Blominmäki sewer excavations

The excavation of sewage tunnels is mainly carried out after cave system excavations beginning from 2018. In Mikkelä, the sewage tunnels were excavated in 2017 from the Mikkelä access tunnel to south of the Espoo River. Look map at zoomable version (pdf, 15Mb)

See also: Frequently asked questions concerning sewer tunnel excavation

Mikkelä ll, Eestinkallio and Malminmäki

Kalliorakennus-Yhtiöt Oy is the main contractor for the three contracts for the construction and excavation of the wastewater treatment plant's inlet and outlet tunnels. The contracts are Mikkelä ll, Eestinkallio and Malminmäki. The southernmost part of the inlet and outlet tunnels, Finnoo, will be tendered later.

The inlet and outlet tunnels run from Mikkelä to Suomenoja. The total work time of the tunnels is 2/2018-3/2021. The tunnels are about 4.5 meters wide and 5.5 meters high. The length of both tunnels is about 7 kilometers. Tunnel excavation progress is about 10 meters per day.

In Mikkelä, tunnels were excavated already during the sewage treatment plant's excavation stage, so work can be started directly with tunnel excavation week 12/2018. In Eestinkallio and in Malminmäki, tunnels are also built and excavated for maintenance connections which operate as driving tunnels in the excavation stage. At these sites, the work begins with earthwork and open-cast excavations, which are scheduled to start week 14/2018. After the above-ground work is completed, tunnel excavation begins.

Working hours

Above-ground work:

  • on weekdays 7:00-18:00, and if necessary, also 18:00 to 21:00 (after 18:00 below 35dB)
  • on Saturdays 9:00 to 18:00 (under 35dB)

Underground work:

  • on weekdays 7:00-18:00, and if necessary, also from 18:00 to 22:00 (after 18:00 below 40dB)
  • weekends and midweek holidays from 9:00 to 22:00 (under 35dB)
  • if necessary on weekdays from 22:00 to 7:00 or on weekends and midweek holidays from 22:00 to 9:00 (less than 30dB)

Tunnel blasting:

  • Monday to Friday from 7:00 to 22:00
  • Saturdays from 9:00 to 18:00

The loading and transport of blasted rock from the tunnel:

  • weekdays from 7:00 to 22:00, weekends and midweek holidays from 9:00 to 22:00
  • if necessary on weekdays from Monday to Friday from 22:00 to 7:00, as well as weekends and midweek holidays from 22:00 to 9:00

The exact dB level refers to the indoor noise level of a residential building, which is measured when necessary.

Prior to the commencement of blasting operations and after their completion, Finnrock Oy will conduct a building review for the properties in the nearby area and damping of vibration-sensitive devices. The properties concerned will be contacted separately.

During the entire blast operation, Kalliotekniikka Engineers Oy will perform excavation vibration monitoring measurements in the nearest properties with continuously operating vibration gauges. The permitted vibration limits are based on the regulations in the blasting and mining industry that have been drawn up by the Ministry of Labor.

The progress of the excavation and any possible changes in the blasting will be carried out on the basis of the obtained measurement results so that no damage can occur. All excavation work is done in accordance with safety regulations and official regulatory guides.

Contact details of the main contractor for residents if required:

  • project manager Mikko Piirainen, 044 551 55 31
  • responsible site manager Juha Selin, 040 570 86 24
  • blasting expert Tapio Nummela, 040 066 21 01
  • site engineer Matti Westerlund, 050 439 61 43

email address format: first name.last name(at)kalliorakennus.com

Finnoo II excavation works

The main contractor for Finnoo's share of the construction and excavation of the wastewater treatment plant's inlet and outlet tunnels is the TYL FMS consortium of SRV Infra Oy and Pohjolan Kalliotyö Oy. 

Finnoo's share of the project is 3.7 kilometers. The tunnels are built deep inside the rock and are typically about 4.5 meters wide and 5.5 meters high. The new outlet tunnel will be connected to the existing sea outlet tunnel of the Suomenoja treatment plant, which leads the waters 7.5 kilometers south of Gåsgrund to a depth of 15 meters in open sea. The contract includes not only the excavation and reinforcement work of rock spaces, but also a considerable amount of building technology works in Suomenoja's current treatment plant area. The contractor will work as the main contractor also in the improvement works of the location concerned.  

The works of the Finnoo II project will take place between 2/2018 and 6/2021. Excavations progress in several tunnel drifts a few meters every blast. There are many limitations to excavation and the drifts progress at different speeds. Most of the excavations will be completed by summer 2020.

Working hours

Aboveground work which causes noise: 
  • weekdays 7am-6pm, if necessary 6pm-9pm (after 6pm less than 35dB)
  • Saturdays 9am-6pm (less than 35 dB) 
Underground work which causes noise: 
  • weekdays 7am-6pm, if necessary 6pm-10pm (after 6pm less than 35dB) 
  • weekends and public holidays from 9am to 10pm (under 35dB) 
  • if necessary, on weekdays 10pm-7am or on weekends and public holidays  10pm-9am (less than 30dB)
Tunnel blasting work: 
  • weekdays from Monday to Friday from 7am to 10pm 
  • Saturdays from 9am to 6pm
Underground loading and transportation of blasted rock from tunnel: 
  • weekdays 7am-10pm, weekends and public holidays from 9am to 10pm
  • if necessary, weekdays from Monday to Friday 10pm-7am
  • if necessary, on weekends and public holidays at 10pm-9am
The specific dB level refers to the noise level of the interior of a residential building, which is measured as needed.
 
Before the start of blasting operations and after they have been completed, Kalliotekniikka Consulting Engineers Oy will carry out building inspection and vibration-sensitive equipment damping on properties located within the potential impact area of excavation. Buildings will be reviewed before excavation is less than 150 meters from the property. The properties concerned will be contacted separately. Throughout the blasting work, Kalliotekniikka Consulting Engineers Oy takes measurements of excavation vibrations in the nearest properties with continuously operating vibration gauges.
 
Permissible vibration limits are based on legislation for the blasting and quarrying industry drawn up by the Ministry of Labor. The process of excavation and possible changes in detonations are made on the basis of the measurement results obtained so that no damage can occur. All mining operations are carried out in accordance with safety regulations and regulatory guidelines. We apologize for any disturbances this may cause.
 
Main contractor contact information for residents: TYL FMS, tel. 040 631 8700, finnoo2(a)srv.fi