NEABSCO CREEK BOARDWALK
Prince William County, VA
Neabsco Creek Boardwalk consists of 3,173 feet of new boardwalk across Neabsco Creek and its tidal marsh, just east of US 1 (Jefferson Davis Highway). The boardwalk spans from Neabsco Road on the south and extending across the Julie Metz wetlands north to Rippon Landing Community Park. The project also includes a viewing tower on the bank of the creek with an associated bridge connecting it to the main span.
The boardwalk extends the Potomac Heritage National Scenic Trail and allow visitors, residents, and students access to areas previously inaccessible.
The Robert B. Balter Company (Balter) provided subsurface explorations, materials testing and a geotechnical engineering evalutation of field and laboratory data for the the boardwalk and view tower. To minimize the impact on the wetlands, Standard Penetration Testing (SPT) was performed at each end with an All-Terrain Vehicle-mounted drill rig. The borings were drilled to extend through the soft tidal deposits and sample the denser soils of the Potomac Formation that lie below.
In addition to the SPT borings, Hand Auger borings and Muck Probes were performed across the marsh. Access to these borings was severely limited by environemental contraints and the tidal streams, which required the use of a small boat. Samples of various soil types were obtained using a hand piston sampler. The Muck Probes consisted of small diameter (approx. ½”) steel rods being inserted into the ground. By doing this, the depth to the denser Potomac Formation soils could be estimated where the resistance increased, allowing Balter to make recommendations for the required length of timber piles.
During construction, Balter served as the Special Inspector of Record for the Boardwalk providing full-time inspection of pile installation, boardwalk framing, and the installation of two 60 foot clear span bridges. The Boardwalk was constructed using “top-down” construction methods where the timber piles were installed using vibratory hammers. In addition, Balter provided assistance during specification preparation, bid review, and submittal review.
Finally, the project required pile load testing (axial, tension, and lateral), which was overseen and approved by Balter’s professional engineering staff.