After the 2025 fires in Los Angeles, a cross-sector collaboration formed CONSORTIUM to help fire-affected families understand and address environmental risks. CONSORTIUM established a Soil Remediation Working Group to develop clear, practical recommendations for post-fire soil cleanup.
This effort responds to the scale of devastation and environmental exposure following the fires and to the limited scope of soil testing and remediation currently available. This guide is for the many groups affected by the fires, including homeowners, renters, business owners, and insurance companies.
You do not need to solve everything immediately nor tackle it all at once. This quick-start guide outlines four simple steps you can take right away to reduce and protect yourself and your family from potential health from contaminated soil.
The health risk from contaminated soil comes from direct exposure. The less contact you have with contaminated soil, the lower your risk.
What is this guide?
This guide explains the most common options for cleaning up soil contamination after urban wildfires.
The rest of the guide explains how different cleanup methods work, when they may be appropriate, what they cost, how long they typically take, and the tradeoffs of each option. It also includes a glossary of common terms and links to additional resources.
This guide focuses on contaminated soil. It does not cover cleaning the inside of your home and is not a substitute for advice from qualified professionals.
What is soil contamination and why does it matter?
Fortunately, if soil contamination is found, there are ways to make your property safer. This process is called . Depending on the situation, it may involve removing contaminated soil, treating it, or containing it to reduce .
When a home catches fire, materials like car batteries, paint, major machinery, and appliances burn with it and can create a noxious cloud of dangerous substances. As ash, smoke, and debris from the fire settle, these can spread across the property and into the soil.
Depending on the and the amount of exposure, they may increase the of respiratory disease, neurological effects, reproductive effects, or certain cancers. Your risk depends on factors like what contaminants or are present, how much you are exposed to, and how often.
Contaminants of Concern
Heavy metals: Elements such as lead, arsenic and mercury.
: Polycyclic aromatic hydrocarbons (PAHs), which are produced during the incomplete burning of organic materials.
: Per- and polyfluoroalkyl substances (PFASs), often referred to as "forever chemicals" because they do not break down easily in the environment or human body.
Why they matter: Exposure to elevated levels of these contaminants has been linked to a range of health effects, including impacts on the brain and nervous system, immune system, thyroid, and an increased risk of some cancers.
CAP.LA and USC CLEAN have tested more than 6,000 lots across Los Angeles following the 2025 fires. The most common contaminants of concern include heavy metals like lead, polycyclic aromatic hydrocarbons (PAHs), and per- and polyfluoroalkyl substances (PFAS).
Based on what we've learned so far, CONSORTIUM has focused primarily on lead, as it's the contaminant found most often. The two testing programs that have informed this guide are USC CLEAN's self-submitted samples (lead) and CAP.LA's professionally collected samples ()
Should I be worried? Steps to reduce potential exposure.
Fortunately, there are practical steps you can take to reduce immediately while you gather information and decide what to do next.
Unless you have already tested, there's a chance your soil still holds that could affect your family's health and the value of your property.
The health from contaminated soil comes from direct exposure. The less contact you have with contaminated soil, the lower your risk.
How you can be exposed
You can be exposed by breathing in contaminated dust, accidentally swallowing soil after it gets on your hands or is tracked indoors, getting it on your skin while working in your yard, or eating food grown in contaminated soil. In some cases—especially indoor environments–contaminants can also release gases that may be breathed in.
Remediation should be the goal. While you're deciding what to do next, a few simple habits can help reduce exposure:
Wash your hands regularly, especially before eating.
Take your shoes off before coming inside.
Wet-mop floors and wipe down surfaces instead of dry sweeping, which can stir dust into the air.
If your pets spend time outside, wipe their paws and fur before they come indoors.
A HEPA vacuum or HEPA air purifier can also help reduce contaminated dust inside your home.
If you're concerned that someone in your household—especially a child, someone who is pregnant, an older adult, or another person at higher risk—has been exposed over a long period of time, you may consider medical screening. Doctors can test for exposure levels through blood or urine tests. (See Resources)
Cover bare soil while you decide
If you have children or pets, or you'll be living on the property while you decide on remediation, covering bare soil with 2–4 inches of clean material can reduce exposure. Clean soil, quartz sand, gravel, compost, or other fire-safe materials can all be used to create a temporary barrier.
