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When New Jersey Manufacturers Insurance Group
(NJM) developed their new Regional Operations Facility, a 55-acre corporate campus in Hammonton, New Jersey, they approached the construction with one major goal at the forefront: stormwater management.

Fundamental to that goal was designing a green infrastructure stormwater management system capable of containing on site nearly all the stormwater runoff generated by storm events up to and including a 100-year frequency, 24-hour duration storm.

The group hired Princeton Hydro, recognized as a leader in innovative, cost-effective, and environmentally sound stormwater management, to develop a concept plan that could be built within the context of proper stormwater management and meet the stringent requirements of the NJ Pinelands Comprehensive Management Plan.

To accomplish the ambitious stormwater management goals, the project team designed and implemented an integrated stormwater management system that combined traditional and green infrastructure components, and consisted of bioinfiltration basins, parking lot islands, a wetland basin, and a bioretention island. These features were designed to promote the interception, evapotranspiration, and infiltration of stormwater runoff at its source.

Emphasis was given to green infrastructure BMPs specifically capable of treating and infiltrating large volumes of runoff. Thus, all of the infiltration areas were designed using a soil amendment process where the underlying soils were excavated and amended with organic material to improve the underlying recharge capabilities of the soils. To complement the BMPs, the team designed and installed 120,000 gallon below-grade rainwater capture and reuse system. The system captures roof runoff to be used for on-site irrigation, which not only reduces stormwater volume but also decreases the facility’s water usage.

The project is one of the first projects in New Jersey built to infiltrate nearly 100% of the on-site runoff and uses site-design-based stormwater capacity to determine allowable impervious cover.

[gallery link="none" ids="11591,11590,11592"]

Before construction began, the team implemented a comprehensive study, which began with a detailed analysis of the site’s soils, with particular attention given to physical properties of the soil and the depth to seasonal high water (groundwater). During construction, Princeton Hydro provided monitoring services for all earthwork activities. Our team was on site full-time during critical activities to ensure that the project was built in accordance with the intent of the original design and ensure the maintenance of the project schedule. The team also provided environmental and geotechnical design and engineering services throughout the corporate campus construction, including the analysis of subsurface structures shop drawings and providing consultation support to the general contractor.

For the project, we partnered with Burgis Associates, Inc. who created site designs, provided landscape architectural and professional planning services, and helped to obtain agency approvals. The landscape program sought to establish native plant communities that filter runoff, provide an aesthetically pleasing visual, reduce invasive species, create habitat for pollinators and other critical species, and require limited maintenance to stay healthy and flourishing.

Post construction, the Princeton Hydro team led the preparation of the scope of services, budget, and proposal for the Stormwater Basin Maintenance, which included mowing and clearing the vegetation in nine infiltration basins. The basins were inspected monthly for functionality and for the presence of invasive plants. And, we are happy to report that the basins are all working properly and invasive plants have been eradicated.

At Princeton Hydro, we are experts in stormwater management; we recognize the numerous benefits of green infrastructure; and we’ve been incorporating green infrastructure into our engineering designs since before the term was regularly used in the stormwater lexicon. Click below to read about a Stormwater Treatment Train we designed and implemented in Thompson Park, a 675-acre recreation area in Middlesex County, New Jersey.

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The New Jersey Department of Environmental Protection (NJDEP) launched a Youth Inclusion Initiative to help the State of New Jersey develop the next generation of environmental protection, conservation and stewardship leaders while also providing an avenue for young adults from open space-constrained communities to engage with nature as they provide valuable stewardship services to the public through jobs at NJDEP. 

This year, the youth inclusion program is partnering with Groundwork Elizabeth, Rutgers University Camden, and Newark’s Ironbound Community Corporation to create a workforce development curriculum for people ages 17 to 24. Groundwork Elizabeth sent 12 participants to this year’s program, and Rutgers Camden and the Ironbound Community Corporation each sent 10.

[caption id="attachment_11299" align="aligncenter" width="771"] Photo by NJDEP[/caption]

The curriculum provides career education in the environmental protection field and helps the young participants develop the skills necessary to pursue those career paths in New Jersey. Participants learn through classroom instruction and by working across sectors regulated by the NJDEP, including water resources, air quality, energy and sustainability, public lands management, and wildlife. 

Susan Lockwood of NJDEP’s Division of Land Resource Protection’s Mitigation Unit reached out to Princeton Hydro to showcase ecosystem restoration and mitigation efforts across the state as well as discuss the variety of career roles that make these projects possible. Our portion of the curriculum entailed each group of students visiting two sites to learn about the benefits of restoring a landscape with native vegetation. Our discussion explored different fields of work related to urban environmental restoration and water resource protection and the job responsibilities of environmental scientists, water resource engineers, geologists, ecologists, pesticide applicators, and regulatory compliance specialists. 

The Abbott Marshlands in Trenton, New Jersey

[gallery link="none" ids="11287,11288,11281"]

After a quick stop at NJDEP’s office in Trenton to learn about NJ invasive species, all three groups popped over to the Tulpehaking Nature Center in Mercer County’s John A. Roebling Park to see the restoration site in the Abbott Marshlands. The 3,000-acre Abbott Marshlands is the northernmost freshwater tidal marsh on the Delaware River and contains valuable habitat for many rare species like River Otter, American Eel, Bald Eagle, and various species of wading birds. Unfortunately, the area has experienced a significant amount of loss and degradation, partially due to the introduction of the invasive Common Reed (Phragmites australis). For Mercer County Park Commission, Princeton Hydro implemented a restoration plan to remove Common Reed and expose the native seed bank in 40-acres of the marsh to increase biodiversity, improve recreational opportunities, and enhance visitor experience. Students learned how to tell the difference between the invasive Common Reed vs. native Wild Rice (Zizania palustris L.). They utilized tools of the trade like field guides and binoculars to identify flora and fauna in the marsh. Learn more about this project.


