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Shoshone-Bannock Tribes Waste Management Act


Soil Cleanup Standards for Contaminated Properties


JUNE 2, 2010

DRAFT FOR PUBLIC REVIEW AND COMMENT


The Fort Hall Business Council has approved this document for public review and comment for a 30 day period. All written comments are due on or before July 9, 2010.
All written comments on this document may be mailed or delivered to:
Shoshone-Bannock Tribes C/O Tribal Attorney Office, P.O. Box 306 Fort Hall, ID 83203
Attention: Environmental Waste Management Program REVISION (1) April 15, 2010


RESOLUTION
Whereas, the Tribal Land Use Environmental Waste Management Program Manager, Kelly Wright approached the Business Council to request approval for adoption and enact the Shoshone-Bannock Tribes Environmental Waste Management Program Soil Cleanup Standards for Contaminated Properties revised April 15, 2010;

WHEREAS, the Shoshone-Bannock Tribes (Tribes) have submitted proposed cleanup standards to supplement the Tribal Waste Management Act for public commit on two prior occasions; and Whereas, the Tribes have reconciled those public comments and made certain amendments to the cleanup standards;

NOW, 'THEREFORE, BE IT RESOLVED BY THE BUSINESS COUNCIL OF THE SHOSHONE-BANNOCK TRIBES, that the Tribal Land Use Environmental Waste Management Program Manager, Kelly Wright request is hereby approved and adopts the Shoshone-Bannock Tribes Environmental Waste Management Program Soil Cleanup Standards for Contaminated Properties Revised April 15, 2010 effective immediately subject to a thirty (30) day additional public comment period.

Authority for the foregoing resolution is found in the Indian Reorganization Act of June 18, 1934 (48 Stat., 984), as amended and under Article VI, Section 1 (r) of the Constitution and Bylaws of the Shoshone-Bannock Tribes of the Fort Hall Indian Reservation of Idaho.

Dated this 4th day of June, 2010. Signature

Shoshone-Bannock Tribes Waste Management Act Soil Cleanup Standards for Contaminated Properties - Revision 1 - April 15, 2010


Table of Contents


Introduction
1.1 Purpose and Authority
1 1.2 Framework for the Cleanup Standards
1.3 Chemicals Not Listed in the Lookup Tables
1.4 Limitations

2 Using the Lookup Tables
2.1 Organization of the Lookup Tables
2.2 Using the Lookup Tables
2.3 Substituting Laboratory Reporting Limits for Cleanup Standards
2.4 Naturally Occurring Concentrations for Cleanup Standards
2.5 Cumulative Risks at Sites with Multiple Contaminants
2.6 Evaluation of Petroleum Contamination
2.7 TSCA Cleanup Levels for PCBs

3 Petitions for Alternate Standards or Waiver
3.1 Petition to Use Commercial/Industrial Cleanup Standards
3.2 Petition for Waiver from Cleanup Standards Due to Technical Impracticability
3.3 Judicial Review

4 Site-Specific Standards
4.1 Site Considerations
4.2 Type 1 Site-Specific Risk Assessments
4.3 Type 2 Site-Specific Risk Assessments
4.4 Developing a Conceptual Site Model
4.5 Guidance on Environmental Risk Assessments

5 References
Lookup Tables
Table A: Shoshone-Bannock Tribes' EWMP Soil Cleanup Standards T-1
Table B: Shoshone-Bannock Tribes' EWMP Soil Cleanup Standards Indoor Air and Soil Gas (Vapor Intrusion Concerns) T-4

Figures
FIGURE 1 Summary of Health and Environmental Concerns
Considered in Cleanup Standards F-1

FIGURE 2 Tribal Exposure Pathways Based on a Subsistence Lifestyle F-2

FIGURE 3 Tribal Risk Assessment with Three Components F-3

FIGURE 4 Tribal Risk Assessment with Four Components F-4

FIGURE 5 Categories of Environmental Functions Contributing to Individual and Community Health F-5

Other Tables

TABLE 1 Traditional Lifeways — Typical Activities in the Activity Categories A-1

TABLE 2 Major Activity Categories A-2

TABLE 3 Example Exposure Considerations for Major Categories A-3

Introduction 1.1

Purpose and Authority

The Shoshone-Bannock Tribes ("Tribes") Soil Cleanup Standards ("Cleanup Standards") were developed pursuant to Section 201(B) of the Shoshone-Bannock Tribes Waste Management Act ("WMA"), which authorizes the Environmental Waste Management Program ("EWMP," or "the Program") to promulgate regulations necessary to carry out the purposes of the WMA. In WMA § 101, the Fort Hall Business Council states its policy to "preserve, protect, and enhance the environmental quality of the Tribal homeland, Fort Hall Reservation, for present and future generations," § 101(A), and to "restore and maintain environmental quality on the Reservation," § 101(D)(5). See also WMA §§ 103-104 (providing for the management and cleanup of wastes within the Fort Hall Reservation and all trust lands).

The Cleanup Standards also are promulgated pursuant to WMA § 605(D)(2), which authorizes the EWMP to promulgate applicable or relevant and appropriate requirements ("ARARs"), as defined under WMA § 105(C), for response actions at contaminated sites on the Reservation. The Cleanup Standards are intended to be ARARs and are intended to prevent threats to human health and the environment and to natural and cultural resources within the Reservation. See WMA § 211(D) (regulations to protect human health, natural and cultural resources, and the environment).

The Tribes' goal in promulgating the Cleanup Standards is to restore all land within the Reservation to its original state, that is, prior to the contamination that the standards are designed to address. The Reservation was set aside for the absolute and undisturbed use and occupation of the Tribes, as a home in perpetuity for the members of the Tribes, pursuant to the Treaty with the Eastern Band Shoshoni and Bannock of 1868, made at Fort Bridger, 15 Stat. 673, by the United States of America. The traditional and agricultural use of the land and natural resources of the Reservation is the lifeblood of the Shoshone-Bannock Tribes, and must be preserved. In addition, the Tribes' deeply rooted traditional and cultural connection with the land is integrally related to the well-being of Tribal members and overall Tribal morale. The WMA recognizes this integral connection, and consequently states that "[t]raditional, religious and cultural uses dependent upon Reservation lands and water must be protected to maintain the way of life and traditional activities of the Tribes," WMA § 101(B)(6). The Tribes recognize, however, that there are situations where the Tribes' goal of restoring all Reservation land to its original state may not be feasible, and the Cleanup Standards provide alternatives for these situations, as discussed further in Chapter 3 below.

