Living Shoreline in Ocean County, NJ Voted “Best Green Project”

Photo by Jason Worth

The Iowa Court and South Green Living Shoreline Project in Little Egg Harbor and Tuckerton, NJ, was awarded “Best Green Project” by Engineering News-Record magazine. The project is recognized for its use of innovative techniques to install new features to restore damage from Hurricane Sandy and protect the area from future storms.

In 2012, Superstorm Sandy devastated communities throughout New Jersey and the entire eastern seaboard. Storm resilience, flood mitigation, and shoreline restoration have since become top priorities for coastal communities and low-lying areas.

The Township of Little Egg Harbor, in conjunction with local partners including the Borough of Tuckerton, was the recipient of a $2.13 million Hurricane Sandy Coastal Resiliency Competitive Grant through the National Fish and Wildlife Foundation for a Marsh Restoration and Replenishment project. The grant was secured by New Jersey Future. The purpose of the project was to restore and replenish local marsh, wetlands, and beaches suffering extensive erosion along the shoreline.

T&M Associates, as the Municipal Engineer of Record for the project, oversaw all aspects of the design and implementation. T&M contracted Princeton Hydro to perform sediment sampling/testing and conduct hydrographic surveys, and Arthur Chew Consulting to assist with the feasibility study and design of the dredging project.

The project, which was completed in September 2019, provides long-term protection from erosion and will restore the vegetated shoreline habitats through strategic placement of plants, stone, sand fill, and other structural and organic materials. The living shoreline will help in the areas of storm protection, flood mitigation, and combatting shoreline erosion. The project was a great success for the Little Egg Harbor and Tuckerton communities.

Photo by Jason Worth

Since the restoration of Iowa Court and South Green Street, this living shoreline model has received significant attention and praise, including in the American Council of Engineering Companies of New Jersey 2020 Engineering Excellence Awards; the New Jersey Society of Municipal Engineers 2019 Project of the Year Awards; and, now, this “Best Green Project” award from Engineering News-Record.

“There is growing interest in this approach from municipalities up and down the Jersey Shore. Storm and flood damage is still a pressing threat to hundreds of towns and boroughs, and it is widely accepted that storms like Sandy will only become more frequent due to the effects of climate change,” said Jason Worth, P.E., Group Manager at T&M Associates. “Thankfully, there is hope in innovation and creativity – with new approaches to living shorelines we can breathe life back into devastated beachfront communities and the natural ecosystems that support them.”

Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of coastal rehabilitation projects. To learn more about some of our ecosystem restoration and enhancement services, visit: bit.ly/PHcoastal.

Photo by Jason Worth

Engineering Assessment of West Point’s Lower Cragston Dam

Highland Falls, New York, which is 40 miles north of Manhattan, stretches along the Hudson River and is populated by many lakes and ponds, including the Cragston Lakes (a.k.a. Lower Cragston). For the community’s 4,000 residents, living in an area where water is abundant has many benefits, but the benefits are not without flood risk.

The 9-acre Lower Cragston Lake, the second largest lake in the Highland Falls area,   contains the Lower Cragston Dam, which is owned by the United States Military Academy at West Point and managed through the U.S. Army Corps of Engineers New York District (USACE NYD). According to the Office of the New York State Comptroller, Lower Cragston Dam is classified as a “High Hazard” dam. The dam is approximately 10 feet high and 210 feet long, and consists of an earthen embankment with a concrete core wall, a concrete ogee spillway, and a low level outlet.

In order to ensure safety to the surrounding community and mitigate any potential flood risk associated with the dam’s operations, Princeton Hydro was contracted by the USACE NYD to perform an Engineering Assessment for Lower Cragston Dam. Engineering Assessments and periodic safety inspections are intended to provide an independent review of an existing dam structure to ensure that all components are functioning properly and in compliance with current dam safety regulations.

Princeton Hydro utilized a multidisciplinary approach to perform the Lower Cragston Dam Engineering Assessment, which consisted of:

  • Document Review: In order to understand the site and to develop a proper drilling scope and methodology, our team conducted a thorough review of existing documentation, including historic engineering plans, dam inspection reports, and an Emergency Action Plan.
  • Geotechnical and Geophysical Investigation and Reporting: This is one of the most significant aspects of a dam safety evaluation and is often the most efficient means of obtaining critical subsurface information. The information obtained from these field studies is used to devise safety improvements if determined to be necessary.
  • Bathymetric and Topographic Survey: The bathymetric survey entails the accurate mapping of water depths and the quantification of the amount of accumulated, unconsolidated sediment. The topographic survey looks at the height, depth, size, and location of the dam and surrounding area.
  • Hydrologic & Hydraulic Analysis: This analysis looks at the watershed and spillway structure related to the extent of potential flooding from storm recurrence intervals within the study area. The data helps to evaluate measures that can reduce and mitigate existing and anticipated flood risk.
  • Structural Analysis: Our team utilized various methods, to assess the structural integrity of the dam and to evaluate the internal stresses and stability under usual, unusual, and extreme loading combinations.
  • Seepage & Stability Analysis: Seepage through an earthen dam generally correlates with the reservoir water level of the dam. A careful analysis helps to detect any abnormal seepage issues and associated consequences.
  • Dam Break Analysis: This type of analysis is used to estimate the potential hazards associated with a failure of the dam structure and features.

