Overview
Ballard was directly contracted for the four-phase design-build project including repairs to the Indiana American Water intake crib located on Lake Michigan, as well as removal of debris and foreign material from the intake tunnel. Ballard collaborated with a third-party engineering firm to design a replacement for the existing crib structure, which would be removed as per the project scope. The demolition of the existing, and installation of this new crib structure was executed by Ballard via the use of derrick barges and an experienced dive team. Ballard also supplied an in-house Remotely Operated Vehicle (ROV) and diving inspection of the intake pipeline with a penetration distance of 16,000 feet.

Scope of Work
Phase One included the design and survey of the intake system and crib structure. Ballard provided an in-house ROV inspection with video and sonar to a penetration depth of 16,000 feet and diving inspection services to assess the current condition of the intake pipeline and the crib structure.

Phase Two of the project required the removal of the broken-up portions of the intake crib, years of sediment buildup, logs, and mussels from the bottom of the intake tunnel. This work was performed with mixed gas diving from a floating platform to depths of 185 feet requiring specialized tooling and equipment.

Phase Three included the demo of the remainder of the crib structure down to its foundation. Once the old crib structure was removed, divers began preparation for the new precast crib components installation. A temporary chlorine halo diffuser ring was also constructed and installed inside the upper area of the vertical intake shaft for temporary zebra mussel treatment.

Phase Four included the construction of the intake crib. Ballard’s unique design of utilizing precast concrete and the use of the original intake foundation was a key component of our success with this project. Ballard constructed the new custom designed interlocking crib structure on land and then mobilized the crib components to the intake site for installation. The new sections of the crib weighed between 10,000 to 40,000 pounds and were installed with a barge mounted crane and diver support. During the installation process, divers utilized epoxy anchoring systems to assemble the modular intake structure and secure it to the crib foundation.

Innovative Solutions
The installation of the new crib structure was conducted in phases due to the precast nature of the concrete. Each precast segment had an abnormal center of gravity which required Ballard to utilize specialty rigging techniques to maintain a high level of safety on the jobsite. The intake pipeline inspection required a high level of precision ROV piloting due to the large penetration depth required (1,600 feet). The Ballard ROV and expert dive team was successfully able to identify and remove or mediate any excess growth within the large intake pipeline via specialized techniques.

Results
Once completed, the zebra mussel chlorination system was upgraded by the installation of a twin set of three-inch diameter HDPE chemical feed lines through the 16,000-foot-long horizontal tunnel system, along with a new upper diffuser ring. The pipeline was successfully cleared of debris and excess marine growth and retuned to optimal allowable flow.