Terms used in these regulations shall have the meanings provided in the WMA, unless specifically defined otherwise.


1.2 Framework for the Cleanup Standards

The Cleanup Standards are listed in the "Lookup Tables" attached to this document. They specify soil concentrations for over 100 hazardous chemicals, in amounts that the EWMP considers below the threshold of concern for human health and the environment.

The Cleanup Standards are based on the San Francisco Bay Area Regional Water Quality Control Board Environmental Screening Levels ("ESLs"),1 which consider adverse environmental effects of contamination in addition to direct human health impacts. The ESLs, revised in May 2008, are in turn based on the January 2005 California Human Health Screening Levels ("CHHSLs"),2 which were developed under the California Land Environmental Restoration and Reuse Act of 2002. The CHHSLs present concentrations of 54 hazardous chemicals in soil and soil gas3 that the California Environmental Protection Agency ("Cal/EPA") considers below the threshold of risk to human health, that is, an excess lifetime cancer risk of one-in-a-million (10-6) and a hazard quotient of 1.0 or less for non-cancer health effects.4

The CHHSLs were designed to protect human health from direct and indirect exposure to contaminated soil through ingestion and dermal absorption, the inhalation of vapors and dust outdoors, and the inhalation of subsurface vapors that have been emitted to the interiors of buildings. They were developed using the standard exposure assumptions and chemical toxicity values embodied in the USEPA Region 9 Preliminary Remediation Goals ("PRGs").5 The ESLs, however, use Cal/EPA toxicity and skin absorption factors for specific contaminants, when available, rather than using those factors published by USEPA. Because the ESLs incorporate the CHHSLs, the assessments' respective screening levels for soil and soil gas are essentially identical, except that the ESLs have used a more conservative hazard quotient of 0.2 to calculate screening levels for non-carcinogens. The ESLs assume that up to five chemicals with similar non-cancer health effects may be present at a given site, and so


http://www.swrcb.ca.gov/rwqcb2/water_issues/available_documents/ESL_May_2008.pdf. 2 http://www.calepa.ca.gov/Brownfields/documents/2005/CHHSLs Guide.pdf. 3 Soil gas refers to gaseous elements and compounds — such as air, water vapor, and pollutants — that are found in the small spaces between particles of soil or rock, and which may be carried by air leakage into a building, or otherwise moved through or from the substrate depending on changes in pressure. The CHHSLs do not include screening levels for direct-exposure volatile organic compounds ("VOCs") — as they present direct-exposure screening levels in regards to contaminated soil for semi-volatile and non-volatile compounds only —but they do include VOC-specific soil gas screening levels for potential vapor intrusion concerns. 4 Exposure criteria for contaminated media vary with the characteristics of the exposed population and on the frequency and duration of its exposure. Estimates of non-cancer risks thus assume there is a level of exposure below which it is unlikely for an individual to experience adverse health effects. One common method of evaluating non-cancer risks is to generate a hazard quotient: the ratio of exposure to the relevant toxicity value for each contaminant, which value is derived from experimental or epidemiological data, and is expressed as a daily reference dose ("RfD"). 5 http://vvww.epa.goviregion09/superfund/prg/. The PRGs are now historic, as they "have been harmonized with similar risk-based screening levels ["RSLs"] used by Regions 3 and 6." As of April 2009, the PRGs have been supplanted by RSL Tables. divide the initial screening level, based on a hazard quotient of 1.0, by a factor of five, thereby taking potential cumulative health risks into account.

Moreover, the ESLs present screening levels for more than 100 commonly detected contaminants6 and account for a breadth of ecological concerns not reached by the CHHSLs: the leaching of contaminants into groundwater; toxicity to flora and to terrestrial and aquatic receptors (through the contamination of soil and/or groundwater discharge to surface water); sullied drinking water; and the gross contamination of groundwater and soil (nuisance odors, e.g., and general resource degradation). As compared to the PRGs, the ESLs have for instance added soil and groundwater screening levels for Total Petroleum Hydrocarbons (TPH) and a more rigorous leaching model vis-à-vis groundwater quality.

The ESLs contain four sets of lookup tables, differentiated to account for specific site characteristics: shallow soils/potential drinking water resource threatened (Table A); shallow soils/potential drinking water resource not threatened (Table B); deep soils/potential drinking water resource threatened (Table C); and, deep soils/potential drinking water resource not threatened.7 In addition, each of the tables provides separate soil screening levels for residential and commercial/industrial land use. Residential use assumes sites will be used for residences, hospitals, daycare centers, and other sensitive purposes. Commercial/industrial use assumes that only working-age adults will be present at the site on a regular basis.

Chapter 6 of the ESLs explores the technical bases and limitations used to calculate screening levels for the two land use scenarios: duration of exposure to carcinogenic and non-carcinogenic contaminants, and the age-adjustment of exposure parameters. In summary, a residential receptor is assumed to be an adult or child who occupies a dwelling on the site 24 hours per day, 350 days per year, for thirty years. Exposure to soil is expected to occur during home maintenance activities, yard work and landscaping, and outdoor play. The duration of exposure to carcinogens is averaged over the receptor's lifetime because cancer may develop even after the exposure has ceased. The exposure parameters are age-adjusted for children (1-6 years old) and adults (7-31 years old), given the physiological and behavioral differences between them. Non-carcinogenic contaminants on residential sites are evaluated based solely on childhood exposures: higher contaminant intake is paired with lower relative body weight. See generally

ESLs at 6-2 to 6-6. In contrast, ESLs for non-residential uses are based solely on exposures to adults, but given "the wide range of activities and exposure levels a non-residential receptor may be exposed to during various work-related activities, it is important to ensure that the default exposure parameters are representative of site-specific conditions." See generally


6 These screening levels include direct exposure to VOCs from contaminated soil. Shallow soils refers to a depth of three meters, where a potential exists for regular direct exposure of residents and/or office workers (and also of terrestrial flora and fauna), and deep soils refers to depths where only periodic exposure during construction and utility maintenance work is considered likely. The potential for deeper soils to be brought to the surface in the future would be evaluated on a site-by-site basis. Consequently, the ESLs for relatively non-mobile chemicals are generally less stringent for deep soils than the corresponding ESLs for shallow soils. In contrast, for chemicals that are easily leached from soil or potentially volatized to the air, groundwater and indoor-air protection concerns usually drive selection of the final ESL regardless of the depth of the contaminated soil, and the corresponding shallow and deep soil ESLs are identical.

