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In this edition, we follow Casey Pantaleo, PE, a licensed Professional Engineer and Senior Project Manager on the Engineering Services team as he performs one of his highly specialized roles: dam inspection. Casey meets the New Jersey Department of Environmental Protection (NJDEP)’s criteria for a “qualified engineer,” meaning he is licensed in New Jersey, has more than a decade of relevant experience in dam design, construction, operation, and evaluation, and possesses a deep understanding of the potential causes and consequences of dam failures. He routinely conducts detailed inspections to help ensure the safety and stability of dams across New Jersey and throughout the Northeast. These structures, which play crucial roles in flood control, water supply, and recreation, require routine maintenance and monitoring to protect downstream communities and preserve infrastructure integrity. Spend a day with Casey and you’ll quickly realize that dam safety inspection is anything but routine—it’s equal parts technical expertise, historical context, and regulatory navigation, along with a good pair of waterproof boots. Inspection, Planning & Records Review Before heading into the field, the inspection process begins with reviewing the dam’s existing documentation; the scope of that review depends on the type of inspection being conducted. For a Formal Inspection, the process requires an in-depth review of all available records on the dam. This typically takes place in person at the NJDEP Bureau of Dam Safety office and should be completed prior to the field visit. For a Regular Inspection, the inspector reviews the most recent inspection report, the dam’s Emergency Action Plan (EAP), and the Operation and Maintenance (O&M) Manual. This step is essential for understanding the dam’s history, known concerns, and any previous recommendations or repairs. Both inspection types involve a detailed on-site visual examination of the dam. The Bureau of Dam Safety provides a standardized inspection checklist that guides this process. The checklist includes specific criteria for earthen embankments, concrete/masonry dams, and their spillway structures. “For earthen embankment dams, we assess the overall alignment, crest, upstream and downstream slopes, and dam abutments,” explains Casey. “We’re looking for signs of settlement, depressions, slope instability, seepage, and other indicators of distress.” For concrete dams, inspectors evaluate the upstream and downstream faces, crest, foundation, abutments, and any interior galleries. The key concerns here are material condition, cracking, seepage, and structural movement. The spillway, which is often inspected last, requires identification of all structures associated with overflow and release. Depending on the dam’s configuration, this may include primary, secondary, or emergency spillways. Components typically observed include:
Welcome to our “A Day in the Life” blog series, where we explore the diverse expertise and everyday experiences of the professionals who power Princeton Hydro’s mission. In this edition, we follow Casey Pantaleo, PE, a licensed Professional Engineer and Senior Project Manager on the Engineering Services team as he performs one of his highly specialized roles: dam inspection.
Casey meets the New Jersey Department of Environmental Protection (NJDEP)’s criteria for a “qualified engineer,” meaning he is licensed in New Jersey, has more than a decade of relevant experience in dam design, construction, operation, and evaluation, and possesses a deep understanding of the potential causes and consequences of dam failures. He routinely conducts detailed inspections to help ensure the safety and stability of dams across New Jersey and throughout the Northeast.
These structures, which play crucial roles in flood control, water supply, and recreation, require routine maintenance and monitoring to protect downstream communities and preserve infrastructure integrity.
Spend a day with Casey and you’ll quickly realize that dam safety inspection is anything but routine—it’s equal parts technical expertise, historical context, and regulatory navigation, along with a good pair of waterproof boots.
Before heading into the field, the inspection process begins with reviewing the dam’s existing documentation; the scope of that review depends on the type of inspection being conducted.
For a Formal Inspection, the process requires an in-depth review of all available records on the dam. This typically takes place in person at the NJDEP Bureau of Dam Safety office and should be completed prior to the field visit.
For a Regular Inspection, the inspector reviews the most recent inspection report, the dam’s Emergency Action Plan (EAP), and the Operation and Maintenance (O&M) Manual. This step is essential for understanding the dam’s history, known concerns, and any previous recommendations or repairs.
Both inspection types involve a detailed on-site visual examination of the dam. The Bureau of Dam Safety provides a standardized inspection checklist that guides this process. The checklist includes specific criteria for earthen embankments, concrete/masonry dams, and their spillway structures.
“For earthen embankment dams, we assess the overall alignment, crest, upstream and downstream slopes, and dam abutments,” explains Casey. “We’re looking for signs of settlement, depressions, slope instability, seepage, and other indicators of distress.”
For concrete dams, inspectors evaluate the upstream and downstream faces, crest, foundation, abutments, and any interior galleries. The key concerns here are material condition, cracking, seepage, and structural movement.
The spillway, which is often inspected last, requires identification of all structures associated with overflow and release. Depending on the dam’s configuration, this may include primary, secondary, or emergency spillways.
Components typically observed include:
“Every dam is different,” Casey adds. “Not all structures have every component listed on the checklist, so part of our job is tailoring the inspection to the specific site configuration.”
The Formal Inspections checklist also includes a review and description of previous engineering studies and analyses, which ensures the dam continues to meet regulatory requirements. These formal evaluations are required every six years for Class I (high hazard) dams, and every ten years for Class II (significant hazard) dams.
All findings from both the field inspection and records review are compiled into a detailed inspection report, which includes photographic documentation and a formal condition rating:
The report also outlines a compliance schedule, proposing timelines for maintenance work, additional studies, or other corrective actions. Once complete, the report is signed and sealed by a licensed Professional Engineer (PE) and submitted to both the client and the Bureau of Dam Safety.
With the planning and records review process complete, Casey prepares for the physical site visit. Dam inspections often require a full day in the field, so preparation is key.
The first step before heading to the site is preparing an Activity Hazards Analysis (AHA). This document outlines the specific activities planned during the inspection, identifies potential hazards associated with each task, and defines the control measures used to eliminate or reduce risk. The AHA also includes the location of the nearest hospital or urgent care facility in case of injury.
Common hazards associated with dam inspections include slips, trips, and falls, insect nests, poison ivy, working near water, and occasionally, working on or near active roadways. Seasonal risks are also considered, such as the potential for heat illnesses during the summer months or cold-related injuries in the winter.
With safety protocols in place, Casey reviews the inspection schedule, checks the weather forecast, prints site maps, and gathers all the necessary personal protective equipment—waders, hard hat, and high-visibility vest—along with essential tools like a tape measure, measuring wheel, tile probe, field notebook, and camera.
Each tool plays a specific role. The tape measure is used for small-scale assessments, such as measuring cracks or depressions. The measuring wheel helps determine distances between notable features onsite. The tile probe allows Casey to gauge the density and consistency of embankment soils and to investigate for voids in concrete structures. It also comes in handy for checking the depth of animal burrows or the extent of subsurface voids within the dam.
“Having the right measuring tools is absolutely essential,” Casey explains. “We aim to collect the most detailed measurements possible so future inspections can determine whether a condition is getting worse. We also try to anticipate every potential hazard and ensure we have everything we might need before leaving the office. Sometimes we’re hiking through thick brush to reach a spillway or crawling into an outlet conduit—so having a solid plan and the right gear isn’t just helpful, it’s critical.”