What Activities Increase Exposure Risk?
Activity
Relative risk
Recommended precautions
Children playing in soil
Highespecially for children under 6
Cover exposed soil with clean soil/fire-safe materials
Gardening in soil
Highfor certain crops (i.e., leafy greens or root vegetables) if no preventative measures are taken
Use raised beds with clean soil; add organic matter to soil
Walking through yard
Lowbut can track soil into the house
Keep soil covered and remove shoes on entry
Pets digging
Medium
Limit access to exposed soil and wipe paws
Rebuilding
Highif dust control measures are not used, especially for workers
Ensure that your contractor has a plan for dust control
What is soil testing and how do I know if I need it?
is the only way to know if remediation is necessary to address contamination.
During a soil test conducted by professionals, small amounts of soil are collected from several locations across your property. Each sample is placed in a labeled container and sent to an . At the lab, the soil is prepared and run through instruments that can identify and measure different . The lab then provides a report showing which contaminants were found and how much of each was present.
Taking multiple samples or samples from multiple areas on a property is important. Soil contamination can vary significantly even within the same property, so a single sample may not reveal hotspots.
Even if your neighbor has tested their soil, you should test the soil on your property because contamination can vary widely from one place to another.
How much testing is enough?
Suggested guidance:
For residential lots less than 3,500 sq ft: minimum of three per area of concern (e.g., front yard, back yard, garden).
If you want more precise targeting for remediation, visit this link to understand more robust sampling methods (or consult a professional).
Prioritize areas where and contamination are most likely
Exposed soil
Gardens
Children's play areas
Downspouts
Ash/debris areas
If rebuilding, test areas likely to be disturbed during grading.
I want to test. How do I do that and what do I ask for?
There are two main avenues to test your soil: you can hire specialists to come on-site and collect samples, or you can collect the samples yourself and submit them to a free testing program. If you are collecting samples yourself, be sure to wear disposable gloves, a dust mask, long pants, long sleeves, and closed-toed shoes. A list of local labs and programs can be found here.
Recommended testing from a professional lab includes:
heavy metals (this includes )
(Cr6)
(Polycyclic Aromatic Hydrocarbons), if available
Ask for chain-of-custody
Ask the lab to include chain-of-custody documentation with your results.
If you are unable to access professional testing, you can self-submit samples to USC's free CLEAN program, but a few things to note:
This program tests mainly for lead. It is the most commonly found , and may be a good indicator to help determine if other contaminants may be present in your soil.
To obtain a remediation plan, a professional test will be necessary.
A self-submitted test may not suffice for legal claims for damages, so if you plan to claim the cost of testing or remediation, a professional test (with chain of custody) may be required.
Learn more about how soil testing decisions can affect insurance, litigation, and future property sales.
Once I have the results, how do I know what they mean? Do I even need remediation?
When your soil test results come back, you'll be looking for .
An exceedance means a was found above the set by the U.S. Environmental Protection Agency (EPA) or California EPA. Residential screening limits are designed for places where people live and account for everyday activities like children playing in the yard, gardening, and tracking soil indoors. This guide uses residential screening limits for that reason. Soil test results are usually reported in , also called , which is the term we use in this guide.
For example, if your results show 100 ppm of (Pb) and California's residential screening limit for lead is 80 ppm, that sample exceeds the screening limit. But, whether this level poses a health depends on how you interact with that area of your property.
If your lab report doesn't identify which results are exceedances, compare your results to the residential screening limits yourself or call the lab and ask them to explain your results.
For lead, the residential screening limit is 80 ppm (California EPA) and 200 ppm (U.S. EPA). California often sets public health goals and contaminant limits that are more stringent than federal EPA standards. USC CLEAN has published a guide to interpreting lead test results, and CAP.LA has published a Soil Sample Information Sheet.
A summary table outlining residential soil screening limits is provided here.
What do screening limits mean?
Screening limits are not a strict line between "safe" and "unsafe." They are conservative public-health benchmarks used to guide decision-making and reduce long-term .
Your actual risk depends on:
How contaminated the soil is.
How often people come into contact with it.
Whether contaminated soil is covered.
Who is being exposed, as children and pregnant people are generally more vulnerable.
