In work the influence of the buried bogs on negative transformations spreading grounds and occurrence of some exogenous processes, including biochemical phenomena. Such processes in many respects define safety of development and use of underground space of city. The special attention is inverted on marsh microflora, its number and variety of physiological groups, and also gross weight bacterial of weight. Under the certain hydrodynamical conditions marsh microbiota migrate downwards on a particles of rock. The sharp increase bacterial of weight in grounds under the buried bogs is marked in comparison with not waterlogged by sites. Is emphasized, that especially negative influence is rendered by the buried bogs on sandy adjourment, which frequently are transformed in are floating earth.