About phadmin

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.

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.

Sources:

Employee Spotlight: Meet Our New Team Members

We’re excited to announce the hiring of a new employee and the promotion of a member of our Field Operations team.

 

Jennifer Duff, Administrative Assistant

Jennifer works in our Glastonbury, CT location assisting with office coordination and administrative tasks. She is skilled in data visualization and graphic design, and enjoys working with our wonderful team of scientists, engineers, specialists, and people passionate about the environment and outdoors.

In her free time, she enjoys hiking, kayaking, crafting, and design. She is also passionate about local land and fiber, and spends time knitting and organizing wool farmers in the region.

Jacob Pigman, Aquatic Specialist

Jacob began with Princeton Hydro as a part-time staffer and is now a full-time member of the Aquatics Field Services Practice Area. His daily responsibilities include a variety of field tasks, including the treatment of lakes and ponds for hazardous algal blooms, the treatment/removal of invasive plant species, and the installation of fountain and/or aeration systems for sustainable water management. Working on the field operations team has given Jacob an opportunity to learn about the environmental science field, and he hopes to continue to grow his experience into a successful and bright future with the firm.

Born and raised at the Jersey Shore, Jacob enjoys spending time at the beach. He also enjoys cooking.

 

Learn more about our team.

 

 

 

DIY: Protecting Water Quality in Your Community

There are lots of things we can do to preserve our precious water resources. Reducing stormwater pollution in our neighborhoods is something everyone can take part in. Storm drain cleaning is a great place to start!

DIY Storm Drain Cleaning

Urbanization has fundamentally altered the way that water moves through the landscape. Stormwater that doesn’t soak into the ground runs along streets and parking lots and picks up pollutants. Much of the pollution in our nation’s waterways comes from everyday materials like fertilizers, pesticides, motor oil, and household chemicals. Rainwater washes these substances from streets, yards and driveways into storm drains.

It’s a common misconception that storm drains lead to wastewater treatment plants. In actuality, storm drains rarely lead to treatment plants and instead stormwater systems carry untreated water directly to the nearest waterway. This polluted runoff can have negative impacts on water quality, overstimulate algal growth (both toxic and non-toxic), harm aquatic species and wildlife, and cause trash and debris to enter our lakes, streams, rivers and oceans.

https://www.middlesexcentre.on.ca/Public/Stormwater

We can all do our part to improve and preserve water resources in our community and beyond!

Keeping neighborhood storm drains cleaned is one simple step. Removing debris that collects in nearby stormwater catch basins, storm drains and along curbs promotes cleaner runoff, reduces the potential for flooding, and decreases the amount of pollution and trash entering our waterways.

Follow these simple steps for DIY storm drain cleaning:

  1. Photo: Santiago Mejia, The ChronicleRake/sweep and discard debris that has collected on top of the storm grate and in curbside rain gutters. Please note: If you notice a major blockage or issue with a storm drain, contact your local municipality immediately.
  2. Use a scrub brush or toilet bowl scrubber to remove debris that may be stuck to the storm grate.
  3. Adopt a storm drain(s) and maintain a regular cleaning schedule: Make a note on your calendar each quarter to clean and clear debris from storm drains nearby your home or workplace. And, make a habit of checking your storm drains after rainstorms when clogging is most common.
  4. Host a community clean-up day that includes trash pick-up, storm drain cleaning, and disseminating information on the impacts of stormwater runoff and what we can do to help.
  5. Consider contacting your local watershed association or municipality about getting drain markers installed on storm drains throughout the community. The markers act as a continued public reminder that anything dumped into a storm drain eventually ends up in our precious waterways downstream.

Remember: Small actions lead to big achievements in protecting water quality. 

