Fish Passage Restored on the Paulins Kill

A view of where the Columbia Lake Dam used to reside. February 19, 2019. Photo courtesy of Casey Schrading, Staff Engineer, Princeton Hydro

On the Paulins Kill, the 100-year old Columbia Lake Dam has almost been completely removed, and fish passage has been restored!  Since the first cut was executed on the main dam in August, many exciting advances have been made towards restoring the Paulins Kill back to its natural state. Check out the video below, courtesy of the New Jersey Nature Conservancy Volunteer Drone Team. 

Piece by piece, the dam was notched out throughout the fall season and is now completely removed with the exception of the dam apron, the horizontal concrete structure that sits downstream of the dam, and the section of the dam that sits below the riverbed. The part of the dam in the riverbed is now being removed all the way down  to three feet under the ground. The full removal is estimated to be complete by mid-March. In mid-August, the first cut was widened to 80 feet, allowing for better management of high flows during storm events, which had been posing a challenge immediately following the first cut.

In late August, the installation of rock vanes at the Brugler Road Bridge began. Rock vanes are engineered, in-stream structures that help to stabilize a channel while enhancing aquatic habitat and movement.

A generic schematic example of cross vanes, this is not the exact engineering plan for this specific project. Photo courtesy of North Carolina Cooperative Extension.

The rock vanes installed at the Brugler Road Bridge site are cross vanes. Cross vanes consist of a set of boulders angled upstream on a river, with another section of smaller rocks placed upstream. The taller sections of the cross vanes deflect the streamflow away from the banks, decreasing scouring effects. Instead, the flow travels over the rock walls and concentrates down the center of the channel, creating a deep and elongated pool in the middle of the stream.  

Velocities between the notches in the rock vanes were evaluated using a velocity meter in accordance with the design specifications originally proposed. Based on the U.S. Fish and Wildlife Service fish passage design criteria, velocities in the notches could not be greater than 8.25 feet per second. All of the velocity measurements in this rock vane were below the maximum thresholds, ensuring no blockage of fish passage is made through the vanes.

Since the removal of the dam began, vegetative growth from the natural seedbed of the upper impoundment has been observed (see photo below).

In October, scour protection installation commenced at the Warrington Road Bridge site. After the team conducted geotechnical test pits, they discovered that a concrete scour wall that slopes out to the Paulins Kill was present and deep enough to be able to install rock at the necessary depth. They also found that the existing gabions, caged baskets filled with rock or concrete often used to protect against erosion, were intact and could be left in place. The team installed four (4) feet of riprap under and around the bridge in the riverbed and tied it into the existing grade of the banks.

The original notch in the dam was lowered one foot per day starting in mid-December, reducing water surface elevations down to the apron elevation during the month of January.

To accommodate NJ Fish and Wildlife’s request for animal passage under the I-80 bridges, an area of the previously installed riprap on the northwest abutment wall was flattened out and filled in with river cobble. This path will promote wildlife movement under the bridge as opposed to through the existing tunnel.

Currently, rock vanes are being installed under the I-80 bridges specifically to enhance fish passage. These structures vary slightly from the rock vanes at the Brugler Road Bridge site, as they are designed to slow river flow, helping migrating fish travel upstream and traverse a 5-foot elevation difference in the streambed, much like a fish ladder

These rock vanes are more than halfway completed and are on track to be finished in time for fish populations to make full use of them.  The next steps are to finish the demolition of the dam and the construction of the fish passage rock vanes under the I-80 bridges, plant vegetation throughout the upper impoundment, create a recreational trail through the upper impoundment, and plan for fishing and boating access! Stay tuned for more exciting developments on this incredible project.

Thank you to our project partners: The Nature Conservancy, American Rivers, U.S. Fish and Wildlife Service, and NJDEP Division of Fish and Wildlife Service.

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of a dozens of small and large dams in the Northeast. To learn more about our fish passage and dam removal engineering services, visitbit.ly/DamBarrier.

Part Two: Reducing Flood Risk in Moodna Creek Watershed

Photo of Moodna Creek taken from the Forge Hill Road bridge, New Windsor Post Hurricane Irene (Courtesy of Daniel Case via Wikimedia Commons)

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.

Welcome to Part Two: Flood Risk Reduction and Stormwater Management in the Moodna Creek Watershed

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 Management

Damage to Butternut Drive caused when Moodna Creek flooded after Hurricane Irene (Courtesy of Daniel Case via Wikimedia Commons)

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:

  • Minimizing the amount of impervious area within the watershed for new development, and replacing existing impervious surfaces with planter boxes, rain gardens and porous pavement.
  • Utilizing low-impact design measures like bioretention basins and constructed-wetland systems that mimic the role of natural wetlands by temporarily detaining and filtering stormwater.
  • Ensuring the long-term protection and viability of the watershed’s natural wetlands.

