Chapter 3 Decision Support Model (IUWS-DSM) - Tubdok

2.1.4.3 conveying system
Chapter 2 · New Conception 23
Water conveying includes raw water transmission, finished water distribution, and used
water and storm water collection. In the conventional idea, they are designed and managed
independently. In IUWS they are considered and planned together in the same time as one
conveying system. It further prompts to construct the distribution and collection systems
simultaneously, which can result in less construction costs and better organisation of urban
underground pipelines. The main components of conveying system are introduced as follows.
Conduits. Pipes and canals are the usual measures for conveying water, where pipes
are mostly used in urban area. In pipe systems, the hydraulic conditions can be pressurization
or gravity. Normally water distribution systems have the pressure pipes and the
sewerage systems have the gravity systems. The canals can be used for the transmission of
raw water and storm water if the space and surroundings are suitable.
As mentioned above, the vacuum system is another method to collect sewage. The
record of vacuum sewerage can be traced back as early as 1868 (Elsevier 2004). As a very
expensive system, the vacuum sewerage can still be cost competitive in the extreme
situation that the area is very flat, the water consumers are scattered, and the ground
conditions are difficult for deep excavation. In the context of our IUWS, vacuum system is
only considered for collecting blackwater. Due to the high cost, earlier vacuum toilets were
mainly applied to the particular situations like in airplanes and submarines. Today they are
more and more applied in civil toilets and thereby, it is a good option to evolve our urban
water systems.
Besides conduits, the ancillary works are necessary. In this work the main components
are considered and involved, i.e. pumping stations, storages, and valves.
Pumping station. Booster pump station is used for upraising or pressurizing the raw
water transmission or finished water distribution systems. The primary requirement of
booster pump station is that the pumped water must remain the same water quality as before.
Lift station is used in sewerage system for lifting urban sewage and storm water. Lift station
has the comparably lower delivery head. Usually lift station has the severe operation
conditions. Moreover, there is the vacuum pumping station, i.e. the collection station, which
is attached to vacuum system for collecting sewage or blackwater.
Storage. Except very small systems, the storage is the essential part of the water
distribution systems with the following purposes, e.g. providing constant water production
and supply against variable demand in the networks, providing emergency supply, and
maintaining the stable pressure (Trifunovic 2006).
In both roof-water utilisation and storm water management systems, the storage plays
the critical role. The storage tank is the indispensable part of the roof-water utilisation
systems, as it helps to supply water through a period, instead of only for one rainfall event.
Moreover, it can even exert significant influence to the sewer downstream (Vaes and
Berlamont 2001). The storage tanks can be divided into three classes: 1. at-grade or
aboveground, 2. below-grade, and 3. integral containers built into a building (Kinkade-Levario
2007).