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Article: HBT – On Fire

Mainstream we are not! Yet another scheme that required some serious thinking outside the box. Here at HB Tunnelling, we’re proud to say that one of our strengths is our ability to think outside of the box, and deliver results that meet or exceed all the clients’ requirements. 

HBT where contacted to look if any value engineering & design change could be undertaken to remove the newly designed water tank system at Snetterton Renewable Energy Plant.!/image/image.jpg_gen/derivatives/landscape_490/image.jpg
(Artist Impression)


Snetterton Renewable Energy Plant is a biomass-fired power plant, which primarily will be fired with locally produced straw, and will have a capacity of 44.2 MW. The production will be equivalent to the energy consumption of 82,000 households and will result in a yearly CO2 reduction of 300,000 tons.

BWSC shall construct of the biomass-fired power plant, and will also be in charge of the operation and maintenance of the plant over a 15-year period.

The power plant is expected to be in operation by the spring of 2017, and is based on energy technology developed in Denmark. The main part of the power plant is a boiler from the Danish company Burmeister & Wain Energy (BWE), which is especially suited for firing with straw.

HBT’s attend site to look and have initial discussion to see if we could as a company offer anything for the client to value engineer the scheme.

Upon our meeting it became apparent that we could offer our expertise to deliver a working solution & value engineer the scheme in conjunction with BWSC lead manager John Kay.

We went away and came back with our proposal of excavating 9mtr diameter segmental shaft to a depth of 14mtrs.

The site has a very high water table, 1.5mtr below ground level with ground condition being gravels in the upper half of the construction & then into Mudstone at 8mtr depth.

With this in mind we opted to supply & install deep well dewatering tubes to allow to draw the water table down locally to allow safe excavation & the pouring of a guide collar for the segmental caisson shaft.

HBT then provided a full shaft design which had to allow for settlement & floatation along with a capacity to fulfil the plant.


Works commenced on the design which would enable the BWSC site team to see if this system being offered would be suitable. With some determination by all to battle all elements of the scheme a construction technique was finally drawn up, which would work and accepted by all.




Worked commenced on site with the supply & installation of the deep wet wells this would allow water locally to be drawn down & allow the collar to be poured safely.

Once the wells were up & running this allowed the excavation works to commence, with the guide collar being excavated & poured. Work then commence on dropping the 9mtr diameter shaft down to full depth of 14mtrs.



Overlying gravels where excavated & the caisson shaft progressed in a timely manner down into the underlying Mudstone, The Mudstone was over 350Kn/m2 in strength so worked slowed down as programmed.




Shaft down to depth, ready to install RC base slab, the RC base slab will consist over 9t of steel being installed as per the design.




BWSC lead manager John Kay said “I must say working with HBT as been a blessing, great team to be involved with; project was completed with in the programme & best of all with in the budget. The work was undertaken to very high standard & the accuracy was top draw. Nothing was to much trouble was kept up to speed daily very collaborative team well done”

For more information please contact 0845 388 3325 to speak to the HBT team

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