When monitoring and managing the health of a lake or pond, dissolved oxygen is one of the most important indicators of water quality. Dissolved oxygen refers to the level of free, non-compound oxygen present in water. It is an important parameter in assessing water quality because of its influence on the organisms living within a body of water; the vast majority of aquatic life needs sufficient amounts of oxygen dissolved in water in order to survive.
Pollutants, the decomposition of invasive aquatic weed growth, and algae blooms significantly reduce dissolved oxygen. The purpose of aeration in lake management is to increase the concentrations of dissolved oxygen in the water. Aeration systems achieve these water quality improvements by helping prevent stagnation of water, increasing circulation, disrupting thermal stratification which provides “through-column” mixing, and minimizes the occurrence of harmful algal blooms (HABs).
Princeton Hydro has been working with the Lake Hopatcong Commission and Lake Hopatcong Foundation to implement several projects aimed at reducing the impacts of HABs in Lake Hopatcong, including the installation of three innovative aeration systems in different areas of the lake. Funding for these projects have come from a NJ Department of Environmental Protection Water Quality Restoration HAB grant awarded to the Commission in 2020, with additional funding and support coming from the Foundation, Morris and Sussex Counties, and four municipalities that surround Lake Hopatcong.
Air Curtain Aeration System
Our team completed the installation of an air curtain system at Shore Hills Country Club in Roxbury Township in early November 2020. The system produces a wall of bubbles that provide the kinetic energy to push and deflect away floating cyanobacteria and other toxins trying to enter the waterway. Installed near the shoreline, the air curtain increases the movement of the water, making it more difficult for floating debris, pollutants, and HABs to accumulate near the shore and in nearby shallow water areas.
Nanobubble Aeration System
Nanobubbles are extremely small gas bubbles that have several unique physical properties that make them very different from normal bubbles. Nanobubble aerators directly saturate the water with significantly more oxygen than traditional water aeration systems. These systems produce ultra-fine bubbles that are nearly invisible to the human eye. Unlike “traditional” aeration systems that push air bubbles to the surface in order to circulate the water and increase the dissolved oxygen levels, nanobubbles are so small that they remain within the water column for an extended period of time, directly oxygenating the water. Our team is scheduled to complete a nanobubble system install for Lake Hopatcong in the Spring of 2021.
Nanobubble Aeration System with Ozone
At Lake Hopatcong’s Lake Forest Yacht Club in Jefferson Township, our team installed a Nanobubble System with Ozone, which was completed in November 2020. This system generates ultrafine microbubbles (nanobubbles) containing ozone, which is used to disinfect water supplies and works to break down organic material in the water. These nanobubbles harness the unique biocidal power of ozone and place it into a safe delivery mechanism that is highly effective but also ensures human and environmental safety. The resulting ozone nanobubbles eliminate a wide range of polluting chemicals as well as herbicides, pesticides, and microbial toxins, which are all known causes of HABs.
The nanobubble technology is a relatively new strategy for preventing cyanobacteria blooms. Evaluation of the air curtain and both nanobubble systems in controlling and minimizing HABs in Lake Hopatcong will begin in Spring 2021. Our team will closely monitor the effectiveness throughout the 2021 season and provide detailed reports of our findings. Stay tuned for more info!
Increasing the dissolved oxygen levels in a pond or lake provides many benefits including improved water quality, healthier fish and plants, more efficient filtration, and reduced nuisance algae growth. Princeton Hydro has installed numerous aerations systems in waterbodies throughout the northeast. Contact us to determine if aeration is the right solution for your pond or lake: PHydro/LakeManagement.
March 2, 2021 is the deadline for New Jersey’s municipalities to comply with the new stormwater management ordinances laid out in the New Jersey Stormwater Management Rule (N.J.A.C. 7:8).
The New Jersey Department of Environmental Protection (NJDEP) revised the rule last year to now require construction projects to include green infrastructure in order to meet the three performance criteria that NJDEP sets forth for stormwater management. The new rule gives local governments an opening to revise their existing stormwater management ordinances to better manage flooding and improve compromised water quality.
The rule defines green infrastructure as, “a stormwater management measure that manages stormwater close to its source by: treating stormwater runoff through infiltration into subsoil; treating stormwater runoff through filtration by vegetation or soil; or storing stormwater runoff for reuse.”