Mullica River Wetland Mitigation Site in Evesham, New Jersey

[gallery link="none" ids="11343,11342,11282"]

After visiting the Roebling site, students from Camden traveled down to Evesham Township in Burlington County to visit the Mullica River Wetland Mitigation Site. For this project, Princeton Hydro worked with GreenVest, LLC to restore a highly degraded 34-acre parcel of land which was previously used for cranberry cultivation. Through the implementation of restoration activities focused on removing the site’s agricultural infrastructure, Princeton Hydro and GreenVest were able to restore a natural wetland system on the site and over 1,600 linear feet of stream, providing forested, scrub-shrub, and emergent wetlands, forested uplands, headwater stream and riparian buffer, and critical wildlife habitat. The project also significantly uplifted threatened and endangered species habitats including Timber Rattlesnake.

Susan Lockwood of NJDEP, Owen McEnroe of GreenVest, and Dana Patterson of Princeton Hydro, lead the group of 10 students. They learned the difference between restoration and mitigation and got to experience the remoteness of Pinelands habitat. Walking through the site, we shared how the dam and dike removal helped to restore the river back to its natural free-flowing state and the numerous resulting environmental benefits.The site was chosen for the Camden students in order to demonstrate that successful mitigation and restoration projects happen throughout the State and not far from urban centers like Camden. Learn more about this project.


3. Third River Floodplain Wetland Enhancement Project in Bloomfield, New Jersey

[gallery link="none" ids="11344,11279,11277"]

After visiting the Roebling site, students from Newark and Elizabeth trekked up to Essex County to visit an urban wetland creation project now known as Lion Gate Park. The once densely developed, abandoned Scientific Glass Factory in Bloomfield Township was transformed into a thriving public park with 4.2 acres of wetlands. Students heard the story of how this project came to be; decades of advocacy and litigation by community members and environmental nonprofits to stop redevelopment of the site into 148 townhomes. Bloomfield Township eventually secured the property to preserve as open space through a range of grants from NJDEP. Serving as the ecological engineer to Bloomfield Township, Princeton Hydro designed, permitted, and oversaw construction for the restoration project and is currently monitoring the site. The restoration work brought back to the land valuable ecological functions and natural floodplain connection, enhanced aquatic and wildlife habitat, and increased flood storage capacity for urban stormwater runoff. Learn more about this project.


 

The NJDEP Youth Inclusion Initiative began on July 5 with a week of orientation classes, and continued through August with classroom and in-field learning. The initiative culminates on August 26 with a graduation and NJDEP Career Day, during which students will have the opportunity to meet with and discuss career options with various organizations tabling at the event, including Princeton Hydro.

Click here to learn more about the NJDEP education program. If you’re interested in learning more about Princeton Hydro’s ecological restoration services, click here.

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In October 2021, the largest stream restoration in Maryland was completed. Over 7 miles (41,000 linear feet) of Tinkers Creek and its tributaries were stabilized and restored.

The project was designed by Princeton Hydro for GV-Petro, a partnership between GreenVest and Petro Design Build Group. Working with Prince George’s County Department of the Environment and coordinating with the Maryland-National Capital Parks and Planning Commission, this full-delivery project was designed to meet the County’s Watershed Implementation Plan total maximum daily load (TMDL) requirements and its National Pollutant Discharge Elimination System Municipal Separate Storm Sewer System (MS4) Discharge Permit conditions.

Today, we are thrilled to report that the once highly urbanized watershed is flourishing and teeming with life:

[gallery columns="2" size="medium" link="none" ids="10632,10631"]

We used nature-based design and bioengineering techniques like riparian zone planting and live staking to prevent erosion and restore wildlife habitat.

[gallery columns="2" size="medium" ids="10635,10634"]

10,985 native trees and shrubs were planted in the riparian area, and 10,910 trees were planted as live stakes along the streambank.

[gallery columns="2" size="medium" ids="10637,10636"]

For more information about the project visit GreenVest's website and check out our blog:

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Thousands of native flowering plants and grasses were planted at Thompson Park in Middlesex County, New Jersey. Once established, the native plant meadow will not only look beautiful, it will reduce stormwater runoff and increase habitat for birds, pollinators, and other critical species.

The planting was completed by community volunteers along with Eric Gehring of  Kramer+Marks Architects, Middlesex County Youth Conservation Corps, Rutgers Cooperative Extension of Middlesex County, South Jersey Resource Conservation and Development Council, and Princeton Hydro Landscape Architect Cory Speroff, PLA, ASLA, CBLP. 

All of the plants that were installed are native to the north-central region of New Jersey. Volunteers planted switchgrass (panicum virgatum), orange coneflower (rudbeckia fulgida), blue wild indigo (baptisia australis), partridge pea (chamaecrista fasciculata), Virginia mountain mint (pycnanhemum virginianum), and aromatic aster (symphyotrichum oblongifolium). In selecting the location for each of the plants, special consideration was given to each species' drought tolerance and sunlight and shade requirements. The selected plant species all provide important wildlife value, including providing food and shelter for migratory birds.

Photos provided by: Michele Bakacs

The planting initiative is one part of a multi-faceted Stormwater Treatment Train project recently completed in Thompson Park. The project is funded by a Water Quality Restoration 319(h) grant awarded to South Jersey Resource Conservation and Development Council by the NJDEP.

