Stockholm's future sewage treatment consists of a new sewage tunnel from Bromma as well as the Henriksdal treatment plant and the facility in Sickla under Hammarbybacken. Changes are made to both facilities and all remodeling and extension work is carried out while the treatment plant is in operation.

 

The sickle plant is embedded in the rock below Hammarbybacken. The facility is to be built. 530,000m³ of solid rock is to be drilled and blasted out for a facility that will accommodate rough cleaning, sand capture and pre-sedimentation. The facility will be four times as large as it was from the start. The expansion takes place for the most part below ground level in the mountain and will be located on two levels. These levels are connected by shafts and tunnels.

 

Nitro Consult's role and tasks in the project have been: blasting technical advice for blasting work in an existing facility under various conditions to maintain target values for vibration-sensitive equipment, assessment and consultation of slope stability for vibrations, carrying out supplementary risk analyzes and establishing target values, carrying out pre- and post-inspections of properties and facilities, prepare reports and accounts of work performed, damage inspections, third-party handling, carry out noise and vibration measurements and analyze results from these.

 

Before the blasting work began, Nitro Consult helped to develop guidelines for Hammarbybacken as the stability of the slope was uncertain because the foundation was not known and consisted mostly of fill masses. Inspections of properties and existing facilities as well as the installation of noise and vibration meters were done in good time before the work started in order to get a good amount of background data.

 

During the project, evaluations have been made in NCVIB of the distance-corrected measurement values so that the project can continue without downtime. Analyzes and forecasts of structural sound levels have been carried out to ensure that guidelines are maintained so that blasting and drilling work can be carried out in the evening until 10pm.