If your results show exceedances
Whether to remediate contaminated soil is a decision that depends on your property's contamination levels, how you use the land, your goals, your budget, and your comfort with .
If your results show , you may want to consider remediation. This is especially true for households that have children under age six, pets, pregnant individuals, or people with health concerns.
Lead concentration thresholds
For properties with greater than 80 , explore further testing if vulnerable populations are regularly on the property, including children under age six and pregnant people.
For properties with lead concentrations greater than 200 ppm, professional remediation is recommended.
But even when levels are below screening limits, some households may choose to pursue remediation based on their own preferences or desires.
Toxic substances + direct exposure = exposure risk
Risk arises when there are toxic substances present AND there is direct to them at relevant doses.
Several different professionals may be involved in , and each has a different role:
An tests your soil and reports what was found.
An /industrial hygienist interprets your test results and recommends a remediation strategy. They also explain any long-term maintenance, testing, or land use restrictions associated with that approach.
A contractor performs the remediation work.
A laboratory may provide an interpretation of your results and, in some cases, remediation recommendations. If it does not provide interpretation, consider having a or residential soil specialist review your results.
Before starting remediation, have your results reviewed by an independent . If you're considering a method that leaves contamination on your property (such as capping or immobilization), ask the person designing your remediation plan to explain any future maintenance, inspections, testing, or restrictions before work begins. Request that information in writing. After the work is complete, request a written completion report documenting the remediation performed, confirmation testing results, and any recommended long-term maintenance, testing, or land-use restrictions.
The goal of remediation is to eliminate or at least reduce your to contaminated soil. Remediation generally focuses on one of two approaches:
1
Removing the contaminated soil and replacing it with clean soil.
2
Reducing exposure so people don't come into contact with contaminated soil.
These approaches are not mutually exclusive. Many remediation projects combine both strategies to provide additional protection. Do not attempt to remove contaminated soil yourself. Digging, moving, or disturbing contaminated soil can increase your exposure and spread contamination to other areas. Most remediation methods require specialized training, equipment, and safety procedures.
Maintaining a Capping or Containment System
If your remediation plan relies on keeping contaminated soil covered, inspect the area regularly for bare soil, cracks, holes, or other places where the underlying soil may be exposed. Repair these areas promptly to maintain the protective barrier. If you are using compost or another organic cover, add about 4 inches every 12 months, or sooner if soil becomes exposed, since these materials naturally break down over time. If you are using sod, repair dead patches or bare spots as they appear. If you are using gravel, replenish it only where it has shifted or where soil has become exposed.
There are four main remediation methods recommended by CONSORTIUM for residential properties. Each option has different costs, timelines, and long-term maintenance requirements. Depending on what you have in your soil, some remediation options may be more effective than others for your particular situation.
REMOVE SOIL
Excavation & Disposal
The contaminated soil is excavated, taken to an approved disposal facility, and replaced with clean soil. Because the contamination is physically removed, this provides the highest level of certainty and usually requires the least long-term maintenance.
Best for
All common .
Cost
Can be up to $50,000 or higher per site depending on the amount of soil excavated.
Timeline
FAST: Days to weeks once contractor is secured.
Scientific confidence
High
Maintenance
None after successful completion.
Testing
Test after completion of .
REDUCE EXPOSURE
Capping
Contaminated soil is covered with a protective barrier such as clean soil, quartz, gravel, concrete, or pavement. The contaminants remain in place, but capping prevents people from coming into contact with them as long as the barrier is maintained.
Best for
All common contaminants.
Cost
~$10,000-$100,000 per site depending on materials used, grading required, etc.
Timeline
Days to weeks once the contractor is secured.
Scientific confidence
High if maintained properly
Maintenance
LOW: Cement, concrete, asphalt. MEDIUM: Landscape barrier + Mulch, soil, or gravel. Inspect annually and after major storms or disturbance. Repair erosion or damage, maintain any protective cover, and restore the treated area if it is disturbed. Ongoing cost is a consideration for Capping..
Testing
Retesting is recommended on an annual basis or if the cover is damaged or disturbed.
REDUCE EXPOSURE
Immobilization
Materials such as compost, biochar, zeolites, or phosphorus are added to contaminated soil. These amendments can to contaminants and reduce how easily they move through the environment or are absorbed by people, plants, or groundwater. Stabilization is not effective for every contaminant or extreme , and some immobilized contaminants can become mobile again if soil conditions change.