Today’s inspection takes place at Assunpink Dam #6, an earth embankment dam located in Robbinsville Township, Mercer County, New Jersey. Built in 1975, the dam is part of a flood control system designed to reduce risks along Assunpink Creek. The structure stands 31 feet high and stretches 2,500 feet long, with a total storage capacity of 12,653 acre-feet. It features a concrete spillway and an upstream water control structure. Owned by the New Jersey Division of Fish & Wildlife, the dam is regulated by the state and classified as a high-hazard structure—meaning its failure could result in significant downstream impacts, making regular inspections essential.
To begin the inspection, Casey walks the full length of the embankment, conducting a detailed visual assessment. He looks for telltale warning signs: animal burrows, seepage, erosion, settlement, slope instability, and woody vegetation that could damage the dam face or block visibility during future inspections. One of the most common and problematic issues he encounters is overgrown vegetation, which can significantly hinder the ability to properly evaluate the structure. Keeping the dam clear is critical for spotting early warning signs and maintaining long-term safety.
“Each dam tells its own story,” Casey explains. “Some may show signs of movement, others are perfectly stable. One site might have seepage issues, while another remains completely dry. It all depends on the structure and how it’s aged.”
He carefully inspects the embankment and associated structures for signs of movement, depressions, sloughing, cracking, and uncontrolled seepage, any of which could indicate an underlying issue that requires remediation.
“We follow a standard checklist during every inspection, but each dam is unique,” he adds. “Part of the job is understanding how these systems were built—some decades or even over a century ago—and how they’ve changed over time.”
After completing the full inspection, including the downstream toe, abutments, and emergency spillway, Casey wraps up his field notes, double-checks measurements, and ensures that all required photos have been captured. Before leaving the site, he often debriefs with the site representative, noting any immediate maintenance needs and outlining the next steps in the reporting process.
Back in the office, Casey begins transcribing his notes into a formal inspection report. He uploads and labels photos, updates GIS data where applicable, and reviews the dam’s historical inspection records to identify long-term trends or recurring issues. These records often help tell a broader story about the structure’s condition over time, highlighting vegetation growth, erosion patterns, or the effectiveness of past repairs.
Safety is always the top priority. If the inspection reveals anything that could pose an immediate risk to people or property downstream, such as uncontrolled seepage, excessive settlement, or slope instability, Casey contacts the dam owner and the NJDEP right away to recommend prompt action. Beyond urgent concerns, the inspection report also includes recommendations for routine maintenance and identifies any outdated analyses or studies that should be updated.
In many cases, the findings involve standard upkeep: clearing overgrown vegetation, reseeding disturbed areas, monitoring minor cracks or depressions, or maintaining access to critical features. One frequently emphasized point is the importance of operating the dam’s low-level outlet, if one is present, on a regular basis. Doing so helps ensure the outlet remains free of sediment or debris and functions properly in an emergency when water levels need to be lowered quickly.
New Jersey is home to more than 1,700 dams, according to data from NJDEP Bureau of Dam Safety. These regulated structures range from low-hazard to high-hazard classifications, the latter being dams whose failure could result in significant property damage or loss of life. Regular inspections are not only a regulatory requirement, but a frontline defense against catastrophic failure. They help identify small problems before they become serious, support safe operation, and guide critical maintenance and repair decisions that protect both people and ecosystems.
“Dam inspection doesn’t always get the spotlight, but it’s essential,” says Casey. “We’re helping communities prevent disasters before they happen by keeping a close eye on structures that quietly serve very big purposes.”
For more information about New Jersey’s dam infrastructure and safety programs, go here!
Casey Pantaleo, PE has over a decade of experience in the Geotechnical Engineering field and expertise in dam inspection, stormwater infrastructure, and regulatory permitting. He is a licensed Professional Engineer in New Jersey, Pennsylvania, Connecticut, Delaware, Maryland, and New York. He maintains a wide range of professional responsibilities for the firm including subsurface explorations, development of geotechnical laboratory testing programs, shallow and deep foundation analysis and design, settlement evaluation, earth retaining system design, slope stability analyses, and management of geotechnical field operations. He also has extensive experience with stormwater infiltration analysis and testing, as well as performing annual dam inspections in compliance with the NJDEP Division of Dam Safety. He completes regular inspection reports, as well as reviews of O&M Manuals and Emergency Action Plans. He has experience with the design of dams for rehabilitation, preparation of engineering plans, and submission of relevant dam permits.
Casey earned his Master of Science in Civil Engineering with a Geotechnical focus from Rowan University. While at Rowan he performed comprehensive research on the effects of particle morphology in geotechnical testing using discrete element modeling and has several peer reviewed journal and conference publications outlining the results of this research.
Rivers are the lifeblood of ecosystems, weaving through landscapes to connect habitats, sustain biodiversity, and provide vital resources to communities. Yet, rivers around the world are disrupted by outdated dams, weirs, culverts, and other blockages that fragment habitats, block fish migration, and degrade ecological health. The consequences are far-reaching, threatening not only ecosystems but also the communities that depend on healthy rivers.
Research by the European Open Rivers Programme has highlighted both the urgent need for action and the immense potential of dam removal to restore ecosystems, improve biodiversity, and revive natural river connectivity.
Since 2022, Princeton Hydro President and Principal Geoffrey M. Goll, PE, an expert in water resources engineering, has been collaborating with organizations in Portugal to advance shared goals of river restoration and ecosystem revitalization. In October 2024, Mr. Goll traveled to Portugal, where he met with the organizations driving forward the country’s ecosystem restoration efforts and visited the sites of three key projects he has, or is currently collaborating on.
This blog explores those restoration efforts, highlighting how they address the challenges of river fragmentation while establishing a blueprint for future restoration efforts.
One of the most significant examples of these collaborative restoration efforts is the groundbreaking Galaxes Weir Removal project, which set the stage for future initiatives by addressing river fragmentation on Portugal’s Odeleite River.
Galaxes Weir Removal project in Portugal's Algarve Region marked the country’s first civil removal of an obsolete river barrier to benefit migratory fish species. Associação Natureza Portugal in association with World Wildlife Fund Portugal (ANP/WWF), a non-profit NGO dedicated to the conservation of nature and the protection of the planet, reached out to Mr. Goll and Ms. Lisa Hollingsworth-Segedy of American Rivers, to undertake this pioneering effort.
Completed in March 2023, the removal of the 2-meter-high Galaxes Weir restored 7.7 kilometers of river connectivity, aiding in the preservation of critical fish species such as the Spanish minnowcarp (Anaecypris hispanica) and the critically endangered European eel (Anguilla anguilla). By improving river flow and ecological conditions, the project also bolstered economically vital fisheries, enhanced recreational opportunities, and supported local tourism, establishing a model for future restoration initiatives. Funding for the Galaxes Weir removal was provided by the European Open Rivers Programme (EORP), a grant-giving organization dedicated to restoring European rivers. The international partnership that brought Mr. Goll and Ms. Hollingsworh-Segedy into the fold was facilitated by connections made through the World Fish Migration Foundation. He and Ms. Hollingsworth-Segedy were asked to provide guidance on the de-construction of this concrete structure.
