24 May 2019

Gas main – what gas main?

by: Dave I.

For a long time, we’ve understood the upper limit of navigation for vessels deeper than about 2 feet was the gas main, understood to be too high in the water, and identifiable by a narrows just downstream from Chestnut Lane bridge. A while ago, we were challenged to confirm that restriction, and despite repeated prodding with poles, the whole section seemed to be between 1.0 and 1.5 metres deep. Strange. The powers that be deemed this a trigger for a bigger investigation: please could you sit in a boat in the middle while we empty the water out? Of course we can!

Various folks from WD arrived, folks from the gas main owners arrived, we arrived on Stuart, Ian M opened the paddles, and down we went. Slowly, of course – there’s a lot of water to remove. And down we went. And down we went.

Still no sign of  gas main, but the concrete and stone edging finally emerged on both sides of the cut. Eventually the water level stabilised, grass was hacked down to give better visibility, and various folks used the boat to cross the cut and do the same on the other side
The official gas main markers emerged, and the gas main folks confirmed where the ends were before it dived under the cut.

Still no signs of where and how the main actually crosses the cut, so much discussion ensued. Eventually agreements were made about what we (CCT) could and could not do, and where we could do it. We’ll do some preparatory work, then remove much of the edging, cutting back to the required channel width; then we’ll need to remove debris from the bottom to get to the depth we need – seeing whether that exposes the main in the process. If we still can’t see it, this should be job done, and another obstruction removed from the navigation. If we need to get closer to the ‘keep out’ area, the gas folks will come back to help – time will tell.

It turns out the water level reduction was limited by a large silt bank across the lock entrance – if we need to lower the water further, we’ll need to remove it, or at least cut a channel through it.
After we’d finished, some of us took the opportunity to go further up the pound and look for the sewer – and we could see it this time, just 2-3 inches below water level (it’s the light coloured line from the post in the foreground, going between the 2 posts in the background):

Thanks to Steve for the photos.