Assessment of Drawdown Surrounding a Newly Constructed Plaza in Hummels Wharf, PA by means of Groundwater Monitoring and Modeling

Monroe Marketplace, a new 750,000 ft2 mall plaza, built in Hummels Wharf, PA, is using a high-rate pumping well that may lower the local water table has caused concern among local residents. The objective of the study is to determine whether or not two onsite pumping well will cause a cone of depression that will drain the domestic wells in the surrounding residential area. To study the effect of pumpage, several domestic wells around the location of the pumping wells were selected and monitored beginning March 2008. Some wells have shown a 20 feet drop already. A geological cross-section was constructed and the local hydrology was investigated. The groundwater flow is mostly controlled by the joints and fractures within the unconfined aquifer made of Keyser and Tonoloway formations. A conceptual model was created based on initial parameters and boundary conditions using GMS 7.0 and several scenarios were tested for suitable hydraulic conductivity matching the most realistic scenario comparable to real conditions. The results of the Model, the measured data and Neuman & Witherspoon equation applied to the unconfined aquifer have shown comparable results. The pumping wells have had varying impacts on the residential wells at the present time and the two cones of depression show a potential effect especially on one of the wells.