Setting the Precedent: Blue Acres Floodplain Restoration in Linden

The City of Linden, located 13 miles southwest of Manhattan in Union County, New Jersey, is a highly urbanized area with a complex mix of residential, commercial, and industrial land uses. Originally settled as farmland on broad marshes, the City has deep roots in industrial production that emerged in the 19th century, and its easily accessible location on the Arthur Kill tidal straight helped fuel this industrial development.

Now, the City of Linden, which is home to more than 40,000 people, is considered a transportation hub: it has three major highways running through it (the New Jersey Turnpike, Route 1, and Route 27); its rail station provides critical commuter and industry access; the Linden Municipal Airport is a gateway to the NY/NJ metropolitan area; and its access point on the Arthur Kill is used by shipping traffic to the Port Authority of NY and NJ.

Unfortunately, the industrial boom left a legacy of pollution in the city, so much, that the Tremley Point Alliance submited an official Envionmental Justice Petition to the state. In 2005, the New Jersey Environmental Task Force selected the community for the development of an Environmental Justice Action Plan and listed it as one of six environmental justice communites in New Jersey.

As do many urban municipalities, Linden suffers severe flooding from heavy rains and storms. One of the significant sources of flood water threatening the City comes from stormwater runoff.

Like other communities in the Arthur Kill Watershed, Linden also suffers severe flooding from heavy rains and storms with one of the significant sources of flood water coming from stormwater runoff. Due to a high percentage of impervious cover from houses, roadways, and sidewalks, even small rain events generate a significant amount of stormwater runoff. Over time, these conditions have been exacerbated by the historic loss of coastal wetlands and outdated infrastructure. Nuisance flooding is especially problematic as runoff cannot drain from the area at a sufficient rate to prevent flooding during normal or elevated tidal conditions. Very simply, heavy rainfall is one factor contributing to recurring flooding.

In 2012, Hurricane Sandy caused wide-spread destruction throughout New Jersey and the entire eastern seaboard. The City of Linden was hard hit, and the City’s Tremley Point neighborhood was especially storm-ravaged. Tremley Point, a low-lying community of about 275 homes located at the headwaters of Marshes Creek and in the 100-year floodplain of the Rahway River, is regularly flooded during normal rain events. During Hurricane Sandy, local news outlets reported that a 15-foot tidal surge overtook Tremley Point homes, destroyed roads, and washed up hazardous material such as a 150-gallon diesel tank.

To help communities like Tremley Point recover, the New Jersey Department of Environmental Protection (NJDEP) launched the Blue Acres program under which NJDEP purchases homes from willing sellers at pre-Sandy market values, so residents in areas of repetitive and catastrophic flooding can rebuild their lives outside flood-prone areas. Structures are demolished and the properties are permanently preserved as open space for recreation or conservation purposes. The program began in 1995 and expanded with federal funding after Sandy. The goal of the Blue Acres Program is to dramatically reduce the risk of future catastrophic flood damage and to help families to move out of harm’s way.

As part of the NJDEP Blue Acres Program, Princeton Hydro, in collaboration with the City of Linden, Rutgers University, NJDEP, Phillips 66, National Fish and Wildlife Foundation, New Jersey Corporate Wetlands Restoration Partnership, and Enviroscapes, has undertaken one of the first ecological restoration projects within Blue Acres-acquired properties, which are located in the Tremley Point neighborhood. This project 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.

The City of Linden Blue Acres restoration project 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.

The project includes the development and implementation of an on-the-ground green infrastructure-focused floodplain enhancement design involving the restoration of native coastal floodplain forest and meadow, as well as floodplain wetlands. The restored area provides natural buffering to storm surge and enhances floodplain functions to capture, infiltrate, store, and slow excess stormwater to reduce the risk of future flood damage. In addition, it restores natural habitat and provides public recreation access on NJDEP Blue Acres property.

The design includes re-planting the parcels and the installation of a walking path through part of the area. It also includes the creation of a floodplain bench for the adjacent drainage ditch, an unnamed tributary to Marshes Creek. A floodplain bench is a low-lying area adjacent to a stream or river constructed to allow for regular flooding in these areas. Site improvements include grading of the floodplain bench and minor depressional area; 6-12-inches of tilling, soil amendment, and planting within the planting area; and construction of the gravel pathway.

The project will result in valuable environmental and community benefits to the area, including an annual reduction in stormwater runoff of 4.1 million gallons. This represents a 45% reduction in stormwater runoff. Restoration of the floodplain will also help reduce community vulnerability to storms. The hope is that this project will be a model that fosters more floodplain restoration projects in the future.