The pre-existing rule required that major developments incorporate nonstructural stormwater management BMPs/strategies to the “maximum extent practicable” to meet their criteria. The amended rule not only gives specific suggestions for the kind of BMPs it’s looking for by adding a definition of green infrastructure, but it also makes those BMPs/strategies a requirement for compliance with the rule’s minimum standards. Also included in the rule are tables outlining the application of each type of stormwater BMP.
Another update to the rule is that motor vehicle surfaces are now incorporated into the definition of major development. The amended rule requires these motor vehicle surfaces to have 80% total suspended solids (TSS) removal in order to maintain water quality. These surfaces include standard pavement drive/parking areas and gravel and dirt drive/parking areas, according to the rule. However, the rule does not require water quality control for runoff from other impervious surfaces that are not traveled by automobiles, such as rooftops and sidewalks, or other paved walkway areas.
New Jersey municipalities need to comply with the new standards and the ordinances must be in effect by March 2nd, 2021. To make this transition a bit smoother, NJDEP released a revised Model Ordinance in Appendix D of the NJ Stormwater BMP Manual to act as a sample for municipalities to follow when adopting these new regulations.
The Watershed Institute also drafted its own Model Ordinance to help municipalities go beyond the updated rule and strengthen protections to benefit the environment. The Model Ordinance builds on the state’s baseline requirements with the following enhancements:
Reduced threshold definition for major development
Requirement for major developments to treat runoff from all impervious surfaces for water quality
Requirement for stormwater management for minor development over 250-square-feet
Stormwater management for redevelopment
The use of Low Impact Development techniques
Maintenance reporting requirements
At the end of last year, The Watershed Institute held a webinar about the state’s new Green Infrastructure rule. The webinar, attended by 240 people, included three presentations that provided a detailed look at the NJDEP’s rule updates and the steps needed for local governments to comply.
The presentations, given by the following green infrastructure experts, are available to view in full:
At Princeton Hydro, we recognize the benefit of green infrastructure and we’ve been incorporating it into our engineering designs since before the term was regularly used in the stormwater lexicon. We’ve been following the rule amendments very closely, and, last year, we developed the following blog to help folks garner a deeper understanding of green infrastructure, interpret the rule updates, and break down the complexities of the stormwater guidelines:
Princeton Hydro has grown from a small, four-person firm operating out of a living room to a 60+ person business with six office locations in the Northeast and a satellite office in Colorado. Over the last two decades, we’ve restored many miles of rivers, improved water quality in hundreds of ponds and lakes, and enhanced thousands of acres of ecosystems in the Northeast.
This year, we are feeling extra grateful for those who have supported our business and helped us further our mission during these difficult times. As we reflect on 2020 and set our sights on 2021, we have many successes to celebrate. Here’s a look at our top 10 successes of the year:
1. RESTORED FISH PASSAGE ON SIX WATERWAYS
Our team installed one fish ladder and oversaw the removal of five dams in four states. In New York, in partnership with Riverkeeper, Princeton Hydro oversaw the removal of two dams on tributaries to the Hudson River: Strooks Felt Dam on the Quassaick Creek in Newburgh and Barrier #1 on Furnace Brook in Cortlandt. The dams were the first barriers for fish movement upstream from the Hudson River. In Connecticut, the Slocomb Dam along Roaring Brook in South Glastonbury was removed, restoring American eel and trout passage. In Massachusetts, the Horseshoe Mill Pond Dam in Wareham was removed, opening over 3 miles of fish habitat on the Weweantic River, Buzzards Bay’s largest freshwater river. Here, migratory fish can now swim unimpeded from Buzzards Bay to lay their eggs in fresh water upstream for the first time in 200 years. In New Jersey, we led the removal of Warren Hills Dam in Washington, NJ and partnered with the American Littoral Society to install a fish ladder at the Old Mill Pond Dam in Spring Lake Heights, NJ, which allows migratory fish to scale the dam and access spawning grounds that had been blocked-off for over 100 years.
2. LED THE LARGEST APPLICATION OF PHOSLOCK IN THE NORTHEAST ON NEW JERSEY’S LARGEST LAKE
3. DESIGNED AND CONSTRUCTED WETLAND AND SHORELINE RESTORATION PROJECTS
We completed a shoreline restoration project at The Dunes at Shoal Harbor, a coastal residential community along the Jersey Shore that was severely impacted by Hurricane Sandy. In Linden’s Tremley Point neighborhood – another New Jersey community ravaged by Hurricane Sandy – we completed a green infrastructure and floodplain restoration project, the first restoration project to ever be implemented on NJDEP Blue Acres-acquired property. We transformed a densely developed, flood-prone, former industrial site in Bloomfield into a thriving public park with 4.2 acres of wetlands. Each of these three projects helped to restore valuable ecological functions and increase storm resiliency.
