Monitoramento de águas subterrâneas em um empreendimento potencialmente poluidor no município de Santa Maria/RS

Abstract

Growndwater consist of strategic resources essential for public and private water supply. Therefore, the aquifer research by means of groundwater monitoring has been considered very important. In groundwater polluted potential enterprises, a system of monitoring is necessary, because it can not only allow contamination evidences previously, but also provide reference measures in order to portray the aquifer s hydrochemistry and hydrodynamics. The purpose of this study is to establish natural values and temporal variation frequency of groundwater physiochemical and hydrodynamic parameters in the area of a tank fuel in Santa Maria/RS, in an outcrop zone of Guarani Aquifer System (GAS). Therefore, the methodology consisted of: office studies in order to review the literature in the topic; field study, by the hydrogeological monitoring of seven observation wells, during 12 month, topographic work, precipitation measure, hydraulic conductivity assays carried out using the method of excavated piezometer and directly in the wells (infiltration); laboratory study, by analyzing the data statistically using the statistic software SPSS® 13.0 for Windows (2004), development of tridimensional frameworks of groundwater flow and specialization cartograms of physiochemical parameters by using SURFER® 8.0 program. The results showed that the concentration of the physiochemical frameworks studied had temporal alteration in relation to months and seasons, besides variations in the spatial distribution, that indicated differences in the entrance of water in the column of the well, it happened, probably, because of the influence of different layers. It was also possible to observe variations in the water level in the seven monitoring wells from the pluviometric precipitation, indicating that they are situated in an area of GAS direct recharge. Related to the direction of the local groundwater flow, the data obtained showed that in case of fuel leak the river Vacacai-Mirim, 230 m distant of the enterprise, will be affected. In conclusion, the background variation reflects the geologic diversity in the place that has Fluvial Terrace Depository, considered permeable and, the Alemoa member of Santa Maria formation that was considered impermeable. This research contributed to the physiochemical and hydrodynamic characterization in local scale of GAS offering a background, which will subsidize environment organs, supporting in a way to allow possible groundwater contamination evidences previously.