Middlesex County Office of Parks and Recreation and Office of Planning, NJDEP, South Jersey Resource Conservation and Development Council, Middlesex County Mosquito Extermination Commission, Freehold Soil Conservation District, Rutgers Cooperative Extension, Enviroscapes, and Princeton Hydro worked together to bring this project to fruition.

To learn more about the Thompson Park Zoo stormwater project, check out our recent blog:

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What is Stormwater Runoff?

Stormwater runoff is all of the rainfall or snowmelt water that is not absorbed into the ground and instead flows over land. When not managed properly, stormwater runoff causes issues like pollution in our waterways, flooding, and erosion. Stormwater runoff has been cited in multiple studies as a leading cause of water quality impairment to our local lakes and rivers. And, with increasing levels of rainfall from climate change impacts, stormwater management is an especially critical issue for communities all across the U.S.  

What is Stormwater Management?

Stormwater management focuses on reducing runoff and improving water quality through a variety of techniques. 

Traditional stormwater management methods include things like storm drains, retention ponds, and culverts. Green stormwater infrastructure uses vegetation, soil, and other natural components to manage stormwater. Green stormwater infrastructure systems mimic natural hydrology to take advantage of interception, evapotranspiration, and infiltration of stormwater runoff at its source. Examples include rain gardens, constructed wetlands, vegetated bioswales, and living shorelines.  Many stormwater systems include a combination of grey and green infrastructure management practices. 

Stormwater management treatment "trains" combine multiple stormwater management processes in order to prevent pollution and decrease stormwater flow volumes that negatively affect the receiving waterbody.

Let’s Take a Look at a Stormwater Treatment Train in Action

The Thompson Park Zoo in New Jersey

Thompson Park is a 675-acre recreation area - the largest developed park in the Middlesex County park system - with numerous attractions including playgrounds, ballfields, hiking trails, and a zoo. The zoo is an animal haven that houses over 50 geese and fowl, goats, and approximately 90 deer in a fenced enclosure. The park also features Lake Manalapan. 

Within the zoo is a 0.25-acre pond that impounds stormwater runoff from adjacent uplands and two stormwater-fed tributaries to Lake Manalapan and Manalapan Brook. There are three tributaries to the pond  with varying levels of erosion. The western tributary contains a headcut that is approximately four feet high. A headcut is created by a sudden down-cutting of the stream bottom. Similar to a miniature waterfall, a headcut slowly migrates upstream and becomes deeper as it progresses. The headcut in the Zoo tributary had destabilized the stream by eroding and incising its channel and banks. Additionally, foraging by Zoo inhabitants had removed most ground cover around the pond and associated tributaries, which also caused erosion. 

The bare soil conditions, headcut, and manure from the Zoo animals were contributing sediment, nutrient, and pathogen loading to the Zoo pond and subsequently Lake Manalapan. The Zoo pond drains to an outlet structure, a 24-inch reinforced concrete pipe (RCP), and subsequently to a vegetated swale via a stormwater outlet. A second outlet pipe drains stormwater runoff from an asphalt parking lot which discharges to the vegetated swale. 

The shoreline of Lake Manalapan where the vegetated swale drains into the lake was the subject of a previous restoration project during which a diverse suite of native plants was installed; however, the swale was not included in this project and a maintained lawn, which does not adequately filter stormwater runoff or provide any ecosystem services. The swale also had little access to its floodplain where vegetation can help filter non-point source (NPS) pollutants from the Zoo pond and adjacent uplands.

Implementing a Stormwater Management Treatment Train

In order to increase channel stability, decrease erosion, improve water quality and ecological function, and reduce the NPS pollutants originating from the Zoo, a stormwater management treatment train was designed and constructed. 

Middlesex County Office of Parks and Recreation and Office of Planning, the New Jersey Department of Environmental Protection (NJDEP), South Jersey Resource Conservation and Development Council (SJRC&D), Middlesex County Mosquito Extermination Commission, Freehold Soil Conservation District, Rutgers Cooperative Extension, Enviroscapes and Princeton Hydro worked together to fund,  design, permit,  and construct the following stormwater management measures: 

  • stabilizing the western tributary to Lake Manalapan and its existing headcut by constructing a rock step-pool sequence; 
  • installing BioChar filter bags within the Zoo pond to remove excess nutrients from the water column and bed sediments; 
  • daylighting a portion of the existing 24-inch RCP in order to widen the stream channel and allow for more stormwater absorption 
  • grading the vegetated swale to provide positive drainage and reduce mosquito breeding habitat; 
  • grading a floodplain bench adjacent to the swale to allow for increased water storage and absorption times and thus greater nutrient removal; 
  • installing outlet protection measures to reduce stormwater velocity and prevent scour within the swale; and 
  • replacing the manicured grass with native vegetation within transition areas to reduce erosion potential and increase biodiversity.

To see the project elements taking shape and being completed, watch our video:

https://www.youtube.com/watch?v=qXqDjH8knDY

The project is funded by a Water Quality Restoration 319(h) grant awarded to SJRC&D by the NJDEP for continued implementation of watershed-based measures to reduce NPS pollutant loading and compliance with a total phosphorus (TP) Total Maximum Daily Load (TMDL) established by the NJDEP for Lake Manalapan. The TMDL is a regulatory term in the U.S. Clean Water Act, that identifies the maximum amount of a pollutant (in this case phosphorus) that a waterbody can receive while still meeting water quality standards. 