For more information on the Blue Acres Program, please visit the DEP website.

2019 Successes: A Year in Review

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

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

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

Hudson River Bear Mountain Bridge (Photo from Wikipedia)

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

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

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

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

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

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

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

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

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

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

7. Princeton Hydro Earned Three Prestigious Awards.

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

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

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

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

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

10. New Year, New Locations!

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

 

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

Feasibility Study Identifies Key Opportunities for Hudson River Habitat Restoration

Hudson River Bear Mountain Bridge (Photo from Wikipedia)

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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A Day in the Life of a Construction Oversight Engineer

Have you ever wondered what it actually means to conduct construction oversight on a project? Our engineers regularly do so to ensure design plans are being implemented correctly. But, construction oversight requires a lot more than just the ability to oversee. Our engineers have to understand the ins and outs of the plans, be adaptable, fast-thinking, and incredibly capable of communicating with and coordinating various parties.

Let’s walk through a day in the life of one of our construction oversight engineers, Casey Schrading, EIT, and outline the key components of his job:

SAFETY. When it comes to construction sites, safety always comes first. It is important to have the proper health and safety training before entering an active construction zone. On an active construction site, there could be many different hazards that workers encounter. Before heading to the site, Casey makes sure he has all his necessary safety equipment and protection gear. Personal Protection Equipment (PPE) usually includes a neon safety vest (visibility), hard hat (head protection), long pants (protective clothing), safety glasses (eye protection), and steel-toed boots (foot protection). In some cases, on construction sites with more risk factors, higher levels of PPE may be required including hearing protection, gloves, respiratory masks, fall protection equipment, and disposable Tyvek coveralls.

COORDINATION.  For most construction projects, the day starts early. Upon arrival, Casey checks the site out to see if anything has changed from the day before and takes pictures of the site. He then checks in with the contractor to discuss the plan for the day and any outstanding items from the day prior.

Most of the day consists of a back and forth process between watching the construction workers implement the design and then monitoring and checking the design plans. In order for the contractor to properly implement the design, the oversight engineer must direct the workers during the installation process; for many designs, there are critical angles, locations, heights, and widths that features must be installed at. It is imperative for the oversight engineer to direct and work hand-in-hand with the contractor so those features are installed correctly for effective design implementation.

ON-SITE MONITORING.  For certain projects, the day-to-day construction oversight tasks may get a little more involved. For instance, when conducting construction oversight for our Columbia Dam Removal project, Casey was tasked with taking turbidity samples every three hours at two locations along the Paulins Kill — one upstream of the site to collect baseline data and one downstream of the site to quantify the site’s effect on turbidity. If the turbidity readings downstream of the site came out too high, Casey would then have to determine how those high levels were affecting the turbidity in the Delaware River, which the Paulins Kill discharges into less than a quarter mile downstream of the site. If flooding in the Delaware River wasn’t enough to pose safety concerns, Casey would then take readings at two additional locations upstream and downstream of the Delaware River-Paulins Kill confluence. Again, the upstream reading served as a baseline reading for turbidity while the downstream reading showed the effects of the Paulins Kill on the Delaware River.

These turbidity samples were necessary because this project involved passive sediment transport, meaning the sediment that had built up behind the dam for over a century was going to slowly work its way downstream as the dam was notched out piece by piece, as opposed to it being dredged out before the barrier removal. It’s important to monitor turbidity in a case like this to make sure levels remain stable. The need for monitoring at construction sites further emphasizes the need for construction oversight engineers to be multifaceted.

ADAPTATION.  In all construction projects, the goal is to have everything installed or constructed according to plan, but, with so many environmental factors at play, that rarely happens. Because of the ever-changing nature of most of our projects, it is essential that our construction oversight engineers have the keen ability to adapt and to do so quickly. Casey has experienced a range of changes in plan while conducting construction oversight. He says the skills he relies on most is communication. When something changes, it’s imperative that the onsite engineer knows exactly who to contact to work out a solution. Sometimes that might be Princeton Hydro’s internal project manager, or sometimes it might be a regulatory official from NJDEP.

WEEKLY MEETINGS.  Another critical part of construction oversight is facilitating weekly coordination meetings. The weekly meeting is usually attended by the contractor, the engineering firm, and the client.  The parties will discuss what has happened thus far at the site and what still needs to happen, allowing them to establish action items. Occasionally, other entities like organizations that provided funding for a project or regulatory agencies, will also be involved in those conversations. The weekly meetings are designed to keep everybody on task and help to ensure every party’s goals and needs are being met.

