Petroleum Guidance - List of Appendices

Abandoned tank

An underground or aboveground petroleum storage tank that the current tank owner or operator or current property owner did not install, has never operated or leased to another for operation, and had no reason to know was present on the site at the time of site acquisition.

Aboveground storage tank (AST)

Any one or a combination of containers, vessels, and enclosures, including structures and appurtenances connected to them, constructed of non-earthen materials, including but not limited to concrete, steel, or plastic, which provide structural support, used to contain or dispense fuel products and the volume of which, including the pipes connected thereto, is ninety percent or more above the surface of the ground, is not permanently closed, and except those exempted in statute and these regulations.

Advancing plume

Where the solute plume margin is continuing to move outward or downgradient from the source area.

Bulk plant

The portion of a property where liquids are received by tank vessel, pipelines, tank car, or tank vehicle and are stored or blended in bulk for the purpose of distributing such liquids by tank vessel, pipeline, tank car, tank vehicle, portable tank or container.

Calendar days

Consecutive days including weekends and nationally recognized holidays.

Code of Federal Regulations (CFR)

The codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government

Chemicals of concern (COCs)

Chemical compounds that have been identified for evaluation due to specific risks to human health and/or the environment.

Committee

Petroleum Storage Tank Committee (PSTC) created in C.R.S. § 8-20.5-104.

Containment sump

A liquid-tight container that protects the environment by containing leaks and spills of regulated substances from piping, dispensers, pumps, and related components in the containment area. Containment sumps may be single-walled or secondarily contained and located at the top of tank (tank top or submersible turbine pump sump), underneath the dispenser (under-dispenser containment sump), or at other points in the piping run (transition or intermediate sump).

Contamination

The presence of a regulated substance at or below ground that originated from a regulated storage tank system.

Decay (attenuation) rate

The measured reduction in concentration or mass of a compound with time expressed as an amount of reduction per unit time.

Dispenser

Equipment that dispenses regulated substances from the storage tank system.

Director

The Director of the Division of Oil and Public Safety of the Colorado Department of Labor and Employment or any designees thereof which may include certain employees of the Division of Oil and Public Safety of the Colorado Department of Labor and Employment or other persons.

Downgradient

Is in the direction of maximum decreasing static head.

Electron acceptors

Elements or compounds that are reduced by receiving electrons produced by the oxidation of organic compounds through microbial metabolism or abiotic chemical oxidation processes.

Excavation zone

The volume containing the UST system and backfill material bounded by the ground surface, walls, and floor of the pit and trenches into which the UST system is placed at the time of installation.

Exposure pathway

The course that a chemical of concern takes from a source area to a point of exposure. An exposure pathway describes a unique mechanism by which a person or sensitive environment is assumed to be exposed to a chemical of concern. Each exposure pathway includes a source, an exposure route, and a point of exposure. If the exposure point differs from the source, transport or exposure media (e.g., air, water, dust) are also included. All exposure pathways are assumed to be complete unless an exposure pathway elimination criteria is demonstrated. Exposure pathway elimination criteria are listed in the Owner/Operator Guidance Document.

Fund

Petroleum Storage Tank Fund (PSTF) created in C.R.S. § 8-20.5-103.

Hydraulic conductivity

The coefficient of proportionality describing the rate at which water can move through a permeable medium.

Hydraulic gradient

The slope of the water table in the direction of groundwater flow. This slope is typically expressed as a unit change in water table elevation per unit horizontal distance (e.g. ft/ft).

Imminent threat to human health or safety or the environment

A condition that creates a substantial probability of harm, when the probability and potential extent of harm make it reasonably necessary to take immediate action to prevent, reduce, or mitigate the actual or potential damages to human health or safety or the environment.

Light non-aqueous phase liquid (LNAPL)

A regulated organic liquid, such as gasoline or diesel fuel, that exists as a separate phase and is less dense than water and immiscible in water.

Media

Intervening substances through which something is transmitted or carried (e.g. soil, water, or air).

Milestones

Projected concentrations over time at in-plume wells. Milestones are used as indicators that degradation of contaminants is occurring at the projected decay rate. 

Natural attenuation

The reduction in mass or concentration of a compound over time or distance from the source due to naturally occurring physical, chemical and biological processes, such as biodegradation, dispersion, dilution, sorption, and volatilization.

Non-responsible Party

A party that never owned, operated, leased, or managed the regulated substance system at the time of the release.

Plume

A volume of groundwater where chemicals of concern are present. 

Operator

Any person in control of, or having responsibility for the daily operation of an underground or aboveground storage tank system.

Orphaned tank

An underground storage tank that was not closed,  the O/O is unidentified, and the property changed ownership prior to December 22, 1988.

Overfill

A release that occurs when a tank is filled beyond its capacity, resulting in a discharge of the regulated substance to the environment.

Owner

1. In the case of an underground storage tank in use on or after November 8, 1984, or brought into use after that date, any person who owns an underground storage tank system used for the storage, use, or dispensing of regulated substances;
2. In the case of an underground storage tank system in use before November 8, 1984, but no longer in use on or after November 8, 1984, any person who owned such tank immediately before the discontinuation of its use; or
3. Any person who owns an aboveground storage tank.
4. Regarding reporting and responding to releases of regulated substances, Owner means the person who owned the tank system at the time of the release. The term “owner” does not include any person who, without participating in the management of an underground storage tank and otherwise not engaged in petroleum production, refining, and marketing, holds indicia of ownership primarily to protect a security interest in or lien on the tank or the property where the tank is located.

Owner(s)/operator(s)

Either the facility owner or the operator. If neither the owner nor the operator performs a task, both shall be in violation of these regulations. Duplication of the task is not required.

