Hydrologic and Hydraulic (H&H) Modeling is used in engineering analyses to evaluate water bodies, pipes, culverts, channels, and rainfall. H&H Models enable the evaluation of drainage and/or flooding impacts of various development or restoration scenarios and support the development of design and policy solutions.
Stormwater Compliance Requirements Set for Hundreds of Facilities in LA’s Dominguez and Los Cerritos Watersheds Effective October 31, 2026.
For the first time in California’s long water-quality history, a new stormwater permit has been adopted that could significantly change the California waterscape. This new permit represents a major expansion of stormwater regulation beyond the traditional California Industrial General Permit (IGP). While the application is limited to two Los Angeles watersheds, the precedent is clear and could lead to increased stormwater regulations statewide.
Commercial, Industrial, and Institutional Facilities Impacted
The new Waste Discharge Requirements and General National Pollutant Discharge Elimination System (NPDES) Permit No. CAS004005 issued by the California Regional Water Quality Control Board, Los Angeles Region regulates stormwater discharges associated with commercial, industrial, and institutional (CII) facilities within the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed and the Los Cerritos Channel/Alamitos Bay Watershed.
Several hundred industrial and institutional facilities in the Dominguez Channel and Los Cerritos Channel watersheds are subject to permit compliance requirements. These facilities must manage stormwater runoff and authorized non-stormwater discharges because their discharges can contribute to water quality.
Most parcels are owned or leased by large businesses, which are expected to bear the majority of compliance costs. The permit’s requirements are estimated to represent a small percentage of average commercial or industrial rents. The permit also considers the economic benefits of improved water quality, including public health and tourism benefits.
General Permit Coverage and Applicability
The permit authorizes discharges of stormwater runoff and authorized non-stormwater discharges (NSWDs) from certain privately owned CII sites, excluding residential facilities.
Coverage includes sites with five or more acres of impervious surface that are not covered by other NPDES stormwater permits, or portions of sites not covered by other permits. Facilities with individual NPDES permits with at least as stringent requirements are exempt.
Dischargers must submit Permit Registration Documents via the Stormwater Multiple Application and Report Tracking System (SMARTS), including:
Notice of Intent (NOI),
Site-specific Stormwater Pollution Prevention Plan (SWPPP),
Initial sampling results, and
Compliance option documents
Compliance Options
Permittees and dischargers will have three primary compliance options for meeting water quality-based effluent limitations:
Option 1: Enter into a legally binding agreement with a local Watershed Management Group (WMG) to fund existing or planned downstream regional stormwater projects. Funding is proportional to the facility’s stormwater volume relative to the watershed’s total volume. This option is deemed compliant upon execution of the agreement and participation in it.
Option 2: Implement facility-specific design standards to capture and reduce stormwater runoff volume equivalent to the 85th percentile 24-hour storm event. This includes the use of structural and non-structural BMPs designed and certified by a California-licensed civil engineer. Infiltration BMPs must protect groundwater quality by meeting applicable Maximum Contaminant Levels (MCLs).
Option 3: Directly demonstrate compliance with numeric water quality-based effluent limitations through site-specific monitoring and reporting. This includes developing a Monitoring and Reporting Plan, conducting sampling during Qualifying Storm Events (QSEs), and submitting results via SMARTS.
Discharge Prohibitions and Authorized Non-Stormwater Discharges
The permit prohibits discharges inconsistent with eligibility, unauthorized non-stormwater discharges, trash discharges, and discharges of radiological, chemical, or biological warfare agents. Authorized NSWDs include fire hydrant flushing, potable water system discharges, uncontaminated groundwater, and incidental windblown mist, provided BMPs minimize pollutant contact and volume.
Stormwater Pollution Prevention Plan (SWPPP) Requirements
Dischargers must develop and implement a site-specific SWPPP including:
Facility contact information and operational hours.
Establishment of a Stormwater Pollution Prevention Team with defined roles.
Site map detailing boundaries, drainage areas, stormwater conveyance, BMP locations, impervious surfaces, and pollutant sources.
Description and assessment of potential pollution sources.
Implementation of minimum BMPs such as good housekeeping, exposure minimization, and employee training.
Documentation of structural and non-structural BMPs in summary tables.
