Home to more than five million people, the city of St. Petersburg, Russia has traditionally been one of the Baltic region’s greatest sources of pollution. However, by reducing the amount of untreated wastewater being released into the Baltic Sea by 50 per cent, the city’s new Southwest Wastewater Treatment Plant will significantly improve the region’s environmental health.
The result of a large-scale cooperative effort between Russia, Finland and Sweden, the Southwest Wastewater Treatment Plant processes about 330,000 cubic meters (432,000 cubic yards) of wastewater daily from the homes of 700,000 southwest St. Petersburg residents. The plant will dramatically reduce the amount of suspended solids, phosphorous, nitrogen and organics being discharged into the Baltic Sea. A 40% to 60% reduction in heavy metal salts is also expected.
The city's new Southwest Wastewater Treatment Plant will significantly improve the region's environmental health.
With any wastewater treatment plant, concrete waterproofing is a major concern, since the migration of water or contaminants in or out of concrete cracks can affect the facility’s operations as well as the surrounding environment. The St. Petersburg plant’s project team was especially concerned about waterproofing the concrete tunnels that supplied water to the facility’s tanks.
Although the project contractor and engineers had considered using externally applied waterproofing membrane systems, they knew these systems eventually deteriorate, requiring expensive repairs and maintenance. Having ruled out external membranes, the project team was seeking a concrete waterproofing system that would be quick and easy to install, and, more importantly, would last the lifetime of the structure.
In researching waterproofing alternatives, the St. Petersburg plant team considered Kryton International’s Krystol Internal Membrane High Strength (KIM HS). KIM HS uses Kryton’s proprietary crystalline technology to transform concrete into a watertight barrier.
When added to a concrete mix, Krystol reacts with water and unhydrated concrete, causing millions of needle-like crystals to form, blocking the penetration of water and corrosive elements and resisting hydrostatic pressure. Over time, incoming water causes additional crystals to form, self-sealing small concrete cracks and reducing repair and maintenance time and costs.
At first, the team worried that promises of KIM HS’s easy installation, permanent waterproofing and self-sealing abilities might be too good to be true. However, after viewing test results from the Swedish Cement and Concrete Research Institute and learning that KIM HS had received an Agrément Certificate from the British Board of Agrément, they were convinced that this innovative product would perform as promised.
Approximately 2,000 kg (4,400 lb) of KIM-HS was used in the St. Petersburg Southwest Wastewater Treatment Plan. Three hundred cubic metres of KIM HS-treated shotcrete was applied to a thickness of 8-10 cm (3.1 to 3.9 in) on the tunnel walls.
The wastewater plant was completed – under budget – in September 2005. Swedish Prime Minister Goran Persson, Russian President Vladimir Putin and Finnish President Tarja Halonen participated in the inauguration of the plant, which Finland’s Environmental Minister, Jan Erik Enestam, called “one of the most significant environmental projects in the Baltic region in recent years.”
The project contractors, NCC, Skanska and YIT, were highly pleased with the performance of KIM HS in the construction of the plant’s water tunnels and as a result, will likely use it in future projects in the region.
Benefits of the St. Petersburg Southwest Wastewater Treatment Plant should be visible as early as mid-2006. The reduction in the release of wastewater into the Baltic Sea will improve the condition of local waterways and beaches and, in the long term, the Gulf of Finland and the Baltic Sea as a whole.