The article presents the experience of monitoring and taking protective actions aimed to ensure safety of the 1.5 – 4.5m diam. tunnel collectors at the depth of 7-70m, located in the zone affected by geotechnical influence of the underground and high-rise construction. Described is the philosophy of building the space-time structure of the geomonitoring. A comparative analysis of calculated-experimental data and the results of the many-year monitoring aimed to ensure safety of the underground wastewater collection and treatment facilities in St. Petersburg is given.