Client: City of Lewes, Delaware

Increasing development pressure in the historic City of Lewes threatened to convert an historic boatyard along the Lewes and Rehoboth Canal into condominiums.

Wanting to preserve the site for future generations, the City acquired the 3-acre parcel and incorporated a canalfront park into their overall master plan. The site is lewes1located a block from the historic downtown shopping district and adjacent to 70-year old Lightship Overfalls and City recreation areas. Duffield Associates was chosen to provide civil, environmental, structural, and geotechnical engineering and construction review services for the project’s design architect.

Elements of the project include: a scenic waterfront boardwalk; a handicap accessible fishing pier; floating docks; a restroom facility with an overlook pier; shade arbor; stone walkways, and landscaped areas.

The site’s historic use as a boatyard left a legacy of substances in site soils that required environmental remediation. Identified as a brownfield site by the State of Delaware, the project required remedial action to address environmental concerns. By integrating the remedial environmental design and site design, Duffield minimized remedial costs and waste production and was instrumental in creating a park that is an asset to the community. For example, our design team arranged for storage of the project’s wet dredged sediments in exchange for using dried dredged sediments for remedial cover in the park, effectively recycling materials.

Our civil engineering design functionally and aesthetically integrated new site structures and landscaping. Innovative stormwater management design includes multiple bioretention and infiltration areas with check valves to minimize site flooding during high tides and flood surges.

Our team provided structural engineering services for the foundations and superstructure for the boardwalk, restroom and overlook pier, and other site structures. The firm also coordinated the floating dock pile installation and connection of the docks to the boardwalk landing areas.

To address aquatic/wetland regulatory concerns, the proposed design called for the boardwalk to be constructed over an existing bulkhead. This aging bulkhead, while stable, exhibited some movement as the first boardwalk supporting piles were driven. The firm’s designers determined that the existing bulkhead could be stabilized in place to prevent detrimental movement and to preclude the need for future stabilization once the bulkhead became inaccessible beneath the newly constructed board walk. An innovative and economical stabilization technique was recommended that involved constructing a unique revetment in front of the bulkhead. A stone riprap veneer was constructed over large sandbags resting on a thin articulating concrete mat. The mat was selected in order to bridge 5 feet of soft sediments which could not be removed due to bulkhead stability concerns.

The park has become a popular destination for tourists and residents – the perfect location for a day visit with family and friends or an after-dinner stroll to take in the sights and sounds of the canal. The new waterfront park has ensured the preservation of the historic nethouse, which serves as a museum documenting the history of the Lewes and Rehoboth Canal and its importance to the development of regional commerce.