One of Citytunneln’s objectives is for the finished connection to contribute to an environmentally-harmonised transport system and a long-term sustainable society. This will be achieved primarily by giving a greater number of people the opportunity to use public transport instead of using cars.
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A well for lowering of the ground water. |
Water is pumped up from the ground via extraction wells near the work area and pumped back via infiltration wells some distance away. |
The surroundings and the environment have been affected during the construction period in a number of ways. The Citytunnel project has been tested under the Environmental Code, legislation on the building of railways, and planning and building legislation. A new Environmental Code was passed in Sweden in 1999 which, in many respects, is much stricter environmental legislation than previously.
Fundamental environmental tests
The consequences of the construction and operation have been tested in the Environmental Court, partly through compulsory testing of lowering the ground water and building in water, and partly through voluntary testing of environmentally-hazardous activities. Citytunneln is the first major infra structure project that has been fully tested according to the Environmental Code, which makes it unique in an environmental context.
Citytunneln’s application to the Environmental Court was submitted on March 1 2002. In August 2004, the Environmental Court carried out negotiation for the part of the Citytunnel Line with linking tracks in Hyllie/Vintrie including both water and environmentally hazardous activities. The judgement on this was delivered in December 2004. The judgement covering around 220 pages establishes in detail the environmental conditions that apply to the project in both the construction and operating stages. Negotiations on the other section, the linking tracks in Lockarp, were held in January 2005 and judgement was delivered in November the same year.
Environmental testing has meant that the Environmental Court has set detailed conditions for, e.g., the amount of noise and vibrations to which those who live near workplaces may be subjected to during the construction period. The Court has also detailed the maximum amount of groundwater that may be pumped away from the construction workplaces, and what proportion has to be re-injected. The decisions of the Environmental Court have, in turn, formed the basis for agreements with contractors. Among other things, this has had consequences for the choice of working methods, the materials and chemical products to be used, and the permissible content of foreign substances in waste water.
Groundwater and pumping
The work on Citytunneln means that the water level must be temporarily lowered along parts of the stretch, and primarily at Malmö C, Triangeln Station, Holma and Hyllie/Vintrie, and also at Lockarp.
Extensive pilot studies, test bores, and pumping trials have been carried out to assess the properties of the limestone, and the groundwater flows. A geohydrological model has been set up on the basis of these results. This has been done in accordance with obligatory testing as defined in Section 11 of the Environmental Code. Lowering the water level has been limited to affected areas as defined in the two environmental judgements, where buildings, watercourses, surface water and plant life could be affected.
To limit the extent of the affected areas as much as possible, water is pumped back into the groundwater reservoir. The Environmental Court defined a minimum proportion that had to be re-injected in order to take account of groundwater as a resource, and this was later included in the government’s decision on permissibility. Water is pumped out of the ground via extraction wells near the work area and re-injected via infiltration wells some distance away in order to maintain groundwater levels in the area around the workplaces.
Groundwater levels are monitored via a number of measurement points. In central Malmö there are buildings on foundations that cannot tolerate a lowering of the water level, which is another reason why it is monitored continuously. South of the tunnel mouth, permanent lowering is needed in certain sections to retain the stability of the tunnel. The consequences are limited as much as possible through water being re-injected.
In general, trees in central Malmö are not affected because the soil layer forms a seal, and lowering takes place in the underlying limestone. On the other hand it has been necessary to remove some trees in places where the open cutting was excavated. In the vicinity of cuttings at Triangeln, supplementary watering of trees was carried out during summers.
The extent of watering has been decided by Malmö City on behalf of Citytunneln. An important lesson learnt from protecting trees in areas where groundwater has been lowered is the need for supplementary watering even during rainy summers. An example was the need for supplementary watering of the trees beside St Johanneskyrkan during the summer of 2007.
Since the tunnels have been clad with lining at the same rate as the tunnel-boring machines moved forward underground, the tunnel boring did not mean that the water table had to be lowered, nor will future operations affect the water table.
