Sustainable Marine Lumber Helps Bridge Environmental and Structural Goals for the Ponquogue Bridge Restoration

By Richard Zimmerman, Jr.

For anyone whose travels have taken them to Long Island’s East End and, in particular, the old whaling town of Sag Harbor, New York, the Ponquogue Bridge is a recognizable structure. This 2,812 foot long bridge traverses over the Shinnecock Bay. Its piers are a favorite place for fisherman, and the waters under the south side of the bridge harbor a vibrant marine ecosystem making them a popular divers’ location. Looking at the Ponquoque Bridge today, you might not have imagined its history and the destruction it has withstood since it was first built in 1930. With this background, there becomes an even greater appreciation for the value of the sustainable marine lumber used in its latest restoration project.

A 1,000 Foot Long Wooden Drawbridge

The Ponquogue Bridge began as a 1,000 foot long wooden drawbridge. Over the years, a lack of proper maintenance contributed to significant rotting of its wood. This ultimately resulted in the reduction of its weight limit in 1976 from 15 tons to eight tons. Years before that, there had been considerable discussion between the United States Coast Guard and the local municipalities (i.e.,  the Town of Southampton and Suffolk County where Sag Harbor is located) on how to improve the bridge.  By 1977, Suffolk County put forth an application for a new bridge to be built 300 feet from the original structure at a cost of $6 million. The building permit was denied because the project would have negatively impacted 3.5 acres of wetlands. Subsequently, in 1980, a new plan was submitted which would come in at a higher cost of $14 million, but would affect a reduced area of 1.5 acres of wetlands. This too and other designs were deemed unacceptable. It wasn’t until 1982 that the Coast Guard finally approved a plan for a new bridge to be constructed 150 feet from the old Ponquoque Bridge structure. During the course of its construction, in 1985, a145-foot, 90-ton girder valued at $29,000, being transported on a crane for part of the bridge’s construction, fell 30 feet onto a barge, splitting in half.  Ultimately, the bridge was constructed, but that incident paled in comparison to damage the bridge would sustain at the hands of two natural disasters.

In 1986, the County replaced the timber bridge with a reinforced concrete bridge that provided more vertical clearance for boat traffic. The timber from portions of the bridge piers were repurposed for fishing piers, a diving pier and a boat launch.  Then, in 2011, Hurricane Irene hit Long Island, causing substantial damage. It was followed by Super Storm Sandy in 2012. With winds of over 100 mph and tides 14 feet above normal heights, Sandy struck a devastating blow to the bridge. This prompted new discussion about its fate. Initial consideration was given to tearing down the bridge, but public outcry and further consideration prevailed based on the significance of the bridge both from a historical and community value standpoint, but also for its importance to the marine ecosystem underneath and around it. Multiple meetings with many concerned environmentalists, divers and community activists led to the decision to restore the bridge. A new restoration plan developed by the Town in conjunction with the Federal Emergency Management Agency (FEMA) and the local community ensued. After FEMA funding was secured, the $1.9 million construction project began in October 2017 and was completed in 2018. A key component of the new bridge design and construction was the use of sustainable marine lumber.

Sustainable Marine Lumber

For marine environments, sustainable marine lumber offers a strong value proposition. It supports the guidelines provided by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce as put forth in their Coastal Nonpoint Pollution Control Program. Its features are also aligned with the technical guidance offered by the Permanent International Commission for the Navigation Congresses (PIANC) relating to sustainable design, construction and management of ports, marinas and related structures.  Specifically, PIANC guidance focuses on preventing hazardous chemicals from entering the water, materials degrading and entering the water, and structures interfering with live habitats and ecosystems under and around a marine structure. Sustainable marine lumber meets these and other important performance criteria.

Sustainable marine lumber is responsibly harvested from forests that are carefully managed from an environmental perspective. Many suppliers of sustainable marine lumber provide products that are Forest Stewardship Council® (FSC ® C117772) Certified indicative of their having been harvested from responsibly managed forests. They are fully aligned with the principles of environmentally sound construction and “engineering with nature.”  If you look at premium Ipe, also known as Brazilian Walnut, the marine lumber used in the Ponquoque Bridge restoration project, the sustainability aspects of this hardwood is evident.

