In April 2001 Riggs Engineering carried out a preliminary engineering study of proposed repairs at the finger docks at CCIW in Burlington. Based on previous studies the total value of repairs under consideration was in the order of $550,000. The largest single item related to the deteriorated condition of the H-piles that support the structure. A small scale repair utilizing “Fabriform” jackets had been previously carried out on one of the docks at this location. As part of its investigation Riggs Engineering had a coupon removed from one of the H-piles and sent to a metallurgist for corrosion analysis. We suspected that the
composition of the steel was contributing to the rapid rate of corrosion. Detailed analysis,
however, showed that the steel composition was acceptable and that the rapid corrosion was due to the environment, particularly biological factors.

Riggs Engineering analyzed the dead and live loads on the structure and concluded that the piles had sufficient axial capacity even with loss of material up to 50%.
Our design approach was to restore the strength of the piles using prefabricated steel jackets. Constructability, given the close quarters and large number of batter piles, was a prime consideration and highlighted the advantages of the steel jackets compared with steel reinforced fabric jackets.

Tenders closed under budget and a contract was awarded to Watech Services Inc. with a completion target of December 2001. The project proceeded smoothly on site and the diving contractor reported that the drawings detailed all necessary refinements to
accommodate varying site conditions. Thus the installation was easier than he
anticipated and the project finished on time and on budget.

Mr. Lampkin was the lead engineer for this project. Mr. Denniss ably handled field review services and weekly client progress reports.