PROPOSED RULEMAKING
ENVIRONMENTAL QUALITY BOARD
[25 PA. CODE CH. 250]
Administration of the Land Recycling Program
[26 Pa.B. 3985] The Environmental Quality Board (Board) proposes to adopt Chapter 250 (relating to the administration of the land recycling program) to read as set forth in Annex A. The proposed regulations implement the Land Recycling and Environmental Remediation Standards Act (Act 2) (35 P. S. §§ 6026.101--6026.908) by creating subchapters to establish general provisions, cleanup standards, requirements for special industrial areas, risk assessment requirements and requirements for the attainment of cleanup standards.
This proposal was adopted by the Board at its meeting of July 16, 1996.
A. Effective Date
These proposed regulations will go into effect upon publication in the Pennsylvania Bulletin as final rulemaking.
B. Contact Persons
For further information, contact Thomas K. Fidler, Chief, Land Recycling and Cleanup Program, P. O. Box 8471, Rachel Carson State Office Building, Harrisburg, PA 17105-8471, telephone (717) 783-7816; or Michelle M. Moses, Assistant Counsel, Bureau of Regulatory Counsel, P. O. Box 8464, Rachel Carson State Office Building, Harrisburg, PA 17105-8464, telephone (717) 787-7060. Information regarding submitting comments on this proposal appears in Section J of this Preamble. Persons with a disability may use the AT&T Relay Service by calling (800) 654-5984 (TDD users) or (800) 654-5988 (voice users) and request that they relay the call. This proposal is available electronically through the Department of Environmental Protection (Department) Web site (http://www.dep.state.pa.us). (Choose public participation center.)
C. Statutory Authority
This proposed rulemaking is being made under the authority of sections 104(a), 301(c) and 303(a) of Act 2 (35 P. S. §§ 6026.104(a), 6026.301(c) and 6026.303(a)). Section 104(a) of Act 2 authorizes the Board to adopt statewide health standards, appropriate mathematically valid statistical tests to define compliance with Act 2 and other regulations that may be needed to implement the provisions of Act 2. Section 301(c) of Act 2 authorizes the Department to establish by regulation procedures for determining attainment of remediation standards when practical quantitation limits set by the United States Environmental Protection Agency (EPA) have a health risk that is greater than the risk levels established in Act 2. Section 303(a) of Act 2 authorizes the Board to promulgate statewide health standards for regulated substances for each environmental medium and methods used to calculate the statewide health standards. This proposed rulemaking also is being made under the authority of section 105(a) of the Solid Waste Management Act (SWMA) (35 P. S. § 6018.105(a)). Section 105(a) of the SWMA grants the Board the power and duty to adopt the rules and regulations of the Department to carry out the provisions of the SWMA.
D. Background and Purpose
The proposed regulations were developed to implement Act 2, which became effective July 19, 1995. Act 2 establishes a framework for developing remediation standards that can be applied to any release of regulated substances. Regulated substances include hazardous substances and contaminants regulated under the SWMA, the Hazardous Sites Cleanup Act (HSCA) (35 P. S. §§ 6020.101--6020.1304), the Air Pollution Control Act (APCA) (35 P. S. §§ 4001--4015), The Clean Streams Law (CSL) (35 P. S. §§ 691.1--691.1001), the Storage Tank and Spill Prevention Act (STSPA) (35 P. S. §§ 6020.101--6020.2105) and the Infectious and Chemotherapeutic Waste Act (ICWA) (35 P. S. §§ 6019.1--6019.6). The environmental remediation standards established under Act 2 must be used whenever a site remediation is voluntarily conducted or is required to be conducted under one of the laws previously stated, in order to qualify for a release of liability. The proposed regulations will encourage the recycling and redevelopment of industrial sites, the preservation of existing uses of land and will encourage persons to perform cleanups by providing the opportunity for a release of liability. The Act 2 program is currently operating and 100 sites are participating.
