Vejle Dalen [ENG]

A delicate renewal process within a protected natural environment

At the bottom of the brook ^V\SK IL HSSV^LK [V ÅV^ PU[V [OL IYVVR Renewing the sewage pipe by means of digging was not an option for Vejle Spildevand, as this method would damage the beautiful Mølholm Valley surroundings. At the same time, the question arose about whether it would even have been possible to obtain the necessary derogations regarding the Nature Conservation Act § 3.

The solution was to use the No-Dig method. Vejle Spildevand thus took the KLJPZPVU [V JVVWLYH[L ^P[O 7LY (HYZSLќ ( : 7PWL ;LJOUVSVN` VU [OL L_JP[PUN and highly challenging task, where nature played the main role.

The relining of a sewage pipe beneath a brook running through the beautiful, natural area in Mølmholm Valley in Vejle, Denmark, demanded both a gentle hand and extraordinary planning. This complicated renewal project was successfully undertaken without any damage whatsoever to the environment.

Mølholm Valley is a beautiful natural area located in the south of Vejle. The valley runs between two populated plateaus and is protected by the Danish Nature Conservation Act § 3.

As the local residents of Vejle know it today, the story behind Mølhom Valley began in the early 1970s, when the area around the valley was built. Whilst this construction was being undertaken, a sewage pipe was positioned at the bottom of Mølholm Brook, which runs through the valley. Since then, Mølholm Valley has had the opportunity to develop into a rich natural area, with H [OYP]PUN ÅVYH HUK MH\UH CCTV inspections carried out during the autumn of 2015 revealed that one particular section of the sewage pipe which ran through Mølholm Valley (amongst other places), was in poor condition.

The length of this pipe section stretched 1.5 km. The CCTV inspections revealed WYVISLTZ ^P[O PUÄS[YH[PVU HUK L_[YHULV\Z materials, including tree roots.

“As we are talking about a very vulnerable natural area, we decided to protect both the manholes and the pipe for the future”

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Ulrik Bindeballe Jensen from Vejle Spilde]HUK ( : L_WSHPULK! “As we are talking about a very vulnerable natural area, we decided to protect both the manholes and the pipe for the future.”

During the initial dialogue with the council it became clear that there might IL HKKP[PVUHS ILULÄ[Z [V IL NHPULK I` Z[VWWPUN [OL PUÄS[YH[PVU! TVYL ^H[LY

6UL VM [OL ÄYZ[ PTWVY[HU[ [HZRZ MVY IV[O =LQSL :WPSKL]HUK HUK (HYZSLќ ^HZ [V HWWS` MVY HU L_LTW[PVU ^OPJO ^V\SK allow them to undertake the renovation in a legally protected natural area.

Vejle Council’s Technology and Environment department received the application material from both companies.

According to biologist, Anne Drøgenmüller Lund, the proposed No-Dig method was so gentle, there was no ULLK MVY KLYVNH[PVUZ :OL L_WSHPULK! “The application material showed that they had been out to examine the area, and they selected a method which ^V\SK UV[ HќLJ[ [OL UH[\YHS LU]PYVUTLU[ When the project had ended, I went out to inspect the area, and I was happy to see that there was no damage to the natural surroundings.”

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Gravel path GRØ

Access from Grønnedalen

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Mølholm Brook Renovated stretch

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Bypass-pumping

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Workstation for installation

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End of renovation

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Access to Sønderdalen

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“We knew from the very beginning that we needed to think innovatively, and ZH KDG WR EH KLJKO\ ƃH[LEOH”

Are we really going in there?

