Hampstead Ponds vs the Paddington Arm

A curious title you might think, ‘Hampstead Ponds vs the Paddington Arm.’

What on earth do they have to do with each other? They’re not even related!

At first sight the choice of topic might seem a little strange, however its related to the furore surrounding the Hampstead Ponds dam project. And a bit more than that…

There has been major concern that the Hampstead Ponds could breach and flood communities in the valley areas below the heath. The progenitors of the scheme claim strengthening of the ponds is needed to prevent possible breaches. Local groups are up in arms because they claim the project is a waste of money and damaging the ponds’ heritage.

Protesters at Hampstead Ponds - Source: Camden New Journal

Protesters at Hampstead Ponds – Source: Camden New Journal

The Hampstead project began with the installation of a coffer dam. Ironically the coffer dam began to fail and the communities below the heath were at a higher risk of flooding than they had ever been before! And all this for what is said to be a one in 400,000 years risk of mega-flooding!

Scan from Camden Journal 10 Sept 2015 re concerns on Hampstead dams project

Scan from Camden Journal 10 Sept 2015 re concerns on Hampstead dams project

Now the Paddington Arm. What a contrast! Dozens of miles of canal stretching back to Uxbridge and Slough could potentially flood into the valleys around Paddington, Bayswater – and even Camden! In fact the possibility of such a incidence has not been without substance – it has occurred several times since the canal was built.

The potentiality of this recurring was so great during the Second World War protection was built into the canal. These were known as ARP (Air Raid Precaution) gates** and installed along the entire Paddington Arm (Hayes to Little Venice) as well as elsewhere on London’s waterways.

Double ARP gates at Twyford Abbey bridge, Harlesden (gates disused at the time)

Double ARP gates at Twyford Abbey bridge, Harlesden (gates disused at the time)

For years these gates  have been largely derelict with many presenting a danger to navigation – in 2005 a London based trip boat collided with an ARP gate. Substantial damage was caused to the boat and its passengers suffered injuries. After all the gates were a war time measure and since there was no longer a war on they were uncared for.

Let’s think about it if these gates were indeed not in use or maintained then the potential for flooding Camden could be much greater than the percieved threat from Hampstead Ponds.  The volume of canal water is so infintely greater with a just pair of lock gates at Camden market simply holding back the liquid stuff all the way to Slough with nothing to halt it if the gates at Camden should fail….

The irony between the two situations is at Hampstead (under the control of Camden) there’s people and authorities running around panicking over the idea a couple of ponds could flood London with an almost barely perceptible risk of once in 400,000 years whilst on the other there’s thousands of people not even aware of the possible danger from a 24 mile length of waterway that has flooded several times and the authorites not even batting an eyelid!

Isnt it a good job someone decided to do a repair job at Camden (at the same time open the works up one weekend in November 2013 so us locals could see what was being done) and now they’re restoring the ARP gates.**

These gates at the top of the lock chamber at Camden hold up more than 24 miles of waterway! Seen during the open day November 2013

These gates at the top of the lock chamber at Camden hold up more than 24 miles of waterway! Seen during the open day November 2013

In 2007 British Waterways commenced work to restore and put each of these ARP gates back into use. No doubt BW realised the flood potential for London. The only problem was that British Waterways, as a quango, were subject to stringent funding hence restoration of the ARP gates was put on hold.

Recently the Canal & River Trust saw the light and decided to restore to full operation five sets of ARP gates** as part of its Emergency Response & Water Management Procedures. The work is being done over a couple of years with the first phase this winter (2015/16) at a cost of around £100,000.

**There are 16 ARP sites in the London waterways area. They usually consist of pairs of gates at either end of a section, eg an embankment. The list below denotes the eight located on the Paddington Arm. W/E denotes the direction the gates close in an emergency:

List of ARP gates on the Paddington Arm

List of ARP gates on the Paddington Arm

**This post was originally created by 1LondonBlog

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