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CITATION of Administrative Rules

The Iowa Administrative Code shall be cited as (agency identification number) IAC
(chapter, rule, subrule, lettered paragraph, or numbered subparagraph).

441 IAC 79 (Chapter)

441 IAC 79.1(249A) (Rule)

441 IAC 79.1(1) (Subrule)

441 IAC 79.1(1)"a" (Paragraph)

441 IAC 79.1(1)"a"(1) (Subparagraph)

The Iowa Administrative Bulletin shall be cited as IAB (volume), (number), (publication
date), (page number), (ARC number).

IAB Vol. XII, No. 23 (5/16/90) p. 2050, ARC 872A

These rules may have an impact on small businesses as provided in Iowa Code section 17A.31.
The rules are intended to implement Iowa Code Supplement chapter 455H.
The following chapter is proposed.
Adopt the following new chapter:

Where: C = Concentration of contaminant (soil: mg/kg, water: mg/l)
RF = Risk factor
For protection from cancer health risks:
RF = TR÷SF
Where: TR = Target cancer risk (unitless)
SF = Oral slope factor per (mg/kg)/day;
see paragraph "c" for source.
For protection from noncancer health risks:
RF = THQ _ RfD
Where: THQ = Target hazard quotient (unitless)
RfD = Oral reference dose ((mg/kg))/day;
see paragraph "c" for source.
AT = Averaging time (years); time over which exposure is
averaged and potential adverse effects may occur
Abs = Absorption factor (unitless); portion of exposed
contaminant absorbed by the body
ER_c = Exposure rate by a child (soil: mg/day, water: l/day)
EF_c = Exposure frequency by a child (days/year)
ED_c = Exposure duration by a child (years)
BW_c = Body weight of exposed child (kg)
ER_a = Exposure rate by an adult (soil: mg/day, water: l/day)
EF_a = Exposure frequency by an adult (days/year)
ED_a = Exposure duration by an adult (years)
BW_a = Body weight of exposed adult (kg)
CF = Conversion factor: 10^-6 kg/mg for soils;
1 (unitless) for water
b. Carcinogenic classification of chemicals. The potential carcinogenicity of chemicals will be based on the weight-of-evidence classification system utilized by the U.S. Environmental Protection Agency (EPA). Risk-based concentrations will be based on cancer health effects for chemicals that are classified as Group A or Group B. Risk-based concentrations will be based on noncancer health effects for chemicals that are classified as Group C, Group D or Group E. In the absence of such classification for a chemical, the Group D classification will be assumed.
c. Source of toxicity values. Source of information on toxicity factors (e.g., oral reference doses and oral slope factors) and carcinogenic classification for chemicals shall be in accordance with the following hierarchy. The most recent version of each shall be used.
(1) EPA's Integrated Risk Information System (IRIS).
(2) EPA's Health Effects Assessment Summary Tables (HEAST).
(3) Best available information, including consultation with toxicologists at EPA's National Center for Exposure Assessment in Cincinnati, Ohio.
137.5(4) Statewide standards for groundwater.
a. Protected groundwater source. Statewide standards for groundwater in a protected groundwater source will be the enforceable Maximum Contaminant Level (MCL) established by the EPA pursuant to the Safe Drinking Water Act, if one exists. If no enforceable MCL exists, the statewide standard for chemicals will be the lifetime health advisory level (HAL) as provided in the latest "Drinking Water Regulations and Health Advisories" by the EPA's Office of Water or equivalent. If no MCL or HAL exists, the statewide standard for a chemical will be calculated using Formula I and input variables for groundwater ingestion in accordance with the following subparagraphs.
(1) Input variables for calculating statewide standards for chemicals in groundwater from a protected groundwater source based on cancer risk are as follows:
TR = 5 _ 10^-6
SF = Chemical-specific (see paragraph 137.5(3)"c")
AT = 70 years
Abs = 1
ER_c = 1 l/day
EF_c = 0 days/year
ED_c = 6 years
BW_c = 15 kg
ER_a = 2 l/day
EF_a = 365 days/year
ED_a = 70 years
BW_a = 70 kg
CF = 1
(2) Input variables for calculating statewide standards for chemicals in groundwater from a protected groundwater source based on noncancer risk are as follows:
THQ_c = 0.02 (Group C chemicals);
THQ_D,E = 0.2 (Group D and E chemicals)
RfD = Chemical-specific (see paragraph 137.5(3)"c")
AT = 70 years
Abs = 1
ER_c = 1 l/day
EF_c = 0 days/year
ED_c = 6 years
BW_c = 15 kg
ER_a = 2 l/day
EF_a = 365 days/year
ED_a = 70 years
BW_a = 70 kg
CF = 1
