The Mankkaa municipal waste landfill operated in 1957–1986. The surface area of the landfill was 48 hectares at most. The volume of the landfill was around 2.5 million cubic meters and the total mass around 1.8 million tons, of which around 1.2 million tons was municipal waste and 0.6 million tons cover soil.
The planning for the landfill restoration began in 2000, and the planning for the construction of a golf course and a public recreational area started at the same time with good cooperation between the parties. The following factors were crucial for the success of the project: planning steering, contractor’s participation already at the preparation phase, and local supervision and continuous observation at the worksite.
Sito was responsible for the following project tasks:
- Independent quality control during the planning phase. The task included, for example, implementation inspections of plans and project areas.
- Independent quality control during project implementation which consisted of, for example, preparing a project-specific plan for quality control (subproject-specifically), performing quality control (plans and quality requirement inspections), worksite meetings and reviews, and worksite supervision.
- The tasks of a person who was responsible for the environment including, for example, the coordination of the project progress according to permit conditions and having the necessary plans and reports approved by authorities, a final review, worksite supervision, and preparing annual reports, subproject reports and final reports.
The actual restoration project of the municipal waste landfill began in 2009 and was completed in 2012. A nine-hole golf course was opened in 2012 , and this was fully completed in 2013.
The restoration included refilling, cutting and shaping required by the closing of the landfill, the construction of collection drainpipes of landfill waters, the construction of a surrounding part and a vertical insulation wall, and the construction of surface structures of the landfill and a gas collection system.
Improvements on infrastructure and municipal engineering that were carried out in connection with the restoration are included as part of a more extensive development work performed by the city of Espoo in the surrounding areas. Following the local zoning, the project included a bridge and passages for pedestrians and cyclists, an outdoor path, and improving Turveradantie as part of the ongoing more extensive development of the Mankkaa region. In order to make the drainage of the external water of the landfill more efficient, sewer lines were constructed and repaired and new culverts were installed. At the same time, the recreational use of the area was increased, and a basis for further construction of surrounding areas was created.
The environmental effect of the restoration consists of the effective recovery of harmful gas and reusing it as energy. The reduction of carbon dioxide emissions is estimated to correspond to the amount produced by 20,000 cars/year.
The costs of the restoration of the landfill including all projects and contract areas were around 17.5 M€.
– This has been a very successful project from many perspectives. The project has been able to take care of an environmental problem caused by the landfill. At the same time, the problem that has prevented the use of the surrounding land area has been resolved, and the area is now an attractive oasis. The project has also been a good example of cooperation between a public and a private operator, says Harri Tanska, City Engineer of the city of Espoo.