BCAB #1235 - Protection from Backflow - Plumbing Code Article 4.6.4.

February 22, 1991

BCAB #1235

Re: Protection from Backflow - Plumbing Code Article 4.6.4.

Project Description

Building drainage system leading to a public sewer system.

Reason for Appeal

Sentence 4.6.4.(2) requires a gate valve or a backwater valve on fixture drains below adjoining street level where there is the possibility of backflow in the public sewer system.

Appellant's Position

The appellant believes the gate valves he has installed are a superior device to control backflow and should be acceptable under Article 4.6.4.

Building Official's Position

The building official maintains that a gate valve is insufficient to protect against a city main surcharging because "it is a little late to go around shutting off the gate valves after the backflow has been discovered." He feels that a backwater valve is needed except in a flood plain where ample warning of backflow is possible.

Appeal Board Decision #1235

The Appeal relates to a fixture drain. Sentence 4.6.4.(2) applies and permits either a manually operated gate valve or an automatic backflow valve. The choice is that of the owner/contractor, not the authority having jurisdiction. The contractor in this case has chosen a manual gate valve and the Board considers this to be acceptable.

George R. Humphrey, Chair