DOCUMENTATION.  Anytime field work is being conducted, it is essential to document the happenings and the progress made. This documentation usually comes in the form of a Daily Field Report (DFR). A DFR includes information about the work performed on a given day, such as measurements, quantities of structures installed, and how that installation process went. Also included in the DFRs are clear and descriptive photographs.

COMMUNICATION.  Working on any project, it’s important to make sure all involved parties understand the reason behind each installation. It is often easier for a construction team to implement plans correctly if they know and understand why each part of it is important and included in the project. Explaining why a task needs to be completed also helps relieve tension that could potentially arise between the engineer and the contractor. It is essential to make sure every person on the project team is on the same page.

PUBLIC OUTREACH.  Another critical aspect of construction oversight is having the ability to successfully communicate with the public. Members of the community surrounding a site need to be kept apprised of the goings on so they can remain safe during the construction period and understand the goals of the project. When citizens understand the purpose and goals of a project, they are more likely to support and respect it.

REGULATORY COMPLIANCE.  Understanding the permitting surrounding a project is also essential to success as a construction oversight engineer. The engineer has to understand the ins and outs of the permitting and regulations in order to be able to make decisions about changes in the plan and to be able to successfully point the contractor in the correct and compliant direction.

Construction oversight is a tedious and incredibly important job, yet I really enjoy it because it gives me a new and better understanding of the engineering design process,” explains Casey. He feels it gives him a much more practical understanding of engineering design, as he has seen what kinds of plans are actually implementable and what that process looks like. “Watching a design plan get implemented brings the project full circle and allows me to take that knowledge and experience back to the office and back into the design process.

Princeton Hydro provides construction oversight services to private, public, and nonprofit clients for a variety of ecosystem restoration, water resource, and geotechnical projects across the Northeast.  Learn more.

Casey graduated from Virginia Tech in 2018 with a degree in Biological Systems Engineering and now works as a staff engineer for the firm with a focus in water resources engineering. He has experience in ecological restoration, flood management, water quality analysis, and best management practices. His experience also includes construction oversight for dam removal and restoration projects as well as design, technical writing, and drafting for a wide variety of water resources engineering projects. In his free time Casey very much enjoys travelling, hiking, skiing, and camping.

If you enjoyed this blog, check out another one from our “Day in the Life” series, and stay tuned for more:

A Day in the Life of a Stormwater Inspector

A Day in the Life of a Stormwater Inspector

Walking through a park isn’t always a walk in the park when it comes to conducting stormwater inspections. Our team routinely spots issues in need of attention when inspecting stormwater infrastructure; that’s why inspections are so important.

Princeton Hydro has been conducting stormwater infrastructure inspections for a variety of municipalities in the Mid-Atlantic region for a decade, including the City of Philadelphia. We are in our seventh year of inspections and assessments of stormwater management practices (SMPs) for the Philadelphia Water Department. These SMPs are constructed on both public and private properties throughout the city and our inspections focus on areas served by combined sewers. 

Our water resource engineers are responsible for construction oversight, erosion and sediment control, stormwater facilities maintenance inspections, and overall inspection of various types of stormwater infrastructure installation (also known as “Best Management Practices” or BMPs).

The throat of a sinkhole observed by one of our engineers while on site.

Our knowledgeable team members inspect various sites regularly, and for some municipalities, we perform inspections on a weekly basis. Here’s a glimpse into what a day of stormwater inspection looks like:

The inspector starts by making sure they have all their necessary safety equipment and protection. For the purposes of a simple stormwater inspection the Personal Protection Equipment (PPE) required includes a neon safety vest, hard hat, eye protection, long pants, and boots. Depending on the type of inspection, our team may also have to add additional safety gear such as work gloves or ear plugs. It is recommended that inspectors hold CPR/First Aid and OSHA 10 Hour Construction Safety training certificates. 

Once they have their gear, our inspection team heads to the site and makes contact with the site superintendent. It’s important to let the superintendent know they’re there so that 1) they aren’t wondering why a random person is perusing their construction site, and 2) in case of an emergency, the superintendent needs to be aware of every person present on the site.

Once they arrive, our team starts by walking the perimeter of the inspection site, making sure that no sediment is leaving the project area. The team is well-versed in the standards of agencies such as the Pennsylvania Department of Environmental Protection, the Pennsylvania Department of Transportation, the New Jersey Department of Environmental Protection, and local County Soil Conservation Districts, among others. These standards and regulations dictate which practices are and are not compliant on the construction site.

After walking the perimeter, the inspection team moves inward, taking notes and photos throughout the walk. They take a detailed look at the infrastructure that has been installed since the last time they inspected, making sure it was correctly installed according to the engineering plans (also called site plans or drainage and utility plans). They also check to see how many inlets were built, how many feet of stormwater pipe were installed, etc.

