Limiting Water Quality Impacts Due to Large Scale Blasting

Thursday, September 26, 2013: 10:30 a.m.
Charles Crocetti, PhD, PG , Sanborn, Head & Associates, Inc., Concord, NH

We will present concepts regarding design of rock blasting programs for construction, with the goal of limiting blasting-related water quality impacts. The 160-acre site is one of the largest private construction projects in northern New England in the last decade, and included the use of 900 tons of blasting agents to remove approximately 1 million cubic yards of rock. From the permitting phase through construction (2007 to present), Sanborn Head has been the lead consultant on development, implementation, and oversight of blasting and water quality monitoring programs.

Municipal officials were very concerned about the potential impact to the town’s water supply wellfield located 3000 feet away from the site, given the project’s magnitude. These concerns were further heightened due to several highly publicized incidents of blasting impacts to drinking water wells in southern New Hampshire over the past five years. Because of the level of concern about the proposed blasting, a blasting and water quality monitoring program, which we believe is one of the most rigorous in the country to date, was developed and implemented in concert with the town and its hydrogeological consultant. The water quality monitoring program included pre-construction monitoring and monthly monitoring, for approximately 24 months of construction, of 17 monitoring wells and five surface water locations for a broad list of parameters. Semi-annual monitoring for up to five years after construction is ongoing.

With blasting completed in November 2011, as of the date of this abstract only very limited exceedances of the project groundwater or surface water quality criteria potentially attributable to blasting have been observed at the site. These were limited to short-term nitrate exceedances in the vicinity of a blasting “misfire,” and the observed nitrate concentrations quickly returned to within project water quality criteria.

Charles Crocetti, PhD, PG, Sanborn, Head & Associates, Inc., Concord, NH
Charles Crocetti is a senior vice president and cofounder of Sanborn, Head & Associates, with more than 25 years of experience in hydrogeological, environmental, and remedial projects, in over 20 states and internationally. His particular expertise is the application of geochemistry to hydrogeological and environmental issues. Recent interests include assessment and control of impacts to groundwater due to blasting; emerging contaminant 1,4-dioxane; and geologic and geochemical influences on the success of geothermal/ground source heat pump systems. He earned a B.A. from Dartmouth College in earth sciences and an M.S. and doctorate in geological sciences from Harvard University.