It’s only been a month since the first 2025 ESL changes were sent out from the CA San Francisco Water Board and we’ve already had two revisions!
The first revision addressed corrections to the Vapor (Soil Gas and Indoor Air) Summary Table.
This second revision brings a few changes to several areas of the Summary Tables which I have listed below. I also want to note differing BTEX values from the 2019 revision to 2025 that I did not highlight in my previous post.
What’s BTEX?
BTEX is short for a group of four volatile organic compounds commonly found in gasoline – Benzene, toluene, ethylbenzene, and xylenes. These are some of the more common compounds that we focus on in Environmental Due Diligence.
In the 2025 revision we see slight changes in Benzene and Toluene, although ethylbenzene and xylene remain the same.
2019 Values:
| Chemicals | CAS No. | Groundwater (μg/L) |
Soil3 (mg/kg) |
Subslab/Soil Gas
(μg/m3) |
Indoor Air (μg/m3) |
| Benzene | 71-43-2 | 4.2E-01 | 2.5E-02 | 3.2+00 | 9.7-02 |
| Toluene | 108-88-3 | 4.0E+01 | 3.2E+00 | 1.0E+04 | 3.1E+02 |
2025 Values:
| Chemicals | CAS No. | Groundwater (μg/L) |
Soil3 (mg/kg) |
Subslab/Soil Gas
(μg/m3) |
Indoor Air (μg/m3) |
| Benzene | 71-43-2 | 4.3E-01 | 2.5E-02 | 3.2+00 | 9.7-02 |
| Toluene | 108-88-3 | 4.0E+01 | 3.2E+00 | 1.5E+04 | 4.4E+02 |
Other changes in this revision:
- The construction worker soil ESL value for lead was input incorrectly in the ESL Workbook and Summary Tables and has been corrected. 2. 2.
- Updated equations for the direct exposure soil ESLs were mistakenly not used for all chemicals in the Workbook. The Workbook has been corrected, and the updated ESL values have been transferred to the Summary Tables. 3. 3
- The soil saturation concentrations (Csat) for the petroleum mixture (e.g., gasoline, diesel) ESLs were input incorrectly. The Workbook has been corrected, and the updated ESL values have been transferred to the Summary Tables.
If you have more questions or want to check out these changes yourself, please contact RB2-ESLs@waterboards.ca.gov or checkout the San Francisco Bay Regional Water’s Environmental Screening Level (ESL) documents posted here.
References:
San Francisco Bay Regional Water Quality Control Board. Site Cleanup Program: Screening Levels and Guidance. California Water Boards, n.d., https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/sitecleanupprogram.html#screeninglevelsandguidance. Accessed 18 Aug. 2025.