Top Projects 2019: Infrastructure & Utility

IBR Staff//September 23, 2019

Top Projects 2019: Infrastructure & Utility

IBR Staff//September 23, 2019

Phase II Wastewater Treatment Plant

At a special awards event held on Thursday, Sept. 19, this project was awarded first place in the Infrastructure & Utility category by the Idaho Business Review. The publication is available for free download.

Due to significant wastewater loads from the local dairy industries, the city of Jerome was required by the EPA to improve the effluent of its wastewater treatment plant. This resulted in a two-year expansion plan between the city, Keller Associates and RSCI. in addition to expansion, the plan included several upgrades and one complete rebuild of area conveyance lift stations. This project included construction of 24 new treatment/conveyance structures and the expansion of nine others. New structures include membrane facilities, clarifiers, aeration basins, pump stations, diversion structures, anaerobic digesters, solids handling facilities, gas handling facilities and headworks facilities.

RSCI performed approximately 80% of the project, including 5,000 cubic yards of structural and site concrete. In addition, a complex system of custom-fabricated Aluma Beam radius formwork sped construction of the 28-foot-tall digester structure walls.


Sitework included over 13,000 linear feet of underground yard pipe. Of that, 2,500 linear feet at a 42-inch diameter required blasting and/or mechanical rock breaking. In addition, one of the final connections required RSCI to build a coffer-dam to isolate one of the connections, and RSCI executed a plan that allowed the plant to continue operation.


RSCI constructed a 35-foot-tall gang form system for large, efficient, digester wall placements. The team also used an innovative approach for the placement and finishing of the clarifier base slabs for efficiency and accuracy, completely eliminating the need for a grout topping. In-lieu of the traditional clarifier structure base slab construction, RSCI coordinated adjustments to the clarifier base slab structure to allow the base slab to be placed monolithically using a custom-built finishing screed. The slab eliminates the need for water-tight joints between placements, greatly reduces construction duration of the structure and provides a higher quality product to the owner.


Prior to the improvements, the primary treatment systems were removing approximately 30% of the incoming biochemical oxygen demand and total suspended solids. Upon completion, the plant is able to remove approximately 90% of the incoming load in the primary treatment systems (biotowers and clarifiers). This significant reduction in load to the secondary treatment system not only provided the city with the tools it needed to meet its permit, it made it possible for new industries to be developed in the city.

The project also included energy efficient equipment and technologies, garnering $1 million in energy incentives from Idaho Power.

Ada County Landfill, North Ravine Cell Stage 3

This project was awarded second place in the Infrastructure & Utility category by the Idaho Business Review.

This project provided finished and operable landfill liner cell expansion for the Ada County Landfill NRC Stage 3 Project. The work included a lined landfill cell, haul roads, access road at NRC, access roads at the operations area, landfill gas, leachate siphon control system, leachate piping systems, and associated site grading and utility systems improvements. It included moving embankment, installing piping, utility relocation for fiber optic cable and plumbing and much more.

Innovations included the construction of new temporary haul roads rather than a large conveyor system. The change meant major savings in equipment rental costs and scheduling while also allowing the team to complete work more quickly. The team also installed a paved pad where it transloaded the rock.

It was critical for work to be performed safely while existing facilities continued to operate without interruption. A daily, unified effort between Knife River and Ada County facilitated the delivery of an accident free and safe project.

The project also overcame challenges such as grading on a steep slope and having a small staging area, and it faced a tightly compressed schedule.

Indian Creek Plaza

This project was awarded third place in the Infrastructure & Utility category by the Idaho Business Review.

The Indian Creek Plaza is a four-season public plaza located in Downtown Caldwell, Idaho. The 20,000-square-foot plaza is a cornerstone project in the revitalization of downtown Caldwell, turning it from a struggling commercial district into a thriving destination. It is a focal point from which the community’s historic architecture, arts community, eateries, shops and nightlife can be showcased.

During the summer months, the public plaza caters to outdoor concerts, cultural events, festivals, movies, urban markets and other community activities. When the weather turns cold, the plaza is transformed into an Ice Ribbon for skating.

With the Ice Ribbon, a significant retrofit to the existing Sweetwater building adjacent to the site was completed to house an ice skate rental shop, public restrooms and Zamboni storage.

The basement of the performance stage houses the ammonia-based refrigeration and process equipment.

Indian Creek Plaza was envisioned to be a community focus and catalyst for the revitalization of downtown Caldwell. The design incorporates state-of-the-art ice, water and audiovisual technologies while respecting the identity of the downtown’s Historic District.

City of Caldwell Wastewater Treatment Plant

This project was awarded honorable mention in the Infrastructure & Utility category by the Idaho Business Review.

The city of Caldwell is authorized to discharge treated effluent to the Boise River, and the wastewater treatment plant has a design capacity of 8.5 million gallons per day and includes fine screening, grit removal, primary clarifiers, conventional activated sludge aeration basins, final clarifiers, ultraviolet disinfection and a post-aeration basin. Primary sludge thickens in the primary clarifiers prior to being pumped to the anaerobic digesters. Then, the biosolids generated in the secondary treatment process are thickened in a dissolved air floatation thickener and pumped to the anaerobic digesters, where they are mixed with the primary solids. Solids treatment occurs in the anaerobic digesters.

There were four anaerobic digesters at the site before this project started. However, the two oldest digesters were built in 1950, and had been abandoned. The two operational digesters were at capacity, such that one digester could not be taken down for maintenance. By adding a new digester through this project, the City ensured it could continue producing Class B biosolids.