SCS Engineers shows you in this short video featuring SCS Remote Monitoring & Control technology built for landfill owners and operators, solar farms, and for use on pipelines by SCS Engineers, landfill and environmental practitioners.
Introduction
Contamination at thousands of shopping centers across California from previous business operations presents problems for property owners who wish to continue commercial use, redevelop, and maintain property value. Commercial property remediation targets returning these buildings and land to predevelopment conditions, presenting opportunities for reuse and redevelopment.
One property owner discovered that securing adequate funding and working closely with state and regional regulatory agencies leads to success despite changing regulations and oversimplifying regulatory health risk assessment methods. The Draft Cal-EPA Supplemental Vapor Intrusion Guidance (DSVIG) suggests changes to the methods in which vapor phase transport and potential health risks are modeled and calculated for occupants of buildings with known soil or groundwater contamination beneath them. These changes, the result of a multi-year working group collaboration, recommend an arguably more conservative calculation of indoor air quality. The changes rely on EPA work and guidance, with empirically derived attenuation factors (AFs), which will increase the number of sites requiring additional environmental assessment and mitigation to achieve health risk standards. Although the DSVIG is currently draft guidance, there is evidence that regional regulatory agencies have already adopted AFs in calculating indoor air quality.
Diamond Bar Commercial Center Assessment and Mitigation
Drucker Survivors Trust owns and operates a multi-tenant commercial building in Diamond Bar, California, including a dry cleaner at one time. The former cleaners caused an unauthorized release of dry cleaning solvent containing chlorinated volatile organic compounds to the subsurface during its operation.
Financing for this all too common situation requires environmental due diligence in the form of research commonly completed in a Phase I Environmental Site Assessment followed by an assessment to characterize potential liabilities associated with chlorinated solvent releases before lenders provide funding.
Regulatory oversight in California can either be voluntarily engaged or involuntarily if assessment activities on an adjacent or nearby property indicate the presence of chlorinated volatile organic compounds in the subsurface linked to dry cleaning operations in the vicinity.
The Drucker Survivors Trust sought approval from the applicable regulatory agency, Los Angeles Regional Water Quality Control Board (LARWQCB), to assess and mitigate the chlorinated solvent release to ensure the protection of human health and reduce environmental liabilities associated with the property.
Regulatory closure is the acceptance of assessment and remediation activities by the governing regulatory entity to bring the site into compliance. Compliance, in this case, required assessment and mitigation of beneficial use groundwater underlying the property impacted by the solvent release and completing soil vapor assessment and health risk screening calculations under current state and federal guidelines.
Guidance on vapor assessment and associated health risk screening methods have changed rapidly in California state environmental regulations. As environmental engineers and consultants, SCS professionals manage an extensive list of vapor assessment, health risk assessment, and vapor intrusion mitigation projects resolving these vapor–related issues.
To start this project, the SCS team prepared a successful grant application securing more than $650,000 in funding from the California State Water Resources Control Board’s Site Cleanup Subaccount Program (SB 445, established in 2014). This state-provided grant money enables the assessment and mitigation necessary to close with the LARWQCB.
Subsurface assessment activities defined the extent and scale of chlorinated solvent impacts to soil vapor, soil, and groundwater, enabling the design of a remediation program. To reduce the groundwater contamination to cleanup levels set by the LARWQCB, SCS Engineers designed and implemented an injection program to deliver engineered chemicals directly to the groundwater plume. The injected chemicals destroy the chlorinated solvents via in situ chemical reduction and stimulation of biological degradation.
While challenging drilling conditions precluded previous consultants from attempting groundwater remediation, SCS industry experts safely achieved up to a 99 percent concentration reduction within the groundwater plume. SCS designed a soil vapor assessment that relied more on site-specific data collection and less on conservative default assumptions while conforming to the most current regulatory guidance targeted at minimal impact on the building tenants.
SCS managed all aspects of the project, including grant requirements and communication between the client, regional and state water board staff, city staff, and subcontractors. Obtaining and managing entrance under state waste discharge requirements is necessary, and SCS completed all necessary permitting and reporting requirements to facilitate the groundwater mitigation activities. Careful planning and experience with similar projects minimized impacts on tenants and kept the project on a strict timeline with no missed regulatory deadlines. SCS continues working with the LARWQCB to conclude the client’s final closure requirements and is in the process of applying for an additional $900,000 in SCAP funding to implement the final stages of the project targeted at obtaining final regulatory closure.