A person who intends to perform a remediation in accordance with Act 2 should consult the statute, these proposed regulations and the Land Recycling Technical Guidance Manual (Manual) developed by the Department. In accordance with Governor Ridge's Executive Order 1996-1, the Department has taken a minimalist approach to developing these proposed regulations. Subjects that are clear and unambiguous in the statute are not repeated in these proposed regulations. In addition, when possible, the Department has chosen to use nonregulatory alternatives, such as the Manual, for points of clarification rather than building those into the proposed regulations. For example, procedural requirements such as deed notices or notices of intent to remediate (NIR) are addressed more directly in the statute or the Manual. The proposed regulations do address limited issues concerning procedures, such as what must be contained in plans and reports that are submitted to the Department. Compliance with procedural requirements in the statute and the proposed regulations is required in order to meet a remediation standard. Appropriate uses of engineering or institutional controls with regard to the specific remediation standards and permit waivers are addressed in the statute, not the proposed regulations.
Chapter 5 of Act 2 (35 P. S. §§ 6026.501--6026.506) affords liability protection from further cleanup obligations if a person demonstrates compliance with any, or a combination, of the three environmental remediation standards: the background standard; Statewide health standard; and site-specific standard. Act 2 also affords liability protection for the remediation of special industrial areas. In order to receive the liability protection, a person must comply with the requirements of Act 2 and the proposed regulations, including the administrative requirements, unless the site is placed on the Pennsylvania Priority List under HSCA or the release is subject to the corrective action regulations of the STSPA. In these two cases, persons shall comply with the cleanup levels as described in Act 2 and this chapter and the administrative requirements of HSCA or STSPA in order to qualify for liability protection. A person who is eligible for cleanup liability protection will be relieved of further liability for remediation of the site for contamination identified in the required reports and will not be subject to citizen suits or contribution actions brought by responsible parties under Pennsylvania law.
An important element to any remediation is the site characterization or remedial investigation. A thorough investigation of the site is necessary to identify specific contaminant concentrations, the extent of contamination throughout soil and groundwater media, discharges to surface water and site conditions that may pose an unacceptable human health or environmental risk. It is important to perform a thorough investigation because the relief from liability only applies to contamination identified in reports submitted to and approved by the Department to demonstrate compliance with a standard. In the case of a special industrial area, the relief from liability applies to any contamination identified in the baseline environmental report, other than unabated immediate, direct and imminent threats to public health and the environment. The proposed regulations provide some performance criteria that must be met to properly characterize the site. A more detailed explanation of how to perform a remedial investigation, however, may be found in the Manual.
These proposed regulations address six major topics: the use of practical quantitation limits (PQLs); aquifer determinations; Statewide health cleanup standards, where no health advisory levels and no maximum contaminant levels exist; protection of ecological receptors; performance criteria for site characterizations and risk assessments; and attainment demonstrations.
Act 2 created the Cleanup Standards Scientific Advisory Board (SAB) for the purpose of assisting the Department in developing statewide health standards, determining the appropriate statistically and scientifically valid procedures to be used, determining the appropriate risk factors and providing other technical and scientific advice as needed to implement Act 2. Throughout the development of these proposed regulations, SAB and its subcommittees provided many significant technical recommendations. In addition, SAB reviewed drafts of the proposed regulations and provided comments to the Department on the drafts. The Department gratefully acknowledges the contributions of SAB to the development of these proposed regulations. Five members of SAB were selected by the Secretary of the Department and nine members were selected by the General Assembly. They are independent, outside experts in numerous scientific fields who provided their time and considerable expertise to the Department on a volunteer basis.
The Board has provided a qualified endorsement of the regulations, which is further detailed in a document entitled, ''Cleanup Standards Scientific Advisory Board Qualified Endorsement of the Act 2 Proposed Regulations,'' which is available by contacting the Department. In this document, the Board commended the representatives of the Department on the manner in which they dealt with the Board and their willingness to maintain a high level of involvement on the part of SAB in developing these proposed standards. Elements of the proposed regulations that SAB strongly endorses include the following: the means used to develop the Statewide health-based standards; the development of minimum threshold Statewide standards for substances lacking toxicity data; the development of soil-to-groundwater standards; the attainment criteria and methods included in the proposed regulations; the selection and use of PQLs; and baseline remedial investigation procedures for special industrial areas.
