Collapsed Bulkhead

Collapsed Bulkhead

MARINE LUBRICANTS EMERGENCY WHARF RECONSTRUCTION
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Marine Lubricants is located along a bend in the Christina River just above the Port of Wilmington.  The firm’s vessels supply specialized lubricants and fuels to cargo ships plying the Delaware River.  The firm loads its boats from a large wharf along the Christina River.

In early July 2011, the owners of the facility observed cracking and settlement in the pavement behind the wharf.  The situation became dire when a section of the existing bulkhead and loading dock, approximately 80’ by 40’ deep, collapsed into the river bringing operations to a standstill.  Strong currents caused severe erosion along the riverbank, exposed by the wharf collapse, posing the threat of undermining the foundation of an

Stabilization

Stabilization

adjacent office and warehouse.  Given the impacts to both river navigation and to the firm’s business, Marine Lubricants immediately retained CABE to assist them in repairing the damage.

The original loading dock included a “low deck” which was common at ports along the Delaware River.  A low deck consists of a pile supported platform extending from shore out into the deeper waters of the navigable waterway.  Earth fill and a paved surface was often placed over these low decks enabling direct access to vessels moored in the channel.  Many of these structures were constructed in the early 1900s and have exceeded their useful life.  The substructure often remains hidden and unknown, unless there is a problem, such as occurred in the case of the Marine Lubricants’ collapse.

At the Marine Lubricants’ site the low deck was a timber pile supported concrete platform over which fill

After

After

material and a paved surface had been placed.  While the actual cause of the collapse remains unknown it was likely associated with the age of the structure and erosion along and adjacent to the old timber pile foundation and wooden retaining structure.

The immediate stabilization and repair of the wharf was critical to continued operation.  To meet the challenge, CABE aggressively addressed the regulatory and permitting concerns of the Army Corp of Engineers, DNREC and the City of Wilmington while concurrently performing the necessary field investigations, preparing the reconstruction design and construction bid documents, and soliciting bids from qualified contractors.

The reconstruction design included the demolition of remnants from the existing wharf and the  installation 130 feet of steel sheet pile to a depth of 50 feet anchored by a pile supported concrete deadman to serve as the riverward edge of a new wharf.  The construction required the removal of collapse debris from the Christina River and the in-fill of the remaining areas of the historic low deck.

The wharf repair contract was awarded to Kuhn Construction Company.  Construction was started in September 2011 and was completed on time and on budget in seven weeks.   This expedited schedule enabled Marine Lubricants to resume full normal operations.

CABE’s team provided a full complement of services including regulatory permitting and liaison, geotechnical investigations, marine structure engineering, construction administration and testing and inspection services.