Best for
Many hazardous metals including , cadmium and . Some .
Cost
~$10,000-$50,000 per site depending on materials used and monitoring/testing required.
Timeline
Days to weeks once the contractor is secured.
Scientific confidence
Low-moderate
Maintenance
HIGH: Inspect annually and after major storms or disturbance. Repair erosion or damage, maintain any protective cover, and restore the treated area if it is disturbed.
Testing
Long-term monitoring is generally required to validate continued effectiveness.
TREAT SOIL (nature-based)
Bioremediation
Plants (phytoremediation), bacteria (microbial remediation), and/or (mycoremediation) are used to remove, break down, or reduce certain contaminants. Depending on the contaminant, plants may absorb contaminants or help keep them from spreading, while bacteria and fungi can break down some into less harmful substances. These treatments are applied directly to the contaminated soil and may be used alone or in combination with other remediation methods. The treatment area often needs to be watered and maintained while the plants or microorganisms do their work.
Best for
. Certain hazardous metals. Certain PFAS.
Cost
~$10,000-$50,000 per site depending on site and contaminant conditions.
Timeline
Weeks to years depending on the contaminants, their and the method(s) used.
Scientific confidence
High (PAHs); Moderate (metals); Low (certain PFAS)
Maintenance
HIGH: During treatment, ongoing coordination with a remediation professional is required. Bioremediation waste must be disposed of as hazardous waste and must not be thrown away or composted. No maintenance required after successful completion.
Testing
Requires periodic progress testing during treatment and final confirmation testing upon completion. Any bioremediation byproducts need to be tested and disposed of as hazardous waste.
At a glance
Excavation & Disposal
Capping
Immobilization
Bioremediation
Best for
All common contaminants
All common contaminants
Cost
Timeline
Scientific confidence
High
Low–moderate
Maintenance
Testing
For full details, see corresponding cards above
How do I choose a remediation option?
There is no single "right" solution for every property. The best approach depends on your health priorities, budget, timeline, future plans, and how much certainty you want.
As you think about your remediation options, consider:
1
Who uses the property?
Because young children, pets, and pregnant individuals face a higher of harm from , reducing direct contact with contaminated soil becomes more important.
2
Will you grow food?
Gardening increases your contact with soil, and some can be transferred to or taken up by edible plants. You will need soil that meets agricultural safety guidelines, or to use raised beds filled with clean soil.
3
What can you afford?
Full offers the greatest certainty but is often the most expensive. Targeted removal or partial excavation, capping, stabilization, or biological approaches can also reduce exposure at a lower cost.
4
What services are available?
The best option may depend on whether contractors, disposal facilities, or remediation materials are available in your area.
5
How quickly do you need results?
Excavation and capping reduce exposure immediately, while stabilization and bioremediation methods generally take months or years and require ongoing monitoring.
6
How much certainty do you want?
Excavation physically removes contaminants from your property and provides the highest level of certainty. Other approaches can also effectively reduce exposure but leave some contaminants in place.
7
How much ongoing maintenance are you comfortable with?
Some remediation methods require ongoing costs and periodic maintenance, monitoring, or follow-up testing to remain protective over time. If you prefer a solution that requires less long-term management and faster results, excavation may be a better fit.
Many homeowners combine approaches, for example, reducing exposure right away by capping contaminants while planning longer-term remediation efforts as time and funding allows.
Note
You do not have to solve everything at once. A reasonable and effective plan often includes immediate steps to reduce exposure, a cleanup approach that fits your budget and timeline, and follow-up testing and monitoring to make sure the solution continues to work. Making an informed, practical decision that fits your situation is far better than feeling pressured into a one-size-fits-all solution.
Finally, remember that contamination doesn't stop at your property line. If your neighbors don't remediate toxic soil, contaminants can spread onto your property through:
Rainwater runoff: Water flows downhill, carrying fine, contaminated particles with it.
Wind: Dry, dusty soil can blow across property lines.
Shared landscaping or drainage: Especially if you have adjoining yards, irrigation, or a natural slope.
