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)

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:

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. 

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. 

REGISTER: Green Infrastructure Stormwater Management One-Day Course

REGISTRATION IS STILL OPEN FOR MONTCLAIR STATE UNIVERSITY’S GREEN INFRASTRUCTURE STORMWATER MANAGEMENT ONE-DAY CONTINUING EDUCATION COURSE BEING HELD ON SEPTEMBER 20, 2019 FROM 8 AM – 4 PM

Are you a consultant, planner, municipal representative, community leader, or project manager seeking to learn more about Green Stormwater Infrastructure & Management Techniques? This one-day course is for YOU!

Green infrastructure techniques have increasingly become the “go to” strategy to address flooding, water quality, and environmental impacts caused by stormwater runoff. Whether it be rain gardens or regional bioretention basins, infiltration basins or other large-scale bio engineered BMPs, green infrastructure is being implemented everywhere from suburban subdivisions to urban redevelopment sites. Unfortunately, while growing popular, these techniques are often misapplied, improperly constructed, or inadequately maintained.

This innovative one-day class focuses on the proper design and implementation of green infrastructure BMPs, as well as their special maintenance requirements. The course curriculum includes interactive presentations, case studies and project examples.

This year’s course will cover the following topics and more:

  • The Application and Advantages of Green Infrastructure Stormwater Management Techniques
  • Design and Construction of Infiltration Basins
  • Data Collection Needs: Soil, Geotechnical, and Groundwater Hydrology Data
    Design and Construction of Gravel Wetland Systems
  • Rain Garden Design and Application
  • Green Infrastructure Stormwater Options and Alternative Capping Techniques for Remediation Sites

Dr. Stephen Souza, Princeton Hydro Co-Founder and President of Clean Waters Consulting, LLC, is the faculty coordinator for the course, which also features a lecture by Princeton Hydro’s Green Infrastructure Practice Area Leader Dr. Clay Emerson, PE, CFM.

Course participants will also receive professional credits, including:

  • New Jersey LSRP CECs: 7 Technical CECs (NJ SRPLB Course # 2015-065);
  • New Jersey Professional Engineers: 7 CPCs;
  • New Jersey Board of Architects: 7 hours of CECs;
  • Certified Floodplain Managers: 6.5 CECs; and
  • NJ Public Health Continuing Education Contact Hours: 7 CEs.

Princeton Hydro is proud to partner with Montclair State University and take part in this valuable continuing professional education course. We hope to see you there!

Learn More & Register Today

Enjoy Your Labor Day Nature Adventures Responsibly

Seven Tips for Environmentally-Friendly Outdoor Fun

Labor Day is right around the corner! Many people will soon be packing up the car with fishing gear and heading to their favorite lake for a fun-filled weekend.

As biologists, ecologists, environmentalists, and outdoor enthusiasts, all of us at Princeton Hydro fully enjoy getting outside and having fun in nature. We also take our responsibility to care for and respect our natural surroundings very seriously. We play hard and work hard to protect our natural resources for generations to come.

These seven tips will help you enjoy your Labor Day fishing, boating, and outdoor adventures with minimal environmental impact:

  • Before you go, know your local fishing regulations. These laws protect fish and other aquatic species to ensure that the joys of fishing can be shared by everyone well into the future.

  • Reduce the spread of invasive species by thoroughly washing your gear and watercraft before and after your trip. Invasives come in many forms – plants, fungi, and animals – and even those of microscopic size can cause major damage.

  • Stay on designated paths to avoid disrupting sensitive and protected areas, like wetlands, shorelines, stream banks, and meadows. Disturbing and damaging these sensitive areas can jeopardize the health of the many important species living there.

  • Exercise catch and release best practices. Always keep the health of the fish at the forefront of your activities by using the right gear and employing proper techniques. Get that info by clicking here.

  • Use artificial lures or bait that is native to the area you’re fishing in. Live bait that is non-native can introduce invasive species to water sources and cause serious damage to the surrounding environment.

  • Plan ahead and map your trip. Contact the office of land management to learn about permit requirements, area closures and other restrictions. Use this interactive map to find great fishing spots in your area, the fish species you can expect to find at each spot, nearby gear shops, and more!

Armed with these seven tips, you can now enjoy your weekend while feeling rest assured that you’re doing your part to protect the outdoor spaces and wild places we all love to recreate in! Go here to learn about some of the work Princeton Hydro does to restore and protect our natural resources.

120903 Dock
“Respect nature and it will provide you with abundance.”

–compassionkindness.com

Managing Urban Stormwater Runoff and Revitalizing Natural Habitat at Harveys Lake

Measuring 630+ acres, Harveys Lake, located in Luzerne County, Pennsylvania, just northeast of Wilkes-Barre, is the largest natural lake (by volume) within the Commonwealth of Pennsylvania, and is one of the most heavily used lakes in the area. It is classified as a high quality – cold water fishery habitat (HQ-CWF) and is designated for protection under the classification.