Effluent Limitations
The permit establishes both technology-based effluent limitations (TBELs) requiring implementation of BMPs reflecting Best Conventional Technology (BCT) and Best Available Technology economically achievable (BAT), and water quality-based effluent limitations (WQBELs) based on Total Maximum Daily Loads (TMDLs) and water quality objectives. Numeric effluent limits apply to specific pollutants including metals (copper, lead, zinc), indicator bacteria (Enterococcus, E. coli), toxicity, nutrients, legacy pesticides (DDT, chlordane, dieldrin), and PCBs in various receiving waters.
Sediment-associated effluent limitations are also established for certain pollutants in the Dominguez Channel Estuary and Los Angeles and Long Beach Inner Harbor Waters.
Monitoring and Reporting Requirements
All dischargers must conduct initial sampling within 18 months of the permit effective date to assess pollutant levels. Reporting includes annual visual observations of discharges, BMP implementation, and corrective actions. Specific monitoring requirements vary by compliance option:
Option 1: Annual reporting of funding agreements and visual observations during two Qualifying Storm Events (QSEs) per reporting period.
Option 2: Submission of design documentation, reporting of any bypass events, and annual inspection reports of BMPs.
Option 3: Detailed site-specific monitoring plans with sampling during four QSEs annually, analysis for all applicable pollutants, and submission of results and visual observations via SMARTS.
Provisions and Enforcement
Standard provisions consistent with federal regulations are included, such as a duty to comply, inspection rights, a prohibition on bypasses except under specific conditions, and requirements for proper operation and maintenance. Enforcement actions and penalties for violations are described, including mandatory minimum penalties for serious violations. Corrective actions must be taken for any exceedances of effluent limitations.
Special Provisions
The permit includes reopener provisions allowing modification or revocation for cause, including new information or changes in regulations. Electronic signature and certification requirements ensure compliance with electronic reporting rules. The permit continues in effect beyond its expiration date until a new order is adopted.
Watershed and Receiving Water Descriptions
The permit covers discharges to waters within the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed and the Los Cerritos Channel/Alamitos Bay Watershed, including Machado Lake sub-watershed. These watersheds are highly urbanized and include estuaries, harbors, lagoons, and coastal waters that support diverse aquatic life and endangered species. Many waterbodies are listed as impaired under the Clean Water Act and subject to TMDLs for various pollutants.
Prepare for the CII Permit
Screen your facility, using the >5-acre threshold and other NPDES parameters from the State Water Resources Control Board (SWRCB). Further consultation is likely needed as the CII Permit leaves the traditional SIC Code and Sector-based selection to geography and land use.
Start baseline copper/zinc source investigations before regulatory sampling drives stormwater management decisions. This has the potential to save considerable money later. The EPA expressly identifies copper and zinc impairment as a basis for the residual designation.
Sources that could cause or contribute stormwater pollutants of concern to this impairment include outdoor materials and activities, including galvanized roofing and fencing; metal roofs/downspouts; brake/tire wear; parking areas; HVAC equipment; dumpsters; outdoor metal storage; loading areas; vehicle traffic; wash areas; industrial fallout; and legacy site conditions.
SCS recommends seeking a Property and Applicability Screening as a first step. Some facilities may require Facility Compliance or Pollutant Source Assessments, and a Compliance Option Analysis to determine a roadmap to compliance.
Reducing risk and preserving value, culture, and habitat are the aims of Environmental Due Diligence experts.
When a land trust, public agency, or community partner works to preserve open space, the public often sees the result: protected habitat, new recreational access, or cultural resources safeguarded for future generations. Less visible—but just as important—is the environmental due diligence that happens behind the scenes.
Environmental site assessments, All Appropriate Inquiries, and remediation planning help buyers and public-sector partners understand a property’s history, identify potential environmental liabilities, and determine whether land can be safely transferred, conserved, restored, or opened for public use.
Conservation Begins with Knowing the Land
Recent projects in Arizona show how environmental due diligence supports land preservation. SCS Engineers has conducted five Phase I Environmental Site Assessments for Trust for Public Land in recent years, helping evaluate environmental concerns before real estate transactions move forward. These assessments found no need for additional assessment, supporting preservation efforts that include culturally and ecologically significant land along the Lower Gila River and acreage connected to Saguaro National Park.