The success of the Galaxes Weir Removal project highlights the importance of both engineering knowledge and techniques, as well as community engagement. By involving local communities throughout the process, the project fostered a sense of shared responsibility and ensured that the ecological and cultural value of the river was preserved. It also underscored the benefits of dam removal as a swift and effective strategy to enhance biodiversity and promote sustainable river management.
Building on the success of the Galaxes Weir removal, the ANP/WWF team expanded its efforts to Santarém, Portugal, northeast of Lisbon, on the Perofilho Stream, a tributary of the Tejo River. The Perofilho Weir, a 2-meter-high concrete barrier, fragmented habitats and disrupted the natural flow of the stream. The National Authority for Nature and Forests Conservation (ICNF) identified the Galaxes Weir as one of the obsolete barriers to be removed to improve fish and overall biodiversity in the area and restore fluvial connectivity.
This restoration project, initiated in 2023, was led by ANP/WWF in collaboration with SOS Animal (weir owner) and the Santarém Municipal Council (local government). Mr. Goll was invited to design the removal of the concrete weir, including innovative solutions such as the use of live timber crib walls for stream bank stabilization. He also provided consultation to the onsite construction manager during the removal process and conducted a final site walkthrough following construction, offering recommendations to ensure long-term success.
The Perofilho Weir removal, completed in October 2024, restored 2.2 kilometers of the Perofilho Stream—nearly half its total length—reconnecting it with the Tejo River. This comprehensive restoration project addressed sediment management, habitat rehabilitation, and flood risk reduction, resulting in significant improvements to water quality and ecological health. Key species benefiting from these efforts include the Eurasian otter (Lutra lutra) and the Iberian painted frog (Discoglossus galganoi). Notably, it also enabled the first research into fish species inhabiting the stream.
This milestone project not only revitalized a critical aquatic ecosystem, it also established a blueprint for future river restoration efforts in Portugal and beyond.
During Mr. Goll’s visit to Portugal in October 2024, he toured the Perofilho Weir removal site alongside Maria João Costa, Water Coordinator of ANP/WWF. Together, they participated in a live video event hosted by the World Fish Migration Foundation, celebrating the project’s success. Broadcasted on the Dam Removal Europe YouTube channel, the event highlighted the restoration effort’s impact on biodiversity and river connectivity. If you missed the live broadcast, the recording is available online. Watch now:
The Oeiras River in western Algarve winds through rural landscapes, agricultural zones, and small towns before merging with the Arade River. This intermittent Mediterranean stream supports native and endangered species and serves as a habitat for some of Portugal’s most iconic mammals.
Recognizing the river’s ecological significance, the ICNF identified it as a high-priority conservation area with potential for impactful restoration. In collaboration with the company Somincor, ICNF contracted ANP/WWF to evaluate the removal of nine barriers along the river, beginning with the upstream Horta Fialho Weir.
To complete the proposed work, ANP/WWF is undertaking several activities, including feasibility assessments, local community and stakeholder engagement, and public environmental education. ANP/WWF engaged Princeton Hydro to prepare the design and specifications for the Horta Fialho Weir removal and develop concept designs for the eight (8) additional barriers.
In October 2024, Mr. Goll spent a week in the field alongside ANP/WWF, surveying the Oeiras River and its tributaries, documenting blockages and ecosystem conditions, meeting with local dam owners and community members, and gathering field measurements to inform the designs and specifications.
The removal of the Horta Fialho Weir will reconnect 2.34 kilometers of the river and set the stage for removing the eight additional barriers, which would ultimately restore 143.4 kilometers of river connectivity. This ambitious initiative is expected to significantly enhance the river’s ecological health and improve habitats for native and endangered species, including freshwater mussels (Unio tumidiformis, Anodonta anatina, Unio delphinus), and their host fish (Squalius spp.), the migratory European eel (Anguilla anguilla), the Iberian lynx (Lynx pardinus), and the Eurasian otter (Lutra lutra).
Beyond ecological benefits, the project offers a unique opportunity to raise awareness about the advantages of dam removal and the critical importance of biodiversity conservation across Portugal. The European Open Rivers Programme is funding this landmark restoration effort.
Portugal’s ecosystem restoration projects illustrate the impact of international collaboration and knowledge exchange. By removing barriers, reconnecting habitats, and revitalizing ecosystems, these efforts are paving the way for a healthier future for rivers and the communities that depend on them. Through continued partnerships and mutual support, the journey toward sustainable environmental stewardship remains hopeful and promising.
Building on the success of these initiatives, Mr. Goll and the Princeton Hydro team look forward to continuing their work in Portugal and beyond, offering technical expertise in ecosystem restoration and barrier removal to support similar efforts around the world.
This work would not be possible without the dedication of ANP/WWF, the European Open Rivers Programme, the Dam Removal Europe team, The National Authority for Nature and Forests Conservation, Herman Wanningen, and all the local landowners who were committed to the restoration of the Oeiras River. Their commitment to river restoration and biodiversity conservation serves as an inspiration, demonstrating the transformative power of collaboration and shared vision. We encourage you to click the links provided to learn more about these vital organizations.
Princeton Hydro has successfully designed, permitted, and overseen the removal of over 84 dams to date. Mr. Goll holds a B.S. in Civil Engineering from Rutgers University and a Master of Engineering Management from UW–Madison. His knowledge encompasses water resources and geotechnical engineering, including sediment management, stream and river restoration, stormwater management, green infrastructure, freshwater wetland and coastal marsh design, dam design, and dam removal. He is recognized as a distinguished leader in advancing innovative and effective solutions for river restoration.
Princeton Hydro is excited to announce that the Musconetcong Island Park Project received the New Jersey Future 2024 Smart Growth Award. This project, led by the Musconetcong Watershed Association (MWA), transformed a crumbling, long-abandoned laboratory into a vibrant, accessible riparian park space that provides opportunities for fishing, wading, paddling, and viewing wildlife in Bethlehem Township, NJ.
The site, which once housed a two-story concrete block laboratory used by the Asbury Graphite Mill, had become a hazard after decades of disuse. Located on a quarter-acre island in the Musconetcong River, the building was not only structurally unsound but also in the floodway of the River, posing ongoing risks to the surrounding environment. Through a collaborative, multi-year effort, the abandoned building was demolished, the area was restored, and the island was transformed into a welcoming, accessible space for public enjoyment and recreation.
The image below shows the old stairway, laboratory building, and island space with a white outline depicting the project area:
The Musconetcong Island Park Project represents a successful collaboration among numerous partners. Led by MWA, the project involved National Fish and Wildlife Foundation, the Township of Bethlehem, Harrington Construction, and Princeton Hydro.
Princeton Hydro provided engineering and environmental consulting services for the project. Our scientists and engineers completed all necessary permitting, designed both the conceptual and final restoration plans, and oversaw construction throughout the project.