“Are we really going in there?” is the X\LZ[PVU [OH[ (HYZSLќ»Z 7YVQLJ[ 4HUHNLY 1HUL 6SZLU HZRLK OLYZLSM [OL ÄYZ[ [PTL she visited Mølholm Valley to plan the project. Initially, she was surprised that such an idyllic, natural environment even L_PZ[LK ^P[OPU H JP[` HYLH 0[ HSZV ILcame obvious to her that such a project KLTHUKLK HU L_[YHVYKPUHY` LќVY[ MYVT all those involved, in order to protect the natural surroundings throughout the duration of the project. Jane Olsen comTLU[LK! “We knew from the very beginning that we needed to think innovatively, HUK ^L OHK [V IL OPNOS` ÅL_PISL ¹

in the valley, including western marsh orchid, cowslip primrose, common club TVZZ HUK THU` V[OLY L_JP[PUN ¶ HUK PU ZVTL JHZLZ YHYL ¶ WSHU[Z Many of Vejle’s local residents use Mølholm Valley for recreational pursuits, such as walking, running and cycling.

Although it is positioned close to the E45 motorway and built-up areas, Mølholm Valley remains a peaceful and calm idyll.

It was within these amazing surroundings [OH[ =LQSL :WPSKL]HUK HUK (HYZSLќ THUaged to work over a period of seven

weeks during August and September 2016.

1HUL 6SZLU L_WSHPULK! “There is no doubt [OH[ ^L ^LYL HSS HќLJ[LK I` [OL MHJ[ [OH[ we were working in beautiful, natural surroundings – and we had such wonderful weather, too.” During the WYVQLJ[ (HYZSLќ»Z LTWSV`LLZ OHK [V HUZ^LY THU` KPќLYLU[ X\LZ[PVUZ MYVT some of Vejle’s residents who had been taken aback by seeing work being undertaken in the middle of their protected, natural environment.

(UK ^OH[ L_HJ[S` PZ P[ [OH[ THRLZ Mølholm Valley so special? It would be easy to say it was merely “nature”; but actually, the area is so beautiful and interesting, every year a series of guided tours arranged by Økolariet, Vejle Council’s science and adventure centre, take place there. According to Økolariet’s Nature Guide, Steen Hedrup, there is an incredible wealth of things to see when L_WSVYPUN 4¥SOVST =HSSL` ,_HTWSLZ VM [OPZ UH[\YHS YPJOULZZ PUJS\KL RPUNÄZOLYZ [YV\[ THU` ZWLJPLZ VM I\[[LYÅ` HUK H IHKNLY»Z I\YYV^ (SS [OPZ MH\UH L_PZ[Z YPNO[ UL_[ [V H WVW\SH[LK HYLH ^OPJO PZ highly unusual. With regard to the area’s plant life, Anne Drøgenmüller Lund JVUÄYTLK [OL L_PZ[LUJL VM V[OLY NLTZ 5

Planning, planning, planning -VY IV[O =LQSL :WPSKL]HUK HUK (HYZSLќ [OL WYVQLJ[ YLX\PYLK L_[YHVYKPUHYPS` KLtailed planning. This was mainly because of the unusually limited access nature VќLYLK ¶ HUK UV[ SLHZ[ VM HSS ILJH\ZL the sewage pipe was located at the very bottom of the brook. This tricky location meant that it was going to be a huge challenge to reach the manholes where, HTVUNZ[ V[OLY [OPUNZ ZP_ *077 SPUPUNZ should to be installed.

“It can be said very simply,” Ulrik BindeIHSSL 1LUZLU L_WSHPULK! “Nature and big machines are not a good match, certainly not in this case, where the existing gravel path running through the valley does not follow the brook, and subsequently not the pipeline, either.” ;OL ÄYZ[ O\YKSL [V V]LYJVTL ^HZ [OL MHJ[ that that the gravel path was too narrow to allow the trucks to come through, and so Vejle Council had to cut down a long WH[O VM [YLLZ ZV [OH[ (HYSZLќ JV\SK SH` app. 1 km of iron plates on the ground.

This work alone took a week, as there was only access for one vehicle at a time on the gravel path. The fact that the path was so narrow was the larg-

“It can be said very simply: Nature and big machines are not a good match”

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est practical challenge over the seven week project period. At the same time, there was no room to set up an area for vehicles to turn around, nor space for storage areas. It thus took a lot of time to coordinate driving and ensure that time was not wasted. Once the iron plates were in place, the sewage pipes and manholes were inspected by CCTV, HUK ^LYL [OLU Å\ZOLK [OYV\NO ([ [OL same time, the manholes along the 1.5 km stretch were uncovered, and bypass-pumping was undertaken.

