by Lee Koska, PE, Weston & Sampson

A Community Facility with a Long History

Every year, millions of tons of municipal solid waste flow through Massachusetts for disposal. Though most people don’t think about their trash every day, the strategies for dealing with these literal mountains of waste have evolved over the decades. Across the state, the closure of many “town dumps” over the last 30 years means that solid waste has been increasingly diverted to other locations for final disposal, including incinerators, regional landfills, or out of state. To support these changes in disposal practices, many town dumps were converted into transfer stations where residents and commercial haulers drop off waste and recycling.

Beyond acting as a transportation nexus, transfer stations have also become a focal point of the local community. A social gathering point, each transfer station is a unique but surprisingly beloved town fixture. 

Removing the Past to Build the Future

In Winchester, their transfer station was also originally the town’s landfill before the advent of modern regulations. In the 1960s, an incinerator was built on the site to burn waste and reduce overall volume, but it only operated until the 1970s. The site was subsequently converted to the transfer station with the incinerator itself remaining largely unused for decades. 

In 2020, when the town decided to move forward with much needed repairs and improvements to the transfer station, Manager Nick Parlee saw an opportunity to modernize and upgrade it to meet current trends and standards for solid waste and recycling. To help, he hired Weston & Sampson to design and permit the facility and maximize the use of about $6 million in allocated funds in support of a more modern facility.

First and foremost, the old incinerator had to go. Located in the center of the site, it acted as a barrier to traffic flow and took up valuable real estate and, having sat abandoned since its closure, had fallen into disrepair. The structure also housed the site’s electrical connection, which was in jeopardy due to the deteriorating building condition. Following abatement of asbestos lining the furnaces, removal of decades of pigeon guano, and disposal of residual hazardous materials remaining in the burn chambers for 50 years, the building was reduced to a pile of bricks in the span of a single weekend.  

The impacts from the incinerator however were not limited to traffic challenges and an eyesore. Despite having only operated for about 10 years, it had nonetheless resulted in large volumes of ash underneath both the transfer station and the nearby high school. Capped in the 2000s, the on-site ash exhibited high concentrations of lead and other heavy metals and required careful handling during construction.  

Just south of the old incinerator, a new elevated recycling area was constructed for resident and commercial recycling dropoff which allowed better traffic flow and improved safety by keeping the residents separated from facility vehicles and waste handling operations. To support its construction, however, an existing hillside needed to be excavated, which required management of hundreds of tons of contaminated material.

Managing Legacy Contamination

Soil and ash under the recycling area exhibited elevated concentrations of leachable lead that required stabilization prior to off-site disposal. An additive was used to bind the metals into a solid crystalline matrix and render it safe to transport and dispose. Federal RCRA regulations required this work to be done within the excavation area without moving the soil and for testing to be done on every 100 tons of soil to verify effectiveness.

Elevated lead was not the only contaminant issue at the site. During the precharacterization phase, we identified an area of polychlorinated biphenyl (PCB) impacts near the scrap metal handling area. Although the source of the PCB impacts was initially unknown, interviews with facility staff determined that several transformers were once brought to the transfer station by an outside contractor and dumped in this area for the town to manage. Oil from these transformers then leaked into the ground, forming a localized area of impacts. Since concentrations exceeded regulatory thresholds and the date of the spill was estimated to have occurred in 1992, we determined that Toxic Substances Recovery Act (TSCA) cleanup regulations applied.

Following several rounds of sampling, the material was ultimately excavated and disposed of at an out-of-state TSCA landfill, along with an Activity and Use Limitation (AUL) filed for the area. This required that the area remain free of structures and that an expanded concrete material pad be maintained as a cap over residual contamination.

Completed in 2024, facility improvements have greatly modernized a vital piece of town infrastructure, but Nick Parlee had further plans for the facility. Through state grant funding, the town procured an anaerobic digestor to process food waste from the local middle school and other residential and commercial sources. The residuals from this process are added to the existing compost operation to enrich the final material, which is provided free to town residents to use.

The town is also now looking at opportunities to install a large solar array on an awning system to both provide renewable energy revenue and to protect residents from the rain and snow when dropping off their recyclables and waste. Weston & Sampson continues to work closely with the town by supporting the permitting and engineering efforts for these follow-on projects.

A Model for Sustainable Waste Management

The Winchester transfer station exemplifies the changes in solid waste management over the last 100 years. From a town dump to an incinerator to a capped landfill and modern transfer station, the facility has continuously evolved to meet the needs of both the community and increasing environmental regulation. Now pivoting into renewable energy and food waste management, the town remains at the forefront of municipal waste management. Through the efforts of Nick Parlee and many others, the town is well positioned for changes in waste disposal regulations for decades to come.

The Author:

Lee Koska, PE (MA), is a Remediation Team Leader at Weston & Sampson in Reading, Massachusetts. He can be reached at koskal@wseinc.com.

EPA’s early fiscal year 2027 outlook points to a smaller federal funding pool, fewer grant pathways and a growing advantage for communities that prepare before solicitations open

By Derek Street, Brownfields & Community Revitalization Practice, Onterris

Federal investment has expanded what communities can accomplish through the U.S. Environmental Protection Agency (EPA) Brownfields Program. The next funding cycle will test how well applicants can convert that momentum into focused, achievable projects.

The Bipartisan Infrastructure Law (BIL), formally the Infrastructure Investment and Jobs Act, provided an additional $1.5 billion for the EPA Brownfields Program through a five-year funding initiative. That temporary expansion supported larger applications, broader project pipelines and more ambitious redevelopment strategies across the country.

It also created expectations around federal capacity that were never intended to continue indefinitely.

As BIL support winds down, brownfields funding is not disappearing. EPA continues to make awards and support assessment, cleanup and redevelopment. The change is one of scale and competition. Communities will likely pursue a smaller pool of funding under tighter program parameters, making project selection and application quality increasingly important.

EPA’s preliminary outlook for fiscal year 2027 provides an early view of that transition. The agency expects to publish solicitations for Assessment, Revolving Loan Fund and Cleanup grants in fall 2026. Applications are expected to close about 60 calendar days after publication.

That window leaves little time to resolve site access, confirm eligibility, gather community evidence or establish redevelopment partnerships. Applicants that wait for the final Notice of Funding Opportunity will begin the competition behind communities that have already completed those steps.

A $64 Million Planning Framework Changes the Competitive Equation

EPA’s current fiscal year 2027 planning assumptions identify $64 million across five anticipated grant competitions:

• $15 million for Community-wide Assessment Grants
• $13 million for Assessment Coalition Grants
• $12 million for Community-wide Assessment Grants for States and Tribes
• $10 million for Revolving Loan Fund Grants
• $14 million for Cleanup Grants

EPA cautions that these figures may change. The agency has also indicated that it does not expect to offer a Multipurpose Grant competition in fiscal year 2027.

The absence of Multipurpose Grants is a significant planning constraint. These awards have allowed recipients to combine eligible assessment, cleanup and planning work within one grant structure. Communities that might previously have assembled those activities under a single application must now determine which available funding category best matches their immediate needs and delivery capacity.

The decision should begin with the project, not the funding announcement.

A community with several promising properties but limited environmental information may benefit most from a Community-wide Assessment Grant. A municipality with control of a priority site and a credible redevelopment plan may be better positioned for Cleanup funding. Regional applicants may find that an Assessment Coalition aligns with their shared geography and capacity. Communities with recurring cleanup financing needs may consider a Revolving Loan Fund (RLF), provided they can manage the additional financial and administrative responsibilities.

The goal is not simply to submit an application. It is to pursue the funding opportunity that best aligns with the project's needs and the community's capacity to deliver results.

The Program’s Public Value Has Not Changed

A smaller funding pool does not reduce the importance of brownfields work.

Underused and contaminated properties can constrain housing development, weaken commercial corridors, depress property values and create environmental or public health concerns. When communities address those sites strategically, the land can support housing development, business activity, public facilities, renewable energy, health services, recreation and other productive uses.

As of July 1, 2026, EPA reports that its Brownfields and Land Revitalization work has helped communities:

• Assess 43,397 properties
• Complete cleanup at 3,106 properties
• Prepare 13,236 properties for anticipated reuse
• Leverage $46 billion
• Support 230,503 jobs

These results help explain the program’s continuing appeal across political and geographic lines. They also show why demand is unlikely to decline simply because supplemental BIL funding is ending.