“The South Jersey Resource Conservation and Development Council was pleased to participate in this project. Partnering with these various governmental agencies and private entities to implement on the ground conservation and water quality improvements aligns perfectly with our mission.  We are thrilled with the great work done at Thompson Park and look forward to continuing this partnership.”

Craig McGee, South Jersey Resource Conservation and Development Council District Manager

Construction of the stormwater treatment train components began in early August 2021 and was completed by the end of September 2021. 

The first step of the stormwater treatment train was to stabilize the tributary to Lake Manalapan and its associated headcut. Streambank stabilization measures included grade modifications to create a gradual stream slope and dynamically stable form with improved habitat features, including riffles and pools, with gravel and cobble substrate. On August 17, grading of the floodplain bench began, the RCP was exposed, and the team started  excavation for the lower three steps in the step-pool sequence.

On August 20, the rock grade and step-pool sequence were completed. And, fabric was installed along both sides of the rock-lined channel to increase stream-bank stability. Rock was placed within the pools to cover the edge of the fabric. We are very pleased to report that the newly restored channel held up to two large storm events during the construction process.

Bags of BioChar, a pure carbon charcoal-like substance made from organic material, were installed across the Zoo pond using an anchor and line system. The BioChar bags help to remove TP and other nutrients from the water column and bed sediments of the Zoo pond and subsequently Manalapan Brook Watershed. The team also built, planted and installed a floating wetland island, an effective green infrastructure solution that improves water quality by assimilating and removing excess nutrients that could fuel algae growth.

After conclusion of pipe lighting, excavation of the floodplain bench and installation of scour protection, native perennial vegetation was planted within the floodplain and swale in order to provide sediment deposition and nutrient uptake functions, as well as aquatic food web services and water temperature moderation before flows are discharged to Lake Manalapan. The plantings also enhance and create suitable avian and pollinator species habitat, and greater flora and fauna diversity.


This stormwater treatment train project improves the habitat and water quality of the Manalapan Brook Watershed by addressing NPS pollutants that originate from Thompson Park Zoo. The completed work also supports the Watershed Protection and Restoration Plan for the Manalapan Brook Watershed by reducing TSS and TP loads in compliance with the TMDL. Additionally, the project improves the overall ecosystem by stabilizing eroded streambanks, installing native and biodiverse vegetation, and reducing the quantity of pollutants entering Lake Manalapan. 

“Thompson Park Zoo is an excellent model for showcasing a successful and comprehensive approach to stormwater management and watershed restoration through a dynamic multi-stakeholder partnership. We are so proud to be a part of this project and continue to support the Manalapan Brook Watershed Protection Plan through a variety of restoration activities.”

Amy McNamara, E.I.T, Princeton Hydro Project Manager and Water Resource Engineer

At Princeton Hydro, we are experts in stormwater management; we recognize the numerous benefits of green infrastructure; and we’ve been incorporating green infrastructure into our engineering designs since before the term was regularly used in the stormwater lexicon. Click here to learn more about our stormwater management services.

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Just 50 miles southeast of New York City, tucked between two municipalities, sits a 650+ acre tidal salt marsh which spans the shorelines of the South River in densely populated, highly developed Central New Jersey. The South River is the first major tributary of the Raritan River, located 8.3 miles upstream of the Raritan River’s mouth, which drains into Raritan Bay.

The Lower Raritan River and Raritan Bay make up a large part of the core of the NY-NJ Harbor and Estuary Program. Within the Raritan Estuary, the South River wetland ecosystem is one of the largest remaining wetland complexes. While the South River salt marsh ecosystem has been spared from direct development, it has been degraded in quality, and does not provide optimal habitat for wildlife or maximum flood protection for residents. This area is subject to fairly regular tidal flooding (particularly when it occurs simultaneously with a storm) and periodic—generally more severe—flooding during more significant events such as nor’easters and tropical storms. Hurricanes Irene and Sandy caused damage in the Boroughs of Sayreville and South River too.

In 2018, Princeton Hydro and Rutgers University, along with the Lower Raritan Watershed Partnership, Middlesex County, Borough of Sayreville, Borough of South River, NY/NJ Baykeeper, Raritan Riverkeeper, and the Sustainable Raritan River Initiative, secured funding from NFWF’s National Coastal Resilience Fund for the “South River Ecosystem Restoration & Flood Resiliency Enhancement Project.”

The South River Ecosystem Restoration and Flood Resiliency Enhancement Project aims to:

  • Reduce socioeconomic damages to the Boroughs of South River and Sayreville caused by storm damage, flooding, and sea level rise;

  • Transform degraded wetlands to high-quality marsh that can reduce flooding and enhance fish & wildlife habitat; and

  • Engage stakeholders in activities about coastal resilience and ecological health to maximize public outreach in the Raritan River Watershed.

For this 165-acre tidal marsh and transitional forest “eco-park,” the project team is conducting an ecosystem restoration site assessment and design. This phase of the coastal restoration project will result in a permit-ready engineering design plan that stabilizes approximately 2.5 miles of shoreline, reduces flood risk for smaller coastal storms, and enhances breeding and foraging habitat for 10 state-listed threatened and endangered avian species.

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Project Area History

This area has experienced repeated flooding, especially during large storms. For example, coastal areas of Sayreville and South River flooded after Hurricane Floyd (1999), Tropical Storm Ernesto (2006), Hurricane Irene (2011), and Hurricane Sandy (2012). Over the last century, there have been several studies and assessments completed for the South River, many of which identify this project area as a priority location for flooding improvements. The following are key reports and studies published about the project area and surrounding communities:

  • NJ Legislature’s 71st Congress published a report, “Basinwide Water Resource Development Report on the Raritan River Basin” which focused on navigation and flood control for the entire Raritan River Basin. It discussed recommendations for flood control and local storm drainage, setting the stage for future actions.

