Understanding ground properties and geoexchange borehole construction
By Denis Tanguay
By Denis Tanguay
In early 2007, the Canadian GeoExchange Coalition (CGC), Canada’s
national industry association for ground source heat pump technology,
deployed a comprehensive market transformation initiative to help the
industry grow in a sustainable and professional manner.
In early 2007, the Canadian GeoExchange Coalition (CGC), Canada’s national industry association for ground source heat pump technology, deployed a comprehensive market transformation initiative to help the industry grow in a sustainable and professional manner. Over the past three years, and after reviewing and certifying over 10,000 residential geoexchange systems, CGC personnel and accredited professionals identified several anomalies and weaknesses in the codes, standards and regulations affecting the geothermal industry in Canada.
Industry stakeholders also identified important regulatory omissions that slow down and sometimes completely block the introduction of new technologies into the marketplace. At the same time, officials from regulatory organizations and other public-sector parties, notably municipalities, are concerned about following the existing codes, standards and regulations.
In this context, and as part of its market transformation initiative and its efforts to consolidate the industry in Canada, the CGC organized a national consultation in June 2009 dealing with the regulatory issues affecting the geothermal industry in Canada. A total of seven intensive workshops were offered. CGC-accredited professionals and other industry players, municipal and provincial government representatives in particular, participated in these workshops. These sessions took place in Burnaby, Calgary, Regina, Toronto, Saint-Hyacinthe, Quebec City and Truro.
Participants in the workshops were invited to identify problems concerning technical and regulatory issues, with the ultimate goal of formulating suggestions concerning improvements to the codes, standards and regulations, as well as recommendations for improving the CGC’s Global Quality GeoExchange Program.
Three themes had previously been identified by the CGC in order to guide the discussions: (1) equipment, (2) practices relating to system design, and (3) the technologies. These themes were then subdivided into several sections in order to provide depth in the discussions. These oriented discussions were supported by open questions on the various subjects identified. In order to cover the widest possible range of issues, the final part of the workshops was devoted to open discussions, either to conclude the debates on issues previously raised or to identify new subjects and discuss them.
A fairly significant number of comments and discussions related to the geoexchange borehole construction, with a major focus on technical issues related to geology as well as proper grouting procedures and loop installations. Many recommendations were formulated during the meetings and one of them, for example, specifically called for the CGC to develop and distribute a technical document that explains in depth, yet in simple terms, the thermal properties of soils. Many other discussions emphasized the need for standardized training for loop installers, particularly on large commercial projects.
To address these concerns raised by the industry and the regulatory authorities, the CGC contracted specialists on both the academic and industry sides to develop the appropriate courses, training material and technical documentation.
The first set of training material was developed for design professionals (engineers, architects, technicians) who work in the geoexchange industry but who do not necessarily have basic knowledge of geology. After taking this course, participants will know how to find appropriate field data and information and how to interpret it. The training touches topics such as the evaluation of ground temperature, identification of geological formation (rock and soil) and their thermal properties, the impact assessment of ground water, as well as compiling and understanding a drilling report. This training will be available in May 2010 and the duration should be limited to a one-day session.
The second training program focuses on loop installation in all types of conditions: horizontal, vertical and directional as well as open loops. It is intended for loop installers working for geotechnical and ground water drilling companies, installation contractors and other companies qualified for the installation of geoexchange systems.
With a brief introduction to the geoexchange technology, the core of this course focuses on topics such as drilling types, borehole construction, borehole sealing, horizontal trenching, connecting the underground pipe network to the building, communication with system installer and designer as well as appropriate workmanship and technical installation reporting such as the CGC geoexchange borehole report.
The course ends with a review of applicable legislations and regulations as well as an understanding of the C-448 installation standard. This specialized course is scheduled to be delivered over two full days and is intensely supported by visual training material. The first sessions will be scheduled for May 2010.
Both courses will become components of the CGC Global Quality GeoExchange Program. To learn more about these training initiatives, please visit the CGC website at www.geoexchange.ca
Finally, CGC is pleased to announce the publication of a 385-page technical manual that comprehensively addresses geoexchange fundamentals, installation, and design issues in a Canadian context and from a college perspective. This textbook is the result of more than five years of efforts by industry specialists, college instructors, technical writers and CGC staff. n
President & CEO Canadian GeoExchange Coalition