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We learn from controls

During the construction of the West Link, we will be conducting controls of our environmental impact. But we are already measuring factors such as noise, vibration and groundwater levels in order to obtain a picture of current levels.

- We are measuring before construction begins in order to obtain data with which to compare measurements made during construction. This will allow us to see what deviates from the norm, says Mira Andersson Ovuka, environmental supervisor at the West Link Project and PhD in physical geography.

Through measurement and through investigation of the current situation, we can calculate, analyse and assess how to undertake construction in a safe manner. We obtain knowledge and a picture of the current situation that we can use for comparison both during and after construction. 

- During construction, we perform more checks, some as a means of following up the current checks and providing a comparison, and some as a matter of new construction-related checks. For example, we perform measurements to see whether we are making the water cloudy when moving earth in watercourses and vibrations when we blast, Mira continues.

There are requirements imposed on our construction project by our environmental impact assessment, various laws and the Land and Environment Court. To comply with these requirements, we draw up a control programme in consultation with the County Administrative Board and the City of Gothenburg, who act as supervisory authorities.

- We have submitted out control programme to the Land and Environment Court. In autumn, the terms for our construction project will be confirmed and we will be able to say exactly which controls will take place, where and how often they will be and what guideline and limit values apply, concludes Mira.

The control programme is an indication of how we are to monitor and guide our construction project so as to minimise the impact on the environment. The control programme encompasses groundwater, dewatering (pumping water out of shafts and rock tunnels) and surface water, noise, vibration and air quality.

Ongoing controls in advance of the construction of the West Link  

The groundwater level is measured each month at around 600 locations via groundwater pipes, ground source heating wells and rock boreholes. The first measurement pipes were placed as early as 2012 and the number is gradually increasing up to the start of construction. An inventory and inspection of groundwater-dependent buildings and energy installations has been conducted within the area of influence for groundwater. We are also measuring sensitive objects such as buildings, ancient monuments and nature and green cultural environments.

Pore pressure measurements are conducted every other month. They are conducted in areas with clay. Pore pressure is a measurement of the stability of the ground. 

Bellows measurement is conducted in clay every other month and measures subsidence. 

Background noise has been measured on two occasions in the past year at twenty different locations in the city in order to obtain values to use for comparison during the construction phase.

Air quality is also being measured in several places in the city in order to have values to use for comparison during the construction phase.

Soil samples have been taken along the entire stretch. A classification has been made on the basis of how polluted the soil and clay is. Contracted recipients are ready for some of the spoil we will be digging up. 

Initial surveys have been conducted of all properties within 150 metres of the West Link route, as well as of buildings with sensitive foundations. Walls, roofs, any patterns of cracks and cellars have been documented in order paint a picture of the current state of these buildings. A survey is conducted in advance of the start of construction.

Vibration values, a maximum value has been set for all properties within 150 metres of the West Link route, as well as of buildings with sensitive foundations. This has been set on the basis of the building’s condition, its foundations and its cultural historical value. 

Subsidence is measured using subsidence studs that are mounted in selected properties in order to check any height movements in buildings and facilities, the aim being to ensure that there is no damaging subsidence. We are currently measuring about 2000 studs and are mounting more. Subsidence is also measured via radar satellite for buildings, land and other reflective objects such as well covers, kerbstones, railings or posts. We are measuring twice per year prior to the start of construction.

Water quality has been measured four times per year since 2015 at a number of selected locations in the rivers Säveån, Mölndalsån and Göta Älv.

Metals in moss have been checked every other year since 2014 in the rivers Säveån, Gullbergsån and Möldalsån and the canals Stora hamnkanalen and Rosenlundskanalen.

Mussels: their incidence has been checked every other year since 2014 in the rivers Säveån, Gullbergsån and Möldalsån and the canals Stora hamnkanalen and Rosenlundskanalen.

Water plants, their incidence and any impact has been checked every other year since 2014 in the rivers Säveån, Gullbergsån and Möldalsån and the canals Stora hamnkanalen and Rosenlundskanalen.

Bottom fauna, their incidence and any impact has been checked every other year since 2014 in the rivers Säveån, Gullbergsån and Möldalsån and the canals Stora hamnkanalen and Rosenlundskanalen.

Electrofishing in running water has been conducted every other year since 2014 in the rivers Säveån and Mölndalsån

Electrofishing from boats has been conducted every other year since 2015 in the rivers Säveån, Gullbergsån and Möldalsån and the canals Stora hamnkanalen and Rosenlundskanalen.

Endangered species have been checked every other year since 2015 in the rivers Säveån and Mölndalsån