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May 10, 2012 (Image: Arrow Step 01) According to [EN14654-1:2005], the description of the drain and sewer system provides an essential base for:
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May 10, 2012 The review of the existing system data should include all available network data. (Table: Content of a sewer database adapted from DWA-M 145) The review of the existing system data should include all available network data. According to [DIN EN 14654-3], this includes: a) inventory data 1) type of wastewater (sewage, rainwater, mixed water or special wastewater); 2) properties of the sewer (shape, size, gradient, depth, material, etc.), presence and properties … |
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May 10, 2012 Example: The invert gradient of individual lines or line sections can be the first determining factor to the self-cleaning capability and the wall shear stress in a given area of the sewer system. (Image: Grouping of the sewer network sections) |
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May 11, 2012 Initial sections usually have a gradient of between 3 ‰ and 10 ‰, while sections in the middle network area have a gradient of between 2 ‰ and 3 ‰. In the last sections of the sewers with larger cross-sections (branch collectors, main collectors, etc.), the gradient is chosen to be between 1 ‰ and 2 ‰, or even lower in some cases, depending on the topographical conditions. The table on this page shows the main characteristics of the three sewer network … |
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May 16, 2012 In addition, the following aspects should be checked: Origin of the wastewater (residential areas, commercial areas, large plants, hospital etc.) Possible damage potential (i.e. consideration of equipment and buildings which requiring greater flood protection, for example) Local terrain (Backup heights vs. line elevations) (Image: Origin of the wastewater (residential areas, commercial areas, large plants, hospital etc.)) (Image: Possible damage potential (… |
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May 11, 2012 The analysis of the previous cleaning methods should additionally be based on interviews with the cleaning staff to document the "on-site knowledge". (Image: Exchange of information between planners and operational staff) |
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May 11, 2012 (Image: Arrow Step 02) "Planning is the conceptual anticipation of steps that seem necessary to achieve an objective. In the process, it is taken into consideration by which means the objective is to be achieved, how these means are to be applied and how the achieved results are to be controlled." [Wikipedia] |
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May 11, 2012 The quality of the plan is primarily defined by the extent to which the information relevant for planning is up to date. In this particular case, the most essential aspect is the acquisition of additional information regarding changes in the structural condition and deposit situation. For that reason, the planning and implementation of additional inspection measures are integral components of the cleaning plan. The development of a cleaning plan includes: |
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May 16, 2012 Inspection plans are developed based on the "review and description of the drain and sewer system" that has been realised in step 1. Their purpose is to determine the on-site situation regarding the formation of deposits and the need for planned cleaning measures. (Image: Visual inspection of a manhole from above - deposits) Visual inspection of a manhole from above (Image: Visual inspection of the manhole and line using a mirror) Visual inspection of … |
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May 16, 2012 The visual inspection of the manhole is used to determine the deposit amounts, and to assess the structural condition of the manhole including defective grates, access ladders, and trash traps. (Image: Inspection of a manhole) (Image: Visual inspection of a manhole) |
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May 16, 2012 The oldest and simplest way to get a general overview of the internal condition of a straight section of inaccessible sewer is to directly look inside of it with the help of a mirror and an additional light source. The mirror, held at a 45° at the opening of the pipe, allows for inspection to take place without the need for direct entry into the manhole by personnel. Additional lighting shun into the pipe section, either at the next manhole or directly … |
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May 16, 2012 The CCTV camera system consists of a video camera that is attached to the end of a telescopic rod which also has a lamp used for the illumination of the section to be inspected. The telescopic rod can be extended up to a length of 12 m. Through the use its optical zoom and additional lighting, the camera is capable of identifying problems (such as blockages, roots and debris etc.) up to 30 m beyond that of a regular visual inspection.
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May 16, 2012 Sewer measuring boat The sewer measuring boat can be used in sewers from DN 700 to DN 2000. It floats on the wastewater and uses sensors to measure the height of the wastewater and the settled deposits in the pipe. The stored sensor data is later processed to obtain a precise determination of the deposit situation within the sewer line. However tough, the sensors do need to be manually re adjusted when the size and shape of the pipe changes. The … |
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May 16, 2012 Culvert pressure unit A special development in the measurement of deposit amounts is the culvert pressure unit. The device uses two pressure sensors connected to an electronic data acquisition system to collect pressure data at two points within the pipe. The data storage unit is located in a watertight plastic capsule that is pulled through the sewer section. (Image: Culvert pressure unit) As shown in the figure, one sensor is located in the capsule … |
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May 16, 2012 Following the acquisition of deposit data from the individual sections and manholes, the findings are classified and assessed. Below you can see an example of a three-step model for the classification and assessment of data, which has been developed and applied in several research projects.
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May 16, 2012 (Image: Haltung) Important: The section with the highest problem level should be decisive for the determination of a cleaning priority. In the process of prioritisation the deposit quantity and its composition can both be used as equal assessment criteria. |
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May 16, 2012 Based on the description of the drainage system (technical evaluation) and prioritization of the deposit situation in the drainage system, the blending of the cleaning objectives within the scope of the strategic cleaning planning is made possible.
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May 16, 2012 The results show a prioritisation and area ranking which in addition to a technical assessment of the deposits also include environmentally related, operational, hydraulic, economic and other strategic aspects, such as the sensitivity of surrounding structures (hospital, industrial enterprise, etc.). (Image: District ranking) |
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May 16, 2012 The cleaning intervals are set for individual network sections and groups on the basis of
(Image: Determination of the cleaning intervals) |
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May 16, 2012 The Result is a long term strategic cleaning plan that is continually updated based on new operating experience and information
It is highly recommended to increase the cleaning intervals only gradually to minimise the impact of any forecasting inaccuracies. |
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May 16, 2012 The cleaning measures are carried out based on operative cleaning planning in the form of operational or flushing plans. These plans include: a priority ranking of the determined cleaning measures, specifying both the cleaning method of choice and associated cleaning devices and tools
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May 16, 2012 The operational or flushing plan describes when, where and how to clean. "When" and "where" are mostly based on the strategic cleaning plan. The "How", i.e. which method and process parameters are to be chosen for cleaning, requires exact knowledge of the local circumstances.
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May 16, 2012 In accordance with DIN EN 14654, the following information is to be taken into consideration:
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May 16, 2012
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May 18, 2012
[ [EN14654-1:2005]] |
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