MULTIPURPOSE DOCK ON THE DELAWARE RIVER
PORT OF WILMINGTON, DELAWARE
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Duffield Associates, Inc. was initially retained by the Diamond State Port Corporation to complete a feasibility study for its first new dock and berth on the Delaware River. The study involved: bathymetric surveys; subsurface exploration, including land and water-based borings and soil/environmental sampling to address both geotechnical and environmental issues; location and configuration of the proposed berth, including performing sediment transport analyses to determine initial and maintenance dredging requirements; evaluation of dredging material disposal options/sites; preliminary design of site roadways, access causeways, and dock structure; identification of submerged cultural resources and other environmental permitting issues, including wetland area identification and mitigation; regulatory agency liaison; and preparation of a preliminary construction cost estimate.

In conjunction with another engineering firm, a final design was developed to include an 875-foot long pile-supported dock. The location and orientation/configuration of the berth were developed to eliminate initial and long-term maintenance dredging which would have taxed the already capacity-challenged Wilmington Harbor.

Design services provided by Duffield Associates included technical design of pile foundations to support the berth and trestle, which traversed a Corps of Engineers containment dike, a 10 ft soil surcharge to pre-consolidate a 17 acre paved parking lot over a former dredge disposal area, analysis and design for relocation of several earthen containment dikes over soft recently placed dredged materials and pavement design over the unconsolidated dredged materials, existing dikes and fast lands. Duffield Associates was subsequently retained for construction review of Access Road and berth construction. Services included: review of the test pile program (including review of splice welds, axial load, and pile dynamic testing); production piles including splice welds; bitumastic coating for production piles; earthwork; and concrete activities.

Since completion of the initial construction in 2002, Duffield Associates has been retained by the DSPC and DSPC's engineers and contractors to provide additional design and construction review services related to the 17-acre paved parking lot and a new mooring dolphin located downstream of the berth. Duffield Associates' services included:

• Design and construction review of a "wearing surface" for the 17-acre lot to allow for the storage of bulk materials;
• Performance of a "desktop" geotechnical evaluation for the new mooring dolphin utilizing water-based borings previously performed by Duffield Associates;
• Assisting Diamond State Port Corporation's structural engineer with the development of technical specifications for the pile supported mooring dolphin and access catwalk; and
• Developing driving criteria and reviewing construction of the piling (which included pile dynamic testing) for the mooring dolphin and catwalk; as well as reviewing reinforcing steel and concrete placement for the mooring dolphin.