When the Grand Junc­tion Canal opened, its Tring sum­mit needed a wa­ter sup­ply. It still does. We fol­low the story through 200 years to to­day’s pump up­grades

Canal Boat - - CONTENTS -

In an ideal world, canals wouldn’t need pumps to sup­ply their wa­ter – and many don’t. Pro­vided with ad­e­quate reser­voirs, of­ten tucked away high in the hills some miles away, they can draw on enough sup­plies by grav­ity alone to see them through a typ­i­cal sum­mer, be­fore the win­ter rains re­plen­ish ther stocks.

Other canals are less well-equipped with sup­plies which over the years, as the canals got busier, needed to be sup­ple­mented with back-pump­ing schemes, re­turn­ing wa­ter used by lock op­er­a­tion back up to the sum­mit level for re-use. In re­cent years, the re­vival of the canals for leisure led to sev­eral of these sys­tems be­ing re­in­stated or new ones in­stalled, for ex­am­ple en­abling wa­ter to be pumped all the way east up the Ken­net & Avon from Bath to the sum­mit at Woot­ton Rivers, or right through from the Black Coun­try to the south­ern Grand Union.

But there’s an­other pos­si­ble rea­son for canal wa­ter sup­plies to need pump­ing – and not just in dry sum­mers when it runs short. Oc­ca­sion­ally, the lo­cal ge­og­ra­phy meant that it wasn’t pos­si­ble to find wa­ter sup­plies (or to find suitable sites for reser­voirs to store the wa­ter) suf­fi­ciently high up to feed the canal’s high­est lev­els. There might be no al­ter­na­tive but to site the reser­voirs at a level where wa­ter would need to be rou­tinely pumped out of them and up into the canal.

We caught up with the Canal & River Trust’s Charles Baker, who is fa­mil­iar with such sit­u­a­tions. In his role as Se­nior Project Man­ager for the Lon­don & South East Re­gion with a fo­cus on me­chan­i­cal, electrical and pump­ing equip­ment, he and his team have got two of them on their patch. They’re both the sub­ject of cur­rent ma­jor works which, as he ex­plains is aimed at keep­ing them per­form­ing their vi­tal func­tion by match­ing up mod­ern tech­nol­ogy (in the form of new elec­tric pumps) to the his­toric in­fra­struc­ture dat­ing back to the days when the job was done by coal-fired beam en­gines.

One of these is on the Ken­net & Avon, and re­sults from a dilemma faced by the canal’s 18th cen­tury plan­ners. Ide­ally they would have liked a long, rel­a­tively low level sum­mit run­ning all the way from Crofton through to De­vizes, a dis­tance of 20 miles at an al­ti­tude where sup­ply­ing it with wa­ter by grav­ity from lo­cal springs and streams wouldn’t have been an is­sue. But that would have needed a tun­nel 4312 yards long (which would have been sec­ond only to Stand­edge on the Hud­der­s­field Canal as the coun­try’s long­est), adding to the cost, dif­fi­culty and time taken for the work. So in­stead, they opted for ex­tra locks lead­ing up to a shorter higher sum­mit level with a much shorter tun­nel – but that meant climb­ing to a height where no wa­ter sup­plies were avail­able.

The solution was to raise wa­ter from a lower level (and later from a reser­voir Wil­ton Wa­ter - con­structed at that level) up to the sum­mit by the cel­e­brated Crofton Pump­ing sta­tion, whose re­stored beam en­gines still carry out their orig­i­nal func­tion on cer­tain sum­mer week­ends. For the rest of the time, the job is done to­day by elec­tric pumps, but still us­ing Wil­ton Wa­ter and still feed­ing into the same leat (wa­ter sup­ply chan­nel) lead­ing to the sum­mit level that was built to serve the steam pumps. CRT is cur­rently part way through a pro­gramme of re­place­ment of the elec­tric pump­ing sys­tem in use since the canal was re­stored 30-plus years ago. Read­ers may re­mem­ber that their re­li­a­bil­ity went un­der the spot­light a few years ago when the steam pumps had to be fired un­ex­pect­edly thanks to the fail­ure of their mod­ern re­place­ments.

The project is di­vided into three stages: the first part, re­plac­ing the pipe­line across the pump­ing sta­tion site, has al­ready been com­pleted. The sec­ond, the re­place­ment of the elec­tric pump­ing sta­tion, is due to take place this sum­mer, with the fi­nal phase re­place­ment of the pipe run­ning un­der the canal bed from Wil­ton Wa­ter – due to start in the au­tumn.

