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Princeton Hydro was formed in 1998 with the specific mission of providing integrated ecological and engineering consulting services. Offering expertise in aquatic and terrestrial ecology, water resources engineering, and geotechnical investigations, our staff provides a full suite of environmental services. Our team has the skill sets necessary to conduct highly comprehensive assessments; develop and design appropriate, sustainable solutions; and successfully bring those solutions to fruition. As such, our ecological investigations are backed by detailed engineering analyses, and our engineering solutions fully account for the ecological and environmental attributes and features of the project site. We take great pride in our reputation with both clients and regulators for producing high-quality projects over a wide variety of service areas; doing so requires a highly skilled team committed to keeping abreast with current research, technology and regulations. Our capabilities are reflected in our award-winning projects that consistently produce real-world, cost-effective solutions for even the most complex environmental problems.

SAME NJ Post Honors Princeton Hydro’s Marketing Manager

Princeton Hydro’s Marketing and Communications Manager Dana Patterson was presented with the Society of American Military Engineers (SAME) New Jersey Post’s “Young Member Award” for her efforts in maintaining and advancing the objectives of the organization.

Marketing and Communications Manager Dana Patterson was presented with the Society of American Military Engineers (SAME) New Jersey Post's "Young Member Award" for her efforts in maintaining and advancing the objectives of the organization.The mission of SAME is to build leaders and lead collaboration among government and industry to develop multidisciplinary solutions to national security infrastructure challenges. Princeton Hydro joined SAME as a sustaining member in 2018, and actively supports the organization and its goals. Ms. Patterson has been active with the New Jersey Post since joining Princeton Hydro in October of 2018, and was elected into the SAME New Jersey Post Board of Directors Secretary position in Summer of 2019. In addition to her board role, she is an active member of the SAME NJ Post Small Business Council and assists with the organization’s social media marketing.

“I am honored and humbled to accept this award from the SAME New Jersey Post. It has been rewarding to collaborate with such a dedicated group of volunteers who share insights and ideas on business development, leadership, and federal opportunity tracking, while also empowering youth to participate in the STEM field,” said Ms. Patterson. “I look forward to inspiring more members of the NJ community to engage with our organization.”

The SAME NJ Post 2020 Award Ceremony is held each year to recognize members for their outstanding contributions to the Post and its community. The following volunteers were also recognized with awards:

Congratulations to all the award winners and many thanks to SAME NJ Post.

For more information about SAME NJ Post, go here. To learn more about the national SAME organization, go here.

2019 Successes: A Year in Review

Over the last two decades, we’ve restored many miles of rivers, improved water quality in hundreds of ponds and lakes, and enhanced thousands of acres of ecosystems in the Mid-Atlantic and New England regions. In 2019, we had our best year yet. As we reflect back on 2019 and set our sights on 2020, we have many successes to celebrate:

1. We Designed the Largest Dam Removal in New Jersey.

The century-old Columbia Dam was removed and fish passage was restored on the 42-mile long Paulins Kill river, an important tributary to the Delaware River in northwestern New Jersey. On Earth Day 2019, just two months after the river finally flowed free, we were thrilled to discover the return of American shad upstream for the first time in over 100 years.

Hudson River Bear Mountain Bridge (Photo from Wikipedia)

2. We Conceptualized Six Sites Along the Hudson River for Habitat Restoration.

Our team completed a feasibility study for the U.S. Army Corps of Engineers (USACE), which identified and conceptualized restoration opportunities at six key sites. For this Hudson River Habitat Restoration Integrated Feasibility Study and Environmental Assessment, Princeton Hydro collected and analyzed data, reviewed existing conditions, and drafted conceptual restoration designs. Our final report was just highlighted by USACE at the 2019 Planning Community of Practice (PCoP) national conference at the Kansas City District as an example of a successfully implemented Ecosystem Restoration Planning Center of Expertise (ECO-PCX) project.

3. National and Regional News Outlets Featured Princeton Hydro Harmful Algal Bloom Experts.

After a record-breaking number of HABs broke out in lakes across the region, our Aquatics Team was called upon for their expertise and insights into why the outbreak was happening, what could be done to treat it, and what preventative actions will lessen the likelihood of future outbreaks. In addition to being featured in various regional news outlets covering the HABs topic, Princeton Hydro experts were featured in the New York Times and the Washington Post for their leadership at the largest lake in New Jersey, Lake Hopatcong. (Photo credit: Washington Post)

4. Our Staff Presented, Exhibited, and Attended Over 50 Events.

From galas to environmental conferences and river restoration tours to college courses, the Princeton Hydro team participated in more than 50 events throughout 2019. Dr. Clay Emerson, PE taught a Green Infrastructure Stormwater Management Course at Montclair University. Kelsey Mattison, Marketing Coordinator, presented at the 3rd Annual New Jersey Watershed Conference. And, at the New Jersey Land Conservation Rally, we had three presentations on citizen science, marketing strategy, and lake stewardship. Various team members rolled up their sleeves to volunteer to plant trees at Exton Park on Arbor Day, build a rain garden in Clawson Park, and restore eroding shoreline in Point Pleasant. Stayed tuned for more in 2020!

5. We’re Restoring the Northernmost Freshwater Tidal Marsh on the Delaware River.

Mercer County’s John A. Roebling Memorial Park is home to the northernmost freshwater tidal marsh on the Delaware River, Abbott Marshland, an area containing valuable habitat for many rare species. Unfortunately, the area has experienced a significant amount of loss and degradation, partially due to the introduction of the invasive Phragmites australis. The Princeton Hydro team proudly removed this invasive species and is restoring the marsh to enhance plant diversity, wildlife habitat, and water quality.

6. We Upcycled Christmas Trees to Stabilize an Eroding Shoreline for the First Time in NJ.

To prevent further erosion at the Slade Dale Sanctuary in Point Pleasant, dozens of volunteers helped stabilize the shoreline using recycled Christmas trees, a technique never been done before in New Jersey. The 13-acre Slade Dale Sanctuary is an important part of the local ecosystem and much work is being done there to restore the marsh and enhance the ecological function and integrity of the preserve. Princeton Hydro developed a conceptual and engineering design using living shoreline features, including tree vane structures to attenuate wave action, foster sediment accretion, and reduce erosion.

