On this page (7 sections)
A credible bioremediation proposal answers twelve questions in writing. They start with what is in your ground and what the target is, move through how the treatment was tested and how anyone will know biology did the work, and end with who samples, which permits apply and what happens if progress stalls. The questions below draw on EPA treatability and site-characterization guidance and on published field studies. Ask them of any vendor, us included.
Your site
1. What is the baseline, and how well is the contamination mapped?
EPA’s green remediation guidance says in-place and above-ground treatment both depend on thorough delineation of source areas and a conceptual site model that is updated over time [1].
A good answer names the contaminants compound by compound, gives sample locations and depths, and states the lab method. A weak answer calls it “petroleum contamination” and gives no numbers.
2. What is the cleanup target, and who set it?
EPA’s brownfields guidance lays out a risk-based process: site characterization, then risk assessment, then a remedy chosen to meet specific cleanup and redevelopment objectives. Risk-based cleanups aim at reducing risk for the property’s intended reuse, and where contamination stays, engineering or institutional controls manage exposure [2].
A good answer points to a regulator-accepted target tied to the land’s future use. A weak answer promises to clean the site without saying to what number.
3. Can biology address this contaminant?
EPA’s technical paper says bioremediation has worked at many sites for volatile and semivolatile organic compounds, and gives PAHs, pesticides, herbicides and PCBs a more limited performance record [3]. FRTR states bioremediation is not applicable to inorganic contaminants such as metals [4]. Our contaminant fit chart sorts the common families.
A good answer says “no” outright for the parts of the problem biology can’t touch. A weak answer treats every contaminant alike.
The plan
4. Has a treatability study been done on my soil?
EPA’s treatability guidance for biodegradation describes three tiers: remedy screening, remedy selection testing, and testing to support remedial design [5]. Bench-scale tests measure the contaminant and its breakdown products on site, identify the microbes present, and show which mechanisms, amendments and doses suit the soil [1].
A good answer gives the test design, duration and result. A weak answer cites results from someone else’s site.
5. Biostimulation, bioaugmentation, or both, and what is the comparison arm?
A diesel field study ran four arms: natural attenuation, a biosurfactant, bioaugmentation, and bioaugmentation plus biosurfactant. With that design the authors could say bioaugmentation did best and the biosurfactant made no notable difference [6]. Add food and microbes together with no comparison and you can’t tell which one worked. More in biostimulation vs. bioaugmentation.
A good answer names the control, while a weak answer doesn’t have one.
6. Which organisms, and what evidence shows they act on this compound?
A full-scale groundwater project removed 98 to 99.9% of carbon tetrachloride over four years with one named strain, Pseudomonas stutzeri KC [7]. That result belongs to that strain, and a different strain with a similar name hasn’t been shown to do the same.
A good answer separates strain-level from species-level evidence and says which it has. A weak answer lists species names as though names were results. For most organisms in our own products, the published evidence is species-level, and we say so.
The proof
7. What are the by-products, and how will they be tracked?
FRTR notes that some compounds break down into more toxic by-products [4]. A chlorpyrifos study detected degradation products including chlorpyrifos oxon, so a result for the parent compound alone isn’t enough [8]. In one soil study, researchers also tested the mutagenicity of soil extracts and found it fell along with the contaminant [9].
A good answer names the expected by-products and puts them on the sampling list.
8. How will you show biology did the work, and not evaporation or dilution?
Mixing soil can make contaminants evaporate before microbes degrade them [10]. EPA’s technical paper says that measuring the rate and amount of contaminant removed, oxygen supply and carbon dioxide generation, with mass balances relating them, helps establish bioremediation as the main removal mechanism at fuel sites [3].
A good answer describes a mass balance, a control or other lines of evidence. A weak answer shows a falling concentration and stops.
9. How long, when is the first data, and what if progress stalls?
EPA says bioremediation may take a few months or several years [10]. In a published solvent comparison, one treated plot sat for three months before degradation began [11]. See how long soil bioremediation takes.
A good answer gives phases, sampling dates and a named fallback. A weak answer gives one date.
