Bulkheads provide a strong barrier to prevent backfill movement and protect waterfront structures. However, a number of issues can lead to bulkhead failure.
Contractors can stabilize supporting soil and seal leaks in bulkhead joints by injecting a polymer grout into the seawall. This holistic approach manages hydrostatic pressure and enhances longevity and stability. Keep reading the article below to learn more about Bulkhead Erosion Control.
Bulkheads are a vital part of erosion control for waterfront properties. They create a strong barrier that stops water and waves from dragging away soil along shorelines and protecting the foundation of buildings and structures like sheds or decks from damage. They also prevent storm surges from pushing sand, silt and debris downstream to the property. When these barriers are eroded, they put buildings and structures at risk, such as the foundations of homes, gas lines, plumbing and electrical systems. They can even interfere with the quality of drinking and bathing water.
Most bulkheads are built of concrete and/or stone. Over time, these structures may begin to break down due to normal aging and wear and tear, water levels, groundwater flow or hydrostatic pressure that can weaken parts of the structure. When this happens, a damaged bulkhead can cause structural damage to the building or structure that is attached, as well as disrupt the natural ecosystem of the surrounding water.
Typically, the first sign of an eroding bulkhead is visible rust, spalling or exposed rebar. If left untreated, these problems can eventually compromise the safety of nearby boats and people. This can cause serious injuries and property damage, and is expensive to repair.
Other signs of a failing bulkhead include rust or horizontal cracks on the water side of the structure, sheathing that has shifted or is pulling away from the walers or tieback rods, or a deteriorating cap. A cap that is no longer able to retain its original shape or is allowing rainwater through may need to be replaced, or helical tiebacks can be used as a minimally invasive alternative.
The best way to prevent erosion is to use “soft” shoreline protection methods that mimic the environment and interact naturally with it rather than imposing an artificial, hard structure on the shoreline. These methods can protect your home, save you money in costly repairs and maintenance, and improve the health of the environment around your home and the waterway.
Detecting Erosion
Bulkheads are man-made structures constructed along coastal areas to control beach erosion and slow large landslides. Also referred to as seawalls or riprap revetments, they’re made of wood pilings, commercially developed vinyl products, concrete or large rocks stacked in vertical alignment. Designed to stop the natural movement of shoreline soil, they’re most commonly used in protected environments to separate fills from the ocean in marina basins and along reclaimed waterfront areas.
While gradual erosion is normal, human influences and specific natural processes speed the process significantly. In addition to erosion from waves and wind, the soils from bluffs and shorelines can be washed away by groundwater flowing down sloped land. This can cause the toe of a bulkhead to slip outward, leading to cracking or collapse. To prevent this, a bluff must be stabilized through various means, including diversion of surface runoff with rain gutter outlets, French drain installation or strategic landscaping.
Among the most common problems with bulkheads is the separation of slab or panel joints. Signs of this include accumulated rock or dirt in the water near the joint during low tide and unusual overwash events. This issue is typically caused by uneven force from unmanaged hydrostatic pressure differentials. Contractors can inject specialized polymers into seawall joints to evenly distribute this pressure, enhancing structural integrity and overall stability.
Another common problem is the deterioration of the toe and berm of a bulkhead due to cumulative stress from speeding boats, excessive wave action or settlement. Indicators of toe and berm damage include a noticeable twisting or rotation of the toe, visible cracks in the concrete and gaps between the toe and dock if you have one. To help keep this from occurring, a berm should be built up with riprap or bags of dry concrete mix and the toe reinforced with a retaining wall on the water side if possible. Additionally, a French drain can be installed to efficiently manage groundwater flow and eliminate excess pressure that would otherwise pull a bulkhead apart.
Remediating Erosion
Bulkheads are a common way to stabilize coastal property, but their construction and continued use can damage nearby beaches and interconnected habitat areas for plants, animals and fish. In addition, erosion puts nearshore homes and buildings at risk of damage to their foundations and the integrity of plumbing, gas and electric systems. Fortunately, several methods and products allow owners to restore coastlines without the negative effects of bulkheads or other seawall structures.
A bulkhead is a manmade structure built along a shoreline to control beach erosion by preventing backfill movement. It can be constructed from a variety of materials, including wood pilings, commercially developed vinyl products, stone or concrete. Many coastal properties rely on bluff and beachfront bulkheads, but recent studies have shown that they are not as effective as previously believed. In fact, they can even cause erosion on the beach that fronts them.
The primary reason for this phenomenon is that beachfront and bluff structures like seawalls, riprap revetments and rock cribs reflect wave energy rather than disperse it. This energy is then re-suspended on the beach, resulting in a domino effect of beach erosion and ultimately causing the bulkhead to erode as well. To avoid this, a soft shore method is required that maintains a natural slope and absorbs wave energy.
One such method is contour wattling, which utilizes wooden stakes and live plant bundles to maintain the stability of the shoreline. It’s a low-cost option that’s ideal for stabilizing high bluffs, as well as moderate slopes along waterways and roadways.
Other shoreline erosion control solutions include vegetative buffers and marsh sills that help to absorb stormwater runoff, slowing its velocity and reducing its damaging impact on coastal bluffs. Another method is the installation of a sand berm, which redirects surface water flow away from the bluff and toward the shoreline.
When a bulkhead is damaged, it can be repaired using environmentally safe polymer injection, which fills and seals the joints in the wall to stop soil erosion. Olshan offers a holistic repair method that addresses structural, water pressure and hydrostatic pressure concerns simultaneously to ensure superior bulkhead performance. By addressing these concerns collectively, our clients save thousands of dollars in costly repairs and rebuilds and protect their properties and wildlife for the long-term.
Repairing Erosion
Bulkheads are a great way to add security to waterfront property. They also reduce the risk of costly accretion that can lead to damage to buildings, docks, boats or other structures. In fact, many states have regulatory agencies that require shoreline protection to minimize dangers, protect the natural ecosystem and maintain the integrity of structures on waterfront properties.
Coastal erosion is inevitable, but it’s possible to prevent or slow it by keeping water away from areas that are vulnerable to damage. One popular method of controlling erosion is the use of rock barriers, such as rip rap. These limestone walls can displace the wave energy that erodes soil, helping to keep beachfront properties safe and dry.
Another effective strategy is the use of vegetation to stabilize slopes and support soils. Native plants, such as salt marsh grasses, can reduce the harshness of bulkhead edges, provide food and shelter for wildlife and help infiltrate storm waters to reduce pollutants. Another low-cost option is to use rolled erosion control products, such as SOXX, to stabilize slopes and prevent soil loss.
BORDER & TOE FAILURE
Over time, speeding boat traffic and heavy wave action can cause the toe of a seawall to deteriorate and lose contact with the bottom of a berm or slip outward. Toe and berm failure may be corrected by adding bags of concrete mix to the toe or by rebuilding the berm using rip rap. In severe cases, supplemental helical tiebacks and additional pilings may be needed to support the toe.
CORROSION & CRACKS
Corrosion of metals, including steel used in bulkheads, occurs when moisture seeps into the surface and forces it to degrade. This can cause rust marks and horizontal or vertical cracks in the bulkhead panels. In addition, hydrostatic pressure (the force of a fluid due to gravity) can weaken parts of a bulkhead. Modern crack repair techniques can be highly effective, especially if the bulkhead has adequate drainage to relieve hydrostatic pressure.
Premature bulkhead failure is a common issue that can be prevented by ensuring the quality of construction and maintenance. Inspect bulkheads regularly, particularly after heavy rains or storm surges. Be sure to follow local idle speed boating rules and encourage your neighbors to do the same.