Design of the sewage collectors
Sewage collector is the main channel of drainage system. It is a big diameter pipe. Collectors are the parts of city sewerage system; they collect the drainage and waste water and deliver it to the pump stations, waste water treatment plants or to the discharge points (canals, basins etc.). Sometimes the small rivers and canals that flow within the city are directed through collectors. Collectors mainly are constructed from large concrete and reinforced concrete blocks.
Collectors have a number of advantages as follows:
- Reduction or a complete elimination of digging the streets during construction and reconstruction of underground pipelines and service works on pipelines;
- The corrosion processes are not so strong in the general collectors in comparison with laying of pipelines and cables in soil;
- Possibility of placement of pipelines group in the collector occupying rather small place in the plan and a section of the street;
- Quick improvement of service conditions of the underground pipelines which are laid in the general collector due to possibility of regular supervision and acceptance of preventive measures without digging the streets;
Feasibility studies on construction viability of the general collectors include the comparative analysis of construction cost of pipelines’ laying in the general collector and simply in soil. We evaluate not only the cost of earthwork and collector construction but also the cost of underground pipelines as at their laying in soil or in a collector it is applied a various designs of pipelines. The cost of pipelines in a collector is lower because there is no need for a construction of a number of inspection chambers, there is no need for arrangement of channels for pipelines of heating systems, part of cable networks are arranged with applying of the lead cables instead of the armored.
Complexity of placement of gravity-flow pipelines in the general collectors doesn't exclude inclusion them in a collector under some conditions as follows: compliance of a longitudinal bias to requirements of the admission of estimated discharge, the acceptable dimensions of pipes, possibility of the branches etc. Gravity-flow pipelines’ inclusion in a collector is not excluded in foreign practice.
The general collectors are applied on the main city streets with considerable traffic and pedestrians. The general collectors furthermore are constructed during construction of tunnels and platforms on crossings of streets in different levels and on approaches to the bridges.