Monitoring Kristianstad’s central sewage treatment plant

Author: Frederick Somerville

In order for Kristianstad to be able to grow and meet the needs of the future, a major rebuilding and expansion of the municipality's central sewage treatment plant has to take place. In the ongoing foundation works, there are several challenges. One for example, is that most of the existing pipes and sewers in the plant is in very loose ground as the area was formerly a dried-up lake.

To monitor ground movements, the measurement consulting company Mätrix AB performed monitoring measurements with equipment from Leica Geosystems during the period when piles had to be driven into the ground.

A few hundred meters from the treatment plant in Kristianstad stands Sweden's lowest ground point at 2.32 meters below sea level. “The low level meant that ground conditions at the construction site are one of Sweden's worst”, says Evelina Nilsson, measurement consultant, CEO and founder of Mätrix AB, which is based in Svängsta.

Because the ground conditions are so poor, nearly 1,500 concrete piles had to be being piled into an area where pipes and piping infrastructure already exists. When such extensive piling is performed, careful checks are required as mass movement in the ground can cause shifts and settlements in the surrounding areas. This can be devastating, racking up large costs and damages.

High quality in the result through monitoring

“When we received the measurement assignment, we evaluated a number of possible solutions for how the monitoring could be performed. We came to the conclusion that manual measurements would not give a sufficiently comprehensive result as compared to automated monitoring measurements because so many measurement points needed to be monitored continuously, at frequent intervals and for a relatively long period of time” Evelina explains.

After consulting with Frederick Somerville, Geomatics Technical Support at Leica Geosystems, a customised monitoring solution was created based on the Leica Nova MS50 total station, four Leica Viva GS14 GNSS antennas that Mätrix already owned, a new Leica ComBox for data transmission and the software Leica GeoMoS which controls the measurements and Leica GeoMoS Now! to analyse the data.

In addition, a number of Leica Nivel 220 tilt sensors, were mounted on some of the worksite’s surrounding buildings to check for any effects. Being very sensitive sensors, with a tolerance of 0.0047 mm/m, the Nivel 220 gives very early indications if something is happening to the inclination of the buildings on which they are mounted.

“Initially, we measured in the same way around the clock, but when the piling work turned out to be causing too much disturbance in the total station measurements, we chose during the day to only use the tilt sensors. We set them up such that they sent across movement data every three minutes and the tilt sensors provided results and sounded alarms if something was happening outside the limit values” says Evelina.

“Thanks to the solution, we were able to meet the customer's requirements for accuracy and also get an automated daily report” she adds.

What has been the result of monitoring?

“The measurements showed that there were movements in the ground but that they were manageable and not as large as was initially feared. If we had not performed these measurements however, no one would have known for sure and could only have made assumptions. Thanks to the measurements, it was possible for the piling to be carried out in a controlled manner, which also left everyone feeling secure and in control of the situation.”

The data produced from the monitoring measurements were also of high quality and provided a lot of information.

“With manual measurement, we were able to measure all points but could only repeat the cycle a few times whereas with automated monitoring, we were able to make many measurements of the same points every night” says Evelina.

With the help of the GeoMoS Now! software, all captured data is visualised.

“With GeoMoS Now!, graphs and reports can be easily created for everyone involved in the project and used as the basis for a good analysis. This allowed us to come up with improvement proposals and the geo-technicians could also review the data before making any decisions.”

Saved costs for the customer

A concrete and positive effect of the measurements was that the piling method projected from the beginning could be verified. There was an alternative, more expensive piling method that could have been applied if the ground moved a lot. Thanks to the automated monitoring results, this was avoided, thus preventing any increase in costs.

Another example of saved costs was the securing of a large 1200 mm line which, like a carotid artery, transports all the water from one part of the treatment plant to another.

“If there had been damage to the infrastructure due to a settlement, it would have been a disaster and the entire plant would have had to shut down. Now our measurements could follow the movements and show that that risk did not exist.”

Award-winning innovator and young measurement consulting company

Mätrix AG is a young company founded by Evelina Nilsson in 2014 when she was just 23 years old. Today, it has five employees and is in the process of recruiting two more. In 2020, Mätrix came in third nationally in the Young Entrepreneurs of the Year competition; organised by the trade association Företagarna.

The company profiles itself with a high level of knowledge, innovation and first-class service. Evelina worked in the service trade during her youth and therefore has service mindedness ingrained in her.

“Customer service is very important and we constantly think about our customers' needs. We want to be innovative in a traditional industry and always strive to deliver services with the right quality, the right scope and at the right time. We have fun at work and work closely with each other, brainstorming solutions, ideas and constantly support each other when needed”, she says.

Like the accuracy

Mätrix works mainly with measurement assignments in building production and construction projects with concrete; meaning housing, real estate, industrial buildings and sports facilities.

“We perform a lot of precision measurements and have niched ourselves towards assignments where accuracy is especially important and where a little extra thinking is needed. Personally, I think it's the most fun when it takes a little extra time to get everything right; it really satisfies my sense of order” says Evelina.

All measuring equipment that Mätrix uses comes from Leica Geosystems and they also have a CCP (Customer Care Packages) support agreement.

“We have chosen to buy everything from Leica Geosystems not only because the equipment is of the highest quality but also because they maintain a very high level of service. I think they have a unique personal approach and they always want to give their utmost to us as a customer, regardless of whether it is about finding new solutions, taking care of support matters or complexities to provide the fastest possible help on site.”

Will you continue with monitoring measurement?

“Monitoring measurement in Sweden is on the rise. Many believe that projects must be large for it to be useful but I see that there is great added value even in smaller projects” says Evelina. “It is clearly a service that we at Mätrix AB will want to develop further. It is a good complement in the field of control measurement and that is very exciting.”

Interested in monitoring? Please feel free to read further case studies, showing how our customers use our solution to improve their monitoring workflow:

Monitoring Case Studies