Groundwater Modeling for ODNR IM Permits

Groundwater Modeling for ODNR IM Permits

For the Aggregates and Industrial Minerals Industry

Aggregate operations commonly require quarry or sand and gravel pit dewatering as part of the resource extraction process; this activity is regulated by Ohio Administrative Code (OAC) 1501:14-5-01 via the Ohio Department of Natural Resources. Quarries that extract industrial minerals from below the water table must include a groundwater modeling report with an application for an Industrial Minerals (IM) surface permit.  Sand and gravel operations utilizing suction dredge and/or clamshell equipment return the extracted water back to the mining area, so groundwater modeling is not indicated in these cases.  If, however, a sand and gravel producer needs to lower the water level in the pit because of equipment (reach) limitations, a groundwater model report will be requested during the application process. 

Groundwater flow model information is required with each new request (application) for an IM permit.  If an operation is expanded, experiences unforeseen impacts to the water levels or the permit is otherwise modified, the model may be required to be revised.  Furthermore, a new model may be required at the time of renewal (permit term is 15 years), especially if ODNR believes that the initial model no longer applies to the operation. 

The most common consideration of the impact that dewatering may have on the environment is the drawdown of the groundwater table below neighboring properties and in the general area of the mine.  However, safety implications in large and deep open pits can be addressed by modelling the hydraulic pore pressure build-up and the possibility / eventuality of slope failure. Numerical groundwater flow models also can be used for operational purposes by identifying the optimal location and pumping schedule for dewatering apparatus and to assess the performance of alternate dewatering methods.

At the current time, approximately 80% of all groundwater modeling performed in conjunction with IM permit application process is performed by consultants.  An incomplete or inaccurate model report will be, at best, returned to the permittee for clarification or, at worst, rejected.  While outright rejection is not typical, many IM permit applications become stalled during review due to problems with the groundwater modeling report.  BMI has identified some of the more common oversights

or issues encountered during groundwater modeling and reporting.

  1. Incomplete Narrative in Report

    OAC specifies the information required to be described in the text.  That information includes, but is not limited to:

    • background and historic information about the site, operator, permit number and boundaries and reason for dewatering,
    • hydrogeologic setting including surface water, geology (soil and bedrock) and aquifer characteristics,

    • water supply inventory discussion based on water well logs and water withdrawal facilities,

    • conceptual design for groundwater model used, often missing criteria and rationale, model grid and layers, and consideration of boundary conditions,

    • calibration settings, criteria and hydraulic parameters and

    • discussion of model results for each scenario simulated


  2. Incomplete Mapping

Each map is required to show ten (10) items prescribed by ODNR.

Individual maps are required for the mining site with general information, hydrogeologic setting, location of area wells and water withdrawal facilities, potentiometric surface, hydrogeologic cross sections, and hydrology map.

  1. Incomplete or Inaccurate Modelling

Frequently identified oversights include:

  • failure to use finite difference modeling software,

  • use of wrong model state (transient or steady state),

  • boundary condition assignment that does not accurately represent the site

  • model calibration information

  • modelling output, including maps and charts

Bowser-Morner, Inc. (BMI) Environmental Team has superior capabilities for creating a well-considered groundwater model. 

Led by hydrogeologist and modelling expert Jeff Arp, our team of experienced geologists and environmental specialists bring over 100 years to the table.  The environmental team isn’t just “book-educated” about the aggregate industry – BMI employs personnel who formerly worked for the aggregate industry, have walked the walk and truly understand the industry.  Our decades-long relationships with producer foremen, geologists, mining engineers and other decision makers allow BMI to communicate easily and effectively during the modeling process.

BMI’s often-awarded construction materials testing laboratory is a huge repository of aggregate physical and chemical testing data.  BMI will utilize a producer’s existing data, or can test current soil and bedrock samples to provide the specific data needed as input for the selected model.

Bowser-Morner has a fleet of drones and a team of FAA Part 107 licensed drone pilots, working in tandem with our professional CAD designers, to provide topographic mapping and aerial imagery.  We generate site-wide aerial maps compatible with Google Earth and GIS software that may be useful to the producer for other applications.

BMI creates MODFLOW input files using graphical user interface (GUI) programs to simplify data input and model setup.  These programs include Groundwater Modeling System (GMS), Visual MODFLOW, and ModelMuse.  These programs also include data-output visualization packages that illustrate the model results.

Because the model setup requires a thorough understanding of highly technical issues such as the hydrogeologic setting and model capabilities to develop an accurate simulation, BMI is your best choice to help with your IM permitting and groundwater modeling needs.


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Senior Environmental Specialist View Bio

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