Tremie

A tremie is a watertight pipe, usually of about 250 mm inside diameter (150 to 300 mm),^[1] with a conical hopper at its upper end above the water level. It may have a loose plug or a valve at the bottom end. A tremie is used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing. This produces a more reliable strength of the product. Common applications include the following.

Caissons, which are the foundations of bridges, among other things, that span bodies of water.
Pilings.^[1]
Monitoring wells. Builders use tremie methods for materials other than concrete, and for industries other than construction. For example, bentonite slurries for monitoring wells are often emplaced via tremie pipe.^[2]

^ ^a ^b Staff. "Concrete Pumping Products - Tremie Pipes". we-couplings.com. Anderton, Lancashire: W.E. Couplings Ltd. Retrieved 1 June 2017.
^ Nielsen, David, ed. (1991). Practical handbook of ground-water [sic] monitoring. CRC Press LLC. p. 321. ISBN 0-87371-124-6. In wells more than about 50 feet deep, granular bentonite may be mixed with water and conveyed through a tremie pipe from the surface directly to its intended depth in the annulus. Pelletized bentonite is not effectively installed through tremie pipes.

[Tremie_pipes-1] Staff. "Concrete Pumping Products - Tremie Pipes". we-couplings.com. Anderton, Lancashire: W.E. Couplings Ltd. Retrieved 1 June 2017.

[2] Nielsen, David, ed. (1991). Practical handbook of ground-water [sic] monitoring. CRC Press LLC. p. 321. ISBN 0-87371-124-6. In wells more than about 50 feet deep, granular bentonite may be mixed with water and conveyed through a tremie pipe from the surface directly to its intended depth in the annulus. Pelletized bentonite is not effectively installed through tremie pipes.

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