groundwater protection

June 7, 2024

SAFE Act - CCS Legislation


On May 26, 2024, Illinois passed legislation aimed at regulating carbon capture and storage projects at the state level. The Safety and Aid for the Environment in Carbon Capture and Sequestration Act (SAFE CCS Act) has a broad scope, bipartisan support, and support from industry, environmental advocacy groups, and other Illinois stakeholder groups.

SCS Engineers believes the SAFE CCS Act will impact schedule, cost, and scope in Illinois’s permitting, operation, and post-closure phases of Class VI projects.

Please join long-time Illinois Deep Well Practitioners Stephanie Hill, Charles Hostetler, and Kacey Garber for a look at how SCS will apply our state-level experience to help Project Developers, Owners, and Operators focus their permitting, operational, and reporting practices to navigate these complexities and minimize Class VI project risk.


Watch the free, educational video Illinois 2024 Safety and Aid for the Environment in Carbon Capture and Sequestration Act – Safe CCS Act – how industries can provide Safe Act-compliant carbon capture and sequestration in the state.


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Posted by Diane Samuels at 1:21 pm

April 29, 2024

gwpc; supercritical carbon dioxide stream

Understanding the leaching behaviors of Appendix III and IV constituents from Coal Combustion Residuals (CCR) units as a function of time is an important aspect of remedy selection and corrective action design. This is particularly important in regulated or legacy units where CCR removal is not feasible, and infiltration or intermittent groundwater contact with CCR has the potential to mobilize constituents into the groundwater system.

It is well known that not all of the total mass of solid-phase constituents can be mobilized into the groundwater system. The leachable fraction of a constituent is the ratio between the amount that can be mobilized and the total amount in the solid phase assemblage. The leachable fraction is a function of the composition of the solid phase assemblage and the composition of infiltrating water.

In this study, Charles Hostetler, Ph.D., Kacey Garber, M.S., and Lindsey Hawksworth examine different methods that have been used to determine the leachable fraction of constituents from CCR and their strengths and weaknesses. We also examine various attempts to mechanistically interpret leachable fraction in terms of the composition of the stable phase assemblage and geochemical speciation, solubility, and adsorption reactions. Finally, we examine the consequences of uncertainty in leachable fractions on remedy selection and corrective action design.


Join SCS Engineers to attend this presentation on Mitigating CCR Leaching Behaviors and more at World of Coal Ash, May 13 – 16, 2024.




Posted by Diane Samuels at 6:00 am

February 5, 2024

gwpc; supercritical carbon dioxide stream

Featured speaker at the Groundwater Protection Council 2024 UIC Conference

Dr. Charles Hostetler is presenting on Wednesday, February 28th (11:00 am – 11:30 am, Century).

“Pore Space Conflicts: Class VI Injection into Previously Utilized Pore Space”
Class VI projects (involving underground injection control (UIC) wells for the geologic sequestration of carbon dioxide) can have a surprisingly large footprint in terms of the lateral extent of pore space occupied by supercritical carbon dioxide as well as pressure increases in the injection zone. A limited amount of subsurface pore space is available in certain economically important sedimentary basins and there can be difficulties in finding unutilized pore space.

Interactions among neighboring UIC projects can be an important consideration in the scoping and design of Class VI projects. Class VI project design has largely focused on examining the extent of the subsurface supercritical carbon dioxide plume and ensuring access to and control over the pore space physically occupied by the plume. The pressure buildup during injection also influences subsurface pore space. The existence of pressure buildup from neighboring injection projects can be an important limitation in efficiently utilizing pore space resources across multiple projects.

In this study, we examine the factors that affect the injectability of a supercritical carbon dioxide stream near a preexisting Class I (liquid waste) UIC well. We consider the factors that influence the pressure distribution in the injection zone, such as the compressibility of water and supercritical carbon dioxide, the properties of the aquifer materials, and the geometry of the injection zone and injection wells. We conclude by summarizing the general factors that should be considered in project scoping and Area of Review delineation—additional authors: Kacey Garber and Lindsey Hawksworth, SCS Engineers.

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Posted by Diane Samuels at 6:00 am

November 2, 2023

groundwater protection during carbon dioxide injection
Site Characterization is the stringent process by which the EPA permits Class VI wells for carbon storage and sequestration, our protection for groundwater.


