Filter Diaphragm may Require Downstream Pipe Replacement or Extension

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Message: Consider installing a downstream sand filter during any outlet conduit rehab/replacement.

A highway occupies the crest of this dam in Southeast Alaska. The dam functions as a dam, highway, and utility causeway. The inlet structure was in poor condition and the outlet conduit needed to be either replaced or rehabilitated. The project was designed as a slipline to prevent the need to close down the highway during construction. The 48" existing HDPE conduit was sliplined with a 42" HDPE pipe. The dam was constructed in 1941 and does not have a downstream filter. In order to bring the dam up to current standards, a filter diaphragm was added retroactively, as shown in the renderings below.

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Note: The content on this page was originally created as part of DamOutletWorks.org (DOWL, 2018). It has subsequently been updated and reformatted as part of the Dam Safety Toolbox.
Revision ID: 4750
Revision Date: 12/02/2022