More Bad News for California Dry Cleaner Remediation and Redevelopment Projects

6/12/2024

By Matt Winefield

California has, by far, the most stringent, overly-conservative dry cleaner subsurface remediation standards. Golden State properties will remain blighted until better science is used as is the case with 49 other States.

I spend a fair amount of time railing on California regulators about overly-conservative remediation standards that are impeding commercial and residential development. So, why stop now?! Let’s get right to it . . .

If you are trying to redevelop above a contaminated former or existing dry cleaner site in The Golden State, you are operating under the nation’s most stringent remediation standards for groundwater, soil gas, and indoor air for the primary chemical of concern, tetrachloroethylene (PCE). This data is encapsulated succinctly in the graphs below for the three media.

This data and remaining references have all been obtained from the analysis entitled: “Overview of State Approaches to Vapor Intrusion: 2023 Update,” Groundwater Monitoring & Remediation, Bart Eklund, et al. (2024). For each State, the review includes tabulations of the available types of screening values (e.g., soil gas, groundwater, and indoor air), the screening values for selected chemicals that commonly drive vapor intrusion investigations for selected volatile organic compounds, and the basis of risk levels used for cancer and non-cancer risk.

In short, for soil gas, groundwater and indoor air, California expects remediation to be completed to concentrations 2 or 3 orders of magnitude less than the vast majority of other States. The driver of most dry cleaner remediation projects is the ability to remove PCE in soil vapor. So, let’s examine the residential screening levels for shallow soil gas concentrations. (Reference Table 4 in Eklund, et al.) California has a residential screening value of 15 ug/m3. The average (mean) for the 50 states is 5,245 ug/m3. While there are some outliers, a significant majority of the states enforce shallow soil screening levels in the high 100s or low 1000s.

So, what can we conclude from this data analysis? Might it be all of the following: 1) California is the only State with brilliant health scientists and all the other States have erred; and 2) all other States are indiscriminately jeopardizing the health of its citizens; and 3) one should only live above a remediated former dry cleaner if one resides in California.

OR might we conclude: A) California regulators are wasting much-needed resources on removing residual molecules of PCE soil vapors, which scientists contend should remain in place; and B) California’s screening values are making it even more cost prohibitive to build desperately needed housing on dry cleaner and other commercial lots; and C) California regulators cannot show that their stringent standards are providing health benefits when compared to the 49 other States.

Is it 1/2/3 or A/B/C? This author contends it is A/B/C. Shame on CalEPA, SWRCB, and DTSC for impeding housing development in the face of science that relaxes PCE screening values now being mandated via the California Supplemental Vapor Intrusion Guidance Document (February 2024).