PILES, POPLARS AND PUMPS
Piles, poplars and pumps were but a few of the many challenges which the wastewater company Vejle Spildevand A/S were facing in the autumn of 2014, when water from an important sewer pipe was seen breaching the surface of the asphalt in a busy intersection in the city of Vejle. A very important pipe It was September of 2014 when Vejle Spildevand A/S became aware that water had breached the asphalt of a busy intersection in the northern part of the port area of Vejle. It became apparent that the cause was a leaking well. “We naturally reacted immediately, as two important sewer mains meet at precisely this intersection of Langelinie and Strandgade,” says Ole Glavind, Vejle Spildevand A/S. One of the two sewer mains is a pressure main, transporting rain and wastewater from Bredballe, which is a small town on the northern bank of Vejle Fjord. The other sewer main transports wastewater from an area north of Vejle Fjord, which among other things includes the small town of Grundet and a large Tulip food processing factory. This sewer main is special, as it is basically a gravity pipe. But a slope of more than 50m means
that the water is under pressure when it reaches the intersection of Langelinie and Strandgade. An array of challenges Initial investigations showed that the two mains which meet at the intersection were intact. It was the well and a pipe which runs from the intersection approximately 950m to the main water treatment plant in the port area of Vejle which constituted the problem. The pipe is constructed of reinforced concrete and was established in 1978/1979. One of the primary challenges was the location of the pipe. Large sections of the pipe lie just 0.5m from a drinking water main of 500mm in diameter which has a direct connection to the two water towers involved in Vejle’s water supply. At the same time the soil conditions are unusual, in that H Z[YLHT =LQSL g ÅV^Z [OYV\NO [OL area. Consequently the pipe crosses Vejle Å at a depth of a few meters quite close to the stream’s mouth in Vejle Fjord. Parts of the pipe are at a depth of 4-5m, but most of the pipe lies at a depth of approximately 2m. Its location close to Vejle Å means that the soil conditions are unusual and that parts of the pipe are supported by piles in a trench in common with the water main, in order to compensate
No-Dig pipe line renewal among silver poplars
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for the silt-like conditions of the soil. Furthermore, the pipe runs through a WVW\SV\Z HYLH ^P[O H SV[ VM [YHѝJ It turns out that approximately the last 225m of pipe approaching the water treatment plant was in very poor condition due to corrosion. “It was quickly abundantly clear that this was where we needed to begin. It was also clear that No-Dig pipe lining was the only feasible opportunity in terms of securing the integrity of the 225m section for the future. So we started the planning process in close JVVWLYH[PVU ^P[O 7LY (HYZSLќ ( : Rørteknik” says Jakob Ejskjær, Vejle Spildevand A/S. Had Vejle Spildevand A/S chosen a solution requiring excavations there would no doubt have been negative consequences for both the drinking water main and the piles. “Excavation was simply not a reasonable alternative. It would have had unforeseeable consequences, not least due to the soil conditions and water table considerations,” says Ole Glavind, Vejle Spildevand A/S. “With No-Dig pipe lining we could solve the problem in about three days. Had we chosen a solution involving excavations, it would probably have taken us three months.”
Langelinie/ Strandgadeintersection
Valve chamber
New well. Installation point
Silver poplars
Vejle
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Indhegnet P-plads 225 m pipelining
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Reinforced challenges Early in the planning stage it became clear that it would not be possible to gain access to the 225m section from one of the existing wells. This was due to the fact that the nearest well was approximately 360m distant. Moreover there was a vertical bend, as well as a number of horizontal bends in the pipe because it runs under Vejle Å. It was therefore necessary to establish an entirely new well from which to install the No-Dig pipe lining. ;OL ÄYZ[ Z[LW [V^HYKZ H UL^ ^LSS
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New well. Installation point Silver poplars
In November of 2014 the company Østergaard A/S commenced the work of establishing a well above a bend in the pipe only 15-20m from the stream. Østergaard A/S started by installing a trench box. The bend in the pipe was constructed as a 30-degree bend encased in a large box-shaped casting, which resulted in particular challenges, as it was impossible to know beforehand precisely where the pipe lay inside the casting. Nonetheless, a hole was successfully made in the correct place. The pipe was unusually strongly reinforced and it therefore took several hours to open a hole in it with the help of a diamond cutting tool and a pneumatic drill. “We managed, as planned, to LZ[HISPZO [OL UL^ ^LSS ÄUK [OL WPWL in the casting and cut a hole in it. But it was a bigger challenge than we had anticipated,” says Troels Larsen of Østergaard A/S.