Changes Coming to Regulatory Guidance
Recent changes to regulatory guidance in California are arguably making obtaining closure on sites with vapor intrusion health risk concerns more difficult to achieve. The Draft Cal-EPA Supplemental Vapor Intrusion Guidance (DSVIG) suggests changes to the methods in which vapor phase transport and potential health risks are modeled and calculated for occupants of buildings with known soil or groundwater contamination beneath them. These changes, which result from a multi-year working group collaboration, recommend a more extensive and site-specific data collection effort. They include indoor air quality calculation methods relying on EPA work and guidance and empirically derived attenuation factors (AFs) which some would argue lead to overestimating potential health risks.
The consequences of the DSVIG are potentially significant if adopted as is and appear likely to result in more sites being “screened in” with vapor intrusion issues and more sites requiring mitigation. The impact, resultant costs, and possibly detrimental secondary effects such as decreases in affordable housing production, particularly in urban infill areas. And while none would argue with appropriate protection of health risk, the question is whether the studies and empirical data used to support the DSVIG represents the best available science and is truly representative and predictive of risk.
The DSVIG adopts an attenuation rate of 0.03 for the flux of both soil and sub-slab vapor to indoor air based on a previous 2012 EPA Study comprised of empirical data collected from buildings arguably not representative of modern construction in California.
The development of a reliable screening level attenuation factor for California based on high-quality, recent, California-specific data:
1) Will be protective of human health, as no toxicological imperative or basis supports a call for accelerated or immediate action (as evidenced by the fact that the DSVIG workgroup commenced its work in 2014 and issued the review draft in 2020).
2) Will ensure California’s environmental policy satisfies the gold standard for data quality and insightful analysis in which the state once took pride.
3) Will not unnecessarily decimate the California housing development market. The empirically derived screening level AF in the DSVIG is overly conservative based on the available data. More accurate empirical data and measurement methods for site-specific measurement are available.
With respect, oversimplifying the VI health risk assessment methods has constrained the environmental community’s ability to apply science-based health risk screenings, often resulting in costs associated with additional environmental assessment and mitigation. An additional revision to the DSVIG to utilize a screening level AF more reflective of the current California data and building specifications could save state resources, increase infill development by reducing urban sprawl, promote housing development, all while protecting human health.
About the Author: Keith Etchells is a professional geologist and hydrogeologist with over two decades of experience assisting clients in managing environmental risks associated with ownership, transfer, or operation of commercial, industrial, and waste disposal properties. His particular technical expertise involves aspects of groundwater science and engineering relevant to contaminated sites and landfills, including supervision and conduct of subsurface data acquisition, remedial design and implementation, conceptual site model development, aquifer testing, extraction well design, groundwater quality evaluation and treatment, vapor intrusion health risk assessment and mitigation, predictive modeling, and contaminated soil and groundwater remediation design.
He is responsible for designing analytical, geotechnical, and hydrogeological data collection programs to complete subsurface assessment and remediation. He has prepared subsurface assessment documents, property mitigation plans, vapor intrusion risk assessment documents, soil management plans, aquifer characterization documents, conceptual site models, and groundwater remedial design and implementation documents.
Environmental industry leader
At SCS Engineers, we empower you with skills, experience, and energy to make a difference every day. As an employee-owned engineering consulting and contracting firm, we’re driven by a purpose to protect the air, water, and soil. We’ve been at the forefront of sustainable environmental solutions for more than 50 years.
Employee-owned
As an employee-owner, you help make our business better and build wealth for your retirement. Through our Employee Stock Ownership Plan (ESOP), you’ll gain a financial stake in the business without investing your own money. When the business performs well, so does the value of your shares.
Supporting your career growth
Continual learning and innovation are fundamental to our business. We support skill development, license, and professional certification. There’s always room to grow when you’re ready to take your career to the next level.
Recognized for excellence
Our professionals are on the front line delivering engineering services for public and private sector customers. We’ve built deep bench strength, and the company is continually ranked nationally as a research and technology innovation leader.
