Measuring quantities pumped ashore
There are several factors to take into account when estimating the quantity of sand reaching the beach. The amount we claim as pumped ashore is recorded by the dredger and we have to allow for a “bulking factor” of 1.2 due to the material being mixed with water in the hopper. For instance, if we’re told that 3,000 cu.m. has been pumped from the hopper it would equate to 2,500 cu.m. actual material dredged.
We then allow for an estimated 20% of that 2,500 cu.m. being lost to the foreshore during pumping, so only 2,000 cu.m. might be left on the beach.
These figures provide guidelines. Beaches are independently surveyed on a daily basis, comparing levels and widths to a baseline survey carried out before work commenced, and in that way we get a far more accurate idea of how much sand has actually been delivered.
TSHD “Oranje” was built in Holland in 2004 for Royal Boskalis Westminster:
- At 156m long Oranje is 60m longer than any of the dredgers that worked on the replenishment project last winter – and as long as the Barfleur
- Her hopper capacity is almost 16,000 m³ – about 4x that of last year’s vessels
- She’s quicker too, with a top speed of 16.2 knots.
The number of loads brought to shore each day was much reduced on Phase 1 due to the distance Oranje had to travel between dredging off the SE coast of the Isle of Wight and pumping ashore at Bournemouth. Last winter’s project averaged 5 loads per day; for this project just one or two loads were delivered in a 24 hour period with an approximate ‘turnaround time’ of 10 hours.
|Total volume measured on the beach||-||897,722|
**Of the total 1.02 million m³ of sand recorded in the dredger’s hopper, 898,000 m³ was actually delivered to the beaches (find out more).
|14th||The ship carrying lengths of pipeline has arrived in Poole Harbour and is being off-loaded. Meanwhile the crane awaits deliveries at Branksome Chine car park (parking restrictions in place).|
|15th||First deliveries, sections of pipe for the sinkerline are offloaded from midday.|
|16th||Sand levelling plant has arrived and work has started on welding sections of sinkerline.|
|17th||The appalling weather this morning put a temporary halt to operations, it is too windy for the crane to operate safely. Things improved this afternoon and we anticipate we will finish off-loading tomorrow morning.|
|20th||The crane has left site and parking restrictions have been lifted. Work on the sinkerline continues along the beach at Poole.|
|24th||Work on the sinkerline has progressed to 'No Mans Land' just east of Canford Cliffs Chine. The crew expect to have completed it by 1st December.|
|29th||1,050m of sinkerline now complete, 100m to go. Completion still on course for Friday, 1st December, with the dredger due to arrive on the 11th.|
|4th||The weekend's gales caused a considerable amount of overtopping and damage between Bournemouth and Boscombe Piers, where the beach is low and awaiting replenishment. Large quantities of sand, gravel, seaweed and debris were thrown onto the promenade. By contrast, the newly replenished beaches at Southbourne (Phase 1) stood up to the storm very well, with a further slight increase in crest level, and no water or debris reaching the promenade.|
|5th||The project management team visited Harwich, to brief the dredger Captain about the Bournemouth project. TSHD Oranje is now expected to arrive at about midday on Wednesday 13th December, when her work at Harwich is complete. At Poole, the sinkerline is due to be completed over the next couple of days, and will be moved offshore on Saturday the 9th (weather permitting) to its position between Bournemouth & Boscombe Piers.|
|9th||The 1,150m long sinkerline is at Bournemouth, brought ashore at the bottom of the East Cliff lift. It has been sunk to the seabed and awaits the arrival of the TSHD Oranje.|
|12th||The Oranje is expected to arrive at Bournemouth tomorrow between 14:00 and 16:00. A section of onshore pipeline has been added to the sinkerline today, preparing for her arrival.|
|13th||The Oranje arrived at 17:30 this evening with a full hopper; the first load of sand was pumped on to the beach from 18:00.|
|14th||Valves and a 'T' piece have been fitted to the end of the sinkerline to allow sand to be pumped both east and westwards from its position at East Cliff. The second load of sand was pumped (east) between 06:00 and 09:00 this morning and #3 at 18:48; an early morning & early evening visit by Oranje is likely to be the routine for the next few days at least.|
