IMPLEMENTATION OF INTERNATIONAL TECHNOLOGIES AND KNOW-HOW FOR
IMPROVEMENT OF WATER SUPPLY IN ALYTUS, LITHUANIA
B. Paukstys*, E. A. Hansen** and Rimantas Mockus***
*Hydrogeological Company “Grota”, Eisiskiu plentas 26, LT-2038 Vilnius, Lithuania, e-mail:
bernardas@iti.lt
** DHI Water and Environment, Agern Alle 11, Copenhagen, Denmark, e-mail: eaa@dhi.dk
*** Company "Dzukijos vandenys", Pulko street 75, LT-5840 Alytus, Lithuania
ABSTRACT
This paper describes preliminary results of an international project, conducted in co-operation
between Denmark and Lithuania to solve complicated municipal drinking water supply
problems. A decrease in industrial production has led to a drastic drop in water consumption,
and previously designed water supply and treatment facilities are too large. Natural
hydrogeological conditions cause clogging and shorten the lifespan of groundwater extraction
wells. Ways to optimise water supply and improve water quality in the city are sought.
International experience and funding are used to address these and many other issues.
KEYWORDS: Groundwater, leakage, water supply, international co-operation, well field.
INTRODUCTION
Groundwater is a sole source of potable water supply in Lithuania. There are 94 municipal
well fields that supply groundwater to 54 major cities. Alytus city of southern Lithuania
representing a complicated set of natural and human induced environmental problems has
been selected as a pilot site for international project.
Hydrogeological Company "GROTA", Lithuania initiated a project "Improvement of Alytus
Water Water Supply, Lithuania" in 1998, in co-operation with DHI Water and Environment,
Denmark. The project is financed by the Danish Environmental Protection Agency, Danish
Co-operation for Environment in Eastern Europe.
The following five main outputs with a range of activities for achieving immediate objectives
of the project have been defined:
1. Well field management plan;
2. Plan for rehabilitation of water supply network;
3. Action plan for water saving at main water consumers;
4. Evaluation of existing drinking water treatment facilities and preparation of rehabilitation
plan;
5. Pre-assessment of the sewer system and an action plan for inventory of the system.
Preliminary results of two first outputs are discussed in the paper. More results will be
achieved in the project and presented during the conference.
THE PROBLEM
Alytus, the sixth largest city by the number of inhabitants in Lithuania (77 thousand) is
supplied by potable groundwater from 3 well fields: Vidzgiris, Radziunai and Strielciai with
approved by the State Commission groundwater resources of 66.3 thous. m3/d. 93,7 percent of
population or 72221 people are connected to the central water supply and almost the same
amount (71601) to wastewater collection network.
3
amount of consumed water, thous. m /day
Water supply and water distribution system in the city has been designed to be able to safely
supply with water the growing industrial city for a perspective of year 2005. Unpredicted
political-economical changes in the country 10 years ago imposed, however, serious
corrections of the water supply sector. After the re-establishment of independence in 1990
economical production and groundwater consumption over all Lithuania, including Alytus
City, has dropped down drastically (figure 1).
30
25
20
Inhabitants
Industry
15
Total
10
5
0
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
years
Figure 1. Groundwater consumption changes in Alytus.
The reasons for such a drop of water consumtion are two-fold:
1. Decrease of industrial production and
2. Installation of water meters in the houses and flats
All three well fields are located in the valley of the river Nemunas. Half of water is estimated
to be infiltrated surface water. The Nemunas River is highly polluted with an upstream
catchment area extending into the Beylorussia.
Geological and geochemical situation of the well fields is favourable for well screen clogging.
In 30 years of exploitation of the main Alytus well field more than 100 wells have been redrilled. In some places wells were re-drilled 4-5 times. The durability of the wells varies from
several months to 14 years, average being 4-6 years.
The main water supply problem today is high operation costs due to a short lifetime of the
wells and water leakage from the distribution network.
DESCRIPTION OF THE WELL FIELD
Strielciai well field is the main well field of the city where well clogging problems cause
serious economical problems of groundwater production. The project therefore is focusing on
this well field when solving well clogging issues. The well field is located 3 km north from
Alytus in the valley of Nemunas River on the right bank. Total length of the well field reaches
3200 meters. There are 22 production wells in the well field, which produce 8-10 thousand
m3/d of groundwater. Exploitation of Strielciai well field strated in 1979.
Geological – hydrogeological conditions
Quaternary sand and gravel aquifer (Zemaitijos-dainavos, agII-I zm-dn) located along the
valley of the Nemunas river is main production aquifer in Strielciai well field (Figure 2).