Through fiscal year 2025, EPA reports that each Brownfields Grant dollar awarded leveraged an average of $19.47. The agency also reports an average of 10 jobs leveraged for every $100,000 awarded.

Annual Appropriations Will Again Set the Boundaries

EPA has stated that fiscal year 2027 Brownfields Grants will rely entirely on annual appropriations for the Brownfields and Land Revitalization Program.

That return to annual funding means applicants should develop their strategies around existing statutory limits rather than the larger capacity available during the BIL-supported period. Under current requirements, assessment spending may not exceed $200,000 for an individual site. Cleanup and RLF recipients must also provide a 20% cost share or match.

Potential federal legislation could change parts of the program, but applicants should not treat proposed reforms as current policy.

The Senate Environment and Public Works Committee unanimously advanced S. 347, the Brownfields Reauthorization Act of 2025, on February 5, 2025 and the bill was placed on the Senate legislative calendar. In March 2026, the House Energy and Commerce Subcommittee on Environment examined several brownfields proposals. On May 14, 2026, the subcommittee reported H.R. 8739, the Brownfields Revitalization for a Better Tomorrow Act, to the full committee by voice vote.

Options discussed through the legislative process include higher award limits, revised cost-share provisions, broader eligibility, additional rural support and new financing mechanisms. These proposals indicate continued interest in brownfields redevelopment, but they have not yet replaced the rules governing current applications.

The Congressional Budget Office estimate for S. 347 states that the bill would authorize $200 million per year from 2025 through 2030 for Brownfields Program grants under CERCLA Section 104(k). It would also authorize $375 million over that same period for state response programs, subject to congressional appropriations.

Authorization does not guarantee that Congress will provide the full amount. Until new legislation is enacted and funded, communities should prepare applications that comply with the program as it exists today. A project that works under current requirements can be adjusted if Congress later expands the available tools. A project that depends on an unpassed provision may not be ready when the application period opens.

Funding Access Is Part of Project Risk

The amount awarded is only one part of a brownfields financing strategy. The timing and accessibility of that funding also affect whether redevelopment remains on schedule.

In early 2025, the Naugatuck Valley Council of Governments reported that it lost access to a fiscal year 2022 RLF award totaling $8,661,808 following federal action associated with executive orders issued by President Trump. The council said the suspension affected 13 projects involving housing, private development and regional revitalization.

Connecticut lawmakers similarly reported that the organization could not draw an approximately $8.66 million balance through the federal payment portal.

Those cases should not be interpreted as representative of every Brownfields Grant. EPA has continued to announce selections and administer funding opportunities. It does, however, demonstrate how an administrative delay can affect projects that rely on coordinated financing, property transactions, construction schedules or private partners.

Applicants should account for that possibility before an award is made. A resilient funding strategy addresses the documentation requirements, drawdown timing, supplemental financing and steps required to preserve project momentum if federal reviews delay access to funds.

Five Disciplines Can Strengthen a Fiscal Year 2027 Application

A more selective competition does not make funding unattainable. It makes disciplined preparation more valuable.

Match the project to the correct grant

The first step is to examine the purpose and requirements of every expected grant type rather than defaulting to the category applicants may have pursued before. The lack of a Multipurpose competition makes this evaluation especially important.

The selected grant should correspond to the project’s current stage. Assessment funding advances sites that need environmental investigation. Cleanup funding supports properties with sufficient characterization, ownership and reuse direction. An RLF addresses a repeatable financing need rather than function as a one-time substitute for an individual Cleanup Grant.

Support the target area with evidence

General statements about contamination or community decline are unlikely to make an application stand out.

Connect the proposed target area to documented local conditions in the application. Useful evidence may include vacancy, historic disinvestment, housing demand, health concerns, infrastructure plans, environmental burdens, employment needs or adopted economic development priorities.

The strongest data establishes both need and consequence. It explains why the area requires intervention and what the community could gain when specific properties return to use.

Present a credible group of sites

A lengthy inventory does not necessarily demonstrate readiness. A focused pipeline of eligible properties with identifiable next steps can provide a clearer case for investment.

For each priority site, applicants should understand ownership, access, known or suspected contamination, past uses and likely redevelopment potential. It’s also important  to explain how the proposed assessment or cleanup activity will remove a barrier to reuse.

The site list should function as an implementation plan, not a collection of possibilities.

Explain what follows the environmental work

EPA funding often serves as a catalyst rather than the sole source of redevelopment capital.

Include details that describe how assessment findings, cleanup activities or RLF financing will connect to later action. That explanation may address site control, development partners, public approvals, infrastructure, market feasibility, community engagement and potential public or private financing.

A technically sound cleanup strategy becomes more competitive when reviewers can see the route from environmental work to community benefit.

Request an amount the project can use well

Larger requests do not automatically create stronger applications.

In a limited funding cycle, a carefully scoped request may be more persuasive than a larger proposal that relies on unresolved property access, uncertain matching funds or speculative redevelopment assumptions.

Align the budget with work that can be reasonably completed within the grant period. For Cleanup and RLF applications, incorporate the required 20% match into the financing plan from the beginning. Those applying for an Assessment Coalition Grant will need to consider the $200,000 per-site limit when determining how many properties the proposed work can credibly advance.

Revolving Loan Funds Require Institutional Capacity

An RLF can extend the value of federal investment beyond a single project. Recipients use the award to issue cleanup loans and subgrants. Loan repayments return to the fund and may support later projects.

That revolving structure also creates operational demands that do not apply to every grant category. EPA expects recipients to demonstrate capabilities in real estate finance, credit analysis, loan servicing, compliance and long-term program administration.

EPA’s preliminary fiscal year 2027 framework anticipates:

• A maximum five-year project period
• Awards of up to $1 million
• Approximately 10 awards
• $10 million in total RLF funding
• A 20% cost share or match

Applicants will need to establish more than environmental need. They should show that they can build a project pipeline, complete financial review, structure loans or subgrants, monitor performance and move funds efficiently after receiving an award.

Existing RLF recipients should maintain accurate performance records and keep viable cleanup projects ready. They should also expect close attention to spending, compliance and demonstrated outcomes.

Communities without an RLF should assess whether creating one supports their long-term redevelopment strategy. In some cases, working with an established recipient or joining a coalition may provide a more practical path than building a new fund administration program.

Limited Funding Can Improve Project Selection

The end of BIL expansion creates a real financial constraint. It also provides an opportunity to improve how communities prioritize brownfield properties.

During periods of higher funding, a project may advance largely because it qualifies. Under tighter conditions, eligibility becomes the starting point. The project must also be distinct, feasible and supported by a credible route to reuse.

That pressure can produce stronger investment decisions. Communities can focus resources on properties where environmental work will remove a defined barrier, where partners are prepared to act and where redevelopment can produce measurable public value.

The right question is not, “How large a grant can we pursue?”

It is, “Which sites can move from uncertainty toward productive use during the grant period?”

The answer will determine the application’s scope.

Start Preparing Brownfield Grant Applications Before Fall 2026

Fiscal year 2027 begins October 1, 2026. With EPA anticipating fall solicitations and an application period of about 60 days, the practical preparation window is already open.

Communities can act now by:

• Confirming applicant and site eligibility
• Establishing property ownership, access or control
• Prioritizing sites with achievable reuse potential
• Documenting environmental, economic and community needs
• Selecting the most appropriate grant category
• Defining partner responsibilities
• Developing a realistic scope, schedule and budget
• Identifying the 20% match for Cleanup or RLF applications
• Planning for funding delays or administrative review
• Connecting environmental activities to redevelopment financing

Continue monitoring EPA guidance because anticipated amounts, dates and requirements may change before the final solicitations are released. Early preparation does not mean assuming the preliminary framework is final. It means completing the work that will remain useful under most versions of the competition.

Brownfields redevelopment has never depended on funding alone. Progress requires technical evidence, community trust, sustained coordination and a feasible vision for reuse.

The fiscal year 2027 cycle will place greater weight on those fundamentals. Communities that select the correct funding route, narrow the scope to executable work and demonstrate how federal support will unlock lasting benefits will enter the competition with the strongest case.