Since 2002, The Borough of Harveys Lake and the Harveys Lake Environmental Advisory Council  has worked with Princeton Hydro on a variety of lake management efforts focused around maintaining high water quality conditions, strengthening stream banks and shorelines, and managing stormwater runoff.

Successful, sustainable lake management requires identifying and correcting the cause of eutrophication as opposed to simply reacting to the symptoms of eutrophication (algae and weed growth). As such, we collect and analyze data to identify the problem sources and use these scientific findings to develop a customized management plan that includes a combination of biological, mechanical, and source control solutions. Here are some examples of the lake management strategies we’ve utilized for Harveys Lake:

 

Floating Wetland Islands

Floating Wetland Islands (FWIs) are an effective alternative to large, watershed-based natural wetlands. Often described as self-sustaining, FWIs provide numerous ecological benefits. They assimilate and remove excess nutrients, like nitrate and phosphorous, that could fuel algae growth; provide habitat for fish and other aquatic organisms; help mitigate wave and wind erosion impacts; and provide an aesthetic element. FWIs are also highly adaptable and can be sized, configured, and planted to fit the needs of nearly any lake, pond, or reservoir.

Five floating wetland islands were installed in Harveys Lake to assimilate and reduce nutrients already in the lake. The islands were placed in areas with high concentrations of nutrients, placed 50 feet from the shoreline and tethered in place with steel cables and anchored. A 250-square-foot FWI is estimated to remove up to 10 pounds of nutrients per year, which is significant when it comes to algae.

Princeton Hydro worked with the Harveys Lake Environmental Advisory Council and the Borough of Harveys Lake to obtain funding for the FWIs through the Pennsylvania Department of Environmental Protection (PADEP).

 

Streambank & Shoreline Stabilization

Harveys Creek

The shoreline habitat of Harveys Lake is minimal and unusual in that a paved road encompasses the lake along the shore with most of the homes and cottages located across the roadway, opposite the lake. In addition to the lake being located in a highly populated area, the limited shoreline area adds to the challenges created by urban stormwater runoff.

Runoff from urban lands and erosion of streambanks and shorelines delivers nutrients and sediment to Harveys Lake. High nutrient levels in the lake contribute to algal blooms and other water quality issues. In order to address these challenges, the project team implemented a number of small-scale streambank and inlet stabilization projects with big impacts.

The work included the stabilization of the streambank downstream for Harveys Lake dam and along Harveys Creek, the design and installation of a riparian buffer immediately along the lake’s shoreline, and selective dredging to remove sediment build up in critical areas throughout the watershed.

 

Invasive Species Management

Hydrilla (Hydrilla verticillata), an aggressively growing aquatic plant, took root in the lake in 2014 and quickly infected 250 acres of the lake in a matter of three years. If left untreated, hydrilla will grow to the water’s surface and create a thick green mat, which prevents sunlight from reaching native plants, fish and other organisms below. The lack of sunlight chokes out all aquatic life.

In order to prevent hydrilla from spreading any further, Princeton Hydro and SePRO conducted an emergency treatment of the impacted area utilizing the systemic herbicide Sonar® (Fluridone), a clay-based herbicide. SonarOne, manufactured by SePRO, blocks hydrilla’s ability to produce chloroplasts, which in turn halts the photosynthetic process. The low-concentration herbicide does not harm fish, wildlife or people using the lake. Surveys conducted after the treatment showed it was working – the hydrilla had turned white and was dying off. Additional Sonar treatments followed and efforts to eradicate hydrilla in the lake continue.

Dr. Fred Lubnow, our Director of Aquatic Programs, estimates complete eradication of the aquatic plant could take around five years. Everyone can do their part in preventing the spread of this and other invasive species. Boaters and lake users must be vigilant and remove all vegetation from the bottom of watercrafts and trailers.

 

Stormwater Best Management Practices (BMPs)

In 2009, Princeton Hydro developed a stormwater implementation plan (SIP) for Harveys Lake. The goal of the stormwater/watershed-based efforts was to reduce the lake’s existing annual total phosphorus load to be in full compliance with the established Total Maximum Daily Load (TMDL). This TMDL is related to watershed-based pollutant loads from total phosphorus (TP) and total suspended solids (TSS), which can contribute to algal blooms.

