View Full Version : Rednought drain, Bristol. 22/08/2009

23-08-2009, 05:52 PM
Rednought is an old red brick storm relief tunnel that runs beneath southern Bristol. It used to be the only storm relief for both the Pigeonhouse and the Malago brooks before a much larger concrete tunnel dubbed Dreadnought was built in the early seventies to replace it further upstream. Rednought is just over 1km in length and discharges into the tidal section of the Avon. Aside from the weather forecast, the tide times need to be checked before planning a trip here. Fresh air is drawn into the tunnel as the tide recedes.

Looking out from the infall. The brook continues through the narrow slot to the left. Just out of shot is a small sluice gate that controls the flow through the channel. The diversion dam is a modern concrete wall with a galvanised steel frame that holds wooden slats. The mud on the other side is about a foot deep and is made of sewerfresh. Your feet sink deep and nasty gas bubbles are released, and I'm sure I could feel something wriggling against my leg when I trod in it.
http://farm4.static.flickr.com/3457/3848153571_6a91d0330e.jpg (http://www.flickr.com/photos/41717334@N05/3848153571/)

A rare subterranean variety of Sainsbrus Asdatum, a common aquatic plant indigenous to the UK. These naturally grow in rivers and canals and are harvested by supermarkets for use as shopping trolleys. These recently deposited debris show that Rednought still carries a significant flow at times of high water in the brook.
http://farm3.static.flickr.com/2533/3848153575_5dedb8d56c.jpg (http://www.flickr.com/photos/41717334@N05/3848153575/)

An iron deposit that has almost filled the sidepipe it emerges from.
http://farm4.static.flickr.com/3446/3848153583_58324cd0a8.jpg (http://www.flickr.com/photos/41717334@N05/3848153583/)

A large portion of the flow in the upstream section is from this concrete sidepipe. Daylight can be seen from a junction a short way up. The adjacent plastic pipe is filled with grit.
http://farm4.static.flickr.com/3466/3848153589_ac070e7c62.jpg (http://www.flickr.com/photos/41717334@N05/3848153589/)

This short section is covered by concrete slats. It may have been an open section in the past.
http://farm3.static.flickr.com/2490/3848153595_299d4c1a2f.jpg (http://www.flickr.com/photos/41717334@N05/3848153595/)

A rusted ladder inside one of several abandoned manhole shafts.
http://farm4.static.flickr.com/3466/3848153597_536010fae0.jpg (http://www.flickr.com/photos/41717334@N05/3848153597/)

A short section of the tunnel lies below the water table and groundwater pours in from all directions.
http://farm3.static.flickr.com/2589/3848951008_ae5c9ef6cf.jpg (http://www.flickr.com/photos/41717334@N05/3848951008/)

A narrow opening leads to an access chamber with a large steel downpipe that terminates at a rest bend which exits into the tunnel.
http://farm3.static.flickr.com/2638/3848951016_0b7bf0bfdd.jpg (http://www.flickr.com/photos/41717334@N05/3848951016/)

The pipe is abandoned and has been filled with cement.
http://farm3.static.flickr.com/2486/3848951018_9414362282.jpg (http://www.flickr.com/photos/41717334@N05/3848951018/)

This small CSO outfall is the primary source of the sewerfresh smell in the tunnel.
http://farm4.static.flickr.com/3481/3848951026_79cf045881.jpg (http://www.flickr.com/photos/41717334@N05/3848951026/)

A ladder leads to a concrete access chamber. The overhanging debris suggest that there is another CSO up there too.
http://farm3.static.flickr.com/2500/3848951032_e8451132b5.jpg (http://www.flickr.com/photos/41717334@N05/3848951032/)

Leg irons at the base of another abandoned access shaft. Stone slabs cover this shaft a short distance up, and groundwater seeps in from beneath them.
http://farm3.static.flickr.com/2616/3848951038_9150142b57.jpg (http://www.flickr.com/photos/41717334@N05/3848951038/)

More groundwater flows in close to the beginning of the muddy tidal section.
http://farm3.static.flickr.com/2602/3848955358_c3b3bfa844.jpg (http://www.flickr.com/photos/41717334@N05/3848955358/)

A modern concrete access shaft has been added at a very deep section of the tunnel.
http://farm3.static.flickr.com/2459/3848955370_e8fafc5519.jpg (http://www.flickr.com/photos/41717334@N05/3848955370/)

The tunnel returns to a relatively dry state closer to the outfall. I have no idea what this piece of plywood is doing bolted to the wall, or what lies behind it.
http://farm4.static.flickr.com/3532/3848955376_f0a4712824.jpg (http://www.flickr.com/photos/41717334@N05/3848955376/)