The Author:

Derek Street is a Principal Geologist with Onterris, specializing in brownfields and community revitalization. Prior to joining the private sector, Derek served with U.S. EPA Region 4, where his work focused on Brownfields grants, Revolving Loan Fund programs, grant implementation and compliance, and land revitalization initiatives. Today, he works with communities, regional organizations, and other public-sector partners across the country to develop and implement brownfields strategies, navigate federal funding requirements, and advance contaminated and underutilized properties toward productive reuse.

By Joel Kane, Fleming Lee Shue

When it comes to environmental contamination and its effect on living things, there is a tendency to see the relationship as fairly black and white. Typically, as environmental professionals we view any level of contamination as bad. However, some scientists have presented that the relationship might not be that simple.

The Hormetic Effect or “hormesis” occurs when a living thing has a two-phase response to a contaminant. In certain doses the response to the stressor is positive (beneficial) and in other doses it is negative. For example, a very small dose of zinc can boost your immune system, but high doses can poison you.

This process is typically thought to be an adaptive response to stress (in this case the contamination)—the “low dose contaminant stress” triggers overzealous cellular repair and maintenance. This overcompensation of the cell in turn produces a low-dose beneficial effect. Similar to how frequently performing maintenance on your car—like changing oil and rotating your tires would be beneficial. However, the most interesting instances of hormesis occur when low doses of harmful environmental toxins are shown to be beneficial.

For decades toxicologists have studied and confirmed the linear trend of mid-to-high dose response to environmental contaminants (E.g. Mercury is bad for you, more mercury is even worse). This is generally referred to as the linear, no threshold (LNT) dose response. It assumes that a contaminant proven to be dangerous at high concentrations—will be dangerous at any concentration. However, a movement of toxicologists have argued that hormetic response curves (see figure below) exist in the relationships between hundreds of environmental contaminants and living things.

For example, low doses of heavy metals have been shown to potentially show some benefit to stream ecosystems.¹ Low doses of dioxin have been shown to reduce tumor risk in rats.² Some crop growth was stimulated by low concentrations of hexavalent chromium.³ Low concentrations of crude oil have been shown to potentially benefit certain plant growth.⁴ Hormesis was also cited in the Trump Administration’s arguments to lower the regulatory guidance values for various contaminants including—radiation.⁵

What Does this Mean for Environmental Consulting? 

So, what does this mean? Could hormetic dose response change the way we view environmental contamination? Should regulations change—cleanup standards be reduced? Should all citizens demand 5 ppb chromium be included in their drinking water? In short, definitely no.

Although a fascinating scientific phenomenon, most toxicologists argue that the “benefits” of hormesis are not even close to being worth the risks that a regulatory reworking could have on public health. In fact, the majority of environmental experts have criticized recent hormesis support by the Trump Administration, citing it as a flimsy pretext to weaken environmental regulations of well-known toxic substances.⁶

The truth is, hormesis is often based on a small sample size and individual responses to specific chemicals, i.e. what is beneficial for some—could still potentially adversely affect others. Furthermore, many hormesis studies examine these dose relationships in a lab setting. In real-world conditions, toxins regularly mix and interact, which can vastly alter their effect on the population. The unpredictable and often unreproducible nature of hormesis in real-world conditions means that responsible regulation should mandate that a conservative approach be applied to contaminant thresholds and guidance values. One that is inclusive of all people.

Ultimately, hormesis reminds us that environmental science is rarely as simple as it first appears. Although hormesis alone should not dictate how environmental cleanup standards are established, it illustrates why environmental professionals must remain curious, engage with emerging evidence, and allow evolving science to sharpen how we investigate sites, evaluate risk, and design remedies. As environmental professionals we need to approach that responsibility first and foremost as scientists, keeping our staff at the forefront of the field so we can provide our clients with advice that is both technically sound and practical. 

1.Lefcort, Hugh, Freedman, Zachary. “Hormetic Effects of Heavy Metals in Aquatic Snails: Is a Little Bit of Pollution Good?” Ecohealth, 2008.  

2.Calabrese, Edward. “Paradigm Lost, Paradigm Found: The Re-emergence of Hormesis as a Fundamental Dose Response Model in the Toxicological Sciences.” Environmental Pollution, 2005.  

3.Patnaik, Anita, Achary V. Mohan. “Chromium (VI)-induced Hormesis and Genotoxicity are Mediated Through Oxidative Stress in Root Cells of Allium cepa L.” Plant Growth Regulation, 2013 

4.Carr, R. “Vegetative Growth in Soils Containing Crude Petroleum.” Soil Sciences. 1919.  

5.Malone, Patrick. “Radiation Is Good for You? The Heretical View Gains Ground Under Trump.” Center for Public Integrity, 27 February 2019.  

6.Rust, Susanne. “Scientist Says Some Pollution is Good for You—a Disputed Claim Trump’s EPA Has Embraced.” Los Angeles Times, 19 February 2019.  

The Author:

Joel Kane is a Senior Associate at Fleming Lee Shue, where he oversees the firm’s technical operations and manages a diverse portfolio of remediation projects across the greater New York Metropolitan Area. He specializes in complex remediation sites and his experience spans both the public and private sectors.

By Jeremiah Duncan, Ph.D., GZA GeoEnvironmental

Per- and polyfluoroalkyl substances, or PFAS, are well known as contaminants at this point. However, it is less well-known and may be surprising to both regulators and owners that many PFAS are not currently detectable but do transform in the environment to detectable and regulated PFAS. In fact, there were many more of these compounds, known as “precursors,” used commercially than the ones you have probably heard of (e.g., PFOA and PFOS). In this blog, we’ll discuss what these precursors are, and how to anticipate the regulatory concerns they might raise.

There are tens of thousands of PFAS, but only about 1,400 of them have seen any form of commercial production; of those, about 256 compounds were sold in large quantities on the market for any sort of industrial use, making them the most likely to be encountered in the environment. Of all the known PFAS, the most common analytical techniques test for up to 40, and only a handful of compounds are regulated.

In short, the regulated compounds are barely the tip of the PFAS iceberg. Many of those other PFAS that aren’t regulated can, with time, transform into compounds that are regulated. While the strength of the carbon-fluorine bond has given PFAS the nickname “forever chemicals,” those aren’t the only bonds in these compounds. The weaker bonds in precursors can break down over time, until what remains is primarily the original portion of the molecule with fluorinated remains, and you are left with a molecule like PFOA or PFOS. For this reason, PFOA, PFOS, and related molecules with longer or shorter fluorinated carbons chains are often termed “terminal” compounds.

Imagine an arrow—with fletching, a shaft, and an arrowhead—embedded in a tree. Over time, the fletching may drop away, the shaft may snap or degrade, but the arrowhead will remain in the tree. PFAS compounds can act much the same way, with the terminal PFAS (e.g., PFOS) as the arrowhead, in your water and soil.

Because most of these precursors cannot currently be measured in environmental samples, they are the “unknown unknowns” of the PFAS world—and they may be a source of detectable, regulated compounds. The good news is that, while we cannot currently test for them, these precursors aren’t completely invisible, if you know how to look. The Total Oxidizable Precursor (TOP) Assay, for example, uses an oxidant and heat to transform the precursors in a sample, and then test for the terminal PFAS. Knowledge is power. Knowing whether there may be precursors slowly transforming into regulated compounds can anticipate future problems on a site, inform remediation plans, and in some cases, be used to demonstrate that the responsibility for the contamination lies elsewhere.

For developers and owners, it’s key to take the following steps:

• Determine, as much as possible, what the history of your site is, focusing on what was manufactured or used on site and whether it might include any form of PFAS. 
• Work with your due diligence team to find records of all PFAS that might have been used, not just regulated ones.
• Remember that precursors can transform over a lengthy timeframe, and they may not degrade completely. Speak with a project manager about whether a TOP assay may be advisable.
• Stay abreast of regulatory changes, especially ones that regulate PFAS as a class, instead of individual compounds.

 We often talk about PFAS in environmental or hydrological terms, but it’s important to remember the key role chemistry plays with these compounds. By knowing the chemistry of what was used on your site, you can plan more effectively for regulatory risk.

