“The purpose of the project was to improve the capacity of the local water services by modernizing the underground sewer network. This was done by excavating and reinforcing rock caverns, for example. JIITEE excavated a tunnel on a stretch of approximately 450 meters. The tunnel project at Teollisuuskatu road was tricky owing to its many aspects in a densely built and busy urban environment. The project expanded the old tunnel and made new ones, because it was time the old sewer systems were brought up to modern needs,” says Henri Jokitalo of JIITEE, who’s been working with tunnels for two decades. His current position at JIITEE is that of contract manager.
The project progressed in good cooperation with the contractor and other parties. The overall responsibility for the site was assumed by YIT, with which JIITEE worked in close collaboration. The main contractor coordinated the work stages in the project. JIITEE’s project management also played a major role in making the project successful and organizing the work – a project that lasts eight months calls for plenty of flexibility, scheduling and careful planning.
According to Jokitalo, cooperation was smooth and work progressed really well between the main contractor and JIITEE:
“There were also moments when we had to wait for projects beyond our control to be completed before we were able to continue our work. A project of this magnitude would not be possible without seamless collaboration. The tunnel itself is rather small, and only a few people fit in at the same time.”
YIT Infra
8 months (8/23-4/24)
Subcontractor role for sewer tunnel excavation, reinforcement and compaction, and connections to existing sewer tunnels
12 professionals
JIITEE’s contract also had to take account of work at street level, the local residents, fluency of traffic and uninterrupted metro traffic. Moreover, blasts had to be carried out at times that did not disturb shows in the local theater.
The site was in central Helsinki, and the tunnels were relatively close to the streets and buildings above. No changes had to be made to the scheduling of metro traffic and cultural events, because JIITEE accommodated the blasting based on the demands of the surroundings. During blasting, a close eye was kept on ground vibration.
“We had to take into account continuous traffic in the nearby metro tunnel, and we managed to avoid any traffic disruptions,” says Jokitalo.
According to Jokitalo, JIITEE Työt is quick to embark on new projects:
“Notifications to the authorities, permits, and other practical arrangements always take about two weeks before work can begin. We were able to commit to the Teollisuuskatu sewer project at short notice, and carried out the work on schedule.”
The cost structure was also agreed on at the beginning of the project:
“There were no changes to our initial budget. What we had calculated was also realized.”
The first work stage began at a busy curbside, where the JIITEE team tunneled through the rock towards an existing sewer tunnel, eventually connecting into it.
“When new tunnels are made into an existing sewer tunnel, we had to plan carefully that there were no adverse effects on the current sewer’s operation. The connections were made in the later stages of the project, and the timing was also affected by the water level in the sewer tunnel. The water level must be low enough, and the work cannot be done after heavy rain because of a flooding risk,” says Jokitalo.
“The work took account of varying conditions of the rock, with the designer called in to check the situation if necessary. Work progressed normally in the Teollisuuskatu project, but some rock contusions were discovered owing to the poor quality of the rock. The rock is mainly good, but there were also some parts that included clay and crumbled rock,” says Jokitalo.
JIITEE’s highly professional team is able to take into account rock abnormalities, keeping a close eye on the conditions in order to carry out the work safely. In this particular project, JIITEE occasionally made shorter excavations, pausing to put in extra reinforcement by means of shotcrete or bolting areas with contusions for better safety. This kept the excavations in the planned shape and safe to work in, without making them any larger than was necessary.
JIITEE’s staff is highly committed, and used to working flexibly in various project, appreciating the needs of the projects as a priority. In projects like this, we take into account, depending on the site’s location, matters like fluency of the local residents and minimizing disturbances regardless of the job.
“We were permitted to work for eight months from Monday to Saturday within the limits put in place in terms of noise and rock blasting. From Monday to Friday we worked from 7 am to 9 pm, with shorter hours on Saturdays, and we never worked on Sundays or on public holidays,” Jokitalo explains.
A dozen employees of the JIITEE team were committed to the Teollisuuskatu project. These included a driller and a blaster and maintenance professionals. During excavation, there were first an average of five people at work, with seven to work on the reinforcement.
Jokitalo says that JIITEE’s strength is the ability carry out all parts of the project they undertake. This is possible thanks to their own staff with extensive experience. This is why projects progress quickly and flexibly. Having their own equipment also makes things much easier.
JIITEE is accustomed to various projects that require arrangements for employee safety. The excavation of a sewer tunnel calls for different occupational safety measures than a regular tunnel, because a sewer tunnel in active use contains high levels of bacteria. Once the project got to the stage when JIITEE connected two new tunnels to increase the sewer’s capacity with the existing tunnel, all employees had to be properly vaccinated and use respirators and all necessary personal protective equipment to ensure occupational safety.
We are able to work even in the most demanding conditions and if necessary, innovate completely new solutions to efficiently carry out the work. So don’t hesitate to contact us when you need a professional on site.
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