b. Groundwater in a nonprotected groundwater source. The statewide standard for a Group A or B chemical, except arsenic, in groundwater in a nonprotected groundwater source will be 20 times the statewide standard for the chemical in a protected groundwater source or a risk-based concentration using Formula I with TR = 10^-4 and the exposure factors specified in subparagraph 137.5(4)"a"(1), whichever is larger. The statewide standard in a nonprotected groundwater source for arsenic will be 0.1 mg/l. The statewide standard for a Group C chemical in a nonprotected groundwater source will be 50 times the statewide standard for the chemical in a protected groundwater source. The statewide standard for a Group D or E chemical in a nonprotected groundwater source will be 5 times the statewide standard for the chemical in a protected groundwater source. However, in no case will the statewide standard for a Group C, D, or E chemical in a nonprotected groundwater source be less than a risk-based concentration using Formula I with a THQ = 1 and exposure factors as specified in subparagraph 137.5(4)"a"(2). The statewide standards for groundwater in a nonprotected groundwater source are based on groundwater ingestion only.
137.5(5) Statewide standards for soil. Statewide standards for chemicals in soil, except lead, will be calculated using Formula I based on incidental ingestion of soil and dust with input variables in accordance with the following paragraphs. The statewide standard for lead in soil shall be 400 mg/kg.
a. Input variables for calculating statewide standards for chemicals in soil based on cancer risk are as follows:
TR = 10^-6
SF = Chemical-specific (see paragraph 137.5(3)"c")
AT = 70 years
Abs = 1
ER_c = 200 mg/day
EF_c = 350 days/year
ED_c = 6 years
BW_c = 15 kg
ER_a = 100 mg/day
EF_a = 350 days/year
ED_a = 64 years
BW_a = 70 kg
CF = 10^-6 kg/mg
b. Input variables for calculating statewide standards for chemicals in soil based on noncancer risks are as follows:
THQ = 1
RfD = Chemical-specific (see paragraph 137.5(3)"c")
AT = 6 years
Abs = 1
ER_c = 200 mg/day
EF_c = 350 days/year
ED_c = 6 years
BW_c = 15 kg
ER_a = 100 mg/day
EF_a = 350 days/year
ED_a = 0 years
BW_a = 70 kg
CF = 10^-6 kg/mg
137.5(6) Statewide standards for surface water. Water quality standards pursuant to 567--Chapter 61 shall be considered statewide standards for surface water. If a promulgated water quality standard does not exist for a contaminant of concern, the department may establish an appropriate standard in a manner consistent with 567--Chapter 61.
137.5(7) Statewide standards for air. Ambient air quality standards pursuant to 567--Chapter 28 constitute statewide standards for air. Air emission sources must meet air quality emission standards as set forth in 567--Chapters 20 through 31 inclusively, as applicable. Any relevant air quality standard that is subsequently promulgated by statute or rule shall become a statewide standard for air upon the effective date of adoption by the state. In the absence of applicable, adopted standards, site-specific air standards must be met, in accordance with subrule 137.6(8), when air quality issues are addressed at a site.
137.5(8) Point of exposure for statewide standards. The point of exposure associated with the use of only statewide standards in the determination of compliance will be assumed to be anywhere and everywhere, except for surface water. The point of exposure associated with the use of statewide standards for surface water will be assumed to be the point of groundwater or other site runoff immediately before it discharges to the surface water body.
137.5(9) Practical quantification limits. In no case will the statewide standard be less than the practical quantification limit, as determined by the department.
137.5(10) Maintenance of statewide standards. The toxicity values and promulgated standards that are a basis for statewide standards are subject to periodic revision due to actions not governed under this rule. The department will maintain a guidance document that contains a current list of statewide standards that will be readily available to the public. Statewide standards for individual sites will be locked-in at the beginning of the site assessment process (rule 137.8(455H)). If a statewide standard does not exist for a chemical, it will be the department's responsibility to establish a statewide standard, pursuant to subrules 137.5(4) and 137.5(5), for groundwater and soil, and to add it to the comprehensive list of statewide standards in the guidance document maintained by the department.
567--137.6(455H) Site-specific standards.
