Old Croton Aqueduct – Ossining Weir Chamber

September 17, 2016 – Ossining, NY

I planned my 26 mile section hike of the Old Croton Aqueduct to coincide with a tour of the weir chamber in Ossining, NY. That is why my stopping point for the first leg and starting point for the second leg was the Ossining weir. The tour was given courtesy of Friends of the Old Croton Aqueduct. They conduct tours occasionally and I am glad that I attended this most informative tour. First off, they showed a short film about the history of the aqueduct. There were approximately 70 people in attendance so they broke us up into two groups. I made sure that I was in the first group that made its way to the weir. I had a hike to do following my visit to the weir and did not want to sit around waiting when I could be hiking.

Old Croton Aqueduct - Ossining Weir Chamber

Old Croton Aqueduct – Ossining Weir Chamber

The weirs along the Old Croton Aqueduct were structures that were built right over or next to the aqueduct, enabling direct access to the aqueduct tunnel. This allowed for maintenance and repair by diverting the waters to a nearby waterway.

Ossining Weir

Ossining Weir

The Ossining Weir is twenty feet long, ten feet wide, and thirty feet high, including the portion of the weir that is built underground for the waste-water conduit.

Ossining Weir

Ossining Weir

The Ossining weir was a later addition (1882) and a modernization of the system. Upon entering, inside to the left, is an effluent valve wheel. It was used in order to allow the water coming southward in the tunnel to be diverted into a 4 foot drain pipe which led to the Sing Sing Kill under the arched aqueduct bridge.

effluent valve wheel

effluent valve wheel

effluent valve wheel

effluent valve wheel

The wheel opens and closes the release valve which is directly underneath.  It would keep water pressure from building up on the gate or from overburdening the tunnel with water.

release valve

release valve

The water is released through the above opening, which in turn flows through this 4 foot drain pipe under the arched aqueduct bridge.

drain pipe

drain pipe

drain pipe

drain pipe

And then flows into the Kill Brook via this stone splash block.

stone splash block

stone splash block

Walking down the stairs and turning right, now looking south into the tunnel. This part of the tunnel is built into the arch bridge which carries the water over the Sing Sing Kill.

looking south

looking south

This steel gate is lowered to divert water away from the south side of the tunnel for routine maintenance and/or repairs.

steel gate

steel gate

Looking north through the tunnel, this catwalk was added for visitors to walk on during tours.

catwalk - looking north

catwalk – looking north

Walking to the end of the catwalk, still looking north. Notice the waterline that is visible along the side of the tunnel. They incorporated the rock of the hillside as the roof.

looking north

looking north

A look up at the inside of the weir. You can see the ventilating hole on the brick lined ceiling. Also visible is the steel beam that supports the weight of the steel gate.

Ossining Weir - interior

Ossining Weir – interior

I hope that you enjoyed the virtual tour of the inside of the Ossining weir chamber. Don’t forget to follow my blog to keep up to date on my ramblings throughout the Hudson Valley and beyond. Until next time folks, keep a steady flow.

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