Water bearing sediments are formed by grey and greenish gray multi-grained sand, sandgravel and gravel-pebble sediments. Coarse-grained fractions prevail in the section. The
aquifer is underlained by Dainavos moraine till (agIdn) or paleogenic clay and silt. Sporadic
distribution and low thickness clay (up to 13 meters) influences hydraulic connection of
aquifer with the upper Cretaceous confined layer located on the lower level.
Before the start of the well field exploitation piezometric level of aquifer was in depth of 0.421.1 meters. Water level in wells during dry season stabilizes at 2-6 meters above river water
level. Seasonal fluctuations of water levels in wells reach 1.8 meters.
The aquifer is confined on all territory of the well field. Water pressure varies from 12.6 m to
43 meters. Specific capacity of wells is 1-3 l/s and sometimes reaches 8 l/s.
Figure 2. Geological cross-section of Strielciai well field
Groundwater quality
Water from production aquifer is fresh, with main cations and anions not exceeding
maximum permissible concentrations (MPC) of drinking water standard. In average total
dissolved solids in wells reaches 370 mg/l, in water mixture – 403 mg/l. The average pH
values are 7.3-7.5. Permaganate index is very different and fluctuates from 1.2 to 22.9 mgO/l
in wells, in average making 3.84 mgO/l. Predominant permanganate indices (moda) in wells
is 3.36 mgO/l and do not exceed MPC for good quality water. The maximum permanganate
indices in water mixture reach even 47.6 mgO/l as recorded in 1992, although average and
predominant values of indirect organic material index do not exceed set limits for good
quality water.
Increased concentrations of iron are detected in Strielciai as well as in other well
fields. Amount of Fe2+ and Fe3+ in wells fluctuate from 0 to 7.7 mg/l. Limits of iron
concentrations in wells set by standards are 0,3 mg/l. Mediana and moda of iron compounds
reaches 3.21 mg/l and more than 10 times exceeds MPC. Similar situation is observed in
water mixture where average values of total iron is 3.7 mg/l, and mediana 4.1 mg/l. Water of
such quality could not be used for drinking purposes without de-ironing.
Well clogging
It was concluded that the main reasons for well filter clogging in the well field are as follows:
1. Clogging starts from mechanical silting followed by the chemical and bacterial clogging
in a course of exploitation.
2. The lithology of water bearing sediments at the well fields is heterogenous vertically and
horizontally. This creates different filtration conditions in the aquifer and makes difficult
selection of gravel pack.
3. Filter type also influences well clogging. The lowest reduction of specific capacity is
observed in the wells with rod-wire type of filters. Worst filters are those made of
stainless steel or brass net. Average working period of rod-wired filters is 6.5-10 years
while net filters last for 3-6 years. Well aging also depends on filter diameter and length.
Larger diameter filters work longer.
4. Mixing of water with different chemical and gas composition contributes to chemical and
biochemical clogging of filters. The reason of clogging is changes of chemical equilibrium
due to aquifer aeration and iron bacteria and algae activities. Eh and pH fluctuations
influence direction of chemical reactions.
5. Chemical clogging of near filter zone is accelerated by biological activity of iron bacteria.
Several types of iron bacteria was detected in Alytus well fields, namely Leptotihrix
ochracea, Gallionella and Siderocapsa. Biological analysis of water samples detected
from few to 0.2 million bacteria per liter in Strielciai well field. In some water samples
also algae has been detected.
Intervention of international project
Drilling works
The drilling works includes drilling of monitoring wells and a demonstration well in the
Strielcai well-field and also pulling of an existing filter for examination for clogging and
rehabilitation of existing clogging wells. The demonstration well is established with noncorrosive 10” PVC-casing. The filter is the stainless steel Johnson-filter to provide maximum
open area of the filter and to give good possibility to future filter maintenance. Sorted gravel
pack (diameter 1-2,5 mm) is used. The results of preliminary pumping test show that the flow
rate of the well is 28 l/sec with a drawdown of 17 m and specific capacity of the well is 1,65
l/sec for 1 m of drawdown
For inspection and sampling of material from a clogging filter the old filter from the existing
well was pulled out. The filter was examined visually, samples of filter material collected and
sent to laboratories in Lithuania and Denmark.
TV-inspection
TV-inspections of 7 production wells at the well field were performed with the assistance of
the Danish TV-inspection company LMJ A/S. In two of the wells visibility was very poor.
Apart from this the inspection was successful. TV inspection shows clearly the degree of filter
and pipe hole clogging.
REHABILITATION OF WATER SUPPLY NETWORK
The water supply distribution network in the Alytus City is old and corroded. This leads to
large water and energy losses in the distribution system and also brings brown colour
groundwater to the tap of the consumers. The estimated leakage from the supply system is
30%.