Funding for the project was secured through three primary sources: New Jersey Green Acres Program, National Park Foundation, and U.S. Fish and Wildlife Service’s Delaware Watershed Conservation Fund. These grants were instrumental in facilitating the transformation of an industrial relic into a thriving park space, balancing the preservation of the river's natural resources with the creation of an accessible community destination.
The two-story concrete block building that once stood on Musconetcong Island was originally the Asbury Graphite Mill laboratory, constructed between 1925 and 1940. It was built on the foundation of a woolen factory that had been destroyed by fire in 1881. The laboratory was used for testing graphite, an inert and non-toxic mineral primarily used for lubrication and other industrial applications. Graphite refining began in Asbury in 1895, when Harry M. Riddle purchased the existing mills and converted them for this specialized purpose.
By the early 1980s, the laboratory was abandoned due to frequent flooding and a lack of modern plumbing. Despite its industrial history, the building had become a safety and environmental concern due to its floodway location and deteriorating condition. In 1999, the laboratory building was donated to the Musconetcong Watershed Association, who then initiated efforts to restore the site and transform it into a valuable public resource.
Today, the island has been transformed into a place where residents and visitors can enjoy the Musconetcong River. With improved access, new stairways, and interpretive signage sharing the history of the area, Musconetcong Island Park is a prime example of how thoughtful design can blend environmental restoration with community-focused development.
“We are honored to have contributed to the transformation of Musconetcong Island Park and proud to see this project recognized with a New Jersey Future Smart Growth Award for its role in enhancing the Musconetcong River Watershed. It reflects our commitment to sustainable design and the power of collaboration in creating lasting, positive impacts for both the environment and the community. It’s truly a win-win — removing an obstruction from the floodway while providing public access to the river,” said Geoffrey M. Goll PE, President of Princeton Hydro.
Since 2002, the New Jersey Future Smart Growth Awards have celebrated the best examples of sustainable planning and development across the state. The Musconetcong Island Park Project exemplifies these values by enhancing public access to nature, improving resilience to flooding, and fostering sustainable recreation opportunities in the heart of Bethlehem Township. The project showcases the importance of balancing environmental restoration with community needs, creating a space where people can connect with nature while preserving and protecting it for future generations.
The 2024 New Jersey Future Smart Growth Awards recognize six outstanding projects that exemplify innovative and sustainable development. This year’s award ceremony and celebration took place yesterday at the New Brunswick Performing Arts Center.
Click here to learn more about the awards and to view the full list of 2024 Smart Growth Award recipients.
MWA is an independent, nonprofit organization dedicated to protecting and improving the quality of the natural and cultural resources of the Musconetcong River and its Watershed. Members of the organization are part of a network of individuals, families, and companies that care about the Musconetcong River and its watershed, and are dedicated to improving the watershed resources through public education and awareness programs, river water quality monitoring, promotion of sustainable land management practices, and community involvement. Click here to learn more.
Princeton Hydro has been working with MWA in the areas of river restoration, dam removal, and engineering consulting since 2003. Explore how the partnership between Princeton Hydro and the MWA led to the historic return of American shad to the Musconetcong River for the first time in over 250 years, revitalizing the ecosystem—read the full story here!
Stormwater runoff is all of the rainfall or snowmelt water that is not absorbed into the ground and instead flows over land. When not managed properly, stormwater runoff causes issues like pollution in our waterways, flooding, and erosion. Stormwater runoff has been cited in multiple studies as a leading cause of water quality impairment to our local lakes and rivers. And, with increasing levels of rainfall from climate change impacts, stormwater management is an especially critical issue for communities all across the U.S.
Stormwater management focuses on reducing runoff and improving water quality through a variety of techniques.
Traditional stormwater management methods include things like storm drains, retention ponds, and culverts. Green stormwater infrastructure uses vegetation, soil, and other natural components to manage stormwater. Green stormwater infrastructure systems mimic natural hydrology to take advantage of interception, evapotranspiration, and infiltration of stormwater runoff at its source. Examples include rain gardens, constructed wetlands, vegetated bioswales, and living shorelines. Many stormwater systems include a combination of grey and green infrastructure management practices.
Stormwater management treatment "trains" combine multiple stormwater management processes in order to prevent pollution and decrease stormwater flow volumes that negatively affect the receiving waterbody.
Thompson Park is a 675-acre recreation area - the largest developed park in the Middlesex County park system - with numerous attractions including playgrounds, ballfields, hiking trails, and a zoo. The zoo is an animal haven that houses over 50 geese and fowl, goats, and approximately 90 deer in a fenced enclosure. The park also features Lake Manalapan.
Within the zoo is a 0.25-acre pond that impounds stormwater runoff from adjacent uplands and two stormwater-fed tributaries to Lake Manalapan and Manalapan Brook. There are three tributaries to the pond with varying levels of erosion. The western tributary contains a headcut that is approximately four feet high. A headcut is created by a sudden down-cutting of the stream bottom. Similar to a miniature waterfall, a headcut slowly migrates upstream and becomes deeper as it progresses. The headcut in the Zoo tributary had destabilized the stream by eroding and incising its channel and banks. Additionally, foraging by Zoo inhabitants had removed most ground cover around the pond and associated tributaries, which also caused erosion.
The bare soil conditions, headcut, and manure from the Zoo animals were contributing sediment, nutrient, and pathogen loading to the Zoo pond and subsequently Lake Manalapan. The Zoo pond drains to an outlet structure, a 24-inch reinforced concrete pipe (RCP), and subsequently to a vegetated swale via a stormwater outlet. A second outlet pipe drains stormwater runoff from an asphalt parking lot which discharges to the vegetated swale.
The shoreline of Lake Manalapan where the vegetated swale drains into the lake was the subject of a previous restoration project during which a diverse suite of native plants was installed; however, the swale was not included in this project and a maintained lawn, which does not adequately filter stormwater runoff or provide any ecosystem services. The swale also had little access to its floodplain where vegetation can help filter non-point source (NPS) pollutants from the Zoo pond and adjacent uplands.
In order to increase channel stability, decrease erosion, improve water quality and ecological function, and reduce the NPS pollutants originating from the Zoo, a stormwater management treatment train was designed and constructed.
Middlesex County Office of Parks and Recreation and Office of Planning, the New Jersey Department of Environmental Protection (NJDEP), South Jersey Resource Conservation and Development Council (SJRC&D), Middlesex County Mosquito Extermination Commission, Freehold Soil Conservation District, Rutgers Cooperative Extension, Enviroscapes and Princeton Hydro worked together to fund, design, permit, and construct the following stormwater management measures:
To see the project elements taking shape and being completed, watch our video:
The project is funded by a Water Quality Restoration 319(h) grant awarded to SJRC&D by the NJDEP for continued implementation of watershed-based measures to reduce NPS pollutant loading and compliance with a total phosphorus (TP) Total Maximum Daily Load (TMDL) established by the NJDEP for Lake Manalapan. The TMDL is a regulatory term in the U.S. Clean Water Act, that identifies the maximum amount of a pollutant (in this case phosphorus) that a waterbody can receive while still meeting water quality standards.
