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Eastern Idaho Sanitary Interceptor

Shelley, Idaho

Sanitary Sewer


Eastern Idaho Regional Wastewater Authority (EIRWWA)


Forsgren Associates


DePatco (Pilot), Bonniford (Phase I)



The first phase of the Eastern Idaho Regional Wastewater Authority’s (EIRWWA) Regional Wastewater Treatment Plant, with a price tag of approximately $21 million, was completed during 2009. The facility, located in Shelley, ID, was designed to handle up to 2 million gallons of sewage per day with the possibility of expanding to 8 million gallons per day. A large diameter sanitary interceptor line was run from Bingham to Bonneville counties, connecting Shelley with the City of Ammon.

During their search for the appropriate sanitary sewer pipe, the EIRWWA and the engineer on the project, Forsgren Associates, allowed DuroMaxx to perform a pilot installation to fully test the product before being considered. Upon the successful pilot evaluation, DuroMaxx was then included in the evaluation process for the 14-mile interceptor.

After the comprehensive material evaluation, which included seven technologies, DuroMaxx steel reinforced polyethylene pipe was chosen. Because of the high strength and exceptional joint tightness, DuroMaxx provides outstanding value. Not only did it meet the initial testing requirements, but it was able to provide the long-term infiltration and exfiltration needs. DuroMaxx is also extremely resistant to corrosive effluent and met the hydraulic efficiencies to allow for the minimum slope and longer runs.

The pilot project installation included 600 LF of 42-in. diameter and 600 LF of 48-in. diameter DuroMaxx sanitary sewer pipe at depths ranging from 12 to 20 feet. In-situ sieved materials were used for bedding and backfill. The pipe was inspected for shape control, and the joints were subjected to a low-pressure air test.

“As required by the Department of Environmental Quality (DEQ), the integrity of the gravity sewer installation was tested to confirm there was little or no infiltration or exfiltration from the pipe” said Dave Noel, P.E., Forsgren Associates, Inc. “The 42-in. and 48-in. pipe segments demonstrated sufficient construction and passed the low pressure air testing requirement. DuroMaxx was chosen for the remaining 14 miles of pipeline because of the exceptional pipe performance in the pilot installation and the proposal evaluation process”

The entire project consisted of 4 Miles of 36-in. diameter, 2.25 Miles of 42-in. diameter and 7 Miles of 48-in. diameter DuroMaxx steel reinforced polyethylene pipe. Phase I construction began in fall of 2009 with a projected completion by spring 2011. This project will provide for economic development by protecting precious groundwater resources within the region and allow for community growth along the interceptor line. Partnering with neighboring communities on projects like these improves public health and safety, protects natural resources and infuses funds into the local economy.

Technical Description:

  • DuroMaxx®
  • 4 Miles of 36-in dia.
  • 2.5 Miles of 42-in. dia.
  • 7 Miles of 48-in. dia.

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