A Case History of Bulkhead Design and Construction for Environmental Dredging and Soil Retention-PPT Presentation

PPT Presentation

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The project replaced deteriorated 1944 bulkheads along a tidal inlet where corrosion had created large openings, allowing upland soil to enter the waterway. Because the sediment contained PAHs, PCBs, and heavy metals, dredging required a new wall capable of retaining contaminated soil. Design constraints included limited encroachment, unusable existing anchors, corrosive soil and water, and a 75-year service-life goal.<br /><br />A cantilevered steel sheet-pile wall was designed using limit-equilibrium and soil–structure interaction analyses. To address corrosion, the design combined marine-grade A690 steel with an inorganic zinc primer and coal-tar epoxy coating. Alternating 24- and 30-foot sheet piles were selected to increase support while using the same quantity of steel already ordered. Coating damage during installation required careful handling and repairs; weep-hole inserts provided drainage.<br /><br />Construction revealed softer soil than anticipated, indicated by low driving resistance. Soil parameters were back-calculated from installation records, prompting reassessment of wall stability. When remediation later required deeper dredging, the installed wall did not meet revised stability requirements. After considering alternatives, the team selected replacement of alternating sheet-pile pairs with longer piles, increasing embedment while retaining the installed 30-foot sheets.<br /><br />The completed bulkhead retained contaminated upland soil and helped prevent contaminated sediment from reaching the marine environment. The case demonstrates the value of adapting designs to field conditions, using actual driving data to refine soil assumptions, and selecting construction details that balance performance, cost, and site constraints.

Keywords

bulkhead replacement

sheet-pile wall

contaminated soil retention

tidal inlet

corrosion protection

A690 steel

PAHs PCBs heavy metals

soil-structure interaction

dredging stability

marine construction