SCS Engineers explains how site characterization provides groundwater protection during carbon dioxide injection. Geologist Lindsey Hawksworth discusses the process by which the EPA permits Class VI wells for carbon storage and sequestration. She takes viewers through the steps of determining if a proposed project site has a suitable injection zone to receive carbon dioxide and a confining zone that prevents fluid movement out of the injection zone. Her guidance may help viewers determine if their Class VI wells operate as permitted. And, importantly, it helps detect risks that may lead to groundwater endangerment and potential reevaluation of the area of review where potential threats may exist. Spend 10 minutes with this sharp young professional!


Watch Groundwater Protection During Carbon Dioxide Injection


Lindsey HawksworthMeet Lindsey Hawksworth, an SCS Project Professional. Lindsey provides groundwater sampling and monitoring, permitting, and field services management for groundwater protection. If you want to work with smart people like Lindsey, visit SCS Engineers. Reach out to her at or on LinkedIn with comments and questions.

See the SCS Engineers’ library of Clean Air and Greenhouse Gas Reduction videos for more educational content from our professionals. Visit our Carbon Sequestration & Deep Well Injection site where you’ll find more information about how to permanently isolate fluids and gases in deep geologic formations to ensure these materials stay there and don’t impact useable resources or the environment.




Posted by Diane Samuels at 6:00 am

June 12, 2023

ground water protection


Dr. Hostetler will present “A Computational Modeling Approach to Critical Pressure Calculations for Class VI Area of Review Delineation” [Thursday, September 14, 10:30 – Noon, Session Class VI UIC] at the Groundwater Protection Council 2023 Annual Forum in Tampa.

Presentation Category:  Carbon Capture and Underground Storage

Subsurface pressure increases as supercritical carbon dioxide is injected into a deep saline reservoir beneath a confining zone.  If the pressure buildup is great enough, brine could be lifted upward from the injection zone through an inadequately plugged or abandoned well that penetrates the confining zone.  This could result in the endangerment of an underground source of drinking water (USDW).  A Class VI Injection Permit requires a delineation of the Area of Review (AoR). The AoR is the superposition of the area of the buoyant supercritical plume itself, together with the area over which the pressure front is large enough to potentially endanger a USDW through some conduit.  The USEPA Class VI Guidance offers several approaches to calculating critical pressure.  Some of these methods are based on concepts of changes in potential energy in artificial penetration and are very easy to implement.  Unfortunately, they are simplified models and are also very conservative.  The USEPA Guidance also allows for the computation of the critical pressure by computational modeling.  We present a computational modeling approach that is more mechanistic, explicitly addresses uncertainty, can be updated as additional testing and monitoring data become available, and provides a more authentic representation of the critical pressure and hence, the AoR.

Charles HostetlerDr. Hostetler has nearly four decades of experience as a geochemist and hydrogeologist. His expertise focuses on subsurface multiphase flow modeling, groundwater flow and transport modeling, and reactive solute transport modeling.  Dr. Hostetler is an SCS Engineer’s Deep Well Initiative and Class VI Permit Team member.  Charles Hostetler has a BS in Geosciences and a Ph.D. in Planetary Sciences from the University of Arizona.


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Posted by Diane Samuels at 12:03 pm

February 21, 2023

SCS Engineers
Environmental Consultant Michael Wright, SCS Engineers


SCS Engineers welcomes Michael Wright to the firm as Senior Project Manager in Environmental Services. Wright’s work takes underutilized or contaminated properties and returns them to productive use.

Wright comes to SCS as a licensed professional geologist, geophysicist, hydrogeologist, and licensed general contractor. He has more than 35 years of experience on national projects, including work for the Federal Department of Defense, Army Corps of Engineers, EPA, Forest Service, and Caltrans. His clients include those in commercial real estate, finance and manufacturing, and port authorities, including the Port of Los Angeles. Wright also has an extensive background in conducting environmental insurance claim investigations and providing litigation support.

Wright holds specialty certifications in OSHA Health and Safety, OSHA Hazard Recognition, and Constructions Quality Management for Contractors. Wright holds professional affiliations with the Bay Area Geophysical Society, Groundwater Resources Association, and National Ground Water Association.