“The South Jersey Resource Conservation and Development Council was pleased to participate in this project. Partnering with these various governmental agencies and private entities to implement on the ground conservation and water quality improvements aligns perfectly with our mission. We are thrilled with the great work done at Thompson Park and look forward to continuing this partnership.”Craig McGee, South Jersey Resource Conservation and Development Council District Manager
“The South Jersey Resource Conservation and Development Council was pleased to participate in this project. Partnering with these various governmental agencies and private entities to implement on the ground conservation and water quality improvements aligns perfectly with our mission. We are thrilled with the great work done at Thompson Park and look forward to continuing this partnership.”
Construction of the stormwater treatment train components began in early August 2021 and was completed by the end of September 2021.
The first step of the stormwater treatment train was to stabilize the tributary to Lake Manalapan and its associated headcut. Streambank stabilization measures included grade modifications to create a gradual stream slope and dynamically stable form with improved habitat features, including riffles and pools, with gravel and cobble substrate. On August 17, grading of the floodplain bench began, the RCP was exposed, and the team started excavation for the lower three steps in the step-pool sequence.
On August 20, the rock grade and step-pool sequence were completed. And, fabric was installed along both sides of the rock-lined channel to increase stream-bank stability. Rock was placed within the pools to cover the edge of the fabric. We are very pleased to report that the newly restored channel held up to two large storm events during the construction process.
Bags of BioChar, a pure carbon charcoal-like substance made from organic material, were installed across the Zoo pond using an anchor and line system. The BioChar bags help to remove TP and other nutrients from the water column and bed sediments of the Zoo pond and subsequently Manalapan Brook Watershed. The team also built, planted and installed a floating wetland island, an effective green infrastructure solution that improves water quality by assimilating and removing excess nutrients that could fuel algae growth.
After conclusion of pipe lighting, excavation of the floodplain bench and installation of scour protection, native perennial vegetation was planted within the floodplain and swale in order to provide sediment deposition and nutrient uptake functions, as well as aquatic food web services and water temperature moderation before flows are discharged to Lake Manalapan. The plantings also enhance and create suitable avian and pollinator species habitat, and greater flora and fauna diversity.
This stormwater treatment train project improves the habitat and water quality of the Manalapan Brook Watershed by addressing NPS pollutants that originate from Thompson Park Zoo. The completed work also supports the Watershed Protection and Restoration Plan for the Manalapan Brook Watershed by reducing TSS and TP loads in compliance with the TMDL. Additionally, the project improves the overall ecosystem by stabilizing eroded streambanks, installing native and biodiverse vegetation, and reducing the quantity of pollutants entering Lake Manalapan.
“Thompson Park Zoo is an excellent model for showcasing a successful and comprehensive approach to stormwater management and watershed restoration through a dynamic multi-stakeholder partnership. We are so proud to be a part of this project and continue to support the Manalapan Brook Watershed Protection Plan through a variety of restoration activities.”Amy McNamara, E.I.T, Princeton Hydro Project Manager and Water Resource Engineer
“Thompson Park Zoo is an excellent model for showcasing a successful and comprehensive approach to stormwater management and watershed restoration through a dynamic multi-stakeholder partnership. We are so proud to be a part of this project and continue to support the Manalapan Brook Watershed Protection Plan through a variety of restoration activities.”
At Princeton Hydro, we are experts in stormwater management; we recognize the numerous benefits of green infrastructure; and we’ve been incorporating green infrastructure into our engineering designs since before the term was regularly used in the stormwater lexicon. Click here to learn more about our stormwater management services.
Just 50 miles southeast of New York City, tucked between two municipalities, sits a 650+ acre tidal salt marsh which spans the shorelines of the South River in densely populated, highly developed Central New Jersey. The South River is the first major tributary of the Raritan River, located 8.3 miles upstream of the Raritan River’s mouth, which drains into Raritan Bay.
The Lower Raritan River and Raritan Bay make up a large part of the core of the NY-NJ Harbor and Estuary Program. Within the Raritan Estuary, the South River wetland ecosystem is one of the largest remaining wetland complexes. While the South River salt marsh ecosystem has been spared from direct development, it has been degraded in quality, and does not provide optimal habitat for wildlife or maximum flood protection for residents. This area is subject to fairly regular tidal flooding (particularly when it occurs simultaneously with a storm) and periodic—generally more severe—flooding during more significant events such as nor’easters and tropical storms. Hurricanes Irene and Sandy caused damage in the Boroughs of Sayreville and South River too.
In 2018, Princeton Hydro and Rutgers University, along with the Lower Raritan Watershed Partnership, Middlesex County, Borough of Sayreville, Borough of South River, NY/NJ Baykeeper, Raritan Riverkeeper, and the Sustainable Raritan River Initiative, secured funding from NFWF’s National Coastal Resilience Fund for the “South River Ecosystem Restoration & Flood Resiliency Enhancement Project.”
The South River Ecosystem Restoration and Flood Resiliency Enhancement Project aims to:
Reduce socioeconomic damages to the Boroughs of South River and Sayreville caused by storm damage, flooding, and sea level rise;
Transform degraded wetlands to high-quality marsh that can reduce flooding and enhance fish & wildlife habitat; and
Engage stakeholders in activities about coastal resilience and ecological health to maximize public outreach in the Raritan River Watershed.
For this 165-acre tidal marsh and transitional forest “eco-park,” the project team is conducting an ecosystem restoration site assessment and design. This phase of the coastal restoration project will result in a permit-ready engineering design plan that stabilizes approximately 2.5 miles of shoreline, reduces flood risk for smaller coastal storms, and enhances breeding and foraging habitat for 10 state-listed threatened and endangered avian species.
This area has experienced repeated flooding, especially during large storms. For example, coastal areas of Sayreville and South River flooded after Hurricane Floyd (1999), Tropical Storm Ernesto (2006), Hurricane Irene (2011), and Hurricane Sandy (2012). Over the last century, there have been several studies and assessments completed for the South River, many of which identify this project area as a priority location for flooding improvements. The following are key reports and studies published about the project area and surrounding communities:
NJ Legislature’s 71st Congress published a report, “Basinwide Water Resource Development Report on the Raritan River Basin” which focused on navigation and flood control for the entire Raritan River Basin. It discussed recommendations for flood control and local storm drainage, setting the stage for future actions.
NJDEP Division of Water Resources published Flood Hazard Reports for the Matchaponix Brook System and Raritan River Basin, which delineated the floodplains in the South River, and its tributaries, the Manalapan Brook and Matchaponix Brook.
USACE New York District released a “Survey Report for Flood Control, Raritan River Basin,” which served as a comprehensive study of the Raritan River Basin and recommended several additional studies. Although the South River was studied, none of the proposed improvements were determined to be economically feasible at that time.
Project area was listed as one of the Nation’s Estuaries of National Significance.
USACE conducted a multi-purpose study of this area. This preliminary investigation identified Federal interest in Hurricane and Storm Damage Reduction and ecosystem restoration along the South River and concluded that a 100-year level of structural protection would be technically and economically feasible.