A number of structural urban runoff projects were implemented throughout the watershed. This includes the design and construction of two natural stream channel projects restoring 500 linear feet of tributaries and reducing the sediment and nutrient loads entering the lake. A series of 38 urban runoff BMPs, including nutrient separating devices and roadside infiltration, were installed in areas immediately adjacent to the lake to further reduce the loads of nutrients and other pollutants reaching the lake.

The photos below show a stormwater project that was completed in the Hemlock Gardens Section of the Watershed. Hemlock Gardens is a 28-acre section of land located in the southeastern portion of the watershed. It contains approximately 26 homes, has very steep slopes, unpaved dirt roads, and previously had no stormwater infrastructure in place.

Two structural stormwater BMPs were installed:

  • A nutrient separating baffle box, which utilizes a three-chamber basin with screens to collect leaf litter, grass clippings and trash
  • A water polishing unit that provides a platform for secondary runoff treatment

In 1994, Harveys Lake was identified as “impaired” by PADEP due to large algal blooms. In 2014, Harveys Lake was removed from the list of impaired waters. Project partners attribute the recovery of this lake to the stream restoration, urban runoff BMP implementation, and the use of in-lake nutrient reduction strategies.

The Harveys Lake Watershed Protection Plan Implementation Project proved that despite the lake being located in an urbanized watershed, it is possible to implement cost-effective green infrastructure and stormwater retrofit solutions capable of significantly decreasing pollutant loading to the lake.

To learn more about our lake and pond management services or schedule a consultation, visit: http://bit.ly/pondlake.

Four Ways Climate Change Can Affect Your Lake

The Local Effects of Climate Change Observed Through our Community Lakes

Climate change is an enormous concept that can be hard to wrap your head around. It comes in the form of melting ice caps, stronger storms, and more extreme seasonal temperatures (IPCC, 2018). If you’re an avid angler, photographer, swimmer, boater, or nature enthusiast, it’s likely that because of climate change you’ll bear witness to astonishing shifts in nature throughout the greater portion of your lifetime. This is especially true with respect to lakes.

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Lakes are living laboratories through which we can observe the local effects of climate change in our own communities. Lake ecosystems are defined by a combination of various abiotic and biotic factors. Changes in hydrology, water chemistry, biology, or physical properties of a lake can have cascading consequences that may rapidly alter the overall properties of a lake and surrounding ecosystem. Most of the time the results are negative and the impacts severe.

“Managing loads of phosphorous in watersheds is even more important as the East Coast becomes increasingly warmer and wetter thanks to climate change,” said Dr. Fred Lubnow, Director of Aquatics in a recent NJ.com interview. “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.”

Recognizing and monitoring the changes that are taking place locally brings the problems of climate change closer to home, which can help raise awareness and inspire environmentally-minded action.

We put together a list of four inter-related, climate change induced environmental impacts that can affect lakes and lake communities:

1. Higher Temperatures = Shifts in Flora and Fauna Populations

The survival of many lake organisms is dependent on the existence of set temperature ranges and ample oxygen levels. The amount of dissolved oxygen (DO) present in a lake is a result of oxygen diffusion from the atmosphere and its production by algae and aquatic plants via photosynthesis. An inverse relationship exists between water temperature and DO concentrations. Due to the physical properties of water, warmer water holds less DO than cooler water.

This is not good news for many flora and fauna, such as fish that can only survive and reproduce in waters of specific temperatures and DO levels. Lower oxygen levels can reduce their ability to feed, spawn and survive. Populations of cold water fish, such as brown trout and salmon, will be jeopardized by climate change (Kernan, 2015).

358-001-carp-from-churchvilleAlso, consider the effects of changing DO levels on fish that can tolerate these challenging conditions. They will thrive where others struggle, taking advantage of their superior fitness by expanding their area of colonization, increasing population size, and/or becoming a more dominant species in the ecosystem. A big fish in a little pond, you might say. Carp is a common example of a thermo-tolerant fish that can quickly colonize and dominate a lake’s fishery, in the process causing tremendous ecological impact (Kernan, 2010).

2. Less Water Availability = Increased Salinity

Just as fish and other aquatic organisms require specific ranges of temperature and dissolved oxygen to exist, they must also live in waters of specific salinity. Droughts are occurring worldwide in greater frequency and intensity. The lack of rain reduces inflow and higher temperatures promote increased evaporation. Diminishing inflow and dropping lake levels are affecting some lakes by concentrating dissolved minerals and increasing their salinity.

Studies of zooplankton, crustaceans and benthic insects have provided evidence of the consequences of elevated salinity levels on organismal health, reproduction and mortality (Hall and Burns, 2002; Herbst, 2013; Schallenberg et al., 2003). While salinity is not directly related to the fitness or survival rate of all aquatic organisms, an increase in salinity does tend to be stressful for many.