Fall Events Spotlight: Conferences, Symposiums, & Fundraisers

This fall, Princeton Hydro is participating in a variety of events, including presenting at conferences that explore topics ranging from floodplain management to stream restoration to stormwater management. Here’s a snapshot of what’s to come:

OCTOBER 3: GREAT SWAMP GALA & SILENT AUCTION

The Great Swamp Watershed Association, a nonprofit organization dedicated to protecting and improving the water resources of the Passaic River region, is hosting its 2019 Gala & Silent Auction. This year’s event is being held in honor of Congresswoman Mikie Sherrill for her commitment to protecting our planet and growing the clean energy economy in New Jersey. The evening will include a cocktail hour, dinner banquet, and expansive silent auction.

LEARN MORE & REGISTER

 

OCTOBER 4: 46th ANNUAL ANJEC ENVIRONMENTAL CONGRESS

The Association of New Jersey Environmental Commissions (ANJEC) is a nonprofit organization that’s been supporting efforts to protect the environment and preserve natural resources in communities throughout New Jersey for 50 years. The Environmental Congress is an annual statewide gathering of environmental commissions, local officials, agencies, citizen groups and environmental organizations, which includes an exhibitors hall, farmer’s market, and workshops on a variety of current environmental topics. Princeton Hydro, a business member of the ANJEC, will be exhibiting during the event. Come say “hello” to our staff at the booth: Vice President Mark Gallagher, Senior Project Manager Kelly Klein, Communications Strategist Dana Patterson, and Marketing Coordinator Kelsey Mattison.

LEARN MORE & REGISTER

 

OCTOBER 9: SOCIETY FOR AMERICAN MILITARY ENGINEERS (SAME) MEGA MARYLAND SMALL BUSINESS CONFERENCE

The conference, being held in Baltimore, gives small and minority businesses in the architecture, engineering and construction industries the opportunity to come together with federal agencies in order to showcase best practices and highlight future opportunities to work in the federal market. Nearly 500 professionals throughout the Mid-Atlantic region are expected to attend this year’s MEGA Maryland, which includes 25+ speakers and 50+ exhibits. Be sure to stop by the Princeton Hydro booth!

LEARN MORE & REGISTER

 

OCTOBER 15 – 17: NEW JERSEY ASSOCIATION FOR FLOODPLAIN MANAGEMENT (NJAFM) 15TH ANNUAL CONFERENCE

NJAFM is hosting its 15th Annual Conference and Exhibition in Atlantic City, NJ. Participants will attend meetings and seminars covering topics, including hazard mitigation, flood insurance, flood modeling, stormwater management, construction standards and more. Princeton Hydro’s Christiana Pollack, GISP, CFM is giving a presentation about the Blue Acres ecological restoration project, which increases storm resiliency by reducing flooding and stormwater runoff by improving the ecological and floodplain function within the former residential properties acquired by the NJDEP Blue Acres Program. This presentation will highlight the green infrastructure techniques employed including restoration of native coastal forest and meadow.

LEARN MORE & REGISTER

 

OCTOBER 16 – 17: 7TH ANNUAL DELAWARE RIVER WATERSHED FORUM

The 7th Annual Delaware River Watershed Forum, taking place in Allentown, PA, brings together organizations and individuals spanning the four watershed states of PA, NY, NJ, and DE. The Forum allows for collaboration among those working on environmental conservation and policy; and provides professional and personal development opportunities. Workshops will focus on topics such as water quality, community engagement, equity, and environmental policy. Princeton Hydro President Geoff Goll, P.E., Senior Project Manager Kelly Klein, and Communications Strategist Dana Patterson are participating in this year’s event. Geoff and Kelly, along with Alan Hunt of the Musconetcong Watershed Association, are leading a “Musconetcong River Restoration Tour” on Oct 16.

Learn More & Register

 

OCTOBER 16 – 17: VILLANOVA STORMWATER MANAGEMENT SYMPOSIUM

The theme of this year’s Villanova University College of Engineering Stormwater Management Symposium is “Building Resilience into Stormwater.” Participants will attend technical sessions, hear a variety of presentations, and have an opportunity to take part in field trips and networking events. Topics covered during the symposium include Water Reuse and Harvesting, Stormwater Regulations and Design, Vegetated Infiltration Systems and more. Princeton Hydro is thrilled to be attending!