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.

Floodplain Storage

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.

Land Preservation & Critical Environmental Area Designation

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.

Two-Part Blog Series: Flood Assessment, Mitigation & Management

For more information about Princeton Hydro’s flood management services, go here: http://bit.ly/PHfloodplain

Employee Spotlight: Meet Our New Team Members

We’re excited to welcome four new members to our team. The addition of this group of talented individuals strengthens our commitment to delivering great service that exceeds our clients’ expectations.

Meet Our New Team Members
Miranda Lepek, EIT, Water Resource Engineer

Miranda is a civil engineer with expertise in grading and stormwater design, CAD drafting, environmental sampling, and construction oversight. Prior to Princeton Hydro, she worked for a small site development firm in Michigan where she developed her drafting skills and facilitated multiple aspects of private and commercial land development projects.

Miranda holds a B.S. in Civil Engineering from the University of Michigan – Ann Arbor. While on study abroad, she contributed to the one of the longest-running native amphibian field studies in New Zealand. In other previous experiences, she worked on major projects including the investigation phases of a Superfund site cleanup in Duluth, MN and a comprehensive sampling operation over 40 miles of the Hudson River near Albany, NY. In her free time, Miranda enjoys hiking, foraging, cooking and art.

Sumantha Prasad, PE, ENV SP, Water Resource Engineer

Sumantha is a Water Resource Engineer with a B.S. in Bioenvironmental Engineering from Rutgers University and a M.S. in Environmental Engineering and Science from Johns Hopkins University. She worked in Maryland for seven years focusing on ecological restoration projects, including stream restoration, wetland creation and enhancement, and stormwater management, and she worked for 3 years with a primary focus on highway hydrology and hydraulics.

In her spare time, she enjoys being a Toastmaster and serves as the Treasurer to a 501(c)3 organization dedicated to creating inclusive housing communities for adults with disabilities. She also enjoys telling terrible puns unapologetically.

Pat Rose, Environmental Scientist

Pat’s interest in aquatics began during a summer course studying at Lake Atitlán, Guatemala as an undergraduate at SUNY Oneonta. After graduation, he spent a year volunteering with AmeriCorps in Knoxville, Tennessee as part of a Water Quality Team. While in Tennessee, Pat spent the majority of his time educating high school students on how to protect and improve local waterways and watersheds as part of the Adopt-A-Watershed program. During his year with AmeriCorps, Pat worked with government organizations to perform biological sampling and erosion monitoring in local streams.

Pat graduated from SUNY Oneonta with a M.S. in Lake Management in December 2018. During his time in graduate school, he created an interim lake management plan for a small reservoir in New York that has had cyanobacterial blooms over the past few years. Pat spent this past summer completing a co-op with an aquatic plant management company in the Pacific Northwest, working primarily with invasive Eurasian and hybrid watermilfoil populations.

Duncan Simpson, Senior Environmental Scientist

For nearly a decade, Duncan has served as an Environmental Scientist/Planner in the Mid-Atlantic Region. His experience includes a wide range of natural resource studies, documentation, and permitting at both the project and program level. He has special expertise in wetlands; Waters of the US delineations; and permitting for stormwater management facilities, stream restoration, and TMDL program projects. He has conducted forest stand delineations; rare, threatened and endangered species consultations; mitigation monitoring; and National Environmental Policy Act (NEPA) documentation.

Duncan holds an M.S in Biology from Towson University and a B.S. in Environmental Science with a Wildlife and Fisheries Conservation Minor from the University of Massachusetts. During his graduate studies, he researched amphibian species found in Delmarva Bays and testing models that predict their presence based on abiotic habitat characteristics. He also served as a student member of the Northeast Partners in Amphibian and Reptile Conservation (NEPARC) steering committee. Duncan is a Professional Wetland Scientist and member of the Society of Wetland Scientists. In his spare time, he enjoys hiking with his dog and learning how to fly fish.

 

Employee Spotlight: Helping Communities Around the World Access Water Resources

We’re Proud to Put the Spotlight on Natalie Rodrigues, Staff Engineer And Engineers Without Borders Co-President

As a staff engineer specializing in water resources, Natalie Rodrigues, EIT, CPESC-IT works on a wide range of projects from stormwater management to ecosystem restoration to dam safety. Outside of the office, Natalie is an active volunteer with Engineers Without Borders (EWB), a nonprofit organization that works to build a better world through engineering projects that aid communities in meeting their basic needs.