Exceptional benefits
In addition to our collaborative culture and employee ownership, we offer outstanding benefits to support our employees’ well-being, financial health, and wellness. Our Student Debt Employer Contribution benefit helps pay off college loans faster.
SCS Engineers is an EOE/V/D Employer
Become one of the engineers, consultants, scientists, and technicians that help private and public entities run cleaner and more efficiently. A very rewarding place to have a career!
SCS’s Mike Miller explains the impact of the new ASTM E1527-21 Due Diligence Standard. Mike covers the history, CERCLA, defenses, and the changes impacting due diligence in the new Standard in this video. Watch it here. Use chapters in the timeline to jump from topic to topic at these start points:
Learn more about Environmental Due Diligence and All Appropriate Inquiries, and meet Mike Miller, SCS’s National Expert. Today’s commercial real estate transactions must take environmental issues into consideration. Complex laws can impose significant environmental liabilities on purchasers, sellers, and lenders, whether or not they caused the problem, and whether or not they still own the property. Environmental Engineers can help protect you and your investment.
Recent changes to regulatory guidance in California are arguably making obtaining closure on sites with vapor intrusion health risk concerns more difficult to achieve. The Draft Cal-EPA Supplemental Vapor Intrusion Guidance (DSVIG) suggests changes to the methods in which vapor phase transport and potential health risks are modeled and calculated for occupants of buildings with known soil or groundwater contamination beneath them. These changes, which result from a multi-year working group collaboration, recommend a more extensive and site-specific data collection effort. They include indoor air quality calculation methods relying on EPA work and guidance and empirically derived attenuation factors (AFs) which some would argue lead to overestimating potential health risks.
The consequences of the DSVIG are potentially significant if adopted as is and appear likely to result in more sites being “screened in” with vapor intrusion issues and more sites requiring mitigation. The impact, resultant costs, and possibly detrimental secondary effects include decreases in affordable housing production, particularly in urban infill areas. And while none would argue with appropriate protection of health risk, the question is whether the studies and empirical data used to support the DSVIG represents the best available science and is truly representative and predictive of risk.
The DSVIG adopts an attenuation rate of 0.03 for the flux of both soil and sub-slab vapor to indoor air based on a previous 2012 EPA Study comprised of empirical data collected from buildings arguably not representative of modern construction in California. The development of a reliable screening level attenuation factor for California based on high-quality, recent, California-specific data:
1) Will be protective of human health, as no toxicological imperative or basis supports a call for accelerated or immediate action (as evidenced by the fact that the DSVIG workgroup commenced its work in 2014 and issued the review draft in 2020).
2) Will ensure California’s environmental policy satisfies the gold standard for data quality and insightful analysis in which the state once took pride.
3) Will not unnecessarily decimate the California housing development market. The empirically derived screening level AF in the DSVIG is overly conservative based on the available data. More accurate empirical data and measurement methods for site-specific measurement are available.
Oversimplifying the VI health risk assessment methods has constrained the environmental community’s ability to apply science-based health risk screenings, often resulting in costs associated with additional environmental assessment and mitigation. An additional revision to the DSVIG to utilize a screening level AF more reflective of the current California data and building specifications could save state resources, increase infill development by reducing urban sprawl, promote housing development, all while protecting human health.
Take a deeper dive into this topic in the Daily Transcript article Vapor intrusion rules hamper infill projects.
The Reno County Board of Commissioners approved contracting with SCS Engineers to support the County’s Solid Waste Department through 2024. SCS will provide environmental engineering, consulting, and field services for the Reno County Municipal Solid Waste Facilities for the next three years. The contract approval directly resulted from the firm’s experience, expertise, and long-standing relationship with Reno County.
SCS has a history of providing compliance, planning, and engineering services to Reno County. The firm helps the County continually comply with the Kansas Department of Health and Environment (KDHE) and other agency regulations. Compliance activities throughout the year include groundwater and leachate sampling, laboratory analyses, permit renewals, air permitting, and associated report preparation in accordance with Kansas Administrative Regulations.