Working with your neighbors to understand their results and remediation plans, if needed, is the ideal approach. If neighboring properties have not yet been cleaned up, ask your contractor whether it makes sense to phase your remediation, add dust-control measures, or plan follow-up testing after nearby work is complete. Community-wide clean up coordination can reduce costs and improve long-term public health protection.
Want to connect with your neighbors? Many neighborhoods establish Neighborhood Captains or community recovery groups after a disaster. Check with your local recovery organization or neighborhood association to see what's available in your area.
How much does remediation cost?
If you need to pay out of pocket, it may be worth getting multiple estimates and asking whether remediation can be completed in phases or focused on the areas with the highest contamination.
The cost of remediation depends on the size of your property, the present, and the cleanup method you choose. Insurance coverage also varies, and some policies may not cover soil contamination or testing.
Some survivors have also been able to include and remediation costs in litigation, and additional community or publicly-funded remediation programs may become available over time.
Always ensure you obtain remediation quotes from appropriately licensed and bonded contractors to perform this work.
Insurance coverage for soil testing and remediation varies by policy. While most policies do not cover soil, it is still worth asking your insurer what may be reimbursable. A list of questions you might ask can be found below. Be sure to document all activities carefully and keep records of all testing results.
Is soil contamination covered under my policy?
Are soil testing costs reimbursable?
Are temporary reduction measures covered?
What documentation do you require?
How do I find a remediation contractor?
Choosing a remediation contractor is an important decision. Look for a contractor with experience cleaning up residential post-fire contamination who is willing to review your soil test results before recommending a remediation strategy. A qualified contractor should explain the available remediation options, discuss the benefits and limitations of each, and clearly explain why they recommend a particular approach for your property.
For a checklist of questions to ask while vetting a contractor, click here.
As a best practice, consider having your property evaluated by an independent expert, such as a or Professional Geologist, before remediation begins. Once a remediation plan has been developed, the work should be performed by a licensed contractor with the appropriate safety training.
Questions to ask a remediation provider
Are you licensed in California?
Do you have HAZWOPER training?
Have you worked on residential post-fire contamination?
Could I speak with any previous clients?
Will you provide a written remediation plan?
How will you prevent contaminated dust from spreading during the work?
How will you confirm the remediation was successful?
Where will contaminated soil be taken for disposal (if is needed)?
Will you provide documentation of the completed work and any follow-up testing?
Learn about common scams and how to avoid them here.
FAQ
Should I remediate my soil myself?
It is not advisable.
Most is best left to qualified professionals. Contamination is often invisible, and digging, moving, or disturbing contaminated soil can spread and increase your .
A qualified remediation professional can:
Interpret your soil test results.
Determine where and how deeply soil needs to be treated.
Prevent contamination from spreading during the work.
Safely handle and dispose of contaminated soil or other remediation byproducts.
Confirm that the remediation was successful through follow-up testing.
There are a few things you can safely do yourself to reduce exposure while you decide on next steps, such as covering bare soil, installing raised garden beds with clean soil, and using good indoor cleaning and air filtration practices. Review our QuickStart Guide.
If you need to work around potentially contaminated soil, wear an N95 respirator, gloves, and dedicated work shoes or shoe covers, and avoid generating dust whenever possible.
For any work beyond these basic exposure-reduction measures, talk with a qualified remediation professional before getting started.
Can I have my soil remediated while rebuilding or living on the property?
In some cases, yes, but it requires careful planning.
Activities such as digging, grading, or moving soil can create dust and increase exposure if they are not properly managed. For that reason, remediation is often coordinated with construction and completed in stages, with measures in place to control dust and contain contaminated soil.
If you are living on the property during remediation, your contractor may recommend additional precautions, such as covering exposed soil, limiting access to work areas, using protective equipment when necessary, and increasing cleaning to reduce exposure.
Combining remediation with rebuilding can often be more efficient than treating the site separately, but it should be planned and carried out by qualified professionals.
What if my neighbor is remediating their property while I'm living next door?
Soil remediation can create dust if contaminated soil is being excavated or moved. A qualified remediation contractor should use measures to control dust, limit the spread of contaminated soil, and protect neighboring properties during the work.
If you're concerned, ask your neighbor or their contractor what steps they're taking to control dust and manage contaminated soil. While work is underway, keep windows closed during dusty activities, run an air purifier indoors in each room, and avoid the active work area.