7. Princeton Hydro Earned Three Prestigious Awards.

The Friends of the Presumpscot River awarded Laura Wildman, P.E., with its “Chief Polin Award” for her accomplishments and efforts in bringing life back to the Presumpscot River and rivers across the nation. The New Jersey Highlands Coalition honored Founding Principal Dr. Stephen Souza with a Lifetime Achievement Award, touting his dedication to preserving and protecting New Jersey’s watersheds and natural resources. And, our Pin Oak Forest and Wetland Restoration project earned the “Land Ethics Award of Merit” from Bowman’s Hill Wildflower Preserve for its remarkable restoration achievements.

8. We’re Converting an Urban, Flood-Prone Industrial Site into a Thriving Public Park.

Along the Third River and Spring Brook, two freshwater tributaries of the Passaic River, a former industrial site that is highly-disturbed and flood-prone is being transformed into a thriving public park. The team broke ground on this important ecological restoration and urban wetland creation project in March and the restoration work continues. Princeton Hydro is serving as the ecological engineer to Bloomfield Township providing a variety of services and expertise.

9. Princeton Hydro Welcomed 12 New Staff and Added Two Key Positions.

As part of the expansion of our growing business, Princeton Hydro added 12 team members with expertise and qualifications in a variety of fields. In July, we announced a new executive position in the firm, Chief Operating Officer, to which Kevin M. Yezdimer, P.E. was appointed. We also created an internal Human Resources Department and hired Samara McAuliffe as Employee Relations Manager. Princeton Hydro has grown from a small, four-person idea operating out of a living room to a 65+ person qualified Small Business with six office locations in the Northeast region.

10. New Year, New Locations!

We’re moving on up! In 2019, we moved our D.C. Regional Office down the road from Annapolis, MD to Bowie, MD expanding into a larger office space to accommodate our staff growth and providing opportunity for more growth in the region. And, in late 2019, through our strategic partnership with Merestone Consulting, we opened a sixth office in Wilmington, Delaware. Stay tuned for more information!

 

Thank you for supporting Princeton Hydro and sharing our stories. We truly appreciate each and every one of our clients and partners. Cheers to a fruitful 2020 and beyond!

Feasibility Study Identifies Key Opportunities for Hudson River Habitat Restoration

Hudson River Bear Mountain Bridge (Photo from Wikipedia)

The Hudson River originates at the Lake Tear of the Clouds in the Adirondack Mountains at an elevation of 4,322 feet above sea level. The river then flows southward 315 miles to New York City and empties into the New York Harbor leading to the Atlantic Ocean. The Hudson River Valley lies almost entirely within the state of New York, except for its last 22 miles, where it serves as the boundary between New York and New Jersey.

Hudson River Basin (Image by USACE)Approximately 153 miles of the Hudson River, between the Troy Dam to the Atlantic Ocean, is an estuary. An estuary is defined by the USEPA as “a partially enclosed, coastal water body where freshwater from rivers and streams mixes with salt water from the ocean. Estuaries, and their surrounding lands, are places of transition from land to sea. Although influenced by the tides, they are protected from the full force of ocean waves, winds and storms by landforms such as barrier islands or peninsulas.”

The Hudson River’s estuary encompasses regionally significant habitat for anadromous fish and globally rare tidal freshwater wetland communities and plants, and also supports significant wildlife concentrations. As a whole, the Hudson River provides a unique ecosystem with highly diverse habitats for approximately 85% of New York State’s fish and wildlife species, including over 200 fish species that rely on the Hudson River for spawning, nursery, and forage habitat.

The Hudson is an integral part of New York’s identity and plays a vital role in the lives of the people throughout the area. Long valued as a transportation corridor for the region’s agricultural and industrial goods, and heavily used by the recreation and tourism industries, the Hudson plays a major role in the local economy. It also provides drinking water for more than 100,000 people.

At the end of the American Revolution, the population in the Hudson River Valley began to grow. The introduction of railroad travel in 1851 further accelerated development in the area. Industrial buildings were erected along the river, such as brick and cement manufacturing, which was followed by residential building. Along with the aforementioned development, came the construction of approximately 1,600 dams and thousands of culverts throughout the Hudson River.

According to the U.S. Army Corps of Engineers (USACE), these human activities have significantly degraded the integrity of the Hudson River ecosystem and cumulatively changed the morphology and hydrology of the river. Over time, these changes have resulted in large-scale losses of critical shallow water and intertidal wetland habitats, and fragmented and disconnected habitats for migratory and other species. Most of this loss and impact has occurred in the upper third portion of the estuary.

As part of the effort to restore the vital river ecosystem, the USACE New York District launched a Hudson River Habitat Restoration Feasibility Study, which helps to establish and evaluate baseline conditions, develop restoration goals and objectives, and identify key restoration opportunities. Princeton Hydro participated in data collection and analysis, conceptual restoration designs, and preparation of the USACE Environmental Assessment for the Hudson River Habitat Restoration Ecosystem Restoration Draft Integrated Feasibility Study and Environmental Assessment.

Basic map depicting project sites (Created by Princeton Hydro)The study area includes the Hudson River Valley from the Governor Mario M. Cuomo Bridge downstream to the Troy Lock and Dam upstream. The primary restoration objectives include restoring a mosaic of interconnected, large river habitats and restoring lost connectivity between the Hudson River and adjacent ecosystems.

A total of six sites were evaluated using topographic surveys, installation and monitoring of tide gauges, evaluation of dam and fish barrier infrastructure, and field data collection and analysis to support Evaluation of Planned Wetlands (EPW) and Habitat Suitability Indices (HSI) functional assessment models. Literature reviews were also completed for geotechnical, hazardous toxicity radioactive waste, and aquatic organism passage measures.

