Monitoring of Surface and Ground Water Quality in Geothermal Exploration Drilling of Meshkinshahr Geothermal Field, NW-Iran

Abstract

In this report there are reported results of the monitoring of surface and ground water quality during and after finishing the drilling of three deep geothermal exploration wells in Meshkinshahr geothermal project, NW- Iran. This area has been investigated for geothermal resources by various researchers in the past few years for using geothermal energy to generating electricity. A preliminary review of possible environmental effects of proposed project has been carried out in Environmental Impact Assessment (EIA) project in last few years (Noorollahi and Yousefi, 2003).
During deep geothermal drilling different types of substances like Cement, Bentonite, Barite, Soda ash, Sodium chloride and ect. are used in drilling procedures and cement jobs. A large amount of pollutants may thus be discharged into shallow and deep aquifers and reservoirs that are feeding hot and cold springs and finally discharge into the Khyav River. In this study, an attempt has been made to identify the likely impact of drilling three geothermal exploration wells on Khyav River and several hot and cold springs in a study area about 132 km2. The water quality of Khyav River is very important as it is not only used as the drinking water of Meshkinshahr city but also for the agricultural and aquiculture use of Meshkinshahr city and surrounding communities with a population of 200,000. Monitoring of possible quality change of hot and cold springs in area is very important because the permanent population of two villages (Moeil and Dizo) and many sheep grazer families during summer time use cold springs as a drinking water as well as several tourists that visit the area for site seeing and swimming in hot spots, which may be affected from possible quality change of these springs waters.
The results of study are shown that in during of 18 months monitoring of Khyav River drilling activities have great influence in quality of river and also hot and cold springs, but except some heavy metals, the concentration of all other elements are below drinking water standard levels.