BCAB #1662 - Backflow Prevention, Article 126.96.36.199. (1998 BCBC)
September 16, 2009
Re: Backflow Prevention, Article 188.8.131.52. (1998 BCBC)
The project is a new Part 3 multi-use development with two residential towers and commercial occupancies on the lower levels. The development includes a tank below the mechanical room for storage of storm water to be used for landscape irrigation and as a heat sink for the heat pump system. Pipes for the irrigation system run within the building to above ground patios and the roof.
Reason for Appeal
Subsection 7.6.2. of the 1998 BC Building Code requires potable water systems to be protected from contamination. Sentence 184.108.40.206.(1) is an overall provision requiring connections to potable water systems to be designed and installed to prevent contamination. Sentence 220.127.116.11.(2) requires backflow preventers to be selected and installed in conformance with CAN/CSA-B64.10-M88, “Manual for the Selection and Installation of Backflow Prevention Devices.” Articles 18.104.22.168. and 22.214.171.124. have specific provisions to protect the potable water system from contamination caused by back-siphonage and back pressure respectively. In addition to the foregoing, Article 126.96.36.199. requires premise or zone isolation through installation of a reduced pressure principle backflow preventer where a “severe health hazard” may result from backflow.
The appellant contends that there is only a moderate health hazard posed by a potential backflow and has designed the system accordingly. The appellant’s position is that they have satisfied the requirements of the BCBC and CSA B64.10 standard by providing a double check valve backflow preventer on the cold water supply to the building (premise isolation) due to the moderate hazard assessed.
Building Official's Position
The building official maintains that the potential health hazard should be classified as severe because of the potential interconnection of the independently pressurized non-potable irrigation system and the potable water system where back-siphonage and/or back pressure could contaminate the potable water system. A severe hazard rating requires premise isolation with a reduced pressure backflow assembly.
Appeal Board Decision #1662
Based on review of the 1998 BCBC and referenced edition of CSA-B64.10 it is the determination of the Board that the stormwater retention and irrigation system constitutes a severe health hazard because of potential cross-connection involving substances that could be a danger to health. Therefore, premise isolation must be provided by a reduced pressure principle backflow
George Humphrey, Chair