That early review matters because public land acquisitions often involve properties with long and complex histories. Former agricultural, ranching, industrial, mining, or developed sites may carry environmental questions that must be answered before a nonprofit, municipality, federal agency, or other public entity assumes ownership or stewardship responsibilities.
Environmental Due Diligence Reduces Risk and Supports Public Trust
Environmental due diligence is more than a transaction requirement. It is a practical risk-management tool that helps protect public dollars, project schedules, and long-term stewardship goals. Through Phase I Environmental Site Assessments and All Appropriate Inquiries, environmental professionals review historical records, inspect properties and adjoining land, evaluate regulatory records, and identify recognized environmental conditions that could affect acquisition, funding, liability, or future use.
For land trusts and public agencies, this process helps answer critical questions: Is the property suitable for transfer? Could contamination create unexpected cleanup costs? Are additional investigations needed? Can the buyer qualify for landowner liability protections? The answers help decision-makers proceed with confidence and avoid turning a conservation win into an unmanaged environmental obligation.
Environmental Due Diligence Resources:
TheTrust for Public Landpurchased the land from the Rezzonico Ranches to preserve its archeological treasures, including four pre-Hohokam and Hohokam village sites dating from approximately 700 to 1250 CE. Each village includes a ball court, one of the most distinctive and significant features of Hohokam culture.
SCS has also assisted the Trust for Public Land in assessing 20 acres as part of a land-protection project at Saguaro National Park.
How Will Radon Testing Impact My Development Project? Nationwide, enhanced standards, which took effect for loan applications after June 30, 2023, aim to improve air quality, with some 2025 updates beginning to refine these requirements. Recently, significant tightening of …
Brownfields and Voluntary Remediation Brownfields and voluntary remediation projects protect human health and the environment while restoring properties to beneficial use. SCS Engineers is a pioneer in supporting public-private partnerships for this type of redevelopment …
UCLA Anderson’s Forecast in FIVE interviews SCS Engineers President Curtis Jang, who discusses his transition from CFO to President. Curtis outlines strategies for corporate leadership, capital allocation, and growth within the environmental consulting sector. His interview with Seth Katz highlights collaborative management, the alignment of corporate services for client satisfaction, and SCS’s national growth.
Working at SCS Engineers is unique because it is a 100% employee-owned environmental consulting and contracting firm. This structure ties company success to employee financial gain, so instead of profits going to outside investors, they go back to the workforce to build retirement wealth.
Mission-Driven, Environmentally Focused Work Core Purpose
Every day, we protect the air, soil, and water for public and private clients who provide essential services and products. We turn contaminated properties into vibrant communities, capture carbon, convert landfill greenhouse gases into clean energy, convert waste into reusable products, and ensure supermarket food stays fresh, among other things.
Dynamic Work Environments
Many technical positions combine office tasks with independent field operations, using advanced instrumentation and green technologies, creating well-rounded environmental professionals. Career development and Young Professional programs are designed to develop technically savvy, business-minded leaders early in their careers through networking and education.
In addition to strong benefits, we offer financial rewards and full support for obtaining new professional licenses, maintaining certifications, and joining professional organizations. Financial assistance is provided to employees who are continuing their higher education or pursuing advanced degrees while working alongside SCS experts.
What Employees Are Saying
According to community reviews from platforms like Glassdoor and Indeed, employees regularly praise SCS’s culture and collaborative atmosphere:
“Great people and everyone is an employee-owner… The people are the best part of SCS. Humble and hard-working. Everyone is very approachable here.” Indeed
“Employees appreciate the supportive and friendly atmosphere, emphasizing the company’s employee-owned structure that fosters collaboration and personal investment.” Glassdoor
Now on-demand! SCS focuses on surface fire risk management plans and training to prepare facilities to minimize the impact of fires and respond safely and efficiently when they occur. Besides the obvious safety and infrastructure benefits, your site may even qualify for insurance discounts.
Recorded Live on Thursday, July 16, 2026, 2:00 pm Eastern Time for 1 hour
Prevent cascading challenges by identifying and mitigating specific risks.
