Lake Ohrid secures initial project funding
Funding for a sewage treatment project in Albania has followed detailed feasibility studies. Project manager Susanne Seitz and Dr Andreas Zysset, director of the water division at Ernst Basler and Partners explain the process.
The city of Pogradec lies on the shore of Lake Ohrid, which is shared by Albania and Macedonia and was declared a UNESCO World Cultural and Natural Heritage Site in 1980.
A feasibility study on the lake discovered that sustainable protection can only be achieved by preserving its oligotrophic condition. Thus, the phosphorus input into the lake - to a large extent the result of untreated sewage - must be reduced.
Project consultants Ernst Basler and Partners assessed 11 concepts for sewage collection and treatment on the lake's Albanian side. The type of treatment and the connection possibilities were varied.
The concepts were then compared with regard to their costs, their environmental impacts as well as the operation and maintenance demands of the systems.
The Local Treatment in Pogradec proposal, which plans to connect all Albanian villages within a distance of 20km from Pogradec to a treatment plant near the city, had the highest rating.
But in addition to the concept's benefits, there were also risks, including the operational and maintenance demands of the system (which would be the first of its kind in Albania).
As a result, a binational Evacuation to Vraniste in Macedonia concept was given further consideration. The operation of the treatment plant, the most complex element of the system, is more predictable as the plant in Vraniste, Macedonia is already in operation.
The binational solution connects all villages along the lake shore and in the plain of Pogradec to the existing treatment plant in Vraniste. Secondary gravity sewer systems in the villages dewater into shoreline pumping stations.
The main pressure pipeline starting in St. Naum (Macedonia) and ending in Vraniste (Macedonia) connects all Albanian and Macedonian villages along its route.
Polyethylene mains ensure a high service life and good resistance against physical and chemical influences. The pumping stations have individual reservoirs in order to allow for repair and maintenance work on the primary sewer system and to level out the peak flows in the system.
All pumping stations are equipped with submersible sewage pumps, resulting in easier handling and replacement. A high-voltage power supply line links all pumping stations to establish a reliable power source. The mechanical and biological stage of the existing plant in Vraniste is extendible to meet future needs. The increase in plant size will have a significant improvement on the process stability and its cost efficiency.
The treated wastewater runs into the river Crni Drim, Lake Ohrid's outflow, and is thus removed from the lake's catchment area.
In the local solution the villages alongside the lake are connected by a pumped primary sewer line, with pumping stations and balancing tanks at each village. The city of Pogradec and all other villages along the lake shore and in the plain of Pogradec dewater to a central treatment plant near Pogradec.
The smaller villages on the western shore near the border represent an independent sewerage zone with a reed bed for sewage treatment. The main line is shorter and has smaller pipe diameters than the binational solution.
The proposed treatment plant in Pogradec foresees an activated sludge process in sealed earth ponds with total oxidation of organic matter and a substantial biological phosphorus elimination.
An optional chemical phosphorus precipitation may easily be added as needed. The treated water is released into Lake Ohrid. Part of the sludge is used as a liquid fertiliser for agricultural purposes. The remainder is dewatered and humified in sealed polders.
The whole wastewater collection and treatment system in the Pogradec region could be managed by a newly constituted joint drinking and wastewater enterprise.
The first phase of both solutions concentrates on solving the sewage problem of the city of Pogradec. For this phase benefits and risks on Albanian territory were calculated for both solutions.
The comparison of the relative criteria for the first phase shows a clear advantage for the local solution with three exceptions:
- The environmental benefit of the binational solution is slightly higher because wastewater is removed from the lake's catchment area;
- Transboundary co-operation benefit is higher because of the binationally used facilities which further promotes the protection of the lake;
- A higher environmental risk of the local solution due to a possible failure of the treatment plant in Pogradec which releases all of the pollutant load into Lake Ohrid.
Giving equal weights to all indicators, the overall rating of the local solution is almost double the rating of the binational one.
A workshop on the two investigated wastewater concepts was held at Lake Ohrid in February 1999 with representatives of the Albanian and Macedonian Governments as well as project stakeholders. The quantitative assessment of all relevant benefits and risks - financial, socio-economic and environmental - proved to be a great help in dissolving entrenched debate on wastewater systems.
In the course of the workshop a constructive and co-operative discussion prevailed. It was agreed by all parties involved that the local system is preferable to the binational one, based on its considerably lower unit costs, its suitability for project phasing and its lower regulatory requirements.
The slightly higher environmental benefit of the binational system is outweighed by its technical and financial risks.
The Albanian and Macedonian delegations signed a joint statement to fully involve the binational Lake Ohrid Management Board and to undertake joint efforts in finding additional funding for future project phases.
Construction of the infrastructure is planned to begin at the end of this year. The treatment plant is expected to be put into operation in 2003.
|Environmental benefit||P-elimination||The amount of phosphorus kept from entering Lake Ohrid by the proposed wastewater system.|
|Public Health benefit||People served||The number of person-equivalents served by the project on Albanian territory.|
|Economic benefit||Salaries created||The volume of salaries generated by the operation of the project investment on Albanian territory.|
|Transboundary co-operation benefit||Incremental transboundary investments||The transboundary investments effected by the project to protect Lake Ohrid.|
|Infrastructure risk||Length of primary collector||Compares the failure rate which is proportional to the system length and its complexity. Shows the length of the primary sewer system and it's power supply. The sensitivity to damage and power outages is proportional to the system length.|
|Equipment risk||Yearly discharge rate due to system failure||The pollution of the lake due to involuntary discharge of untreated wastewater.|
|Financial risk||Dynamic production cost||Compares the dynamic production cost for treated wastewater.|
|Investment control risk||Total investment cost per persons connected||The long term fixed capital cost.|