Multiple alternatives for each of the six sites were created in addition to the preparation of conceptual designs, quantity take-offs, and cost estimates for construction, monitoring and adaptive management, and long-term operation and maintenance activities.

Princeton Hydro also prepared an environmental assessment in accordance with NEPA standards, addressing all six sites along the Hudson River and its tributaries. This assessment served to characterize existing conditions, environmental impacts of the preferred Proposed Action and No Action Alternatives, and regional cumulative environmental impacts. Our final report was highlighted by USACE at the 2019 Planning Community of Practice (PCoP) national workshop at the Kansas City District as an example of a successfully implemented Ecosystem Restoration Planning Center of Expertise (ECO-PCX) project.

USACE’s specific interest in Hudson River restoration stems from the aforementioned dramatic losses of regional ecosystems, the national significance of those ecosystems, and the apparent and significant opportunity for measurable improvement to the degraded ecological resources in the river basin.

The feasibility study is among the first of several critical steps in restoring the Hudson River’s ecosystem function and dynamic processes, and reestablishing the attributes of a natural, functioning, and self-regulated river system. Stay tuned for more updates on the Hudson River restoration efforts.

Flipping the Script on American Environmental Thought: FREE Presentation Download

 

The Watershed Institute held its 3rd Annual New Jersey Watershed Conference, an educational event that aims to advance knowledge and communications on issues related to water quality and quantity across the state. The event included a variety of presentations from local experts on watershed management, stormwater, and problems and solutions related to the health of New Jersey’s watersheds.

During the conference, Princeton Hydro’s Marketing Coordinator Kelsey Mattison, a St. Lawrence University graduate with a degree in English and environmental studies, lead a workshop that explored binaries in environmental thought and how to break through those limiting thought processes in order to advance a more productive and shared understanding of our natural world.

The presentation, titled “Flipping the Script on American Environmental Thought,” discussed how black-and-white thought processes (a.k.a. binaries) cause us to view issues as one or the other, leaving little to no room for the possibility of blending the two.

Historically, American thought has viewed environmental issues through a binary lens: either we favor human society, or we favor the environment, and this juxtaposition has rarely allowed for integration between the two perspectives.

Take, for example, the two concepts of preservation and conservation toted by John Muir and Gifford Pinchot, respectively. Muir’s concept of preservation argued that humans should set land aside to leave untouched to preserve its natural beauty, while Pinchot’s concept of conservation advocated for a responsible use of the land’s resources. Both are forms of environmental advocacy, but neither leave much room to combine the two ideas, ultimately creating a black and white binary surrounding human responsibility to the planet. This makes it difficult to then make any compromise on issues related to managing or utilizing our natural resources.

The workshop also explored answers to the important question of: “How do we flip the script to be more inclusive?” Participants discussed ideas around utilizing Values-Based Communication in order to connect with people from different groups/with different values. A few of the communication strategies Kelsey presented, include:

  • Finding Common Ground:

    When groups are telling such different narratives, it can be hard to see that their goals might actually be completely in line. By first identifying what each group’s priorities are, we can better understand their needs in order to help fulfill them. This allows people with seemingly conflicting beliefs to work towards a common goal.

  • Seeing More than Two Sides:

    Generally, people default to thinking there are only two sides to an issue, but no conflict is ever truly just one thing or the other. Even if there are overtly two options, the issue is always more complex. When resolving conflict, it’s almost always possible to find at least one thing the two sides have in common.

Overall, Kelsey’s workshop emphasized the importance of open-mindedness and inclusion in our approach to environmental action in order to bring people together and foster real change. If you’re interested in learning more, click here for a free download of Kelsey’s full presentation.

The New Jersey Watershed Conference, of which Princeton Hydro was a sponsor and exhibitor, also included presentations on topics ranging from urban flooding to microplastics in our waterways to green infrastructure. Dr. Fred Lubnow, Princeton Hydro’s Director of Aquatic Programs, presented on the “Causes and Impacts of Harmful Algal Blooms.” To view the complete agenda, go here.

Princeton Hydro is a proud supporter of The Watershed Institute, a nonprofit organization comprised of policy advocates, scientists, land and water stewards, naturalists, and educators. Focused on the Central New Jersey area, the Watershed Institute speaks out for water and environment, protects and restores sensitive habitats, tests waterways for pollution, and inspires others to care for the natural world. For more information, or to become a member, go here.

Identifying, Understanding and Addressing Harmful Algae Blooms

Harmful Algae Bloom Visible in Owasco Lake. Photo by: Tim Schneider

Harmful Algae Blooms (HABs) were in the spotlight this summer due to the severe impacts they had on lakes throughout the country. The nation-wide HABs outbreak caused beach closures, restricted access to lake usage, and wide-ranging health advisories.

What exactly are HABs? Why were they so severe this summer? Will this trend continue? Can anything be done to prevent the occurrence or mitigate the impacts?

In this blog, we provide answers to all of those questions, exploring what HABs are, why they occur, why they were particularly prevalent this summer, and what we can do to combat them.

What are HABs?

Simply put, HABs are rapid, large overgrowths of cyanobacteria. Cyanobacteria, also known as blue-green algae, aren’t actually algae, they are prokaryotes, single-celled aquatic organisms that are closely related to bacteria and can photosynthesize like algae. These microorganisms are a natural part of aquatic ecosystems, but, under the right conditions (primarily heavy rains, followed by hot, sunny days), these organisms can rapidly increase to form cyanobacteria blooms, also known as HABs.

HABs can cause significant water quality issues in lakes and ponds, often forming a visible and sometimes odorous scum on the surface of the water. They can produce toxins that are incredibly harmful (even deadly) to humans, animals, and aquatic organisms. HABs also negatively impact economic health, especially for communities dependent on the income of jobs and tourism generated through their local lakes and waterways.

What causes HABs?

HABs are caused by a complex set of conditions, and many questions remain about exactly why they occur and how to predict their timing, duration, and toxicity. Primarily, HABs are caused by warmer temperatures and stormwater run-off pollutants, including fertilizers with phosphates.