Welcome to SCS, Michael!






Posted by Diane Samuels at 6:00 am

October 20, 2022

SCS Engineers Environmental Consulting and Contracting
Kacey Garber is a groundwater protection project manager involved in maintaining the safety of our planet’s water supply.


Kacey Garber wanted to be a storm chaser when she grew up, trained to detect and alert others of brewing severe weather. But then she found geology and went on to earn graduate and postgraduate degrees in this discipline, which brought the summa cum laude scholar to SCS Engineers. Her charge is groundwater protection, an area where she aspires to grow her expertise further.

The young professional (YP) is already moving quickly along that trajectory, beginning by supporting landfills and utilities and now applying her strong skill set in a highly specialized, fast-evolving arena – deep-well injection.

A common thread binds Garber’s main interests – groundwater protection, geology, and meteorology/trained weather spotter, which she still does in her spare time.

“What draws me to these niches is the thrill of being part of the scientific community collecting and interpreting compelling data to figure out solutions. And not just any solutions but those with the promise of helping protect people and the environment. That’s where I want to have an impact,” she says.

She’s heard of climate change almost her whole life and has thought for almost as long that someday she would play some problem-solving role to help mitigate its effects.

Garber splits her time at SCS between several areas. She monitors and tests groundwater for landfills, closely following both active and closed sites, and helping landfills prepare for post-closure. She supports electric utilities with groundwater issues potentially related to their closed coal ash ponds and disposal sites. And now, she is leading groundwater protection tasks for class VI deep-well injection projects as part of a dedicated team that permits and builds these wells.

The cutting-edge, EPA-regulated technology injects and stores carbon dioxide underground safely, preventing this potent greenhouse gas from releasing into the atmosphere.

Garber’s on-the-job experience in the field is paramount to her new, added role. Her studies in geology focused on sedimentary basins are also proving important.

“Sedimentary basins [where large bodies of rock occur] are ideal spots for carbon sequestration. But first, you must understand the geologic characteristics of the basin and each rock formation and determine exactly which locations within the basin are best for injecting and storing carbon dioxide. That’s a big part of what I do to ensure efficiency and safety,” she says.

In her eyes, Garber lives and works in the best of two worlds in that she can concentrate on different but related interests.

“Joining our deep-well injection team brings me back to my roots in traditional geology. But it also enables me to stay on the groundwater monitoring track, which is meaningful as I aim to position myself as a national expert who can do this important work. Ensuring water quality is critical to protecting the environment and communities, as a large part of our country relies on groundwater for its water supply.”

As she grows her reach into deep-well injection, she grows her relationships too. The multidisciplinary team—all new colleagues to her a year ago are her newest work family addition.

“It’s humbling to partner with so many incredibly smart people, each with their respective areas of expertise. We’ve come to trust each other’s judgment as we solve issues together. And as it turns out, we have a lot in common, especially our love of nature—the joy we find in being outdoors, camping, and hiking.”

Getting a foot in the door of a nationwide environmental firm has been good. Especially one that welcomes YPs and is vested in their career development, something she found uncommon among companies with as great a geographical reach and breadth of expertise.

She seized the opportunity.

“I saw it as a way to gain visibility early in my career. And to become well-rounded in my discipline. We perform groundwater monitoring for many project types, and there are parallels in how it’s done in each; I can support and learn from all of them.”

At the same time, she explores other specialized areas.

“There are designated experts here at SCS in many professions and industries dedicated to caring for the environment. They are great resources to learn from.”

Where she would land one day was unknown for a while. Garber thought she’d become a professor or researcher at one time. But that changed when she interned with the United States Geological Survey, venturing beyond the classroom and lab to assess land use impacts on water quality and floodplains.

“I liked solving problems out in the field and decided pretty quickly that’s where I wanted to be,” she says.

The desire to teach is still in her, though. She travels state to state, presenting to regulators, technology experts, and other seasoned professionals and decision-makers on groundwater modeling, monitoring, and testing.

She also reaches out to ambitious geology students, visiting them on campus to tell them about deep-well injection and carbon sequestration and that the company she works for does these projects around the country. Their curriculum rarely includes an introduction to this specialized niche.