Practicalities
10. Who samples, which lab runs the analysis, and are the methods the same before and after?
EPA’s public guide says soil and groundwater are tested regularly to confirm the treatment is working and measure progress [10]. In our view, whoever samples and whichever lab analyzes should be independent of whoever sells the treatment, and the analytical method shouldn’t change between baseline and the final round.
A good answer names the lab, the methods and the chain of custody.
11. Which approvals and permits apply, and who files them?
Permits for underground injection vary by state [1]. Projects in state voluntary cleanup, RCRA or underground storage tank programs each answer to their own regulator [3], and introducing non-native microbes can raise questions of its own.
A good answer names the agencies and permits and who is responsible for each.
12. What does the contract guarantee, and what is the fallback?
Excavation is common where in-place methods won’t work fast enough, and a hot spot can be dug out alongside biological treatment [12]. The proposal should say what triggers that fallback and who pays.
A good answer ties payment to sampling milestones and states the endpoint. We’d be wary of any proposal guaranteeing a percentage removal or a finish date before the site has been characterized.
How Elm Dirt answers
| Question | Our answer |
|---|---|
| 1. Baseline | We start with sampling. |
| 3. Fit | We tell you when biology does not apply, including for metals. |
| 4. Treatability | We recommend one, with a nutrient-only comparison arm. |
| 6. Evidence | We cite peer-reviewed research on the species identified in our products, and we verify site results with independent lab testing. |
| 9. Timeline | Months to a year or more, verified by independent laboratory testing. |
| 12. Guarantees | We do not guarantee outcomes before a site assessment. |
Biome Makers, an independent lab, identified 291 microbial species in our Plant Juice. We work directly with applicators and can be on site.
The limits of a checklist
Twelve questions can’t predict whether a particular vendor will succeed. They show whether the vendor has done the thinking success requires. Run them past us.
Sources
- U.S. EPA. Green Remediation Best Management Practices: Bioremediation. EPA 542-F-21-028, December 2021. Link. Accessed 2026-10-01.
- U.S. EPA. Risk-Based Brownfields Cleanups. Link. Accessed 2026-10-01.
- U.S. EPA. Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites. EPA/625/R-06/015, October 2006. Link. Accessed 2026-10-01.
- Federal Remediation Technologies Roundtable. Remediation Technologies Screening Matrix, section 3.1: In Situ Biological Treatment for Soil, Sediment, and Sludge. Link. Accessed 2026-10-01.
- U.S. EPA. Guide for Conducting Treatability Studies Under CERCLA: Biodegradation Remedy Selection, Interim Guidance. EPA/540/R-93/519a, August 1993. Link. Accessed 2026-10-01.
- Szulc A, Ambrożewicz D, Sydow M, et al. The influence of bioaugmentation and biosurfactant addition on bioremediation efficiency of diesel-oil contaminated soil: feasibility during field studies. Journal of Environmental Management 132:121-128, 2014. doi:10.1016/j.jenvman.2013.11.006.
- Dybas MJ, Hyndman DW, Heine R, et al. Development, operation, and long-term performance of a full-scale biocurtain utilizing bioaugmentation. Environmental Science & Technology 36(16):3635-3644, 2002. doi:10.1021/es0114557.
- Pradeep V, Subbaiah UM. Repeated batch and continuous degradation of chlorpyrifos by Pseudomonas putida. Journal of Environmental Science and Health Part B 50(5):346-360, 2015. doi:10.1080/03601234.2015.1000180.
- Boonchan S, Britz ML, Stanley GA. Degradation and mineralization of high-molecular-weight polycyclic aromatic hydrocarbons by defined fungal-bacterial cocultures. Applied and Environmental Microbiology 66(3):1007-1019, 2000. doi:10.1128/AEM.66.3.1007-1019.2000.
- U.S. EPA. A Citizen’s Guide to Bioremediation. EPA 542-F-12-003, September 2012. Link. Accessed 2026-10-01.
- Lendvay JM, Löffler FE, Dollhopf M, et al. Bioreactive barriers: a comparison of bioaugmentation and biostimulation for chlorinated solvent remediation. Environmental Science & Technology 37(7):1422-1431, 2003. doi:10.1021/es025985u.
- U.S. EPA. A Citizen’s Guide to Excavation of Contaminated Soil. EPA 542-F-12-007, September 2012. Link. Accessed 2026-10-01.