Administrative controls are changes in work procedures such as written safety policies, rules, supervision, schedules, and training with the goal of reducing the duration, frequency, and severity of exposure to hazardous chemicals or situations. They are one component the Industrial Hygiene program uses to protect tank farm workers. 

Administrative controls are established based on Chemicals of Potential Concern (COPCs). COPCs are chemicals that have been identified in the tank farm headspaces, and classified according to their carcinogenicity, concentration compared to their Occupational Exposure Limits, prevalence in tanks and toxicity.

Two types of administrative controls established by WRPS are Vapor Control Zones and Vapor Reduction Zones.


Vapor Control Zones (VCZ)

An administrative control boundary established where farm COPCs have the potential to exceed a respective action limit (AL) utilizing an appropriate evaluative method (e.g., 95th percentile of sample distribution, maximum individual sample result, etc.). The VCZ boundary is to be identified using a physical barrier and signage.


Vapor Reduction Zones (VRZ)

An administrative notification boundary established to inform personnel of activities that may result in increased vapors or odors not expected to exceed a respective action limit (AL). The VRZ boundary is to be identified using signage.


Action Limit (AL)

The airborne exposure concentration of a chemical contaminant above which exposures will be controlled. If an action level is not established by regulation, an action level is established at 50% of the 8-hour Time Weighted Average (TWA) of the Occupational Exposure Limit.

Defining the Unrestricted Work Boundary

TOC-IH-58451, March 28, 2018, Industrial Hygiene Basis for Defining the Unrestricted Work Boundary, Rev. 0.

The Washington River Protection Solutions (WRPS) Industrial Hygiene (IH) Department released a white paper on the IH basis for defining the Unrestricted Boundary related to tank farm vapors at Hanford. The Unrestricted Boundary will be established where practical at a tank farm fence line. The area from the Unrestricted Boundary to the Hanford Site Boundary will be considered the unrestricted area for which general workers or members of the public (with escort) can be assured that they will not be exposed to tank vapor hazards at levels that could place them at risk of exceeding an occupational exposure limit (OEL). Inputs to defining the Unrestricted Boundary included tank farm source data, dispersion modeling, stack and fence line monitoring, and IH rounds and routines, in addition to regulations governing the Tank Farms Operation Contract (TOC). The white paper also defines work boundaries within and outside of the Unrestricted Boundary that will be used moving forward within the IH program, including Exclusion Zone (EZ), Contamination Reduction Zone (CRZ), Support zone, and Industrial Zone. For the full text, please follow this link.

Industrial Hygiene monitoring strategy

Here is an example of an Industrial Hygiene monitoring strategy demonstrating VRZs