If you observe excessive dust, soil leaving the site, or other unsafe practices, you can raise your concerns with the contractor or the appropriate local agency.
Do lead and other contaminants go away if I cover the soil with compost or other materials?
No. Covering contaminated soil doesn't make the contamination go away.
Instead, it creates a temporary barrier between you and the contaminated soil, reducing the chance that you'll come into contact with it. Some soil amendments can also help keep contaminants from moving through the soil or being taken up by plants.
and other metals remain in the soil unless the contaminated soil is removed. That's why methods like capping and stabilization reduce exposure, while removes the contamination from your property.
What happens when it rains? Can storms move contaminated soil?
Rain does not eliminate contaminants such as lead or other metals from soil. Instead heavy rain, flooding, erosion, or mudslides can further expose contaminated soil or move it to other areas. In some cases, contaminated soil can also be carried onto neighboring properties, particularly on sloped lots or where bare soil is exposed.
If your remediation plan relies on capping or containment, inspect your property after major storms to make sure the protective cover is still intact. Repair any areas where contaminated soil has become exposed.
If you notice significant erosion, flooding, mudslides, or other soil movement after a storm, consider talking with your remediation professional about whether additional is appropriate.
What should I do if I think I have been exposed to lead or other contaminants?
If you think you or your child may have been exposed to lead, contact your healthcare provider. Most people with lead exposure do not show symptoms, so the only way to know whether exposure has occurred is through a blood lead test.
Many healthcare providers offer blood lead testing for young children. If you have questions about lead exposure or need help finding testing services, contact the County of Los Angeles Department of Public Health for information and resources.
Should I be worried about pets spending time in the yard?
Pets can also be exposed to contaminants in soil. Because they dig, roll, and walk through the yard, they can come into direct contact with contaminated soil and track it into your home.
Until your property has been remediated or contaminated soil has been safely covered, keep bare soil covered with a thick layer of gravel or clean soil, and discourage pets from digging in exposed areas. Wiping paws before pets come inside can also help reduce the amount of soil tracked indoors.
Is it safe to eat food grown in my yard?
Whether homegrown fruits and vegetables are safe to eat depends on the contaminants present, the type of crop, and how it was grown.
If your soil is known or suspected to be contaminated, there isn't a simple yes-or-no answer. Some contaminants can be absorbed by certain plants, while others may remain on the surface of produce or in the surrounding soil. If you're concerned, consider having your produce tested and follow practices to reduce exposure while gardening.
How can I garden more safely if my soil is contaminated?
If you're gardening in an area with known or suspected soil contamination, you can reduce your exposure by following a few simple practices.
Wash your produce. Wash all fruits and vegetables before eating. Peel root vegetables and remove the outer leaves of leafy greens.
Keep soil outdoors. Wear gardening gloves, wash your hands after gardening, leave garden shoes outside, and use doormats to reduce the amount of soil tracked indoors.
Protect children from soil exposure. Keep contaminated soil covered, discourage children from eating or playing in bare soil, and wash toys and pacifiers regularly.
Keep your home clean. Mop floors regularly and replace your air and vacuum filters regularly to help remove soil that makes its way indoors.
Reduce exposure from pets. Wash or wipe down pets as needed, wash your hands after handling them, and limit their access to contaminated soil.
Keep contaminated soil covered. Maintain a complete layer of mulch or other organic material, such as straw, wood chips, or leaf mulch, over bare soil.
Choose your garden location carefully. Avoid growing edible crops directly next to buildings, busy streets, or other potential sources of lead.
Maintain a near-neutral soil pH. If needed, add compost or lime to help keep soil near a neutral pH, which can reduce how readily some metals are taken up by plants.
Use raised beds or containers. Grow edible plants in raised beds or containers filled with clean soil. Keep in mind that this does not eliminate contaminants that may settle on plants from the air.
Choose lower- crops. Fruits, nuts, and berries generally take up fewer contaminants than many other edible plants.
