BCAB #1623 - Water Pipe Sizing, Sentences 7.6.1.1.(1), Article 7.6.3.4., P-7.6.3.1.(1)

May 24, 2006

BCAB #1623

Re: Water Pipe Sizing, Sentences 7.6.1.1.(1), Article 7.6.3.4., P-7.6.3.1.(1)

Project Description

The subject is a bare land strata development, consisting of six bare land strata residential lots with the lot frontages along a private roadway (being common strata property). A 2” diameter PVC water line connects to a municipal water main near the entrance of the development, and extends approximately 57 metres along (and under) the private roadway. Along its length, there are six ¾” connections to serve the individual residential lots.  The water pressure at the public water main is 503 kPa.

Reason for Appeal

Sentence 7.6.1.1.(1) states that potable water systems shall be designed in accordance with good engineering practice such as described in ASHRAE Guide and Data Books, the AHREA Handbooks and ASPE Data books.  P-7.6.6.1. indicates an alternative procedure to determine water pipe sizing. For the purpose of using the alternative method for sizing a water service pipe described in P-7.6.6.1., the Code indicates to “select the “length column” which is equal or longer than the required length of service pipe.”

The Code defines a water service pipe as a pipe that conveys water from a public water main or private water source to the inside of the building.

Appellant’s Position

The appellant contends it is appropriate to design the 57 m of pipe in the roadway, connected to the municipal water main using Table P-7.6.1. The designer uses 57 meters for the service pipe length. The designer then uses Table 7.6.3.4. to determine the pipe size from the roadway pipe to the building using the appropriate hydraulic load limitations.

Building Official's Position

The Building Official does not consider it appropriate that different portions of a water distribution system be designed using different methods.

The Building Official considers that by definition, the water service pipe is measured from the connection at the municipal water main to the most remote entrance into a building, and not the 57 m length under the road used by the designer. The Building Official also contends that when using Table P-7.6.1. the developed length which should be used is the length from the municipal water main to the most remote outlet of the furthest dwelling unit which would correspond to 50-60 more meters for a total of 110 meters depending on the number of stories the dwelling may contain.

Appeal Board Decision #1623

Sentence 7.6.1.1.(1) relies upon the application of good engineering practice for the design of potable water systems. It is the determination of the Board that this does not preclude the use of a combination of design standards provided the overall design complies with good engineering practice.

George Humphrey, Chair