Groundwater sources in Thailand are being contaminated due to poor selection of waste sites. "Studies point out that the dumpsites lack rock barriers that prevent contaminants from leaching,' said Cherdpong Siriwit, director of the country's mineral resources department. An old dumpsite at the Mae Hia area in Chiang Mai is a classic example. "Surveys to determine suitable sites have never been conducted. Therefore, many sites violate geological standards,' said geologist Worawoot Tantiwanit. He believes that the problem can be avoided by conducting environmental impact assessments of potential sites beforehand.