1970s
  • NJDEP Division of Water Resources published Flood Hazard Reports for the Matchaponix Brook System and Raritan River Basin, which delineated the floodplains in the South River, and its tributaries, the Manalapan Brook and Matchaponix Brook.

1980s
  • USACE New York District released a “Survey Report for Flood Control, Raritan River Basin,” which served as a comprehensive study of the Raritan River Basin and recommended several additional studies. Although the South River was studied, none of the proposed improvements were determined to be economically feasible at that time.

  • Project area was listed as one of the Nation’s Estuaries of National Significance.

1990s
  • USACE conducted a multi-purpose study of this area. This preliminary investigation identified Federal interest in Hurricane and Storm Damage Reduction and ecosystem restoration along the South River and concluded that a 100-year level of structural protection would be technically and economically feasible.

2000s
  • USACE NYD and NJDEP released a joint draft, “Integrated Feasibility Report and Environmental Impact Statement” for the South River, Raritan River Basin, which focused on “Hurricane & Storm Damage Reduction and Ecosystem Restoration.” Because it was previously determined that there were no widespread flooding problems upstream, the study area was modified to focus on the flood-prone areas within the Boroughs of Sayreville and South River, as well as Old Bridge Township.

Towards a More Resilient South River Ecosystem

Through collaboration with our project partners and following input provided from a virtual stakeholder meeting held in December 2020, Princeton Hydro developed a conceptual design for an eco-park that incorporates habitat enhancement and restoration, and protective measures to reduce impacts from flooding while maximizing public access and utility. Public access includes trails for walking and designated areas for fishing. The eco-park can also be used for additional recreation activities such as bird watching and kayaking.

Highlights of the conceptual design include the following features:

  • Approximately two miles of trails with overlook areas, connection to fishing access, and a kayak launch.

  • ~3,000 linear feet of living shoreline, located along portions of the Washington Canal and the South River, to provide protection from erosion, reduce the wake and wave action, and provide habitat for aquatic and terrestrial organisms.

  • ~60 acres of enhanced upland forest to provide contiguous habitat areas for resident and migratory fauna.

  • A tidal channel that will connect to the existing mud flat on the southeastern part of the site and provide tidal flushing to proposed low and high marsh habitats along its banks.

  • A vegetated berm with a trail atop will extend the length of the site to help mitigate flood risk.

  • Two nesting platforms for Osprey, a species listed as “Threatened” in NJ

  • Designated nesting habitat for the Diamondback Terrapin, a species listed as “Special Concern” in NJ

Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of ecological rehabilitation and floodplain management projects. Click here to read about a coastal rehabilitation and resiliency project we completed in New Jersey.

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UPDATE: THIS PROJECT WAS SUCCESSFULLY COMPLETED IN OCTOBER 2021.

Just east of Washington D.C. in Prince George’s County, what will soon be the largest stream restoration in Maryland, is well underway. In this highly urbanized watershed, over 7 miles (41,000 linear feet) of Tinkers Creek and its tributaries, Meetinghouse Branch and Paynes Branch, will be stabilized and restored using nature-based design techniques.

The project was designed by Princeton Hydro for GV-Petro, a partnership between GreenVest and Petro Design Build Group. The project aims to prevent erosion and restore wildlife habitat using bioengineering techniques like riparian zone planting and live staking. 10,985 native trees and shrubs will be planted in the riparian area, and 10,910 trees will be planted as live stakes along the streambank. Recently, this project was expanded to include the stabilization and restoration of stormwater outfalls and headwater tributaries.

Working with Prince George’s County Department of the Environment and coordinating with the Maryland-National Capital Parks and Planning Commission, this full-delivery project is designed to meet the County’s Watershed Implementation Plan (WIP) total maximum daily load (TMDL) requirements and its National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Discharge Permit conditions.

[caption id="attachment_7741" align="aligncenter" width="936"] This photo, taken during a site visit in January 2021, documents the Tinkers Creek Stream Restoration progress[/caption]  

Prince George’s County borders the eastern portion of Washington, D.C and is the second-most populous county in Maryland. Tinkers Creek is located on a five-mile stretch of stream valley, from Old Branch Avenue to Temple Hills Road, in Clinton and Temple Hills, Maryland. The tributary system of Tinkers Creek is described as "flashy," meaning there is a quick rise in stream level due to rainfall as a result of its high proportion of directly connected urbanized impervious areas. Its streams have storm flow rates many times higher than that from the rural and forested sub-watersheds in the southeast.

[caption id="attachment_7890" align="aligncenter" width="360"] Unstable stormwater outlet in the Tinkers Creek Restoration area (before).[/caption]  

This stream restoration project was identified as a priority due to the significant levels of channel incision and the severity of erosion and its impacts on surrounding neighborhoods. Additionally, the project’s proximity to the headwater reaches located on Joint Base Andrews (JBA), so the ability to improve water quality and wildlife habitat made this project a high priority. It provides an important opportunity to create a safe, sustainable, and resilient stream valley in the community.

The design for the stream, and all of the tributaries within the restoration area, will restore these channels to their naturally-stable form. During the preliminary assessment of onsite conditions, the stream and tributaries within the restoration area were classified using geomorphic assessments and hydrologic and hydraulic analysis.