Elements of the proposed regulations for which SAB has some continuing concerns include the following: the required attainment of secondary maximum contaminant levels (SMCLs); the definition of sustainable yield of a significant amount of water to a well or a spring, for purposes of defining an aquifer; the Statewide standards for addressing vapor intrusion into basements; the requirement to address ecological risks under statewide health standards; and the requirement that standards below reliable quantitation limits be attained. SAB is also concerned about the classification of nonaqueous phase liquids (NAPLs) as wastes, rather than as contaminated media subject to remediation.
The Department has had a limited time to propose these regulations. The issues are complex and the Department and SAB have used new and creative concepts to deal with difficult issues such as valid characterization methods that require less sampling and the use of minimum threshold values for regulated substances for which toxicity data is unavailable. For these reasons, the Department specifically encourages thoughtful analysis and comment by interested members of the public. The Department specifically invites comments on the following issues: the interface between the solid waste requirements and the Act 2 requirements; the use and efficacy of the 75/10x statistical test; the development and use of minimum threshold medium specific concentrations and the availability of a release of liability for meeting these standards; aquifer determinations; the screening procedure for volatile compounds in indoor air; the saturation limit provided on medium-specific concentrations in soil; and the use of the ecological screening procedure as part of the Statewide health standard.
E. Summary of Regulatory Requirements
A brief description of the proposed regulations is as follows:
Subchapter A. General Provisions 1. Section 250.1. Definitions.
This section includes definitions for terms that are not found in the statute but were needed to clarify language in the statute. These terms are: ''ASTM,'' ''anisotropy,'' ''enterprise zone,'' ''heterogeneity,'' ''MCL,'' ''MSC,'' ''NIR,'' ''NPDES,'' ''PQL,'' ''property,'' ''risk assessment,'' ''SIA--special industrial area,'' ''site'' and ''TF.'' The term ''volatile compound'' is defined to limit the number of regulated substances that have to be evaluated for human exposure from inhalation and volatilization for the soil and groundwater pathways.
2. Section 250.2. Application of remediation standards.
This section explains the requirement that remediations performed under an enforcement action meet one of the three cleanup standards--background, Statewide health or site-specific. It also states that requirements and procedures under Act 2 and these regulations must be met in order to qualify for liability protection.
3. Section 250.3. Management of contaminated media.
This section explains that management of contaminated media that is removed during remediation conducted under Act 2 must be managed in accordance with the applicable waste, water quality and air laws and regulations. The Department has the discretion to waive applicable requirements for onsite remediation activities based on a written demonstration of the criteria in section 902 of Act 2 (35 P. S. § 6026.902).
4. Section 250.4. Groundwater determinations.
This section explains when a regulated substance, that is in contact with groundwater, is considered contaminated media subject to the cleanup standards of Act 2, and when it is considered waste, subject to regulation under the applicable waste laws and regulations. Here again, the Department has the discretion to waive applicable requirements for onsite remediation activities based on a written demonstration of the criteria in section 902 of Act 2. This provision applies to groundwater remediations where LNAPLs (light nonaqueous phase liquids) and DNAPLs (dense nonaqueous phase liquids) exist in subsurface soils.
5. Section 250.5. Aquifer determinations.
This section explains elements of the statutory definition of the term ''aquifer,'' such as ''significant amount'' and ''sustainable yield,'' which were not defined by the statute. This section will be used to determine which pathways of exposure are relevant for consideration in developing Statewide health and site-specific standards for groundwater. Groundwater in an aquifer is afforded a higher level of protection under Act 2.
6. Section 250.6. Current use and future use of aquifer groundwater.
This section explains phrases in the statute, related to groundwater in aquifers, that were left undefined. These phrases are ''currently planned for future use'' and ''probable future use.'' Under Act 2, current drinking or agricultural uses of groundwater and certain future uses of groundwater in an aquifer are afforded the same protection. This section describes which future uses are protected. Future uses of groundwater in an aquifer are protected if three requirements are met: public or private water supplies can be expected to rely on groundwater in the vicinity of the site where the contamination is expected to migrate; background water quality is such that it can be used for drinking water or agricultural purposes, or both, with reasonable treatment; and no other factors, such as local ordinance restrictions or deed restrictions, exist that would prevent the use of the groundwater in the vicinity of the site where the contamination is expected to migrate. As previously used, the phrase ''where the contamination is expected to migrate'' should also address situations involving geologic features present that would prevent the flow of groundwater.