EWB volunteers work with communities in the U.S. and throughout the world to find appropriate solutions for their infrastructure needs, including clean water supply; sanitation; sustainable energy; structures like bridges and buildings; and various agriculture essentials from irrigation systems to harvest processing.  Natalie began volunteering for the organization six years ago while attending college at the SUNY College of Environmental Science and Forestry where she earned her Bachelor of Science in Environmental Resources Engineering with a focus in water resources.

Natalie and Lola, a student from the elementary school in Guatemala where Natalie assisted on an EWB project to install a latrine system

Her first big volunteer project, which was done in collaboration with EWB’s Syracuse Professionals Chapter, was designing and building a system of composting latrines for an elementary school in the small town of Las Majadas, Guatemala. Natalie provided assistance on several aspects of the project, including working on a Health and Safety Plan. The completion of this project helped to prevent the spread of disease, as well as treat waste without the need for a constant water supply/sewer system. The long-lasting design also increases the health practices and hygiene of the community, creating a safer place for education.

Natalie also served as secretary of the university’s EWB chapter for two years, then became the Regional Administrator for the Northeast Regional Committee, and is now starting her third year as a Co-President of the region.

In her current role with the regional committee, Natalie helps to provide resources for members and facilitates communication between EWB Headquarters and individual chapters. She assists with various mini-conferences and workshops throughout the region and provides opportunities for members to obtain Professional Development Hours and certifications. She is also a part of the EWB’s Diversity and Inclusion Task Force and the Council of Regional Presidents.

Natalie stands with her 2018 Northeast Regional Committee members at the 2018 National Conference

We’re so proud to have Natalie on our team and truly value the work she does inside and outside the office.

Levee Inspections Along the Elizabeth River

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.

By Brendon Achey, Princeton Hydro’s Lead Geologist; Soils Laboratory Manager; Project Manager

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.

Levee Inspection Process

Periodic inspections are extremely comprehensive and include three key steps: data collection, field inspection, and development of a final report.

Data Collection

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.

Field Inspection

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.

Development of Final Report

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, visit: http://bit.ly/PHEngineering

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.

Two-Part Blog Series: Flood Assessment, Mitigation & Management

In this two part blog series, we showcase our work in the Moodna Creek Watershed in order to explore some of the concepts and methods used to estimate flood risk for existing conditions and the year 2050 and develop a flood management strategy (Part One), and traditional engineering and natural systems solutions used to manage and reduce flood risk (Part Two).

Part One: Flood Assessment & Mitigation Analysis in the Moodna Creek Watershed

The greater Moodna Creek watershed covers 180 square miles of eastern Orange County, NY. The watershed includes 22 municipalities and hundreds of streams before joining the Hudson River. This region has seen tremendous growth in recent years with the expansion of regional transit networks and critical infrastructure.

The Moodna Creek watershed can be split into two sub-basins — the Upper Moodna Creek and the Lower Moodna Creek. In the span of 15 months, Hurricane Irene, Tropical Storm Lee, and Hurricane Sandy each have caused significant flooding throughout the Moodna Creek watershed, damaging public facilities, roadways, and private properties. Both sub-basin communities have noted a concern about increased flood risk as more development occurs.

As global temperatures rise, climate models are predicting more intense rainfall events. And, the flood risk for communities along waterways — like the Moodna Creek watershed — will likely increase as time passes. In order to understand existing and future risk from flood events in this flood-prone area, a flood risk management strategy needed to be developed. The strategy uses a cost-benefit analysis to review the feasibility of each measure and the overall impact in reducing flood risks.

With funds provided from a 2016 grant program sponsored by the New England Interstate Waters Pollution Control Commission (NEIWPCC) and the New York State Department of Environmental Conservation’s (NYCDEC) Hudson River Estuary Program (HEP), Princeton Hydro along with a variety of project partners completed a flood assessment and flood mitigation analysis specific to the Lower Moodna Creek watershed.

Let’s take a closer look at our work with the Lower Moodna Creek watershed, and explore some of the methods used to estimate flood risk and develop a flood management strategy:

Lower Moodna Creek Watershed Flood Assessment & Analysis

The primary Lower Moodna Creek project goals were to assess flood vulnerabilities and propose flood mitigation solutions that consider both traditional engineering strategies and natural systems solution approaches (land preservation, wetland/forest restoration, green infrastructure and green water management). The project team focused on ways to use the natural environment to reduce risk.  Instead of strictly focusing on just Moonda Creek, the team took a holistic approach which included all areas that drain into the river too. These analyses were incorporated into a Flood Assessment Master Plan and Flood Mitigation Plan, which will serve as a road map to reducing flooding issues within the watershed.

Managing Flood Risk

The first step in managing flood risk is to understand what type of exposure the communities face. The Moodna Creek project modeled flooding within the watershed during normal rain events, extreme rain events, and future rain events with two primary goals in mind:

Visual assessment being conducted in flood-prone areas of Moodna Creek Watershed.