ESLs at 6-6 to 6-7.
Chapters 4-5 and 7-9 of the ESLs explain how the values found in the lookup tables and additional screening levels were developed. Certain of these values reflect the results of general studies of national application, and others reflect algorithms and models calculated through site-specific variables. These approaches are described as conservative and protective. See ESLs at 1-10 ("The ESLs are intended to be conservative for use at the vast majority of contaminated sites in developed areas."); see also ESLs at 2-3 ("The lowest of the individual screening levels for each concern was selected for inclusion in the summary ESL tables . .").8 The ESLs may thus be used to screen sites where a release of hazardous chemicals has occurred for long-term, chronic threats. Data collected at a site is compared to the appropriate set of screening levels and the need for additional action quickly determined. Under most circumstances, the presence of contaminants in soil, soil gas, or groundwater in concentrations below the corresponding ESL can be assumed not to pose a significant health risk to people who may live (residential levels) or work (commercial/industrial levels) at the site, or to raise the ecological concerns described above.9 The presence of a chemical at concentrations in excess of an ESL suggests that further evaluation is warranted.


The EWMP based the Shoshone-Bannock Tribes Cleanup Standards on the ESLs because it determined that those numeric, scientifically determined benchmarks would be protective of bo . th the public health and the environment on the Reservation10 The EWMP believes that setting uniform cleanup standards, with provisions for waiver or alternative standards when appropriate, as opposed to using a tiered approach (see footnote 10) in all instances, is the best way to protect the Tribes' health, resources, and environment, and their traditional and cultural beliefs and values. Moreover, a uniform cleanup standard eliminates or reduces the time and expense otherwise required for owners and operators to prepare detailed environmental risk assessments."

Additional conservative assumptions in the ESLs are found, for example, in the total rainfall said to infiltrate the surface and reach groundwater and in that the biodegradation part of this process is admittedly overlooked. See ESLs 1-4, 6-14. At the same time, leaching-based screening levels were generated only for chemicals considered to be significantly soluble and mobile in groundwater under normal, ambient conditions, thereby excluding physical-chemical conditions that may promote the enhanced leaching of metals and other chemicals from soils or waste piles (e.g., mining-related wastes). 9 This is Tier 1 of the so-called Tiered Approach. Under Tier 2, selected components of the models used to develop the Tier 1 ESLs are modified with respect to site-specific data or considerations (e.g., assumed depth to contaminated groundwater), thus resulting in a revised screening level to be utilized as in Tier 1. Under Tier 3, alternative models and modeling assumptions are utilized to develop site-specific screening levels or final cleanup levels or to quantitatively evaluate the actual risk posed to human and/or ecological receptors by the contaminated media. See generally ESLs 1-1 — 1-2. 1° The research, methodologies, and calculations that undergird the San Francisco Soil Screening Levels, the Indoor Air and Soil Gas Screening Levels, and the Soil and Groundwater Screening Levels for TPH (Total Petroleum Hydrocarbons) are fully described in Chapters 6, 7, and 8, respectively, of the ESL document. Additionally, the many studies, articles, and reference works upon which the ESLs are based are listed in Chapter 1.0 of that document. A list of resources specific to these Cleanup Standards is found in Chapter 5 of this document. `/ ESLs are designed to eliminate the need for risk assessments wherever possible, and so are well-suited for use as cleanup standards. See ESL Document at 1-1, 1-10.


There are two sets of Cleanup Standards, one for the Unrestricted Use of the site in question and a second set for its Commercial/Industrial Use. The EWMP requires compliance in the first instance with the Unrestricted Use standards, to further the Tribes' goal of having land within the Reservation restored to the greatest extent achievable and to ensure that the Tribes' resources may be used for traditional and cultural purposes into the future, and not lost to contamination from commercial and industrial development. At the same time, the Tribes recognize that there are situations when commercial or industrial use of a site may be appropriate; in these instances, a waiver may be sought pursuant to § 3.1 for the application of the Commercial/Industrial Use standards.

Two Lookup Tables are associated with each set of Cleanup Standards. Table A presents Cleanup Standards that address direct exposure to contaminated soil through inhalation, ingestion, and dermal absorption. Table B presents indoor air and soil gas Cleanup Standards that address vapor intrusion concerns.

Soil, soil gas, and indoor air data collected at a site should be directly compared to the Unrestricted Use Cleanup Standard for each chemical and exposure pathway of concern. Under most circumstances, the presence of a chemical in soil, soil gas, or indoor air at concentrations below the relevant Cleanup Standard will be assumed not to pose a statistically significant short-or long-term health risk to adults or children who may live or work at the site, or who may otherwise interact with the site, and also not to pose a statistically significant short- or long-term adverse impact on the environment. There may be instances, however, where the Cleanup Standards are inadequate to protect human health and the environment or are otherwise inappropriate due to site-specific environmental concerns, as described in § 1.4 and 4.1. In those instances, further evaluation may be advisable and may, for example, include additional sampling at the site, consideration of ambient levels in the environment, and, depending on site information, perfoimance of a site-specific risk assessment as provided in Chapter 4. Where it is technically impracticable to meet the Cleanup Standards, a waiver from those standards may be granted, pursuant to § 3.2.

1.3 Chemicals Not Listed in the Lookup Tables

The Lookup Tables list over one hundred chemicals, many of which are commonly found at sites where releases of hazardous wastes have occurred. The EWMP plans to incorporate Cleanup Standards for additional chemicals that may similarly pose a risk to human health or the environment as they become available. The Cleanup Standards also will be updated as necessary to incorporate new exposure assumptions and chemical toxicity values for already-referenced chemicals. In addition, it is a requirement of these Cleanup Standards that soils that exhibit the characteristics of ignitability or reactivity, as those terms are defined under RCRA and federal regulations implementing RCRA, must be treated to eliminate those characteristics, or else be removed from the site. [Alternatively, the soils must be managed in such a way as to protect them from any material or conditions that cause them to ignite or react.] Any revisions to the Lookup Tables will be developed pursuant to the rulemaking procedures prescribed in WMA § 901.