At the same time, Charles de­scribes a wider project known as “K&A Re­silience” also un­der way. Up to now, the Crofton pumps plus the var­i­ous back­pumps in­stalled

to re­cir­cu­late wa­ter past the locks at Bath, Brad­ford-on-Avon, Seend, Sem­ing­ton, De­vizes and Woot­ton Rivers have tended to be treated in iso­la­tion with be­spoke solutions at each site. The lim­i­ta­tions of this ap­proach were shown up when one of the big­gest pumps, rais­ing wa­ter past the mighty 29-lock Caen Hill flight at De­vizes, failed – and turned out to be pretty much the only pump in Europe of that par­tic­u­lar com­bi­na­tion of man­u­fac­turer, size and type. Re­pairs to the orig­i­nal be­ing im­prac­ti­ca­ble, a re­place­ment was sourced, but it too is ‘on lim­ited time’ re­gard­ing re­place­ment parts. So the aim is to even­tu­ally re­place all the back­pumps with de­signs which are not only suited to the in­creased use since the sys­tem was set up, but have a high de­gree of trans­fer­abil­ity be­tween sites.

But that’s some­thing of a di­gres­sion into back­pump­ing. Go­ing back to the is­sue of canals whose sum­mit level can­not be fed by grav­ity and which there­fore rely on pump­ing just to pro­vide them with their reg­u­lar sup­ply from the reser­voirs, we come to the sec­ond such ex­am­ple on Charles and his team’s patch: on the south­ern Grand Union at Tring. And com­pared to the sim­ple sys­tem at Crofton of one reser­voir, one pump­ing sta­tion and one canal, it’s a whole lot more com­pli­cated...

Once again, the ge­og­ra­phy dic­tated that a con­ven­tional reser­voir feed­ing into the sum­mit level wasn’t an op­tion. The por­ous chalk ground con­di­tions meant that there was very lit­tle in the way of streams or other sur­face wa­ter above the level of the canal’s three-mile sum­mit (most of it in a deep cut­ting) from Cowroast to Bul­bourne. In­stead of reser­voirs, a seven-mile feeder was built to bring sup­plies in from springs fur­ther west along the hill­side near Wen­dover. To cater for trade from Wen­dover, it was built large enough to be nav­i­ga­ble.

As trade on the new canal built up, this sup­ply soon be­came in­suf­fi­cient to keep the canal go­ing through the drier sum­mer weather, so in 1802 a reser­voir was built on a suitable site some way down the hill­side from the Wen­dover Arm at Wil­ton. In wet­ter weather, it was fed by a chan­nel bring­ing any sur­plus wa­ter com­ing in along the arm, plus some lo­cal springs - and in drier weather the stored wa­ter was pumped back up into the arm (and so to the main line) via a ‘head­ing’ (an un­der­ground cul­vert) lead­ing from the bot­tom of the reser­voir to White­houses, where a steam pump raised it up a well-shaft and into the Arm.

Such was the suc­cess of the canal that the in­creased needs for wa­ter saw three fur­ther reser­voirs built over the next four decades – Star­topsend, Mar­sworth and Tring­ford – plus two more pro­vid­ing in­creased ca­pac­ity at the orig­i­nal Wil­stone site. The new reser­voirs were all fed by springs and by sur­plus wa­ter from the Wen­dover Arm in win­ter, while in sum­mer two fur­ther pump­ing sta­tions at Tring­ford and Bul­bourne raised the stored wa­ter into the Arm.

In the late 1830s pump­ing was con­cen­trated on the cen­tral sta­tion at Tring­ford, with new head­ings en­abling it to draw wa­ter sup­plies from all the reser­voirs, and the White­houses and Bul­bourne pumps abol­ished. While this was a sen­si­ble ra­tio­nal­i­sa­tion, it did cre­ate what we would now call a ‘sin­gle point of fail­ure’ in the form of the sin­gle Tring­ford pump. So a sec­ond pump was added, pump­ing from a sec­ond well-shaft.

These two pumps sat­is­fied the canal’s needs right up into the 20th cen­tury, but in the mean­time an­other is­sue was mak­ing it­self felt. The por­ous chalk soil that it had passed through had al­ways caused leak­age prob­lems on the Wen­dover Arm – in par­tic­u­lar the length from Tring­ford to Dray­ton Beauchamp – and it was get­ting worse. At times it had leaked so badly that far from act­ing as a feeder, it was ac­tu­ally tak­ing wa­ter away from the main line. Var­i­ous meth­ods of lin­ing it were pro­posed and some of them tried, but af­ter a pe­riod

dur­ing which this length was drained, dammed off, and the canal had to rely largely on the Wil­stone reser­voirs (which were fed from be­yond the far end of the leaky sec­tion), a re­port in 1910 led to more dras­tic mea­sures be­ing taken.

The Arm was closed to nav­i­ga­tion, the wa­ter level of most of it was low­ered (to be­low the level of some of the leaks), and the Tring­ford to Dray­ton length was drained. A pipe­line was laid (mostly buried in the drained canal bed), to con­nect sup­plies com­ing down the Arm to the Tring­ford reser­voir and to the pump­ing sta­tion where a third well-shaft (con­fus­ingly now re­ferred to as No 1) was dug and a third pump added (and 30 years later in 1944, a fur­ther pump in a sep­a­rate build­ing, to pump wa­ter di­rectly from the pipe­line into the Arm next to the pump­ing sta­tion). Mean­while the old steam pumps, which had done the job re­li­ably for 100 years but were in­her­ently hun­gry on fuel, were re­placed by elec­tric ones, ini­tially sup­plied by on-site diesel gen­er­a­tors.