7. Section 250.7. Standards relating to PQLs
This section establishes the source for identification of PQLs for regulated substances in soil and groundwater. Under Act 2, the PQL value may be used as a default value in lieu of a background value determined through a site investigation. Also, PQLs are considered threshold concentration levels for establishing Statewide health and site-specific standards. However, PQLs may not be used as cleanup standards in the following instances: (1) PQLs that fall outside the maximum allowable health risk levels identified in sections 303(c) and 304(b) and (c) of Act 2 (35 P. S. §§ 6026.303(c) and 6026.304(b) and (c)) may not be used; (2) if maximum contaminant level (MCL) has been promulgated under the Pennsylvania Safe Drinking Water Act (35 P. S. §§ 721.1--721.17) for the regulated substance; and (3) if a lifetime health advisory level (HAL) has been established under the safe drinking water program.
This section also clarifies that the selection of methods to analyze samples of environmental media is not restricted to the source methods of the PQLs.
8. Section 250.8. Public notice by applicant.
This section explains when the opportunity to request public participation is initiated. For cleanups under the site-specific standard and special industrial areas (SIAs), the notice of intent to remediate must include a 30-day period in which the municipality, where the remediation site is located, may request to be involved in the development of the remediation and reuse plans for the site. No plans and reports associated with the remediation may be submitted to the Department prior to the end of that 30-day period.
9. Section 250.9. Public participation.
This section establishes the starting date for the commencement of the 30-day public and municipal comment period during which a municipality may request to be involved in the development of the remediation and reuse plans. The comment period will begin on the publication date of the summary of the NIR in a newspaper of general circulation. This section also provides minimum contents for a public involvement plan and requires submission of the plan with the first report due to the Department for either a site-specific standard or special industrial area cleanup.
10. Section 250.10. Fees.
This section provides that resubmissions of reports and plans, except for a site-specific standard final report, require payments of the appropriate fee identified in Act 2. The section also states that the Department will disapprove a plan or report that is submitted without the appropriate fee.
11. Section 250.11. Publication.
This section creates the obligation for the Department to publish notice of its final actions on plans and reports in the Pennsylvania Bulletin. Appeals from Department actions are governed by the Environmental Hearing Board.
12. Section 250.12. Applicability to solid waste facilities.
This section explains how the Act 2 cleanup standards apply to solid waste facilities. Performance standards that exist in the solid waste regulations, such as how and where to monitor for contamination or how to demonstrate eligibility for a waiver or modification of liner and leachate treatment systems as part of a permit modification, will continue to apply to new and operating solid waste facilities.
A release at an old facility must be remediated to one of the three Act 2 standards, at the points of compliance identified in these proposed regulations.
A release at a new facility must be remediated to background at the points at which the facility must have monitoring wells under the pertinent solid waste regulations.
A release at a mixed facility, which received waste on or before, and after a trigger date, must be remediated to meet Act 2 standards, but must do so at the monitoring points identified in the pertinent solid waste regulations.
These proposed regulations only affect the levels in contaminated media that must be attained. It does not affect all the other requirements for facilities regulated under the SWMA.
The Department specifically invites comments on the interaction of Act 2 and the SWMA, and its effect on facilities presently operating under the hazardous, residual or municipal waste regulations.
13. Section 250.13. Measurement of regulated substances in media.
This section sets out procedures for sampling regulated substances. To eliminate differences based on moisture content, it provides that analyses of soils and sediments must be done on a dry weight basis.
It also requires total metals analysis for most substances in soil, and requires field filtering and field acidification of groundwater samples for metals analysis.
Subchapter B. Background Standard The background standard is one of the three cleanup standards available under Act 2. ''Background'' is defined by Act 2 as the concentration of a regulated substance determined by appropriate statistical methods that is present at the site, but is not related to the release of regulated substances at the site. The determination of a background concentration can be based on levels of naturally occurring substances and concentrations of regulated substances originating from sources on other properties. Under Act 2, persons are not responsible for abating releases originating from other properties.
