Building the Barkarby access tunnel from Robothöjden to Landningsbanan

This work consisted mainly of sheet piling, soil and rock excavation, rock shaft, rock reinforcement/sealing by grouting in tunnels, rock cutting and vertical shaft. The tunnels provide access to the following main tunnel contractor and as a service tunnel after the project is completed.

Earthworks, water, and sewerage work were included as well as concrete work for the superstructure for the vertical shaft, which includes a shaft for air supply in the future. Fences and gates were set up around the work areas. Some temporary installations were included that have been left behind for following contracts, such as ventilation, electricity and water/sewerage.

The backbone of the environmental protection work in the project was an environmental permit which regulated all the critical activities that affected the surrounding environment during the works.

The contractor put together a project-specific sustainability management plan that detailed the strategies and plans for all aspects of sustainability. The plan consisted of an introduction, purpose and application, information about the project, management of sustainability aspects, risks and opportunities, report and follow up, communications and effects on third parties.

In the management of sustainability aspects chapter, each aspect was described, had a goal, listed measures to reach the goal and how to follow up and report them and who was responsible for each part.

Land use and landscape

In the project, existing hard surfaces (such as the airfield) were reused when possible. Contaminated masses were handled according to the permit as described in the projects mass management plan.

In the project, storm water, process water and water which leaked into the existing tunnel in Robothöjden and the new tunnels had to be handled. Contaminants such as residues from explosives, minerals from soil and rock in the form of suspended material, and oil leaks from existing contaminants of PAH in asphalt or PFOS from previous military activity in the area were found. Treated water was led to spillage, recipient or was infiltrated on site.

During production, the treatment system was gradually expanded, both in terms of capacity to handle water volume, but also in terms of the type of pollution, in order to meet current guideline values. To lower the pH, Linde Gas was contacted, who assisted with support and equipment regarding pH regulation. Together with Envytech Solutions AB, the treatment systems were evaluated and expanded to meet the treatment requirements.

For example, PFOS was detected in leaking tunnel water, which was treated by supplementing with a buffer tank, two lamella containers, two bag filters, one sand filter, and two filters with activated carbon. Other parameters that needed to be handled were elevated suspended content and hexavalent chromium. For purification of hexavalent chromium, tests were carried out by client together with the Swedish Transport Administration.

Outgoing water from the runway contained too high levels of suspended material, so flocculants were added to reduce the amount of fine particles in outgoing drainage water. An alternative was centrifugation, but due to a great need for supervision and long delivery times, was rejected. Different flocculants were also evaluated, and the least pH sensitive agent was selected.

Transport

The sustainability plan contains an assessment of possible transport alternatives to the project including boat, train and plane. The products purchased for the project were transported differently depending on where they came from, and boats or trains are most likely used for parts of the route during long transports of heavy material (eg sheet piling). The last part of the transport to the project, however, took place by truck because there was no other possible way to reach the project site.

The procurement requirements described which modes of transport were procured for the project. Information about how to best travel to and from the project site was shared with the workforce.

People and communities

During construction stage there were several ways for the community to leave comments, such as through customer service, mailbox, open houses (some postponed due to covid), and information stands at municipality days/markets.

Every year there was an attitude survey conducted and newsletters sent out. Before each blast, text messages were sent out and information video for kids were produced and shared. There is also a separate project website, a Facebook page and LinkedIn.

Through the legal process there was also an environmental permit that regulated how aspects that can affect nearby residents must be managed and controlled, such as noise and vibration and water management.

The water environment

A control program is in place according to the environmental permit. Drainage water is checked and measured continuously, and an extensive water treatment plant was put in place.

To prevent any oil spills from reaching watercourses, filling stations have been built with embankments, only double-jacketed tanks were allowed within the workplace area, and absorbents must be present in all machines. During environmental and protection rounds, it is checked that everything is in order. Any deviations are handled in the project portal where measures and the person responsible for the measure are reported.

Collected stormwater and drainage water was reused for watering blasts in the tunnel.

Leaking groundwater from Landningsbanan was collected, treated and diverted to equalisation reservoirs to maintain groundwater levels and the water level in Igelbäcken, but it was never needed during the contract.

Physical resource use and management

Early in the project a workshop was held. The workshop evaluated:

• Water efficiency

• Energy efficiency

• Resources

• Waste

• Climate impact

The identified measures were listed in a resource plan where they were followed up.

Climate impact was calculated quarterly and project specific EPDs for asphalt, reinforcement, construction cement, concrete and sheet piling were used. The climate impact was reduced by about 1400 tonnes of CO2-eq compared to the impact estimated in the design stage.

Two big changes made were the change to HVO fuel and use of recycled sheet piling.

Energy from renewable sources was used in the project and parts of the fuel are from renewable sources with lower carbon dioxide emissions (HVO).

Suppliers are assessed regarding social sustainability (how large amount will be used, whether the material contains risk material and whether the material comes from a risk country).

A locally placed crushing plant was put in place (agreement between client and municipality). This has been used for excavated masses and to buy back bulk fill.

Leftover facility-specific material such as cement, bolt, beams, drive plates, lighters, cables, etc. are to be reused in future projects. In Frövi there is a warehouse for excess material. For example, black bolt has been delivered from the Norvik project to Barkarby, cables have been picked up from Frövi and sheet piling have been picked up from Veddesta.

The BREEAM Infrastructure process led to more discussions in the project group about sustainability. This in turn led to a better understanding and higher knowledge within the project.

Challenges

Both management of water to meet the requirements in the environmental permit (PFOS, chrome, particles) and reuse of water proved tricky, due to a lot of suspended particles and pH. This was managed by putting a local water treatment plant in place to treat the different contaminants and continuously test the water quality.

The project stored the soil masses on site hoping it could be reused in a project nearby, but due to time plan in the two projects it wasn’t possible to keep the masses for the time needed. So the masses had to be sent to a soil treatment plant 30km away instead of 3km.

Outcomes

Using BREEAM Infrastructure providedmethod to do the right things, measured on an international level. The framework provided a concrete way of showing environmental works.The certification provided financial benefits as the client had a bonus related to BREEAM Infrastructure that gave financial returns.

The client’s main driver was to use BREEAM Infrastructure as a tool to constantly improve the environmental and sustainability performance of their work and to increase their sustainability standard between each contract.