Gannett Fleming: Gilboa Dam

System overhaul of a dam

By Gannett Fleming August 17, 2015

Engineering firm: Gannett Fleming
2015 MEP Giants rank: 47
Project: Gilboa Dam
Address: Gilboa, N.Y., United States
Building type: Dam
Project type: System overhaul
Engineering services: Automation, controls; Commissioning, retro-commissioning; Electrical, power; Fire, life safety; HVAC, mechanical; Lighting; Energy, sustainability; Plumbing, piping; Communications; Lightning protection
Project timeline: 6/14/2006 to 6/14/2018
MEP/FP budget: $4,200,000

Challenges

Gilboa Dam, located 110 miles northwest of New York City, plays a crucial role in providing water for 9 million residents of the city and surrounding communities. In operation since 1927, the dam is undergoing renovations and improvements to extend its service life and comply with dam safety guidelines. In addition to bolstering the dam’s structural integrity, upgrades to the instrumentation and controls systems will make the dam one of the most technologically advanced dams in the world. However, rehabilitating the 88-year-old dam while maintaining full operations did not come without challenges.

The dam’s location on the East Coast makes it prone to hurricane-induced flood events. Storms like Irene and Lee in 2011, then Sandy in 2012, were tropical hurricanes—ocean-based storms that spun ashore and brought intense winds and rain inland. The three storms that hit New York during Gilboa Dam’s rehabilitation unleashed unprecedented amounts of water on the sensitive controls equipment. Even when the weather isn’t extreme, the dam’s physical environment challenges the integrity and safety of the electronic systems. Spaces within the dam are wet and cave-like, requiring creative solutions for keeping the equipment dry.

Gannett Fleming’s systems-engineering work brings together systems that were provided in five different contracts and that were in various stages of completeness, which provides a schedule and coordination challenge. Additionally, many of the systems are interconnected and must communicate with each other, posing additional challenges. Portions of the new structure were designed with a 100-year design lifetime, which is longer than the expected lifetime of the electronic systems. Gannett Fleming was challenged to account for anticipated electronic-system maintenance and upgrades.

Solutions

To address challenges posed by weather and the wet nature of the dam, Gannett Fleming worked closely with an integrated team to design electronic system-installation details that guard against water intrusion and submersion without damage. In addition to protecting the equipment from water, the team accounted for the remote location of the dam, where it would be difficult for an operator to be stationed. The team set up a remote communications system that allows equipment to be monitored long-distance, eliminating the need for an on-site operator.

Gannett Fleming designed a common communication infrastructure to facilitate interconnection of dam safety instrumentation. Systems included supervisory control and data acquisition, dam control, intercom, intrusion detection, closed-circuit television, access control, mechanical and ventilation, lighting control, alarm annunciation, telephone, network data communications, gate control, and fire alarm systems. A fully redundant fiber optic network interconnects the various systems. This network provides the backbone that allows the systems to communicate. As the communication system was installed, equipment installed under previous contracts needed to be operational and protected from construction activity. The existing equipment was transferred to the new system to provide continuous dam operation monitoring without interruption.

Gannett Fleming designed the infrastructure that would last the life of the dam structure. Stainless steel conduit and specifically designed expansion couplings were installed to provide a reliable path between systems. Equipment enclosures are designed to easily accommodate equipment upgrades and replacements as the equipment ages and new technology becomes available.

Due to the unique physical nature of Gilboa Dam, some instruments could not be factory-calibrated to the specified load ranges required at installation. As high-tension load cells were installed, readings were taken from a traceable calibrated hydram. This data was used to field-calibrate the load cell for the appropriate load range and installation.