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

Conservation Spotlight: Reducing Flood Risk and Restoring Wetlands in Jamaica Bay

Located in Queens, New York on the northern shore of Jamaica Bay, Spring Creek South contains approximately 237 acres of undeveloped land, including wetlands and 2.4 miles of coastline. The site is bounded by the Howard Beach residential neighborhood in Queens, a commercial area along Cross Bay Boulevard, the Belt Parkway, and Jamaica Bay. The northwest section of Spring Creek South is part of the National Park Service’s Gateway National Recreation Area, and is largely comprised of small patches of degraded tidal marsh and disturbed and degraded upland ecosystems.

On October 29, 2012, Hurricane Sandy drove a catastrophic storm surge into the New Jersey and New York coastlines. Spring Creek South and the surrounding community of Howard Beach experienced record flooding and damage to property and critical infrastructure. Storm tides caused damage and erosion along the shoreline and in the salt marsh area, degrading important habitat and leaving the site vulnerable to invasive species.

Hurricane Sandy Aftermath at Howard Beach, taken 10/30/2012 by Pam Andrade

The New York State Division of Homeland Security and Emergency Services (NYSDHSES) was awarded funding from FEMA’s Hazard Mitigation Grant Program to restore Spring Creek South. The U.S. Army Corps of Engineers (USACE) New York District, serving as project administrator, contracted Princeton Hydro to provide ecosystem restoration services. The goal of the project is to reduce future flood risk exposure while also protecting, restoring, and improving the quality and function of ecological systems; improving stormwater management and water quality; and enhancing the park’s visitor experience.

To achieve this goal, the project team is using an integrated approach that involves utilizing green infrastructure to create a natural barrier for the community and reduce the risks of coastal storms. Project activities include berm construction and the restoration of tidal marsh, creation of freshwater wetland forest, and creation of maritime shrub, forest, and grassland habitats, as well as stabilization of the existing shoreline.

On December 31, 2018, we completed Phase One of the project, which entails engineering design and preliminary permitting. More specifically, we’ve provided conceptual planning; analysis of subsurface soils for geotechnical properties and hazardous waste; coastal and freshwater wetland delineations; biological benchmarking analysis; and the development of sea level rise curves and two-dimensional hydrologic and hydraulic coastal modeling. As part of the hydrology study, we analyzed what the site could be expected to look like in 50 years due to climate changes and sea level rise. Our engineering design was also brought to 65% completion.

We also obtained permits, prepared the Environmental Assessment (EA), and oversaw the National Environmental Policy Act (NEPA) process. The EA received a “Finding of No Significant Impact” (FONSI) from FEMA, which means the environmental analysis and interagency review concluded that the project has no significant impacts on the quality of the environment.

Due to the complex nature of this project and its location, we are coordinating with a variety of different entities, including the local Howard Beach Community Board, the FAA (proximity to JFK International Airport), Port Authority, USACE, NOAA Fisheries, USFWS, USEPA, NYSDEC, NYC DEP, the National Park Service, HDR Engineering and WSP Engineering.

Phase Two of the project is the construction phase, which is expected to take about two years to complete. A key part of the Spring Creek South construction activities is the restoration of approximately 40 acres of tidal marsh, which is anticipated to improve water quality locally by stabilizing sediment, reducing erosion, and filtering dissolved particulate materials. The project team will restore existing coastline areas and install a salt marsh along the shoreline. Planted with native flora, like Spartina alterniflora, a perennial deciduous grass found in intertidal wetlands, the coastal salt marsh will help to stabilize sediment. Additionally, removing invasive species like Phragmites australis from the area and replacing it with native plant species will increase the ability for native vegetation to colonize the site, improve vegetative diversity, and reduce fire risk in the park.

A forested wetland area and berm will also be created in order to provide the surrounding communities with natural shields and buffers to future storms. The berm, with an elevation of 19 feet (NAVD88), will help to manage the risk of storm surge flooding caused by coastal storms. The forested wetland area will also provide improved stormwater runoff storage, naturally filter stormwater, and, via flap gates, direct its flow toward Jamaica Bay, away from residential and commercial properties.

These measures will help to dissipate wind and wave energy, increase shoreline resilience, improve stormwater management at the site, and create habitat that increases the ecological value and biodiversity at the site, while providing resilience benefits. Restoration activities will benefit vulnerable and rare ecological communities by producing localized environmental enhancements, including improving water quality and creating and restoring habitat. The project also increases opportunities for recreational uses such as wildlife viewing/photography, fishing, and nature study.