Once the stream types and conditions were identified, a series of restoration approaches were designed, including floodplain creation, bank stabilization using natural materials and plantings, re-aligning straightened stream channels to have a more natural sinuosity, stormwater conveyance, and natural material grade control structures. These changes will help to reduce channel flow velocities and shear stress for flows greater than bankfull; reduce bank erosion and maintain bank stability; treat and attenuate stormwater flows; stabilize outfalls and the receiving stream channels; and stabilize vertically unstable channels.

[caption id="attachment_7742" align="alignnone" width="1024"] Streambank stabilization measures in place, post construction (2019).[/caption]  

The project area contained various subsurface utilities like sanitary sewer along the entire reach and fiber-optics and natural gas lines crossing the corridor. Once constructed, the project will improve hydraulic, geomorphic, physicochemical, and biological stream functions. It will also increase floodplain connectivity, improve bedform diversity, restore riparian buffers, and protect public subsurface utilities. In addition to water quality benefits, this project will preserve and enhance the forested floodplain and provide ecological uplift throughout the entire stream corridor.

Planning and design for Tinkers Creek Stream Restoration began in early 2018 and construction is expected to finish ahead of schedule in Spring of 2022. Princeton Hydro is providing construction oversight of all critical structures, such as grade controls, headwater step-pool grade controls, bank stabilization structures, and stormwater outfalls.

The below photos, taken during a site visit in January, showcase some of the exciting progress made by the project team thus far.

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Stay tuned for more project updates!

Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of ecological rehabilitation projects. To learn more about our watershed restoration services, click here. We have partnered with GreenVest on a number of projects, including the award-winning Pin Oak Forest Conservation Area freshwater wetland restoration project and the Mattawoman Creek Mitigation Site wetland enhancement and restoration initiative. To learn more about GreenVest, click here.

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The Iowa Court and South Green Living Shoreline Project in Little Egg Harbor and Tuckerton, NJ, was awarded “Best Green Project” by Engineering News-Record magazine. The project is recognized for its use of innovative techniques to install new features to restore damage from Hurricane Sandy and protect the area from future storms.

In 2012, Superstorm Sandy devastated communities throughout New Jersey and the entire eastern seaboard. Storm resilience, flood mitigation, and shoreline restoration have since become top priorities for coastal communities and low-lying areas.

The Township of Little Egg Harbor, in conjunction with local partners including the Borough of Tuckerton, was the recipient of a $2.13 million Hurricane Sandy Coastal Resiliency Competitive Grant through the National Fish and Wildlife Foundation for a Marsh Restoration and Replenishment project. The grant was secured by New Jersey Future. The purpose of the project was to restore and replenish local marsh, wetlands, and beaches suffering extensive erosion along the shoreline.

T&M Associates, as the Municipal Engineer of Record for the project, oversaw all aspects of the design and implementation. T&M contracted Princeton Hydro to perform sediment sampling/testing and conduct hydrographic surveys, and Arthur Chew Consulting to assist with the feasibility study and design of the dredging project.

The project, which was completed in September 2019, provides long-term protection from erosion and will restore the vegetated shoreline habitats through strategic placement of plants, stone, sand fill, and other structural and organic materials. The living shoreline will help in the areas of storm protection, flood mitigation, and combatting shoreline erosion. The project was a great success for the Little Egg Harbor and Tuckerton communities.

[caption id="attachment_5584" align="aligncenter" width="899"]  [/caption]

Since the restoration of Iowa Court and South Green Street, this living shoreline model has received significant attention and praise, including in the American Council of Engineering Companies of New Jersey 2020 Engineering Excellence Awards; the New Jersey Society of Municipal Engineers 2019 Project of the Year Awards; and, now, this "Best Green Project" award from Engineering News-Record.

“There is growing interest in this approach from municipalities up and down the Jersey Shore. Storm and flood damage is still a pressing threat to hundreds of towns and boroughs, and it is widely accepted that storms like Sandy will only become more frequent due to the effects of climate change,” said Jason Worth, P.E., Group Manager at T&M Associates. “Thankfully, there is hope in innovation and creativity – with new approaches to living shorelines we can breathe life back into devastated beachfront communities and the natural ecosystems that support them.”

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

[caption id="attachment_5585" align="aligncenter" width="1016"]  [/caption]

[post_title] => Living Shoreline in Ocean County, NJ Voted "Best Green Project" [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => living-shoreline-ocean-county-new-jersey [to_ping] => [pinged] => [post_modified] => 2021-04-22 18:56:57 [post_modified_gmt] => 2021-04-22 18:56:57 [post_content_filtered] => [post_parent] => 0 [guid] => https://www.princetonhydro.com/blog/?p=5583 [menu_order] => 0 [post_type] => post [post_mime_type] => [comment_count] => 0 [filter] => raw ) [8] => WP_Post Object ( [ID] => 5431 [post_author] => 3 [post_date] => 2020-10-27 10:27:13 [post_date_gmt] => 2020-10-27 10:27:13 [post_content] =>

The Dunes at Shoal Harbor, a coastal residential community in Monmouth County, New Jersey, is situated adjacent to both the Raritan Bay and the New York City Ferry channel.  In July 2018, Princeton Hydro was contracted to restore this coastal community that was severely impacted by Hurricane Sandy. Today, we are thrilled to report that the shoreline protection design plans have been fully constructed and the project is complete.

Rendering of the shoreline protection design
September 2020
A rendering of the shoreline protection design by Princeton Hydro. A snapshot of Princeton Hydro's completed work in September 2020.