Learn More & Register

 

OCTOBER 17: Deal Lake Commission Environmental Education Public Meeting

The Deal Lake Commission (DLC) is hosting an informational gathering for which members of the public are invited to learn about environmental topics related to the lake and surrounding watershed.  At 6:30pm, Princeton Hydro founder Dr. Stephen Souza along with Jeannie Toher, DLC Commissioner, are giving a presentation on stormwater management and green infrastructure. The goal of this workshop session is to demonstrate the types of things that we can all do on a local scale to better control stormwater runoff and reduce nutrient loading, the primary causes of the lake’s water quality challenges.  Following the workshop, stay for the DLC’s monthly meeting and learn what else is going on with the management, restoration and maintenance of Deal Lake.

Learn More

 

OCTOBER 26: THE NATURE CONSERVANCY IN NJ’S OAK LEAF AUCTION

We are a proud sponsor of the Nature Conservancy’s Oak Leaf Auction being held at The Ridge in Basking Ridge, NJ. Participants of this fun fundraising event will enjoy live and silent auctions for items like artwork, weekend getaways, one-of-a-kind experiences, and much more. The evening also includes cocktails, appetizers and networking opportunities.

Learn More About The Nature Conservancy

 

NOVEMBER 1: NEW JERSEY WATERSHED CONFERENCE

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, a proud sponsor of the event, is exhibiting and giving two presentations: Director of Aquatic Programs Dr. Fred Lubnow is presenting on “An Overview of the Causes and Impacts of Harmful Algal Blooms.” Marketing Coordinator Kelsey Mattison is leading a workshop on “Flipping the Script on American Environmental Thought.”

Learn more & Register

 

NOVEMBER 1: NY-NJ HARBOR ESTUARY PROGRAM’S 2019 ANNUAL CONFERENCE

Are you a natural resource manager, scientist, conservation advocate, or policy leader? Join the NY-NJ Harbor & Estuary Program and the Hudson River Foundation for the 2019 Restoration Conference. The conference, titled “Explore Lessons Learned for a Changing Future at HEP,” will explore how habitat restoration can shape our community’s response to a changing climate. The day will feature a series of plenary presentations and interactive workshops that will help participants better understand these challenges, current initiatives, and the state of practice and scientific understanding.

Learn more & Register

 

NOVEMBER 7 – 9: ENGINEERS WITHOUT BORDERS NATIONAL CONFERENCE

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, is hosting its National Conference in Pittsburgh, PA. Staff Engineer Natalie Rodrigues, EIT, CPESC-IT is an active volunteer with EWB. Natalie began volunteering for the organization seven 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. The conference includes dynamic discussions with industry leaders, educational opportunities about complex global challenges that engineers can solve, and networking with the people driving the engineering sector’s socially minded future.

Learn more & Register

 

NOVEMBER 14: SOCIETY FOR AMERICAN MILITARY ENGINEERS (SAME) PHILADELPHIA RESILIENCY SYMPOSIUM

SAME Philadelphia is hosting a one-day symposium featuring experts on infrastructure resiliency in the face of extreme storms, flooding and other natural disasters. Presentation topics include, Coastal Resiliency, Public/Private Partnerships for Resiliency, and Climate Vulnerability and Adaptation/Flood Risk.  Stop by the Princeton Hydro exhibitor booth to say hello to Princeton Hydro President Geoffrey Goll, P.E. and Marketing Coordinator Kelsey Mattison. We hope to see you there!

LEARN MORE & REGISTER

 

NOVEMBER 11 – 15: NORTH AMERICAN LAKE MANAGEMENT SOCIETY (NALMS) CONFERENCE

NALMS‘ 39th International Symposium, being held in Burlington, VT, is themed “Watershed Moments: Harnessing Data, Science, and Local Knowledge to Protect Lakes.” This year’s symposium includes a robust exhibit hall, a variety of field trips, and a wide array of presentations on topics ranging from water level management to combating invasive species to nutrient pollution and more. Dr. Fred Lubnow will be presenting a poster on Harmful Algal Blooms in Lake Hopatcong, and Dr. Stephen Souza, a founding principal of Princeton Hydro, is leading a workshop on Stormwater Management for Lake Managers, which is designed to demonstrate the importance of implementing ecologically appropriate, cost-effective green infrastructure stormwater management techniques as part of comprehensive lake restoration plan. In addition to conference activities, visitors will enjoy Vermont’s scenic beauty and a wide variety of outdoor recreational opportunities.