Ipe (Brazilian Walnut)

Ipe has properties that made it the optimum material for the Ponquogue Bridge project. It is extremely strong, durable and dense – twice as dense as most woods and five times harder. Able to withstand heavy pressure, Ipe has a hardness measurement of upwards of 3,500 which is over 2.5 times the hardness of oak, placing it at the top of the Janka rating.  It is also naturally resistant and without any chemical treatment, is impenetrable to insects, including termites. Ipe has proven to remain naturally resistant to insects and marine borers for 15 years which far exceeds any other wood’s ability. Its density also contributes to its water resistant, making it slip-resistant. This feature, along with its Class “A” Fire rating from the National Fire Protection Association (NFPA) helps reduce slip and fall and fire related risks and exposures.

Unlike other wood specified for marine projects, Ipe requires minimal maintenance or the use of hazardous, toxic chemicals. Maintaining its warm red and brown hue requires cleaning with a wood cleaner and an annual UV protection coating. Because of its high density grain and natural oils, it is almost completely impervious to rotting, mold and fungus growth.  With its low maintenance and lifespan of between 50 and 75 years, Ipe delivers a strong return on investment, far greater than other construction materials including composites, concrete, and softwoods.

In addition to Ipe, another widely-specified hardwood used in marine projects is Greenheart (Sipiri). It too possesses outstanding strength and durability, is pest and marine borer resistant and immune to rot, mold, algae and fungi growth. It also holds a NFPA Class “A” Fire Rating. Among its specifications are: an air dried density (12 percent) of 970 kg/m3, bending strength (at 12 percent) of 240 N/mm², modulus of elasticity (at 12 percent) of 24500 N/mm², compression parallel to grain of 89.9 N/mm² and crushing strength (at 12 percent) of 98 N/mm² 

The Bridge Restoration Project

Leading the Ponquogue Bridge project were the engineering design group of L.K. McLean Associates, P.C. (Brookhaven, NY) and the marine construction/engineering firm of Chesterfield Associates (Westhampton Beach, NY and Westport, ME). The project involved the reconstruction of the south side of the old bridge, and redesign of the north side as an additional 60 foot long fishing pier that encompassed flow-through grating to accommodate the rise and fall of storm tides and prevent future damage.

The project began with the design, survey, and securing of environmental permits (i.e., New York State Department of Conservation, U.S. Army Corps of Engineers, and New York Department of State) for the partial demolition and reconstruction of the Old Ponquogue Bridge and piers. Twenty four pile bents were evaluated and rehabilitated across both the north and south piers. The actual restoration encompassed the replacement or rehabilitation of existing timber pier piles and replacement of horizontal wales, longitudinal cross bracing, transverse cross bracing, riders, and stringers.

The first phase of the project involved Chesterfield Associates’ collaring of an estimated 48 of the wood pilings supporting the former bridge.  The pier, which lies on the south side of the bridge and is used primarily by divers, juts out into the Shinnecock Bay and is longer than the northern pier which serves as a fishing pier and was shortened by an estimated 300 feet in the project. The project components included: a sustainable deck and handrail, new bulkheads, and recreational access ramps. Three truckloads of Americans with Disabilities Act (ADA) compliant Ipe lumber for the sustainable deck and handrail were provided by Evergreen Forest Products, Inc. (Wading River, NY).

Protecting the Ecosystem

The use of Ipe marine lumber in key components of the restored Ponquogue Bridge, along with the project’s design, contributed to its eco-friendly status both from a protecting the water  standpoint and the protection of the area’s marine ecosystem. The bridge’s pilings are home to anemones and serve as a nursery for young striped bass and black fish, as well as a habitat for tropical fish (e.g., scamp, snowy grouper, spotfin butterflyfish, roughtail stingray, etc.) that arrive via the Gulf Stream through the incoming tide of the Shinnecock Inlet. The bridge infrastructure also serves as a place for seasweeds, barnacles, inverts, sulfer and red beard sponges, and tunicates to attach to which, in turn, provide food and shelter for other marine organisms, small fish, crabs, mussels and shrimp. Helping to support this ecosystem with sustainable marine projects like the Ponquogue Bridge project featuring a wood like Ipe  is why sustainable marine lumbers are gaining broader application and respect across the engineering and design community.

Richard Zimmerman, Jr. is Sales Manager at Evergreen Forest Products, Inc.