Oral Presentation Australasian Groundwater Conference 2017

Groundwater abstraction, heat exchange and reinjection at the University of Auckland Newmarket Campus Innovation Centre (#221)

James Botting 1 , Alexis Thomas 1
  1. Geotechnical, Beca Limited, Auckland, New Zealand

The University of Auckland has a campus-wide energy use intensity target and wished to utilise natural ventilation systems as much as possible for their new campus in Newmarket. Groundwater in the unconfined fractured basalt aquifer that underlies the project site was identified as a natural renewable resource that could be used as a heat exchange medium for process cooling systems and cooling towers, and reinjected into the same aquifer to enable sustainable use of the resource.

A new bore water system was designed to abstract up to 500 m3/day from an existing water supply well. The feasibility of groundwater reinjection was assessed through 3-Dimensional groundwater modelling, in parallel with injection testing of an existing well further down gradient on site. Injection testing found the existing well to be unsuitable for reinjection and two new reinjection wells were installed. 3-D numerical modelling (using MODFLOW-2005 and SEAWAT v.4)  enabled assessment of the likely magnitude of groundwater drawdown and mounding, under a range of pumping scenarios, as well as the likely extent of thermal plumes generated from reinjection of the heated water. Reinjection commenced in February 2016 following a period of baseline monitoring to assess natural groundwater temperature and level. Data logged by the Building Management System indicates that 6,634 m3 of water was abstracted and 5,420 m3 of water was reinjected in February 2016. Approximately 1,200m3 of water was used for cooling tower makeup water and irrigation, while 38.5MW of heat was rejected from the process cooling systems. City water conservation, as a result of the system is estimated to be up to 15,000 m3 /year with water cost savings of up to $75,000/year.

The groundwater abstraction and reinjection system has been successful in achieving acceptable occupants’ comfort while realising energy and cost savings through sustainable use of the natural groundwater resource.

  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 5 Years or more
  • We are offering awards for Career and Early Career presentations and posters. Please indicate length of time since highest degree completed.: 5 Years or more