NY Times article, featuring Princeton Hydro, looks at how climate change affects lakes nationwide, using NJ as an example. Photo by: Rick Loomis, NY Times.HABs are induced by an overabundance of nutrients in the water. The two most common nutrients are fixed nitrogen (nitrates and ammonia) and phosphorus. Discharges from wastewater treatment plants, runoff from agricultural operations, excessive fertilizer use in urban/suburban areas, and stormwater runoff can carry nitrogen and phosphorus into waterways and promote the growth of cyanobacteria.

Climate change is also a factor in HAB outbreaks, which typically occur when there are heavy rains followed by high temperatures and sunshine. Climate change is leading to more frequent, more intense rainstorms that drive run-off pollutants into waterways, coupled with more hot days to warm the water. These are the ideal conditions for HABs, which in recent years have appeared in more places, earlier in the summer.

With climate change and increasing nutrient pollution causing HABs to occur more often and in locations not previously affected, it’s important for us to learn as much as we can about HABs so that we can reduce their harmful effects.

What Can I Do to Prevent HABs?

Signs on the closed beach at Hopatcong State Park warn residents of the Harmful Algae Bloom at Lake Hopatcong on July 2019, in Landing, NJ. (Photo by: Danielle Parhizkaran of NorthJersey.comThe number one thing individuals can do to protect their waterbodies and prevent HABs is to reduce phosphorous use and reduce nutrient loads to waters.

According to Dr. Fred Lubnow, Director of Aquatic Programs for Princeton Hydro, “Managing loads of phosphorous in watersheds is even more important as the East Coast becomes increasingly warmer and wetter thanks to climate change. Climate change will likely need to be dealt with on a national and international scale. But local communities, groups, and individuals can have a real impact in reducing phosphorous levels in local waters.”

Here are a few steps you can take to improve water quality in your community lakes:

Controlling stormwater runoff is another critical factor in improving water quality and reducing HABs. There are a number of low-cost green infrastructure techniques that can be implemented on an individual and community-wide scale. You can read more about green infrastructure stormwater management techniques in our recent blog.

In a recent Op/Ed published on NJ.com, Princeton Hydro President Geoff Goll lists four things that residents, businesses, and local governments should do to prevent another HABs outbreak next summer:

  1. Improve aging “gray” infrastructure
  2. Invest in “green” stormwater infrastructure
  3. Implement regional/watershed-based planning
  4. Pass the Water Quality Protection and Jobs Creation Act

“By making the necessary investments, we can simultaneously create jobs, reduce flood impacts, improve fisheries, maintain or increase lakefront property values, improve water quality and preserve our water-based tourism. The time to act is literally now,” said Geoff. Go here, to read the full article.

HABs Management in Action through Floating Wetland Islands:

Nitrogen and phosphorus are utilized by plants, which means they uptake these nutrients to sustain growth. We see this naturally occurring in wetland ecosystems where wetlands act as a natural water filtration system and can actually thrive from nutrients flowing in from external sources.

This process is replicated in floating wetland islands (FWIs), where you typically have a constructed floating mat with vegetation planted directly into the material. The plants then grow on the island, rooting through the floating mat.

This illustration, created by Staff Scientist Ivy Babson, conveys the functionality of a Floating Wetland Island

This illustration, created by Staff Scientist Ivy Babson, conveys the functionality of a Floating Wetland Island

Not only do FWIs assimilate and remove excess nitrogen and phosphorus out of the water, they also provide habitat for fish and other aquatic organisms; help mitigate wave and wind erosion impacts; provide an aesthetic element; and can be part of a holistic lake/pond management strategy. Because of this, FWIs are being utilized to improve water quality and control HABs in lakes and ponds throughout the country. Princeton Hydro has designed and implemented numerous FWIs in waterbodies large and small. Go here to learn how they’re being used in Harveys Lake.

 

Recognizing and monitoring the changes that are taking place in our local waterways brings the problems of climate change, stormwater pollution and the resulting water quality issues closer to home, which can help raise awareness, inspire environmentally-minded action and promote positive, noticeable change.

If you spot what you believe to be a harmful algae bloom in your community lake, contact your local lake association right away. They, along with their lake management team, can assess the situation and determine what further actions need to be taken.

For more information about harmful algae blooms and water quality management, go here: http://bit.ly/pondlake.

Special thanks to Princeton Hydro Staff Scientist Ivy Babson for her contributions to this blog.

Don’t Get Sunk: Everything You Need to Know About Sinkholes (Part Two)

Sinkhole in Frederick, Maryland. Credit: Randall Orndorff, U.S. Geological Survey. Public domain.

Sinkholes can be quite terrifying. We see them on the news, on television and in movies seemingly appearing out of nowhere, swallowing up cars and creating calamity in towns across the world. In this two-part blog series, our experts uncover the mystery around sinkholes and arm you with the facts you need to make them less scary.

In part one of the blog series, we discuss what a sinkhole is, three different types of sinkholes, and what causes them to form. In this second part, we explore how to detect sinkholes, what to do if you detect a sinkhole, and the steps taken to repair them.

WELCOME TO PART TWO: DON’T GET SUNK: EVERYTHING YOU NEED TO KNOW ABOUT SINKHOLES
How to Detect a Sinkhole:

Cover-collapse sinkholes (outlined in red) in eastern Bullitt County Kentucky. Photo by Bart Davidson, Kentucky Geological Survey.Not all sinkholes are Hollywood-style monstrosities capable of swallowing your whole house. But even a much smaller, less noticeable sinkhole can do its fair share of harm, compromising your foundation and damaging utilities.

Although sinkholes can be scary to think about, you can take comfort in knowing there are ways to detect them, both visually and experimentally. Often, you can spot the effects of a developing sinkhole before you can spot the hole itself. If you live in an area with characteristics common to sinkhole formation (i.e. “karst terrain,” or types of rocks that can easily be dissolved by groundwater), there are some things you can do to check your property for signs of potential sinkhole formation.