Landfills contain complex systems to protect the health of nearby communities and the environment. The County uses SCS professionals’ expertise and proprietary software for air quality and gas collection and control systems (GCCS) operations, monitoring, and maintenance (OMM). Reno County relies on SCS to maintain these systems and keep them in compliance to focus on their other operations.
These preventative services keep the landfills fully compliant with state and federal regulatory requirements while aligned with the County’s system performance goals and anticipated operational and maintenance activities.
In 2021 the U.S. Environmental Protection Agency (EPA) changed legislation regulating landfills, specifically the New Source Performance Standards (NSPS) and other air quality regulations. These changes significantly increased the monitoring, record-keeping, data management, and reporting tasks for many landfills across the nation, including the Reno County Facility. SCS has helped Reno County navigate these changes and will continue to facilitate changes as the County looks to expand its landfill in the future. Combined with the supply chain and labor shortages, the Solid Waste Department is securing its essential services from disruptions.
Project Director Steve Linehan said, “SCS is privileged that Reno County entrusts us to partner with them to maintain the landfills’ safe and efficient operations. The Solid Waste Department supports the citizens and the environment; we’re honored to help.”
EPA Requires Reporting on Releases and Other Waste Management of Certain PFAS, Including PFBS
As part of EPA’s Strategic Roadmap, the Agency announced the automatic addition of four per- and polyfluoroalkyl substances (PFAS) to the Toxics Release Inventory (TRI) list.
As of January 1, 2022, facilities that are subject to reporting requirements for these chemicals should start tracking their activities involving these PFAS as required by Section 313 of the Emergency Planning and Community Right-to-Know Act. Reporting forms for these PFAS will be due to EPA by July 1, 2023, for the calendar year 2022 data.
In April 2021:
EPA previously updated the Code of Federal Regulations with PFAS that were added to the TRI on January 1, 2021, under section 7321(c) of the NDAA and regulated by an existing significant new use rule (SNUR) under the Toxic Substances Control Act (see 40 CFR 721.10536).
In addition to continuing to add PFAS to the TRI, the EPA will soon announce a series of PFAS test orders requiring PFAS manufacturers to provide the Agency with toxicity data and information on PFAS.
If you have questions or concerns about reporting requirements, contact one of our environmental chemistry – hazardous materials/waste professionals at .
An industry leader
At SCS Engineers, you’re empowered to use your skill, experience, and energy to make a difference every day. As an employee-owned engineering consulting and contracting firm, we’re driven by a purpose to protect the air, water, and soil. We’ve been at the forefront of sustainable environmental solutions for more than 50 years.
Employee-owned
As an employee-owner, you help to make our business better and build wealth for your retirement. Through our Employee Stock Ownership Plan (ESOP), you’ll gain a financial stake in the business without investing your own money. When the business performs well, so does the value of your shares.
Supporting your career growth
Continual learning and innovation are fundamental to our business. We support skill development, license, and professional certification. There’s always room to grow when you’re ready to take your career to the next level.
Recognized for excellence
Our professionals are on the front line delivering engineering services for public and private sector customers. We’ve built deep bench strength, and the company is continually ranked nationally as a research and technology innovation leader.
Exceptional benefits
In addition to our collaborative culture and employee ownership, we offer outstanding benefits to support our employees’ well-being, financial health, and wellness. Our Student Debt Employer Contribution benefit helps pay off college loans faster.
SCS Engineers is an EOE/V/D Employer
Become one of the engineers, consultants, scientists, and technicians that help private and public entities run cleaner and more efficiently. A very rewarding place to have a career!
The Fabricated Geomembrane Institute – FGI, discusses allowable leakage rates for industry. We strive for zero leakage and it is possible – this mix of regulators and practitioners including Neil Nowak of SCS Engineers discuss how to achieve it.
Click here to start the video.
The promulgation of 40 CFR 62 Subpart OOO (EG plan), effective since June 21, 2021, impacted all MSW landfills operated under NSPS subpart WWW. One of the major changes of this rule is the requirement to monitor all cover penetrations during quarterly methane surface emission monitoring (SEM). All components that are part of the landfill gas collection system and any other object that completely passes through the landfill cover are considered cover penetrations.
As landfill and landfill gas practitioners, we suggest that advanced planning can save you time and effort. As landfills face short 10-day correction periods, coupled with supply chain and labor shortages, planning can make operations and compliance more efficient. We present a few scenarios and suggestions here.