USACE NYD and NJDEP released a joint draft, “Integrated Feasibility Report and Environmental Impact Statement” for the South River, Raritan River Basin, which focused on “Hurricane & Storm Damage Reduction and Ecosystem Restoration.” Because it was previously determined that there were no widespread flooding problems upstream, the study area was modified to focus on the flood-prone areas within the Boroughs of Sayreville and South River, as well as Old Bridge Township.
Through collaboration with our project partners and following input provided from a virtual stakeholder meeting held in December 2020, Princeton Hydro developed a conceptual design for an eco-park that incorporates habitat enhancement and restoration, and protective measures to reduce impacts from flooding while maximizing public access and utility. Public access includes trails for walking and designated areas for fishing. The eco-park can also be used for additional recreation activities such as bird watching and kayaking.
Highlights of the conceptual design include the following features:
Approximately two miles of trails with overlook areas, connection to fishing access, and a kayak launch.
~3,000 linear feet of living shoreline, located along portions of the Washington Canal and the South River, to provide protection from erosion, reduce the wake and wave action, and provide habitat for aquatic and terrestrial organisms.
~60 acres of enhanced upland forest to provide contiguous habitat areas for resident and migratory fauna.
A tidal channel that will connect to the existing mud flat on the southeastern part of the site and provide tidal flushing to proposed low and high marsh habitats along its banks.
A vegetated berm with a trail atop will extend the length of the site to help mitigate flood risk.
Two nesting platforms for Osprey, a species listed as “Threatened” in NJ
Designated nesting habitat for the Diamondback Terrapin, a species listed as “Special Concern” in NJ
Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of ecological rehabilitation and floodplain management projects. Click here to read about a coastal rehabilitation and resiliency project we completed in New Jersey.
The Dunes at Shoal Harbor, a coastal residential community in Monmouth County, New Jersey, is situated adjacent to both the Raritan Bay and the New York City Ferry channel. In July 2018, Princeton Hydro was contracted to restore this coastal community that was severely impacted by Hurricane Sandy. Today, we are thrilled to report that the shoreline protection design plans have been fully constructed and the project is complete.
In order to protect the coastal community from flooding, a revetment had been constructed on the property many years ago. The revetment, however, was significantly undersized and completely failed during Hurricane Sandy. The community was subjected to direct wave attack and flooding, homes were damaged, beach access was impaired, and the existing site-wide stormwater management basin and outfall was completely destroyed.
The installation of a 15-foot rock revetment (one foot above the 100-year floodplain elevation) constructed with four-foot diameter boulders;
The replacement of a failed elevated timber walkway with a concrete slab-on-grade walkway, restoring portions of the existing bulkhead, clearing invasive plants, and the complete restoration of the failed stormwater basin and outlet; and
The development of natural barriers to reduce the impacts of storm surges and protect the coastal community, including planting stabilizing coastal vegetation to prevent erosion and installing fencing along the dune to facilitate natural dune growth.
During the final walkthrough earlier this month, the Princeton Hydro team captured drone footage of the completed project site. Click below to watch the video:
For more images and background information on this project, check out the following photo gallery and read our original blog post from July 2018:
For more information about Princeton Hydro’s engineering services, go here.
Hydrology is the study of the properties, distribution, and effects of water on the Earth’s surface, in the soil and underlying rocks, and in the atmosphere. The hydrologic cycle includes all of the ways in which water cycles from land to the atmosphere and back. Hydrologists study natural water-related events such as drought, rainfall, stormwater runoff, and floods, as well as how to predict and manage such events. On the application side, hydrology provides basic laws, equations, algorithms, procedures, and modeling of these events.
Hydraulics is the study of the mechanical behavior of water in physical systems. In engineering terms, hydraulics is the analysis of how surface and subsurface waters move from one point to the next, such as calculating the depth of flow in a pipe or open channel. Hydraulic analysis is used to evaluate flow in rivers, streams, stormwater management networks, sewers, and much more.
Combined hydrologic and hydraulic data, tools, and models are used for analyzing the impacts that waterflow - precipitation, stormwater, floods, and severe storms - will have on the existing infrastructure. This information is also used to make future land-use decisions and improvements that will work within the constraints of the hydrologic cycle and won’t exacerbate flooding or cause water quality impairment.
Simply put, hydrologic and hydraulic modeling is an essential component of any effective flood risk management plan.
Eastwick, a low-lying urbanized neighborhood in Southwest Philadelphia, is located in the Schuylkill River Watershed and is almost completely surrounded by water: The Cobbs and Darby creeks to the west, the Delaware River and wetlands to the south, and the Schuylkill River and Mingo Creek to the east. The community is at continual risk of both riverine and coastal flooding, and faces an uncertain future due to sea level rise and riverine flooding exacerbated by climate change.
Princeton Hydro, along with project partners KeystoneConservation and University of Pennsylvania, conducted an analysis of Eastwick, the flood impacts created by the Lower Darby Creek, and the viability of several potential flood mitigation strategies.
Flood mitigation approaches can be structural and nonstructural. Structural mitigation techniques focus on reconstructing landscapes, including building floodwalls/seawalls and installing floodgates/levees. Nonstructural measures work to reduce damage by removing people and property out of risk areas, including zoning, elevating structures, and conducting property buyouts.
For Eastwick, studying stream dynamics is a key component to determining what type of flood mitigation strategies will yield the most success, as well as identifying the approaches that don’t work for this unique area.
Princeton Hydro’s study focused on the key problem areas in Eastwick: the confluence of Darby Creek and Cobbs Creek; a constriction at Hook Road and 84th Street; and the Clearview Landfill, which is part of the Lower Darby Creek Superfund site. Additionally, the study sought to answer questions commonly asked by community members related to flooding conditions, with the main question being: What impact does the landfill have on area flooding?
The built-up landfill is actually much higher than the stream bed, which creates a major disconnection between the floodplain and the stream channel. If the landfill didn’t exist, would the community still be at risk? If we increased the floodplain into the landfill, would that reduce neighborhood flooding?
Princeton Hydro set out to answer these questions by developing riverine flooding models primarily using data from US Army Corps of Engineers (USACE), Federal Emergency Management Agency (FEMA), The National Oceanic and Atmospheric Administration (NOAA), and NOAA's National Weather Service (NWS). FEMA looks at the impacts of 1% storms that are primarily caused by precipitation events as well as coastal storms and storm surge. NOAA looks at the impacts of hurricanes. And, NOAA's NWS estimates sea, lake and overland storm surge heights from hurricanes.
The models used 2D animation to show how the water flows in various scenarios, putting long-held assumptions to the test.
The models looked at several different strategies, including the complete removal of the Clearview Landfill, which many people anticipated would be the silver bullet to the area’s flooding. The modeling revealed, however, that those long-held assumptions were invalid. Although the landfill removal completely alters the flood dynamics, the neighborhood would still flood even if the landfill weren’t there. Additionally, the modeling showed that the landfill is actually acting as a levee for a large portion of the Eastwick community.
Ultimately, the research and modeling helped conclude that for the specific scenarios we studied, altering stream dynamics – a non-structural measure – is not a viable flood mitigation strategy.