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

 

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.

 

November Events Spotlight: Conferences Throughout the Country

Princeton Hydro is participating in a variety of conferences taking place throughout the country that address topics ranging from lake management to green infrastructure resiliency:

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.

LEARN MORE

 

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.

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November 2: The 2nd Annual New Jersey Watershed Conference

We are a proud sponsor of this year’s New Jersey Watershed Conference, which is an educational event that aims to advance knowledge and communications on issues related to water quality and quantity across the state. The agenda features a variety of presentations from local experts on watershed management, stormwater, green infrastructure, and the problems and solutions related to the health of our watersheds. Princeton Hydro is exhibiting & our Marketing Coordinator, Kelsey Mattison, is leading a workshop on “How Social Media can be a Champion for your Watershed.”

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November 4 – 8: 2018 American Water Resources Association Conference

The AWRA’s 53rd Annual Water Resources Conference is being held in Baltimore, MD. Community, conversations and connections are highlights of every AWRA conference and the 2018 conference will provide plenty of opportunities for all three, including an exhibitor hall, networking events, and variety of presentations and technical sessions. Princeton Hydro’s Christiana Pollack, GISP, CFM is giving a presentation on flood assessment and mitigation. 

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November 8 – 10: Engineers Without Borders (EWB) USA Conference

The EWB, a nonprofit humanitarian organization that partners with developing communities worldwide in order to improve their quality of life, is hosting its USA National Conference in San Francisco.  The ​annual ​conference ​will ​address ​the ​theme ​“Engineers Unlock Potential.” ​Experts, ​practitioners, ​decision-makers, ​young ​professionals ​and ​students ​from ​a ​range ​of ​sectors ​will come together to network, exchange ideas, foster new thinking and develop solutions to the world’s most pressing infrastructure ​challenges. Princeton Hydro Staff Engineer Natalie Rodrigues, EIT, CPESC-IT, a EWB member, is attending the conference and presentation. Her session, titled “So You Think You Might Like to be an EWB Regional Officer or State Representative, ” is designed for those interested in taking the next step beyond Chapter or Project participation at EWB-USA, as well as for current Regional Steering Committee members who want to “amp up” their game.

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November 13: Society for American Military Engineers (SAME) Philadelphia Resiliency Symposium

SAME Philadelphia is hosting an all day symposium featuring experts on infrastructure resiliency in the face of extreme storms, flooding and other natural disasters. Presentation topics include, Flood Hazard Risk and Climate Change Effects for Bulk Oil Storage Facilities; Post-Storm Infrastructure Improvements and Stream Restoration; and Resilience Risk Analysis and Engineering. Princeton Hydro President Geoffrey Goll, P.E. is giving a presentation titled, “Enhancing Coastal Habitat & Increasing Resiliency through Beneficial Reuse of Dredged Material in New Jersey.” We hope to see you there!

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November 16: NJ Chapter American Water Resources Association (NJ-AWRA) Future Risk Symposium

As the frequency and intensity of storm events changes, how should watershed managers, engineers, and planners make informed decisions for the future? NJ-AWRA’s 2018 Future Risk Symposium, held at Duke Farms in Hillsborough, NJ, will focus on Future Flooding in Riverine Systems with presentations on climate trends, modeling, and planning that can be used in NJ to prepare for future flood events in New Jersey’s riverine systems. Princeton Hydro’s Christiana Pollack, GISP, CFM is giving a presentation on flood assessment, and the concepts and methods used to estimate flood risk for existing conditions and the year 2050.

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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

Employee Spotlight: Meet Our New Team Members

We’re excited to welcome two new staff members and seven new part-time staff & interns to our team who are spread throughout our Ringoes, Sicklerville, and Glastonbury offices.

 

Full-Time Staff Members:
Kelsey Mattison, Marketing Coordinator

Kelsey is a recent graduate of St. Lawrence University with a degree in English and environmental studies and a passion for environmental communication. Through her extracurricular work with various nonprofit organizations, she has developed expertise in social media management, content writing, storytelling, and interdisciplinary thinking. Kelsey believes that effective communication needs to be multi-faceted, which is reflected in the diversity of her experience. She served as Photography Editor of St. Lawrence University’s newspaper, worked in digital media for the environmental outreach program of St. Lawrence University,  produced stories for Northern New York’s public radio station, and developed feature content for St. Lawrence County’s Chamber of Commerce. As a member of the Princeton Hydro team, she aims to further its mission by taking creative approaches to communicating about our shared home: Planet Earth. In her free time, Kelsey enjoys dancing of all sorts, going on long walks with her camera, and spending time with friends and family in nature.