Institutional controls cannot be used to attain the background standard. Deed notices are not required if the background standard is attained and prior deed notices may be removed.
1. Section 250.202. Establishing background concentrations.
Background standards can be determined using two methods. First, a person can use practical quantitation limits as the default background standard. Second, a person can use a remedial investigation to establish background. If a person uses a remedial investigation to establish background, samples must be taken in an area unaffected by a release on the property. In some cases, this may require off-property sampling. Criteria is included in order to determine the number of samples necessary to determine background levels in groundwater.
2. Section 250.203. Points of compliance.
The point of compliance is the location in the environmental media where attainment of the standard must be met. The points of compliance for surface water and air quality are the same for all three cleanup standards. In surface water, the following points of compliance apply: (1) point source discharges must meet limits specified in a National Pollution Discharge Elimination System (NPDES) permit; (2) nonpoint source or diffuse groundwater discharges to surface water must meet surface water quality standards through the use of mass balance techniques; and (3) when groundwater discharges to the surface, thus creating a spring, the point of discharge to the surface is the point of compliance. For outdoor air quality, the point of compliance is what is specified in the air quality regulations. To attain the background standard for groundwater, the point of compliance is throughout the contaminant plume, including areas of the plume that are outside the property boundary. For soil, the point of compliance for the background standard is throughout the area of the soil that has become contaminated as a result of releases on the property.
3. Section 250.204. Final report.
Under the background standard, the final report is the only report that must be submitted to and approved by the Department. The final report must document the following: site investigation activities including all laboratory results; the means for establishing background concentrations; the remediation activities; the demonstration of attainment with the standard; and any post-remediation activities, such as engineering or institutional controls, that are necessary to maintain attainment.
Subchapter C. Statewide Health Standards The Statewide health standard is one of the three cleanup standards available under Act 2. The statewide health standards were developed in consultation with SAB, established by Act 2. Act 2 mandates the use of HALs and other health-based standards, including MCLs, adopted by the Department and by the Federal government by regulation or statute for statewide health standards. This rulemaking introduces the health-based standards adopted by the Department. The medium-specific concentrations (MSCs) included in Appendix A, Tables 1 and 2 are the concentrations that must be met in order to demonstrate attainment of a Statewide health standard, along with a separate screening procedure for the volatilization of a subset of regulated substances into indoor air and the protection of ecological receptors.
The Department and SAB agreed that a saturation limit on MSCs for soil is needed. Although the ingestion and inhalation numeric values reflect the 1 × 10-5 cancer risk level, in some cases at these concentrations the soil could be more than 100% saturated with regulated substances. Therefore, a numerical cap of 190,000 ppm has been proposed as the saturation limit in soils.
In order to select the appropriate concentration from Appendix A, Tables 1 and 2, determinations must be made concerning the land use of the property, the background groundwater quality of the aquifer for total dissolved solids, saturation or unsaturation of the soils and depth of the soil contamination.
Based on SAB's recommendation and the Department's concurrence, the Department is proposing the use of a cancer risk factor of 1 × 10-5 for the development of soil and groundwater MSCs. The formula ''1 × 10-5'' means there is an excess cancer risk of 1 in 100,000 in the human population. This risk factor was chosen because it falls midway within the risk range identified in Act 2, and it has been adopted by several other states, including California, Indiana, the Commonwealth of Massachusetts and Michigan, for use in the development of cleanup standards. Act 2 mandates that MSCs for carcinogens must be based on an upper bound lifetime cancer target risk of between 1 in 10,000 and 1 in 1 million.
Based on SAB's recommendation and the Department's concurrence, the Department is not proposing to develop soil and groundwater standards based on the dermal absorption route of exposure. Soils contaminated by regulated substances that meet ingestion and inhalation based standards would not pose a substantive risk because of low bioavailability, low moisture content of surface soils and short exposure periods for actual adherence of soil to the skin. For sediments, exposure is less frequent and of shorter duration than soils. For groundwater, the ingestion and inhalation standards provide adequate protection from the dermal contact route of exposure.
