THE logistics of making a hole beneath several layers of rock underneath a 1.5km wide part of the tidal River Severn would seem like an engineer's nightmare.
"But it is the biggest job we have undertaken in this area," he told the Review. "It's quite something."
The new Transco gas main will go under the river from a point mid-way between Sharpness Dock and the site of the old rail bridge on the Eastern bank of the river, beginning from the landward side of the Gloucester-Sharpness Canal.
It will reach the Western bank to the north of Lydney, passing under Wellhouse Rock, and after going under the railway line it will emerge in a field beyond. From there it will be joined to the main pipeline under the A48 road, staying to the north of Lydney.
The problem of making the hole emerge where it is wanted nearly 3km away is solved by modern technology.
"We can't work in the river itself, with its strong tides which mean we would be standing on a mud bank one minute and under water the next," Mr Long told the Review.
"We will send a two-inch pilot drill across, starting from the Sharpness side. It has a sensor in its tip which means means we can actually see where it is going and guide it from a computer screen.
"Provided this goes well we will then be able to attach a reamer to the drill shaft which will open the two-inch hole to 13 inches while it is drawn back from the Sharpness side.
"While it is doing this it will also line the larger hole with soft mud to make it easy for the pipe to come through.
"We will be welding the 12-inch steel pipes into 300m lengths on the Lydney side in preparation. As the reamer and drill are drawn back to Sharpness they will pull a section of pipe after them. When each section comes to its end we will weld another section on and eventually the whole pipe will follow the drill back across."
Mr Long said the plan was to take the pipeline well beneath the rock, mud, sand and silt of the estuary.
"Our geological survey shows that we should be drilling through mud-stone, which is a good medium for us," he said.
"If we go too high the loose material will crumble and cave in."