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Sofia's model approach

Water: Privatisation

Residents in the Bulgarian capital Sofia are warming to the idea of privatised water. Margo Cole reports.

With the negative response to water privatisation in the UK, what company would want to go through that experience again?

But that is exactly what United Utilities has done by taking on a 25 year concession to operate water supply and sewerage provision in the Bulgarian capital Sofia.

Its joint venture with International Water marks the first time a private company has been involved in the country's utilities, and it is being watched very closely by Bulgaria's media and 25 other municipalities which are thinking of following suit.

Two years into the concession period, opinion is warming to Sofiyska Voda and the company is confident that the improvements it plans will result in customers being more than satisfied with the public sector involvement.

Sofiyska Voda is 75% owned by the joint venture and 25% by the municipal water and sewerage operator ViK, its share made up from assets such as buildings, desks and vehicles.

The water supply and sewerage networks - pipes, manholes and treatment works - are not included in the deal and remain the property of the municipality.

The mayor of Sofia employed Hyder as technical consultant for the contract, as a result of which the concession agreement mirrors much of the UK's regulatory framework - especially on levels of customer service. However, because very little was known about the extent and condition of the network, there is one major difference.

'The technical specification included a requirement to carry out modelling because, at the time we submitted the bid, it wasn't possible to understand the long term investment requirement, ' says Jim Southworth, chief executive officer of Sofiyska Voda, who put toether he technical bid on behalf of UU.

The concessionaire is committed to spending US$156M within the first 15 years of the contract, but the agreement stipulates that two and a half years into the concession period Sofiyska Voda must have completed computer models of both the water supply and sewerage networks, followed by a six month period to agree the major investment needs.

At the same time the company must also ensure the day to day running of the system and meet tough targets for improvements in customer service.

Sofia sits on a plateau between two mountain ranges.

Some 80% of its water comes from a giant 650M. m 3 capacity reservoir behind the Iskar dam high in the mountains to the south of the city.

The remaining 20% is supplied from the smaller 15M. m 3 capacity Beli Iskar dam in the same region, with the water simply disinfected and fed to the southern edge of Sofia.

The bulk of the water goes through two treatment plants and is then fed through the city by gravity, with pumping only required in the far north of the capital. Wastewater flows through the sewerage system by gravity to a single treatment works on the northern edge of Sofia.

The 1.2M residents are used to paying for their water supply and wastewater disposal, with all dwellings metered, and only 10% of those connected exempt from payment. Tariffs are approximately 16 cents per litre of potable water and less for sewerage and wastewater treatment.

The city's first sewerage system was built at the end of the 19th century, with pipes collecting discharging sewage directly into the Iskar River. As the system was modernised these discharge points became overflows, with the main flow connecting to the treatment works. However the overflows are still regularly called into use during storms with large volumes of untreated sewage going into the river.

In the long term Sofiyska Voda may decide to separate storm and foul sewage or build storage capacity into the system. Short term, though, there are other priorities, including day to day network maintenance and cutting down on 'unaccounted for water'.

Every month 20M. m 3 of potable water enters the network, but only 8M. m 3makes it through the water meters.

Although a 65% loss rate is by no means the highest in Bulgaria, it is significant enough in political, environmental and financial terms for stringent reduction targets to be incorporated in the concession agreement. By year six that loss rate must be halved.

Jens Meier-Klodt, operations director of Sofiyska Voda, believes 60% of the disappearing water can be accounted for by leaks and the remainder by commercial losses such as illegal connections and poor metering.

Data collection for the modelling phase of the programme is giving Sofiyska Voda a better idea of the physical layout of the network and picking up some of the illegal connections. At the same time 170 new valves have been installed to restore the water supply network to the original 'zones' in which it was first laid out.

'The system was quite nicely designed, but it spread over the years, ' explains Meier-Klodt.

Restoring the city to four supply management areas - each split into eight demand management areas - will give Sofiyska Voda a much better chance of identifying where the water is being lost.

Running water on the streets of Sofia is a familiar sight, with residents used to the disruption of burst pipes and leaks. Much of the network was built using poor quality steel and asbestos cement pipes, resulting in up to 70 leaks a day - or 2,000 every month.

When Sofiyska Voda took over the network it inherited 400 outstanding unrepaired leaks and a 300 strong team of pipelayers, welders and drivers whose job it was to fix them. At the beginning of 2002 the company decided to outsource this activity completely.

