Fact Sheet 6: Tier 1

What is Tier 1?

A Tier 1 evaluation compares the concentrations of contaminants of concern detected at a site to baseline remediation objectives. Tier 1 enables site owners to choose between residential and industrial/commercial use of a site; however, institutional controls are required whenever remediation objectives are based on an industrial/commercial land use.

Tier 1 provides the following pre-calculated "Look Up" Tables:

  • Residential Soil Remediation Objectives (Appendix B, Table A)

  • Industrial/Commercial Soil Remediation Objectives (Appendix B, Table B)

  • Groundwater Remediation Objectives (Appendix B, Table E)

  • pH specific Soil Remediation Objectives for Inorganics and Ionizing Organics for the Migration to Groundwater Portion of the Groundwater Ingestion Route (Appendix B, Tables C & D)

It is important to check the footnotes in the Tier 1 tables. For instance, footnote "e" means the chemical is a carcinogen; footnote "b" means the chemical is not a carcinogen. Footnote "m" means the objective is expressed as a TCLP or SPLP value.

When do I use Tier 1?

After you've completed a site investigation or characterization, you should compare your sample results to the Tier 1 "Look Up" Tables. Tier 1 can serve as a screening tool, or can be used as your remediation objectives.

Note: Before beginning a Tier 1 analysis, you may want to consider a pathway exclusion evaluation (See Fact Sheet 8).

How do I use Tier 1?

For soil, a Tier 1 remediation objective is obtained from the "Look Up" Tables for:

  • Inhalation,

  • Ingestion, and

  • Migration to Groundwater (also called the Soil Component of the Groundwater Ingestion Exposure Route)

Of the three exposure routes, the most restrictive becomes your site's soil objective -- unless that particular route has been excluded from further consideration under the requirements of 742, Subpart C (See Fact Sheet 8).

For groundwater, the Tier 1 remediation objectives for your site correspond to the site's groundwater classification, either Class I or Class II. If no site-specific information is available, then the groundwater at the site is assumed to be Class I.

A contaminant is not of concern if the concentration of the contaminant is below the Tier 1 objective for the most restrictive route.

Is my site Residential or Industrial/ Commercial?

"Residential Property" is any real property that is used for habitation by individuals or properties where children have the opportunity for exposure to contaminants through ingestion or inhalation at educational facilities, health care facilities, child care facilities or playgrounds.

"Industrial/Commercial Property" is any real property that does not meet the definition of residential property, conservation property or agricultural property.

Whenever using the industrial/commercial scenario, the Construction Worker Scenario must also be evaluated. If the construction worker objectives are more stringent than the industrial/commercial objectives, the construction worker objectives apply.

The construction worker scenario is designed for workers performing demolition, earth moving or construction activities, as well as routine and emergency utility installation or repair.

Sites that meet Tier 1 residential remediation objectives do not need to be evaluated for the construction worker population.

What if my contaminant is not listed in the Tier 1 tables?

For contaminants not listed in the Tier 1 tables, you may request site-specific soil and groundwater remediation objectives from the BOL, or you can propose remediation objectives for BOL approval.

How many analytical samples do I need to collect for a Tier 1 evaluation? What do I analyze these samples for?

Site investigation and characterization requirements are program- and site-specific. Any averaging and/or compositing used in such an investigation must be consistent with the approach described in Section 742.225 (See Fact Sheet 10)

For Leaking Underground Storage Tank (LUST) sites, the indicator contaminants for unleaded gasoline are benzene, ethylbenzene, toluene and xylene.

For Site Remediation Program (SRP) sites, either a focused or comprehensive determination can be requested. A focused determination is designed for only a limited number of chemical(s). A comprehensive determination is for all recognized environmental conditions and their related contaminants of concern. A comprehensive determination usually requires sampling analyses for volatiles, semi-volatiles, and metals, but may also include agrichemicals, PCBs, and dioxins (See Fact Sheet 12).

For RCRA sites, the sampling analysis is usually determined by the constituents of the wastes managed in the RCRA unit and their degradation products. However, in certain cases, expanded lists of hazardous constituents must also be analyzed for.

What does it mean if my site's sample results are all below the Tier 1 values?

If you have met the Tier 1 values as well as all program specific requirements, including proper characterization of the site, then you qualify to receive a No Further Remediation letter (See Fact Sheet 3).

Tier 1 Example - Application of the Tier 1 Residential Table

In this example, the groundwater classification at the residential site is Class I. Assume no routes are excluded from consideration, pursuant to 742, Subpart C. The benzene and benzo(a)pyrene soil and groundwater remediation objectives obtained from Part 742, Appendix B, Tables A and E are:

 

Ingestion
(mg/kg)

Inhalation
(mg/kg)

Migration to
Groundwater
(mg/kg)

Groundwater
(mg/L)

Benzene

22

0.8

0.03

0.005

Benzo(a)Pyrene

0.09

---

8

0.002

The benzene soil remediation objective is 0.03 mg/kg, which is the most restrictive soil remediation objective. The groundwater remediation objective is 0.005 mg/L, due to the groundwater classification.

The benzo(a)pyrene soil remediation objective is 0.09 mg/kg, which is the most restrictive soil remediation objective. For contaminants such as benzo(a)pyrene, under Tier 1, the lack of an inhalation remediation objectives is not likely to underestimate risks. The benzo(a)pyrene groundwater remediation objective is 0.002 mg/L, due to the groundwater classification.

In another example, assume the ingestion of groundwater is excluded from consideration, pursuant to Subpart C. The benzene remediation objectives from Appendix B, Table C for Industrial/Commercial and Construction Worker Populations are: 200 mg/kg Ind/Com Ingestion, 4,300 mg/kg Construction Ingestion, 1.5 mg/kg Ind/Com Inhalation, and 1.7 mg/kg Construction Inhalation. The benzene soil remediation objective at this industrial/commercial site is 1.5 mg/kg because it is the most restrictive.