If the Statewide health standard is numerically less than the background standard for a regulated substance on a given site, then the background standard or the PQL must be used.
The proposed statewide health standards are protective of human health. SAB and the Department were unable to develop standards that are also protective of the environment. The complexity of how different substances interact with different species makes it very difficult to establish statewide health standards protective of ecosystems in general. Therefore, the Department is proposing a screening procedure to evaluate the effects of regulated substances on potential ecological receptors. The Department is specifically seeking comments on how these proposed regulations address ecological receptors.
SAB and the Department were unable to identify a generic method by which to adequately simulate the movement of vapors from soil and groundwater to indoor air. This is due to the varying construction methods and materials and integrity of subterranean structures. The proposed regulations contain a screening process which identifies chemicals and situations of concern that would trigger the remediator to evaluate and abate the risk under either the background standard or the site-specific standard. The Department is specifically seeking comments on how these proposed regulations address volatilization of regulated substances into indoor air.
1. Section 250.301. Scope.
This section explains that the statewide health standards are addressed in Subchapter C. References to the appropriate tables for choosing a Statewide health standard are included.
2. Section 250.302. Point of compliance.
The points of compliance for surface water and outdoor air quality are the same as those identified above under the background standard. For the ingestion and inhalation standards developed for groundwater, the point of compliance is at and beyond the property boundary that existed at the time the contamination is discovered or such point beyond the property boundary that the Department may determine to be appropriate under certain specific situations identified in this section. For instance, the Department may move a point of compliance where the contamination goes beyond a property boundary if those substances are secondary contaminants. The point of compliance for soil is the concentration of the medium specific value at the depth specified in § 250.304 (relating to MSCs for soil).
3. Section 250.303. MSCs for groundwater.
For groundwater in aquifers, the MSCs are developed on the basis of the following hierarchy: (1) the use of MCLs; (2) where no MCL has been established, the use of lifetime HALs; (3) where no MCL or HAL exists, the use of the lowest concentration calculated used in the equations in §§ 250.305 and 250.306 (relating to ingestion numeric values; and inhalation numeric values). Sites with groundwater that naturally exceeds 2,500 milligrams per liter for total dissolved solids may use an adjusted Statewide health standard. If this situation is occurring at a given site, the adjusted Statewide health standard shall be used as the basis for the development of a soil standard that is protective of groundwater.
SAB and the Department were unable to develop generic statewide health standards to address the volatilization of regulated substances from groundwater through soils to indoor air. SAB identified three substances (carbon tetrachloride, 1,1 dichloroethene and vinyl chloride) and the Department added three substances (1,2, dichloroethane, benzene and chloroform) for screening volatile compounds, on the basis of volatilization and toxicity to humans that may be of concern at the point of exposure in below grade structures on the property. In order to quantify and abate the risk posed through this pathway, a person must use the protocols and procedures under the site-specific standard.
4. Section 250.304. MSCs for soil.
Standards for soil are developed based on residential and nonresidential land uses. Along with changes in exposure factors, the depth to which the human health standards will apply varies based on land use. The residential standards and nonresidential standards to a depth of 2 feet are protective of human health through the ingestion, inhalation and volatilization and soil to groundwater routes of exposure. The nonresidential standards at a depth of 2 to 15 feet are protective of human health through the inhalation, volatilization and soil to groundwater routes of exposure. The standards are developed to ensure that future leaching of contaminants through soil will not exceed the groundwater standard as established in § 250.303.
This section states that soil remediation to secondary MCLs is not required. This is because any drinking water that might be impacted by the released substance would be abated prior to the point of use.
In order to determine the depth which the ingestion and inhalation standards apply, SAB recommended and the Department agreed that the depth should vary based on land use patterns and deed notice provisions. For the residential land uses, a person must remediate to the full depth of 15 feet from the existing ground surface. For nonresidential land uses, a person must remediate to a depth of 2 feet from the existing ground surface. Contamination below this 2-foot level will be documented in the deed notice.