Petroleum

Crude oil or any fraction thereof that is liquid at standard conditions of temperature and pressure (60 degrees Fahrenheit and 14.7 pounds per square inch absolute).

Point of compliance (POC)

A location or locations selected between the source area(s) and potential point(s) of exposure where concentrations of chemicals of concern must be at or below the determined groundwater target levels. 

Point of exposure (POE)

The location at which a person or sensitive environment is assumed to be exposed to a chemical of concern. POEs include property boundaries, surficial soils, subsurface utilities, structures, groundwater wells, surface water, and sensitive environments. POEs for MTBE, 1,2 DCA, and EDB are limited to water supply wells and surface water features that are used for human consumption.

Regulated substance

UST systems has the same meaning as in C.R.S. § 8-20.5-101(13) as follows:

1. Any substance defined in Section 101 (14) of the federal “Comprehensive Environmental Response, Compensation, and Liability Act of 1980”, as amended, but not including any substance regulated as a hazardous waste under subtitle (C) of Title II of the federal “Resource Conservation and Recovery Act of 1976”, as amended.
2. Petroleum, including crude oil or any fraction thereof, that is liquid at standard conditions of temperature and pressure (60 degrees Fahrenheit and 14.7 pounds per square inch absolute).
3. Alternative fuel
4. Renewable fuel

AST

Regulated fuel products as defined in C.R.S. § 8-20.5- 101(6), including alternative fuels and renewable fuels as defined in CRS 8-20.5-101(2.5) and (14.5) as follows:

1. All gasoline, aviation gasoline, diesel, aviation turbine fuel, jet fuel, fuel oil, biodiesel, biodiesel blends, kerosene, all alcohol blended fuels, gas or gaseous compounds, and other volatile, flammable, or combustible liquids, produced, compounded, and offered for sale or used for the purpose of generating heat, light, or power in internal combustion engines or fuel cells, for cleaning or for any other similar usage.
2. Alternative fuel
3. Renewable fuel

Release

Any spilling, leaking, emitting, discharging, escaping, leaching, or disposing of a regulated substance from a regulated tank system into the environment.

Remediation

Actions taken to reduce concentrations of chemicals of concern (including natural attenuation), or prevent migration of chemicals of concern to POEs. Remediation shall be implemented for sites where no further action is not appropriate.

Responsible Party

Owner/operator of the regulated substance system at the time of the release.
Risk-based corrective action (RBCA)

A consistent decision-making process for the assessment and response to a petroleum release, based on the protection of human health and the environment according to ASTM 1739.
 

Sensitive environment

An area of particular environmental value where regulated petroleum contamination could pose a greater threat than in other less sensitive areas. Sensitive environments include: critical habitat for federally endangered or threatened species, national parks, national monuments, national recreation areas, national wildlife refuges; national forests, campgrounds; recreational areas, game management areas, wildlife management areas, designated federal wilderness areas, wetlands, wild and scenic rivers, state parks, state wildlife refuges, habitat designated for state endangered species, fishery resources, state designated natural areas, wellhead protection areas, classified groundwater areas, and county or municipal parks.

Shrinking plume

A configuration where the solute plume margin is receding over time and the concentrations at points within the plume are decreasing over time.

Source

The portion or component of a tank system that allows hydrocarbons to enter the environment.

Site check

Collecting soil and/or groundwater samples for laboratory analysis from locations most likely to demonstrate the presence of a release from a regulated storage tank system.

Source area

The location of free phase liquid hydrocarbons or the location of highest soil and groundwater concentrations of constituents of concern. Usually located near the source (of the release).

Source concentration

The highest concentration, in soil and/or groundwater and /or vapor, of the chemicals of concern.

Stable plume

Where the solute plume margin is stationary over time and the concentrations at points within the plume are relatively uniform over time or may decrease over time.

Subsurface soils

All soils located at a depth of greater than one meter below the ground surface.

Surficial soils

All soils located from the ground surface to a depth of one meter below the ground surface.

System test

A test of tank system components, including any associated delivery piping, secondary containment, or spill control component, to identify releases of regulated substances. Specifically, for underground tanks, underground piping, spill prevention equipment, and containment sumps. Owners and operators must conduct tests according to the requirements for tank tightness testing (2-3-4-2(c)), line tightness testing (2-3-4-3(a)(2)(i)), and spill prevention equipment and containment sumps (2-3-5(a)).

Temporary closure

A period of time that a storage tank is empty but is not permanently closed or has not changed service to store a non-regulated substance. This term does not apply when a tank system is emptied for repair.

Tier I risk-based screening levels (RBSLs)

The default maximum concentrations for COCs used to determine whether remediation (cleanup) is required.

Tier II site-specific target level(s) (SSTLs)

The risk-based remedial action target levels for COCs developed for a particular site using site-specific geological and hydrogeological data in a predictive model.

Tier III closure criteria

Establishes conditions where all exposure pathways have been eliminated, even though contamination remains above Tier I RBSLs beyond the release property boundary and beneath, but not beyond the adjoining public roadway.

Tier IV closure criteria

Establishes conditions where all exposure pathways have been eliminated, even though contamination remains above Tier I RBSLs beyond the release property boundary irrespective of land use and where no storage tanks remain on the release property.

Under-dispenser containment (UDC)

Containment underneath a dispenser that will prevent leaks from the dispenser and piping within or above the UDC from reaching soil or groundwater.

Underground storage tank (UST)

Any one or combination of tanks, including underground pipes connected thereto, except those exempted in statute and these regulations, that is used to contain an accumulation of regulated substances and the volume of which, including the volume of underground pipes connected thereto, is ten percent or more beneath the surface of the ground and is not permanently closed.

Working days

Consecutive days, excluding weekends and nationally-recognized holidays.