Fort Drum Installation

Watertown, NY

Water Supply Well Capture Zones

Source Water
Protection Planning

Client: United States Army Corps of Engineers, Baltimore District for the New York District

ARM performed Source Water Protection Planning (SWPP) for this military installation prior to a significant site expansion. Various areas of anticipated expansion are situated adjacent to the public water supply wellfield for the base, which consists of 10 wells located in and around the base airfield. ARM performed the SWPP consistent with federal EPA guidelines for source water protection planning and with the New York Wellhead Protection Program. ARM initially performed a comprehensive review of published geologic and hydrogeologic reports of the Fort Drum area to understand the physical setting of the subject area; wellfield performance information and data were also compiled and evaluated to determine wellfield operations, water demands, and well performance. Review of available information indicated that two aquifer systems were used to withdrawal groundwater at the base: a shallow glacial overburden aquifer and a deeper fractured bedrock aquifer. As part of the planning, ARM conducted a constant rate pumping test at one deep bedrock water supply well to acquire aquifer parameters of the deep fractured bedrock system. ARM installed a bedrock piezometers to a depth of 165 feet to be used as a bedrock observation point during the pumping test.

Utilizing data from the pumping test and existing aquifer and well data, ARM delineated two different recharge or capture zones for each water supply well in the overburden and bedrock aquifers at the base. ARM determined two types of wellhead protection areas for each well: 1) Remedial Action Areas (RAAs) situated within a 60-day travel time for contaminants to reach the wells and 2) capture zones in which a 5-year travel time is required for potential contaminant impact. The site-specific wellhead protection areas were compared to the general New York-designated areas and the largest areas were selected as the recommended wellhead protection areas for the various wells. The USEPA WhAEM analytical element model was used as a tool to define the groundwater capture zones. This model was also used to determine optimum sustainable pumping rates for each of the wells, with attention to preventing the intake of potentially impacted groundwater. Other planning activities included conducting a contaminant inventory of the wellfield area and the development of wellhead management considerations to help protect groundwater at the base. The wellhead management concepts to ensure satisfactory groundwater quality included use of wellhead protection areas, contaminant source reduction, water withdrawal controls, inspection and monitoring program, engineering design and maintenance, land use controls, contingency planning, and evaluation of new groundwater sources. A project report containing the information discussed above was prepared by ARM and submitted to Fort Drum DPW.

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