According to the American Society of Home Inspectors, there are key signs you should be on the lookout for in and around your home:

Inside:

  • structural cracks in walls and floors;
  • muddy or cloudy well water;
  • interrupted plumbing or electrical service to a building or neighborhood due to damaged utility lines; and
  • doors and windows that don’t close properly, which may be the result of movement of the building’s foundation.

Outside:

  • previously buried items, such as foundations, fence posts, and trees becoming exposed as the ground sinks;
  • localized subsidence or depression anywhere on the property; in other words, an area that has dropped down relative to the surrounding land;
  • gullies and areas of bare soil, which are formed as soil is carried towards the sinkhole;
  • a circular pattern of ground cracks around the sinking area;
  • localized, gradual ground settling;
  • formation of small ponds, as rainfall accumulates in new areas;
  • slumping or falling trees or fence posts; and
  • sudden ground openings or ground settlement, keeping in mind that sudden earth cracking should be interpreted as a very serious risk of sinkhole or earth collapse.
Actions to Take if You Believe You’ve Detected a Sinkhole:

If you spot any of the signs listed above, or you suspect that you have a sinkhole on or near your property, you should contact your township, public works, or the local engineering firm that represents your municipality right away. If you have discovered a sinkhole that is threatening your house or another structure, be sure to get out immediately to avoid a potentially dangerous situation.

Also, it is highly recommended that:

  • Credit: USGSIf a sinkhole expert can’t get to the area relatively quickly, you ensure that kids and animals keep away, fence/rope-off the area while maintaining a far distance away from the actual sinkhole, keeping in mind that doing so requires extreme caution and is always best left to the experts when possible;
  • Notify your neighbors, local Water Management District, and HOA;
  • Take photos to document the site;
  • Remove trash and debris from around the suspected area in order; and
  • Keep detailed records of all the actions you took.

If you’re trying to determine whether or not you have a sinkhole on your property, there are a few physical tests that can be conducted to determine the best course of action.

In Australia, a courtyard formed a sinkhole. Credit: Earth-Chronicles.comElectro-resistivity testing: This extremely technical test can best be summed up by saying it uses electrodes to determine the conductivity of the soil. Since electricity can’t pass through air, this test shows any pockets where the current didn’t pass through. This is a fairly accurate way to determine if there is a sinkhole and where it is.

Micro-gravity testing: Another incredibly technical method, this test uses sensors that detect the measure of gravity. Since the gravitational pull in a given area should be the same, you can see if there are minute differences in the measurement. If there is a difference, then it’s likely that you have a sinkhole in that area.

If you are still unsure whether or not you live in a sinkhole risk area, you can check with your local, territorial, or national government offices; review geological surveys such as the United States Geological Survey (USGS); and contact an expert.

How a Sinkhole is Repaired?

There are three main techniques experts utilize to repair sinkholes. The type of sinkhole and landowner’s aesthetic preferences determine the methodology used to repair the sinkhole.

The three common methods are:

  1. Inject grout with a drill rig: This uses a piece of large drilling equipment that pierces the ground and goes down into the sinkhole, injecting it with grout/concrete. This method stops the filling of the carbonate crack with sediment since concrete and grout do not break down into such small particles (no piping).
  2. Inverted cone: With this method, the construction crew digs down and finds the bowl-shaped opening. They then open up the surface so that the entire sinkhole area is exposed. To stop the draining of sediment into the crack in the carbonate rock, they fill the hole with bigger rocks first, then gradually fill in the seams with smaller rocks until the sinkhole is plugged.
  3. Filling it with concrete/grout from the surface: This is a combination of the prior two methods. The construction crew opens the surface all the way up so the entire hole is exposed. Then, they bring in a big concrete pourer and fill the sinkhole with concrete.

Missouri Dept of Natural Resources, Inverted cone repair sinkhole mitigation diagram

Our engineers regularly go out in the field to oversee and inspect sinkhole repairs. If you detect a sinkhole, or what might be a sinkhole, on your property, our experts strongly advise immediate actions be taken. Ignoring a sinkhole will only cause it to get larger and more dangerous as time passes, and putting topsoil over a sinkhole will only exacerbate the symptoms.

What Can You Do to Prepare for a Sinkhole?

While there’s really no way to prevent a sinkhole, you can never be too prepared! Here are three easy steps you can take to determine if you live in or around a sinkhole-prone area and what to do in the event of a surprise sinkhole:

  1. Find out whether or not you’re living in one of the sinkhole-prone states, which includes Pennsylvania, Texas, Florida, Alabama, Tennessee, and Missouri. You can do so by visiting USGS.com and searching for Bedrock Geology maps of your area. If your town is underlain by carbonate rocks, you are likely in a sink-hole prone area.
  2. Contact an engineer who’s certified to deal with sinkholes to determine if your property is at-risk.
  3. Develop a plan for what to do in the event of a sinkhole. Do you grab your family, pets, and leave immediately? Do you have a safe zone somewhere near (but not too near) your property? Do you have the appropriate emergency contact numbers in your phone? Does your car have a safety kit? These are some of the things to consider when making your emergency plan.
  4. Speak with your insurance company to see if they have sinkhole coverage, especially if you live in an area where they’re known to occur.

Although scary, sinkholes are a manageable threat if you’re informed and prepared. After all, it is possible to do something about sinkholes – if they can be detected in time.

Special thanks to Princeton Hydro Staff Engineer Stephen Duda, Geologist Marshall Thomas, and Communications Intern Rebecca Burrell for their assistance in developing this blog series.

Revisit Part One of this blog series in which we provide a detailed look at what a sinkhole is, three different types of sinkholes, and what causes them to form:

Don’t Get Sunk: Everything You Need to Know About Sinkholes (Part One)

Delaware River Watershed Forum Participants Tour Musconetcong River Dam Removals

The 7th Annual Delaware River Watershed Forum, a two-day conference hosted by The Coalition for the Delaware River Watershed, brought together organizations, consultants, and individuals spanning the four watershed states of PA, NY, NJ, and DE. This year’s Forum included presentations, interactive discussions, capacity-building workshops, and site visits that highlighted local conservation projects.