Remembering herself as one of them, Garber says, “I didn’t know of this work in college. I first learned as a newcomer to SCS.

It intrigued me, and I was excited to hear that the deep-well injection group needed a team member with a strong monitoring background. Later I thought, how cool it would be for students to discover this potential career path early.”

How else does she fill her days? Besides watching for and reporting developing storms to weather bureaus– she called in a funnel cloud once out in the field—she plays guitar in a local band.

Sometimes she goes solo and has played and sung at a nearby rehabilitation center and nursing home.

“I love playing music. It makes me happy. But what really feels good is to play for folks, especially those who may be more limited in what they can do and where they can go. For them, listening to music and dancing seems to be the highlight of their day. It makes me happy to see them happy.”


SCS Engineers Environmental Consulting and Contracting
Kacey presenting at the 2022 Groundwater Protection Council’s Annual Conference.
SCS Engineers Environmental Consulting and Contracting
Geoscientists love their rocks! Kacey hiking Mt. Lemmon for the view and the geology.

Ensuring a safe, healthy environment and a better world for everyone is about a commitment to people, community, and hard work. Thank you, Kacey Garber, for your dedication to keeping our groundwater safe, for helping execute innovative solutions to advance sustainability, and for bringing a lift to others along the way. 


You, can make a difference in your life, your work, and your community!





Posted by Diane Samuels at 6:00 am

December 23, 2021

environmental consultants illinois

Charles Hostetler, Ph.D., and Kacey Garber join the award-winning SCS Engineers practice serving the region.


As more businesses and municipalities move toward sustainable practices to help protect natural resources, the environmental consulting and contracting firm SCS Engineers is experiencing exponential growth. Most recently, SCS welcomes two professional staff in Peoria, Illinois, with impressive groundwater and wetlands protection backgrounds.

Landfills are required to monitor the underlying groundwater for contamination during their active life and post-closure care period. They operate using modern engineering methods, liquids management systems, and technologies that meet or exceed state and federal compliance. Landfill development may impact existing wetlands or navigable waters of the United States; developing new water resources mitigates or offsets those impacts.

Dr. Charles Hostetler has over two decades of experience as a hydrogeologist planning and overseeing groundwater and wetlands protection programs. His field experience helps solid waste facilities site and run operations safely while proactively monitoring and protecting groundwater and wetland resources. His diverse experience includes developing conceptual designs for the treatment of PFAS in liquid waste streams and sequestration in landfills. You can learn more about Charles Hostetler here.

Ms. Kacey Garber comes to SCS as an experienced hydrogeologist specializing in solid waste management permitting and groundwater monitoring well design and construction projects. Her areas of expertise include groundwater and wetlands monitoring, environmental sampling, hydrogeological site characterizations, groundwater monitoring well design, monitoring well installation oversight, and designing special groundwater studies. You can learn more about Kacey Garber here.

SCS Engineers Business Unit Director Eric Nelson says,

Charles Hostetler, Ph.D., and Kacey Garber bring their landfill permitting and groundwater management expertise to our environmental practice in Illinois. Charles and Kacey share their expertise on the emerging PFAS regulations applied to landfills with our industry at SWANA and NWRA conferences. Garber brings hard-rock geology and groundwater expertise. Her project leadership has been instrumental in removing a Part 807 facility from Post-Closure Care requirements. Hostetler has the distinction of having removed the only Part 811 facility from a Post-Closure Case.

…and your new colleagues say WELCOME TO SCS!





Posted by Diane Samuels at 6:00 am

December 14, 2020

environmental compliance firm

SCS Engineers’ SCSeTools® platform and applications help facilities and companies operate more efficiently by continually gauging operational health and identify trends critical to operations and the environment.


SCS Technology Services®, the technology development practice within SCS Engineers, announces a new application for tracking and analyzing environmental data. The application expands the firm’s SCSeTools® platform, demonstrating its commitment to developing the most advanced data-driven technology in the environmental services industry.

Groundwater monitoring and compliance services are long-term and expensive responsibilities that generate enormous amounts of monitoring and laboratory data. SCS Groundwater™ is a tool to monitor and manage the data associated with operations and reporting requirements for various sites. Sites include active or closed landfills, plants, and impact sites such as former dry cleaners or industrial facilities.

