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Mostar Urban Environment and Water Quality Plan June, 2006. Mirko Šarac, B.Sc.C.E. The World Bank.
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Mostar Urban Environment and Water Quality Plan June, 2006 Mirko Šarac, B.Sc.C.E. The World Bank
1. IntroductionThe City of Mostar, is one of the largest cities in Bosnia and Herzegovina, where live around 100.000 inhabitants (according last census from 1991 in Mostar City lived 126.628 inhabitants). There has been no solved sewerage system. Only some parts of town (mainly central urban zone) are provided with sewers (in total approximately 50 km with about 35 discharges which directly flow to river Neretva). Poorly operating septic tanks and cesspits are still in use throughout the area. In addition to the domestic waste dicharges, wastes from industries (aluminium, textiles, metals, woods and others).
Numerous studies have been performed to solve this problem such as collecting, transport and treatment of wastewater. The general rationale were: • Connect all users (domestic and industrial) in the urban area of the Mostar Valley to a central sewerage system; • Establish a gravity interceptor system running from north to south, if possible; • Provide a proper functioning sewer system, especialy with respect to maintaining adequate slopes and velocities in the sewers; and • Provide a suitable level of protection for the Neretva River.
►The overall goals of the wastewater improvement program for the Mostar Valley service area include : • Ensure preservation of natural ecosystem; • Improve the conditions within the middle reach of the Neretva River; • Improve the health of the area residents; • Ensure the preservation of the downstream areas, where the Neretva River is directly or indirectly being used for water supply, irrigation, fishing as well as other uses by numerous towns and smaller settlements; and • Develop an implementation program and financial plan that is affordable.
Specific objective ► to prepare a phased implementation program for rehabilitating, upgarding and investing that will meet stakeholder-agreed, affordable and suistenable objectives for urban environmental and water qualiy goals.
2. Project Need • A primary need for an improved wastewater collection and treatment system in the Mostar Valley is to improve and protect the sensitive Neretva River ecosystem, which includes globally significant wetlands downstream near the Adriatic Sea. • In addition, the project is necessary to protect the health of the population of Mostar and downstream users, and to revive the economy after devastating of the war. • As the largest river of the Adriatic basin, the Neretva River is an ecologically significant resource of international importance.
The lower Neretva valley contains the largest and the most valuable remnants of the Mediterranean wetlands on the eastern Adriatic cost and is one of the the few areas of this kind remaining in Europe. • These estuarine areas (Park of nature "Hutovo Blato" and Neretva Delta) are considered regionally significant wetlands within the Mediterranean and are globally significant wetlands under the Ramsar Convention. • In addition to these wetlands, the Neretva River is a significant ecological resource, because of the many protected fish species that it supports, including endemic Adriatic trout. • In total, 7 fish species found on the International Union for Conservation of Nature nad Natural Resources (IUCN) Red List, and 4 listed as Protected by the Bern Convention are found within the river.
The current practice of discharging untreated wastewater to the Neretva River has serious long-term implications for the Neretva River ecosystem and the sensitive downstream wetlands. Nutrient reduction is one of particular concern with regards to protection of the river and wetland ecosystem. • If untreated wastewater continues to be discharged to the river, nutrient loads will increase, and the river and wetlands will be subject to eutriphication. • EU Council has established effluent standards for discharge of nutrients to sensitive areas under Directives 91/271/EEC and 98/15/EEC. The long-term goal of wastewater treatment and nutrient removal of City Mostar is to comply with EU standards.
Except nutrient reduction wastewater treatment is needed to remove suspended solids, coliform bacteria, and toxic substances, including heavy metals from the river. • Today, the Neretva River is contamined with faecal coliform levels that exceed EU coliform
The Neretva River is not used for consumption in Mostar, downstream wells located close to the river supply drinkig water to numerous towns and settlements. It is possible that water from Neretva can penetrate these wells, degrade drinking water, and pose a risk to downstream populations. Wastewater treatment is essential to meet the EU standards for coliform bacteria, which will improve the sanitary conditions for Mostar residents and downstream users. • In the Mostar area, septic tanks, cesspits and latrines are still in use, which also presents a great danger for the health of the population.
The project will create a variety of employment opportunities both directly from the implementation of the project, and indirectly by being attractive to new business and industry. The phased approach of the project ensures long-term employment opportunities in the area that has a 40% unemployment rate and continues to suffer economically. Tourism will also benefit; the project will be consistent with current efforts to restore the City and reestablish the tourism industry to pre-war levels, which will also provide jobs and stimulate the weak economy.