Gardening Resources
How to garden safely when there might be soil contamination:
Soil and Best Practices for healthy gardens, Cornell Waste Management Institute Resources for Healthy Soil. Available at: http://cwmi.css.cornell.edu/soilquality.htm
Home gardens and , what you should know. UC-agricultural-extension. Available at: https://anrcatalog.ucanr.edu/pdf/8424.pdf
Soils in Urban Agriculture: Testing, Remediation, and Best Management Practices, Department of Toxic Substances Control. Available at: https://dtsc.ca.gov/wp-content/uploads/sites/31/2020/05/Exide_FS_Soil_ADA.pdf
Best practices for urban gardens fact sheet, Compost Education Centre. Available at: https://compost.bc.ca/programsresources/factsheets/
Bios & acknowledgements
Prepared by lead author Dr. Danielle Stevenson, with contributions and review from the CONSORTIUM Soil Remediation Working Group:
Shaily Mahendra, UCLA
Christine Sierra O'Connell, Chapman University
Danielle Stevenson, Centre for Applied Ecological Remediation
Maureen Jerrett - Technical Writing
Sujeet Rao, USC, CLEAN
Erika Garcia, USC, CLEAN
Sanjay Mohanty, UCLA, CAP-LA
CONSORTIUM · Plain-language
Glossary
Accredited laboratory
A laboratory officially approved by a government or other authority to run tests and report results. These labs meet strict quality standards to ensure their results are reliable and can be used for legal, regulatory, or official purposes.
ExampleAn accredited lab test for lead in soil can be used in a court case or for insurance or regulatory reporting.
Aerial deposition
The process by which particles in the air (from smoke or ash) collect or deposit on solid surfaces such as soil or plants.
Bind
Become attached, stuck, or immobile. Using lead as an example, binding lead means it is attached to soil or organic matter particles and not likely to rapidly leach into water, be absorbed by plants, or be blown away as dust.
Bioavailability
How much of a chemical or contaminant can actually get into the body after exposure and cause harm. Not everything we touch or swallow is absorbed–some passes through without entering the body. Bioavailability depends on the chemical itself and the way exposure happens.
ExampleIf lead is in soil but locked inside tiny rock pieces, it likely has low bioavailability. If it is dissolved in water droplets or present in dust that can be swallowed, the bioavailability is higher.
CAM 17
The California Assessment Manual list of 17 hazardous metals that California recommends for soil testing. The panel includes lead and other metals of concern.
ExampleAsking a lab for "CAM 17" tells them to test your soil for all 17 of these metals at once.
Cap
To cover soil with a barrier that is not easily penetrated. This may prevent plant absorption of contaminated soil or limit dust that can lead to contamination exposure. Examples include compost, topsoil, membrane, woodchips, gravel, or sod.
Certified Industrial Hygienist (CIH)
An environmental professional certified to identify and evaluate health hazards, including contaminated soil. A CIH can review your soil test results and advise on next steps. In California, you can find one through the AIHA Consultants Directory or the BGC Directory of Certified Industrial Hygienists.
Chemical
A substance with a specific composition and set of properties. Chemicals can occur naturally (such as water or oxygen) or be manufactured (such as many cleaning products or pesticides). Some chemicals are harmless, while others can pose health or environmental risks depending on the amount and type of exposure..
Composite sample
A single mixture created by combining multiple individual smaller samples collected from different locations. It is analyzed as one unit to provide an average measurement.
Concentration
The amount of something in a fixed volume, expressed as a number with units.
ExampleThere is 300 ppm of lead in the soil sample taken beside the back door of the house.
Contaminant
A contaminant is any substance that is introduced into the soil and negatively impacts its quality, making it harmful to plants, animals, or humans in a dose-dependent manner.
Environmental professional (or consultant)
A specialist who interprets your soil test results, recommends a remediation strategy, and explains any long-term maintenance, testing, or land use restrictions that come with that approach.
Excavation
The process of digging up and removing, or disposing of soil.
Exceedance
A test result showing that a contaminant was found above the residential screening limit set by the U.S. EPA or California EPA.
ExampleIf the lead screening limit is 80 ppm and your soil shows 100 ppm, that result is an exceedance.
Exposure
The amount of contact a person has with a hazard, such as certain chemicals, dust, or bacteria. Exposure can happen by breathing it in, touching it, or swallowing it. The higher or longer the exposure, the greater the chance of harm.
ExampleBreathing in smoke from a fire exposes you to harmful chemicals.
