Decreasing Groundwater Contaminant Plume
During the reasonable timeframe when residual contamination is naturally reduced to cleanup goals, the groundwater contamination plume must be decreased. Future plume stability is established at the time of closure by showing that the residual contaminant plume in groundwater is decreasing. As a result of a decreasing contaminant plume, risk management measures are not necessary and the site does not require future SWRCB oversight, another requirement for low-threat PCE case closure.
Criteria: Establish that the residual contaminant plume in groundwater is decreasing.
It must also be established that during the reasonable timeframe, the remaining contamination:
- Cannot pose a risk to human health due to vapor intrusion or direct contact,
- Cannot pose a risk to the environment or deeper water-bearing zones, and
- Cannot pose any nuisance conditions.
These conditions must be established in such a manner that any risk management measures necessary are shown to work, implementation of risk measures are documented, and future SWRCB oversight is not required.
Criteria: Establish that either in post-cleanup or with post-cleanup risk management not requiring SWRCB oversight:
1) vapor intrusion or direct contact with residual contamination will not occur;
2) residual contamination will not risk the environment or travel to lower water-bearing zones, and
3) residual contamination will not cause a nuisance condition.
Consult with Our Experts for Low Threat PCE/Solvent Case Closure
We reviewed low-threat PCE solvent case closure as outlined in California’s Assessment Tool for Closure of Low-Threat Chlorinated Solvent Sites and developed three general criteria for case closure. If you are interested in low-threat PCE/solvent case closure for your site, we have over 40 years of experience. Call (831) 475-8141 or click on the button below for a free consultation.