The Author:

Jeremiah Duncan, Ph.D. Dr. Duncan is a Senior Chemist with the Environmental Remediation and Environmental Site Investigation Groups at GZA GeoEnvironmental, Inc. He provides specialized expertise in analytical and environmental chemistry, based on more than 25 years of consulting and academic experience. He also held an AAAS fellowship at the U.S. EPA in Washington, DC working on regulation of emerging contaminants and the environmental implications and applications of nanomaterials. He currently serves on a working group with the National Ground Water Association to co-author a white paper on PFAS forensics. Contact him at Jeremiah.Duncan@GZA.com or 603-707-3204.

By Daniel Claycomb, P.G. and Joe Kraycik, P.G., CQA, Integral Consulting, Inc. 

The Women’s Community Revitalization Project (WCRP) is a Philadelphia based, women led nonprofit dedicated to advancing social and economic equity for low income women and their families through the development of affordable housing, the provision of supportive services, and advocacy for equitable public policy.

Founded in 1987, WCRP emerged from grassroots organizing in North Philadelphia after local women successfully challenged discriminatory lending practices, leveraging the momentum to address neighborhood disinvestment and housing instability. The organization involves residents and neighbors in their design to ensure homes meet the real-life needs of the families who live there.

Over the last 40 years the organization has grown to become a nationally recognized, innovative developer that has built more than 414 units of housing and invested $155 million in some of Philadelphia’s poorest neighborhoods.

Integral Consulting, Inc. (Integral) has provided environmental consulting services to WCRP on three recent projects. Each project was developed on brownfield sites owned by a community land trust. 

Linda Lockman King Apartments

WCRP recently celebrated the groundbreaking of the Linda Lockman King Apartments, a new affordable housing development located at 5500 Haverford Avenue in West Philadelphia. The event marked an important milestone in WCRP’s ongoing commitment to creating stable, permanently affordable housing for low income Philadelphians, particularly women and their families. 

The Linda Lockman King Apartments are designed to remain affordable for generations to come. The four story building will include 33 rental units, with nine units fully wheelchair accessible. Twenty three of the apartments will be supported by the Philadelphia Housing Authority, helping ensure access for families most in need.

The development is named in honor of Linda Lockman King, a beloved West Philadelphia community leader and social worker known for her tireless dedication to neighborhood families. King organized free food programs, coordinated youth summer initiatives, and dreamed of transforming land across from Philadelphia Baptist Church into affordable housing—a vision now brought to life through this project.

In addition to developing and managing the property, WCRP will provide on site supportive services for residents, reinforcing its holistic approach to housing. Once completed, the Linda Lockman King Apartments will provide a safe, affordable home for 33 Philadelphia families, strengthening the surrounding community and advancing the city’s broader efforts to address housing insecurity.

Integral conducted Phase I Environmental Site Assessment (ESA); Phase II investigations involving soil, groundwater, and vapor intrusion evaluations; U.S. Department of Housing and Urban Development (HUD) evaluations including Noise Abatement and Control Analysis and Explosive and Flammable Facilities Analysis; preparation of a Soil Management Plan; oversight of smoke testing associated with vapor barrier installation; and provided oversight and consulting during redevelopment activities. 

Abigail Pankey Apartments

Another WCRP project, the Abigail Pankey Apartments, was completed in early 2026 in West Philadelphia’s Mantua neighborhood. This apartment complex consists of 32 units including 22 two-bedroom and 10 three-bedroom units, all suited for families with children. Eight apartments are fully accessible for individuals with disabilities and two are sensory units designed for individuals with hearing and visual differences. 

Abigail Pankey Apartments were built within a rapidly changing neighborhood that has received multiple revitalization designations, including HUD Choice Neighborhood, Promise Zone, and Opportunity Zone status. These programs reflect the community’s commitment to revitalization while preserving affordability. The project addresses the urgent need for affordable housing as market-rate development accelerates, threatening to displace low- and moderate-income families. By activating previously vacant land, the development creates much-needed homes while also improving neighborhood safety and property values.

The development is named in honor of Abigail Pankey who was a leader of the Mantua Housing Committee and co-founder of the Philadelphia Anti-Poverty Coalition (Women's Community Revitalization Project, Abigail Pankey Apartments announcement, March 2026). She understood housing not as an abstraction or a policy problem, but as the foundation of everything else a community needs: safety, stability, the ability to stay.

Integral also provided environmental consulting services to WCRP on this project. These services included Remedial Investigation Report and Cleanup Plan Addendum Preparation; Phase II investigations involving soil, groundwater, and vapor intrusion evaluations; underground storage tank removal efforts; preparation of a Soil Management Plan; oversight of smoke testing associated with vapor barrier installation; redevelopment oversight and consulting, and reporting under Pennsylvania’s Voluntary Cleanup Program in order to obtain a  site-specific release of liability associated with historical environmental impacts at the property. 

Nayda Cintron Apartments

Nayda Cintron Apartments is a 40-unit, new construction affordable housing community located in the Fairhill neighborhood of North Philadelphia. Being developed by WCRP on land donated by the City of Philadelphia, the project will span 0.97 acres across 11 parcels. It will consist of a three-story, 34-unit multifamily building and two three-story triplexes situated on separate parcels across Fairhill Street. The multifamily building includes 2 one-bedroom units, 23 two-bedroom units, and 9 three-bedroom units, while each triplex contains two bi-level three-bedroom units and one single-level ADA-accessible three-bedroom unit. In total, the development will offer 10 fully ADA-accessible units, 2 units designed for hearing or visual impairments, and 36 Visit Able units.

The $25.3 million development will transform multiple vacant and blighted parcels into high-quality, energy-efficient homes designed to meet Zero Energy Ready Homes standards and Enterprise Green Communities criteria. The site is within walking distance of schools, parks, libraries, recreation centers, and local employment opportunities, making it ideal for families. Larger unit sizes will address a critical shortage of affordable housing for bigger households, helping to combat overcrowding and substandard living conditions in the area. The design and site plan take advantage of by-right zoning, which expedites the development process and supports neighborhood revitalization. Environmentally sustainable materials, efficient systems, and thoughtful urban design will enhance both livability and long-term operational savings.

The development is named in honor of Nayda Cintron who is a prominent Puerto Rican activist and community organizer in Philadelphia, best known for her foundational work in the Norris Square neighborhood during the 1980’s during which she organized residents to challenge a system that split the Norris Square community across multiple council districts. She founded the Norris Square Civic Association (now known as Xiente), establishing a model for grassroots community control over housing, zoning, and safety. She also helped launch the American Street Business Corridor and introduced some of the city's first community gardens, land banks, and job training programs.

Integral has provided environmental consulting services to WCRP on this project. These services included a Phase I ESA; Phase II investigation involving soil and vapor intrusion evaluations; HUD-required evaluations including Noise Abatement and Control Analysis and Explosive and Flammable Facilities Analysis; and redevelopment oversight and consulting.

To learn more about WCRP, please visit www.wcrpphila.org

Integral Consulting, Inc. is a multidisciplinary environmental consulting firm that helps clients make informed, strategic, and compliant decisions on complex environmental and human health issues. The company brings together scientists, engineers, and regulatory specialists to deliver practical, technically rigorous solutions, emphasizing collaboration, clear communication, and results that balance scientific precision with real world feasibility.

https://www.integral-corp.com/about/

The Authors:

Mr. Claycomb has more than 38 years of experience as a geologist with engineering and environmental consulting firms. His work focuses on quality assurance oversight for environmental emergency response, as well as emergency response planning and preparedness documents related to sampling, analytical, and data management programs. He also provides technical support for environmental litigation, risk-based investigations and corrective actions, Pennsylvania’s Land Recycling Program (Act 2) and Management of Fill Policy, sediment and surface water quality investigations, quality assurance oversight for major surface water bodies, and environmental investigations involving vapor intrusion, subsurface soil and rock exploration, and groundwater contamination.

Mr. Kraycik is a professional geologist with 30 years of environmental consulting experience. He is an effective and successful manager who has been recognized with four prestigious brownfield redevelopment excellence awards for public and private projects in EPA Region 3. He has managed numerous EPA and state grants on behalf of clients throughout the northeast and mid-Atlantic with an emphasis on best practices for establishing sustainable assessment and redevelopment programs.

by James P. Cinelli, P.E., P.G., BCEE, Liberty Environmental

When designing sub-slab depressurization systems (SSDSs) for vapor intrusion mitigation, several key steps in the evaluation and design process are critical to avoid over- or under-designing the system. A few of these are outlined below.

