The story took place in Russia in 2007 and related to
designing of reservoirs intended for drinking water filtering, conditioning and
storage for different industrial, administrative and dwelling facilities.
Background
The aim was to propose new technological
solutions to major industrial companies, relating not only to drinking water
filtering, conditioning and storage, but to purification of sewage discharged
from industrial objects. These solutions were to be implemented by the
customer’s representatives afterwards.
In connection with corrosive wear of drinking water
supply pipelines, that had not been renovated since the USSR disintegrated, and
also stiffening of ecological requirements to purification of potable water got
from water-purifying systems of enterprises, there was a need in development of
a universal technical solution, which would allow to filter and store huge
amount of water, especially in areas with lack of water. Effective normative
limitations for prepared drinking water storage duration in many reservoirs
(not more than 48 hours) led to necessity of installation of large number of
water level sensors in every reservoir and constant quality control. The
existing drinking water reservoirs were technically outdated, and their reconstruction
was economically unreasonable due to necessity of complete renewal of internal
facing, pipelines and stop valves.
My research has shown, that according to
the official statistics, in Russia over 60 per cent of water is consumed by
industry, and the government has adopted a program for water saving
technologies implementation and water reuse (closed water circulation) to drop
this figure. Russia also possesses great reserves of artesian water, which is
not enough used due to lack of sufficient number of storage reservoirs. The
problem of sewage filtering was very keen, because until recently large amount
of runoff came to pools without proper disinfection due to wear of sewage
treatment facilities.
The project was aimed at engineering development of
new facilities for water storage and utilization with an integrated
purification system. This project implied its integration into the existing
water purification system at enterprises and preparation of universal
recommendations on construction technology for this building on territories
with different geology and housing density.
My task was to create a structural layout of
reservoirs with continuous water cycle (water substitution) for getting and
saving high quality water. Also, I had to choose a corresponding water
filtering technology, materials and equipment for its realisation and integrate
it into the developed project afterwards.
Because of inhomogeneity and bad quality of grounds on
the most of the assumed construction site I had to select and rework a technology
of erection of buried reservoirs.
Personally I, as a chief designer, performed work
connected with selection of analogues and prototypes of technical solutions,
their analysis, technical solutions development, designing and calculation of
building structures, selection of ways and methods of their construction.
To detect still water zones, producing negative effect on drinking water
quality, hydrodynamic and mathematical calculations of the internal reservoir
scheme, placement of internal walls and water flow inside the reservoirs were
made by the specialists from the Research and Development Institution of the
Ministry of Defence of the RF and afterwards were tested on a prototype model.
Solution
As I concerned the theme of reservoirs construction
during my study at the University of Architecture & Civil
Engineering, and based on my research of the known types of reservoir storages
for the local settlements near the manufacturing entity, I have chose and
adapted a scheme of several reservoirs with a cascade overflow system of their
filling with drinking water and with vertical water circulation. The advantages
of this system include regular water reserve renovation in all reservoirs and
possibility of additional connection of new large-sized reservoirs to the
existing feed reservoirs.
To check operation of the system and to improve
it, I have made a proposal to test it on a prototype model to decrease the
number of still water zones, which affect organoleptic properties of water. The
involved specialists have detected problems of water stagnation in the upper
part of the reservoir when fresh water comes in. To solve this problem, they
have proposed a scheme of water intake dibhole installation in the lower part
of the tower. I have made some revisions in typical design, lowered the level
of central well burial, and changed the scheme of water admission and water
intake hoppers in the lower part of the building.
I proposed to use block tubings for construction of
the reservoirs to unify elements of reservoir external walls assembly and its
central circular tower, which has reduced erection time and simplified
reservoir construction technology. According to the elaborated work performance
plan, assembly of the block tubings is made from an inventory platform hung up
inside the tower and shifted up as far as the tower is erected, which has a
positive impact on safety.
Absence of steel embedded items and metalware inside
the reservoir excludes works on their metallization (zinc coating protection
against corrosion).
I provided a possibility of extending capacity of a
reservoir already being in the process of operation, having prepared a
technology of wall expansion to necessary volume with simultaneous increase of
bearing capacity by insertion of a coaxial supporting cylindrical tower.
To additionally simplify the construction, I have
minimized the number of stop valves and water level sensors in the reservoirs
with the help of the cascade overflow system, enabling to control only the last
reservoir.
To provide remote industry and populated areas
with potable water and to filter and condition water, I have proposed to put
filtering backfill inside the central tower. Here I have realized my previous
research in water purification field (RU 2160231 and RU 2163565 – “Drinking water purification and conditioning
tank”).
