Durand, M.; Scott, B.J. 2003 An investigation of geothermal soil gas emissions and indoor air pollution in selected Rotorua buildings . Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 2003/28 36 p.
Abstract: This report presents findings from a preliminary study to assess the affect of soil gas emissions on buildings in Rotorua. The main gases emitted from the Rotorua geothermal field are hydrogen sulphide and carbon dioxide, both of which are denser than air and can be fatal. Studies were undertaken in nine buildings within Rotorua City, which are constructed within the high soil gas anomalies identified by past research. The work began with an initial approach to building occupiers/owners and, where permission was gained, continued with an inspection of the property, documentation of the effects and monitoring of gas concentrations. In most cases occupants knew there was a gas problem and welcomed our activities in exchange for further information. Monitoring equipment included an Environmental Instruments CD98 and a Rae Systems Multi-RAE IR real-time infrared monitors. Eight of the nine buildings we studied were found to have problems with gas ingress. The main means of gas entry were the floors and the sewerage system. Some properties were subject to emissions through floors, walls and ceilings, the gases having penetrated cracks and pore spaces in virtually the entire structure. In some cases gas ingress occurred despite preventative measures having been made during construction or reconstruction, typically the under laying of concrete floors with a butanol seal. Recently constructed buildings (2S exposure, and (c) to better understand and mitigate the disaster potential of higher gas flux in Rotorua. (auth/DG)