In 1999 the total length of water supply pipelines was 106 km. 85 percent of pipelines are of
satisfactory quality, 9% (or 8.5 km) of pipes requires renovation and 6% (5.6 km) should be
changed as soon as possible. It is estimated that for 1 km of pipeline 0.6 accident happens
annually. The reasons for accidents are:
78% - damage (corrosion) of pipes
26% - damage of pipe connections
6% - damage of valves.
150
Pipe breaks
100
Connections
Valve
repairs
50
0
1996
1997
1998
1999
2000
Figure 3. Accidents in water supply network
Leak detection
The project has purchased DANTEC leak detection equipment. The equipment consists of
DANTEC Leak Locator Type 10S, hydrophones for plastic pipes, spindle-locator and cable &
pipe locator. The equipment was delivered in June 2000 and theoretical and practical training
for the use of the equipment was organized. Two teams of operators from the Alytus Water
Company were trained.
The leakage detection in the water supply net was made in two steps:
 Mapping. In this step each valve-well in the streets was visited.
 Pinpointing. In this step the leak detection team investigated the areas for possible leaks
using the full leak detection equipment.
75 places for potential leaks were detected and 39 leaks repeared during the programme. It is
planned that the employees of Alytus Water company will perform leakage detection on
permanent basis.
Night flow measurements
The measurements of night flows is one of the widely used actions that can be taken to
identify leakage problems. The minimum night flow is usually found to occur between
midnight and 4 am when the consumption in the network is at its lowest. The assessed night
water use can be split into three components:
- domestic night use
- non-domestic use
- large users
Normal domestic night water use represents predominantly water used in the toilets. Water
used for making coffee or tea makes a small portion and is usualy ignored. Non-domestic
water users from unmanned fire/police stations, banks, churches, shops, offices to hotels,
hospitals, public toilets, etc. All these users were counted in Alytus in order to exclude them
from the total night water consumption.
Night flow measurements were performed in July- October, 2000 and some control
measurements were continued during the October. During this time full town has been
covered.
Figure 4. Total night flow in July-October, 2000
Average
Linear (Average)
200,00
150,00
100,00
10.22.00
10.15.00
10.08.00
10.01.00
09.24.00
09.17.00
09.10.00
09.03.00
08.27.00
#N/A
08.13.00
08.06.00
07.30.00
07.23.00
07.16.00
07.09.00
50,00
07.02.00
m3/hour
250,00
Increasing rate of nightflow could be explained by the fact that more people return to their
flats after the summer holiday and night water consumtion increases.
Water metering in the flats
In 1992-1993 inhabitants of Lithuania had a possibility to privatise their flats buying
them from the state. The appartment privatization process was immediately followed
by the installations of water metering devices in the flats. This process had both
positive and negative results. Positive was that:
- water users became independent from the bad quality, leaking pipes and pay
only for water they use;
- water consumption can be regulated by the consumers;
- smaller water meters can more accuratelly measure small water
consumption;
- dripping water taps and leaking toilet tanks are repaired.
Negative consequencies are:
- there was no economical benefit of meter installation in the flats because
the installation and checking costs are higher than water which is saved;
- large number of meters (sometimes several in one flat) substantially
increased cost of their maintenance and reparation;
- there is no procedure for checking the accuracy of water meters in the flats;
- the meters are not protected from the impact on readings.
The individual water meters are only duplicating the readings of house-inlet meters
which are installed in all multistory houses. Water supply company is metering the
supplied water only by inlet meters. The evaluation carried out by the Vilnius
Technical University shows that the difference between the readings of inlet meter and
sum of the flat meters is 32 per cent in favour of inhabitants. Inhabitants pay for water
according to readings of their flat meters.
Today Water Supply Company has to cover difference between the inlet meter and sum of flat
meters. The company is trying to convince local and national authorities and inhabitants that
they have to pay for water according to calibrated inlet meters. But this is more political issue.
CONCLUSIONS
The long term purpose of the international project "Improvement of Alytus water supply,
Lithuania" is to create an integrated water supply and energy management system, strengthen
the institutional capacity, improve water supply infrastructure, reduce significantly
groundwater losses, save energy and reduce groundwater pollution. These problems are an
important issue not only in Alytus City, which was chosen as a pilot area for the project but
all over the country. Therefore it is expected that results of the project will be useful for
soving similar tasks in other places.
Although far from the end the project has proved already that interantional co-operation is
beneficial for both sides not only from scientific, financial and social points of view. Such
cooperation combines knowledge of two different schools, and even worlds: western and
eastern. This combination helps to better evaluate the problem using sometimes completely
different atitudes.