New Helsinki was created organically: preconstruction implemented at Koirasaari and Stansvikinranta in 2019–2020 increased the surface area of the district by 6.7 hectares. The preconstruction contract was the first phase of an extensive City of Helsinki project in which a new residential district will be built in the Koirasaari area of Kruunuvuorenranta for a total of 13,000 residents.
Contaminated surface soils were first removed from the expansion area and then clays were dredged away down to the hard sea bottom. The environmental dredging consisted of a total of 5,000 m3, and the bottom dredging some 328,000 m3.
“The dredged area was filled with blasted rock, which was then deep compacted,” says Project Manager Juha Seppälä about the project, which began in April 2019. Around 900,000 m3 of blasted rock, supplied by the customer itself, was used in the project.
A swimming beach around 400 metres long – or more precisely its underwater section – was implemented at Stansvik at the same time. Clay was removed from the beach area and replaced with sand, of which around 70,000 m3 was brought to the area from Porvoo.
The contract progressed so well that it was handed over to the customer months in advance.
“The contract period ended in July 2020, but we delivered the site to the customer in February,” says Seppälä.
The aim is to be ambitious in implementing the new seaside residential area: canals, small boat berths, beach boulevards, diverse services, and outdoor and recreational opportunities, for example, have been planned for the area.
