This has been a World First for a number of different reasons. The goal – to stabilise a slope carrying a major 8 lane highway.
At one point, a shift occurred which moved a section of the road 3ft (1m) to the side. This caused all sorts of problems, most notable that this is a major port of entry into one of the most important States in the country.
A large dewatering shaft with a 23ft (7m) diameter was excavated to a depth of about 400ft (120m). Down the length of the shaft, horizontal dewatering wells are being drilled into the slope to assist with dewatering. A crew and their equipment are lowered into this pit below the static water level so dewatering has to take place 24 x 7.
These horizontal dewatering wells will carry the water from the unstable ground into the vertical shaft. Water from all the horizontal dewatering wells will run into this pit from where it will be pumped into holding tanks for settling and then into a pond.
Pictures tell a thousand words so lets get to it.
Boreline connected to sludge pump
A 600GPM sludge pump has been fitted inside a protective cage and the Boreline hose and couplings attached. The power cable has been attached with the red Cable Straps indicating of the proximity of the pump.
Pump lifted into shaft
The pump is lifted and will be lowered into the large dewatering shaft.
Boreline and power cable ready for installation
Note how the power cable has been attached to the Boreline along the entire length with enough power cable to accommodate the expected 3% elongation of the Boreline when in operation.
Ready to install
The top end of the Boreline has been attached to a loader to assist with installation. Unlike rigid column, if the pump has to later be removed for maintenance, the power cable does not have to be untied from the riser. The Boreline and power cable remain attached during retrieval and subsequent installations, making this operation very quick and easy.
At the shaft, the Boreline is handled into position. There are no joints, no welds or no couplings as Boreline is available in continuous lengths. The pump is lowered quickly and safely.
Head works lowered into position
The job is nearly complete as the crane now lowers the top coupling into position.
Boreline in position
The Boreline coupling is resting on a plate at the surface. The coupling and Boreline will support the weight of the pump, pipe and water.
The dewatering process begins as 600 GPM is pumped into an evaporation pond.