Pennoni Perspective Volume 23 • Issue 1 • Spring 2019 - Page 19

In 2013, Pennoni expanded its safety management capabilities to bring a new focus to the most important part of our business: our staff. With new resources in safety education, accident prevention programs, and injury case management, we have been able to greatly improve safety at the firm. One of the areas within the firm that safety is evident is in our Underwater Inspection group. Our Underwater Inspection group is made up of six Association of Diving Contractors International (ADI) certified divers, two of which are Professional Engineer divers, three engineer divers, and one technical diver. This team is responsible for underwater bridge inspections including wadeable water utilizing waders and a sounding rod, and deep water utilizing diving equipment. Our clients range from locally to worldwide, and include inspections at the Statue of Liberty, National Parks, and more. 130 feet. The bridge substructure consists of reinforced concrete columns resting on a pile cap supported by steel H-piles. During a routine underwater inspection of the structure in May 2015 for the Delaware Department of Transportation (DelDOT), potential areas of perforation in the steel H-piles were discovered which had not previously been reported. Other findings from this inspection included scaling, spalling, and cracking of the pile cap; knife SONAR gives DelDOT a visual representation of the divers findings. Safety is evident before our divers arrive at the job site. Prior to the start of each job, a site-specific dive plan is compiled including team members and roles, equipment needed, location maps of the job site and emergency facilities, etc. Prior to any work or set up, the team meets on site and discusses potential hazards and roles for the day. Local recompression chambers are contacted to confirm availability for use in the situation of a diving emergency. Once the dive station is setup, the team meets again and completes a checklist confirming that the setup was completed correctly. Our inspection group provides safety reassurance to our clients for their assets. Emergency inspections happen every day, whether due to impact damage or a natural disaster. Emergency inspections can be the result of impact, findings during a routine inspection, a flood or storm event, signs of settlement, public concerns, pre-construction, overloading, or known scour potential. With advancements in technology, emergency inspections can be completed immediately following an incident with high accuracy. One example of our inspection work can be found in Newport, DE, where State Route 141 is carried over the Christina River via a six-lane bridge. The vital area connection has more than 66,000 vehicles each day. The 19-span composite welded box girder bridge was built in 1978 and is 1,984 feet long with span lengths up to edging of the piles; and significant marine growth. These findings prompted an emergency in-depth inspection of the underwater portions of the bridge, including the use of SONAR to gather more detailed information. We also recommended a load rating to verify the capacity of the piles and to continue to monitor the structure. In-depth Level II and Level III inspections were performed on the exposed surfaces of the H-piles. During the Level II inspection, extensive cleaning of the piles occurred to locate areas of perforation using a Cygnus gauge. The Level III inspection involved ultra-sonic thickness gauge readings that were taken at the top, middle, and bottom of each pile, as well as at 15 locations along the perimeter. SONAR was used to create a visualization of the diver’s findings. The inspection revealed areas of microbial influenced corrosion (MIC) as well as areas of significant loss of protective coating. It was determined that the areas of perforation were most likely due to torch cutting of the steel piles during installation. Performing the in-depth underwater inspection allowed divers to use advanced technologies to collect precise data for use in performing a load rating of the structure. The findings allowed DelDOT to determine which course of action was necessary to ensure safety for the daily vehicles that travel across the bridge each day. P E N N O N I | 19