4. LAUNCHED A COMMUNITY SCIENCE MONITORING PROJECT FOR THE SCHUYLKILL RIVER
On World Habitat Day, the nonprofit, Schuylkill River Greenways, in partnership with Berks Nature, Bartram’s Garden, The Schuylkill Center for Environmental Education, Stroud Water Research Center, and Princeton Hydro, kicked-off a Water Quality Monitoring Project for the Schuylkill River. This project aims to document the current ecological health of the river and engage a diverse set of river users and residents. As part of the campaign, the team is recruiting “Community Scientists” to conduct Visual Monitoring Assessments. Additionally, the stakeholder team is implementing water quality sampling and monitoring throughout 2021 at locations along the main stem of the Schuylkill River.
5. WELCOMED EIGHT NEW FULL-TIME TEAM MEMBERS
This year, we added eight new full-time staff members and one intern with expertise and qualifications in a variety of fields, all of whom have a passion for water resource management and environmental stewardship. In March, we were thrilled to welcome Dr. Laura Craig to our team as the new Director of Natural Resources. She is an Aquatic Ecologist who has overseen 25 dam removals, co-founded the NJ Dam Removal Partnership, and has 10+ years of experience in river conservation and climate adaptation. Go here to learn about the career opportunities currently available with us.
6. COMPLETED A MAJOR ECOLOGICAL STUDY OF THE HUDSON RIVER
The New Jersey Section of the American Water Resources Association honored Princeton Hydro with the “Excellence in Water Resources: Ecological Restoration Award” for the Linden Blue Acres Floodplain Restoration & Green Infrastructure project. This restored the ecological and floodplain function on former residential properties acquired by the NJDEP Blue Acres Program for the first time. The American Littoral Society and Princeton Hydro received the “Land Ethics Best Large-Scale Project Award” from Bowman’s Hill Wildflower Preserve for the work they did to restore the health and water quality of the Metedeconk River flowing through Ocean County Park in Lakewood, NJ. The Iowa Court and South Green Living Shoreline Project in Little Egg Harbor and Tuckerton, NJ, for which Princeton Hydro lead the sediment sampling/testing and hydrographic survey, received the “2020 Best Green Project Award” from Engineering News-Record.
8. GAVE OVER 20 PRESENTATIONS ON WATERSHED MANAGEMENT & RESILIENCY MEASURES
2020 was a particularly challenging year, but the Princeton Hydro family stood together. With offices spread across the Northeast and collaboration between offices on a daily basis, we were unknowingly prepared for the shift to remote work during an unexpected global pandemic. But, it took more than just working laptops and VPN connections to keep us going. Because of our staff’s motivation and dedication to serving our clients, we were able to not only keep our firm open, but we continued to grow our geographic and service reach.
Thank you for supporting Princeton Hydro and sharing our stories. We truly appreciate each and every one of our clients, partners, and friends. Cheers to a fruitful 2021 and beyond!
Princeton Hydro’s Senior Project Manager and Senior Aquatic Ecologist Chris L. Mikolajczyk, CLM, has been chosen as North American Lake Management Society’s (NALMS) next Board of Directors President-Elect. The President serves a three-year term including one year as President-Elect, one year as President, and one year as Immediate Past-President.
Founded in 1980, NALMS is dedicated to forging partnerships among citizens, scientists and professionals to foster the management and protection of lakes and reservoirs for today and tomorrow. The annual election is an important way for members to provide input into the management of the NALMS. In order to be eligible for a board position, candidates must be nominated by two organization members, be active in the organization, display leadership ability, and be able to accept the duties of office and attend semi-annual board meetings.
“I’m so proud to be a part of NALMS and honored to be chosen as President-Elect of this prestigious organization,” said Chris. “I look forward to working even more closely with the staff, the board, and members to uphold the mission of NALMS and seize the opportunities ahead.”
The Board of Director election results were announced during the NALMS International Symposium, which was held virtually this year. During the virtual symposium, NALMS also revealed the recipients of its annual Achievement Awards. The awards recognize individuals and organizations who have made valuable contributions to the goals of the organization or significant strides in lake management.