Seal Off Entry Points

After confirming that vapor intrusion is a concern—and before beginning system design—identify and seal all potential vapor entry points, then retest indoor air. Eliminating preferential pathways may be sufficient to meet indoor air quality goals without additional mitigation.

If further mitigation is required, sealing entry points also helps prevent system failures caused by short-circuiting.

Perform Pressure Field Extension (PFE) Testing on Existing Buildings

In older buildings, the gravel layer beneath slabs and foundations may be thin or absent, limiting how far a vacuum can extend from a depressurization point.

Pressure Field Extension (PFE) testing—also known as communication testing—involves applying vacuums at varying strengths and locations to determine:

• the radius of influence, and
• the vacuum required for effective depressurization

Designers use these data to determine fan sizing and riser placement, making PFE testing a critical step in the design process.

Design New Buildings According to ANSI/AARST Standards

New construction typically includes a porous gravel layer (the “soil gas collection plenum”) beneath slabs and foundations. ANSI/AARST standards guide the design by specifying:

• appropriate gravel types (e.g., AASHTO #5, #7, #57),
• gravel thickness (e.g., 4", 6"), and
• pipe diameters (e.g., 3", 4", 6")

The number of extraction points (risers) is determined using standard guidelines based on floor area, rather than field testing. Factors influencing the number of risers include:

• Riser diameter
• Presence of a vapor barrier
• Thickness of the gas-permeable layer
• Ability to inspect the plenum

Inspect System Installation During Construction

ANSI/AARST standards allow for fewer extraction points when inspections are performed during installation of the soil gas collection plenum. This is because improper material selection or placement can significantly reduce system performance.

Additionally, foundation configurations often change during construction. For these reasons, frequent inspections during plenum installation and foundation work are strongly recommended.

Conclusion

Effective vapor intrusion mitigation depends on a thoughtful, data-driven approach that integrates site conditions, sound design principles, and careful construction oversight. By sealing entry points, conducting appropriate testing, adhering to established standards, and verifying installation quality, practitioners can develop systems that are both efficient and reliable. Taking these steps not only improves system performance but also reduces the risk of long-term operational issues, helping ensure that indoor air quality objectives are consistently achieved.

The Author:

James P. Cinelli is an environmental engineer and the president of Liberty Environmental, Inc., an environmental consulting firm which he co-founded in 2004. Mr. Cinelli has over 30 years of experience in environmental consulting with an emphasis in the areas of soil & groundwater remediation, brownfield redevelopment, and water resource engineering. He has provided expert witness testimony and has spoken at state and national conferences on topics such as stormwater management, erosion control, site remediation, and spill prevention.

By David Shea, P.E.

Environmental due diligence for potentially contaminated properties should include an assessment of vapor intrusion risk, among other environmental concerns. Vapor intrusion is defined by U.S. EPA as the migration of hazardous vapors from any subsurface contaminant source, such as contaminated soil or groundwater or contaminated conduits, into an overlying building or structure through any opening or conduit. [1] The ultimate concern with vapor intrusion is the potential for human exposure to hazardous vapors in indoor air. Figure 1 illustrates potential vapor intrusion pathways from subsurface contamination.

Vapor intrusion has been a recognized human exposure risk since the 1980s, with concerns centered on radon entry into homes and schools. Radon is a colorless, odorless, radioactive gas that is naturally occurring in soil in many parts of the United States. The awareness of radon intrusion foreshadowed concerns associated with properties containing subsurface vapor-forming chemicals (VFCs). Some common VFCs responsible for vapor intrusion are: perchloroethylene (PCE), often associated with dry cleaner releases; trichloroethylene (TCE), often found at industrial sites; and benzene, often connected to hydrocarbon releases. Since these VFCs and others may also be found in consumer products, distinguishing vapor intrusion from indoor sources of air quality concerns can be an investigation challenge. 

Most states, in addition to U.S. EPA, have published technical guidance for assessing and mitigating vapor intrusion. [2] Potential vapor migration (i.e., the movement of hazardous vapors in the subsurface) is included in the scope of an ASTM E1527-21 Phase I Environmental Site Assessment, [3] while ASTM E2600-22 is a guide for evaluating vapor encroachment, defined as the presence of contaminated vapors at a subject property due to an on-site or off-site release. [4]

Conventional Assessment Approach Takes Time

Despite the long-standing awareness of vapor intrusion risk and its inclusion in the scope of property transaction due diligence, as well as the thousands of properties that have been identified with potential vapor intrusion concerns, little has changed or improved over the past two decades in the methods typically used to investigate and test most of these sites. The conventional vapor intrusion assessment approach is to collect samples of soil vapor from either below a building (termed sub-slab vapor samples) or from outside the building footprint (termed exterior soil vapor samples), oftentimes in combination with indoor air samples. The samples are then sent to a laboratory for analysis of volatile organic chemicals (VOCs). The steps are often repeated to address data gaps or new questions arising from the initial results. With laboratory wait times of several weeks, followed by data analysis and reporting, this can be a drawn-out process if multiple sampling events are required to address uncertainties and data gaps – an undesirable situation when human health, environmental impact, and business interests in the property are in question. 

Furthermore, vapor intrusion is an inherently highly variable and structure-specific phenomenon as reflected in highly variable VOC concentrations in indoor air over periods ranging from hours to months. [5] A single, conventional sampling event is unlikely to provide an accurate representation of the vapor intrusion risk. Thus, many states require multiple sampling events across different seasons, including the winter in the northeast when vapor intrusion is more likely to occur due to the stack effect (i.e., when indoor-outdoor temperature differences drive indoor convection currents that favor drawing soil vapor into a structure). As a result, a vapor intrusion investigation that adequately assesses the indoor air exposure risk can take months to years using conventional methods.

Adaptive Investigations Using Real-Time Analysis 

To accelerate and improve the efficiency of vapor intrusion assessments, a leading approach is to employ field instruments that can analyze samples of soil vapor and indoor air in real time as opposed to waiting for laboratory results. The Interstate Technology Regulatory Council (ITRC) recently published a Fact Sheet on the use of real-time monitoring for vapor intrusion assessment. [6] Real-time sample analysis supports adaptive, high-confidence investigations, whereby the initial results guide investigators, while they are still in the field, on where to collect supplemental samples to address questions that arise from the initial results. Near-continuous, real-time analysis at stationary locations over a day or more can reveal underlying variability in VOC concentrations.

Rapid on-site testing also allows for the analysis of many more samples, more than 100 per day depending on the instrument, at lower cost per sample than conventional laboratory analysis. Lots of quick, inexpensive data offers opportunities to identify patterns and variability in the results, which are likely to lead to faster insights into the sources and pathways of the vapor intrusion risk and inform potential mitigation solutions. Real-time analysis can also help identify indoor sources of VOCs by allowing for targeted sampling near suspected indoor sources, as well as facilitate more sophisticated investigation methods, such as building pressure cycling to distinguish vapor intrusion from indoor sources of VOCs. [7] 

Instruments and analyzers capable of providing real-time results range from total VOC analyzers, such as hand-held photoionization detectors (PIDs), to equipment capable of analyzing and reporting individual VOCs, such as portable gas chromatographs (GCs), which are often coupled with various detectors or mass spectrometers (MS). This equipment is available for rental or purchase from manufacturers or vendors of environmental instruments. Figure 2 shows some examples of real-time analyzers deployed in the field.

The accuracy and detection limits of field analyzers for individual VOCs continues to improve, which is important because certain VOCs, such as PCE and TCE, have very low indoor air screening level concentrations established by U.S. EPA and most states. The instruments are sufficiently rugged so that they can be moved between sampling locations by hand or on a cart. Alternatively, the instruments can be set up in a stationary location in the field and the samples brought to the instrument for analysis using a sampling syringe or sampling bag.