|15th||Load #4 delivered at 07:15. Some 150m (approx) of beach has now been replenished between groyne Nos. 14 & 15. Each hopper load delivers 11,500-13,000 m3 of sand and takes 2-3 hours to offload.|
|19th||Load #13 was pumped on to the beach between 07:30 and 09:30 today between groyne Nos. 17 & 18. It is taking 2-3 loads to fill a groyne bay, and each bay represents approximately 150m of beach.|
|20th||Load #16 at 05:40 completed work to groyne No. 18. The dredger is due back at about 16:00 hours.|
|23rd||Load #22 arrived at the beach at 11:00 today between groyne Nos. 20 & 21. Approximately 1,050m of beach has now been completed and the aim is to reach Boscombe Pier by Christmas Day.|
|27th||Load #30 was delivered to the beach east of Boscombe Pier this morning. Some 1,700m of beach has now been replenished using approx. 315,000m3 of material. The aim is to reach the easternmost point of BIS4.2 (Portman Ravine Zigzag) by 4th January; the operation will then return to the sinkerline between the two Piers and start pumping westwards towards the Borough boundary with Poole.|
|29th||Load #32 took us up to groyne No 24 today - one groyne beyond Boscombe Pier - after which Oranje went to refuel at Southampton. She is due back tomorrow morning.|
|2nd||The Oranje spent Sunday night in Poole Harbour so that the crew could enjoy the New Year celebrations at Poole Quay; they were back to work the following day. Load #38 delivered this morning completes more than 2km of beach using 475,000m3 of sand. Recent bad weather has delayed the project but only slightly and the revised target is to reach Portman Ravine Zigzag on 5th January.|
|5th||2,600m of beach has now been replenished with about 600,000m3 of material, and work towards Southbourne should be completed tomorrow. If all goes to plan, replenishment will continue with sand being pumped west of the sinkerline between the piers on Monday, 8th January.|
|6th||Load #47 pumped ashore at noon today between groyne Nos. 28-29. Just three more loads needed to complete work on this section of beach.|
|9th||The last load for the eastern end of the project was completed at midnight last night bringing the total quantity of sand delivered to the coast to date to 625,000m3. The onshore pipeline is now being dismantled. Meantime, load #52 was pumped from the sinkerline position to the west (toward Bournemouth Pier) between groyne Nos. 12 & 13. It is anticipated that work will reach Bournemouth Pier by Tuesday afternoon, the 9th. As pipework goes on beneath the pier Oranje will leave for minor repairs and should return to continue pumping on Thursday.|
|11th||Pipework beneath Bournemouth Pier is complete but there are some engine problems for Oranje; repairs take place at a sheltered location. Delays due to the poor weather lead the project team to revise the anticipated date of completion to 24th January.|
|14th||Crowds gathered on a mild & sunny Sunday to watch work as it progresses towards Durley Chine.|
|16th||Members of the Institution of Civil Engineers (ICE) visited the project today; presentations and lunch at the Royal Bath Hotel were followed by a site visit to Durley Chine. A planned trip out to sea for a close-up view of Oranje approaching and linking to the sinkerline had to be cancelled due to poor weather. Loads #67 & 68 pumped ashore. It is estimated that there are just 14 more loads required to complete the project (7-8 days work).|
|17th||After delivering load #69 at Durley Chine this afternoon Oranje left for bunkering in the Solent. She is due to return with the next load late tonight or early tomorrow morning - weather dependent. Storm force winds forecast overnight.|
|19th||Work resumed yesterday evening when the storm had passed. Load #72 was pumped ashore early this morning, completing the beach at Durley Chine. Some 1,788m of shoreline now replenished to the west of the sinkerline. Total sand pumped ashore 765,00m3.|
|21st||Load #77 was pumped ashore this afternoon, watched from the promenade by a large crowd enjoying the January sunshine. 2km of beach has now been replenished to the west of the sinkerline, reaching Middle Chine, with works nearing completion. Weather permitting, the last load should be delivered to the shore on Tuesday.|
|22nd||Project Managers confirm the final load is scheduled to be pumped ashore tomorrow (Tuesday) at about 10.00 a.m.|
|23rd||Load #81, the last of the project, was pumped ashore today at Alum Chine. TSHD Oranje has departed for Rotterdam; work now starts to dismantle the pipeline along the beach.|