This year, the 2020 Leadership and Service Award winner was the Lake Champlain Committee of Burlington, VT. The 2020 Appreciation Award winners include: St. John’s River Water Management District in Palatka, FL; City of San Diego Water Utilities in San Diego, CA; and Water Quality Committee of the Normanoch Association, Inc. in Branchville, NJ.
Big congratulations to all award winners and newly elected Board members!
To see the full 2020 Board of Directors election results, go here. To learn more about the achievement awards and see a complete list of recipients, go here. To learn more about NALMS, go here.
Princeton Hydro is the industry leader in lake restoration and watershed management. We have conducted diagnostic studies and have developed management and restoration plans for over 300 lakes and watersheds throughout the country. This has included work for public and private recreational lakes, major water supply reservoirs, and watershed management initiatives conducted as part of USEPA and/or state funded programs. For more information about our lake management services, click here.
Chris is a CLM and Senior Project Manager in Princeton Hydro’s Aquatic Resources Practice Area and conducts the management, oversight, and coordination of aquatic ecology and water resource projects. He leads green infrastructure and lake restoration projects, performs water quality sampling and investigations, and conducts stormwater quality modeling. Chris has been with Princeton Hydro since 1999 and has studied and managed well over 75 lakes in his career there. Read his full bio here.
A project to increase storm resiliency and reduce flood risk through ecological and floodplain restoration on a New Jersey Department of Environmental Protection (NJDEP) Blue Acres property in Linden, NJ was completed earlier this year. Today, we are thrilled to announce our project has received the “Excellence in Water Resources: Ecological Restoration Award” from the New Jersey Section – American Water Resources Association (NJ-AWRA).
“The Linden Blue Acres Green Infrastructure & Floodplain Restoration is an excellent model for showcasing a successful approach to the enhancement of public lands through a dynamic multidisciplinary, multi-stakeholder partnership,” said Mark Gallagher, Vice President of Princeton Hydro. “We are so proud to have seen this project through to completion and are all the more honored to be recognized by the NJ-AWRA with this prestigious award.”
The NJ-AWRA Excellence Award recognizes projects that demonstrate an innovative and effective approach to water resources management. The projects must embody the mission of the AWRA to advance multidisciplinary water resources education, management and research. The Linden Blue Acres project excelled in these areas, resulting in the successful nomination of the project to receive the award.
The City of Linden, located 13 miles southwest of Manhattan, is a highly urbanized area with a complex mix of residential, commercial, and industrial land uses. Originally settled as farmland on broad marshes, the city has deep roots in industrial production that emerged in the 19th century, and its easily accessible location on the Arthur Kill tidal straight helped fuel this industrial development.
Like other communities in the Arthur Kill Watershed, Linden also suffers severe flooding from heavy rains and storms. Due to a high percentage of impervious cover from houses, roadways, and sidewalks, even small rain events generate a significant amount of stormwater runoff. Tremley Point, a low-lying community of about 275 homes, is particularly prone to backwater flooding because of its low lying landscape position and its proximity to an extensive area of tidal wetlands associated with Marshes Creek, a tributary to the Rahway River.
In 2012, Hurricane Sandy caused widespread destruction to the City of Linden. The City’s Tremley Point neighborhood was especially storm-ravaged; local news outlets reported that a 15-foot tidal surge overtook Tremley Point homes, destroyed roads, and washed up hazardous material such as a 150-gallon diesel tank.
22 properties in Tremley Point were aquired by NJDEP Blue Acres.
To help communities like Tremley Point recover, the NJDEP launched the Blue Acres program under which NJDEP purchases homes from willing sellers at pre-Sandy market values, so residents in areas of repetitive and catastrophic flooding can rebuild their lives outside flood-prone areas. Structures are demolished and the properties are permanently preserved as open space for recreation or conservation purposes.
As part of the NJDEP Blue Acres Program, Princeton Hydro, in collaboration with the City of Linden, Rutgers University, NJDEP, Phillips 66, National Fish and Wildlife Foundation, New Jersey Corporate Wetlands Restoration Partnership, and Enviroscapes, took on one of the first ecological restoration projects within Blue Acres-acquired properties. This project increased storm resiliency by reducing flooding and stormwater runoff by improving the ecological and floodplain function within the Tremley Point properties acquired by the NJDEP Blue Acres Program.
Project partners at present the project to the community in Linden, NJ
Nancy Sadlon, Manager of Public Affairs for Phillips 66-Bayway Refinery, accepted the award on behalf of the project team and said, “Our team not only made possible the first successful implementation of the floodplain restoration on Blue Acres lands but set a precedent on stakeholder engagement; we showed what is possible when all stakeholders are fully engaged and dedicated to the same goal.”