137.6(1) Purpose. Site-specific standards may be used in lieu of statewide standards when the assumptions which form the basis of statewide standards can be modified without compromising protection of human health, safety or the environment. Statewide standards may be used in combination with site-specific standards to address different exposure pathways. Site-specific standards may be required to address exposure pathways which the department determines must be evaluated to be protective of human health, safety and the environment and for which statewide standards have not been established under rule 137.5(455H). Site-specific standards may involve development of target levels for contaminants of concern based on site-specific exposure assumptions for use in lieu of background or statewide standards. Site-specific standards may also include consideration of the actual or potential location where exposure to contaminants occurs or may occur, the likelihood of an exposure occurring, and the overall magnitude and extent of contamination. Site-specific standards may involve use of site-specific target levels for contaminants of concern alone or in conjunction with other site-specific criteria, such as the location where the standard is applied.
137.6(2) General provisions.
a. This rule establishes a minimum protocol that must be met at all enrolled sites which have not established compliance by application of background or statewide standards. Groundwater ingestion and soil ingestion pathway standards under this rule must be evaluated. Surface water and air quality standards under subrules 136.6(7) and 137.6(8) must be met whenever exposure concerns are evident and the participant or the department determines these pathways may present an unacceptable risk for current or future exposures. This rule is not intended to preclude the department or the participant from addressing other exposure pathways, and the department expressly reserves the right to require evaluation of other exposure pathways and compliance with site-specific standards developed for them such as: dermal contact, ingestion of vegetables containing contaminants from soil or irrigation water, migration of contaminants from groundwater or soil into water distribution lines or into air in a confined space, migration of contaminants from soil to groundwater, and migration of contaminants in a nonprotected groundwater source to a protected groundwater source. Participants must establish compliance with standards applicable to all exposure pathways required by the department under this rule in order to qualify for no further action classification under rule 137.11(455H) unless granted a variance as provided in Iowa Code section 455H.205.
b. Site-specific standards are subject to the approval of the department. Assurances in the form of technological or institutional controls (rule 137.7(455H)) will be required, as needed, to ensure continued protectiveness of site-specific standards.
c. The following subrules provide options for the site-specific standards. The participant may select any of these options, or combinations thereof, for use as site-specific standards.
137.6(3) Site-specific groundwater point of exposure. A site-specific groundwater standard may be an appropriate target level applied at groundwater points of exposure that are limited by technological or institutional controls.
a. A point of exposure for groundwater is a location within the affected area where a well exists or could be placed (potential point of exposure). Where technological or institutional controls are determined to effectively restrict the placement of groundwater wells, the points of exposure apply outside the area of restriction. A sufficient number of points of exposure may be established for determining compliance such that compliance with appropriate target levels at these points will ensure compliance at all points of exposure. Normally a compliance point of exposure will be a location at the boundary of the area restricted by an institutional control where a groundwater well could be installed that would have the highest contaminant concentration. Generally more than one compliance point of exposure must be established due to uncertainties, such as spatial and temporal variabilities in groundwater flow and contaminant occurrence.
b. Target levels. The point of exposure target level for drinking water wells is the statewide standard applicable to groundwater ingestion or an alternative site-specific target level approved under subrule 137.6(9) or 137.6(10). The point of exposure target level for non-drinking water wells is the statewide standard applicable to nonprotected groundwater or an alternative site-specific target level approved under subrule 137.6(9) or 137.6(10). The point of exposure target level for nonused groundwater meeting the conditions in subrule 137.6(5) is the statewide standard for a nonprotected groundwater source.
c. Nonprotected groundwater sources. A nonprotected groundwater source which is affecting or likely to affect an existing drinking water well shall be required to meet the same site-specific standards, including point of exposure target level(s), as applied to a protected groundwater source.
