Trench Shoring for Large-Diameter Water Pipelines: The KWA Flint Water Crisis Solution

When the Flint water crisis erupted into national headlines, the focus turned to the aging infrastructure that had allowed lead to contaminate a city’s water supply. The long-term solution was already underway: the Karegnondi Water Authority (KWA) pipeline, a $285 million project bringing clean water from Lake Huron across 75 miles of Michigan. This massive infrastructure undertaking required contractors to solve complex trenching and shoring challenges, particularly when installing 60-inch-diameter steel pipe through challenging soil conditions. For building professionals and contractors working on large-diameter water infrastructure, the KWA pipeline offers valuable lessons in trench protection, equipment coordination, and customized shoring solutions. Understanding best solutions for hard water understanding water softeners and treatment systems also becomes relevant when considering the full scope of water quality infrastructure projects.

The Scale of the KWA Pipeline Project

Project Overview and Background

The Karegnondi Water Authority pipeline represents one of Michigan’s most significant infrastructure investments in decades. Ground was broken in 2013 on a multi-year water intake pipeline project designed to bring raw water from Lake Huron west along the I-69 corridor through Sanilac, Lapeer, St. Clair, and Genessee Counties. The pipeline would ultimately service the City of Flint and surrounding communities, providing a permanent solution to the water quality crisis that had made national headlines.

The total project scope includes several major components:

• A new state-of-the-art water intake facility boring 6,000 feet into Lake Huron
• Two water treatment plants for processing raw water
• Three new pump stations to maintain flow across 75 miles
• Approximately 68,500 linear feet of 60-inch-diameter spiral steel transmission pipe installed by Zito Construction
• An earlier phase installing 36-inch-diameter steel Class 150 pipe across 14 miles

Zito Construction, a family-owned Michigan firm specializing in excavating, road building, water mains, and sewer mains, was contracted by the KWA for two critical phases. After completing the 36-inch pipe installation from Genessee to Lapeer County in 2014, the company received an approximately $18 million contract to install the much larger 60-inch-diameter transmission pipe across parts of Lapeer County.

Challenges of Large-Diameter Pipeline Installation

Installing 60-inch-diameter pipe presents unique challenges compared to smaller utility lines. Zito Construction worked with extremely long 50-foot joints of pipe, with more than 1,600 jumbo pieces needing placement in an open cut trench ranging from 5 to 25 feet deep. Because any trench deeper than 5 feet requires a trench protection system under Occupational Safety and Health Administration regulations, the contractor needed a shoring solution that could accommodate both the depth requirements and the unusual pipe dimensions.

Ground conditions along the pipeline route complicated matters further. The soil profile ranged from sandy to swampy, making traditional sloping approaches impractical. As John Zito, president of Zito Construction, noted, sloping would have required removing entire road sections in some areas, making it neither economical nor feasible. The team recognized early that a custom trench box would be essential to the project’s success.

Customized Trench Shoring for Oversized Pipe

Designing the Solution

When standard trench shielding would not accommodate 50-foot pipe joints, Zito Construction turned to Efficiency Production, a leading manufacturer of trench shielding and shoring equipment. The engineering challenge was significant: how do you lower a 50-foot steel pipe into a trench box and maneuver it into position?

The solution combined two trench shields with custom high-clearance arches. Rather than using standard spreader pipe on the abutted ends, Efficiency Production designed hi-clearance arches that provided the necessary vertical room for pipe installation. Mike West, vice president of engineering at Efficiency Production, explained that the company had built similar custom shields for installing pipe joints of 50 feet or longer, but the KWA pipeline required a unique configuration: a lead box significantly longer than the trailing box.

Technical Specifications of the Custom Shield

The custom trench shield assembly consisted of two connected boxes working together as a single unit:

The boxes were secured together with shackles for easy pulling through the trench as work progressed. The hi-clearance arches on one end of each box were abutted to each other, creating more than 11 feet of pipe clearance. This provided the excavator operator and crew sufficient room to angle the spigot end of each 50-foot pipe into the connected boxes and up to the bell end of the previously installed pipe.

Installation Workflow

The installation process followed a carefully coordinated sequence:

1. The excavator operator angles the 50-foot pipe joint into the lead box
2. The pipe is guided under the hi-clearance arches toward the bell end of the installed pipe
3. The joint is tack-welded and heat shrink wrapped on the exterior
4. A welding crew from National Welding, a Utah-based subcontractor, traverses the inside of the pipeline
5. The interior joints are permanently welded from within the pipe
6. The combined trench shield assembly is pulled forward for the next joint

Zito Construction achieved a record of 11 pipe joints installed in a single day using this system. The company anticipated completing its section of the pipeline by June 2016.

