| English term or phrase: sanitation systems vs sewerage systems | Коллеги, помогите разобраться, что имели авторы в виду под sanitation systems. Так как в тексте 2 пункта подряд. sanitation systems и sewerage systems. Как для меня, и то, и другое - канализационные системы. В чем отличие? Есть ли у Вас версии? (это тендерная документация)
b) Coverage of Sanitation Systems:
Consultant will study carefully the urban development plans and related sewerage master plan projections, in particular:
• The Housing and Utilities Amenities Committee manages a total of 26.8 km of sewerage mains, 5 sewerage pumping stations, and 2 wastewater treatment facilities within two sewerage catchments and systems (west and east) serving 72.4% of residential areas. In terms of development of the town sewerage system, several primary actions have been planned under current Stage I, such as repair and reconstruction of the existing Dekhnovka WWTP; the reconstruction of sewerage pumping station-2; the restoration of the third pressure pipeline (1.0 km) from sewerage pumping station-2 to the Kladochki WWTP; the relaying of emergency gravity flow sewerage mains in the area of the northern industrial zone and other streets (1.0 km); the construction of previously designed mains and sewerage pumping station in the settlement of Khmelevka; and the construction of 4 sewerage pumping stations, laying of 10.0 km of gravity flow collectors and 2 km of pressure pipelines in areas of new residential construction. At the 2nd stage, further development of the centralized sewerage system covering sewerage of whole town development and waste diversion from western part of the town into the Minsk sewerage system and from eastern part to the Dekhnovka WWTP. Works under this Task includes the installation of gravity flow collectors (14.0 km), five sewerage pumping stations and pressure pipelines (12.0 km). For new residential construction, it is intended to arrange gravity flow sewerage mains and build several sewerage pumping stations with waste waters disposal for treatment to any of the existing WWTP of Dekhnovka. For the other settlements using decentralized or local domestic sewerage systems
Municipal Unitary Enterprise of Housing and Public Utilities managed sewage network (95.8 km) and 30 pumping/lifting stations. A part from replacement (restoration) of the pressure pipelines feeding the WWTP, there is no provision in the TOR of any specific scope of works for upgrading the sewerage network. However the discharge wastewater from the current and future network extension will need to be considered for the reconstruction of the WWTP since the town is expected to grow rapidly (beyond 100,000 people). Currently the average daily wastewater load entering the WWTP is 28,000 m3.
c) Sewerage System
Consultant will evaluate precisely the current status of the sewerage systems in each of the 3 target towns and determine critical issues in the context of:
• Capacities and hydraulic loads: verification of sewer (gravity and pressure collectors) diameter based and velocity, based on hydraulic calculations of each catchment, made by the local Companies; verification of pump capacities (pump and lifting stations) as well as capacity of main sewer trunk (primary network) delivering wastewater to the WWTP; verification of drain field capacities and capacities of centralised WWTP as well as smaller (individual) plant facilities; verification of industrial plant capacities if any (or pre-treatment unit capacities).
• Age (service life), quality of materials and equipment (pipes, valves, pumps and etc.): Investigation/survey of sewer mains, collectors and pump stations: EPTISA will conduct random surveys, starting with the critical sections where sewer pipes are reported to be mostly affected by damages or high infiltration and exfiltration losses. The surveys shall give accurate information about the present situation, length and diameter of pipes and interconnections with stormwater in case of combined collectors. Deficient pump/lifting stations will be investigated and defects recorded (civil structure/sump, pump house, electrical and mechanical facilities, etc.). In collaboration with the Companies, EPTISA will detect, classify and rate the severity of defects of all main collectors (in particular sewer trunks feeding the WWTP) and pump/lifting stations.
• Classification of sewer pipe assets: One important aspect of the sewerage network audit will be to check for each catchment the detailed inventory of the sewer pipes as per their current topology, function and layout/configuration (e.g. separate or combined). Such inventory, which is needed at later stage for developing options in relation to the reconstruction or the key sewers and trunk mains. EPTISA intends to verify and update the register of all existing assets and sewer pipes and recommend a basic classification of existing and future sewerage network elements.
• Operational condition, reliability and suitability: After having verified the location of all assets (pipes and pump/lifting stations) through verified maps/site inspections and classified all sewerage system assets, EPTISA will carry out specific investigations and assessments on sewer pipes (in particular trunk mains) to assess further their condition and current lifetime, so as to provide information for future sewer rehabilitation and priorities for replacement of collectors/sewer trunks. The data will also be used for establishing some parameters for the hydraulic calculations (e.g. roughness coefficients, etc.). We will complete the diagnosis by an assessment of the deterioration and failure of pipe assets (with a focus on larger diameter sewer trunks) and manholes/interceptors. To cover the whole sewerage network targeted for reconstruction in each town, pipe diagnosis and rehabilitation planning will have to be focus on sample groups of pipes and not on individual assets as this will be very time consuming. However, since the efficiency of rehabilitation planning depends on the quality and quantity of available data, it is essential that information on pipe material, size, age, type of bedding, soil characteristics, operating pressures, time, place and type of historical breaks are collected and analysed. It is likely that only partial sets of data on pipe material and condition exist at local level with the operating Companies
• Power efficiency (e.g. pumping or lifting stations): number of pump inventory, diagnostic, field pumping tests and analysis of pump curves of the respective pumping/lifting station will be performed. This included physical data and description of each lift station and pump station, their current status of operations and problems, troubleshooting procedures, review and preliminary analysis of manufacturers` and current pump curves as well as review of existing maintenance logs and initial field pumping test results.
• General estimate of quantity of infiltration (from stormwater or cross-connections): Consultant will review the estimates of dry weather flow for each catchment/system in each town (e.g. flow that occurs in sewers in separate sewerage system or the flow that occurs during dry seasons in combined system). These flow estimates are required for each sewer trunk to be upgraded or new ones to be extended to the current sewerage systems, as they indicates the flow of sanitary sewage. This flow depends upon the rate of water supply, type of area served, economic conditions of the users, weather conditions and infiltration of groundwater in the sewers, etc. Correct estimation of sewage discharge is necessary; otherwise sewers may prove inadequate resulting in overflow or may prove too large in diameter, which may make the system uneconomical and hydraulically inefficient. Hence, before designing the sewerage system it is important to know the discharge / quantity of the sewage, which will flow in it after completion of the project and at the end of design period (2046). Apart from accounted water supplied by local Water Companies that will be converted to wastewater, EPTISA will estimate for each catchment/main sewers targeted by reconstruction the additional flow due to infiltration, e.g. quantity of groundwater seepage into sewers through faulty joints or cracks formed in the pipes. The quantity of the water depends upon the height of the water table above the sewer invert level. If water table is well below the sewer invert level, the infiltration can occur only after rain when water is moving down through soil. Quantity of the water entering in sewers depends upon the permeability of the ground soil and it is very difficult to estimate. EPTISA will review the estimates of infiltration and exfiltration (e.g. from leaking manholes into the soil) used by the Master plan or recent pre-studies. |
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