If something doesn’t look quite right or needs amending, our staff makes recommendations to the municipality regarding BMPs/SMPs and provides suggestions for implementation.

One example of an issue spotted at one of the sites was a stormwater inlet consistently being inundated by sediment. The inlet is directly connected o the subsurface infiltration basin. When sediment falls through the inlet, it goes into the subsurface infiltration bed, which percolates directly into the groundwater. This sediment is extremely difficult to clean out of the subsurface bed, and once it is in the bed, it breaks down and becomes silt, hindering the function of the stormwater basin.

To remedy this issue, our inspection team suggested they install stone around the perimeter of the inlet on three sides. Although this wasn’t in the original plan, the stones will help to catch sediment before entering the inlet, greatly reducing the threat of basin failure.

Once they’ve thoroughly inspected the site, our team debriefs the site superintendent with their findings. They inform the municipality of any issues they found, any inconsistencies with the construction plans, and recommendations on how to alleviate problems. The inspector will also prepare a Daily Field Report, summarizing the findings of the day, supplemented with photos.

In order to conduct these inspections, one must have a keen eye and extensive stormwater background knowledge. Not only do they need to know and understand the engineering behind these infrastructure implementations, they need to also be intimately familiar with the laws and regulations governing them. Without these routine inspections, mistakes in the construction and maintenance of essential stormwater infrastructure would go unnoticed. Even the smallest overlook can have dangerous effects, which is why our inspections team works diligently to make sure that will not happen.

Our team conducts inspections for municipalities and private entities throughout the Northeast. Visit our website to learn more about our engineering and stormwater management services.

 

Senior Engineer Kevin Yezdimer Appointed to Chief Operating Officer

We are thrilled to announce a new executive position in the firm, Chief Operating Officer (COO), to which Kevin M. Yezdimer, P.E. was appointed effective July 1, 2019. Most recently, Kevin served as the Director of Geoscience Engineering and Office Manager for the company’s Sicklerville, New Jersey location since joining the firm in 2016.

Princeton Hydro has grown from a small four person idea operating out of a living room to a 65+ person qualified Small Business with five office locations in the Northeast region. Last year, the firm realized record revenue and is projected to continue notable growth due to its strong position in the marketplace of providing innovative and “value-added” ecological and engineering solutions. With Princeton Hydro’s steady growth, this new executive position is essential to optimize operational processes across the firm’s technical practice areas and geographic locations, as well as to best implement their strategic growth plan within the Mid-Atlantic and New England regions.

We are all excited and happy to have Kevin join the Princeton Hydro Executive Team. He has demonstrated leadership and success in executing strategies that are key to our success. Kevin has proven himself to have an intuitive understanding of technical and business practices, and can communicate these often complicated issues into meaningful and comprehensible conversation. Most importantly, Kevin is a true mentor to staff and will be able to support them in his new role,” said Princeton Hydro’s President Geoffrey Goll, P.E.I am proud that we were able to internally find someone to fill this position, and am confident that Kevin will be a great fit. As a firm, we are committed to maintaining the mission and values envisioned by the firm’s founders, including supporting our diverse clientele in the commercial, NGO, and government industries, while maintaining a personal touch and small business culture. This new position is vital to maintaining the stability and continuity of our mission and values.

Kevin is a multidisciplinary professional civil engineer with degrees in both Geology and Civil Engineering. With 14 years of experience as a design consultant and project manager, Kevin has proven his ability to lead others. His move to COO is a testament to all of Kevin’s continued success. In his new role, he will be working hand-in-hand with each practice area, the administration, and the principals to propel the firm forward. He will also work to ensure that the company culture remains driven towards excellence in innovative and integrated science and engineering. As the company continues to grow and mature, Kevin will ensure that the firm remains well-balanced and provide a positive working culture for all employees.

Our firm’s executives have afforded me with a tremendous leadership opportunity; I am truly humbled, honored, and ready to take on the role of Chief Operating Officer for Princeton Hydro,” said Kevin Yezdimer, P.E. “In this new position, I will have the ability to empower our passionate staff to achieve their full potential, unify operational practices, and assure that our business goals and mission are achieved. I’m looking forward to further implementing the vision of the firm’s founders as we continue to grow and evolve.

Kevin resides in Hockessin, Delaware with his wife Kristen, three children, and newly rescued dog Lizzy. Outside of the office, you can find Kevin running, swimming, playing disc golf, performing home improvement projects, following all Philadelphia sports (especially the Eagles), developing his faith, and striving to make the most of each and every day.