Learn more & Register

 

NOVEMBER 18 – 20: MID-ATLANTIC STREAM RESTORATION CONFERENCE

Mid-Atlantic Stream Restoration Conference, hosted by the Resource Institute, invites resource professionals, researchers and practitioners to participate in discussions and workshops focused on Building Resilient Streams in the Mid-Atlantic and Northeast regions. Princeton Hydro is giving two presentations during the conference:

  • Columbia Lake Dam Removal; Using Drones for Quantitative Evaluation of River Restoration by Geoffrey Goll, P.E., Princeton Hydro President; Casey Schrading, EIT, Staff Engineer; and Beth Styler-Barry of The Nature Conservancy.
  • Innovative Design and Funding Approaches for Dam Removal Projects Where an Unfunded Mandate Exists by Geoffrey Goll, P.E.; Princeton Hydro President; Kirk Mantay, PWS, GreenTrust Alliance; John Roche, Maryland Department of Environment; and Brett Berkley, GreenVest.
Learn more & Register

 

NOVEMBER 20 – 22: 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’s Chief Operating Officer Kevin M. Yezdimer, PE and Communication Strategist Dana Patterson are attending the 2019 SAME SBC Conference, which is being held in Dallas, Texas. The program consists of networking events, small business exhibits, a variety of speakers and much more.

LEARN MORE & REGISTER

 

STAY TUNED FOR MORE EVENT SPOTLIGHTS!

Dr. Fred Lubnow of Princeton Hydro Featured in Magazine Article on Chautauqua Lake

The U.S. is home to thousands of lakes both natural and manmade. Lakes are incredibly important features in the landscape that provide numerous beneficial services, including domestic water supply, hydro-electric power, agricultural water supply, recreation, and tourism. They also provide essential habitat for fish, wildlife and aquatic organisms.

Lakes are complex and dynamic systems, each situated in a unique landscape context. Maintaining the ecological health of a lake is no easy feat. A lot goes on behind the scenes to maintain water quality and a balanced lake ecosystem. Successful, long-term lake management requires a proactive approach that addresses the causes of its water quality problems rather than simply reacting to weed and algae growth and other symptoms of eutrophication.

Chautauqua Magazine recently published an article about the science behind the management of Chautauqua Lake, which features our Director of Aquatic Programs Dr. Fred Lubnow. We’ve included an excerpt below. Click here to view the full article and photos:

Dr. Fred Lubnow is a scientist and director of aquatic programs at Princeton Hydro, a consulting organization based in Exton, Pennsylvania, that is often called on to support lake and watershed regions that want to develop a long-term plan for lake conservation.

He says that while his firm focuses on the development of data and intelligence to inform decision making in regard to freshwater ecosystems, his work is really about coalition building.

“As a scientist and a consultant, you learn over time that you are building a coalition stakeholders and determining what we can agree on to help everyone in the community,” Lubnow said.

Ten years ago, Princeton Hydro was hired to do some stream and inlet monitoring for various stakeholders at Chautauqua Lake. More recently, they’ve been contracted to conduct third-party monitoring of the impacts of the Spring 2019 herbicide applications in the south basin of Chautauqua Lake…

Continue reading!

 

Princeton Hydro is the industry leader in lake restoration and watershed management. We have conducted diagnostic studies and have developed management and restoration plans for over 300 lakes and watersheds throughout the country. This has included work for public and private recreational lakes, major water supply reservoir, and watershed management initiatives conducted as part of USEPA and/or state funded programs. For more information about our lake management services, go here: http://bit.ly/pondlake.