THE MAGAZINE FOR THE DRAINAGE, WATER & WASTEWATER INDUSTRIES
SPECIAL WORKS
The tank was therefore redesigned, reducing its height by approximately one metre to allow a greater depth of fill on top. However, to maintain the same volume, the tank’s footprint had to be extended outwards to make up for the reduced depth.
The redesigned tank now covered an area of approximately 25m x 17m but due to the space restrictions of the site layout, it has to be a complex and irregular shape in order to occupy the space available.
To support the sides of the excavation, East Rudland Construction called in Groundforce Shorco.
“I’ve worked with Groundforce for over 20 years and I know them well. I knew they would have the right solution,” says Steve.
East Rudland Construction gave Groundforce Shorco the dimensions of the tank and Groundforce Shorco designed the temporary works solution, employing its modular Mega Brace system to support a steel sheet-piled retaining wall and braced with MP50 and MP150 hydraulic props.
The Mega Brace system is designed so
that beams of virtually any length can be assembled using the modular sections in different combinations. However, this excavation’s complex shape meant that certain lengths of the perimeter frame were little more than one metre in length – too short even for Groundforce Shorco’s standard equipment.
Groundforce Shorco therefore provided bespoke lengths, modified to suit the application. To support the sides of the 3m-deep excavation, they supplied 170 lightweight GFI interlocking steel piles, each 6m in length.
Larssen piles would normally have been the default option, but site constraints ruled this out, explains Steve.
“Larssen piles are strong, heavy-duty sheet piles with a deep U-shaped cross section and we would have struggled to remove them after completion of the excavation without resorting to a larger excavator.
“We couldn’t use a heavy excavator without risking damage to the installed tank. There was also very limited space in which to manoeuvre a large machine. Therefore, we had to find an alternative.
“We used about 170 6m-long GFIs to stop
water flow into the excavation. These are interlocking sheets offering a lighter option than the Larssen piles. They are much easier to remove from the ground.”
To permit the lightweight GFI piles to be driven to the correct depth, East Rudland Construction pre-augured the perimeter of the excavation, loosening the soil and allowing insertion of the sheet piles.
Another requirement was to carry out extensive frame-to-sheet-pile welding to prevent lateral movement of the frame. The irregular shape of the excavation meant there were numerous short lengths of frame subject to relatively high end-loads. Welding the frame to the sheet piles helped ensure rigidity.
“We did all the installation ourselves, using our own plant and equipment, but we relied heavily on the design and technical support provided by Groundforce Shorco,” says Steve.
“I kept in regular contact with their area manager Trevor Kendrick – whom I have known for years – and he was absolutely fantastic,” Steve continues. “The job started out as a potential headache but together we found a solution and made it work smoothly.”
linkedin.com/company/draintrader
January 2025 |
19
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76
