LANGLEY AIR FORCE BASE, Va. –
Rip Rap from Richmond is coming by the tens of tons to Langley. The 330 million year-old rock is Petersburg granite and is being trucked down to the base from a Luck Stone quarry. It will be placed along Langley's vulnerable waterside perimeter to strengthen and protect the shoreline around the base.
The base's flight line is only 11 feet above sea level; so nor'easters, hurricane-strength winds and flooding water can take a toll on the fragile coast encircling the base. So, will this project help prevent future flooding in any way? According to Neville Reynolds, a project designer with Vanasse Hangen Brustlin, Inc, -- not directly.
"Flooding is essentially controlled by the elevation of the land," said Mr. Reynolds. "Neither the revetment, nor the sills and marsh planting will effectively raise the land, nor act to block water as flood and storm surge control."
There will be a living shoreline, which is made of stone sills and sand placed as a planting terrace for big cordgrass and salt meadow hay. All plantings will be native to Virginia.
"This will prevent erosion and provide habitat by establishing a more natural estuarine edge at a gradual slope that allows dissipation of wave energy." said Mr. Reynolds.
According to the Virginia Institute of Marine Science, headquartered in Gloucester, living shoreline treatments address erosion in lower energy situations by providing long-term protection, restoration or enhancement of vegetated shoreline habitats through strategic placement of plants, stone, sand fill and other structural or organic materials.
Living shoreline treatments do not include structures that sever the natural processes and connections between uplands and aquatic areas. The shoreline restoration will create 6,064 square feet of tidal wetland mitigation and 4,733 lineal feet of tidal stabilization revetments of which approximately 3,500 feet will be gapped-sills which provide a calmer backwater along the shore while maintaining the aforementioned connections.
"Plants are key to this project," said Reed Jeavons, 633rd Civil Engineer Squadron natural resources planner for Langley. "The cordgrass and saltmarsh hay plantings we'll use are halophytes, which are well suited to tidal inundation."
Because those tides are saltwater, very few plants can handle the salinity and continue to grow. These plants also have other valuable characteristics.
"The roots of these grasses stabilize the marsh soils, and the blades or leaves dissipate wave energy, which protects the shoreline," said Mr. Jeavons.
According to Environmental Concern Inc., a 501(c)3 public not-for-profit Maryland corporation dedicated to working with all aspects of wetlands, "Deep rooted native grasses create a natural landscape. The gradual slope of the constructed marsh presents a gracious, aesthetically pleasing entrance to tidal waters."
Earlier this month two 633rd CES construction inspectors, Joseph Sirois and James Allen along with Mitch Boozer with THR, the principal contractor, travelled up to the Richmond quarry adjacent to the James River. They inspected the granite rip rap to make sure gradation specifications were met.
For every 50,000 tons of rock, less than five percent could weigh more than 1,500 pounds. Rock weighing between 750 and 1,500 pounds could account for 50 percent, rock weighing between 500 and 750 pounds could account for 40 percent and the smallest stones, between zero and 500 pounds could account for only 10 percent of the sample.
The contract was awarded to THR Enterprises on Sept. 30 last year. The $5.4 million design bid and build project started in late April. THR has accomplished hurricane repairs on Langley structures in the past as well as other large construction projects at nearby military installations.
According to the book, "Langley Field - the Early Years," construction and fortification of the sea wall that lines the Southwest Branch of the Back River began in 1931. Before then the north shore was a mudflat, from the King Street Gate east to the Marina.
Between March and May 1934 the area around the officers' quarters and the area along the sea wall were graded, seeded and planted. Eight decades later, repairs to the sidewalk and seawall will total 2,678 linear feet. The estimated completion date is January next year.
"This is an important project for CE; one that will help protect the base and its assets," said Mr. Sirois. "Besides reducing the potential for future erosion of our shoreline, the aesthetics will be enhanced as well."