Protection of Karst Springs Used for Water Supply in Istria by Building Sewage Systems for Small Rural Settlements

Abstract

Wastewater drainage for 6.762 settlements in the Republic of Croatia is grouped in 736 agglomerations, of which 468 agglomerations have loads of up to 2.000 population eqivalent (PE). Although the requirements of the Urban Wastewater Treatment Directive apply to agglomerations of more than 2.000 PE, it is necessary to adequately dispose wastewater of these smaller agglomerations, particularly in sensitive areas such as drinking water protection zones. In order to protect drinking water sources in the Istrian County, the study "Organization, construction and maintenance of drainage and wastewater treatment systems for small settlements in drinking water protection areas of the Istrian County" was prepared and the Istrian Water Protection System Ltd., whose task is the realization of the above mentioned Study, was established. The Study included 173 settlements in the areas of drinking water protection zones, where about 38.000 inhabitants live. This paper presents the designs of two wastewater drainage systems for small settlements in Istria, which were developed within two graduation theses: for the settlement Loborika and for settlements Rapavel, Anžići and Smolići. The aim of this paper is to highlight the problem of drinking water sources protection in karst areas, the possibility of protection by construction of appropriate sewage systems and wastewater treatment plants, problems encountered in the design of separate systems for agglomerations less than 2.000 PE as well as problems that can be expected in the future when these systems will be in use.