Overcoming Limitations

Purchasing or renting field instruments for vapor intrusion assessment is typically a cost adder to the conventional approach of collecting samples and sending them to a laboratory for analysis. However, the cost per sample decreases with every sample analyzed using real-time instruments; thus, the overall cost of the investigation is likely to be lower as a result of obtaining more data in a single field event, and by reducing or eliminating the need for multiple field campaigns to obtain sufficient data to appropriately evaluate the risk. A recent vapor intrusion assessment of a 10,000-square-foot industrial building using real-time analysis was completed at about a third of the cost of the conventional approach. The cost savings were achieved by completing the real-time investigation in one mobilization as compared to the conventional approach, which would likely have required three or more sampling events to identify the vapor intrusion pathway.

Another potential limitation is that field instruments can be susceptible to loss of accuracy or malfunction that is difficult to diagnose and trouble-shoot without specific expertise. To ensure consistent data quality, real-time analysis should include calibration checks at the beginning and end of each day at least, or after obtaining a high-level reading. This requires having a gas standard on hand with a known VOC concentration to test the accuracy of the instrument within the concentration range of interest. 

Real-time analysis of soil vapor and indoor air samples using field instruments may be considered by regulators to be “screening” data that does not completely replace conventional sampling for vapor intrusion and other environmental investigations. Nevertheless, most regulators have embraced real-time vapor intrusion assessments because of how quickly health risks can be evaluated and mitigated if warranted. Even though conventional laboratory sample results are still likely to be required by regulators to support final decisions and approvals, the number of such samples and associated costs can be drastically reduced by doing most of the investigation using real-time analysis. 

Closing

Like investigations of soil or groundwater contamination, vapor intrusion assessments can potentially prolong schedules for mitigation and reuse of contaminated properties. Fast-track assessment using real-time analytical instruments is a way to streamline vapor intrusion investigations as compared to conventional approaches that rely on collecting samples, oftentimes over multiple site visits, for laboratory analysis. Limitations of real-time analysis include the cost and reliability of using field instruments, but these are typically outweighed by rapid, higher resolution assessments that can lead to lower overall investigation costs.

References

[1] U.S. EPA, OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air, June, 2015.

[2] Eklund, B. et al., Overview of State Approaches to Vapor Intrusion: 2023 Update, Groundwater Monitoring & Remediation, February 7, 2024.

[3] ASTM E1527-21, Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process, December 21, 2021.

[4] ASTM E2600-22, Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions, May 18, 2022.

[5] Holton C. et al., Temporal Variability of Indoor Air Concentrations under Natural Conditions in a House Overlying a Dilute Chlorinated Solvent Groundwater Plume, Environmental Science & Technology, Vol. 47(23), 2013.

[6] ITRC Vapor Intrusion Toolkit, Real-Time Monitoring Fact Sheet, January 2026.

https://itrcweb.org/vapor-intrusion-toolkit. 

[7] Guo, Y. et al., Development and Validation of a Controlled Pressure Method Test Protocol for Vapor Intrusion Pathway Assessment, Environmental Science & Technology, Vol. 54(12), 2020.

The Author:

David Shea, P.E. is a Senior Vice President at Sanborn, Head & Associates, Inc. based in Bedford, NH, where he has led vapor intrusion assessments and mitigation for commercial, industrial, and residential buildings for more than 25 years.

by Prateek Tare, Co-Founder & Executive Vice President, Distributed Energy Infrastructure 

The business case for brownfield solar redevelopment is well-established: idle contaminated land, ITC benefits, and, in several Northeast states, a state policy environment that actively incentivises putting solar on sites nobody else wants. 

What gets discussed less is what it actually takes to navigate the regulatory gauntlet between a viable site and a permitted, constructed project. Having recently completed a 4.9 MW AC solar and battery storage installation on a former W.R. Grace Superfund site in Acton, Massachusetts, I want to offer a frank account of what that process looked like, and what we learned from it.

Six Regulators, One Project

A standard distributed solar project already requires a long, multilevel permitting process. On brownfield sites, that complexity is squared. For a Superfund site like Acton, the process involved half a dozen distinct regulatory stakeholders:

●      The E.P.A.

●      The Massachusetts Department of Environmental Protection 

●      The Acton Planning Board & Building Department

●      The Board of Health

●      The Conservation Commission

●      W.R. Grace, the landowner, which operates an adjacent active facility

None of these stakeholders, or their demands, are unreasonable. Each has a legitimate interest in ensuring that solar construction on a capped contamination site doesn't disturb what was carefully contained. 

But half a dozen approval processes from different federal, state, local, and private agencies did mean that their requirements didn’t always align, their review cycles didn't coordinate, and my EPC team was the one entity responsible for synthesizing all of them into a single coherent plan.

The result of that synthesis was a project-specific site health, safety, and quality management plan that addressed all agencies' requirements in a single document. Getting that document approved — before any construction activity could begin — took roughly twice as long as pre-construction permitting on a comparable greenfield project. We recommend that any developer or financier evaluating a brownfield (especially a Superfund) site factor that extended timeline into their schedule from day one.

Regulatory Inertia: When Managing Asbestos Is Faster than Documenting It

One of the more frustrating realities of multi-agency brownfield permitting is that the pace of review is largely outside anyone's control. Each agency manages many obligations with limited bandwidth, and may end up reviewing a particular submission once a week. A question comes back; you answer it; you wait another week. Multiply that across six agencies, and even a well-prepared response to an unexpected finding can consume months.

We encountered this during Acton’s construction, when the team found asbestos approximately two inches below the surface in one area of the site. The affected zone was small, roughly a 10-by-30-foot rectangle. Developing and securing approval for the remediation plan took 8 months, from discovery in November 2024 to approval in May 2025.

The actual remediation work, once approved, took 2.5 days. 

That ratio isn’t an anomaly on Superfund sites; it’s just the nature of building on formerly hazardous land. Understanding this from the beginning, rather than treating it as a problem to be solved, enables a project team to plan around longer review times effectively.

Contingency Planning as Regulatory Strategy

The way to manage regulatory inertia is not to try to speed it up; it’s to anticipate it. On Acton, we’d already developed contingency protocols before breaking ground for a range of scenarios, including: 

●      Encountering contaminated soil

●      Finding asbestos

●      Monitored air quality exceeding safety thresholds

These plans were pre-submitted and pre-approved. So when the asbestos was found, we weren’t starting a regulatory process from scratch; we were activating a plan that already existed in the agencies' files.

Our preplanned approach also allowed construction in other areas of the site to continue safely in parallel, while the asbestos remediation plan worked through the approval process. So we didn’t have to wait eight months to make progress on the site; the delay was contained to a single zone rather than stopping the project entirely. 

The same logic applies to the day-to-day construction activity on a capped site. Environmental scientists were on site continuously during any soil disturbance work, with authority to stop activity immediately if monitoring thresholds were triggered. Having that protocol embedded in the approved health and safety plan — rather than improvised in the field — is what kept the project in good standing with every agency throughout construction.

When the EPC Gets Involved: the Earlier, the Better

On Acton, my EPC team came in when the developer, Syncarpha Capital, had completed about 80% of the site's permitting. That was the right moment to add EPC-specific construction expertise to the remaining approvals, as we were able to shape several conditions to make construction more efficient. 

On a standard project, design flexibility late in development is a minor inconvenience. On a Superfund site, it can be a significant cost driver. Road routing, equipment placement, foundation system selection, and electrical infrastructure pathways all have environmental implications that agencies will scrutinize, and changes to approved plans require the same multi-agency review cycle as the original submission. 

Getting EPC input earlier in the development process, before permitting locks in specific construction approaches, produces better projects and fewer costly mid-course corrections.

Engineering Decisions Are Regulatory Decisions

One thing that becomes clear quickly on contaminated sites is that engineering and regulatory strategy are inseparable. Every design choice has a regulatory implication, and the agencies are paying attention to the details. 

On Acton, our decision to use helical screw foundations (rather than traditional driven piles) allowed us to explain to regulators how each foundation penetration would minimize dust exposure, limit disturbance to the immediate zone, and leave no open bore. The decision to route all electrical infrastructure above grade was also a regulatory argument as much as an engineering one: no trenching, no soil exposure, no unknown material encountered.

Presenting these choices clearly and proactively, rather than waiting for agencies to ask questions, significantly accelerated review. Regulators are more confident in approving plans that show the developer has already thought through their concerns, than plans that require back-and-forth to address those issues.

