Belle Fourche Irrigation brings two new concrete siphons on-line

96" and 84" RCP used to replace irrigation siphons

For nearly two decades, the Belle Fourche Irrigation District in South Dakota and the US Bureau of Reclamation had struggled with identified inefficiencies in two of their siphoned irrigation systems.  Indian Creek and Horse Creek, each siphoned water through large drainages to irrigate agricultural areas along the Belle Fourche River. 

Two massive steel above ground siphons, 96” in diameter, were determined to be replaced with an underground system to prevent thermal expansion, leakage and potential wash out, plus the 80 year old siphons had reached their design life.

Together, the Bell Fourche Irrigation District and the USBOR contracted with RESPEC Water and Natural Resources ( to replace both siphons, beginning late fall of 2013.  Reinforced Concrete Pipe, produced to ASTM C-361 with a progressive specification, was their material of choice.  In addition to the stringent requirement of C-361 R4, pipe was required to show proof of design at the production location, required hydrostatic and vacuum testing, joint tolerance and gasket compression calculations, ASTM C-1103 Joint Testing at installation, and a final Hydrostatic Test post installation.

The project was bid in early 2013, Heavy Constructors Inc. of Rapid City, SD was the successful bidder  (

The Indian Creek Siphon was installed the winter of 2013-14.  This consisted of 1250 LF of A50 and B75 96” RCP, the line contained several 7.5 and 15 degree bends, a blowoff manhole with fabricated fittings, and precast beveled end sections, for special tie in connections to the existing inlet and outlet structures.

The Horse Creek Siphon was installed the winter of 2014-15.  This consisted of 550 LF of A50 and C50 84” RCP, this line also contained several 7.5 and 15 degree bends, a blowoff manhole with fabricated fittings, precast beveled ends sections for existing structure tie ins, and two 84” to 96” fabricated increaser/reducers to help the tie in connections.

The C-1103 joint testing progressed right along with the product installation with full time Cretex representation, and the final hydrostatic tests were a success.

Especially challenging phases of the work involved winter construction conditions and diversion of the streams, during particularly high runoff periods.  Reinforced Concrete Pipe installed beneath the valley floor has reduced threats on the old existing pipes such as deterioration, joint leakage through thermal expansion, valley floods creating lateral loads and displacement of the old siphon.  Irrigation is vital to this agricultural area in SD, 450 cfs of necessary water from the Bell Fourche Reservoir could not be interrupted during the growing season.

Owner:  US Bureau of Reclamation

Operator:  Belle Fourche Irrigation District

Engineer:  RESPEC Water and Natural Resources

Contractor:  Heavy Constructors Inc.

Supplier:  Cretex Concrete Products, Rapid City, SD

               William S Huber, Sales Engineer

               Richard J Langguth, Sales Manager