One of the site visits, led by Musconetcong Watershed Association (MWA) Executive Director Alan Hunt, toured dam removal sites along the Musconetcong River. The field trip visited the Finesville Historic District, where a dam was removed in 2012, and the village of Warren Glen, where the Hughesville dam was removed in 2016. Trip participants heard from project partners including Princeton Hydro President Geoff Goll, P.E., Beth Styler Barry of New Jersey Nature Conservancy,  Dale Bentz of RiverLogic Solutions, Beth Frieday of U.S. Fish and Wildlife Service, Jacob Helminiak of U.S Army Corps of Engineers, and Christine Hall of USDA Natural Resources Conservation Service.

“We really appreciate everyone who, despite the rainy weather, participated in the Musconetcong River Restoration field trip to learn about how dam removals are helping to restore the river back to it’s natural free-flowing state and the numerous resulting environmental benefits,” said Geoff. “This river restoration work exemplifies how a diverse group of public and private entities can work together to overcome challenges and achieve tremendous success.”

Princeton Hydro President Geoff Goll, P.E. provides field trip participants with information about the Hughesville Dam removal project and the adaptive management work currently happening at the site.Princeton Hydro has been working with MWA in the areas of river restoration, dam removal, and engineering consulting since 2003, when the efforts to remove the Gruendyke Mill Dam in Hackettstown, NJ began. To date, Princeton Hydro has investigated, designed, and permitted five dam removals along the Musconetcong River, the most recent being the Hughesville Dam. This 16’ dam was removed in 2016 and, one year later in 2017, American Shad returned to the site for the first time in at least 100 years, and the removal was credited by the State as a contributing factor for the increase in Delaware River shad population. There is an ongoing project to monitor fishery and aquatic habitat recovery at the site. The next Musconetcong dam targeted for removal is the 32-foot high Warren Glen Dam. It is the largest dam in the river; by comparison, the Hughesville Dam was 15-feet tall.

The Coalition for the Delaware River Watershed was formed in 2012, the Coalition works to raise awareness of the river and its surrounding landscape by bringing together groups already working to restore degraded resources, safeguard vulnerable assets, and educate their communities. The Coalition is committed to protecting and restoring the Delaware River, its tributaries, and more than 13,500 square miles of forests, wetlands, communities, and other distinctive landscapes in the watershed so that clean water and valued resources are secured for generations to come.

MWA is an independent, non-profit organization dedicated to protecting and improving the quality of the Musconetcong River and its Watershed, including its natural and cultural resources. Members of the organization are part of a network of individuals, families and companies that care about the Musconetcong River and its Watershed, and are dedicated to improving the watershed resources through public education and awareness programs, river water quality monitoring, promotion of sustainable land management practices and community involvement.

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of dozens of small and large dams in the Northeast. To learn more about our fish passage and dam removal engineering services, visit: bit.ly/DamBarrier. To learn more about our Musconetcong River restoration work, go here:

The Return of the American Shad to the Musconetcong River

 

 

Laura Wildman Awarded for “Bringing the Presumpscot River Back to Life”

Photo provided by the Friends of the Presumpscot River

The Friends of the Presumpscot River (The Friends) Board of Trustees awarded Laura Wildman, P.E., Princeton Hydro’s New England Regional Office Director and Water Resources and Fisheries Engineer, with its “Chief Polin Award.” The award recognizes Laura for her accomplishments and efforts in bringing life back to the Presumpscot River and rivers across the nation. The award was presented at The Friends’ Three Sisters Harvest Dinner & Annual Celebration.

The Chief Polin Award recognizes those who are making significant efforts to restore fish passage, improve water quality and bring back the natural character of the Presumpscot river.During her acceptance speech, Laura thanked The Friends for its continued dedication to restoring fish passage and revitalizing the river. “I am so proud to be part of the ‘river warriors’ team,” Laura said. “Our collective efforts to protect and restore the river have resulted in invaluable benefits to fish, aquatic organisms, wildlife, and the surrounding communities.”

The award is named after local Abanaki tribe leader Chief Polin, who led the first documented dam protest in New England during the mid-1700s, advocating for fish passage, which had been compromised by the first dams built along the river. The award recognizes those who are making significant efforts to restore fish passage, improve water quality, and bring back the natural character of the Presumpscot River. Sean Mahoney from the Conservation Law Foundation also received the Chief Polin Award during the Annual Celebration.

Map provided by The Friends of the Presumpscot RiverLocated in Cumberland County, Maine, the Presumpscot is a 25.8-mile-long river and the largest freshwater input into Casco Bay. The river has long been recognized for its vast quantity of fish. According to The Friends, when Europeans first arrived, they reported that “the entire surface of the river, for a foot deep, was all fish.”

In the 1730s, however, the construction of dams halted the passage of fish up the river. As more dams sprung up in the following centuries, the ecological vitality of the river steadily declined.

For more than 250 years, people have advocated for the unobstructed passage of fish up the Presumpscot River. Over the last 50 years, the river has undergone profound transformation due to the enactment of the Clean Water Act, the removal of a few dams, and the installation of fish passages on existing dams. Fish passage at Cumberland Mills Dam, which was completed in 2013, restored critical habitat to sea run fish such as shad, American eel, and river herring, and allowed them to move upstream again.

Saccarappa Falls dam removal in actionIn July, work began to restore a large reach of the river through Westbrook, Maine. The project involves the removal of two dam spillways from the upper Saccarappa Falls and the construction of a fishway around the lower falls. The project, which was three years in the making, was finally approved to move forward once the City of Westbrook, Sappi Fine Paper, the U.S. Fish and Wildlife Service, the Maine Department of Marine Resources, and the nonprofits, Friends of the Presumpscot River and Conservation Law Foundation, were able to reach a ground breaking settlement. The Saccarappa Falls project is a major step in restoring the river and was a focal point of the Three Sisters Harvest Dinner, celebrating decades of effort on the parts of the Friends of the Presumpscot along with their numerous project partners, including Princeton Hydro.