The geotechnical investigation for the Lower Cragston Dam Engineering Assessment involved performing soil borings and rock coring within the dam embankment, for which Princeton Hydro developed a Drilling Program Plan (DPP) to ensure the activities were performed successfully and safely. The DPP, which also required our team to have a comprehensive understanding of bedrock and surficial geologic formations in the area, was ultimately approved by the USACE Dam Safety Officer and successfully executed in the field. The collected samples were tested at Princeton Hydro’s AASHTO accredited and USACE validated soil laboratory.

Ultimately, the geotechnical investigation and subsequent soil analysis were used to inform the slope stability and seepage analysis. The geotechnical analyses, hydrologic & hydraulic study, structural inspection, bathymetry, and dam break analysis were used to provide USACE and West Point with recommendations for repair options, replacement options, and decommissioning options for the dam.

Engineering Assessments are vital to the longevity of dams and the safety of the communities they protect. By providing detailed analysis, effective repair, and management programs can be designed and implemented efficiently. This helps to ensure dam systems are providing the level of protection they were designed to deliver.

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of dozens of small and large dams. Our Geoscience and Water Resources Engineering teams perform dam inspections and conduct dam feasibility studies throughout the Northeast. For more info, visit: bit.ly/PHEngineering.

After 100 Years, Fish Passage is Restored at Critical Migratory Fish Spawning Grounds in NJ

Photo by the American Littoral SocietyFor over 100 years, the Old Mill Pond Dam in Spring Lake Heights, New Jersey has blocked critical anadromous fish species from reaching optimal spawning habitat. Today, we are thrilled to announce that, thanks to a fish ladder installed by the American Littoral Society (ALS), migratory fish can now scale the dam and access upstream spawning grounds.

The 60-foot-long fish ladder is a device that allows a channel of water to flow through it and is engineered to create both the proper water depth and velocity for fish to navigate through. In this case, it will enable fish to scale the 10-foot-high dam and go deeper into Wreck Pond Brook.

This video from ALS provides an up-close look at the Alaska-Steeppass Fish Ladder and more details about the project:

Re-opening river passage for migratory species improves not only the health of Wreck Pond Brook and its watershed, but it also benefits the overall ecosystem of the Atlantic shoreline and its coastal rivers. It also supports important recreational and commercial species, such as cod, haddock, and striped bass, which leads to a healthier economy.

For over a century, the dam blocked anadromous fish like Alewife and Blueback river herring, from entering the Wreck Pond Brook Watershed. These fish spend most of their lives in the ocean but need freshwater in order to spawn. The Old Mill Pond Dam, an impassable obstruction for these migrating fish, was identified as a key contributor to the decline of Atlantic coast river herring populations. Subsequently, river herring were classified as National Oceanic and Atmospheric Administration (NOAA) Species of Special Concern and identified as requiring Concentrated Conservation Actions.

Design rendering provided by the American Littoral SocietyThe fish ladder, which was funded through the US Fish and Wildlife Service and implemented by ALS along with a variety of project partners, including Princeton Hydro, is one more major step in the ongoing effort to restore critical migratory fish spawning grounds, support a vibrant food web to the area, and rehabilitate Wreck Pond and its watershed.

According to the ALS, “Now, instead of Old Mill Dam acting as the furthest migration destination for Alewife and Blueback river herring, these fish have the ability to navigate up the dam through the fish ladder and utilize roughly an additional mile of optimal spawning habitat. The ALS will add the Old Mill Dam fish ladder and newly accessible spawning habitat into its ongoing river herring monitoring surveys.”

American Littoral Society promotes the study and conservation of marine life and habitat, protects the coast from harm, and empowers others to do the same. Learn more and get involved: littoralsociety.org.

Princeton Hydro has designed, permitted, and overseen solutions for fish passage including the installation of technical and nature-like fishways and the removal of dozens of small and large dams throughout the Northeast. To learn more about our fish passage and dam removal engineering services, visit: bit.ly/DamBarrier.

Images provided by the American Littoral Society. 

Photo by the American Littoral Society