1.4 Limitations

The EWMP recognizes that the Cleanup Standards may not be adequate to address every environmental condition that might be present at a contaminated site. Site-specific conditions that have the potential to make the Cleanup Standards either insufficient or too stringent may include, but are not limited to:

The presence of inorganic chemicals (e.g., metals) which are potentially mobile in leachate due to soil or groundwater conditions different from those assumed in development of the Lookup Tables (e.g., low pH in groundwater at mine sites);
• The existence of endangered or protected species that are impacted by the site;
• The presence of more than three known or suspected carcinogens or more than five identified chemicals with similar non-carcinogenic health effects; The presence of rivers, streams, etc. which establish a potential for erosion and the further concentration of contaminants in aquatic habitats; The presence of fruits, vegetables, and other plant life that are likely to be ingested by children and adults, including for traditional and cultural purposes; The presence of metals that naturally occur in the soil, and therefore require comparison to local background levels, see § 2.4, as the EWMP does not require cleanup of soil to below background levels;
• The presence of a naturally occurring substance in its unaltered form, or which is altered solely through naturally occurring processes or phenomena from a location where it is naturally found, see WMA § 605(B)(1), as the EWMP does not require the cleanup of these sorts of substances; and
• The presence of chemicals that are known to be biodegradable in the environment, and that therefore render the Cleanup Standards too stringent.12 Resources for identifying and evaluating these and other site-specific environmental concerns are provided in Chapter 4. 12

For example, Cleanup Standards for Total Petroleum Hydrocarbons (TPH) and many non-carcinogenic, petroleum-related compounds (e.g., xylenes) are driven by the protection of groundwater quality. If long-term monitoring demonstrates that actual impacts to groundwater are insignificant, then less stringent standards may be warranted.

2 Using the Lookup Tables

2.1 Organization of the Lookup Tables
Figure 1 summarizes the range of health and environmental concerns addressed by the Cleanup Standards, which are presented in the Lookup Tables that immediately follow Chapter 5 of this document.
As noted in § 1.2, there are two sets of Lookup Tables: Table A presents the Tribes' Soil Cleanup Standards, and Table B presents the Tribes' Indoor Air Quality and Soil Gas Cleanup Standards. Within each table, separate Cleanup Standards are presented for Unrestricted Land Use and Commercial/Industrial Land Use. A summary of models and exposure assumptions used for each land use can be found in the ESL Document referenced in Chapter 1. Also, as discussed in Chapter 1, the Shoshone-Bannock Tribes have a goal of restoring all land within the Reservation to unrestricted use, and thus the Cleanup Standards for Unrestricted Use are the default standards for all cleanup on the Reservation. These standards incorporate conservative assumptions regarding the long-term, frequent exposure of children and adults to contaminated soils, as well as possible ecological effects.

In contrast, Commercial/Industrial Use standards assume that only working age adults will be present at the site on a regular basis. Exposure assumptions incorporated into these Cleanup Standards are less conservative than assumptions used in the unrestricted land-use scenario. In some circumstances, described further in § 3.1, it may be appropriate to apply the Commercial/Industrial Use standards rather than the Unrestricted Use standards. Before applying the Commercial/Industrial Use standards, however, approval must be obtained from the EWMP, with the concurrence of the Land Use Planning Commission (LUPC), pursuant to § 3.1.

Unrestricted Use and Commercial/Industrial Use Soil Cleanup Standards are applicable to all depths of soils. Soils at the ground surface present immediate exposure concerns, while deeper soils could be brought to the ground surface at some time in the future, with subsequent potential exposure by human receptors. For example, exposure of workers to deep soils may occur during construction and utility maintenance work. In addition, deeper soils could have impacts on groundwater and present other ecological concerns.

The Cleanup Standards assume that all groundwater beneath a given site is a potential source of drinking water and that all shallow groundwater will ultimately discharge to a body of surface water and potentially impact aquatic organisms. Groundwater on the Reservation is shallow, and the Cleanup Standards were therefore developed to be protective of both drinking water resources and aquatic habitats. In addition, factors that may render groundwater unsuitable for drinking water purposes are not present on the Reservation.13


13 Such factors could include, for example, total dissolved solids in groundwater greater than or equal to 3,000 mg/L, or water-bearing units insufficiently permeable to produce an average, sustained yield of 200 gallons of water per day.


The Cleanup Standards account for chemicals that are highly mobile in the subsurface and easily leached from contaminated soil. For chemicals that are especially toxic to aquatic life (e.g., several long-chain hydrocarbons, pesticides and heavy metals), Cleanup Standards may be driven by surface water/aquatic habitat protection concerns. The standards also consider gross contamination issues such as the presence of free product and aesthetic or odor problems.

2.2 Using the Lookup Tables
A step-by-step approach for using the Lookup Tables follows:
Step 1. Check for Cleanup Standards Applicability and Updates
The owner or operator should check with the EWMP to determine whether the Cleanup Standards may be applied to the subject site and to ensure that the most current standards are used.
Step 2. Collect Data
Once the owner or operator is assured that the Cleanup Standards apply to a site, a thorough site investigation shall be conducted, in the course of which all chemicals of potential concern shall be identified. The scope and type of the site investigation will vary depending on the history of the site and the nature of the actual or suspected chemical release. Sampling objectives should be defined and agreed upon with the EWMP prior to field activities. For example, the objective may be to determine whether a release has occurred, to identify hot spots that may require an expedited removal action, to assemble sufficient data to determine whether site remediation is necessary, or to evaluate whether site conditions would be consistent with anticipated or desired land uses.
Step 3. Determine the Future Land Use
In general, as discussed in Chapter 1 above, the Cleanup Standards for Unrestricted Use will be applied when remediating contaminated sites. If, however, the owner or operator, in consultation with the EWMP, believes that the property would meet the waiver standards provided in § 3.1, and such a waiver is applied for and granted, the Cleanup Standards for Commercial/Industrial Use will be applied when remediating the particular site.
Step 4. Determine Exposure Pathway(s) and Any Need for Substitution of the Cleanup Standards
Once the future use of the site is determined, the owner or operator shall select the appropriate Lookup Table based on the designated land use and anticipated exposure pathways. Where more than one Cleanup Standard applies, the most stringent standard shall be selected. Conditions that may result in adjustments to or replacement of particular cleanup standards are discussed in §§ 2.3 through 2.5.
Step 5. Compare Site Data To Cleanup Standards
The owner or operator shall compare the collected site data to the relevant Cleanup Standards or substituted values to identify areas where concentrations of contaminants are higher than allowed and thus raise potential concerns for human health and the environment. Soil data should be reported on a dry-weight basis. For sites where sample data are limited, the maximum-detected concentrations of chemicals of concern should be compared to the Cleanup Standards. For commercial/industrial areas, soil data may be averaged throughout the known or anticipated outdoor work areas, if needed.
2.3 Substituting Laboratory Reporting Limits for Cleanup Standards
The EWMP shall review and approve the analytical methods an owner or operator proposes to use to identify and quantify the chemicals found in soil samples so as to ensure sufficient sensitivity to low concentrations of chemicals of potential concern and the attainment of detection limits at or below the Cleanup Standards. The EWMP may allow the use of a laboratory method reporting limit in place of a Cleanup Standard for a particular substance where the Cleanup Standard is less than the equivalent laboratory method reporting limit. An example is the soil direct-exposure Cleanup Standard for dioxin for Unrestricted Use.
2.4 Naturally Occuring Concentrations for Cleanup Standards
Naturally occurring background concentrations of arsenic, beryllium, cadmium, chromium, and other metals within Reservation soils may exceed their respective Cleanup Standards. The EWMP does not require soil cleanup below background levels. The background concentration of any substance of concern for a particular site should be determined by analyzing samples from the uncontaminated areas of that site using guidance published by USEPA. Background data for nearby sites may be substituted for uncontaminated site data, but only if the data are obtained from soil of the same lithology as that found on site. Additionally, pursuant to WMA § 605(B)(1), the EWMP does not require cleanup of a naturally occurring substance in its unaltered form, or which is altered solely through naturally occurring processes or phenomena from a location where it is naturally found. See § 1.4.