  • Assess the facilities, infrastructure, and urban development that are at risk from flooding along the Moodna Creek and its tributaries within the study area.
  • Develop a series of hydrologic and hydraulic models to assess the extent of potential flooding from the 10-year (10%), 100-year (1%),  and 500-year (0.2%) storm recurrence intervals within the study area. The modeling includes flows for these storm events under existing conditions and also hypothetical scenarios with predicted increases in precipitation and population growth.

 

The project team used these models and data to propose and evaluate a series of design measures that help reduce and mitigate existing and anticipated flood risk within the study area. Where possible, the proposed solutions prioritized approaches that protect and/or mirror natural flood protection mechanisms within the watershed such as floodplain re-connection and wetland establishment. In addition to flood protection, the project components also provide water quality protection, aesthetics and recreation, pollutant reduction, and wildlife habitat creation.

Land Use and Zoning

Zoning is a powerful tool that determines a region’s exposure to hazards and risk. Zoning determines which uses are permitted, or encouraged, to be built in moderate and high-risk areas. It also prevents certain uses, such as critical facilities, from being built in those areas. Zoning is also a determinant of a region’s character and identity.

In the Lower Moodna Creek watershed, a large majority (82%) of land is zoned for residential use. However, in the flood-prone areas, there is a higher ratio of areas zoned for non-residential uses (commercial, industrial) than in areas that are zoned for potential future development. Specifically, within the 10-year storm recurrence floodplain, 30% of the land is zoned for industrial use. This is likely because several facilities, such as wastewater treatment plants and mills, require access to the river and were strategically developed to be within immediate proximity of waterfront access. The Lower Moodna zoning analysis demonstrated a general preference within watershed to limit residential use of flood-prone areas. 

Land Preservation

Preserving land allows for natural stormwater management, as well as limits the exposure of development, and minimizes sources of erosion within the watershed. Preserved land also maintains the hydrologic and ecologic function of the land by allowing rainwater to be absorbed or retained where it falls and thus minimizing run-off. If the land within the floodplain is preserved, it will never be developed, and therefore the risk — a calculation of rate exposure and the value of the potential damage — is eliminated.  Therefore, land preservation, both within the floodplains and in upland areas, is the best way to minimize flood damage.

Conserved riparian areas also generate a range of ecosystem services, in addition to the hazard mitigation benefits they provide. Protected forests, grasslands, and wetlands 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.

Within the mapped Lower Moodna floodplains, our assessment determined that there appears to be a slight priority for preserving land most at-risk for flooding. This is likely a consequence of prioritizing land that is closest to riparian areas and preserving wetland areas, which are the most likely to experience flooding. Within the floodplains for the 10-year storm, approximately 22.7% is preserved. For the 100-year storm, approximately 21.2% of the land is preserved. Within the 500-year storm, this number drops slightly to 20.3%. These numbers are so close in part because the difference between the 10-year, 100-year, and 500-year floodplains are small in many areas of the watershed.

Hydrology and Hydraulics

Hydrology is the scientific study of the waters of the earth, with a particular focus on how rainfall and evaporation affect the flow of water in streams and storm drains. Hydraulics is the engineering analysis of the flow of water in channels, pipelines, and other hydraulic structures. Hydrology and hydraulics analyses are a key part of flood management.

As part of this flood assessment, Princeton Hydro created a series of hydrologic and hydraulic (H&H) models to assess the extent of potential flooding from the 10-year, 100-year, and 500-year storm recurrence intervals within the Lower Moodna. The modeling, which included flows for these storm events under existing conditions and future conditions based on predicted increases in precipitation and population growth, makes it easier to assess what new areas are most impacted in the future.

These are just a few of the assessments we conducted to analyze the ways in which flooding within the watershed may be affected by changes in land use, precipitation, and mitigation efforts. The flood models we developed informed our recommendations and proposed flood mitigation solutions for reducing and mitigating existing and anticipated flood risk.

Check out Part Two of this blog series in which we explore flood risk-reduction strategies that include both traditional engineering and natural systems solutions:

Part Two: Reducing Flood Risk in Moodna Creek Watershed

For more information about Princeton Hydro’s flood management services, go here: http://bit.ly/PHfloodplain.

 

New Green Infrastructure Toolkit for Municipalities

Our partner, New Jersey Future, just launched a brand new, interactive website toolkit to help municipalities across the state incorporate green infrastructure projects into their communities. The New Jersey Green Infrastructure Municipal Toolkit will provide expert information on planning, implementing, and sustaining green infrastructure to manage stormwaterThis toolkit acts as a one-stop resource for community leaders who want to sustainably manage stormwater, reduce localized flooding, and improve water quality.