In order to protect the coastal community from flooding, a revetment had been constructed on the property many years ago. The revetment, however, was significantly undersized and completely failed during Hurricane Sandy. The community was subjected to direct wave attack and flooding, homes were damaged, beach access was impaired, and the existing site-wide stormwater management basin and outfall was completely destroyed.

July 2018
September 2020
Princeton Hydro performed a wave attack analysis commensurate with a category three hurricane event and used that data to complete a site design for shoreline protection. The site design and construction plans included:
  • The installation of a 15-foot rock revetment (one foot above the 100-year floodplain elevation) constructed with four-foot diameter boulders;

  • The replacement of a failed elevated timber walkway with a concrete slab-on-grade walkway, restoring portions of the existing bulkhead, clearing invasive plants, and the complete restoration of the failed stormwater basin and outlet; and

  • The development of natural barriers to reduce the impacts of storm surges and protect the coastal community, including planting stabilizing coastal vegetation to prevent erosion and installing fencing along the dune to facilitate natural dune growth.

These measures will prevent shoreline erosion, protect the community from wave attacks and flooding, and create a stable habitat for native and migratory species.

During the final walkthrough earlier this month, the Princeton Hydro team captured drone footage of the completed project site. Click below to watch the video:

For more images and background information on this project, check out the following photo gallery and read our original blog post from July 2018:

[gallery link="file" columns="4" ids="5447,5436,5450,5448,5446,5449,5445,5439"] [embed]https://www.princetonhydro.com/blog/dunes-at-shoal-harbor/[/embed]

For more information about Princeton Hydro’s engineering services, go here.

[post_title] => UPDATE: NJ's Dunes at Shoal Harbor Shoreline is Restored [post_excerpt] => [post_status] => publish [comment_status] => open [ping_status] => open [post_password] => [post_name] => dunes-at-shoal-harbor-update [to_ping] => [pinged] => [post_modified] => 2020-10-27 10:27:13 [post_modified_gmt] => 2020-10-27 10:27:13 [post_content_filtered] => [post_parent] => 0 [guid] => https://www.princetonhydro.com/blog/?p=5431 [menu_order] => 0 [post_type] => post [post_mime_type] => [comment_count] => 0 [filter] => raw ) [9] => WP_Post Object ( [ID] => 4727 [post_author] => 3 [post_date] => 2020-05-29 17:21:35 [post_date_gmt] => 2020-05-29 17:21:35 [post_content] => Photo from Eastwick Friends and Neighbors Coalition

Hydrology is the study of the properties, distribution, and effects of water on the Earth’s surface, in the soil and underlying rocks, and in the atmosphere. The hydrologic cycle includes all of the ways in which water cycles from land to the atmosphere and back. Hydrologists study natural water-related events such as drought, rainfall, stormwater runoff, and floods, as well as how to predict and manage such events. On the application side, hydrology provides basic laws, equations, algorithms, procedures, and modeling of these events.

Hydraulics is the study of the mechanical behavior of water in physical systems. In engineering terms, hydraulics is the analysis of how surface and subsurface waters move from one point to the next, such as calculating the depth of flow in a pipe or open channel. Hydraulic analysis is used to evaluate flow in rivers, streams, stormwater management networks, sewers, and much more.

Combined hydrologic and hydraulic data, tools, and models are used for analyzing the impacts that waterflow - precipitation, stormwater, floods, and severe storms - will have on the existing infrastructure. This information is also used to make future land-use decisions and improvements that will work within the constraints of the hydrologic cycle and won’t exacerbate flooding or cause water quality impairment.

Simply put, hydrologic and hydraulic modeling is an essential component of any effective flood risk management plan.

Putting Hydrologic & Hydraulic Analysis to Work in Philadelphia

Eastwick, a low-lying urbanized neighborhood in Southwest Philadelphia, is located in the Schuylkill River Watershed and is almost completely surrounded by water: The Cobbs and Darby creeks to the west, the Delaware River and wetlands to the south, and the Schuylkill River and Mingo Creek to the east. The community is at continual risk of both riverine and coastal flooding, and faces an uncertain future due to sea level rise and riverine flooding exacerbated by climate change.

Princeton Hydro, along with project partners KeystoneConservation and University of Pennsylvania, conducted an analysis of Eastwick, the flood impacts created by the Lower Darby Creek, and the viability of several potential flood mitigation strategies.

Flood mitigation approaches can be structural and nonstructural. Structural mitigation techniques focus on reconstructing landscapes, including building floodwalls/seawalls and installing floodgates/levees. Nonstructural measures work to reduce damage by removing people and property out of risk areas, including zoning, elevating structures, and conducting property buyouts.

For Eastwick, studying stream dynamics is a key component to determining what type of flood mitigation strategies will yield the most success, as well as identifying the approaches that don’t work for this unique area.

Princeton Hydro Senior Ecologist Christiana Pollack CFM, GISP participated in a workshop for Eastwick residents held by CCRUN and the Lower Darby Creek team. The goal of the workshop was to get the community’s input on the accuracy of the predictive models.Princeton Hydro’s study focused on the key problem areas in Eastwick: the confluence of Darby Creek and Cobbs Creek; a constriction at Hook Road and 84th Street; and the Clearview Landfill, which is part of the Lower Darby Creek Superfund site. Additionally, the study sought to answer questions commonly asked by community members related to flooding conditions, with the main question being: What impact does the landfill have on area flooding?

The built-up landfill is actually much higher than the stream bed, which creates a major disconnection between the floodplain and the stream channel. If the landfill didn’t exist, would the community still be at risk? If we increased the floodplain into the landfill, would that reduce neighborhood flooding?