2.5 Cumulative Risks at Sites w h Multiple Contaminants
The human risks posed by exposure to multiple chemicals with similar health effects are considered to be cumulative. For example, the total excess lifetime risk of cancer posed by the presence of several carcinogenic chemicals in all exposure media is the sum of the risk posed by each individual chemical. The same is true for chemicals that cause non-carcinogenic health effects. Because of conservative exposure assumptions built into the Cleanup Standards and target risk factors in direct exposure models, the Cleanup Standards are adequate for use at sites where no more than three carcinogenic chemicals or five chemicals with similar non-carcinogenic health effects are present. When more than these numbers of contaminants are present at a site, a stepwise approach for cleanup is suggested (see PRG Document (USEPA 2004)):


Step 1: Identify potential chemicals of concern.

Step 2: Record Cleanup Standards for each chemical.

Step 3: Calculate cumulative cancer risk estimates by taking the assumed exposure point concentration ("Cone") for each chemical (maximum or approved 95% UCL) and divide that value by the respective Cleanup Standard ("CS") of the chemical in question. Multiply the ensuing ratio by 10-6 (that is, an excess lifetime cancer risk of one-in-a-million) to calculate the estimated cancer risk for that specific chemical for a reasonable maximum exposure. For multiple chemicals, simply add the estimated cancer risks for the individual chemicals or sum the ensuing ratios for each of the individual chemicals and multiply this total by 10-6.

Risk = [ [Concx/CSx + [Concy/CSy] + [Conc/CSz] + ......] x 10-6

Step 4: Calculate cumulative non-cancer hazard estimates by taking the assumed exposure point concentration for each chemical (maximum or approved 95% UCL) and divide that value by the respective Cleanup Standard of the chemical in question. This generates an individual hazard quotient for that chemical. It is then possible to calculate a cumulative hazard index by adding the individual hazard quotients. A hazard index of one or less is generally considered below the threshold of risk to human health. A ratio that is greater than one suggests that further evaluation is necessary.

Hazard Index = [ [Concx/CS]+ [Conc./CSy] + Conc=/CS=] +... ]1

Note that carcinogens may have Cleanup Standards for both cancer and non-cancer effects.

2.6 Evaluation of Petroleum Contamination

The potential contamination of soil, water, and air by petroleum mixtures is to be evaluated in terms of the presence of both Total Petroleum Hydrocarbons ("T P H") and the target indicator chemicals for a given petroleum mixture. Cleanup Standards for both the petroleum mixtures and the individual target indicator chemicals are found on the Lookup Tables. Indicator chemicals typically recommended for petroleum mixtures include (after Cal/EPA 1996a and 1996b):

A. Aromatic Compounds (Indicating, Primarily, Gasolines and Middle Distillates) • Benzene • Ethyibenzene • Toluene • Xylene

B. Fuel Additives (Indicating, Primarily, Gasolines • MtBE • other oxygenates

C. Polycyclic Aromatic Compounds (Indicating, PMiddle Distillates and Fuels) • Acena phthene • Acenaphthylene • Anthracene • Benzo(a)anthracene • Benzo(b)fluoranthene • Benzo(g,h,i)perylene • Benzo(a)pyrene • Benzo(k)fluoranthene • Chrysene • Dibenz(a,h)anthracene • Fluoranthene • Fluorene • Indeno(1,2,3-c,d)pyrene • Methylnaphthalene (1- and 2-) • Naphthalene • Phenanthrene • Pyrene

The middle distillates petroleum mixture includes diesel fuel kerosene, Stoddard Solvent, home heating fuel, jet fuel, and the like. Residual fuels include heavy petroleum products such as bunker fuel (No. 6 fuel oil), lubricating oils, grease, waste oils, and asphalts. Soil and groundwater contaminated by releases of waste oil may also require testing for heavy metals and chemicals such as chlorinated solvents and polychlorinated biphenyls ("PCBs"). (The Lookup Tables present screening levels for these chemicals.) Trimethylbenzenes, butylbenzenes, methylnaphthalenes, and other common constituents of petroleum products (especially gasolines) are sometimes reported separately in analyses of contaminated soil and groundwater. In general, however, these chemicals should be collectively evaluated under the pertinent TPH and do not need to be evaluated individually.


2.7 TSCA Cleanup Levels


PCBs The treatment, storage, and disposal of PCBs are regulated under the federal Toxics Substance Control Act and 40 C.F.R. Part 761, which are administered by EPA. If PCBs are found at a site, the Act and regulations must be consulted to determine the applicability of these laws and to ensure that the appropriate notifications are provided to and approvals obtained from EPA. See generally USEPA, Guidance on Remedial Actions for Superfund Sites with PCB Contamination, (1990), available at http://www.epa.gov/superfund/policy/remedy/pdfs/ 540g-90007-s.pdf.14

14 See http://vv-ww.epa.gov/epawaste/hazard/tsd/pcbs/index.htm for more information on PCB regulations and guidance. For information specific to USEPA Region 10, see http://yosemite.epa .gov/R10/0WCM.NSF/webpage/Polychlorinated+Biphenyls+(PCBs)+Homepage?OpenDocument,