According to the United States EPA, a significant amount of rivers, lakes, ponds, bays, and estuaries in New Jersey fall into the “Impaired Waters” category, meaning that one or more of their uses are not being met. This reality makes green infrastructure more important than ever in the effort to protect our waterways. When it rains, stormwater creates runoff, which often carries pollution to various types of waterbodies. Green stormwater infrastructure helps to absorb and filter rainwater, reducing the pollution entering our waterways and mitigating flooding in our communities. In urban areas, green infrastructure utilizes natural vegetation to divert stormwater, creating a cost-effective and aesthetically-pleasing way to manage water during rain events.

“We designed this toolkit to bring to light the benefits and importance of investing in green infrastructure at the local level,” said Dr. Stephen Souza, co-founder of Princeton Hydro. “Since the current NJ stormwater rules do not require green infrastructure, we hope to inspire municipal engineers and planning board members to believe in the value through our toolkit. Additionally, we hope it will serve as an educational resource to local officials and decision makers in the Garden State.”

For this project, Princeton Hydro was contracted by Clarke Caton Hintz, an architecture, design, and planning firm, leading this effort on behalf of the nonprofit organization New Jersey Future. Our expert engineers and scientists provided real-world examples integrating green infrastructure into development, in hopes of showing those using the toolkit real world evidence of how green infrastructure can be a part of the daily lexicon of stormwater management. Additionally, Dr. Stephen Souza developed performance standards that municipalities can integrate into stormwater management plans, which are available in the Green Infrastructure Municipal Toolkit.

Mitigation Milestone Reached at Mattawoman Creek Mitigation Site

Photo courtesy of GreenVest

Mattawoman Creek Mitigation Project will Restore and Protect 80+ Acres of Mattawoman Creek, Chesapeake Bay’s Most Productive Tributary

As one of the Chesapeake Bay’s most productive tributaries and a vital part of Maryland’s natural resources, Mattawoman Creek supports some of the largest populations of finfish, amphibians, and birds in the state. A collaborative team of private and public sector entities have designed the “Mattawoman Creek Mitigation Site” in Pomfret, Charles County, Maryland, an effort that will enhance or create 64+ acres of wetlands and restore nearly 3,800 linear feet of this perennial stream.  With over 28,500 native trees and shrubs to be planted, this mitigation project will result in 80+ acres of continuous, forested wetland with complex and diverse vegetative communities. It is expected to provide a wide array of habitat to resident and transient wildlife, including birds, reptiles, invertebrates, amphibians and rare, threatened and endangered species.

Unique to this project, Mattawoman Creek Mitigation Site is Maryland’s first-ever Umbrella Mitigation Banking Instrument (UMBI) for federal and other government agency use.   A UMBI is the bundling of multiple mitigation banks into one agreement in order to streamline the regulatory approval process, thereby eliminating steps and involving fewer resources. The Maryland UMBI document helps the USAF and other public agencies secure certainty of cost and schedule, facilitate timely permit issuance, and expedite the satisfaction of their permitted requirements for planned capital improvement projects. This approach also maximizes the scale of restoration and resulting land protection and efforts, creating contiguous blocks of habitat with greatly enhanced benefits compared to single, permittee-responsible projects. This precedent was a result of a partnership between United States Air Force (USAF) and Joint Base Andrews (JBA), U.S. Army Corps of Engineers (USACE), Maryland Department of the Environment (MDE), GreenTrust Alliance, GreenVest, and Princeton Hydro.

Projects completed under the UMBI will reduce federal and state workload expediting the regulatory review and issuance of permits by the MDE and USACE. Additionally, projects completed under this UMBI will aid in compliance with the Federal Paperwork Reduction Act where federal regulatory staff can evaluate success and performance issues for multiple permittees at one single habitat restoration or mitigation site. In addition, federal costs are capped, and liabilities  are transferred through to GreenVest, the private sector operator, and GreenTrust Alliance, the nonprofit bank sponsor, who will also serve as the long-term steward of sites restored under this program.

Pictured is the southern restoration area after
sorghum germination, prior to wetland creation
and reestablishment.
A function-based stream assessment was
performed on the degraded channel.

 

Photo courtesy of GreenVestDesign, engineering/modeling, and permitting of the site was completed by  Princeton Hydro and GreenVest under our currently Ecosystem Restoration contract with the USACE. Princeton Hydro also provided an Environmental Assessment and Environmental Baseline Survey, and conducted a geotechnical investigation, which included the advancement of test pits, visual and manual investigation techniques and logging, infiltration testing, laboratory soils testing, and seasonal high-water table estimations.

