California Water Boards' Annual Performance Report - Fiscal Year 2022-23 

TECHNICAL CONSIDERATIONS

GLOSSARY

Leaking Underground Storage Tanks
Leaking underground storage tanks (UST) are a significant source of petroleum impacts to groundwater and a risk to human health and safety. Contamination may impact drinking water aquifers and public or private drinking water wells, and present a risk of exposure to humans through inhalation of vapors. These threats are minimized when UST owners or operators (responsible parties) report an environmental leak to a local regulatory agency within 24 hours of detection. If a leak occurs, responsible parties or their representative must notify the appropriate Regional Water Quality Control Board or County Agency and submit an unauthorized release form. Site investigation and cleanup (corrective action) costs can only be reimbursed by the Cleanup Fund after the tank release has been reported. Regional Board and many County Agencies are authorized to oversee the investigation and cleanup of UST system releases.

Low-Threat Underground Storage Tank Case Closure Policy
This policy is a state policy for water quality control and applies to all petroleum UST sites subject to Chapter 6.7 of Division 20 of the Health and Safety Code and Chapter 16 of Division 3 of Title 23 of the California Code of Regulations.

Site Cleanup
The Site Cleanup program addresses commercial, industrial, and other non-military sites with non-fuel contamination. Many of these sites are considered Brownfields because of their reuse potential. Site Cleanup Requirements generally mandate a schedule for specific tasks that must be performed by the responsible party(ies) to investigate and clean up the site. Water Board staff oversee implementation of these tasks including investigations, corrective actions, and human health risk assessments at sites with current or historic unauthorized discharges which have, or threaten to adversely affect waters of the state.

Procedures for site investigation and remediation are promulgated in State Water Resources Control Board Resolution No. 92-49 titled Policies and Procedures For Investigation and Cleanup and Abatement of Discharges Under Water Code Section 13304. Responsible parties conduct the following work: preliminary assessment, soil and water investigation, interim remedial measures if warranted, risk assessment, cleanup goals setting, cleanup planning, cleanup implementation, and monitoring. Most often, responsible parties conduct the work voluntarily, but sometimes enforcement orders are necessary to compel the work to be performed.

Military Sites - Department of Defense Program
Decades of defense activities have degraded water quality on and around federally-owned facilities. Agreements with the Department of Defense provide for accelerated cleanups at military bases and other Defense sites scheduled for closure and reuse. Site investigation and cleanup procedures are consistent with State laws and regulations as well as applicable provisions of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) which guides the federal Superfund program.

Case Closure
A site qualifies to receive a "No Further Action" (closure) letter once the owner or operator meets all appropriate corrective action requirements. Once this occurs, the county agency or regional board will inform the responsible party in writing that no further work is required.

Active Remediation
Active remediation comprises the phase(s) of work where the construction or implementation of activities to accomplish cleanup at a site occurs. This includes interim remedial cleanup actions and final remedial cleanup actions intended to substantially address site pollution, and monitored natural attenuation, if that was the result of a remedy-selection process (e.g. through an approved CAP/RAP). It does not include pilot studies for remedies being considered, nor "monitor only" cases that have not gone through the remedy selection process.

Number of cleanup cases with human health exposure controlled
A count of all open Water Board-lead cases and Shared-lead cases where human health exposure has been evaluated as of the end of the Fiscal Year.

Number of cleanup cases groundwater contaminant migration under control
A count of all open Water Board-lead cases and Shared-lead cases where groundwater contaminant migration has been evaluated as of the end of the Fiscal Year.