The Environmental Centre of Uusimaa has approved the notification submitted by Länsimetro Oy regarding the temporary disturbance to be created by its activities at Ruoholahti. The period for such work has been defined by the centre as principally between the hours of 7 a.m. and 10 p.m. on weekdays (Monday to Friday).
Work at Ruoholahti referred to in the notification covers drilling into the rock as preparation for mounting the protection of the existing metro turnaround line, widening of the access tunnel mouth, and excavation work in connection with the access tunnel, rail tunnel and vertical shaft. The work phases that will generate noise are rock drilling, blasting and scaling (removal of loose boulders from the rock wall).
Excavation work above ground consisting of drilling, blasting and scaling may be carried out on weekdays from 7 a.m. to 6 p.m. If drilling or scaling is to be carried out between 6 p.m. and 10 p.m. the consequent noise level in residential buildings, hospitals and hotels must not exceed 40 dB. If blasting is to be carried out after 6 p.m., the timing of the blasts needs to be communicated to the parts of the area most affected by the noise and vibration.
Underground tunnel drilling and scaling may be carried out from 7 a.m. to 6 p.m. on weekdays. If work is to be carried out between 6 p.m. and 10 p.m. the consequent noise level in residential buildings, hospitals and hotels must not exceed 40 dB. Tunnel blasting may be performed between 7 a.m. and 10 p.m. on weekdays.
In order to preserve current metro traffic arrangements, drilling connected with mountings for protective structures may only be performed at night between midnight and 5 a.m. Diamond drilling or the equivalent will be used to maintain noise levels below the standard value of 30 dB for residential buildings, hospitals and hotels.
Rock mass excavated at Ruoholahti will be transported to Jätkäsaari along the route Salmisaarenkatu – Porkkalankatu – Laivapojankatu – Jätkäsaari. Blasted rock will not be transported along residential streets at night between 10 p.m. and 7 a.m.
The Environmental Centre of Uusimaa’s approval of the notification is based on the Government Decision concerning standard values for noise levels. The level of noise permitted can be compared to approximately 20 dB for the rustle of leaves, 40 dB for whispering, and 60 dB for the normal speaking voice.
The preliminary contract period for the Ruoholahti access and metro tunnels is scheduled for November 2009 to May 2011, to be updated once contractors have been selected. Details of construction work will be communicated to local residents and operators before the work begins, and at regular intervals throughout the construction period. Länsimetro Oy will carry out real-time monitoring of excavation vibration and progress, as well as noise, vibration and other environmental impacts arising from the work.
Further information:
Länsimetro Project Engineer Tero Palmu, tel. +358 46 877 432, tero.palmu@lansimetro.fi
Länsimetro CEO Matti Kokkinen, tel. +358 50 347 1558, matti.kokkinen@lansimetro.fi
Länsimetro
Länsimetro Oy is responsible for the technical implementation of the Ruoholahti-Matinkylä metro line, involving construction, ownership, maintenance and development of the tracks, tunnels, station structures and parking spaces serving traffic on the 13.9 kilometres of underground metro line, as well as other structures and equipment in support of its operation. The west metro will bring into existence seven new stations. Construction of the west metro is through a joint project involving the cities of Espoo and Helsinki. Länsimetro’s office is situated in Tapiola. www.lansimetro.fi