3. Existing Situation The City covers area of 13.950 hectares and comprises 3 main areas: Bijelo Polje (northern valley), central area and south valley. • The Neretva River flows through Mostar and is the key feature in the area. • The war occured from 1992 to 1995 resulting in large emigration. As result of the war, close to 90% of the city industrial capacity was shut down or destroyed and is still out of operation.
The largest population concentration is in the central urban zone, which covers an area of 3.882 ha, including about 1.000 ha of the southern industrial zone. • This zone had a population of approximatelly 90.000 inhabitants (1991 census), representing roughly 70% of the entire population of Mostar. • The existing wastewater network in Mostar covers only the central urban area that serves about 50.000 inhabitants who represent only the half of the entire population living in Mostar valley today.
In the others areas of the Mostar valley only selected industrial plants have a drainage system for wastewater while the others independently dispose into the ground or into small rivers or streams (such as Radobolja, Jasenica, Buna and Bunica) that flow into the Neretva River. • Development of the wastewater network has occurred in a disorderly fashion. Newly built urban areas simply connected themselves to the existing network which meant that previously constructed collectors became too smal for the new capacity. The service area has enlarged and land use has also changed. The urbanization of unused and green areas has increased runoff from these areas that in turn has increased quantities in the system. As result of this the capacity of existing collectors become inadequate.
The main (and only) recipient of all wastewater and stormwater runoff is the Neretva River. Neretva divides the wastewater system into 2 completely independent parts: the left (East) and right (West) bank. Neither the right nor the left of the neretva has a unified wastewater system.
4. Planning and design criteria The establishment of basic planning and design criteria and the subsequent projection of population and wastewater services requirements are crucial to the formation of a proper Urban Environment and Water Quality Plan for the City of Mostar. The following general planning criteria formed basis for development of a recommended plan: ● Planning period; • Service area; • Level of service; • Planned economic and industrial activities; • Water quality objectives; • Current regulations; • International criteria; • Planning ranges; • Population projections; • Wastewater flow and strenght.
To plan the required physical components of wastewater system to meet the projected wastewater discharges, the following component design criteria were established for use: • Collection systems; • Pumping stations; • Wastewater treatment.
5. Alternative Identifications and Evaluation Alternative wastewater system layouts were developed based on the water quality and quantity projections and other planning criteria. The service area can be divided into 3 service sub-areas: • North Valley; • Central Valley; • South Valley. These sub-areas were used to formulate 3 main alternative wastewater management system. Within some of these maim options several sub-options also were identified that dealt with alternate conveyance systems.
The alternatives identified and previously described were evaluated using various criteria: a) Monetary Factors: • Relative Cost b) Non-Monetary Factors: ►Performance: • Sensitivity to raw wastewater characteristics; • Compliance with effluent discharge requirements/water quality ovjectives; • Compatibility with and maximum utilization of existing wastewater collection system; • Technical feasibility; • Acceptability/complexity of proposed technology; • Construction considerations; • System reliability/flexibility; and • O&M considerations.
►Environmental related: • Odor generation potential; • Noise; • Short-term construction impacts; • Biological community impacts; • Community impacts and resettlements issues; and • Aesthetics. ►Other: • Land availability; • Adaptation to phased implementation; • Future expansion potential; and • Stakeholder acceptability.
6. Overall Plan Description As a result of the above analysis and recommendations, the selected plan consists of the following elements : • Install a wastewater treatment system for the northern valley, using a natural treatment technology as land permits; individual septic systems may be required for certain isolated users; • Install a dual collector system in the Central Valley area, one interceptor sewer on each side of the river with an inverted siphon to transport all flow to one side of the river; • Install a mechanical-biological WWTP for the Central Valley Service Area; • Install a wastewater treatment system for the southern valley using natural treatment technology or an oxidation ditch system, as land permits; individual septic systems may be required for certain isolated users; • A main raw wastewater pump station is required to lift wastewater to each wastewater treatment system, the costs of which are included with the treatment olant costs; • Local collection system will be installed within the community; approximately 13 small local pumping stations (8 on the left bank and 5 on the right bank) will be required for lifting wastewater from some low-lying areas near the river up to the collection system.
The capital cost for the overall recommended plan, for collection and treatment of the anticipated year 2032 flows and loads, is US$ 83.430.000. The annual O&M cost estimated for the selected alternative is US$ 3.226.000. These costs include wastewater collection, pumping and treatment in each of 3 service areas. The cost estimates should be updated as the project components are better defined during the design phases of the project. Currency conversion of1 Euro = 2 KM = US$ 1,20.
7. Environmental Impact Assessment and Mitigation on the Recommneded PLan Propsed option 3A was evaluated according to potential impacts on the following resources: • Water, • Wildlife habitat and sensitive natural areas, • Threatened and endangered species, • Energy, • Noise, • Socio-economic environment, • Cultural resources, • Air quality.