The application also monitors and manages data effectively for clean groundwater applications such as groundwater basin management projects consistent with standard protocol under state and federal environmental compliance rules. SCS Groundwater™ collects and efficiently organizes groundwater monitoring and maintenance data providing those responsible for environmental compliance with a reliable, consistent, and cost-effective way to manage the large volume of information.

The application’s primary value is enabling users to set up a detailed monitoring plan for any number of events, including the sampling points to include and what analyses to perform at each point. Once the information upload is finished, the application checks incoming data against the plan to confirm all work is complete.

SCS Groundwater™ generates reporting components such as data tables, charts, graphs, and maps for compliance, reporting, and finding trends. For example, on a brownfield site, the compliance manager could upload historical monitoring data results, view the data trends over time, and then produce report tables and figures. Operators can also use the data in other applications for additional analysis or visualization.


SCS Engineers’ environmental solutions and technology directly result from our experience and dedication to industries responsible for safeguarding the environment as they deliver services and products. For information about SCS, visit the SCS eTools pages or enjoy our 50th Anniversary video to see the technology in action.

The SCSeTools® platform and applications help facilities operate more efficiently by continually gauging operational health and spot trends that help determine when and how to invest in infrastructure. Field staff, environmental compliance experts, brownfields, developers, and clients in the waste industry guide the technology designs. For additional information and demonstrations of these productivity-enhancing tools, please contact .





Posted by Diane Samuels at 6:00 am

January 6, 2020

Utilities face many challenges as they move forward developing programs to deal with disposal or recycling of coal combustion residuals (CCR). The U.S. Environmental Protection Agency (EPA) recently proposed changes to the 2015-enacted federal coal ash rule and issued a proposed Federal permitting program rule for CCR.

SCS Engineers closely follows developments relating to coal ash disposal. The company works with landfill operators, utilities, and others who deal with CCR to meet the challenges of proper waste management as federal, state, and local regulations evolve.

In addition to evaluating the impact of proposed rule changes and permitting programs, many utilities are currently working to address groundwater impacts from CCR units monitored under the current Federal CCR rules (40 CFR 257 Subpart D—Standards for the Disposal of Coal Combustion Residuals in Landfills and Surface Impoundments). Based on timing in the CCR rule, utilities have recently completed an Assessment of Corrective Measures (ACM) for groundwater impacts and are working on selecting a remedy for the groundwater impacts identified.

The remedies for CCR units not already closed include some form of source control, along with strategies to limit impacts to groundwater. The most prevalent remedies today include closure-in-place, or cap-in-place, of coal ash storage sites, or closure-by-removal, in which CCR is dewatered and excavated, then transported to a lined landfill.

So which factors should utilities consider as they evaluate different remedies?

“The answer to this question is wide and varied,” said Eric Nelson, a vice president with SCS. Nelson is one of the company’s national experts for electric utilities, and an experienced engineer and hydrogeologist. “In part, it depends on the situation” Nelson noted that remedies for disposal of waste such as CCR from power plants could differ from the disposal of municipal solid waste (MSW) or everyday trash.

“Is the landfill or impoundment already closed or capped, is it active or inactive, what type of CCR or waste (is being disposed of)?” Nelson said. “Then there’s the physical setting, the geology, the receptors or lack of receptors. My opinion is that the industry is in a tough spot because the remedy selection process is strongly influenced by opinion and widely varied regulatory climates.”

“For instance, selecting a remedy, which in many cases will include closing a surface impoundment, that leaves CCR in place feels risky to some due to what is happening in places like the Carolinas and Virginia,” Nelson said. “Anything short of exhumation and re-disposal seems to be cast as insufficient by some when closure in place is a tested and proven response in other arenas [such as MSW]. A one-size-fits-all solution isn’t appropriate.”

Some utilities have moved forward with complete excavation, removing ash, and re-disposing it in a lined landfill. Some of these projects have likely been influenced by local efforts to dictate the remedy selection process through negotiation or legislation. The fact that some utilities have selected closure-by-removal does not mean this remedy is suitable in all situations.

