GEOLOGIC MAPPING, HAZARDS AND WATER: VERMONT GEOLOGICAL SURVEY'S IMPACT ON PUBLIC ISSUES

State geological surveys provide data and analysis to address issues such as infrastructure, energy, environmental and human health, and economic development. The Vermont Geological Survey (VGS) provides fundamental geologic maps with a focus on the application of mapping to hazard identification and avoidance and to groundwater quality and quantity. Integration of digital geologic map data with Lidar, bedrock and till geochemistry, and water well data at a regional scale is a goal of current projects in central Vermont.

Slope instability areas, a threat to human health and property, are not adequately identified. Following requests from communities to identify causes and locations of unstable areas, landslide mapping protocols were produced in 2013 for detailed scale maps. In 2015, VGS recognized that mapping at this scale would require 100+ years and initiated Phase 1 mapping by county to identify existing and historic hazard sites within a reasonable time frame, allow towns to develop a set of priorities for detailed work, and promote incorporation of landslide data in town planning processes. Phase 1 integrates surficial mapping and is dramatically improved by Lidar. The third county map will be completed in 2018.

A top priority for VGS is to build useful data sets for: 1) development of water supplies, 2) avoidance and mitigation of groundwater contamination, and 3) response to drought. Data is interpreted at local and statewide scales, with priority mapping areas identified by statewide data analyses and town requests. Maps highlight areas of higher and lower yield, define recharge areas, and are used to interpret the source and transport of elements of concern to human health (ex. arsenic). In 2016, PFOA contamination of groundwater in fractured bedrock was found in Vermont and an intense effort is on-going to map bedrock, glacial deposits, characterize the aquifer, and provide reliable science to assist in reducing exposure to chemical contaminants.