Unique safety risks such as toxic smoke, fire eruptions from landfill infrastructure, and the risks posed by heavy equipment operating near emergency personnel.
Fostering dialogue between a landfill or facility staff and emergency services to identify resource and knowledge gaps and ensure interoperability of communication systems.
Clarify roles and responsibilities by establishing a unified command during incidents and detailed site maps, emergency contacts, and vendor information to streamline response efforts.
Availability and importance of supplemental training sessions.
Availability of insurance impacts.
Who Should Attend? The topic is of interest to a broad cross-section of stakeholders. Because solid waste and landfill fires can escalate rapidly and carry environmental risks, anyone involved in daily facility operations, regional environmental oversight, or local emergency response should attend. SCS also gets questions from state and local agencies, who may also be interested in attending.
Meet our Experts: Our panelists include Ken Miller, who serves as the Solid Waste Agency Administrator for the City of Dubuque. Ken supports the activities of the Dubuque Metropolitan Area Solid Waste Agency’s Board of Directors, leads long-range planning and public engagement, develops new initiatives, manages projects, and ensures environmental compliance. He also serves on professional boards at both the state and multinational levels.
Jeff Phillips is an SCS senior project manager with over 24 years of experience in sustainable materials management and facility fire plans. Jeff has developed 10 fire plans for facilities across the US and has conducted more than 15 related training events involving facility staff and emergency response personnel.
EPA Proposes PFOA and PFOS Compliance Extensions and Rescission of Drinking Water Standards for Four PFAS Constituents
Proposed PFOA and PFOS Compliance Extensions
The first proposed rule, if finalized, would continue supporting the health-protective federal drinking water standards for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) while establishing an opt-in process through which eligible drinking water systems may apply for up to two additional years—until 2031—to become compliant with Maximum Contaminant Levels (MCLs).
Under the proposed rule, drinking water systems seeking the federal exemption that have one PFOA or PFOS sample result at or above 12 ppt must select and implement control measures during the exemption period and provide public education and outreach to consumers. Drinking water systems wishing to receive additional compliance time will need to seek an extension via EPA if meeting these criteria as follows:
Subject to the requirements of the 2024 PFAS NPDWR for PFOA and PFOS;
In operation on or before June 25, 2024;
Certified statement that the system cannot comply with the PFOA and PFOS MCLs by April 26, 2029, and meets other eligibility requirements for the SDWA Section 1416(a)(1) and (4) exemption:
Not currently under a Safe Drinking Water Act (SDWA) section 1415(e) variance for small systems for the PFOA and PFOS MCLs that cannot afford to comply with the MCL if EPA has identified a variance technology; and
Located in a state, territory, or Tribe that does not have primacy for the 2024 PFAS NPDWR.
Most recent PFOA and PFOS drinking water sample results and system information;
Systems that do not opt for an extension remain subject to the original 2029 compliance deadline.
The proposed compliance extension rule was published in the Federal Register on May 20, 2026. The EPA will accept written comments on the proposed rule in the public docket for 60 days at www.regulations.gov under Docket ID: EPA-HQ-OW-2025-1742.
Proposed PFAS Recission Rule
The second proposed rule is entitled Rescission of Regulatory Requirements and Removal of Related Provisions for Four PFAS Substances (PFHxS, PFNA, HFPO-DA (GenX), and the mixture of These Three PFAS Plus PFBS). If finalized, the proposed rule would address some stakeholders’ legal concerns regarding statutory requirements under the Safe Drinking Water Act (SDWA) when establishing drinking water regulations for these four PFAS constituents.
EPA seeks to clarify the sequential order for regulating a particular drinking water contaminant and to seek public comment on whether such regulation is appropriate first. Only after the public has had the opportunity to comment on that proposal and after the EPA has finalized a determination to regulate, may the EPA publish a proposed regulation for the contaminants listed in the previous paragraph.
Following the proposed recission rule publishing in the Federal Register, the EPA will accept written comments on the proposed rule in the public docket for 60 days at www.regulations.gov under Docket ID: EPA-HQ-OW-2025-0654.
Federal Register Publication and Resources
The two proposed rules will be published in the Federal Register with a 60-day public comment period, and EPA will hold a public hearing on July 7, 2026.