Fungi
A group of living organisms that includes mushrooms, molds, yeasts, and many other species. Fungi are different from plants, animals, and bacteria. Many fungi are beneficial and play important roles in breaking down organic matter, supporting healthy ecosystems, and even helping clean up contaminated soil and water.
Hazard
A hazard is a source or a situation with the potential for harm in terms of human injury or ill health.
Examplelead in residential soil is a hazard.
Hexavalent chromium (chromium-6)
A toxic form of the metal chromium. Chromium can exist in different forms, and the hexavalent form is the harmful one. It is a known cancer-causing agent and can be present after urban fires.
ExampleA soil test may report chromium-6 separately from total chromium.
Lead
A metal that is widespread in the environment (especially soil and water). It is used in many products (e.g., leaded gasoline, batteries, plumbing, agrichemicals, etc.) and is an airborne contaminant present in industrial emissions. It is especially dangerous for young children and pregnant women. It can harm the brain and other organs in babies, young children, and others and lead to serious negative health impacts.
Lithium
A lightweight metal used in rechargeable batteries, including those in electronics and electric vehicles. It can be released into soil when batteries burn or break apart during a fire, so some post-fire testing panels include it.
Milligrams per kilogram (mg/kg)
A unit of measure quantifying the milligrams of substance per kilogram of weight. Mg/kg and ppm are equivalent.
Example80 mg lead (or Pb) per kilogram of soil.
Organic soil contaminant
A carbon-based contaminant, manufactured or derived from something that was once alive. These can be broken down and transformed into less or non-toxic soil by decomposer microbes.
Examplediesel, gasoline, pesticides, etc.
Parts per million (ppm)
A unit of measure used to describe very small concentrations of a contaminant in a larger substance.
Example1 ppm of lead (Pb) means 1 part lead per every 1,000,000 (1 million) parts soil (or 1/1,000,000).
Per- and polyfluoroalkyl substances (PFAS)
A large group of human-made chemicals used in products such as nonstick coatings, waterproof materials, and some firefighting foams. They are often called "forever chemicals" because they resist breaking down and can persist in soil and water for a long time.
Phyto-extraction
The process in which plants remove metals from soil or water into their above-ground parts, thereby cleaning the soil.
Phyto-stabilization
The process in which plants bind or hold onto metals in their roots, preventing them from leaching into water or moving up into the plant or blowing away as dust.
Polycyclic aromatic hydrocarbons (PAHs)
A group of carbon-based (organic) chemicals that form when wood, fuel, plastics, and other materials burn. They are common in post-fire soils. Because they are organic, some can be broken down over time by soil microbes through bioremediation.
ExampleSoot and char left after a structure fire can contain PAHs.
PPE (Personal Protective Equipment)
Clothing or gear people wear to stay safe when working around hazards. PPE protects the body from things like chemicals, dust, heat, or germs.
ExampleGloves, masks, and goggles worn during soil sampling.
Risk
The chance that something bad could happen because of a hazard. Risk depends on how dangerous the hazard is and how likely people are to come into contact with it.
ExampleThere is a risk of getting exposed to lead when sampling soil on sites that have been impacted by fire.
Residential screening limit
The level of a contaminant in soil (or water or air) that is not considered a major risk for most people in everyday use. If your test result is higher than the screening limit, it may pose a health risk and should be looked at more closely.
ExampleIf the screening limit for lead in soil is 80 ppm, and your soil has 120 ppm, it is above the screening limit.
Soil contaminant analysis
The process of determining the concentration(s) of contaminant(s) of concern in a soil sample.
Soil metal
An elemental and inorganic contaminant found on the periodic table. Some metals are toxic at any concentration (Pb) whereas some are only toxic when in certain forms, for example, mercury (Hg) and chromium (Cr). Others are only toxic above certain concentrations, such as arsenic (As) and cadmium (Cd). Some are essential nutrients or minerals, such as zinc (Zn), but are toxic above certain concentrations. Metals are non-biodegradable (meaning they don’t break down through microbial action) and persist in the environment.
Soil testing
A process of taking scoops of soil from an area and sending them for analysis to determine whether there are contaminants present and in what concentrations.
Soil remediation
The cleanup of contaminants in soil by removing, treating, or containing them to reduce exposure.
ExampleDigging up and replacing contaminated soil is one form of remediation.