Oxidation Blamed for Stains on New St. Petersburg Metro Stations

Passengers noticed rusty streaks in the passage between the Kirovsky Zavod and Putilovskaya stations shortly after the opening of the first two stations of the Krasnoselsko-Kalininskaya line.

«These are not streaks or water seepage,» the press service told Fontanka. «Any rock contains iron, which when in contact with certain substances oxidizes. We observed the result of that reaction. This is a temporary phenomenon that is quickly eliminated with a special solution.» According to Metrostroy of the Northern Capital, the stains have already been removed.

Some observers also noted wet spots on the floors and walls of the new vestibules. It was suggested that the cause could be the use of granite with high water absorption and open porosity.

For the finishing of the Gorny Institut, Putilovskaya, and Yugo-Zapadnaya stations, materials such as Mansurovsky, Sibirsky, and Sinegorsky granite, as well as amphibolite, were used. In 2023, the Moscow State Institution for Capital Repair of Apartment Buildings UKRiS, in a special letter, did not recommend contractors to use Mansurovsky granite due to the possible appearance of rusty traces associated with high iron content.

Responding to questions about the choice of materials, the press service of Metrostroy of the Northern Capital stated: «As a contractor, we are guided by the architectural project. Regarding finishing materials, we take into account the recommendations of the designers.»

The first section of the new brown line from Yugo-Zapadnaya to Putilovskaya was opened at the end of 2025. Simultaneously, work continues in the St. Petersburg metro to rectify issues and eliminate water seepage in other sections of the network:

• Nevsko-Vasileostrovskaya line from Primorskaya to Begovaya;
• Frunzensky radius from Sadovaya to Mezhdunarodnaya and further to Shushary.

The work is scheduled to be completed by the end of this year.