Client project details
Merrimack Village District, NH (Groundwater Protection)
EGGI Monitors Groundwater Quality Associated with the Blasting and Construction of the Largest Shopping Mall in New Hampshire to Protect Existing Public Drinking Water Supplies
On behalf of the Town of Merrimack and the Merrimack Village District (MVD), EGGI oversaw a groundwater quality protection program for one of the largest blasting projects in the State of New Hampshire. Construction of the Merrimack Premium Outlet Mall required the blasting of nearly 1 million cubic yards of rock, which is equivalent to the largest rock quarry activity in the State of New Hampshire. A significant portion of the blast zone was located within the Wellhead Protection Area (WHPA) for one of the highest-yielding public water supply wells operated by the Merrimack Village Water District. (This well yields 1.2 MGD.) Protecting the quality and quantity of the groundwater resources produced from this well during blasting was imperative.
As the Town’s consultant, EGGI ensured that the developer had prepared and followed a detailed blasting plan that was based on the best available science and leading industry practice. To monitor the effectiveness of the blasting plan, EGGI developed and oversaw the execution of a comprehensive groundwater and surface water monitoring program involving monthly groundwater sample collection from a network of onsite wells and surface water bodies. Sampling began prior to the start of blasting to establish baseline chemistry of the local aquifer, and continued on a monthly basis throughout the construction period.
Hundreds of water quality samples were collected at the project site. Although elevated nitrate levels associated with the blasting activities did occur at a select few sites, blasting activities could be properly managed such that the nitrate did not cause diminishment in groundwater quality at, or near, the MVD Production Well. EGGI continues to monitor water quality collected by the developer on a regular basis.
As the Town’s consultant, EGGI ensured that the developer had prepared and followed a detailed blasting plan that was based on the best available science and leading industry practice."