The project included the development and implementation of an on-the-ground natural green infrastructure-focused floodplain enhancement design involving the restoration of native coastal floodplain forest and meadow, as well as floodplain wetlands. The restored area provides natural buffering to storm surge and enhances floodplain functions to capture, infiltrate, store, and slow excess stormwater to reduce the risk of future flood damage. In addition, it restores natural habitat and provides public recreation access on NJDEP Blue Acres property.
Although the planning for this project occurred over many years, the project officially kicked off in December 2018. Engineering design was finalized and permitting submissions were completed in September 2019, and construction commenced in October 2019. The project construction was completed earlier this year.
This project embodies the NJ-AWRA mission as it focuses on restoring a floodplain and enhancing its functions by leveraging the success of the NJDEP Blue Acres buyouts to create even more flood protection for the community. This project also fulfills the NJ-AWRA criteria as several different organizations were involved in bringing it to fruition, including private entities, government agencies, universities, and nonprofit organizations.
July 2020, Post-Construction
July 2020, Post-Construction
Given that this project was the first restoration project to be completed on NJDEP Blue Acres-acquired property, the hope is that it will bring to light other possibilities for restoration work on Blue Acres land. This project can be used as an example for future projects of a similar nature.
We would also like to thank the project funders, whose support made this project possible: The National Fish and Wildlife Foundation, Phillips 66, and the New Jersey Corporate Wetlands Restoration Partnership.
During the award ceremony, which was held virtually, NJ-AWRA also recognized John A. Miller, PE, CFM, CSM with the Peter Homack Award for “his outstanding contributions toward a multidisciplinary understanding and management of water resources in New Jersey.” John previously worked with Princeton Hydro for 15 years as a Water Resources Engineer and now serves as the Mitigation Liaison to the State of New Jersey at the Federal Emergency Management Agency (FEMA). We are so proud of John and all his accomplishments. This award is well deserved and we congratulate him on this honor.
As part of the multi-faceted effort to restore the vital Hudson River ecosystem, the USACE New York District launched the Hudson River Habitat Restoration. Princeton Hydro led the Hudson River Habitat Restoration Integrated Feasibility Study and Environmental Assessment for USACE. For this project, we established and evaluated baseline conditions through data collection and analysis; developed restoration objectives and opportunities; prepared an Environmental Assessment; and designed conceptual restoration plans for eight sites.
This week, Lt. Gen. Scott A. Spellmon, USACE Commanding General and 55th U.S. Army Chief of Engineers, signed the Hudson River Habitat Restoration Ecosystem Restoration Chief’s Report, which represents the completion of the study and makes it eligible for congressional authorization.
As stated in the USACE-issued news release, “The Chief’s Report recommends three individual ecosystem restoration projects including Henry Hudson Park, Schodack Island Park, and Moodna Creek within the 125-mile study area from the Federal Lock and Dam at Troy, NY to the Governor Mario M. Cuomo Bridge. These projects would restore a total of approximately 22.8 acres of tidal wetlands, 8.5 acres of side-channel and wetland complex, and 1,760 linear feet of living shoreline with 0.6 acres of tidal wetlands. The plan would also reconnect 7.8 miles of tributary habitat to the Hudson River through the removal of 3 barriers along Moodna Creek.”
“The signing of this Chief’s Report is a significant milestone for the HRHR Project,” said Col. Matthew Luzzatto, USACE New York District Commander. “This has truly been a team effort and I want to thank our non-federal sponsors, New York State Department of Environmental Conservation and New York State Department of State, and all of our engineers, scientists, and partners at the local, state and federal level for their unwavering support.”
Read the full press release here. And, for more background information on the Feasibility Study and proposed restoration work, check out our original blog post:
The Iowa Court and South Green Living Shoreline Project in Little Egg Harbor and Tuckerton, NJ, was awarded “Best Green Project” by Engineering News-Recordmagazine. 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.
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.
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.
“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.
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.
For 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.
The 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.
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.
Rendering of the shoreline protection design
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.
Princeton Hydro performed a wave attack analysis commensurate with a category three hurricane event and used that data to complete a site design for shoreline protection.
The site design and construction plans included:
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.
These measures will prevent shoreline erosion, protect the community from wave attacks and flooding, and create a stable habitat for native and migratory species.
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: