Middlesex Township Municipal Authority

Cumberland County, PA

Pre-Drilling Plan

Groundwater Availability Study

Client: Middlesex Township Management Authority

Middlesex Township Municipal Authority engaged ARM in March 1999 to evaluate the groundwater development potential of the southern half of the township. The investigation was the first step of a multi-year program to develop approximately three million gallons per day (MGD) of groundwater to replace the public water supply currently obtained from a neighboring municipality. ARM conducted a comprehensive hydrogeologic investigation of this ten square mile study area to determine the quantity and quality of groundwater available from the bedrock aquifers of the township. The water budget indicated that approximately 7.5 MGD was potentially available, and that the groundwater quality was good to excellent. Consideration was also given to reserving sufficient groundwater baseflow discharge to the Letort Spring Run, a sensitive, cold-water trout stream located in the extreme northern portion of the study area.

Following the initial hydrogeologic mapping (aquifer delineation) and water budget analysis, ARM performed fracture trace analysis to identify zones of concentrated fracturing within the most significant carbonate (limestone and dolomite) bedrock units of the township. Intersections of these fracture traces were interpreted as having the highest potential for well drilling. This approach resulted in the selection of 30 well sites that were then subjected to field inspection for confirmation purposes. Based on these field inspections, 20 well sites were selected and ranked according to well yield potential. From this, priorities for test drilling were established, with factors such as proximity to the existing water distribution system, planned growth areas, roads, and property ownership given appropriate weightings for final well site ranking. On the basis of this work, a final project report was prepared entitled “Groundwater Availability and Well Siting Study.” With this completed, Middlesex Township proceeded with acquisition of two well sites, and completed test well drilling and reconstruction of Well 1 in winter 2004. The groundwater yield from one of these wells exceeds 1.5 MGD, and should provide a large fraction of the Authority’s water demands for the next 25 years.

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