An electric cable hangs from another abandoned manhole shaft from which the ladder has been removed. Was there lighting down here once?
http://farm3.static.flickr.com/2520/3848955386_969361f9d8.jpg (http://www.flickr.com/photos/41717334@N05/3848955386/)

A four foot prefab concrete pipe joins the tunnel close to the outfall, but it appears to lead to a dead end.
http://farm3.static.flickr.com/2526/3848955390_a111a2a065.jpg (http://www.flickr.com/photos/41717334@N05/3848955390/)

A substantial length of the tunnel is filled with river water at high tide and this section has allot of mud deposited along the walls.
http://farm4.static.flickr.com/3506/3848955396_54cecdf7e0.jpg (http://www.flickr.com/photos/41717334@N05/3848955396/)

The end. Beyond the flap is a muddy waterslide down the south bank of the Avon.
http://farm4.static.flickr.com/3435/3848958124_2585583bcd.jpg (http://www.flickr.com/photos/41717334@N05/3848958124/)

The outfall chamber is a modern concrete job with a platform that might contain the sluice workings. I wanted to climb the ladder, but I really didn't fancy tackling the mud in trekking sandals.
http://farm3.static.flickr.com/2634/3848958132_6741394cff.jpg (http://www.flickr.com/photos/41717334@N05/3848958132/)

There seems to be a smaller tunnel behind another sluice gate in the outfall chamber, but the gate is closed and mostly buried in the mud.
http://farm3.static.flickr.com/2602/3848958134_7ed375e288.jpg (http://www.flickr.com/photos/41717334@N05/3848958134/)

After leaving Rednought I walked on to Dreadnought as apparently "access has been made rather easy". This usually means that some See You Next Tuesday has gone and broke the lock off. However upon arrival at the Pigeonhouse infall I found that Wessex Water had got there first, and a nice new high-security stainless steel padlock was holding the access hatch firmly shut. Normally this means Plan B, but without manhole keys and a strong lifting buddy it was clear that I wasn't getting in. Admitting my defeat with this one I started the long plod back to the station. If anyone needs a teaboy on their next Dreadnought trip, you know who to call ;)

24-08-2009, 03:26 PM
An interesting report :thumb, that yet again reminds me why I'm not going down any drains ever ;).

^ This. I've grown up alongside the river avon and still the tidal patterns scare me.

24-08-2009, 04:30 PM
Yes nicely reported and for me the thought of the water suddenly rushing back in there fills me with dread - nice to see pics but not go there :)

24-08-2009, 07:54 PM
Indeed, the Avon tide is very high and very fast. Furthermore, high tide can be several feet above the roof of the tunnel at the outfall end. I printed a copy of the tidal forecast for Avonmouth and took it with me, and timed my visit so that I entered the drain as the tide was receding and was heading back to the infall before the tide had turned so as to avoid the watery death-race altogether. I understand your fear of being chased back up the tunnel by the the rising water though - the incoming tide is quite unsettling when you see the river flowing the wrong way so close to the weir.

24-08-2009, 08:38 PM
Don't ever want to swallow any of the water. In some of the local regattas I particpated (on the river mouth by Avonmouth) - the guidance was you needed to go straight to hospital if you swallowed any of the lovely brown syrup.. and to think as boys we used to swim in the creek!

24-08-2009, 08:56 PM
Great report.

I would feel so claustrophobic and more than a little worried that a dam may burst somewhere upstream and I would be swept away by a tidal wave............or do I watch too many disaster movies :lol:

25-08-2009, 08:55 AM
That is a great report mate, and cool pictures indeed. I do like the first and last shot :thumb

27-08-2009, 06:21 PM
Bit messy for my liking! I commend you on a great effort!

28-08-2009, 06:20 PM
Im off to look at this tomorrow with a few other drains in bristol if anyone fancys tagging along with me a a few others.

28-08-2009, 06:41 PM
Good job your not going today.. Bristol = Car Park at the moment.

Remember there is football on at 3pm tomorrow around BS3

28-08-2009, 08:21 PM
yeah four hours from swindon to avonmouth, bloody jumper on avonmouth bridge.....

28-08-2009, 09:33 PM
yep, sadly the bloke fell to his death just after 7.30

06-09-2009, 08:10 PM
Im off to look at this tomorrow with a few other drains in bristol if anyone fancys tagging along with me a a few others.

How did you get on? Did you climb them ladders? :thumb

06-09-2009, 09:43 PM
Did dreadnaught, sevalco, but couldnt get half the team into motherload, and run out of time for rednaugh, will be back though.