2007 Ground Water Summit

Wednesday, May 2, 2007 : 8:40 a.m.

Real-time Measurement and Assessment of Quarry Dewatering Effects

William Y. Potter, P.G., Louis F. Vittorio Jr., M.S., P.G. and Matthew S. Weikel, M.S., EarthRes Group Inc.

Assessments of quarry dewatering in fractured bedrock aquifers are typically performed using calibrated numerical models that are supported with site-specific aquifer test data.  Uncertainty in the predicted cone of depression may remain due to the scope of investigation, variance of aquifer parameters with depth, the distribution and scale of fractures, and seasonal variations.  In the current study, a large-scale quarry dewatering test was performed on an existing quarry in a karst watershed.  The test was performed to stress the system and measure aquifer and stream response to real time large scale dewatering.  To accomplish the test, water outflow from the quarry was held below inflow, allowing the water level in the quarry to rise 40 feet.  The water level in the quarry was held constant at this level over a period of 14 days to allow surrounding aquifer equilibration.  The water level was then lowered over 40 feet during a 22 day period of aggressive pumping at an average rate of approximately 2,770 GPM or approximately 4 million gallons a day.  Upon completion of the drawdown phase, the water level in the quarry was held constantly depressed for 16 days.  The quarry was then permitted to fill naturally via ground water and surface water inflow over an approximate 36 day period.  Approximately four months of water level measurements were collected from a monitoring network of approximately 65 wells, 30 of which were equipped with electronic pressure transducers.  Additional data collection included basin specific precipitation, stream flow and stage at three locations, and quarry discharge volumes.  Data collected from the test were analyzed to determine the direct effects of quarry dewatering, providing the basis for sound water management and to determine the availability of water resources for basin stakeholders. 

William Y. Potter, P.G., EarthRes Group Inc. William Potter is a Senior Geologist and Project Manager at EarthRes Group, Inc. and has more than eighteen years of experience in environmental consulting and geophysical data processing. He holds a Degree in Geology from Ohio Wesleyan University. Mr. Potter is a registered Professional Geologist in Pennsylvania, a New Jersey Certified Subsurface Evaluator and is a member of the Pennsylvania Council of Professional Geologists. His areas of specialization include mineral resource permitting, quarry dewatering analysis, fractured rock/karst aquifer system characterization, and groundwater flow evaluation. Mr. Potter has also worked extensively in the solid waste industry and in conducting environmental investigation.

Louis F. Vittorio Jr., M.S., P.G., EarthRes Group Inc. Mr. Vittorio is the Vice President and Principal Hydrogeologist at ERG and has more than twenty-two years of experience in environmental consulting. He holds a BS Degree in Geology/Geophysics from the University of Pittsburgh and an MS Degree in Geology from Lehigh University. Mr. Vittorio is a registered Professional Geologist in Pennsylvania, a NJ Certified Subsurface Evaluator and is a member of the Pennsylvania Council of Professional Geologists, American Water Works Association and NGWA. Specialized project areas include water and mineral resource permitting, quarry dewatering analysis, fractured rock/karst aquifer system characterization, and groundwater flow and contaminant transport modeling.

Matthew S. Weikel, M.S., EarthRes Group Inc. Mr. Weikel is a Project Scientist at ERG and has 3 years of experience in environmental consulting. He holds BS and MS Degrees in Geology from Temple University. Mr. Weikel is a member of the Geological Society of America and the Environmental Engineering Geophysical Society. Specialized project areas include water and mineral resource permitting, quarry dewatering analysis, fractured rock/karst aquifer system characterization, and groundwater flow and contaminant transport modeling.


The 2007 Ground Water Summit