About the Friends of the Presumpscot River: A nonprofit organization founded in 1992, supported primarily by membership dues and small donations. Its mission is to protect and improve the water quality, indigenous fisheries, recreational opportunities and natural character of the Presumpscot River.
Learn more: presumpscotriver.org

About Princeton Hydro: Princeton Hydro has designed, permitted, and overseen the removal of dozens of small and large dams along the East Coast. To learn more about our fish passage and dam removal engineering services, visit: bit.ly/DamBarrier.

Sediment Testing on the St. Lawrence Seaway

Way up in Northern New York, the St. Lawrence River splits the state’s North Country region and Canada, historically acting as an incredibly important resource for navigation, trade, and  recreation. Along the St. Lawrence River is the St. Lawrence Seaway, a system of locks, canals, and channels in both Canada and the U.S. that allows oceangoing vessels to travel from the Atlantic Ocean all the way to the Great Lakes.

Recently, the St. Lawrence Seaway Development Corporation (SLSDC) contracted Princeton Hydro to conduct analytical and geotechnical sampling on material they plan to dredge out of the Wiley-Dondero Canal. Before dredging, sediment and soils have to be tested to ensure their content is suitable for beneficial reuse of dredged material. In August, our Geologist, Marshall Thomas and Environmental Scientist, Pat Rose, took a trip up north to conduct soil sampling and testing at two different sites within the canal near Massena and the Eisenhower Lock, which were designated by the SLSDC. The first site was at the SLSDC Marine Base, which is a tug/mooring area directly southwest of Snell Lock. The second location was directly northeast of the Eisenhower Lock, which is also used as a mooring area. Both of these sites require dredging in order to maintain mooring access for boat traffic navigating the channel.

During this two-day sampling event, our team, which also included two licensed drillers from Atlantic Testing Laboratories, used a variety of equipment to extract the necessary samples from the riverbed. Some of the sampling equipment included:

  • Vibracoring equipment: this sampling apparatus was assembled on Atlantic Testing’s pontoon boat. To set up the vibracore, a long metal casing tube was mounted on the boat more than 10 feet in the air. The steel casing was lowered through the water approximately 17-20 feet down to the mudline. From there, the vibracore was then vibrated through the sediment for an additional 4-6 feet. For this project, vibracore samples were taken at 4 feet in 10 different locations, and at 6 feet in 3 different locations.

  • A track mounted drill rig: this rig was positioned along the shoreline to allow advancement of a standard geotechnical test boring close to existing sheet piling. Advancement of the boring was done by way of a 6-inch hollow stem auger. As the auger was advanced, it resembled a giant screw getting twisted into the ground. This drilling method allows the drilling crew to collect soil samples using a split spoon sampler, which is a 2-foot long tubular sample collection device that is split down the middle. The samplers were collected by driving the split spoon into the soil using a 140 lb drop hammer.

For our team, conducting sampling work on the St. Lawrence Seaway was a new experience, given most of our projects occur further east in the Mid-Atlantic region. The most notable difference was the hardness of the sediment. Because the St. Lawrence River sediments contain poorly sorted, dense glacial till, augering into it took a little more elbow grease than typical sediments further south do.  The St. Lawrence River is situated within a geological depression that was once occupied by glaciers. As the glaciers retreated, they were eventually replaced by the Champlain Sea, which flooded the area between 13,000 and 9,500 years ago. Later on, the continent underwent a slight uplift, ultimately creating a riverlike watercourse that we now deem the St. Lawrence River. Because it was once occupied by a glacier, this region is full of glacial deposits.

For this project, our team was tasked with collecting both geotechnical and analytical samples for physical and analytical testing. Physical testing included grain size analysis, moisture content, and Atterberg limit testing. Grain size analysis helps determine the distribution of particle sizes of the sample in order to classify the material, moisture content testing determines exactly that — how moist the sediment is, and Atterberg limits help to classify the fines content of the materials as either silt or clay. Analytical testing included heavy metals, pesticides, volatile organic compounds, and dioxins.

Our scientists were responsible for logging, testing, and providing a thorough analysis of fourteen sampling locations. The samples collected from the vibracore tubes filled with sediment were logged and spilt on-shore. In order to maintain a high level of safety due to the possible presence of contaminants, all of the sampling equipment was decontaminated. This process involves washing everything with a soapy water mixture, a methanol solution, and 10% nitric acid solution.

The samples collected at each vibrocore location were split into multiple jars for both analytical and physical testing. The physical test samples were placed into air and moisture tight glass sample jars and brought to our AASHTO accredited soils laboratory in Sicklerville, New Jersey for testing. The analytical samples were placed into airtight glass sample jars with Teflon-lined caps. These samples were then placed into an ice-filled cooler and sent to Alpha Analytical Laboratories for the necessary analytical testing.

Once all the laboratory testing was completed, a summary report was developed and presented to the client. This report was made to inform the SLSDC of the physical properties of each sediment sample tested and whether contaminants exceeded threshold concentrations as outlined in the New York State Department of Environmental Conservation (NYSDEC) Technical & Operation Guidance Series (TOGS) 5.1.9. This data will ultimately be used by the SLSDC to determine the proper method for dredging of the material and how to properly dispose of the material.

Princeton Hydro provides soil, geologic, and construction materials testing to both complement its water resources and ecological restoration projects and as a stand-alone service to clients. Our state-of-the-art Soils Testing Laboratory is AASHTO-accredited to complete a full suite of soil, rock, and construction material testing for all types of projects. For more information, go here: http://bit.ly/2IwqYfG 

Don’t Get Sunk: Everything You Need to Know About Sinkholes (Part One)

Photo by Steven Reilly/New Jersey Herald

Sinkholes are a phenomenon that tend to baffle and frighten most people. How is it possible that the ground beneath our feet could just drop? How do we know if we’re nearby a sinkhole? What should we do if we see one? How are sinkholes fixed? The mystery of the unknown around sinkholes can be quite unnerving.