Connection of additional reservoirs has increased
significantly reliability of the existing household water supply system.
Organoleptic properties of purified water remained acceptable for a long time
due to regular water circulation and absence of still water zones. After the still
water zones had been eliminated, there was no necessity in regular cleaning of
the internal walls of the reservoir from microflora putrilage, which also has
reduced exploitation cost.
When I designed water reservoirs for nuclear plants to
solve the problem of radioactive water utilization, I had to provide leak
tightness. In my scheme of a reservoir for contaminated water storage,
radioactive water comes in the internal tank of the reservoir, and the external
well contains clear water and serves as a natural buffer preventing penetration
of contaminated liquid outside the building.
Also I have finalized internal building structure and
provided access for service staff to take preventive measures. To reduce cost
of construction without loss of water purification quality, I have reduced
quantity of metal by replacement of reservoir stainless steel lining with
fibrous concrete.
Also the reservoir system could be used at new
nuclear power plants as an alternative to the pools of bubble flask type for
the emergency reactor shutdown system. I have sent these proposals to one
nuclear power plant in Russia for making changes in project documentation of
construction of new blocks. Additionally I have modified technical solutions to
use the building for utilization of other liquid and solid radioactive waste,
for example, reactors taken from nuclear-power submarines.
To build buried reservoirs under severe
engineering and geological conditions, I have chosen and almost adopted a
technology of drifting works. This method of cylindrical reservoir construction
included assembly of two coaxial internal and external drop caissons and their
sinking by their own weight with a swamp weight. As a result, influence of
infavourable engineering-geological conditions on drifting quality is reduced,
and sizes of the construction site become less due to usage of internal caisson
space for building erection.
This method was supplemented in the shortest possible
time, when the buried reservoirs were being
built on water-saturated dust sands. Suffosion (washing-out of tiny particles
of ground with pumped-out water) took place during construction in a zone with
a high groundwater level when pumping-out water, which threatened integrity of
grounds and foundations nearby. I have applied the drifting
method with a drop caisson in thixotropic jacket with underwater excavation by
using special heavy automatic grabs. The main difference from the typical drop
caisson construction method is that underground water is not
pumped out during ground development. Ground is
fed onto the surface by caterpillar cranes with capacity of 25 t together with
large-span gantry cranes. Water, removed with the developed ground, is forcibly
made up of pouring within the limits of the caisson contour to keep the natural
groundwater level. In this case there is no necessity of a cutoff curtain (a
wall in ground), which makes construction cheaper.
When geology of the construction site is
saturated with big boulders, I offered to supplement this method with
construction of a forward caisson of lesser diameter, 5-6 metres deeper than
the main caisson, with a sand-gravel filter. This caisson should be used as a
structural element of the building, performing two functions. Firstly, when the
main caisson meets a boulder and hangs up, one-time short pumping-out of water
takes place through the small caisson to destroy the boulder by a nonseparable
method. Secondly, after the main caisson reaches the design mark, the bottom
can be build without underwater concreting of the obstruction, which reduces
its cost and material consumption. While the bottom is being built, short-term
water depression is made through the pilot borehole filter, and after the
bottom of the original hole is built, the pilot borehole filter is concreted
under water.
It
should be noted that the pilot borehole increases cost by 10 per cent and
extends the period of construction of a typical reservoir by 2 months, but
usually this method is the only solution for places with dense industrial
development. Also this method can be used for construction of cylindrical buildings
of different purpose.
Additional
time and money can be saved owing to the possibility of performance of detailed
engineering and geological surveys simultaneously with construction, because
permanent monitoring and correction of verticality and speed of external
caisson walls immersion allows to eliminate slants immediately. Volume of
assembly works inside the well at a zero point can be augmented to the maximum
before immersion.
Summary
As a whole, the project has played a big role in
region development, as the technical concepts, which I suggested, were realized
afterward during construction of different buried objects. The technical
solutions, got in the course of designing, connected with water circulation in
a reservoir, and the method of buried reservoir construction were also used in
the Candidate's dissertation by the specialists from the 26 Research and
Development Institution of the Ministry of Defence of the RF. Work
on this project gave me an opportunity to apply wide-ranging knowledge of
engineering and related areas. I considerably deepen my knowledge of
underground construction, geology and hydrodynamics. Skilful job related to
important structures determination and concentration on them enabled to save a
lot of time. My leading role in the project allowed to implement my
previous ideas formalized in Russian patents, that indicate to their technical
correctness. The given project allowed me to broaden my knowledge in buried
objects construction and improve my level of team work ability.
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