For more information about the proposed rules, including pre-publication versions of the proposals, fact sheets, directions for submitting comments, and information about a forthcoming public hearing, visit EPA’s webpages here and here, or contact an SCS Engineers expert near you.
Environmental compliance in printing operations involves complex interactions between materials, production processes, and regulatory permits. Small operational changes, such as material substitutions, can significantly affect emissions calculations and compliance status, even if they seem minor.
Material changes affect compliance: Switching to materials with different VOC or hazardous air pollutant contents can increase a facility’s potential-to-emit (PTE), requiring updates to emissions calculations and permit conditions. These impacts often go unnoticed on the production floor but can create compliance risks later during inspections or reporting.
Emissions driven by mass balance: Printing air programs calculate emissions based on material usage multiplied by VOC/HAP content, adjusted for capture and control efficiencies. This approach offers operational flexibility but also introduces complexity, as small formulation changes directly affect emissions.
Material substitutions are common and risky: Frequent substitutions under supply chain pressure can alter VOC content, HAP speciation, vapor pressure, and control device assumptions, impacting emissions and permit compliance if not evaluated in advance.
Potential-to-Emit (PTE) is critical: Regulators focus on PTE, which considers maximum emissions under full operation. Changes in VOC content or production capacity can increase PTE, potentially breaching permit thresholds, especially for facilities operating under synthetic minor limits.
Operational drift from permit assumptions: Over time, facilities may shift materials, usage rates, or production levels without updating permits, leading to unintentional non-compliance despite ongoing emissions tracking.
Recordkeeping is foundational: Maintaining accurate VOC/HAP usage records, emissions calculations, control device data, and hazardous waste documentation is essential to demonstrate compliance during inspections and avoid issues arising from misaligned documentation.
Best practices for compliance management: Effective facilities integrate environmental reviews into change management, align operational and emissions data, keep permit limits visible to operations, establish material approval processes, involve environmental expertise early, and periodically recalibrate permit assumptions to prevent compliance gaps.
Salt Lake City’s rapid growth is expanding into areas affected by historic mining, where mine tailings—residual materials from ore processing—pose environmental and financial challenges. However, these tailings do not inherently preclude development; rather, they should be treated as specialized brownfields that can be safely redeveloped through informed due diligence and risk-based planning.
Understanding Mine Tailings in Salt Lake City’s Growth
Utah’s long mining history has left tailings spread across large areas, which were historically viewed as inert fill but now lie beneath or near expanding development corridors. These tailings are a common due diligence concern in real estate transactions, yet misconceptions about their impact can lead developers to overestimate remediation needs. Many tailings-affected sites can be redeveloped successfully using established environmental and engineering methods.
Mine Tailings as a Unique Brownfields Remediation Condition
Mine tailings qualify as brownfields—previously disturbed lands with environmental concerns—but differ from typical urban brownfields. Unlike discrete contamination sources, tailings are shallow, widespread, and usually contain elevated levels of metals such as arsenic, lead, cadmium, or mercury, spread uniformly across large areas. This lateral, shallow nature supports practical, risk-based solutions that focus on exposure management rather than full removal, protecting human health while controlling costs.
Regional Redevelopment Examples
Across the Salt Lake Valley, various redevelopment projects illustrate that mining legacies do not preclude development. Large master-planned communities, urban infill projects, former rail and industrial corridors, and river-adjacent developments have all successfully addressed historic environmental constraints by combining thorough planning, engineered controls, soil characterization, and exposure pathway evaluation. These examples demonstrate that early investigation and regulatory coordination enable routine and feasible brownfields redevelopment, including sites with mine tailings.
Due Diligence and Site Assessment
Effective redevelopment begins with comprehensive due diligence. Phase I Environmental Site Assessments identify historical mining or smelting activities through historical maps and records. If environmental concerns are found, Phase II investigations focus on soil metals characterization, the extent of impacted materials, and exposure pathways relevant to the proposed land use. These assessments inform feasibility assessments, cost estimation, site design, and purchase negotiations, reducing uncertainty and avoiding surprises later.