Princeton Hydro set out to answer these questions by developing riverine flooding models primarily using data from US Army Corps of Engineers (USACE), Federal Emergency Management Agency (FEMA), The National Oceanic and Atmospheric Administration (NOAA), and NOAA's National Weather Service (NWS). FEMA looks at the impacts of 1% storms that are primarily caused by precipitation events as well as coastal storms and storm surge. NOAA looks at the impacts of hurricanes. And, NOAA's NWS estimates sea, lake and overland storm surge heights from hurricanes.

This is an example of a 2D model showing where the water is originating, how the water flows through the neighborhood, moves to the lower elevations, and eventually sits.

The models used 2D animation to show how the water flows in various scenarios, putting long-held assumptions to the test.

The models looked at several different strategies, including the complete removal of the Clearview Landfill, which many people anticipated would be the silver bullet to the area’s flooding. The modeling revealed, however, that those long-held assumptions were invalid. Although the landfill removal completely alters the flood dynamics, the neighborhood would still flood even if the landfill weren’t there. Additionally, the modeling showed that the landfill is actually acting as a levee for a large portion of the Eastwick community.

This model was developed to illustrate how the removal of the landfill impacts waterflow through the Eastwick community.

Ultimately, the research and modeling helped conclude that for the specific scenarios we studied, altering stream dynamics – a non-structural measure – is not a viable flood mitigation strategy.

The USACE is currently undergoing a study in collaboration with the Philadelphia Water Department to test the feasibility of a levee system (a structural control measure), which would protect the Eastwick community by diverting the flood water. Funding for the study is expected to be approved in the coming year.

Take a Deeper Look at Eastwick Flood Mitigation Efforts

There are many studies highlighting flood mitigation strategies, environmental justice, and climate change vulnerability in Eastwick. Princeton Hydro Senior Project Manager and Senior Ecologist, Christiana Pollack CFM, GISP, presented on the flooding in Eastwick at the Consortium for Climate Risk in the Urban Northeast Seminar held at Drexel University. The seminar also featured presentations from Michael Nairn of the University of Pennsylvania Urban Studies Department, Ashley DiCaro of Interface Studios, and Dr. Philip Orton of Stevens Institute of Technology.

You can watch the full seminar here:

For more information about Princeton Hydro’s flood management services, go here: http://bit.ly/PHfloodplain.

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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.

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When New Jersey Manufacturers Insurance Group
(NJM) developed their new Regional Operations Facility, a 55-acre corporate campus in Hammonton, New Jersey, they approached the construction with one major goal at the forefront: stormwater management.

Fundamental to that goal was designing a green infrastructure stormwater management system capable of containing on site nearly all the stormwater runoff generated by storm events up to and including a 100-year frequency, 24-hour duration storm.

The group hired Princeton Hydro, recognized as a leader in innovative, cost-effective, and environmentally sound stormwater management, to develop a concept plan that could be built within the context of proper stormwater management and meet the stringent requirements of the NJ Pinelands Comprehensive Management Plan.

To accomplish the ambitious stormwater management goals, the project team designed and implemented an integrated stormwater management system that combined traditional and green infrastructure components, and consisted of bioinfiltration basins, parking lot islands, a wetland basin, and a bioretention island. These features were designed to promote the interception, evapotranspiration, and infiltration of stormwater runoff at its source.

Emphasis was given to green infrastructure BMPs specifically capable of treating and infiltrating large volumes of runoff. Thus, all of the infiltration areas were designed using a soil amendment process where the underlying soils were excavated and amended with organic material to improve the underlying recharge capabilities of the soils. To complement the BMPs, the team designed and installed 120,000 gallon below-grade rainwater capture and reuse system. The system captures roof runoff to be used for on-site irrigation, which not only reduces stormwater volume but also decreases the facility’s water usage.

The project is one of the first projects in New Jersey built to infiltrate nearly 100% of the on-site runoff and uses site-design-based stormwater capacity to determine allowable impervious cover.

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Before construction began, the team implemented a comprehensive study, which began with a detailed analysis of the site’s soils, with particular attention given to physical properties of the soil and the depth to seasonal high water (groundwater). During construction, Princeton Hydro provided monitoring services for all earthwork activities. Our team was on site full-time during critical activities to ensure that the project was built in accordance with the intent of the original design and ensure the maintenance of the project schedule. The team also provided environmental and geotechnical design and engineering services throughout the corporate campus construction, including the analysis of subsurface structures shop drawings and providing consultation support to the general contractor.

For the project, we partnered with Burgis Associates, Inc. who created site designs, provided landscape architectural and professional planning services, and helped to obtain agency approvals. The landscape program sought to establish native plant communities that filter runoff, provide an aesthetically pleasing visual, reduce invasive species, create habitat for pollinators and other critical species, and require limited maintenance to stay healthy and flourishing.

Post construction, the Princeton Hydro team led the preparation of the scope of services, budget, and proposal for the Stormwater Basin Maintenance, which included mowing and clearing the vegetation in nine infiltration basins. The basins were inspected monthly for functionality and for the presence of invasive plants. And, we are happy to report that the basins are all working properly and invasive plants have been eradicated.

At Princeton Hydro, we are experts in stormwater management; we recognize the numerous benefits of green infrastructure; and we’ve been incorporating green infrastructure into our engineering designs since before the term was regularly used in the stormwater lexicon. Click below to read about a Stormwater Treatment Train we designed and implemented in Thompson Park, a 675-acre recreation area in Middlesex County, New Jersey.

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