3 Petitions to Alternate Standards or Waiver

3.1 Petition to Use Commercial/Industrial Cleanup Standards

(a) Pursuant to WMA § 605(D)(2), an owner or operator of a facility at a site subject to cleanup may petition the EWMP for permission to apply the Commercial/Industrial Use Cleanup Standards to the site instead of the Unrestricted Use Standards. The procedures set forth in WMA § 701(A)

(B) shall apply to such petitions, except that a grant of the petition shall be based on the factors set forth in subsection (b) of this section and the required contents of the application shall be modified accordingly from those set forth in WMA § 701(A). (b) A grant of the petition shall be based on a demonstration that:

(1) in light of land-use planning documents, zoning laws, leases, or other similar evidence, the site in question will be used only for commercial or industrial purposes for the foreseeable future;

(2) there are no traditional or cultural resources at or in close proximity to the site that may be adversely affected by application of the Commercial/Industrial Use Standards instead of the Unrestricted Use Standards; and

(3) the release of any waste, pollutant or contaminant, as those terms are defined in WMA § 105, will not migrate beyond the boundaries of the site, for example through leaching into groundwater, being suspended in dust, or by any other means.

(c) If the petition to use Commercial/Industrial Cleanup Standards is granted, it must provide for creating (if necessary) and maintaining restrictions on the use of the site to ensure that it is used in the foreseeable future only for commercial/industrial purposes, and not for residential or other unrestricted uses.

(d) The EWMP shall obtain the concurrence of the Land Use Planning Commission ("LUPC") before making a determination that the requirements of subsections (b)(1) and (c) are satisfied.

(e) The EWMP may provide, by regulation, for processing fees to be included with the petition.


3.2 Petition for Waiver from Cleanup Standards Due to Technical Impracticability

(a) Pursuant to WMA § 605(D)(2), an owner or operator of a facility at a site subject to cleanup may petition the EWMP for a waiver to apply one or more cleanup standards other than the Unrestricted Use or Commercial/Industrial Use Cleanup Standards due to technical impracticability. The procedures set forth in WMA § 701(A)-(B) shall apply to such petitions, except that a grant of the petition shall be based on the factors set forth in subsection (b) of this section and the required contents of the application shall be modified accordingly from those set forth in WMA § 701(A). Petitions for waiver of Cleanup Standards at only a portion of the site in question, and that propose alternative standards that are as close as practicable to the Cleanup Standards, will be favored.

(b) The EWMP will grant a petition for a waiver under this section if it finds that:

(1) Appropriate remediation technology has been attempted for an amount of time sufficient to evaluate whether it can reliably achieve the Cleanup Standards at issue. At a minimum, a claim of technical impracticability must be supported by two consecutive years of quarterly site-monitoring data showing that the degree of contamination is leveling or has leveled off and no other remediation method could appropriately achieve a reduction in contamination;

(2) There is no reasonable relationship between the economic and social costs that would be incurred and the benefits that would be obtained by continuing to attempt to achieve the Cleanup Standards in question, once the burden in paragraph

(1) of this subsection has been met; and The proposed alternative standards are technically achievable, are protective of human health and the environment, and do not violate applicable federal standards. In no case may the EWMP approve alternative cleanup standards that violate applicable federal requirements unless permission has been obtained from the relevant federal agencies to deviate from those requirements.

(c) Failure to achieve the Cleanup Standards because of inadequate system design or operation or unsuitability of the technology for site conditions shall not be considered sufficient justification for a waiver under this section.

(d) The role of cost in a determination of technical infeasibility is subordinate to the goal of ensuring protection of human health and the environment, and in some cases high costs may be appropriate.

(e) The grant of a technical impracticability waiver under this section is intended to be as identical as possible to a grant of a technical impracticability waiver under § 12I(d)(4)(C) of CERCLA, and EPA guidance, policies, and precedents interpreting that provision of CERCLA shall guide implementation of this section.

(f) The EWMP may provide, by regulation, for processing fees to be submitted together with the petition for a waiver.

3.3 Judicial Review

Any aggrieved person seeking to challenge a final decision of the EWMP regarding a petition for a waiver pursuant to § 3.1 or 3.2, above, is entitled to judicial review in Tribal Court pursuant to WMA § 902.

4 Site-Specific Standards


The EWMP will promulgate procedures for developing site-specific standards as part of the Shoshone-Bannock Waste Response Plan ("WRP") promulgated pursuant to WMA § 603. The WRP, and thus the procedures for conducting site-specific risk assessments, will be subject to the rulemaking provisions of WMA § 901. This chapter describes the types of site conditions that may lead the EWMP to require or to approve an owner's or an operator's request for preparation of site-specific standards. It also describes two types of site-specific environmental risk assessments that may be conducted, depending on the degree of site evaluation required, and discusses elements of the conceptual site model to be used in conducting site-specific risk assessments.

Notwithstanding the preceding paragraph, it is a requirement of these Cleanup Standards that soils that exhibit the characteristics of ignitability or reactivity, as those terms are defined under RCRA and federal regulations implementing RCRA, must be treated to eliminate those characteristics, or else the soils must be removed from the site. [Alternatively, the soils must be managed in such a way as to protect them from any material or conditions that cause them to ignite or react.]

4.1 Site Considerations

The EWMP may determine, either on its own initiative or at the request of the owner or operator, that site conditions are such as to render inappropriate the use of some or all of the Cleanup Standards for some or all portions of the site, and to require preparation of alternative, site-specific standards in those instances.

Examples of site conditions that may warrant site-specific standards include those listed in § 1.4. Others might include the following:

Sites where impacts pose increased threats to sensitive ecological habitats, such as sites adjacent to wetlands or streams, or areas where cultural resources are present;

Sites where physical conditions substantially differ from those assumed in the development of the Cleanup Standards (such sites may include, for example, mine sites or landfills with high or low pH); and

Sites with contaminants for which Cleanup Standards have not been developed.

Depending on the extent of modifications needed to the Cleanup Standards, a Type 1 or a Type 2 site-specific risk assessment may be selected, as described further below. Under either type of assessment, however, the EWMP shall ensure that human health, resources, and the environment will be adequately protected, and will minimize deviations from the Cleanup Standards to the extent possible while taking into account specific site conditions. Site-specific standards will be designed so as to meet a cancer risk level of 10-6 and a non-cancer hazard quotient of 0.2, the same as the Cleanup Standards. As in the case of waivers from the Cleanup Standards under § 3.2, the EWMP shall not approve site-specific cleanup standards that violate applicable federal requirements unless permission has been obtained from the relevant federal agencies to deviate from those requirements.