Utah’s Risk-Based Regulatory Framework
Utah employs a risk-based regulatory approach allowing tailored cleanup strategies based on site conditions and intended land use. Residential projects face stricter exposure standards than commercial or industrial uses. Common regulatory measures include engineered barriers (e.g., clean soil caps, pavement), construction soil management plans, and institutional controls that document site conditions and obligations. Voluntary cleanup programs offer regulatory certainty and liability protection, integrating environmental measures into project design rather than treating them as separate remedies.
Integrating Environmental Planning into Brownfields Remediation
Successful projects integrate environmental planning with civil engineering, grading, and construction sequencing. Tailings can be managed beneath building footprints, roads, or landscaped areas, acting as engineered caps. Excavated materials can sometimes be reused on-site under controlled conditions to reduce costs and traffic. Construction-phase soil management plans help contractors efficiently handle impacted soils, minimizing delays. This approach makes environmental considerations a manageable design parameter.
Managing Risk and Financial Considerations
Uncertainty is a major risk in brownfields redevelopment. Early characterization of tailings reduces uncertainty, enabling accurate cost modeling and contingency allocation. Additional risk-management tools include environmental insurance, negotiated purchase terms that reflect known conditions, and phased development strategies that spread cleanup costs over time. Sellers often price brownfields below market value due to perceived complexity, thereby giving knowledgeable developers a competitive advantage.
Importance for Salt Lake City’s Future Growth
Mine tailings are a distinctive redevelopment challenge in the Western U.S., with Salt Lake City central to this issue. As growth continues, the number of mining-impacted sites could increase. The key is not whether development can occur, but how thoughtfully and efficiently these sites are approached. Viewing mine tailings as brownfield opportunities rather than obstacles helps us unlock strategically located land while protecting health and the environment.
Conclusion: Key Takeaway
Mine tailings should not lead to project abandonment; instead, they should prompt early, informed inquiry, engagement of experienced professionals, and integration of environmental planning into development. Through due diligence and risk-based cleanup, tailings-impacted sites can support safe, vibrant, and profitable redevelopment that meets Salt Lake City’s growth goals and those of other states with similar conditions, such as Texas, New Mexico, and Nevada.
About the Author: Thomas (Tom) Gordon, EP, serves as a senior project manager with SCS Engineers in Salt Lake City and can be reached at SCS Engineers. He specializes in environmental due diligence, brownfields redevelopment, and risk-based cleanup strategies that support development projects across the region.
Additional Brownfields Remediation Resources:
How Will Radon Testing Impact My Development Project? Nationwide, enhanced standards, which took effect for loan applications after June 30, 2023, aim to improve air quality, with some 2025 updates beginning to refine these requirements. Recently, significant tightening of …
Brownfields and Voluntary Remediation Brownfields and voluntary remediation projects protect human health and the environment while restoring properties to beneficial use. SCS Engineers is a pioneer in supporting public-private partnerships for this type of redevelopment …
A recent examination by SCS Engineers Project Directors Evan Guignon, PE, and Michael Bradford, PE, into geosynthetic liner damage and repairs examined the permeability of geosynthetic liners used in waste containment systems. Their blog focuses on the significance of lined containment, the perception versus reality of liner permeability, liner installations, and liner repairs.
Importance of Lined Containment
Lined containment is crucial for managing solids, liquids, and gases in waste containment systems. Over the past 50 years, regulations such as CCR Title 27, Title 40 CFR, and RCRA (Subtitle D) have emphasized the need for effective containment.
Liner Permeability: Perception vs. Reality
The common perception is that geomembrane barriers are impermeable and that lined ponds are watertight. However, even a “perfect” liner will leak through diffusion. The leakage rate is influenced by the head over the liner, ranging from 1 to 8 gallons per acre per day for a standing head of 1 to 10 feet deep.
Minimizing Leaks: Liner Installations
Successful liner installations involve multiple stakeholders, including manufacturers, installers, design engineers, Construction Quality Assurance (CQA) engineers, and laboratories. Common defects and damages during installation include manufacturing defects (e.g., needle holes), installation errors, equipment damage, and issues with waste/material placement. CQA (Construction Quality Assurance) engineers play a vital role in minimizing these defects and ensuring the liner’s integrity.
