E1592 V 5 Public Disclosure Authorized OGULIN SEWERAGE SYSTEM & WASTE WATER TREATMENT WORKS Public Disclosure Authorized ENVIRONMENTAL IMPACT STUDY (UPDATED) Public Disclosure Authorized Public Disclosure Authorized Oikon Ltd Parsons Brinckerhoff Vlade Prekrata 20 Parnell House 1000 Zagreb Croatia Environmental Impact Study of the Ogulin Sewerage System 25 Wilton Road London SW1V 1LW June 2005 2 Environmental Impact Study of the Ogulin Sewerage System 1 INTRODUCTION ......................................................................................................................................... 2 1.1 OVERVIEW ................................................................................................................................................. 2 1.2 THE PROPOSED PROJECT............................................................................................................................ 2 1.3 PROJECT PROPONENT................................................................................................................................. 7 1.4 APPROACH TO THE EIA.............................................................................................................................. 7 1.5 STRUCTURE OF THE ENVIRONMENTAL STATEMENT .................................................................................. 8 2 LEGISLATIVE AND PLANNING CONTEXT FOR THE EIA .............................................................. 9 2.1 INTERNATIONAL CONVENTIONS, PROTOCOLS AND COMMITMENTS........................................................... 9 2.2 NATIONAL LEGISLATIVE REQUIREMENTS ................................................................................................ 10 2.3 PHYSICAL PLANNING DOCUMENTS .......................................................................................................... 11 2.4 PROTECTED NATURAL, URBAN AND RURAL VALUES.............................................................................. 12 3 EXISTING CONDITIONS......................................................................................................................... 14 3.1 SITE LOCATION........................................................................................................................................ 14 3.2 SURFACE DRAINAGE................................................................................................................................ 14 3.3 GEOLOGY AND SOILS............................................................................................................................... 19 3.4 HYDROGEOLOGY ..................................................................................................................................... 23 3.5 CLIMATE AND METEOROLOGY................................................................................................................. 36 3.6 SOCIO-ECONOMICS................................................................................................................................... 39 3.7 TRAFFIC ................................................................................................................................................... 39 3.8 ECOLOGY AND NATURE CONSERVATION................................................................................................. 40 4 PROJECT DESCRIPTION........................................................................................................................ 44 4.1 OVERVIEW ............................................................................................................................................... 44 4.2 NEED FOR THE PROJECT........................................................................................................................... 44 4.3 THE PROPOSED SEWERAGE SYSTEM ........................................................................................................ 45 4.4 THE WASTE WATER TREATMENT PLANT................................................................................................. 49 4.5 RECEIVING WATERS ................................................................................................................................ 56 4.6 ANALYSIS OF ALTERNATIVES .................................................................................................................. 56 5 IMPACT ASSESSMENT AND MITIGATION ....................................................................................... 62 5.1 INTRODUCTION ........................................................................................................................................ 62 5.2 THE SEWAGE NETWORK .......................................................................................................................... 62 5.3 THE WASTE WATER TREATMENT PLANT................................................................................................. 63 5.4 IMPACTS DURING DECOMMISSIONING...................................................................................................... 67 5.5 IMPACTS DURING ABNORMAL OPERATION .............................................................................................. 67 6 ENVIRONMENTAL MONITORING, MANAGEMENT AND CONSULTATION............................ 69 6.1 OVERVIEW ............................................................................................................................................... 69 6.2 SURFACE WATERS .................................................................................................................................... 69 6.3 GROUNDWATERS ..................................................................................................................................... 69 6.4 SLUDGE QUALITY .................................................................................................................................... 71 6.5 AIR QUALITY ........................................................................................................................................... 71 6.6 NOISE....................................................................................................................................................... 71 6.7 ENVIRONMENTAL POLICIES ..................................................................................................................... 72 6.8 PUBLIC CONSULTATION ........................................................................................................................... 72 7 LEGISLATIVE REFERENCES................................................................................................................ 74 1 Environmental Impact Study of the Ogulin Sewerage System Introduction Overview Ogulin is a market town located in northern Croatia (see Figure 1.1, 1.2 and 1.3 for location). The town has long-held problems of wastewater and stormwater treatment and disposal. At present the majority of the households collect wastewater on their own and discharge it without prior treatment into septic tanks (“black pits”) or directly into the nearby sinkholes or abysses, where it enters the local groundwaters. The situation with stormwater drainage is the same, and the increase in hard surfaces that has accompanied urbanisation has resulted in not only a considerable increase in the flow of stormwaters, but also in their pollution, with heavy precipitation commonly resulting in clogging and local flooding, which in turn have impacts on hygiene, ecology and economy. The Proposed Project Project Location Ogulin town is located in the Ogulin-Plaški valley, a hilly area some 300 m above sea level, and rising to 500-600 m in higher elevations (see Figure 1.3). The valley is comprised of two karst fields, the Ogulin and Plaški Fields, made of highly pervious layers of limestone and dolomite with occasional impervious Triassic layers. The karst area is characterized by long cave systems such as ula’s Precipice- Medvednica Cave, etc. Figure 1.2 Ogulin Town Setting 2 Environmental Impact Study of the Ogulin Sewerage System This area is considered sensitive since local pollution can have grave consequences on a wide area and the construction of a drainage system has therefore been set as one of the priorities of the town of Ogulin and conceptual designs for the sewerage system and the wastewater treatment plant were first developed in 1989. It was decided to form the combined sewerage system in the town, i.e. the system of transporting household and industrial wastewaters together with precipitation waters through the same (common) collectors. The idea was that wastewater will first be treated and then discharged into the underground on the territory of Galga, to the north of the settlement of Otok Oštarijski. 3 Environmental Impact Study of the Ogulin Sewerage System Figure 1.1. Location Map for Ogulin Town 4 Environmental Impact Study of the Ogulin Sewerage System Figure 1.3 The Ogulin Region 5 Environmental Impact Study of the Ogulin Sewerage System Project Concept The proposed project provides for the construction of a partly combined system with a network of sewers which would receive both household and industrial wastewater, with stormwaters collected from those (mostly traffic) surfaces where they could cause traffic difficulties or endanger the town in some other way. The need for such a sewerage system is determined by a number of factors, including the current number of inhabitants, the quality and composition of wastewater, and ecologic and sanitary requirements.