And that’s more-or-less how things have run since then. But in re­cent years two is­sues have arisen: firstly those pumps have been show­ing their age. And se­condly thanks to the ef­forts of the Wen­dover Arm Trust, the dry length of the Arm is grad­u­ally be­ing given a wa­ter­proof lin­ing and will in due course (along with the re­main­der of the Arm to Wen­dover) be re­stored to nav­i­ga­tion.

Mat­ters reached a se­ri­ous state in re­cent times, lead­ing to the cur­rent project to se­cure this vi­tal part of the south­ern GU’s wa­ter sup­ply sys­tem for the fu­ture. The pump in the No 2 well (which can sup­ply the canal from any of the reser­voirs) hasn’t been op­er­a­ble since around 2007. For the pump-spot­ters among you it’s a Rees Ro­turbo from 1911 pow­ered by a City Electrical mo­tor, and sadly it was re­garded as be­yond re­pair. More re­cently the No 3 well pumps (also ca­pa­ble of draw­ing on any of the reser­voirs), an­other pair of slightly younger (1927) Rees Ro­turbo pumps but pow­ered by mo­tors from Lan­cashire Dy­namo, also failed – and at present a tem­po­rary pump is re­plac­ing them. And fi­nally, the No 1 pump (which can only pump from Tring­ford Reser­voir), a Sykes with Comp­ton Parkin­son mo­tor dat­ing from a re­place­ment in 1960, is cur­rently out of ser­vice and un­der re­fur­bish­ment.

At the same time the pipe­line un­der the dry bed has been taken out of ser­vice owing to leaks: in due course it will no longer be needed, as once the Wen­dover Arm is re­opened the wa­ter can flow straight through to the Main Line like it orig­i­nally did. But that’s a lit­tle way off, and in the mean­time the old head­ing which once linked the for­mer White­houses pump to Wil­stone Reser­voir it be­ing put back in ser­vice to con­tinue its func­tion. This is a good ex­am­ple of the 19th cen­tury meet­ing the 21st, as a state of-the -art ROV (Re­motely Op­er­ated Ve­hi­cle – Charles de­scribes it as ba­si­cally “an un­der­wa­ter drone”) was sent up the head­ing un­der re­mote con­trol to check its con­di­tion, and it’s now in use.

The ma­jor part of the project has been to re­place the No 2 pump. Two new pumps have been sourced, and are cur­rently be­ing in­stalled such that one can be kept on standby and eas­ily switched over for ser­vic­ing, in case of a fault, and to pro­vide a longer life­span be­fore the next re­fur­bish­ment or re­place­ment is needed. They will ful­fil the main pump­ing re­quire­ment. At the same

time, the No 3 pumps have been taken out and will be pre­served within the build­ing as non-func­tion­ing his­toric arte­facts – and that’s a re­minder that the build­ing’s a listed struc­ture, with a lot of his­toric fea­tures dat­ing from its steam, diesel and elec­tric eras - al­though it’s also seen many changes, such as the re­moval of the up­per storey of the build­ing when it was no longer needed to house the beams of the steam en­gines.

Fi­nally, one his­toric arte­fact which will re­main in use once re­fur­bished is the No 1 pump from 1960, which will con­tinue to pro­vide sup­ple­men­tary ca­pac­ity pump­ing from Tring­ford Reser­voir.

So next time you’re cruis­ing past on the Grand Union, take a de­tour along the Wen­dover Arm to Tring­ford. Just be­fore the ter­mi­nus (you can now turn a ful­l­length boat there, thanks to WAT’s restora­tion progress), look out for a brick build­ing half-hid­den by veg­e­ta­tion on your right, near an old stop-lock. That’s the pump­ing sta­tion, built for beam-en­gines in the early 19th cen­tury, and still the heart of a pump­ing scheme where mod­ern equip­ment is work­ing with 200-year-old reser­voirs, cul­verts and wells to (hope­fully) keep the Grand Union from run­ning dry.

The elec­tric pumps in Tring­ford No 3 Well, dat­ing from 1927

...and dur­ing the re­build­ing af­ter con­ver­sion to elec­tric power

...and as it was when it still housed steam pow­ered beam-en­gines...

The Tring­ford pump­ing sta­tion build­ing to­day...

The old­est elec­tric pump dat­ing from 1911 is re­moved from pump well No 2

Be­yond re­pair: a shaft from one of the No 3 pumps

Look­ing down into the No 2 pump well: the shower of sparks is from re­moval of steel­work from the old pump

Mak­ers’ plate from the mo­tor of one of the No 3 pumps

1940s plan of the reser­voirs and con­nec­tions. Re­port and plans have been use­ful for the cur­rent work

Plans from a 1940s re­port for the Grand Union com­pany: de­tails of Tring­ford

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