Petroleum Guidance - Introduction
The Remediation Section within OPS is involved with the assessment and remediation of petroleum releases from regulated storage tank systems during the operation of such systems and even after their permanent closure. Assessments may indicate that either a suspected or a confirmed release has occurred. Suspected releases may be investigated with system tests or limited site checks to confirm or close the suspected release report.
In the event of a confirmed release of product from a regulated storage tank system, OPS requires that the system owner or operator follow regulations promulgated in the Colorado Code of Regulations (7 CCR 1101-14) that detail the necessary steps to fully assess and remediate the release to mitigate hazards to the environment and public safety and health. These regulations became effective on December 1, 1989, and were most recently revised on January 1, 2025.
Both the tank owner and tank operator are held equally responsible for proper tank system management.
The purpose of this guidance document is to assist owners and/or operators of regulated storage tank facilities and their consultants in conducting release investigations, performing initial response actions, preparing site characterization reports, and preparing and implementing corrective action plans to obtain release event closure. This document contains a summary of the necessary actions to be taken, and information that should be gathered to determine the extent and degree of contamination that exists in soil, surface water, groundwater, and/or soil vapor resulting from a leak, release, or spill associated with a regulated storage tank, including ancillary piping and/or delivery systems.
The guidance document is consistent with and augments the regulations, but does not supersede any of the regulations. OPS encourages owners/operators to re-evaluate existing assessment or corrective action projects under current regulations and to periodically review the progress of ongoing corrective actions.
OPS has adopted a formal method of risk evaluation based on the ASTM (American Society for Testing and Materials) Standard E1739, Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites. This will facilitate cost-effective protection of human health and the environment as well as consistency in the service we provide to the regulated community.
The standardized Colorado Risk-Based Corrective Action (RBCA) process incorporates established modeling techniques using current data on toxicological and chemical properties to estimate cleanup goals and predict contaminant fate and transport. RBCA utilizes a tiered approach, based on ASTM protocol, to set cleanup goals that are appropriate for each individual site. The initial Tier I site evaluation consists of comparing site concentrations of chemicals of concern (COCs) with a look-up table containing conservative risk based screening levels (RBSLs) for COCs in various media. If the site concentrations are below these Tier I RBSLs, no further site characterization or corrective action is required. Tier II, Tier III and Tier IV evaluations permit the incorporation of site-specific model input parameters to facilitate the development of cleanup goals that are customized to the individual site. The RBCA process objective is to eliminate all exposure pathways to potential receptors.
Questions regarding this document may be answered by calling the OPS Storage Tank Remediation Program Technical Assistance Line at 303-318-8547. Voicemail messages can be left 24 hours a day and will be returned during business hours (Monday-Friday, 8 AM to 5 PM, except federal or state holidays). Email queries are also welcome at cdle_technical_assistance@state.co.us.
The OPS website provides access to guidance documents, statutes, regulations, required report formats, additional program-related information, and contact information to locate experienced environmental consulting companies. See Appendix A for definitions of terms used in this guidance.
A Brief History
The Office of the State Inspector of Oils was created in 1899 and resided in the Department of Oil Inspection. Official reports from as early as 1913 indicate the Department of Oil Inspection was responsible for setting standards for the safe storage and sale of fuel products, tracking shipments of fuel in and out of Colorado, and collecting fuel taxes. In the mid-1900’s, there was a consolidation of state government in which many larger departments absorbed smaller departments. At that time, part of the Department of Oil Inspection was merged into CDLE as the Oil Inspection Section (OIS), while the other part related to fuel taxes was merged into the Department of Revenue.
In 1989, following the EPA’s (United States Environmental Protection Agency) implementation of regulations related to underground storage tanks (USTs) in December 1988, Colorado’s General Assembly adopted a comprehensive UST law through HB89-1299, which included enforcement of tank regulations, cleanup regulations, and administration of the PSTF. Since the OIS at CDLE historically had been effectively regulating fuel products, the General Assembly split the implementation of the new UST program between OIS at CDLE and the (then) Colorado Department of Health (CDH).
The OIS was given the responsibility for enforcement of tank regulations because of its historical responsibility for enforcing fire code regulations concerning petroleum storage tanks (underground and aboveground) and the retail sale of motor fuel products. OIS was also given partial responsibility for reviewing State Fund applications in the area of tank compliance.
The oversight of the cleanup of petroleum releases was assigned to the CDH because of their experience in dealing with environmental contamination. They were also given the overall responsibility of administration of the PSTF. The remedial action categories (RAC) for soil based on groundwater use were adopted as follows:
RAC I soils had to be remediated to less than 20 milligrams per kilogram (mg/kg) total benzene, toluene, ethylbenzene, and total xylenes (BTEX) and less than 100 mg/kg total petroleum hydrocarbons (TPH) where the groundwater was:
- currently being used as a public and/or private drinking water supply, or
- with the potential for use as a public and/or private drinking water supply, or
- within 500 feet or within the zone of influence of a private drinking water supply well.
RAC II soils had to be remediated to less than 50 mg/kg total BTEX and less than 250 mg/kg TPH where the groundwater was:
- with the potential for use as a private drinking water supply; or
- not included in the RAC I category.
RAC III soils had to be remediated to less than 100 mg/kg total BTEX and less than 500 mg/kg TPH where the groundwater was not being used and with little or no potential for being used as a public or private drinking water supply. RAC Ill was decided on a case-by-case basis.
The CDH was renamed Colorado Department of Public Health and the Environment (CDPHE) in 1994.
In 1995, significant backlogs on UST cleanup and unpaid reimbursement applications at CDPHE caused the General Assembly, through HB95-1183, to create efficiency by consolidating the administration of the entire Storage Tank Program by transferring CDH’s responsibilities to the OIS. Consolidation clarified release reporting requirements and allowed comprehensive communication between the inspection, remediation, and fund programs to promote quicker and more cost-effective cleanup.
In 1999, OIS adopted a RBCA (risk-based corrective action) program, allowing petroleum contamination to remain on a facility’s property (Tier II) in accordance with ASTM Standard E1739-95, and in response to EPA support for such actions (EPA, 1995). This program was expanded in 2015 to include Tier III and IV closure criteria for contamination at offsite properties. EPA highlighted the OPS RBCA program in November 2020.
In 2001, the General Assembly, through HB01-1373, created the OPS within CDLE by consolidating the OIS with other CDLE public safety programs (boiler inspection, explosives, public school construction, and carnival and amusement parks) that were also focused on worker protection. The purpose of this legislation was to create efficiency through consolidation of administration.
In 2007, the General Assembly established statewide regulation of conveyances through the Elevator and Escalator Certification Act (SB07-123) and delegated this new program to OPS. In 2009, the General Assembly, through HB09-1151, moved the Public School Construction Program at OPS to the Division of Fire Safety’s Public School Construction Program in the Department of Public Safety. In 2014, the General Assembly established statewide regulation of retail natural gas facilities through HB 13-1110 and delegated this new program to OPS. In 2016, the General Assembly established statewide regulation for retail hydrogen fueling facilities through HB 16-1053 and also delegated this new program to OPS. In 2018, the General Assembly assigned the Underground Damage Prevention Safety Commission to OPS.