A wetland water budget was also developed for the proposed wetland creation and restoration to determine if sufficient water is available to establish or reestablish wetlands on the site. It was also used to inform design development including proposed grading and plant community composition. The establishment and re-establishment of wetlands on the site will be accomplished through directed grading, ditch plugging and stream restoration designed to maximize the retention of surface water, floodplain re-connection, and groundwater inputs.

Highlights from the Mattawoman Creek Wetland and Stream Mitigation project:
  • 80 acres of land were placed into conservation easement and removed from active row crop production and cattle pasture. The easement, which is held by GreenTrust Alliance, provides permanent protection for all 80 acres.
  • Over 64 acres of wetlands will be restored, created, enhanced or preserved, which will sequester approximately 75 tons of carbon per year.
  • 3,798 linear feet of perennial stream will be restored by re-establishing, historic floodplain access during more frequent storm events, stabilizing hydraulics and geomorphology, and adding aquatic habitat value.
  • Full integration of the wetland and stream restoration elements will occur exponentially, increasing anticipated functions and values in the post construction condition. Functions include: storm damage and flood attenuation, groundwater recharge and discharge, nutrient cycling and sequestration, local water quality improvement, and wildlife habitat enhancements.
  • This project will also create and enhance the forested wetland and stream habitat for the State-listed Threatened Selys’ Sundragon (Helocordulia selysii).
  • As part of the site design, over 28,500 native trees and shrubs will be planted.
  • The Mattawoman Creek Mitigation Site is located within a Tier 3 Biodiversity Conservation Network area. These areas are classified by the Department of Natural Resources as “highly significant for biodiversity conservation” and are priority conservation areas that support critical species and habitats.
  • The project will yield advanced mitigation values: 7.913 in wetland credits and 1,595 in stream credits. These credits are durable and will be available for JBA’s use in order to satisfy permitted impacts associated with planned capital improvement projects.

Over 6,000 acres (25%) of the Mattawoman Creek watershed has been protected by public ownership and various conservation and agricultural easements, which, in addition to the Mattawoman Creek Mitigation Site, help ensure that Mattawoman Creek forever remains a high-quality destination for outdoor recreation.

Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of tidal and freshwater wetland rehabilitation projects. To learn more about our wetland restoration, creation, and enhancement services, visit: http://bit.ly/PHwetland

October Events Spotlight: Conferences, Workshops & Galas

Throughout October, Princeton Hydro is proud to participate in a number of conferences and events on topics ranging from floodplain management to ecological restoration to dam removal:

October 10: Society for American Military Engineers (SAME) MEGA Maryland Small Business Conference

The conference, being held in Baltimore, gives small and minority businesses in the architecture, engineering and construction industries the opportunity to come together with federal agencies in order to showcase best practices and highlight future opportunities to work in the federal market. The program consists of networking events, a variety of speakers and small business exhibits. Be sure to stop by the Princeton Hydro booth to say hello to President Geoffrey Goll, P.E. and Communications Strategist Dana Patterson.

LEARN MORE & REGISTER

 

October 11: Great Swamp Gala & Silent Auction

The Great Swamp Watershed Association, a nonprofit organization dedicated to protecting and improving the water resources of the Passaic River region, is hosting its 2018 Gala & Silent Auction. This year’s event is being, held in honor of former New Jersey Governor Thomas Kean, for his environmental leadership during his administration for enacting landmark protections for New Jersey’s shoreline and freshwater wetlands. present and future generations. The evening will include a cocktail hour, dinner banquet, expansive silent auction, and remarks delivered by Governor Kean. Princeton Hydro is proud to be a Benefactor of the event and looking forward to attending.

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October 11 – 13: Atlantic Estuarine Research Society (AERS) Fall Meeting

The theme of this year’s AERS Fall Meeting is “The power of framing your message: It’s not what you say, it’s how you say it!” Participants will gather at Stockton University to hear a variety of ignite-style presentations about misconceptions that typically surround scientific work, how to address them, and how to re-frame your message to be better understood by the general public and other non-scientists and increase stakeholder involvement. Princeton Hydro’s Senior Aquatics Scientist Jack Szczepanski, PhD will be attending the conference; chat with him to learn more about our pond and lake services.

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October 11 – 13: Society for Ecological Restoration (SER) New England 2018 Regional Conference

This year’s SER New England conference brings together stewards, researchers, students, regulators, community activists and practitioners to explore innovative ecological restoration techniques and projects that connect communities within and across ecosystems. The conference includes a variety of plenary talks, field trips, workshops and a keynote address, which will be given by Stewart Diemont of SUNY College of Environmental Science and Forestry. The keynote, titled “Learning from the People and the Land: Traditional Ecological Knowledge Toward Restoration of Ecosystems and of our Connection with Nature,” is free and open to the public.

