Construction of a project at a proposed site requires understanding of the geological and hydrogeological conditions for the purpose of engineering design and environmental impact assessment. However, investigation and assessment of the site conditions may be challenging for limestone areas due to the irregular occurrence and development of karst. This paper presents a demonstration of the site investigation and assessment for the karst hydrogeological conditions through a case study of a site with complex lithology. A joint on-site surveying and mapping, drilling, geophysical exploration, supplemented by in-situ and laboratory tests, was implemented in the assessment. Results indicate the site area presents a multiplicity in lithology with steep attitude stratum. Northern part of the site distributed shales suffering different degree of weathering, while the rest areas were developed with carbonate rocks. Fracture zones with north-west and north-east trend were developed at the site, which are prone to form strong runoff zone of the groundwater. No shallow buried river, hall-or corridor-type karst caves were detected at the site, neither of large-scale well-connectivity karst channels. However, many small karst and soil caves were developed at the site, which suggest a post treatment of engineering measures for the purpose of engineering and environmental safety. Based on the distribution of karst ratio calculated from boreholes, the proposed site area can be divided into 3 zones of very-strongly developed zone with a karst ratio around 71.2%, strongly developed zone with a ratio around 26.3% and intermediate-slightly developed zone with a ratio of 15.0%. Characteristics of each sub-zones are analyzed regarding to the general layout and later engineering design of the power plant project. This study provides an example of a joint study for site condition assessment at karst areas with complex lithology. Such an assessment is crucial to the site selection, project layout, engineering design and to later environmental impact assessment.
Environmental Impact Assessment of Nuclear Power Plant Accident using Spatial Information Modeling: A Case Study of Chernobyl