The USACE is currently undergoing a study in collaboration with the Philadelphia Water Department to test the feasibility of a levee system (a structural control measure), which would protect the Eastwick community by diverting the flood water. Funding for the study is expected to be approved in the coming year.
There are many studies highlighting flood mitigation strategies, environmental justice, and climate change vulnerability in Eastwick. Princeton Hydro Senior Project Manager and Senior Ecologist, Christiana Pollack CFM, GISP, presented on the flooding in Eastwick at the Consortium for Climate Risk in the Urban Northeast Seminar held at Drexel University. The seminar also featured presentations from Michael Nairn of the University of Pennsylvania Urban Studies Department, Ashley DiCaro of Interface Studios, and Dr. Philip Orton of Stevens Institute of Technology.
For more information about Princeton Hydro’s flood management services, go here.
Walking through a park isn’t always a walk in the park when it comes to conducting stormwater inspections. Our team routinely spots issues in need of attention when inspecting stormwater infrastructure; that’s why inspections are so important.
Princeton Hydro has been conducting stormwater infrastructure inspections for a variety of municipalities in the Mid-Atlantic region for a decade, including the City of Philadelphia. We are in our seventh year of inspections and assessments of stormwater management practices (SMPs) for the Philadelphia Water Department. These SMPs are constructed on both public and private properties throughout the city and our inspections focus on areas served by combined sewers.
Our water resource engineers are responsible for construction oversight, erosion and sediment control, stormwater facilities maintenance inspections, and overall inspection of various types of stormwater infrastructure installation (also known as “Best Management Practices” or BMPs).
Our knowledgeable team members inspect various sites regularly, and for some municipalities, we perform inspections on a weekly basis. Here’s a glimpse into what a day of stormwater inspection looks like:
The inspector starts by making sure they have all their necessary safety equipment and protection. For the purposes of a simple stormwater inspection the Personal Protection Equipment (PPE) required includes a neon safety vest, hard hat, eye protection, long pants, and boots. Depending on the type of inspection, our team may also have to add additional safety gear such as work gloves or ear plugs. It is recommended that inspectors hold CPR/First Aid and OSHA 10 Hour Construction Safety training certificates.
Once they have their gear, our inspection team heads to the site and makes contact with the site superintendent. It’s important to let the superintendent know they’re there so that 1) they aren’t wondering why a random person is perusing their construction site, and 2) in case of an emergency, the superintendent needs to be aware of every person present on the site.
Once they arrive, our team starts by walking the perimeter of the inspection site, making sure that no sediment is leaving the project area. The team is well-versed in the standards of agencies such as the Pennsylvania Department of Environmental Protection, the Pennsylvania Department of Transportation, the New Jersey Department of Environmental Protection, and local County Soil Conservation Districts, among others. These standards and regulations dictate which practices are and are not compliant on the construction site.
After walking the perimeter, the inspection team moves inward, taking notes and photos throughout the walk. They take a detailed look at the infrastructure that has been installed since the last time they inspected, making sure it was correctly installed according to the engineering plans (also called site plans or drainage and utility plans). They also check to see how many inlets were built, how many feet of stormwater pipe were installed, etc.
If something doesn’t look quite right or needs amending, our staff makes recommendations to the municipality regarding BMPs/SMPs and provides suggestions for implementation.
One example of an issue spotted at one of the sites was a stormwater inlet consistently being inundated by sediment. The inlet is directly connected o the subsurface infiltration basin. When sediment falls through the inlet, it goes into the subsurface infiltration bed, which percolates directly into the groundwater. This sediment is extremely difficult to clean out of the subsurface bed, and once it is in the bed, it breaks down and becomes silt, hindering the function of the stormwater basin.
To remedy this issue, our inspection team suggested they install stone around the perimeter of the inlet on three sides. Although this wasn’t in the original plan, the stones will help to catch sediment before entering the inlet, greatly reducing the threat of basin failure.
Once they’ve thoroughly inspected the site, our team debriefs the site superintendent with their findings. They inform the municipality of any issues they found, any inconsistencies with the construction plans, and recommendations on how to alleviate problems. The inspector will also prepare a Daily Field Report, summarizing the findings of the day, supplemented with photos.
In order to conduct these inspections, one must have a keen eye and extensive stormwater background knowledge. Not only do they need to know and understand the engineering behind these infrastructure implementations, they need to also be intimately familiar with the laws and regulations governing them. Without these routine inspections, mistakes in the construction and maintenance of essential stormwater infrastructure would go unnoticed. Even the smallest overlook can have dangerous effects, which is why our inspections team works diligently to make sure that will not happen.
Our team conducts inspections for municipalities and private entities throughout the Northeast. Click here to read about a stormwater utility investigation and feasibility study we completed in the Town of Hammonton, New Jersey.
This two-part blog series showcases our work in the Moodna Creek Watershed in order to explore common methodologies used to estimate flood risk, develop a flood management strategy, and reduce flooding.
As we laid out in Part One of this blog series, the Moodna Creek Watershed, which covers 180 square miles of eastern Orange County, New York, has seen population growth in recent years and has experienced significant flooding from extreme weather events like Hurricane Irene, Tropical Storm Lee, and Hurricane Sandy. Reports indicate that the Moodna Creek Watershed’s flood risk will likely increase as time passes.
Understanding the existing and anticipated conditions for flooding within a watershed is a critical step to reducing risk. Our analysis revealed that flood risk in the Lower Moodna is predominantly driven by high-velocity flows that cause erosion, scouring, and damage to in-stream structures. The second cause of risk is back-flooding due to naturally formed and man-made constrictions within the channel. Other factors that have influenced flood risk within the watershed, include development within the floodplain and poor stormwater management.
Now, let’s take a closer look at a few of the strategies that we recommended for the Lower Moodna Watershed to address these issues and reduce current and future flood risk:
Stormwater is the runoff or excess water caused by precipitation such as rainwater or snowmelt. In urban areas, it flows over sewer gates which often drain into a lake or river. In natural landscapes, plants absorb and utilize stormwater, with the excess draining into local waterways. In developed areas, like the Moodna Creek watershed, challenges arise from high volumes of uncontrolled stormwater runoff. The result is more water in streams and rivers in a shorter amount of time, producing higher peak flows and contributing to flooding issues.
Pollutant loading is also a major issue with uncontrolled stormwater runoff. Population growth and development are major contributors to the amount of pollutants in runoff as well as the volume and rate of runoff. Together, they can cause changes in hydrology and water quality that result in habitat loss, increased flooding, decreased aquatic biological diversity, and increased sedimentation and erosion.
To reduce flood hazards within the watershed, stormwater management is a primary focus and critical first step of the Moodna Creek Watershed Management Plan. The recommended stormwater improvement strategies include:
The project team recommended that stormwater management be required for all projects and that building regulations ensure development does not change the quantity, quality, or timing of run-off from any parcel within the watershed. Recommendations also stressed the importance of stormwater management ordinances focusing on future flood risk as well as addressing the existing flooding issues.
