Protection of the Imeretinskaia Lowland from surface runoff flooding

Summary

Short information on the engineering-construction solutions of removing surface runoff from a development area on the Imeretinskaia Lowland territory of the Krasnodar Area is presented. Its surface is slightly elevated above the sea level (from 0.7 to 4 m); therefore, pressure removal of 100% storm runoff which at times becomes a disaster (during heavy rains) and causes significant damage to the territory is required. Removing surface runoff from residential areas of the Olympic park also requires advanced treatment. Taking into account the construction conditions the entire territory has been divided into five drainage areas to reduce the depth of the collection network and engineering structures. In each area a complex including a pumping station, an accumulating tank and advanced treatment facilities has been designed and built. The surface area of the drainage sites significantly differs from each other (30–440 ha). Following the extended survey and substantiation of the pumping equipment choice angular flow pumps with capacities 5 and 12.1 m³/h and 12.5 m head were selected. Taking into account the partial removal of pollutants in the accumulating tank two-stage filtration was used for advanced surface runoff treatment. Wastewater is treated with «Aqua-Aurat™18») coagulant and processed in the filters of the first stage with quartz sand media. To provide for the complete removal of residual dissolved oil products wastewater is supplied to the rapid gravity sorption filters of the second stage with MIU-S2 activated carbon media. The accumulating tank is cleaned from sludge regularly 2–3 times a year using a bucket loader. Sludge generated in the process of chemical wastewater treatment is dewatered in a belt filterpress. Dewatered sludge is disposed to the solid waste landfill.

Key words

treatment facilities , surface runoff , drainage area , rainfall intensity , pumping station , angular flow pump

Specific features of estimating calculated rainfall rates with account

Summary

The analysis of official data resources shows that the distribution of extreme rainfall over the territory is carried out with account of the microclimatic features of the area. To estimate the degree of reliability of such patterns within megalopolises, experimental studies were carried out, where the wastewater disposal system of St. Petersburg was assumed as an experimental base; a network of 34 automatic rain gauges recording with an interval of 5 minutes was assumed as a measuring instrument, and a base was used as experimental information, i. e., a measurement data base for six years. As a result of the research, it has been established that a microclimate is formed in the urban environment that differs from the climate outside it. Besides, on a megacity scale, there are microclimatic zones where the dependences of precipitation intensities on their frequency can differ significantly. In this case, the differences begin to manifest at periods p of one-time excess of the calculated rainfall intensity from 1.5–2 years, whereas at lower values, no differences have been found. The result obtained is consistent with the research data obtained by other authors, who experimentally established that the amount of extreme rainfall increased in those areas of megacities, as a rule, historical ones, where fewer green spaces are located, and, accordingly, a higher degree of surface overheating in summer is recorded.

Key words

rainfall intensity , surface runoff disposal system , climatic parameters , rainfall duration , flooding , microclimate