Members of the Princeton Hydro are attending the conference and leading two sessions: Laura Wildman, Water Resources and Fisheries Engineer, is leading a workshop about implementing dam removal to restore rivers. Paul Woodworth, Fluvial Geomorphologist, is presenting on the post-dam removal monitoring of active and passive restoration approaches utilizing the Hyde Pond Dam removal as a tangible example.

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October 11: Hudson-Delaware Chapter of the Society of Environmental Toxicology and Chemistry (HDC-SETAC) 2018 Fall Workshop

HDC-SETAC is a professional society for scientists, engineers and related disciplines concerned with environmental science and health throughout the Hudson River and Delaware River metropolitan area. The 2018 Fall Workshop, being held at Villanova University, aims to enhance participants’ knowledge of “Harmful Algal Blooms and other Emerging Contaminants.” Princeton Hydro’s Director of Aquatic Programs Dr. Fred Lubnow is giving a presentation on “The Monitoring and Management of Cyanotoxins in Raw Water Supplies.” We hope to see you there! 

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October 12: Association of New Jersey Environmental Commissions (ANJEC) 2018 Environmental Congress

ANJEC, a nonprofit organization supporting efforts to protect the environment and preserve natural resources in communities throughout New Jersey, is hosting its 45th Annual Environmental Congress at Mercer County College. The Environmental Congress is an annual statewide gathering of environmental commissions, local officials, agencies, citizen groups and environmental organizations, which includes an exhibitors hall, farmer’s market, and workshops on a variety of current environmental topics. Princeton Hydro, a business member of the ANJEC, will be exhibiting during the event. Stop by the booth to say hello to Dr. Stephen J. Souza, Princeton Hydro Founder and ANJEC Board of Trustees member, and Dana Patterson, Communications Strategist for Princeton Hydro.

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October 23 – 25: New Jersey Association for Floodplain Management (NJAFM) 14th Annual Conference

NJAFM is hosting its 14th Annual Conference and Exhibition in Atlantic City, NJ. Participants will attend meetings and seminars covering topics, including hazard mitigation, flood insurance, infrastructure, mapping, planning, flood modeling, regulations, floodproofing, stormwater management, flood proofing, construction standards and more. Princeton Hydro’s Christiana Pollack, GISP, CFM and NJDEP’s Jessica Jahre, PP, AICP, CFM are giving a presentation, titled “A Flood Assessment for the Future,” for which they’ll showcase a flood assessment and flood mitigation analysis that Princeton Hydro performed in the Lower Moodna Creek Watershed.

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October 23: “Undamming the Hudson River” Film Screening and Panel Event, Free & Open the Public

Riverkeeper and Patagonia present the premiere of “Undamming the Hudson River,” a short documentary film by National Geographic filmmaker Jon Bowermaster showcasing Riverkeeper’s efforts to restore natural habitat by eliminating obsolete dams throughout the Hudson River Estuary. The screening will be followed by refreshments and a panel discussion, moderated by Bowermaster, featuring experts in the field and an audience Q&A. Panelists, include:

  • Laura Wildman, PE – Water Resources and Fisheries Engineer, Princeton Hydro
  • George Jackman – Habitat Restoration Manager, Riverkeeper
  • Gwen McDonald – Director of Green Projects, Save the Sound
  • Andy J. Danylchuk, PhD – Associate Professor of Fish Conservation, UMASS Amherst, and Patagonia Fly Fishing Ambassador

This event is free and open to the public and will take place at Patagonia SoHo, 72 Greene St, New York, NY 10012 from 7:30 – 10pm.

RSVP HERE

 

October 24: Mid-Atlantic Chapter of the Urban & Regional Information Systems Association (MAC URISA) 2018 Conference

MAC URISA 2018, the largest GIS conference in the Mid-Atlantic region, will showcase outstanding and innovative uses of GIS technologies in the area. The program includes a variety of presentations, breakout sessions, a GIS Techspo forum, lightening talks, and more. Thomas Hopper, Princeton Hydro’s GIS Analyst, is providing a technical demonstration on the Linkage Mapper GIS Toolkit, which was created by the Nature Conservancy to support habitat connectivity analyses.

LEARN MORE & REGISTER HERE

 

October 30 – November 2: North American Lake Management Society (NALMS) Conference

NALMS is hosting its 38th International Symposium in Cincinnati Ohio, titled “Now Trending: Innovations in Lake Management.” This year’s symposium includes a robust exhibit hall, a variety of field trips, and a wide array of presentations on topics ranging from the latest in monitoring technologies to combating invasive species to nutrient and water quality management and more. Princeton Hydro’s Dr. Fred Lubnow, Director of Aquatic Programs, and Dr. Stephen Souza, Founder, both of whom have been members of NALMS since its inception, are presenting and exhibiting during the conference.