4.2 Type 1 Site-Specific Risk Assessments

Under a Type 1 site-specific risk assessment, selected components of the assumptions on which the Cleanup Standards are based are modified to reflect site-specific data or considerations. For example, the indoor air exchange rate might be adjusted if it is shown to be more or less than assumed in the relevant Cleanup Standards, but the rest of the assumptions in the Cleanup Standards may be appropriate vis-à-vis the site. This situation would result in limited revisions to the Cleanup Standards, with the remaining standards continuing to be applicable.

This approach is based on the Tier 2 environmental risk assessments in the ESLs, and provides a relatively rapid and cost-effective option for preparing site-specific standards. Replacing only targeted components of the Cleanup Standards reduces the need to prepare and justify an independent, detailed risk assessment, which greatly reduces the time and cost incurred by both the regulated business and the EWMP.

4.3 Type 2 Site Specific Risk Assessments

Under a Type 2 site-specific risk assessment, alternative models and modeling assumptions would be used and fully justified to develop site-specific cleanup standards. Portions of the Cleanup Standards may still be retained, but significantly greater modifications would be required than under the Type 1 assessment. This approach is based on the Tier 3 environmental risk assessments in the ESLs.

4.4 Developing a Conceptual Site Model

If the EWMP determines, pursuant to Section 4.1, that site-specific standards are warranted, either in whole or in part, a conceptual site model ("CSM") will be required as part of the environmental risk assessment performed for the site. The CSM presents information about site conditions, likely contaminant source areas, exposure pathways, and potential receptors. A CSM summarizes information about site conditions in a schematic presentation in terms of:
1) primary sources (e.g., leaking tanks);
2) secondary sources (e.g., contaminated soil);
3) contaminant transport mechanisms (e.g., volatilization and intrusion into buildings);
4) contaminated exposure media (e.g., indoor air); and
5) potentially complete exposure pathways.

A CSM also can be used to provide a rationale for additional site investigation. The level of detail required in a conceptual site model will vary from site to site. The presentation and scope of the model should be discussed with the EWMP. The conceptual site model should be continually updated to reflect new information.

Additional information regarding the preparation of CSMs is provided in USEPA, Preliminary Remediation Goals (2004); the USEPA Guidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA, Interim Final (USEPA 1988); and SFBWQCB, Screening for Environmental Concerns at Site with Contaminated Soil and Water 2- 24 to 2-27 (2003).

A schematic of tribal exposure pathways is presented in Figure 2. As noted in § 1.1, the Tribes' and their members' well-being is integrally related to the environment, in a way not typically accounted for in most exposure evaluation models. In addition, typical exposure evaluation models reflect exposures received in urban and suburban settings and do not consider the extent of tribal environmental contact. Although contemporary resource uses may not be the same as traditional resource uses, the Tribes' goal is to restore the health of tribal individuals and community.

Figure 2 is based on the knowledge that, for Native Americans,

[t]he quality of the socio-cultural and eco-cultural landscapes is very important, as is the quality of individual natural resources or ecosystem integrity. . . . [I]ndividual and collective well being is derived from membership in a healthy community that has access to, and utilization of, ancestral lands and traditional resources. This wellness stems from and is enhanced by having the opportunity and ability to live within traditional community activities and values. . .

Therefore, if the link between a person and his/her environment is severed through the introduction of contamination or physical or administrative disruption, the person's health suffers, and the well being of the entire community is affected.

Harper, Barbara L., et al. Traditional Tribal Subsistence Exposure Scenario and Risk Assessment Guidance Manual 11-12 (2007). Moreover,
performing a tribally relevant risk assessment means more than simply performing an ecological risk assessment with culturally important species and/or using a human exposure scenario that includes exposures received during cultural activities. It means developing an exposure scenario that reflects the lifestyle [that] treaties (or their equivalent) were designed to protect.

Id. at 12. These tribal factors therefore should be considered in the CSM.

4.5 Guidance on Environmental Risk Assessments

Guidance on the preparation of site-specific baseline environmental risk assessments is provided in the following references:

Harper, Barbara L., et al. Traditional Tribal Subsistence Exposure Scenario and Risk Assessment Guidance Manual. (Aug. 2007.)

Johnson, P.C., et al. Assessing the Significance of Subsurface Contaminant Vapor Migration to Enclosed Spaces. (Dec. 1998.)

USEPA, 1997a. Exposure Factors Handbook. (Aug. 1997.)

USEPA, 1997b. Ecological Risk Assessment Guidance for Superfund: Process o Designing and Conducting Ecological Risk Assessments. (June 1997.)

Cal/EPA, 1996a. Supplemental Guidance For Human Health Multimedia Risk Assessments of Hazardous Waste Sites and Permitted Facilities. (Aug. 1996.)

Cal/EPA, 1996b. Guidance for Ecological Risk Assessments at Hazardous Waste Sites and Permitted Facilities. (July 1996.)

USEPA, 1996. Soil Screening Guidance: Technical Background Document. (May 1996.)

Cal/EPA 1994b. Preliminary Endangerment Assessment Guidance Manual. (Jan. 1994.)

Cal/EPA, 1994a. CalTOX: A Multimedia Total Exposure Model For Hazardous-Waste Sites. (Dec. 1993.)

USEPA, 1989a. Risk Assessment Guidance for Superfund. Volume I, Human Health Evaluation Manual (Part A). (Dec. 1989.)

USEPA, 1989b. Risk Assessment Guidance for Superfund. Volume H, Environmental Evaluation Manual. (Mar. 1989.)

Additionally, Figures 2 - 4 and Tables 1 – 3 present typical traditional activities and exposure considerations to be considered in developing a tribal risk assessment.

5 References

Cal/EPA, 1994a. CalTOX- A Multimedia Total Exposure Model for Hazardous Waste Sites. Environmental Protection Agency, Department of Toxics Substances Control. Version 1.5 and updates (Dec. 1993). http://www.dtsc.ca.gov/AssessingRisk/upload/techman1-2,pdf.

Cal/EPA, 1994b. Preliminary Endangerment Assessment Guidance Manual. California Environmental Protection Agency, Department of Toxics Substances Control (Jan. 1994).

Cal/EPA, 1996a. Supplemental Guidance for Human Health Multimedia Risk Assessments of Hazardous Waste Sites and Permitted Facilities. California Environmental Protection Agency, Department of Toxics Substances Control (Aug. 1996). http://www.dtsc.ca.gov/AssessingRisk/ Supplemental _Guidance.cfm.

