Skip to main content

Fact Sheet 1: Introduction

1. What is TACO?

The Tiered Approach to Corrective Action Objectives regulations (TACO-35 Ill. Adm. Code Part 742) provide Illinois EPA's Bureau of Land (BOL) programs a method to develop site-specific remediation objectives for contaminated soil and groundwater. These remediation objectives protect human health and take into account site conditions and land use. Remediation objectives generated by TACO are risk-based and site-specific.

2. How can TACO help me?

Previously, BOL used conservative "one-size-fits-all" remediation objectives at nearly every site. Baseline remediation objectives still exist, but other options also protective of human health have been added.


TACO provides flexibility to site owners and operators in developing site-specific remediation objectives. It's now the site owners and operators who decide how best to manage their sites within TACO guidelines. However, this determination of site-specific remediation objectives is subject to Illinois EPA review and approval.


By exercising these new choices, site owners and operators may reduce remediation costs, return more sites to productive use, hasten property redevelopment, and still fully comply with environmental laws and regulations.


Under TACO, a site may qualify to receive a No Further Remediation Letter acknowledging the site owner or operator has satisfied the applicable BOL program requirements (See  Fact Sheet 3) .

3. Does TACO apply to my site?

Yes, you will use TACO if your site is regulated by one of the following BOL programs:


4. Are there any limitations to TACO?

TACO works in cooperation with the existing laws and regulations. If you participate in one of the BOL programs listed above, TACO can only be used in conjunction with that program's statutory and regulatory requirements.


Because of the wide range of programs in which TACO can be applied, TACO itself does not provide procedures for characterizing a site and the potential contamination at the site. Such characterization is a critical step in the overall TACO process, but is program specific.


Consistent with the regulations of other programs, and as approved by Illinois EPA, TACO may also be used to develop remediation objectives to protect surface waters, sediments, or ecological concerns.


Any TACO procedure that delays an owner's or operator's response during an environmental emergency cannot be used.


TACO does not consider any person's liability, culpability, or legal, moral or ethical responsibility to address a release of a regulated substance into the environment.

5. Can I use TACO to update my existing remediation objectives?


6. How does TACO work?

TACO offers site owners and operators the following choices:


  • Exclusion of exposure routes
  • Use of area background concentrations as screening tools or remediation objectives
  • Three tiers for selecting remediation objectives.

Selection of an option or combination of options to use in developing remediation objectives depends on the site-specific conditions and the site owner's or operator's remediation goals.

7. Exposure Route Evaluations

Human exposure route(s) can be excluded from further consideration provided the requirements in Subpart C of TACO are met. The human exposure routes are: inhalation, soil ingestion and groundwater ingestion (including migration to groundwater). Exclusion of an exposure route will require an institutional control  (See  Fact Sheet 4 &  Fact Sheet 8) .

8. Determining Area Background

When contaminant concentrations do not exceed background concentrations for soil and/or groundwater, evaluation under any of the other tiers may not be required. The procedures for determining area background concentrations are contained in Subpart D of TACO (See  Fact Sheet 9) .

9. Tier 1

In Tier 1, the site owner or operator compares site sample analytical results to baseline remediation objectives, contained in "look-up" tables. These objectives are based on simple, conservative models (See  Fact Sheet 6). To complete a Tier 1 evaluation, the site owner or operator must know:


  • The extent and concentrations of the contaminants of concern,
  • The groundwater classification as defined in 35 Illinois Administrative Code, Part 620, and
  • The intended land use at the site (either residential or industrial/commercial).

If remediation objectives are based on an industrial/commercial land use, then an institutional control prohibiting the property from residential use will be imposed.

10. Tier 2

A Tier 2 evaluation is not required for those contaminants of concern that meet the Tier 1 remediation objectives (See  Fact Sheet 7 &  Fact Sheet 10). A Tier 2 evaluation is also not required for exposure routes excluded under Subpart C of TACO. Under Tier 2, a site owner or operator considers the:


  • Data previously gathered for Tier 1,
  • Physical and chemical properties of the contaminants,
  • Site-specific soil and groundwater parameters (e.g., soil type, soil organic carbon content, hydraulic conductivity), and
  • Application of institutional controls and engineered barriers.

The additional Tier 2 information can potentially allow for the calculation of less stringent but equivalently protective remediation objectives. These calculations are derived from simple analytical models and standardized equations.

11. Tier 3

Site owners and operators can use Tier 3 to address those situations outside of Tier 1 and Tier 2. These situations can range from simple sites where physical barriers limit remediation, to complex sites where full-scale risk assessments or alternative modeling are applied. A Tier 3 review and evaluation draws on expertise beyond the immediate BOL project manager.

12. Do I have to use all three tiers?

No. The tier(s) you select to develop remediation objectives will depend on multiple factors, including the actual amount and extent of contamination present, the cost of remediating that contamination, and the cost of obtaining the information necessary to conduct a Tier 2 or Tier 3 analysis. The tiers do not need to be used in sequence.

13. What happens next?

After remediation objectives are established using TACO procedures, a site owner or operator may:


  • Reduce contaminant concentrations to meet established objectives through active remediation (e.g., dig and haul, or treatment in place),
  • Restrict exposure to contaminated soil or groundwater or both by using engineered barriers and/or institutional controls,
  • Take no action, if contaminant concentrations present at the site do not exceed remediation objectives, or
  • Use any combination of the options above.