Have no fear, we’ve got answers to all of those questions and more! In this two-part blog series, our experts share their knowledge and provide important information about this scary occurrence. In part one, we provide a detailed look at what a sinkhole is, three different types of sinkholes, and what causes them to form. In part two, we explore how to detect sinkholes and the steps taken to repair them.

What is a Sinkhole?

Sinkholes are a common phenomenon around the world. They result from both man-made and natural causes. Marshall Thomas, a Princeton Hydro geologist, describes sinkholes as “depressions observed from the surface, caused by dissolution of carbonate rocks.” In other words, sinkholes form when the rock below the land surface gets dissolved by water that penetrates the surface and continues to move downward, further into the subsurface.

Most common in areas with “karst terrain,” or types of rocks that can easily be dissolved by groundwater, sinkholes can go undetected for years until the space underneath the surface gets too big or enough of the surface soil is washed away. Sometimes the holes are small, measuring a few feet wide and ten feet deep. Sometimes the holes are hundreds of miles wide and deep. However, all of them can be dangerous.

Sinkholes are found throughout the world. States like Pennsylvania, Texas, Florida, Alabama, Tennessee, and Missouri are at higher risk for sinkholes because they tend to have more soluble rocks like salt beds and domes, gypsum, limestone, and other carbonate rocks. People living in these states are recommended to have professionals look at any property they intend to buy to make sure it isn’t in an area above soluble rock.

Types of Sinkholes

Not all sinkholes are the scary, earth-falling-out-from-underneath-your-feet events. Some occur slowly over time and are very evident from the surface. Geologists classify sinkholes in three major types. Their formation is determined by the same geological processes, barring a few differences. Let’s dive in!

1. Dissolution Sinkholes

Illustration by USGSDissolution sinkholes start to form when limestone or dolomite is very close to the soil surface, usually covered by a thin layer of soil and permeable sand which washes away or is eroded. Rain and stormwater runoff gradually percolate through crevices in the rock, dissolving it. Consequently, a bowl-shaped depression slowly forms.

Sometimes, dissolution sinkholes become ponds when the depression gets lined with debris, which traps water inside. Dissolution sinkholes develop gradually and are normally not dangerous. However, the ones that become ponds can drain abruptly if water breaks through the protective bottom layer.

Fun fact: Most of Florida’s lakes are actually just large sinkholes that filled up with water!

2. Cover-Subsidence Sinkholes

Illustration by USGSThis type of sinkhole, which starts with the dissolution of the underlying carbonate bedrock, occurs where the covering sediment is permeable (water can pass through it) and contains sand. First, small pieces of sediment split into smaller pieces and fall into openings in the carbonate rock underneath the surface. With time, in a process called piping, the small particles settle into the open spaces. This continues, eventually forming a dip in the surface ranging from one inch to several feet in depth and diameter. Again, these aren’t the sinkholes movies are made about.

3. Cover-Collapse Sinkholes

Illustration by USGSThis type of sinkhole is the one making headlines and causing fear. In order for cover-collapse sinkholes to happen, the covering soil has to be cohesive, contain a lot of clay and the bedrock has to be carbonate. Similar to the cover-subsidence sinkholes, the cohesive soil erodes into a cavity in the bedrock. The difference with this is that the clay-filled top surface appears to remain intact from above. However, underneath, a hollowed out, upside down bowl shape forms. That hollowing gets bigger and bigger over time until eventually, the cavity reaches the ground surface, causing the sudden and dramatic collapse of the ground. Just like that, poof, we have a sinkhole that appears to be surprising and abrupt but really has been brewing for many years.

What Causes a Sinkhole?

Sinkholes can be natural or man-made. The most common causes of a sinkhole are changes in groundwater levels or a sudden increase in surface water.

Intensive rain events can increase the likelihood of a sinkhole collapse. Alternatively, drought, which  causes groundwater levels to significantly decrease, can also lead to a greater risk of collapse of the ground above. In a world with a greater variability in rainfall and drought events due to climate change, sinkholes may become a more common occurrence around the world.

Humans are also responsible for the formation of sinkholes. Activities like drilling, mining, construction, broken water or drain pipes, improperly compacted soil after excavation work, or even significantly heavy traffic (heavy weight on soft soil) can result in small to large sinkholes. Water from broken pipes can penetrate through mud and rocks and erode the ground underneath and cause sinkholes.

Most commonly, human-caused sinkholes are the result of:

  • Land-use practices like groundwater pumping, construction, and development
  • Changing of natural water-drainage patterns
  • Development of new water-diversion systems
  • Major land surface changes, causing substantial weight changes

In some cases, human-induced sinkholes occur when an already forming sinkhole is encountered during construction processes such as excavation for stormwater basins and foundations. Dissolution of bedrock generally occurs in geologic time-frames (thousands of years). In these cases, the excavation process has removed the covering soils, decreasing the distance between the top of the void and the ground surface.  

In other cases, voids in the bedrock are generated due to rock removal processes such as hammering and blasting. Hammering and blasting can generate fractures or cracks in the bedrock that soil can then erode into. A void in the bedrock may already exist, however, the process of removing the bedrock by hammering and/or blasting can speed up the meeting of the upside-down bowl and the surface that much quicker. One site where this happened has experienced over 35 sinkholes in 4 years.

Overall, it’s generally not a good idea to pump groundwater or do major excavation in areas that are prone to sinkholes. According to the USGS, over the last 15 years sinkhole damages have cost on average at least $300 million per year. Because there is no national tracking of sinkhole damage costs, this estimate is probably much lower than the actual cost. Being more mindful about the subsurface around us and our actions could help lower the average yearly cost in damages and even save lives.

Photo by Barbara Miller PennLive Patriot News

Stay tuned for Part Two of this blog series in which we explore we explore how to detect sinkholes and the steps taken to repair them! For more information about Princeton Hydro’s Geotechnical Engineering services, go here: http://bit.ly/PHGeotech

Special thanks to Princeton Hydro Staff Engineer Stephen Duda, Geologist Marshall Thomas, and Communications Intern Rebecca Burrell for their assistance in developing this blog series.

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