Fenced in parking lot
The main has been marked. Next step: opening a hole
225 m pipe lining
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However, Østergaard A/S were not yet done with their work on the pipe, as the hole in the pipe needed to be completed immediately before the installation of the pipe lining, because a bypass system at that time would have drained the pipe. Goodbye to the poplars – for a while The new well was placed among a number of silver poplars close to a public parking lot. The silver poplars are among the motifs artist Ingvar Cronhammer included in his works of art in the area
surrounding the main water treatment plant in Vejle. In order to create enough room for [OL THJOPULY` ULLKLK I` 7LY (HYZSLќ A/S, Rørteknik for the installation and the curing of the 13-ton pipe lining, it ^HZ ULJLZZHY` [V YLTV]L Ä]L T poplars. These, however, were subsequently replanted. Entry into the area was also a challenge, and Vejle Spildevand A/S decided to remove a stretch of the fencing surrounding the water treatment plant, as it would otherwise have been impossible for trucks to access the area where the installation was
taking place - an extra advantage of this decision was that the cleaning of the pipes before installation could be completed much more quickly, as the distance to the unloading area was ZPNUPÄJHU[S` YLK\JLK On the 4th of February Østergaard A/S completed the hole in the pipe HUK (HYZSLќ ( : 9¥Y[LRUPR JV\SK install the pipe lining. The installation was conducted to plan over three days. The pipe lining was cured with the help of water from Vejle Å.
>OLU [OL ^LSS ^HZ ÄUPZOLK it was time to replant the silver poplars
The hole in the sewer main YLZ\S[LK PU ÅVVKPUN
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Naturally it was not only around the well that there was great activity. The intersection of Langelinie/ Strandgade also saw hectic work. It was necessary to establish a large bypass system, which among other [OPUNZ YLX\PYLK JSVZPUN Vќ H ZLJ[PVU VM Langelinie. ;OPZ YLYV\[PUN VM [YHѝJ ^HZ KVUL PU close cooperation with the Municipality of Vejle, which among other things ensured that residents and I\ZPULZZLZ HќLJ[LK I` [OL ^VYR ^LYL PUMVYTLK VM [OL UL^ [YHѝJ ZP[\H[PVU 0U NLULYHS [OL JSVZPUN Vќ VM a stretch of Langelinie did not cause great problems due to the other convenient alternative routes drivers could make use of.
with the bypass system, and it was therefore important that the whole project be completed during a period of no rain. “We naturally kept an eye on the weather reports, and our WSHUUPUN OHK I\PS[ PU ÅL_PIPSP[` PU [LYTZ of time, in order that we could install under optimal weather conditions. Luckily we had good weather and we could execute the installation under sunny skies,” says Hans Bodilsen, 7LY (HYZSLќ ( : 9¥Y[LRUPR
“We received absolutely no complaints related to the bypass system or redirected [YHѝJ ¹ says Ole Glavind.
A drained pipe – an opportunity too good to miss While the bypass system was running, Vejle Spildevand A/S exploited the opportunity to clean and inspect – by CCTV – the rest of the damaged pipe. Actually, the bypass system was extended by 5-6 hours, which made it possible to complete a thorough inspection of the pipe.
The entire project was dependent on the weather. The large amounts of water from the two mains which meet at the Langelinie/Strandgade intersection were pumped into a 1.7m diameter combined sewer main in the area. This main’s capacity was exploited to the full in connection
It was established that some stretches of the pipe were in good condition, while others would need to be improved within the timeframe of a few years. Pipes which drain sections of bypass pumping and alternate between full and half full are slowly LH[LU H^H` I` O`KYVNLU Z\SÄKL
Process tubes for heating and thus curing of the pipe lining
Additional installation equipment
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It is therefore always a good idea to examine such pipes regularly. Vejle Spildevand A/S also conducted maintenance work on two valve JOHTILYZ ;OPZ ^HZ KPѝJ\S[ ^VYR MVY [OL TL[HS^VYRPUN ÄYT ^OPJO KPK [OL job. The valve chamber’s upper lid was 600mm in diameter while the lids down in the chamber were 700mm in diameter, and therefore the 700mm lids were halved and PE welded down in the wells. That meant that the metalworkers had to lie prone on the ground and weld the lids together down in the wells. Three days later Just three days after the work to install the pipe lining had started Vejle Spildevand A/S could replant [OL Ä]L ZPS]LY WVWSHYZ YLWHPY [OL MLUJL and generally rehabilitate the area surrounding the new well. The 225 meters of pipe which underwent No-Dig pipe line renewal will last for many years – now there HYL UV QVPU[Z HUK UV O`KYVNLU Z\SÄKL corroding the pipe. Neither are there disturbances VM [YHѝJ VY [OL KH` [V KH` I\ZPULZZ of the city’s residents.
Pipe lining using installation tower
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“With No-Dig pipe lining we could solve the problem in about three days. Had we chosen a solution involving excavations, it would probably have taken us three months�
“We received absolutely no complaints UHODWHG WR WKH E\SDVV V\VWHP RU UHGLUHFWHG WUDIĆ‚FĹ”
Toldbodvej 20 . 7100 Vejle mail@Vejlespildevand.dk . www.vejlespildevand.dk
Lokesvej 15 . 8230 Ă…byhøj. Tel. +45 8744 2222 PUMV'HHYZSLŃœ JVT ^^^ HHYZSLŃœ JVT
April 2015 . Text: John Hird . Photos: Palle Skov . Layout: Lars Kullberg
“We naturally kept an eye on the weather UHSRUWV DQG RXU SODQQLQJ KDG EXLOW LQ ĆƒH[LELOLW\ LQ terms of time, in order that we could install under optimal weather conditions. Luckily we had good weather and we could execute the installation under sunny skiesâ€?