Building noise, vibrations and atmospheric pollution
Noise and vibration has caused most disturbances during the construction period. Structure-borne noise, i.e. sound propagated through the rock up into buildings above ground, was also disturbing. Air pollution was caused mainly by machines transporting materials and excavated spoil. The Environmental Court determined levels for both noise and air pollution. The main noise nuisance during the construction period was from excavation of construction pits, construction of support walls, and transport.
During the construction phase, housing, schools and other activities experienced noticeable vibration levels. Construction noise and vibrations were limited primarily by the choice of working methods. Where support walls were constructed in excavated areas of the site, noise and vibration was considerably reduced by the choice of one building method in preference to another. A number of machines were electrically-driven to reduce air pollution levels. Other machines were equipped with special diesel engines and cleaning equipment.
As the tunnel-boring machines advanced underneath Malmö, some buildings above were subjected to noticeable structure-borne sound. Residents were given extensive information regarding the boring work, and some was offered hotel rooms.
Measures will be implemented to reduce the structure-borne sound generated by rail traffic in the tunnels during the operating stage. Calculation models used to forecast structure-borne noise in the operating stage have also been calibrated in the construction stage. Screens and embankments have been erected to reduce airborne noise. With this protection in place, noise from rail traffic during the operating stage will be within the Swedish National Rail Administration’s and the National Environmental Protection Board’s guidelines for good environmental quality. Read more about Railway installations and the damped track system.
Waste water
Waste water from the building sites can contain earth and limestone particles. There may also be low levels of oil from engines, shuttering releasing oil, plus concrete residues, surfactants, and polymers from tunnel boring, as well as injection material residues. Water management involves a number of measures, including oil separation, pH adjustment, flocculation, and sedimentation.
The innermost part of Inre hamnen at Skeppsbron has been converted into a sedimentation basin where waste water is cleared of concrete dust and other pollutants before being released into the Öresund. Separation, using a geotextile screen, is an important measure for compliance with the conditions for release into the sea. The various purification measures and flow equalisation bring down concentrations to such an extent that the waste water can be released into the Öresund without negative environmental impact.
The activities of the Citytunnel project are established according to the requirements of ISO 9001 (quality management systems) and ISO 14001 (environment management systems).
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Clean excavation mass from the building of Malmö C and Triangeln station plus boring mass were transported to Norra hamnen as infill.
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To avoid trucks contaminating the streets, each workplace was equipped with automatic washing sites which flushed the trucks’ wheels and undersides clean. |
Solid Waste and excavation spoil
Solid wastes occur as conventional building waste, demolition waste, and domestic waste from staff facilities. Only a small proportion of the construction and demolition waste requires special treatment. Oil waste and chemical residues are treated as hazardous waste. Waste from site huts, etc., is treated as domestic waste.
Clean excavation spoil from the project plus boring mass are taken to the Norra hamnen for use as infill. Excavated waste therefore contributes to the continued development of the harbour. To avoid trucks contaminating the streets, each workplace is equipped with automatic washing plant where the wheels and underbodies of the trucks are flushed clean.
Excavation spoil from the construction of Hyllie Station, the connecting tracks south of Annetorpsvägen, and the Lockarp area that is not used for noise embankments is used primarily for landscaping. The rest is taken to Norra hamnen. Excavation spoil (mainly from Malmö C) which is suspected of being contaminated is transported to SYSAV for treatment.
Chemical products
All chemical products used are checked carefully. Checking is done by referring to safety data sheets and via an analysis of the physical and chemical properties of the products. An environmental risk analysis is also carried out for products that may come into contact with earth or water. This is based on handling, working methods, quantities used, and methods of use.
The various contractors shall approve chemical products on the basis of established requirements. Then, applications are sent to the Citytunnel project for review. The procedure also includes checks and decisions on products by the Swedish National Rail Administration. In accordance with the environment decisions of the project, information on chemical products is issued to the supervising authorities. In total, almost 2,000 applications have been submitted by the various contractors to the project.