Sherren Clark, vice president and Solid Waste Services Division leader for the Upper Midwest Region of SCS, said: “In terms of remedy selection, one key difference between MSW and CCR sites has been that for CCR sites, total CCR removal is an option that has been put on the table, and is being implemented at some sites, both small and large. For MSW, total waste removal has very rarely been the chosen approach and has typically been thought of as infeasible unless there were other financial drivers supporting that choice. The typical approaches for MSW sites have focused on source control options, such as an improved cap or enhanced landfill gas collection systems.”

Nelson said that engineers working on plans for CCR disposal could look at what’s been done at MSW sites.

“We might discuss the various approaches to corrective action that are described in some early guidance for MSW work,” Nelson said, pointing to EPA Technical Manual EPA530-R-93-017, which deals with solid waste disposal facility criteria and addresses active remediation, plume containment, and source control. “I believe there are significant guidance and experience we can draw from the MSW arena on the different remedies and how to evaluate them.”

Nelson said that “potential remedies must be evaluated according to the requirements in 40 CFR 257.96 and 257.97,” which are EPA rules outlined in the Electronic Code of Federal Regulations (e-CFR). Part 257 details Criteria for Classification of Solid Waste Disposal Facilities and Practices, including Subpart D-Standards for the Disposal of Coal Combustion Residuals in Landfills and Surface Impoundments, including groundwater monitoring and corrective action. Section 257.96 deals with ACMs. Nelson notes an important distinction with this approach: “One important note is that cost cannot be considered as it is in the similar rules for MSW.”

Jennifer Robb, vice president and project director with SCS’s Solid Waste Services Division in Reston, Virginia, said programs for the disposal of MSW “are pretty much identical to the process a [CCR] site has to go through. The only difference is the constituents they sample the groundwater for. The CCR sites, they’re going to have an issue with metals. The big problem with that is, a lot of the metals are naturally occurring.”

Robb noted that’s where the alternate source demonstration (ASD) comes in, to determine the source of contaminants, and whether a CCR pond or other ash storage facility is responsible for causing levels of contaminants to excess groundwater protection standards.

Evolving Regulatory Landscape

The Environmental Protection Agency (EPA) is proposing a streamlined, efficient federal permitting program for the disposal of coal combustion residuals (CCR) in surface impoundments and landfills, which includes electronic permitting. The new rules are designed to offer utilities more flexibility and provide regulatory clarity.

(1) In August 2019, EPA proposed amendments to CCR regulations that encourage appropriate beneficial re-use and clarity on managing coal ash piles. The proposal would also enhance transparency by making facility information more readily available to the public.

(2) A November 4, 2019, proposal establishes August 2020 as the date for utilities to stop receipt of waste in affected impoundments. It gives utilities the ability to demonstrate the need to develop new, environmentally protective waste disposal technology subject to EPA approval.

(3) On December 19, 2019, EPA proposed a federal permitting program for coal ash disposal units. The proposal includes requirements for federal CCR permit applications, content, and modification, as well as procedural requirements. EPA would implement the permit program at CCR units in states that have not submitted their own CCR permit program for approval. EPA already accepted and approved state permitting programs in Oklahoma and Georgia and is working with others to develop their programs. On December 16, 2019, the EPA Administrator signed a Federal Register notice approving Georgia’s state permit program for the management of CCR.

The November proposal addresses the deadline to stop accepting waste for unlined surface impoundments managing coal ash. It includes a new date of August 31, 2020, for facilities to stop placing waste into these units and either retrofit them or begin closure. The proposal would allow certain facilities additional time to develop an alternate capacity to manage their waste streams before initiating closure of surface impoundments. It would also re-classify clay-lined surface impoundments from “lined” to “unlined,” which means that clay-lined impoundments would have to be retrofitted or closed. Under the proposal, all unlined units would have to be retrofitted or close, not just those that detect groundwater contamination above regulatory levels.

The 60-day comment period on the November proposal closes January 31, 2020. The EPA will conduct a virtual public hearing about the proposed rule on January 7, 2020, at 9 a.m. Eastern Time. Register for the meeting to learn more. A 60-day comment period for the proposed federal permitting program will begin once the rule is published in the Federal Register.

This blog series highlighting the experience and expertise of SCS Engineers staff will continue with a look at examples of remedies for coal ash disposal and storage. If you have questions, contact the authors by selecting one of their names, or email us at .






Posted by Diane Samuels at 6:04 am