Cal/EPA, 1996b. Guidance for Ecological Risk Assessments at Hazardous Waste Sites and Permitted Facilities (Parts A and R) California Environmental Protection Agency, Department of Toxics Substances Control (July 1996). http://www.dtsc.ca.gov/AssessingRisk/upload/overview.pdf and http://www.dtsc.ca.gov/AssessingRisklupload/scope.ix1f.

Cal/EPA, 1997. Selecting Inorganic Constituents as Chemicals of Potential Concern at Risk Assessments at Hazardous Waste Sites and Permitted Facilities, Final Policy California Environmental Protection Agency, Department of Toxics Substances Control. (Feb. 1997.) http://www.dtsc.ca.gov/AssessingRisk/upload/backgrnd.pdf.

Cal/EPA, 2002. Response Actions for Sites where Future Uses May Include Sensitive Uses. California Environmental Protection Agency, Department of Toxic Substances Control, Site Mitigation and Brownfields Reuse Program. Management Memo E0-02-002-MM. (July 2002.)

Cal/EPA, 2004b. Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air. California Environmental Protection Agency, Department of Toxics Substances Control. (Dec. 2004.)

http://www.dtsc.ca.gov/assessingrisk/upload/herdpol eval_subsurface vapor_ intrusion_interim_final.pdf.

CLRA, 2002. California Land Restoration and Reuse Act. California Health and Safety Code. Section 25401 et seq. and Section 57009 et seq. http://www.leginfo.ca.gov/calaw.html.

Harper, Barbara L., et al. Traditional Tribal Subsistence Exposure Scenario and Risk Assessment Guidance Manual. Report of Grant No. EPA-STAR-J1-R831046. (Aug. 2007.) http://www.hhs.

oregonstate.edulph/sites/default/files/xposure_Scenario_and Risk Guidance_Manual v2. pdf.

Johnson, P.C., et al. Assessing the Significance of Subsurface Contaminant Vapor Migration to Enclosed Spaces. American Petroleum Institute, Health and Environmental Sciences Department. API Publication No. 4674. (Dec. 1998.)

LBNL, 2002. Analysis of Background Distributions of Metals in the Soil at Lawrence Berkeley National Laboratory. University of California (Berkeley), Lawrence Berkeley Laboratory. (June 2002.)

MADEP, 1994. Background Documentation for the Development of the MCP Numerical Standards. Massachusetts Department of Environmental Protection, Bureau of Waste Site Cleanup and Office of Research and Standards. (April 1994.) http://www.mass.govidep/cleanup/bacdoc.pdf.

MADEP, 1995. Guidance For Disposal Site Risk Characterization. Massachusetts Department of Environmental Protection, Bureau of Waste Site Cleanup and Office of Research and Standards. (July 1995.) http://www/mass.gov/dep/cleanup/laws/rcl.pdf; http://www/mass.gov/dep/cleanup/Iaws/rc2.pdf; and http://w-ww/mass.gov/dep/cleanup/laws/re3.pdf.

MOEE, 1996. Rationale for the Development and Application of Generic Soil, Groundwater and Sediment Criteria for Use at Contaminated Sites in Ontario. Ontario Ministry of Environment and Energy, Standards Development Branch. (Dec. 1996.)

NOAA, 1999. Sediment Screening Reference Tables. National Oceanic and Atmospheric Organization, Coastal Protection and Restoration Division. (Sept. 1999.) http://response.restoration.noaa.gov/ cpr/sediment/squirt/squirt.html.

Rope, Susan K., et al. "Nutrient and Trace Elements in Soil and Desert Vegetation of Southern Idaho." Environmental Monitoring and Assessment Journal. (Jan. 1988.)

SFBRWQCB, 2003. Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater. California Regional Water Quality Control Board, San Francisco Bay Region. (July 2003.)

http://www.swrcb.ca.gov/rwcicb2/water issues/available_documents/ESL_May_ 2008.pdf.

USEPA, 1988. Superfund Exposure Assessment Manual. United States Environmental Protection Agency, Office of Emergency and Remedial Response. Publication EPA/540/1-88/001. (Apr. 1988.)

USEPA, 1989a. Risk Assessment Guidance for Superfund: Volume I, Human Health Evaluation Manual (Part A). United States Environmental Protection Agency, Office of Emergency and Remedial Response. Publication EPA/540/1-89/002. (Dec. 1989.) http://www.epa.gov/oswer/risk assessment/ragsa/pdf/rags-vol 1 -pta_complete.pdf.

USEPA, 1989b. Risk Assessment Guidance for Superfund: Volume II, Environmental Evaluation Manual. United States Environmental Protection Agency, Office of Emergency and Remedial Response. Publication EPA/540/1-89/001. (Mar. 1989.) http://www.epa.gov/oswer/ risk assessment/ecoup/.

USEPA, 1994. Synthetic Precipitation Leaching Procedure. United States Environmental Protection Agency, Office of Solid Waste. SW-846 Method 1312. (Sept. 1994.) lattp://www.epa. gov/osw/ hazard/testmethods/sw846/pdfs/1312.pdf.

USEPA, 1996. Soil Screening Guidance: Technical Background Document. United States Environmental Protection Agency, Office of Emergency and Remedial Response. Publication 9355.417A. (May 1996.)

USEPA, 1997a. Exposure Factors Handbook. United States Environmental Protection Agency, Office of Research and Development. Publication EPA/600/P-95/002Fa, Fb, and Fc. (Aug. 1997.) http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12464.

USEPA, 1997b. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments. United States Environmental Protection Agency, Environmental Response Team. EPA 540-R-97-006. (June 1997.)

USEPA, 1999. Estimating Risk From Contaminants Contained in Agricultural Fertilizers (Draft). United States Environmental Protection Agency, Office of Solid Waste. (Au 1999.) http:// www.epa.gov/osw/hazwaste/recycle/fertiliz/risk/report.pdf.

USEPA, 2002. Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites. United States Environmental Protection Agency, Office of Emergency and Remedial Response. OSWER 9285.6-10. (Dec. 2002.)

USEPA, 2003. User's Guide for the Johnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings. United States Environmental Protection Agency, Office of Emergency and Remedial Response. (Sept. 1997 and updated.) http://www.epa.gov/oswer/riskassessment/air model/j ohnson ettinger.htm.

USEPA, 2004. Preliminary Remediation Goals. United States Environmental Protection Agency, Region 9. (Oct. 2004.)

http://www.epa.gov/region09/superfund/prg/files/04prgtable.pdf.