During the planning phase, both Vejle :WPSKL]HUK HUK (HYZSLќ WVPU[LK V\[ H series of strategic points within the THUOVSLZ ^OLYL [OL ZP_ *077 SPUPUNZ should be positioned. These particular positions were selected as a consequence of their distance to the gravel path. Indeed, the distance to the gravel path was vital as it was not possible to lay iron plates from the path out to the brook, meaning that neither material nor equipment could be transported directly [V [OL THUOVSLZ ;OPZ YLZ\S[LK PU L_[YH HYK\V\Z SHIV\Y MVY (HYSLќ»Z Z[Hќ ^OV spent a great deal of time transporting

material and equipment through areas which were often swampy between the NYH]LS WH[O HUK [OL THUOVSLZ ¶ I` MVV[

In spite of the numerous challenges, the project was still completed in just seven weeks.

0U JVUULJ[PVU ^P[O [^V VM [OL ZP_ *077 installations, it was necessary to place massive rafters across Mølholm brook in order to create the stable base for [OL ZJHќVSKPUN ULLKLK [V Z\WWVY[ [OL installations. The reason was because the two manholes lay at the edge of the brook, which caused further complications and hampered the crane driver’s HIPSP[` [V JVUZ[Y\J[ [OL ZJHќVSKPUN “However, with good planning and clever Z[Hќ [OL [^V PUZ[HSSH[PVUZ ^LYL JVTWSL[ed without problems” Jane Olsen said.

Both Ulrik Bindeballe Jensen and Jane 6SZLU HYL JVUÄKLU[ [OH[ [OL 4¥SOVST Valley project is one that will be remembered for a long time. It was a unique L_WLYPLUJL [V ^VYR ^P[O Z\JO SHYNL machines and vehicles in a delicate natural area with such limited and challenging accessibility. “There were so many things we would normally be able to do that we could not. Often, for example, we are able to drive close up to an installation manhole with all our vehicles and equipment. That was impossible to do here”, L_WSHPULK 1HUL Olsen.

“All in all, it was a very interesting project to be a part of” Ulrik Bindeballe Jensen ZHPK /L HѝYTLK [OPZ ^OLU OL L_WSHPULK how one of the CIPP installations had to be installed from a hilltop using a 35 m long insertion tube. This was done to avoid damage to some trees, which ^V\SK OH]L VJJ\YYLK PM [OL (HYZSLќ [Y\JRZ ^V\SK OH]L KYP]LU UL_[ [V [OL manholes where the installation took place.

<SYPR )PUKLIHSSL 1LUZLU HKKLK! “One thing I will also take with me from the project is the extraordinary cooperation between all those involved. There was absolutely no question that everyone ^HZ ^PSSPUN [V THRL HU L_[YH LќVY[ [V protect nature.”

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”When the project had ended, I went out to inspect the area, and I was happy to see that there was no damage to the natural surroundings”

Project overview Q 1.5 km of relining Q 6 relining installations Q 7PWL KPTLUZPVUZ! DN300 and DN400 mm Q 12 manholes renovated Q The project was carried out over 7 weeks in 2016 Q *VU[YHJ[ ]HS\L! +22 TPSSPVU

Hasselager Allé 5 . DK 8260 Viby Tel. +45 8744 2222 PUMV'HHYZSLќ JVT ^^^ HHYZSLќ JVT

1HU\HY` ;L_[! 1VOU /PYK 7OV[VZ! 1VUHZ (OSZ[Y¥T 3H`V\[! 3HYZ 2\SSILYN

Toldbodvej 20 . DK 7100 Vejle Tel. +45 7641 3700 mail@vejlespildevand.dk www.vejlespildevand.dk