Equipment Fleet and Site Management

Heavy Machinery Deployment

Wrangling both 50-foot pipe joints and a 60-foot combined trench box required a substantial equipment fleet. Zito Construction deployed multiple excavators, loaders, and support equipment to maintain productivity across the pipeline route:

• Cat 345D, Cat 349EL, Cat 375L, and Cat 390F excavators for trenching and pipe handling
• Cat 966G and Cat 950G wheel loaders for material handling and site work
• John Deere 450J and Cat D3 dozers for grading and backfilling
• Dewatering equipment from Mersino Equipment Rental for managing groundwater in swampy sections
• Two Efficiency Production Stone Mizer bedding boxes for pipe bedding material placement

The varied equipment mix highlights an important lesson for contractors tackling large-diameter water pipeline projects: having the right machines for each phase of the operation is critical to maintaining production rates. The excavators handled the primary trenching and pipe manipulation, while loaders and dozers supported bedding, backfilling, and site preparation.

Groundwater Management

The swampy soil conditions along portions of the pipeline route required active dewatering throughout the installation. Jeremy Drielick, senior engineering technician at Rowe Professional Services Company (the engineering firm responsible for Zito’s portion), described the ground conditions as sandy to swampy. This variability demanded flexible approaches to water management, with dewatering equipment positioned ahead of the trenching operation to lower the water table and maintain stable trench walls.

Effective dewatering is essential for several reasons: it prevents trench wall collapse, allows proper pipe bedding installation, and ensures safe working conditions for the welding crews inside the pipe. For contractors planning similar projects, investing in adequate dewatering capacity and planning for variable groundwater conditions can mean the difference between steady progress and costly delays.

Lessons for Infrastructure Water Projects

Key Takeaways for Contractors

The KWA pipeline project offers several practical lessons for contractors and engineers working on large-diameter water infrastructure:

• Custom shoring pays dividends. Off-the-shelf trench boxes cannot accommodate 50-foot pipe joints. Investing in custom-engineered shoring solutions, while more expensive upfront, enables production rates that justify the cost. Zito’s record of 11 joints per day demonstrates what is achievable with the right equipment.
• Hi-clearance arches solve the clearance problem. Standard spreader pipe limits vertical clearance in trench boxes. Custom arches provide the headroom needed to angle long pipe joints into position without compromising worker safety.
• Combined box configurations increase efficiency. Using a longer lead box for pipe receiving and a shorter trailing box for connection work optimizes the workflow within a single shield assembly.
• Soil assessment drives shoring decisions. Sandy to swampy conditions ruled out sloping and made custom shoring the only viable option. Early geotechnical investigation is essential for selecting the right approach.

The Broader Impact

Once completed, the KWA pipeline would supply treated and untreated water to municipalities, industrial customers, agribusinesses, rural agriculture developments, and residential commercial manufacturers across the region. The boundaries of the water supply encompass over 2,400 square miles and serve more than half a million people.

For contractors and building professionals involved in water infrastructure, understanding both the large-scale project management and the technical details of pipe installation is essential. Proper water heater selection and installation tank type tankless systems, for instance, are just one part of the broader water delivery infrastructure that begins with projects like the KWA pipeline. Similarly, innovative approaches to materials, such as plastic water bottles repurposed as roofing tiles an innovative building material solution, demonstrate the construction industry’s capacity for creative problem solving.

Coordinating a project of this scale also requires robust management systems. How cloud based project management software helps contractors think strategically about resource allocation, scheduling, and communication becomes evident when examining multi-year infrastructure installations spanning multiple counties and involving numerous subcontractors.

Safety Considerations in Deep Trench Operations

The KWA pipeline project underscores the critical importance of trench safety in deep excavation work. With trenches reaching 25 feet deep, the consequences of inadequate shoring would be catastrophic. Occupational Safety and Health Administration regulations require trench protection systems for any excavation deeper than 5 feet, and the KWA project demonstrates how to exceed these minimum requirements through engineered solutions.

Key safety practices observed on this project include:

• Using custom-engineered shoring rather than relying on sloping in variable soil conditions
• Maintaining continuous trench protection throughout the pipe installation process
• Coordinating dewatering to prevent trench wall instability
• Utilizing a combined shield assembly that protects workers in both the pipe receiving and connection zones
• Implementing specialized welding procedures that allow crews to work safely inside the pipeline

For any contractor planning deep trench work, the KWA pipeline serves as a case study in how proper planning and custom equipment investment can deliver both safety and productivity. The investment in a custom shield assembly, dewatering systems, and the right equipment fleet enabled Zito Construction to maintain a steady production rate while ensuring every worker remained protected in the trench.

The Flint water crisis highlighted the consequences of neglected infrastructure, but the KWA pipeline project demonstrates what is possible when engineering expertise, contractor capability, and proper equipment come together. For contractors across the building industry, the lessons from this project apply to a wide range of underground utility work, from water mains to sewer lines to storm drainage systems.