A Replicable Model and Growing Opportunity

The Acton project interconnected with Eversource in summer 2025, in budget and on schedule. The town of Acton now collects property tax revenue from a parcel that was previously a net liability. W.R. Grace receives lease income. The project is being featured in an EPA newsletter as a replicable model for Superfund solar development — which, practically speaking, means this regulatory approach is one EPA considers worth repeating.

There’s no shortage of similar sites across the Northeast. While the regulatory complexity is real, it’s also navigable. The projects that succeed aren’t the ones that find ways around the process — they’re the ones that treat regulatory engagement as a core competency, plan for what they cannot predict, and get the right expertise involved before decisions get locked in.

The Author:

Prateek Tare is Co-Founder of Distributed Energy Infrastructure LLC (DEI), an EPC firm specializing in utility-scale solar, battery storage, agrivoltaics, and brownfield redevelopment. DEI's founders have collectively completed 50+ brownfield solar projects across the U.S.

Derek A. Pizarro¹ , Thomas P. McCullough² , Gary J. Meyer²

1. INTRODUCTION

The introduction of reactive iron species for treatment of inorganic contaminants is well known, yet the efficiencies of these various irons – zero valent iron (ZVI), ferrous or ferric sulfate, and iron sulfides, differ greatly in reactivity, efficiency, and cost. One group of reactive iron species are “reactive iron sulfides” which have been successfully used for the reduction and precipitation of inorganic contaminants such as chromium, arsenic, and mercury. 

This memorandum focuses on the use of a particular subset of reactive iron sulfides - mackinawite structured iron sulfide and sulfonated iron-aluminum layered double hydroxide (LDH), collectively referred in this paper as “FeS”. 

Another standalone reductant the environmental remediation industry has long studied and recognized for its usefulness is ZVI. However, ZVI may have its own set of constraints, limitations, and variabilities in successfully meeting remediation goals when deployed at a particular site. In addition, compared with these forms of FeS, ZVI is less chemically efficient (due to passivation) and persistent in the environment than other FeS. 

These constraints, limitations, and variability in success when using ZVI are related to many factors, including but not limited to: 

• The iron source used to manufacture the ZVI itself
• Particle sizing of the ZVI
• Low reactivity due to its intrinsic passive layer
• Narrow working pH
• Reactivity loss with time due to the precipitation of metal hydroxides and metal carbonates
• Low selectivity for target contaminants (especially under oxic conditions)
• Limited efficacy for treatment of some refractory contaminants
• Passivity of ZVI arising from certain contaminants
• Geochemical variability between sites and even within sites location (Guan, 2015).

To counteract some of these challenges, during the past decade, ZVI reagent providers have begun to sulfidate (sulfonate) their ZVI, chiefly with the intent is to increase the ZVI’s reactivity, selectivity, and longevity for various reductive processes. Although these sulfidated or sulfonated ZVIs (S-ZVI) have become a more commonly used product for both inorganic and organic contaminant reduction applications, consistently meeting a site’s long-term remediation goals has remained elusive.   

2. FERROUS SULFIDE CREATION 

Multiple university and industry research papers have proven that FeS can be generated abiotically (chemically) or biotically (biogeochemically) (Wang et al., 2024, Mangayayam et al., 2019).  While the formation of a stable, highly reactive FeS is possible in both abiotic and biotic scenarios, there are significant performance differences between chemically synthesized FeS (abiotic FeS) and biogeochemical generated FeS (biotic FeS)

Biogeochemically generating ferrous sulfides in-situ for site remediation has become a more prevalent practice in the past decade and a half, primarily based upon the research and evaluation of sulfate-rich aquifers with sulfate-reducing microbes that produced free sulfide (Rickard 2012 and Picard et al., 2018). The introduction of an iron component for oxidation and reaction with this free sulfide produced in these environments completed the FeS formation process. It is interesting to note that this concept traces its roots back to paleo-geochemical environments where biotic FeS was generated in low-temperature, anoxic surface water and groundwater settings by sulfate reducing microorganisms (SRM) (Wacey et al., 2015). In both settings, sulfate is utilized as an electron acceptor by indigenous or imported facultative microbes that produce (hydrogen) sulfide. This reductive metabolic process is known as biosulfidogenesis (Jameson et al., 2010).

This concept of biologically produced sulfide combined with an iron source has evolved over the years into the practice of mixing S-ZVI with microbes to jumpstart this process or provide the necessary components to facilitate the reaction and precipitation of iron sulfides, most notably for reductive dechlorination applications.  

More recently, it has become common for environmental practitioners to optimize this biotic formation of FeS by adding additional nutrients and kinetic additives to condition the aquifer and promote more optimal geochemical conditions that improve the speed, efficiency, and quantity of FeS produced biogeochemically. This combined injectate has been referred to as S-ZVI and enhanced reductive dechlorination (ERD), (SZVI+ERD), S-ZVI and enhanced in situ bioremediation (EISB) (S-ZVI+EISB), or S-ZVI and anaerobic bioremediation (AB), (S-ZVI+AB). 

Even with these advancements mentioned, one of the greatest challenges to overcome in these types of biogeochemical systems is the amount of time (and timing) required to create the desired environment for successful remediation. 

Many chemical and biological processes must occur concurrently and sequentially over a period of months to generate the quantity and type of FeS required. Some of these processes include the transformation and maintenance of the aquifer into a sulfate-reducing environment depleted of dissolved oxygen to promote biosulfidogenesis. This biosulfidogenesis must be coupled with oxidation of the iron source (e.g., ZVI) to produce several iron oxide species plus ferrous iron, and all these processes must be present and maintained for direct microbial interaction and formation of FeS. Additionally, the availability of sulfate (total or mass flux) also has a direct bearing on the formative size, iron morphology, and mineralogy of the iron sulfide; again, influencing the reactivity and mass of FeS generated. 

While earlier laboratory studies (Rickard, 1969) inferred that biotic FeS did not physically differ from abiotic FeS, more recent research suggests that this is not necessarily the case. Over the past five decades, more sophisticated laboratory experiments confirmed the issues with verifying the viability of usable biotic FeS and have found that non-reactive species of FeS may be generated (e.g., pyrite, greigite) and not the quantities of the reactive FeS desired. 

Using modern laboratory technologies, the physical and chemical characteristics (i.e. crystal size, morphology, texture, solubility) of the minerals formed in the presence of sulfate-reducing microorganisms (SRM) “have not been thoroughly investigated” and were “likely limited by the technology available at time” (Picard et al., 2018). Further, several factors influencing the ability of SRM to biotically form reactive FeS were highly affected by the geochemical setting- mainly influenced by the geological environment and anoxic conditions. Thus, the generation (derivation) and reactivity/utilization (consequence) of these biotic compounds can be more readily predicted in modern experiments where instrumentation is more appropriate for in-depth analysis, but also the equipment can control environmentally germane factors that play a role(s) in biotic FeS formation. 

3. STRUCTURAL DIFFERENCES

Iron sulfide mineralization experiments examining the influences of several biogenic parameters on the formation of biotic FeS after one week of incubation and then monthly for one year revealed significant structural differences. These biotically formed FeS particles were compared to abiotically prepared FeS at the same Fe:S ratios (Picard et al., 2016).  

Scanning Electron Microscope (SEM) images of biotic (upper row) and abiotic (lower row) iron sulfide precipitates, washed and air-dried in an anaerobic chamber, after one week of incubation.  (from Picard et al., 2018)

The Picard, et al., 2018 team concluded the following: 

1. Despite having similar Fe:S ratios and formed at similar pH, the mineral precipitates formed under biotic and abiotic experiments had visually distinct bulk morphologies.
2. Biotic precipitates appeared less opaque (i.e. absorbed less light) than abiotic precipitates.
3. After the minerals settled back to the bottom of the vials, the precipitates formed in biotic Fe experiments formed a sticky aggregate, while abiotic precipitates appeared finer and more homogeneously distributed. 
4. Precipitates in the biotic treatments aggregated more than the abiotic precipitates and thus formed larger particles. Aggregates of biotic particles in solution were much larger (1354 ± 120 nm) than abiotic aggregates (428 ± 148 nm). 
5. The massive aggregation of biogenic iron sulfide minerals is consistent with observations of ‘sticky’ mineral precipitates in the serum vials. 
6. The binding of Fe2+ to microbial compounds before the precipitation of FeS seems to play an important role in determining the final properties and morphology of iron sulfide minerals.
7. Different mineral morphologies are observed when minerals precipitate in the presence of dead SRM.