You’ll need to record any reading greater than 500 ppm above background as an exceedance location during monitoring. These require taking corrective actions such as cover maintenance or landfill gas wellfield adjustments, along with monitoring the exceedant locations again within 10-days of your initial monitoring. If 10-day monitoring still shows methane concentrations greater than 500 ppm, you’ll need additional corrective actions and to monitor the location once more within 10-days of the second exceedance.
Once the location(s) shows methane concentrations less than 500 ppm, it is mandatory to monitor these locations again one month from the very first reading showing the exceedance. If a location shows methane concentration greater than 500 ppm for three occasions in one quarter, the addition of a collection device, other improvements to the collection system, or a request for an alternative remedy and timeline is required. Therefore, implementing appropriate corrective action within the specified timeframe is critical to avoid expensive GCCS expansions or NOVs.
Gas well, well boots, leachate risers, below and above-grade pipe transition, condensate sumps, and valve vaults are some of the common exceedant penetration locations. Implementing corrective action at these penetrations within the given timeframe is a challenging ordeal for landfill operators. Corrective action can vary depending upon several factors: the methane concentration observed during initial monitoring, the location of the penetration, cover type (geomembrane capped vs. soil capped), material availability, and resources available to perform the work.
Corrective actions have varying material and effort requirements; one solution cannot fit all challenges. The most common corrective actions include applying expanding foam, soil mounding, excavation, clean dirt fill or bentonite fill, well boot repairs, installing a prefabricated well boot seal, and installing a vacuum line for emission control. We recommend before starting your monitoring operators consider the following factors:
Develop an educated estimate for the number of expected exceedant penetrations from the landfill sections that historically show cover exceedances or are in areas with problematic operating conditions. Using the readings and data collected over time makes identifying these areas much easier.
Decide the type of corrective action to implement based on your cover type in those expected exceedance locations.
Procure corrective action materials such as bentonite, geomembrane for boot fabrication matching permitted cap material, or prefabricated seals before you need them.
Check the availability of contractors for liner or well boot repairs, and their response time, before you need them.
Surface emissions vary based on the operating conditions; therefore, it is common to see a variable number of exceedances from one quarterly monitoring event to the next. At one of our sites that had no surface exceedances observed during the previous quarterly SEM event, multiple penetrations observed methane concentration greater than 500 ppm during the following quarterly event. One section of the landfill with a soil cap observed methane concentrations up to 16,000 ppm. The geomembrane capped section observed penetration concentrations of up to 8,000 ppm methane. We implemented various corrective actions to bring these exceedant locations to compliance.
In the soil-capped section, we implemented bentonite plugs, prefabricated seals, and site fabricated geomembrane seals depending upon the observed methane concentration, exceedant location, and material availability. Pre-planning and procuring material ahead of time proved to be very helpful.
For each of these corrective actions, we opened an area about 2-ft deep and 10-ft x 10-ft. For bentonite corrective action, about a 9-inch thick bentonite slurry was filled, extending about 5-ft on each side of penetration and then filled with clean dirt.
Prefabricated seals that come in standard sizes as a slip-on for penetrations and site-fabricated geomembrane seals also covered at least a 5-ft x 5-ft area around each penetration. The sleeves at each penetration were left at least 6-inch over the ground surface after filling the excavated section with clean dirt.
In the geomembrane-capped section, we choose to use well boot repairs using geomembrane. Our task was to identify the type of geomembrane used in the cap, procure the geomembrane, identify and schedule the contractor, and install well boots in each exceeding penetration location within the 10-day timeframe. After the well boot fabrication and installation, we needed to carefully reconnect the existing drainage layer.
Implementing these corrective actions can get expensive; prefabricated seals can cost up to $300 per penetration, excluding installation. Material and contractor’s availabilities are also a significant challenge. While implementing these corrective actions, additional unforeseen challenges can arise as well. Planning ahead and having the material on site is very important for landfill operators to keep the landfill under compliance.
About the Authors:
Shrawan Singh, Ph.D., PE, is a Senior Project Professional. Stephen Descher is a Senior Project Professional. You can reach both at SCS Engineers.
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