Christine Worthington, Accounting Assistant

Christine is a detailed-oriented Accounting Assistant who has over 15 years of experience working in office administration for local businesses. She loves vacationing in Jamaica with her husband and spending time with her two sons & three grandchildren. In her free time, she listens to country music and visits new cities like Nashville.

 

Part-time Staff, Field Assistants & Interns:
Heidi Golden, PhD, Aquatic Ecologist

Heidi is an aquatic ecologist and evolutionary biologist with a strong background in fish monitoring, aquatic habitat assessment, population and community ecology, and population genetics and genomics. She holds a PhD in Ecology and Evolutionary Biology and a Master of Science in Forestry and Wildlife Biology. In addition to her ecology expertise, Heidi has experience in GIS analysis, R statistical programing, scientific writing, permitting, and a wide range of field and laboratory techniques. Prior to joining Princeton Hydro, Heidi worked as a postdoctoral researcher with The Woods Hole Research Center, The Marine Biological Laboratory, and The University of Connecticut, where she continues to serve as adjunct faculty to the Department of Ecology and Evolutionary Biology. She investigated ecological and evolutionary responses of fish populations to rapid environmental change. Her professional experience also includes coordinating field expeditions in remote locations of the Alaskan Arctic, tagging and tracking thousands of fish through remote PIT-tag antenna arrays, using environmental DNA to monitor fish presence and movement, and developing experiments to assess ecosystem responses to change. She enjoys raising ducks, swimming in cold rivers, hiking, kayaking, camping, and family.

Andrew Greenlaw, Water Resources Intern

Andrew Greenlaw is in his fourth year at the University of Connecticut, majoring in Civil Engineering with a minor in Environmental Engineering. Before studying engineering he taught at a Marine science summer camp in Groton, CT, off of the Long Island Sound. He joined Princeton Hydro with the hope of combining his biological sciences experience with his academic engineering knowledge. He enjoys hiking, fishing, and just about any outdoor sport.

Ryan Lindsay, Water Resources Intern

Ryan is a double major at Rowan University focusing in both Civil & Environmental Engineering and Computer Science, and is currently finishing his final semester. He’s worked on various engineering clinic projects ranging from developing a pavement analysis program for Rhode Island DOT to a feasibility study to assist those with disabilities. His current project is to develop a home security/monitoring system with an accompanying mobile application. In the future, Ryan hopes to develop civil engineering applications for use by design engineers, and hopes that with his unique skillset he can make future engineers’ jobs easier and more efficient. Ryan enjoys playing baseball, listening to music, hiking and hanging out with friends and family.

Nick Niezgoda, Aquatics Field Assistant

Nick graduated in 2017 from Western State Colorado University with a B.S. in Biology. He lived and worked at Rocky Mountain Biological Laboratory studying defense genotypes of B.stricta under Duke University’s Tom Mitchell-Olds Lab in 2016 and 2018. At RMBL, He also assisted in trapping and banding of Mountain White-Crowned Sparrows. He enjoys cycling, hiking, and birding!

Emily McGuckin, Aquatics Field Assistant

Emily is a recent graduate from Stockton University, with a BS in marine biology, and a minor in environmental science. She just finished up an internship with the American Littoral Society at Sandy Hook, where she helped manage the fish tagging program and educating others on the importance of maintaining an accurate fisheries database. She has experience in both freshwater and marine ecosystem management and is excited to continue learning about ecological restoration and management.  She is very interested in ecosystem resilience, specifically climate change and how it affects estuaries and estuarine organisms. Emily is hoping to attend graduate school in the near future to further her studies in marine science.

Pat Rose, Aquatics Field Assistant

Pat got interested in aquatics 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, TN as part of a Water Quality Team. While in Tennessee, he 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. The year, through AmeriCorps, he also worked with government organizations performing biological sampling and erosion monitoring in local streams. Pat is set to graduate from SUNY Oneonta with a M.S. in Lake Management in December. 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.

 

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.