3. Nutrient Concentrations = Increased Frequency of Harmful Algal Blooms

Phosphorus is a major nutrient in determining lake health. Too little phosphorus can restrict biological growth, whereas an excess can promote unbounded proliferation of algae and aquatic plants.

before_strawbridgelake2If lake or pond water becomes anoxic at the sediment-water interface (meaning the water has very low or completely zero DO), phosphorus will be released from the sediment. Also some invasive plant species can actually “pump” phosphorus from the sediments and release this excess into the water column (termed luxurious uptake). This internally released and recycled sedimentary phosphorus can greatly influence lake productivity and increase the frequency, magnitude and duration of algae blooms. Rising water temperatures, declining DO and the proliferation of invasive plants are all outcomes of climate change and can lead to increases in a lake’s phosphorus concentrations and the subsequent growth and development of algae and aquatic plants.

Rising water temperatures significantly facilitate and support the development of cyanobacteria (bluegreen algae) blooms. These blooms are also fueled by increasing internal and external phosphorus loading. At very high densities, cyanobacteria may attain harmful algae bloom (HAB) proportions. Elevated concentrations of cyanotoxins may then be produced, and these compounds seriously impact the health of humans, pets and livestock.

rain-garden-imagePhosphorus loading in our local waterways also comes from nonpoint sources, especially stormwater runoff. Climate change is recognized to increase the frequency and magnitude of storm events. Larger storms intensify the mobilization and transport of pollutants from the watershed’s surrounding lakes, thus leading to an increase in nonpoint source loading. Additionally, larger storms cause erosion and instability of streams, again adding to the influx of more phosphorus to our lakes. Shifts in our regular behaviors with regards to fertilizer usage, gardening practices and community clean-ups, as well as the implementation of green infrastructure stormwater management measures can help decrease storm-related phosphorus loading and lessen the occurrence of HABs.

4. Cumulative Effects = Invasive Species

A lake ecosystem stressed by agents such as disturbance or eutrophication can be even more susceptible to invasive species colonization, a concept coined “invasibility” (Kernan, 2015).

For example, imagine that cold water fish species A has experienced a 50% population decrease as a result of warming water temperatures over ten years. Consequently, the fish’s main prey, species B, has also undergone rapid changes in its population structure. Inversely, it has boomed without its major predator to keep it in check. Following this pattern, the next species level down – species B’s prey, species C – has decreased in population due to intense predation by species B, and so on. Although the ecosystem can potentially achieve equilibrium, it remains in a very unstable and ecologically stressful state for a prolonged period of time. This leads to major changes in the biotic assemblage of the lake and trickle-down changes that affect its recreational use, water quality and aesthetics.

• • •

Although your favorite lake may not experience all or some of these challenges, it is crucial to be aware of the many ways that climate change impacts the Earth. We can’t foresee exactly how much will change, but we can prepare ourselves to adapt to and aid our planet. How to start? Get directly involved in the management of your lake and pond. Decrease nutrient loading and conserve water. Act locally, but think globally. Get out and spread enthusiasm for appreciating and protecting lake ecosystems. Also, check out these tips for improving your lake’s water quality.


References

  1. IPCC. “Summary for Policymakers. “Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty.” World Meteorological Organization, Geneva, Switzerland, 32 pp. 2018.
  2. Hall, Catherine J., and Carolyn W. Burns. “Mortality and Growth Responses of Daphnia Carinata to Increases in Temperature and Salinity.” Freshwater Biology 47.3 (2002): 451-58. Wiley. Web. 17 Oct. 2016.
  3. Herbst, David B. “Defining Salinity Limits on the Survival and Growth of Benthic Insects for the Conservation Management of Saline Walker Lake, Nevada, USA.” Journal of Insect Conservation 17.5 (2013): 877-83. 23 Apr. 2013. Web. 17 Oct. 2016.
  4. Kernan, M. “Climate Change and the Impact of Invasive Species on Aquatic Ecosystems.” Aquatic Ecosystem Health & Management (2015): 321-33. Taylor & Francis Online. Web. 17 Oct. 2016.
  5. Kernan, M. R., R. W. Battarbee, and Brian Moss. “Interaction of Climate Change and Eutrophication.” Climate Change Impacts on Freshwater Ecosystems. 1st ed. Chichester, West Sussex, UK: Wiley-Blackwell, 2010. 119-51. ResearchGate. Web. 17 Oct. 2016.
  6. Schallenberg, Marc, Catherine J. Hall, and Carolyn W. Burns. “Consequences of Climate-induced Salinity Increases on Zooplankton Abundance and Diversity in Coastal Lakes”Marine Ecology Progress Series 251 (2003): 181-89. Inter-Research Science Center. Inter-Research. Web.