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October 31 – November 2: Society for American Military Engineers (SAME) Small Business Conference (SBC)

SAME gives leaders from the A/E/C, environmental, and facility management industries the opportunity to come together with federal agencies in order to showcase best practices and highlight future opportunities for small businesses to work in the federal market. Princeton Hydro is proud to be attending the 2018 SAME SBC Conference, which is being held in New Orleans and co-locating with the Department of Veteran’s Affairs’ National Veterans Small Business Engagement. The program consists of networking events, small business exhibits, a variety of speakers and much more.

LEARN MORE & REGISTER

 

STAY TUNED FOR OUR NOVEMBER EVENT SPOTLIGHT!

Dam Removal Underway in Watertown, Connecticut

Deconstruction of the Heminway Pond Dam, Watertown, CT on July 16, 2018.

As dams age and decay, they can become public safety hazards, presenting a failure risk and flooding danger. According to American Rivers, “more than 90,000 dams in the country are no longer serving the purpose that they were built to provide decades or centuries ago.” Dam removal has increasingly become the best option for property owners who can no longer afford the rising cost of maintenance and repair work required to maintain these complex structures.

Dams can also cause environmental issues such as blocking the movement of fish and other aquatic species, inundating river habitat, impairing water quality, and altering the flow necessary to sustain river life. Removing nonfunctional, outdated dams can bring a river back to its natural state and significantly increase biodiversity for the surrounding watershed.

A view from the site of the Heminway Pond Dam removal on July 19, 2018.

Currently, work is underway in Watertown, Connecticut to remove the Heminway Pond Dam, which restricts fish passage in Steele Brook, creates a pond with increased water temperatures and high bacterial levels due to high geese populations, and encourages deposition of iron precipitate in the stream channel just downstream of the dam.

Princeton Hydro designed the engineering plans, managed permitting and is now overseeing construction for the removal project. The removal of the Heminway Pond Dam is identified as an integral component in addressing water quality impairment between the dam and Echo Lake Road.

CT DEEP recently published this piece encapsulating the Heminway Pond Dam removal project:

REMOVAL OF HEMINWAY POND DAM ON STEELE BROOK IN WATERTOWN UNDERWAY

Upstream at rock-filled breach in Heminway Pond Dam and shallow, dewatered impoundment on Steele Brook in Watertown (7-18-18)

After almost 15 years of discussion and planning with the Town of Watertown and other partners, removal of Heminway Pond Dam on Steele Brook in Watertown finally got underway in early July.  Though no longer functional, the dam and pond were originally constructed to supply water for a former thread/string mill.  The Town acquired the dam and pond from the Siemon Company, the most recent owner, in 2007 with an eye towards removing the dam, restoring the river and converting the dewatered impoundment area into a passive recreation area, including an extension of the Steele Brook Greenway.  With these goals in mind, the Town approached CT DEEP for help with removal of the dam.

As it turns out, CT DEEP, has also had a strong interest in seeing this dam removed.  It is anticipated that dam removal will improve the hydrology in this section of Steele Brook and eliminate a water quality impairment which manifests itself during hot weather and low flow conditions, as an orange-colored plume of water (due to iron precipitate) immediately downstream of the dam that impacts aquatic life.  Dam removal would also benefit fisheries by restoring stream connectivity and habitat.

Working towards these mutual goals, CT DEEP was able to provide federal CWA 319 nonpoint source grant funding to USDA NRCS to develop a watershed-based plan for Steele Brook to address nonpoint source impairments that includes a dam removal feasibility analysis for Heminway Pond Dam.  Based on the recommendations in this plan, CT DEEP subsequently provided additional 319 grant funds to the Town of Watertown to hire a consultant to develop a dam removal design package, and assist with permitting and preparation.

With the Town of Watertown as a strong and vested partner, CT DEEP is now helping this project over the finish line by providing a combination of 319 and SEP funds to accomplish the actual dam removal and restoration of Steele Brook.  Dayton Construction Company is performing the construction and Princeton Hydro is the consultant overseeing the project on behalf of the Town.  The Northwest Conservation District is also assisting with the project.  It is anticipated that the majority of the work will be completed by this Fall.  U.S. EPA, ACOE and CT DEEP have all played active roles with regard to permitting the project.

 

A view of the first notch during the Heminway Pond Dam removal on July 17, 2018.

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of dozens of small and large dams in the Northeast. Click here to read about a recent dam removal project the firm completed on the Moosup River. And, to learn more about our dam and barrier engineering services, visit: bit.ly/DamBarrier.