In the concept of development of St.-Petersburg the important role plays the improvement of the general scheme of the water drain of city, including reconstruction of old and construction of new underground sewer collectors. Because of diversity and complexity of engineering-geological and hydro-geological conditions of St.-Petersburg the building of such underground constructions represents the certain difficulties. The brief review of a current condition of a sewer network of St.-Petersburg is given. Features of engineering-geological and hydro-geological conditions of construction of underground sewer collectors by microtonneling technique in different areas of city are shown. The basic provisions on studying conditions of construction and operation of the given constructions are formulated.
At present, gas-liquid cleaning agents are widely used in drilling exploration wells.
