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Evaluation & Design of Open Loop Geothermal System

Advantage Engineers evaluated site conditions to determine if an open loop geothermal system was feasible at a Lancaster, PA site. The local historical society in Lancaster Township planned an expansion of their facility to house it's archives. The originally designed closed-loop geothermal well for the structure encountered cavernous limestone and therefore the historical society faced cost overruns for additional well casing and water disposal. The construction management firm engaged by the historical society brought on Advantage Engineers to evaluate site conditions to determine if an open loop geothermal system, with a demand for groundwater flow rate of 80 to 160 gallons per minutes, was feasible in terms of water quantity and quality. Following our reconnaissance, testing, and evaluation, it was concluded that an open loop geothermal system was appropriate.

To complete our investigation, testing, and evaluation, Advantage Engineers performed the following:

  • Supervised the drilling and testing of new open loop geothermal wells
  • Performed geologic logging and groundwater monitoring to identify major water producing zones and gage initial water quality
  • Aquifer discharge test to determine well yield sustainability and evaluate aquifer conditions
  • Aquifer injection test to simulate operation of the closed loop system, and evaluate absorption and dissipation, and to determine if long-term operation could result in groundwater mounding
  • Chemical analysis to model inorganic parameters and the potential for mineral build-up and scaling on heat exchange equipment

Advantage's technical report included recommendations for:

  • Sizing of well pumps
  • Variable frequency pumps
  • Parameters for normal and peak load operation
  • Additional wells
  • Water chemistry and potential for mineralization
  • Seasonal operation to benefit thermal storage within the aquifer

Local historical society in Lancaster Township

Lancaster, PA

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