d. Unless conditions can be demonstrated to be stable, predictive techniques in accordance with subrule 137.9(4) must be used to determine the future effects of groundwater contamination on existing drinking and non-drinking water wells and to determine the area predicted to exceed the point of exposure target level(s) where wells could be installed. When using predictive techniques, determining the location(s) where the applicable point of exposure target level is expected to be exceeded may involve comparison of the appropriate numerical standard to the predicted contaminant concentration at a passive monitoring well at the groundwater point of exposure. Alternatively, predictive techniques using site-specific models (paragraph 137.9(4)"b") may involve simulation of pumping at a well located at the point of exposure, in which case, the pumping rate used in the simulation shall be the rate that is reasonably possible for the area that yields water with the highest contaminant concentration. In absence of site-specific justification for doing otherwise, long-term pumping will be assumed to be at a rate of 100 gallons per day; the sustainable yield, if less than 100 gallons per day; or a reasonable, higher rate, if such a rate results in higher contaminant concentration.
e. Institutional controls. For a protected groundwater source or a nonprotected groundwater source as described in paragraph "b" above, institutional controls must be shown to effectively prohibit the installation of wells for the period of time in which contaminant concentrations might otherwise be expected to result in an exceedance of the appropriate target levels. For a nonprotected groundwater not described as in paragraph "b" above, a less stringent standard of effectiveness as well as the type of future well installation to be restricted may be utilized for those areas of potential concern. Unless there is a history of usage of what might otherwise be considered nonprotected groundwater or there is uncertainty as to the uniformity in the hydraulic characteristics of the nonprotected groundwater source, notice to the authority responsible for permitting private wells under 567--Chapters 39 and 49 may be adequate especially if combined with a municipal or county ordinance prohibiting installation of private wells based on the availability of a public water supply.
137.6(4) Site-specific groundwater point of compliance. A site-specific standard may be established for a site-specific groundwater point of compliance that is different from a compliance point of exposure. A site-specific groundwater point of compliance must be used in conjunction with all groundwater compliance points of exposure pursuant to subrule 137.6(3) to provide an alternative monitoring location. Target levels for contaminants of concern at a site-specific groundwater point of compliance must be established using predictive techniques as specified in subrule 137.9(4). A target level established for a groundwater point of compliance must ensure that the appropriate target level at the groundwater compliance points of exposure will be achieved. A groundwater point of compliance shall be located on the contaminant migration path from the contaminant source to the point of exposure to the maximum extent practicable.
137.6(5) Nonused groundwater in a protected water source. Statewide standards for groundwater in a nonprotected groundwater source, pursuant to paragraph 137.5(4)"b," may be used as target levels for contaminants in an otherwise protected groundwater source when groundwater in the affected area is not used and is not likely to be used in the future in accordance with the following. It must be demonstrated to the satisfaction of the department that contaminants from the enrolled site do not currently, and likely will not in the future, have an impact on any existing water supply well. Any detection, or predicted detection above the practical quantification limit, of a chemical that can be attributed to a release from the enrolled site will be considered to constitute an impact. Location of an affected area and potentially affected area outside of the wellhead protection area of any public water supply will normally satisfy this requirement with respect to public water supplies. A location within a wellhead protection area does not necessarily preclude use of nonused groundwater standards if it can be demonstrated to the satisfaction of the department that the associated public water supply will not be affected by contaminants from the enrolled site. In addition, it must be demonstrated to the satisfaction of the department that the impacted or potentially impacted aquifer is not a locally significant water resource. Factors that will go into this determination may include, but are not limited to:

* Existence of a nonimpacted public water supply in the potentially affected area;

* General availability of other water resources in the vicinity;

* Plans for development of public water supplies in the vicinity;

* Potential for use of the impacted aquifer as a water supply (e.g., yield, natural water quality); and

* Identification of the aquifer(s) commonly used for water supply in the vicinity.
A local ordinance prohibiting installation of private drinking water wells or notification to the local water utility and water permitting authority, or both, may constitute acceptable institutional controls for site-specific standards under this subrule.
The target levels that may be used in accordance with this subrule are based solely on groundwater ingestion. Compliance with this site-specific standard will not guarantee that contaminants in groundwater may not cause unacceptable exposure via other pathways (e.g., groundwater to air in a confined space, groundwater to surface water, or groundwater to a water distribution line).
137.6(6) Site-specific soil standards based on land use and soil depth. Site-specific soil standards based on land use and soil depth may be used in conjunction with institutional controls. Predetermined site-specific soil exposures based on residential, nonresidential, and restricted-access land use and soil depth are provided in the following paragraphs. Lists of resulting site-specific soil standards for these land use and soil depth categories will be maintained by the department in a guidance document and made readily available to the public. Use of these site-specific soil standards must be supported by institutional controls that ensure that land use will not change to a land use that has a larger potential exposure to soil than land use which forms the basis for the standard being used. Site-specific soil standards based on land use and soil depth, as described herein, address only ingestion of soil. Compliance with these standards will not guarantee that contaminants in soils may not cause unacceptable exposure via other pathways (e.g., ecological exposure, dermal contact with soil, soil to groundwater, soil to confined air space).
a. Deep soil in a residential land-use area. Site-specific soil standards for deep soils equaling ten times the statewide standard for soils, except for lead, may be used. The lead standard for deep, residential soils is 800 mg/kg. Soils at a depth of ten feet and greater will normally be classified as deep soils. The department may deny the use of a deep soil standard associated with a residential land use or require a modification to the standard due to site-specific considerations including topography, development potential, and actual development plans. In lieu of this default site-specific lead standard for deep soil, a site-specific standard for lead in deep soil may be calculated using the most current version of EPA's Exposure Model for Assessing Risk Associated with Adult Exposures to Lead in Soil. The use of a site-specific standard for deep soil in a residential land-use area shall be supported by an institutional control that permanently records the existence of contaminants above statewide standards in deep soils and restricts excavation resulting in deep soils being placed on the surface.
b. Nonresidential land use. The nonresidential land-use designation will be applicable to areas that are not classified as residential. Site-specific soil standards, except for lead, for nonresidential areas are based on Formula I using the risk and exposure factors shown in Table I. Site-specific soil standards for lead in a nonresidential land-use area are 400, 800, and 1,600 mg/kg for soils less than 2, 2-10, and greater than 10 feet deep, respectively. In lieu of these default site-specific lead standards, site-specific standards for lead in soil less than 2 feet deep may be calculated using the most current version of EPA's Integrated Exposure Uptake Biokinetic Model for Lead in Children. Lead in soil 2-10 feet deep may be calculated using the most current version of EPA's Exposure Model for Assessing Risk Associated with Adult Exposures to Lead in Soil with a multiple factor of 2 applied to this result for lead standards in soil greater than 10 feet deep. The use of a nonresidential land-use classification must be supported by an environmental protection easement that prevents a change in land use to residential.