'After one year of the concession we had the impression that the performance of network maintenance wasn't improving, ' explains Meier-Klodt. 'There was very poor safety awareness and quality was low.' Network maintenance was traditionally rife with low level corruption such as stealing materials and taking money from customers to speed repairs. 'We decided that we had to do a complete break, ' says Meier-Klodt.

A very carefully controlled bidding process led to the appointment of four different contractors - one for each of the supply management zones.

Staff and equipment were transferred to the contractors with one year's guaranteed employment.

'It looks as if it really is very successful, ' says Meier-Klodt.

'We are now paying unit prices and are monitoring and auditing to ensure they meet their contractual targets.

'Understandably there was some criticism from the outsourcing because this was a major change for the organisation. But it wasn't done for the sake of outsourcing, and we are actually spending more money.'

Although the major investment programme will not be finalised until next year when the models are complete, Sofiyska Voda has already spent over US$28M on improvements. Of this US$6M is going on repairs to the Beli Iskar dam, US$5M on network rehabilitation and pipe replacement, US$4M on items such as valves, chlorination stations and pumping equipment, and US$1.6M on new house connections.

Another US$3M has been set aside for rehabilitating the sewerage network and US$900,000 for new meter installation - the start of a programme that will see all 80,000 of the city's water meters replaced in five years.

Considering the options

Sofiyska Voda has seconded engineers from UK consultant Ewan Associates to manage data collection and build computer models of both the water and wastewater networks and to use these models to identify the long term investment options.

Data collection includes information from short term and long term flow meters and rain gauges, physical data from manhole surveys and CCTV, paper and GIS records of the networks and population information. Martin Parker, wastewater modelling project manager, says: 'The underlying base data that you would assume in the UK you just don't have here.'

From a standing start of just three people, Parker has built up a team of 28 staff made up of eight locally qualified engineers and 20 working in field crews. A similar sized team has been recruited by Parker's colleague on the potable water side, Craig Demanuele.

Initial models incorporate all the information needed to make major investment decisions, rather than being complete models of the entire network. While the potable water model includes all pipes down to 200mm in diameter, it is slightly more difficult to identify which sections of the wastewater network have strategic implications. As Parker says: 'We want the information that will enable us to look at the strategic stuff, like connecting new towns, but in some areas smaller pipes may be an investment driver.'

As a result 5,000 or 6,000 manholes have been surveyed out of the 25,000 located throughout the city and the model includes all pipes over 1m in diameter, plus areas identified as crucial to long term investment.

The strategic models must be completed by March 2003, and all the options put forward and agreed by September 2003. Parker says: 'For me the optioneering is easy - it's making the model that's the hard part. If we get our model right the options will drop out.'

Reading the meter UK data collection specialist IETG won two contracts, worth US$335,000, to provide all the sewer flow and rainfall monitoring for the Sofiyska Voda project.

The first was for permanent long term flow monitoring equipment at key locations on the sewerage system, made up of eight ADS monitors and seven rain gauges, providing base data for the hydraulic model. There is also an Accusonic monitor at the treatment works providing total volumetric flow information.

Subsequent work involved a short term drainage area study using 50 standard flow monitors, 10 ADS bidirectional, enhanced accuracy flow meters and 25 rain gauges installed last spring to catch the winter/spring weather. These were supplied with a thermostatically controlled heater so they could cope with winter temperatures well below freezing.

ADS flow meters are designed for long term or permanent flow measurement in open channels and sewers, and can measure peak velocity and depth using three sensors: a Doppler sensor in the invert of a pipe; an ultrasonic sensor on the crown or soffit; and a pressure depth sensor either in the invert or out of the flow to avoid physical disturbances or silt build up.

Data is stored in a logger and can be retrieved manually or by telemetry. The monitors can be configured to record data at one, two, five, 10 or 15 minute intervals.

Accusonic flow meters measure the effect flowing water has on the differential time taken for a pulse of sound to travel upstream and downstream between a pair of submerged transducers. A pulse of sound travelling diagonally across the flow in a downstream direction will be accelerated by the water and, conversely, a pulse travelling upstream will be decelerated by the water.

It is a very accurate method of measurement: typical accuracy in a pipe flowing partially full to surcharged is between 2% and 3% of actual flow rate under open channel conditions and 1% to 1.5% under surcharge conditions.

IETG had two full time staff working for four weeks to install the equipment and train local teams to collect the data from the long term monitors.

The short term monitors were all installed by IETG and the data collected and processed in Bulgaria by IETG staff over an eight week period.

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