Incredible Hulk To The Rescue!

Hulk Prepares for Action

One of the most powerful drilling rigs in the UK – affectionately known as Hulk – was the unlikely hero called in when HBPW was asked to carry out quayside ground investigations in Porth Penryn Harbour near the Welsh city of Bangor.

Construction work at Dinorwig Hydro Power Station and Pentir Sub Station, includes provision for huge 250 tonnes transformers which have to be landed at the 200 year old facility, run by Dickie’s Boat Yard.

But all parties needed to know that the quayside was up to the job, fearing dangerous collapse of the ground or ancient walls if the combined weight of either a huge lifting crane – or Heavy Goods Vehicle – along with one of the massive transformers, put too much strain on the waterside structure.

Geoenvironmental Engineer Jay Fox from HBPW, explains.

“We had to consider two possibilities. The massive roll on roll off delivery vessels are able to carry a pre-loaded specialist Heavy Goods Vehicle, in this case with the transformers. It was a question of whether they could simply drive off the ship and go about their business, or whether we needed to make provision for a temporary lifting crane to remove each of the 250 tonnes transformers off the ship for onward transportation by waiting vehicles.”

Either option needed proof that the quayside was up to the additional weight.

“The quayside is around 200 years old,” added Jay “and was originally developed for the international transportation of locally mined slate. Whilst the make-up of the harbour is not well understood, we do know that most of it was constructed with slate wastes.”

And therein lay the problem.

“Groundworks were required to ascertain the integrity of the quayside’s construction, so we brought in ‘Hulk’, one of only four series 900 drilling rigs in the UK. Weighing in at 27 tonnes the ‘900’s’ are more used to drilling deep boreholes up to several hundred metres deep, meaning our 18m requirement was a walk in the park, taking just a few hours to complete instead of, potentially, several days with a lesser rig.”

The Series 900 Drilling Rig

Local ground conditions were unknown but, thanks to the power of Hulk, and its ability to install the casing simultaneously with drilling, it proved ideal for the unstable ground at Porth Penryn.

“These rigs are normally used for installing deep water wells and geothermal ground source heat pump loops so the harbour job was barely even a challenge. The 900’s are not suitable for all sites as they need to be delivered and collected on low loaders.

“Their sheer size and weight can also be a problem on softer sites but, in this instance, it enabled us to get the job right, completed on time, on budget and right first time.”

Moving forward investigations have shown that use of the quayside is suitable for transformer delivery and other potential future assignments for the Porth.