Overall, the application and applicability of these “controlled” laboratory experiments to actual remediation applications assumes the ability to efficiently create biotic FeS in an “uncontrolled” environment.  This means that: 

• Since the increased surface area (smaller sized particles) and uniformity within the structure has a direct impact on reactivity in-situ, and
• The distribution and reactivity of the biotically formed FeS in-situ is hampered by agglomeration and massing, abiotically formed FeS would be favored.

4. IMMEDIATE REMEDIATION

Deploying an abiotically, manufactured (chemically synthesized) FeS presents several advantages and resolutions to the limitations of the biogeochemically generated version. An FeS synthesized with an excess of sulfide (S-FeS) exhibits a larger interlayer spacing and unit cell volume that contains an interlayer of polysulfides which is structured is a wave pattern that has a greater surface area for contaminant reduction, degradation, and/or removal (Wang, et al., 2024). 

• Abiotically produced FeS (e.g., S-FeS) is not dependent on biogeochemical processes.
• Pyrite and greigite are not formed or introduced to the system, a conversion process which depletes the reductive setting.
• Phosphate in the geochemical setting does not retard or inhibit the formation of these types of abiotically produced FeS (or S-FeS) – the phosphate mineral complex (vivanite) is not a chemically available form of FeS.
• Extracellular materials, byproducts of microbial respiration, do not aggregate and produce irregular or outsized FeS particles.
• Agglomerated FeS particles are not present, which may reduce aquifer porosity.
• Multi-metal contaminants, or commingled inorganic and organic contaminants, settings do not shift the production or reactivity of the abiotically produced FeS which may occur during biotic FeS formation.

5. CONCLUSIONS

Biogeochemically generated FeS has gained acceptance in the environmental remediation industry for groundwater remediation of inorganic and organic contaminants. The introduction of bioremediation components with S-ZVI to generate FeS in situ is a demonstrated technology. A chemically manufactured version (S-FeS) has also been utilized with prevalence in recent years in similar deployments. It has proven to be effective immediately and demonstrate subsurface persistence. 

The differences in these two FeS materials, outside of performance and timeframe, are also realized in project cost and timeline. The intent of proponents of biotic FeS is to reduce the cost of the injectate on a per pound basis. Yet, because of many in situ factors, it is difficult to estimate the total mass of FeS that will be generated, even if conditions remain constant and optimal, which is difficult to control longer than weeks or months in most cases. The agglomerate structure is also not conducive to high-capacity reduction or degradation. With S-FeS, the weight of available irons and sulfides is straightforward to calculate and evaluate on a stoichiometric and cost basis. 

References

Guan X, Sun Y, Qin H, Li J, Lo IM, He D, Dong H. The limitations of applying zero-valent iron technology in contaminants sequestration and the corresponding countermeasures: the development in zero-valent iron technology in the last two decades (1994-2014). Water Res. 2015 May 15; 75:224-48. Epub 2015 Feb 28. 

Jameson, E., O.F. Rowe, K.B. Hallberg, and D.B. Johnson. Sulfidogenesis and selective precipitation of metals at low pH mediated by Acidithiobacillus spp. and acidophilic sulfate-reducing bacteria. Hydrometallurgy, Volume 104, Issues 3–4, 2010, Pages 488-493.

Mangayayam, M., J.P.H. Perez, K. Dideriksen, H. Freeman, N. Bovet, L.G. Benning, and D. Tobler. 2019. Structural transformation of sulfidated zero valent iron and its impact on long-term reactivity. Environmental Science. Nano. (00):1-9. 

Picard, Aude, Amy Gartman, and Peter R. Girguis. "What do we really know about the role of microorganisms in iron sulfide mineral formation?" Frontiers in Earth Science 4 (2016): 68.

Picard, Aude, Amy Gartman, David R. Clarke, Peter R. Girguis. Sulfate-reducing bacteria influence the nucleation and growth of mackinawite and greigite. Geochimica et Cosmochimica Acta, Volume 220, 2018, Pages 367-384.

Rickard, David. Chapter 8 - Microbial Sulfate Reduction in Sediments, Developments in Sedimentology, Elsevier, Volume 65, 2012, Pages 319-351.

Wacey, David, Matt R. Kilburn, Martin Saunders, John B. Cliff, Charlie Kong, Alexander G. Liu, Jack J. Matthews, and Martin D. Brasier. "Uncovering framboidal pyrite biogenicity using nano-scale CNorg mapping." Geology 43, no. 1 (2015): 27-30.

Wang, Chunli, et al. A novel Iron Sulfide Phase with Remarkable Hydroxylradical Generation Capability for Contaminants Degradation. Water Research 251 (2024): 121166.

Conflict of Interest Statement

Derek Pizarro declares no conflicts of interest. Thomas McCullough and Gary Meyer are the owners of Redox Solutions, LLC, which owns the intellectual property and manufacturing facility for a commercialized mackinawite structured iron product (FerroBlack®). 

¹AST Environmental, Inc. Freehold, New Jersey, USA.

²Redox Solutions, LLC. Carmel, Indiana, USA. 

The Author:

Derek Pizarro is a Senior Product Manager at AST Environmental, Inc. and a Certified Professional Geologist. He has 22 years of experience in environmental remediation, specifically contaminant transport studies, fractured bedrock characterization and injection, and reagent bench-scale testing and design for environmental sites and industrial process waste streams. Before joining AST, Derek was a Product Director and GM for an environmental chemical manufacturer, with previous experience in environmental consulting and bedrock services. He received a Bachelor of Science in Geology and Environmental Geosciences from Lafayette College. AST Environmental, Inc. (Freehold, NJ) is an internationally recognized leader in injection and environmental construction services, specifically known for groundwater remediation and in situ injection using proprietary subsurface distribution techniques. As a privately held small business, AST thrives as an integral, specialized part ofproject teams, focusing on supporting consultants, responsible parties, and stakeholders dealing with challenging environmental impacts in overburden, transition zones, and fractured bedrock. www.astenv.com

by Adam Henry, P.G., LEP, GZA GeoEnvironmental

On March 1, 2026, the Connecticut Transfer Act, which has been one of the primary drivers of environmental cleanup of polluted properties for more than 40 years, will sunset. After March 1, 2026, requirements for cleanups will no longer be triggered as a result of the transfer of an “establishment” and responsible parties will no longer be required to conduct site-wide investigations to “prove the negative.” However, responsible parties that already have Transfer Act obligations will still be required to complete them.

Starting March 1, 2026, the new Connecticut Release Based Cleanup Regulations (RBCRs) will require cleanup of pollution when it is discovered, similar to what is currently required in most other states. Discovery can occur when soil or groundwater samples collected March 1st or after identify pollution. Discovery can also occur when “multiple lines of evidence” are observed, including soil staining, odors, or urban fill material or information is available regarding historical testing data (however, a “filing cabinet exemption” exists for environmental reports/data issued prior to March 1, 2026).

When pollution is discovered, the RBCRs require the responsible party to complete cleanup of the polluted area within 120 days or report the pollution to the Connecticut Department of Energy and Environmental Protection (CTDEEP), or sooner if pollution is significant. If compliance with the RBCRs is not achieved within one year, the polluted area must be assigned to a “cleanup tier”, annual fees are required depending on the severity of the condition and deadlines for cleanup are applicable.

The transition from the Transfer Act, which regulates a relatively narrow subset of properties, to the RBCRs, which will apply to pollution discovered at all properties, represents a sea change in how environmental cleanups in Connecticut are completed and will have significant implications for how due diligence is conducted, construction projects are planned, and environmental information is managed.

The Author:

Adam Henry, P.G., LEP Mr. Henry, an Associate Principal of GZA GeoEnvironmental, Inc., leads the firm’s Buildings and Real Estate Development sector. He has over 20 years of experience managing site assessments, investigations, and remediation projects. He also works closely with lenders, developers, business owners and attorneys to complete their environmental due diligence during real estate acquisitions, divestiture and refinancing. If you have questions about how the new regulations may impact your business or property, please contact him at Adam.Henry@GZA.com or 860-858-3166.