Detecting and Managing Leaks
Single-lined facilities use groundwater or soil gas vapor monitoring wells to detect leaks. Dual-contained facilities use leak detection systems called pan lysimeters. The EPA Action Leakage Rate (ALR) recommends 1,000 gallons per acre per day for ponds and 100 gallons per acre per day for landfills. States can set their own ALR values based on the type and function of containment. If leaks exceed the ALR, inspections and repairs are performed to address liner containment.
Liner Repairs
When damage occurs to ponds or cells, repairs are necessary. Damage can be internal (e.g., wrinkles, creases) or external (e.g., rocks, operations, environmental factors). Long-term UV exposure, catastrophic events (e.g., fire or wildlife), and slope stability failures can also cause damage. Repair solutions for ponds and impoundments involve draining, cleaning, and replacing or repairing the liner. The process for cells includes exposing them, cleaning them, and repairing or replacing the liner.
Geosynthetic Liner Conclusion
The design, material manufacturing, installation, CQA services, lab testing, and leak/damage monitoring all contribute to the overall effectiveness of the containment system. CQA, with continuous monitoring and timely repairs, is essential to maintaining the integrity of these systems.
About the Authors:
Evan Guignon, PE has experience with semiannual reporting, exceedance tracking, and regulatory compliance related to environmental projects. He has training in AutoCAD Civil 3D Advanced Landfill Grading Applications and Plant 3D Modeling. Evan’s background includes stream restoration design planning and research involving cement sample preparation and testing according to ASTM standards. Mr. Guignon holds multiple state Professional Engineer licenses.
Michael Bradford, PE brings over 20 years of experience in civil engineering and project management, specializing in solid waste landfill and public works projects. His expertise includes landfill site planning, excavation and grading design, stormwater management, geosynthetic liner design, landfill gas collection and control systems, and leachate recovery system design. Mr. Bradford has managed large-scale landfill expansions and closure projects, including permitting and construction quality assurance, and holds multiple state Professional Engineer licenses as well as CQA/CQC certification for geosynthetic materials inspection. His work includes managing permit modifications and landfill expansions that extended facility life by decades, demonstrating his capability in regulatory compliance and technical leadership.
Evolving Geosynthetic Clay Liners and Coal Ash, Waste360, Eric Nelson of SCS and EREF Researcher Kuo Tian discuss polymer-modified Geosynthetic clay liners that can manage aggressive leachate and meet EPA’s requirements. The polymer-modified alternative system is a sustainable …
Nationwide, enhanced standards, which took effect for loan applications after June 30, 2023, aim to improve air quality, with some 2025 updates beginning to refine these requirements. Recently, significant tightening of radon testing requirements for multifamily housing (five or more units), backed by Fannie Mae and Freddie Mac, includes increasing testing of ground-floor units from 10% to 25%, mandating oversight by an Environmental Professional (EP), and implementing strict tenant notification protocols.
This SCS Engineers blog by Project Professional Tyler Overton outlines recent expansions and tightening of radon testing requirements for multifamily housing in California, emphasizing updated protocols, legal compliance, and public health implications.
Expanded Radon Testing Protocols
The U.S. Environmental Protection Agency (EPA) has broadened radon testing mandates for multifamily housing, now requiring testing in 100 percent of ground-contact residential units and at least 10 percent of upper-floor units in multistory buildings for new construction and rehabilitation projects funded by HUD or other federal sources. This marks a significant shift from previous practices that sampled only 10 percent of ground-floor units. These protocols are based on updated methodologies from the American Association of Radon Scientists and Technologists (AARST) and ANSI/AARST standards, which California-certified radon professionals must follow. In addition to HUD projects, lender policies, investor standards, and local regulations, these requirements may also be enforced, making radon testing standard for both affordable and market-rate multifamily developments.
Importance of Radon Testing
Radon is a naturally occurring radioactive gas that infiltrates buildings through foundation cracks and other openings, accumulating especially in ground-contact units. It is colorless and odorless, requiring testing for detection. The EPA identifies radon as the second leading cause of lung cancer in the U.S. and the primary cause among non-smokers. Long-term exposure heightens cancer risk, underscoring the importance of radon management in residential properties, particularly multifamily housing, where many occupants may be affected.