c. Restricted access land use. The restricted access land-use designation will be applicable to nonresidential areas where access is physically limited (e.g., fenced-in, covered with buildings or pavement, remote location). Site-specific soil standards, except for lead, for restricted access locations are based on Formula I using risk and exposure factors shown in Table II. Site-specific soil standards for lead at restricted access locations are 800, 1,600 and 3,200 mg/kg for soils less than 2, 2-10, and greater than 10 feet deep, respectively. In lieu of these default site-specific lead standards, site-specific standards for lead in soil less than 2 feet deep may be calculated using the most current version of EPA's Exposure Model for Assessing Risk Associated with Adult Exposures to Lead in Soil with multiple factors of 2 and 4 applied to this result for lead standards in soil 2-10 and greater than 10 feet deep, respectively. The use of a restricted access land-use classification must be supported by an environmental easement that prevents a change in land use to residential and ensures that the access restrictions will be maintained.

137.6(7) Site-specific surface water standards. The department will establish site-specific surface water standards at the request of the participant. The participant shall provide the department with information necessary to make this determination upon request from the department. Site-specific surface water standards will be generally equivalent to effluent limitations under a National Pollutant Discharge Elimination System (NPDES) permit pursuant to 567-- Chapter 62. Mixing zones and allocation of contaminant loads in a surface water body will be considerations in attainment of in-stream water quality standards. If the site-specific surface water quality standards are met, best practical control technology currently available will not be imposed.
137.6(8) Site-specific air standards. If there are air quality concerns at a site, they will normally be addressed with site-specific standards until such time as ambient air quality or source-specific standards are adopted for hazardous air pollutants.
a. Explosivity. In no case shall contaminants from the enrolled site cause an explosivity level in a confined space of greater than 10 percent of the lower explosivity limit.
b. Background. In addition to the establishment of a background standard pursuant to rule 137.4(455H), a site-specific air standard may be set at twice the typical background level based on published information for a comparable setting, if approved by the department.
c. Health risk. Where applicable, the U.S. Department of Labor Occupational Safety and Health Administration (OSHA) 8-hour time-weighted-average limits for air contaminants pursuant to 29 CFR 1910.1000 may be utilized for site-specific standards with an appropriate site-specific adjustment to account for uncertainties. As a default, the adjustment shall consist of dividing the OSHA standard by a factor of 10. For locations where OSHA standards are not applicable, site-specific standards for air in a confined space shall be risk-based using the chemical-specific toxicity values of inhalation unit risk (UR) and inhalation reference concentration (RfC) determined in accordance with paragraph 137.5(3)"c" for Group A and B and Group C, D, and E chemicals, respectively. Formulas II and III shall be used to calculate risk-based, site-specific air standards for Group A and B and Group C, D, and E chemicals, respectively, where C is the risk-based contaminant concentration in air.

The Iowa Department of Natural Resources accepts the grant of this easement by signature of the Director.
________________________________________
Larry J. Wilson
Director, Iowa Department of Natural Resources
Signed this ____ day of ________________, 199_.

This document certifies that response actions to address environmental contamination have been undertaken on portions of the referenced property or properties ("the site"). It has been demonstrated that the environmental conditions at the site have met the standards of the Iowa Land Recycling and Response Action Standards program in accordance with Iowa Department of Natural Resources (IDNR) rules in Chapter 137 Iowa Administrative Code (IAC) and Iowa Code Chapter 455H. Therefore, no further environmental response action is required at this site except as described below and subject to such changes in circumstances which could authorize reopening regulation of the site in accordance with Iowa Code Chapter 455H and department rules:
ISSUED TO: [NAMES OF ALL PARTICIPANTS]
DATE OF ISSUANCE: [***]
IDNR FILE REFERENCES: [***]

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