Licking River Double Siphon

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The Licking River Siphon is the location of the largest sanitary sewer overflow (SSO) in SD1’s collection system. Controlling this significant overflow requires a multi-phase approach, the first of which is the installation of a second siphon pipe under the Licking River (downstream from the SSO) to provide more outlet capacity.

The project will include the installation of a second 12-inch siphon under the river to the combined sewer system. This project works in conjunction with a planned Licking River Siphon Equalization Tank (which will be part of the 2029 milestone SSO solution) to eliminate this Licking River Siphon SSO.

To construct the parallel 12-inch siphon, horizontal directional drilling was identified as the most efficient option due in part to the length of the river crossing, ground surface, river elevation profile and required diameter of the carrier pipe.

This project is expected to reduce 42 million gallons of typical-year SSO volume, but the EQ tank is required to fully eliminate the SSO and offset CSO impacts downstream of the double siphon.