Floodplains are the low-lying areas of land where floodwater periodically spreads when a river or stream overtops its banks. The floodplain provides a valuable function by storing floodwaters, buffering the effect of peak runoff, lessening erosion, and capturing nutrient-laden sediment.
Communities, like the Moodna Creek watershed, can reduce flooding by rehabilitating water conveyance channels to slow down the flow, increasing floodplain storage in order to intercept rainwater closer to where it falls, and creating floodplain benches to store flood water conveyed in the channel. Increasing floodplain storage can be an approach that mimics and enhances the natural functions of the system.
One of the major causes of flooding along the Lower Moodna was the channel’s inability to maintain and hold high volumes of water caused by rain events. During a significant rain event, the Lower Moodna channel tends to swell, and water spills over its banks and into the community causing flooding. One way to resolve this issue is by changing the grading and increasing the size and depth of the floodplain in certain areas to safely store and infiltrate floodwater. The project team identified several additional opportunities to increase floodplain storage throughout the watershed.
One of the primary areas of opportunity was the Storm King Golf Club project site (above). The team analyzed the topography of the golf course to see if directing flow onto the greens would alter the extent and reach of the floodplain thus reducing the potential for flooding along the roadways and properties in the adjacent neighborhoods. Based on LiDAR data, it was estimated that the alteration of 27 acres could increase floodplain storage by 130.5 acre-feet, which is equivalent to approximately 42.5 million gallons per event.
For areas where land preservation is not a financially viable option, but the land is undeveloped, prone to flooding, and offers ecological value that would be impacted by development, the project team recommended a potential Critical Environmental Area (CEA) designation. A CEA designation does not protect land in perpetuity from development, but would trigger environmental reviews for proposed development under the NY State Quality Environmental Review Act. And, the designation provides an additional layer of scrutiny on projects to ensure they will not exacerbate flooding within the watershed or result in an unintentional increase in risk to existing properties and infrastructure.
Conserved riparian areas also generate a range of ecosystem services, in addition to the hazard mitigation benefits they provide. Protected forests, wetlands, and grasslands along rivers and streams can improve water quality, provide habitat to many species, and offer a wide range of recreational opportunities. Given the co-benefits that protected lands provide, there is growing interest in floodplain conservation as a flood damage reduction strategy.
These are just a few of the flood risk reduction strategies we recommended for the Lower Moodna Creek watershed. For a more in-depth look at the proposed flood mitigation strategies and techniques, download a free copy of our Moodna Creek Watershed and Flood Mitigation Assessment presentation.
Revisit part-one of this blog series, which explores some of the concepts and methods used to estimate flood risk for existing conditions in the year 2050 and develop a flood management strategy.
[caption id="attachment_2936" align="aligncenter" width="493"] Ursino Dam on the Elizabeth River in Union County, New Jersey is one of the sites Princeton Hydro inspected for flood control, ensuring the system is providing the level of protection it was designed to deliver.[/caption]
Located 20 miles southwest of New York City, the City of Elizabeth, New Jersey, is situated along the Elizabeth River. For the city's 125,000 residents, living along the river has many benefits, but the benefits are not without flood risk. In order to manage the risk associated with potential flooding, a series of levees and floodwalls were installed along the banks of the Elizabeth River. A levee is an embankment that is constructed to prevent overflow from a river. They are a crucial element for protecting cities from disastrous flooding, and as such they require periodic inspections to ensure that all components are functioning properly.
Princeton Hydro was contracted by the U.S. Army Corps of Engineers, New York District (USACE NYD) to perform rigorous flood control project inspections (i.e., “Periodic Inspections”) for the four levee systems located along the Elizabeth River. For this project, our team inspected over 17,000 linear feet of levee embankment and 2,500 linear feet of floodwall.
Levee systems are comprised of components which collectively provide flood risk management to a defined area. These components can include levees, structural floodwalls, closure gates, pumping stations, culverts, and interior drainage works. These components are interconnected and collectively ensure the protection of development and/or infrastructure that is situated within a floodplain. Failure of just one critical component within a system could constitute an overall system failure. During Hurricane Katrina, for example, dozens of levees were destroyed, leaving the Louisiana coast with billions of dollars in damage and over one thousand lives lost.
Periodic inspections are necessary in order to ensure a levee system will perform as expected. They are also needed to identify deficiencies in the levee, or areas that need monitoring or immediate repair. Critically important maintenance activities include continuously assessing the integrity of the levee system to identify changes over time, collecting information to help inform decisions about future actions, and providing the public with information about the levees on which they rely.
Periodic inspections are extremely comprehensive and include three key steps: data collection, field inspection, and development of a final report.
Prior to conducting field inspections, Princeton Hydro’s engineers evaluated the Elizabeth River levee system's documented design criteria. This evaluation was conducted to assess the ability of each feature and the overall system to function as authorized, and also to identify any potential need to update the system design. Princeton Hydro teamed with HDR to carry out the inspections. A comprehensive review of existing data on operation and maintenance, previous inspections, emergency action plans, and flood fighting records was also performed.
The Princeton Hydro field inspection team consisted of geotechnical, water resource, mechanical, structural, and electrical engineers. Detailed inspections were performed on each segment of each levee system. This included the detailed inspection and documentation of over 17,000 linear feet of levee embankment, over 2,500 linear feet of floodwall, four pumping stations, 29 interior drainage structures, five closure gates, and various other encroachments and facilities. Princeton Hydro identified, evaluated, and rated the state of each of these system elements. As part of this field inspection task, Princeton Hydro utilized a state-of-the-art tablet and GIS technology in order to field-locate inspection points and record item ratings. This digital collection of data helps expedite data processing and ensures higher levels of accuracy.
Princeton Hydro prepared a Periodic Inspection Report for each of the four levee systems inspected, which included the results of the design document review, methods and results of the field inspection, a summary of areas/items of concern, a preliminary engineering assessment of causes of distress or abnormal conditions, and recommendations for remedial actions to address identified concerns. Final report development included briefing the USACE Levee Safety Officer (LSO) on our inspection findings, assigned ratings, and recommendations.
Levee inspections are vital to the longevity of levee systems and the safety of the communities they protect. By providing the municipalities with detailed inspection reports, effective repair and management programs can be designed and implemented efficiently. This helps to ensure the levee systems are providing the level of protection that they were designed to deliver.
Princeton Hydro’s Geoscience and Water Resource Engineering teams perform levee and dam inspections throughout the Mid-Atlantic and New England Regions. For more info, click here.
Brendon Achey provides a wide range of technical skills and services for Princeton Hydro. His responsibilities include: project management, preparation and quality control of technical deliverables, geotechnical investigations and analysis, groundwater hydrology, soil sampling plan design and implementation, and site characterization. He is responsible for managing the daily operations of the AASHTO-accredited and USACE-validated soil testing laboratory. In addition to laboratory testing and analysis, Brendon is responsible for analyzing results in support of geotechnical and stormwater management design evaluations. This may include bearing capacity and settlement analysis of both shallow and deep foundations, retaining wall design, and recommendations for stormwater management practices.
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