and May 2021. This included Items 1-5 below:
1. Inspection of marine geophysical targets identified as part of pre-dredge multibeam survey of the upriver area of the Navigation Channel, to the west of Buoy Number 14.
2. Underwater assessment (yearly inspection) of the Millstone Wreck to assess the condition of the wreck site, seabed topography, and depth of overburden covering the site.
3. Extended survey of the seabed surrounding Location C.
4. Underwater inspection at Location D, an area of seabed positioned at the top of the channel slope, on the north side of the outer fairway, at a point 300m west of Buoy Number 1.
5. Removal of a series of disarticulated ships timbers that are lying on the seabed adjacent to the rock-armour for Poolbeg Lighthouse (Site 2/Poolbeg 4).

The archaeological diving for Items 1-4 were carried out under licence numbers 17D0077 and 17R0196 (2020-2021 ext.), while underwater work at Site 2/Poolbeg 4 (Item 5) was carried out under licence numbers 21E0187, 21R0059, and 21D0044.