California’s Certification and Compliance Requirements
California law mandates that radon testing and mitigation services be performed only by individuals certified through the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB), with their certifications registered with the California Department of Public Health (CDPH). Unauthorized radon services are prohibited, and violations are misdemeanors subject to fines. Compliance is thus a regulated activity with legal consequences for property owners and developers.
Radon Mitigation Procedures
If radon levels exceed action thresholds, mitigation is required. The primary method in multifamily buildings is active soil depressurization, which vents radon gas safely above the roof using piping and fans. Other measures include sealing foundation penetrations and improving sub-slab ventilation. Mitigation must comply with ANSI/AARST standards and may also relate to California Residential Code Appendix F, which addresses radon-resistant construction in new buildings. Post-mitigation testing and often long-term system monitoring are necessary to ensure effectiveness.
Geographic Considerations and Testing Necessity
Although California is not generally classified as a high-radon state, certain counties, especially in Northern California, the Sierra Nevada foothills, and parts of the Central Coast, have moderate to elevated radon potential. Both the EPA and the California Geological Survey stress that elevated radon levels can occur anywhere, making testing the only reliable way to assess radon levels. Consequently, geographic exemptions are discouraged, and standardized testing is becoming the norm for multifamily housing regardless of location.
Public Awareness and Health Promotion
Public health agencies promote radon awareness and testing as crucial for reducing risks. The CDPH offers guidance, mapping, and referrals to certified professionals, while the EPA runs national campaigns encouraging testing in all homes. California’s CDPH supports a public library program lending free short-term digital radon monitors. Despite these initiatives, radon risk remains underestimated in the state, underscoring the need for greater homeowner awareness and proactive radon management in multifamily housing.
Future Outlook
California’s evolving radon framework reflects a growing focus on environmental health in housing. With stricter testing protocols and mandatory involvement of certified professionals, radon safety is becoming a baseline expectation. For HUD or federally funded multifamily projects, understanding radon origins, risks, and mitigation is essential. As standards tighten, proactive compliance is critical to safeguard residents and preserve long-term asset value.
What’s happening in your state or commonwealth? Ask an expert!
About the Author: Meet Tyler Overton, an SCS project professional who supports clients by managing environmental projects at engineering, development, solid waste firms, and nonprofits. At SCS Engineers, his focus is on due diligence and environmental site assessments. His responsibilities include conducting Phase I environmental site assessments, regulatory compliance projects, groundwater and stormwater sampling programs, and Phase II subsurface investigations, including soil, soil vapor, and groundwater sampling.
SCS Engineers’ National Expert Eric Williams describes in his article how local governments face challenges in attracting investment to urban infill sites due to environmental risks, financial feasibility, and lengthy development timelines. By adopting a developer’s perspective, they can better position these sites for redevelopment and private investment. Read Eric’s article “Think Like a Developer: How Local Government Can Attract Urban Infill Investment.”
In a hurry? Here’s our 30-second summary of the highlights.
Reduce environmental risk: Developers require clear, quantified environmental data to manage risks. Local governments can add value by conducting environmental assessments, mitigating hazards such as asbestos, demolishing obsolete structures, and cleaning up contamination, thereby lowering upfront risks and increasing developer confidence. Even partial mitigation, when paired with clearly defined residual risks, can facilitate project planning.
Enhance financial viability: Urban infill often incurs higher costs than greenfield sites. Local governments have access to financial tools unavailable to private developers, such as EPA and state brownfield grants, Tax Increment Financing, Community Development Block Grants, economic development zones, and utility districts. These resources can close financial gaps, improve project feasibility, and serve as catalysts for investment.
Accelerate project timelines: Time-sensitive market conditions require swift action. Governments can shorten pre-development phases by proactively addressing blight and environmental issues, rezoning to support redevelopment, upgrading infrastructure, utilizing environmental review exemptions, and streamlining permitting and entitlement processes. This reduces delays that might otherwise drive developers to alternate sites.
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We use cookies to ensure the basic functionalities of the website and to enhance your online experience.
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Functional
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The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network.
Statistics
The technical storage or access that is used for statistical and/or tracking purposes.The technical storage or access that is used exclusively for anonymous statistical purposes. Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you.
Marketing
The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes.