This section establishes a soils saturation cap for MSCs for soil. The following saturation cap was adopted based on a SAB recommendation. A physical limitation on the concentration of a regulated substance that could occur in soil was calculated to serve as an upper limit for direct contact MSCs in soil. This physical limitation is based on an assumed porosity for the soil equal to 0.35, an assumed dry bulk density of soil equal to 1.8 kg/L and an assumed regulated substance density of 1.0 kg/L. This combination of assumptions yields a dry soil basis concentration limit of 190,000 mg/kg based on the equation in this section of the proposed regulations.
Other options were considered by the Department for development of a saturation cap. A Department proposal for capping the MSC was to base the cap on the organic carbon content of the soil. For example, the cap would limit each organic regulated substance in soil to the naturally-occurring organic carbon content of the soil. This approach is premised on the concept that a given mass of organic carbon in soil can not sorb a mass of organic contamination which is greater than the mass of naturally occurring organic carbon. An organic carbon content ranging from 0.25% to 4% could be used. This would yield a cap for organic regulated substances within the range of 2,500 mg/kg to 40,000 mg/kg. A second SAB proposal was to choose an arbitrary upper bound limit, between 10,000 and 50,000 ppm, based upon analytical precision for environmental testing methods. Above these levels, dilution errors and signal/noise levels cause large relative imprecision. The Department is seeking comments on the method proposed and on other methods to develop a saturation cap.
5. Sections 250.305 and 250.306. Ingestion Numeric Values and Inhalation Numeric Values.
The algorithms or equations in these sections are based on those presented in EPA's risk assessment guidance for the Superfund program, under the Comprehensive Environmental Response, Compensation and Liability Act (42 U.S.C.A. §§ 9601--9675). The equations attempt to replicate how the average person is expected to come into contact with regulated substances in soil or groundwater and how the contact will impact human health. The equations include consideration of assumptions as to body weight, exposure frequency and duration, inhalation and ingestion rates and toxicity data. The protection goals of section 303 of Act 2 are built into the equations.
Except in the following cases, EPA's generic exposure assumptions were used. Residential exposure to carcinogens is based on combined childhood and adult exposure. The EPA uses a residential exposure frequency of 350 days, accounting for time away from home. SAB recommended and the Department agreed, to reduce the exposure assumption to 250 days to reflect the number of days when the soil is frozen and volatilization is minimized. Similarly, SAB recommended, and the Department agreed, to calculate the nonresidential standards by assuming work weeks of 5 days, and multiplying 250 days by 5/7. The EPA uses an exposure frequency of 350 multiplied by 5/7. SAB recommended and the Department agreed to use the soil ingestion rate in its Manual, which had been based on EPA's Resource Conservation and Recovery Act of 1976 (RCRA) (42 U.S.C.A. §§ 6901--6986) corrective action proposal. The Department is using different nonresidential inhalation numbers than EPA, on SAB's recommendation, to reflect reduced activity and inhalation rates indoors. The proposed inhalation numbers are lower than the EPA's because SAB believes that the lower number is a more realistic breathing rate for a workplace setting. The EPA's number is too high for sustained activity over 8 hours.
The toxicity values, oral reference dose for systemic toxicants and the oral cancer slope factor for known human carcinogens, were selected based on the following hierarchy: current EPA Integrated Risk Information System (IRIS) files; current citations in the EPA's Health Effects Assessment Summary Tables (HEAST); EPA provisional values; the Federal Agency for Toxic Substances and Disease Registry (ATSDR) toxicity profiles; recommendations by California EPA; and the EPA Ambient Water Quality Criteria documents. Where toxicity values existed for either ingestion or inhalation, but not for both, the data available for one pathway was used for the other pathway. Input parameters such as body weight, the exposure duration, the exposure frequency and averaging times may vary based on land use.
Section 250.305(f) explains the methodology for developing the ingestion numeric value for lead.
The types of toxicological data which have been used to develop direct contact soil MSCs for all of the other regulated substances listed in Appendix A, Table 2 do not exist for lead. For example, although lead is classified as a carcinogen, it possesses no cancer slope factor so that a concentration in soil which represents an excess upper bound lifetime cancer target risk of one in 100,000 cannot be estimated. Similarly, even though lead is a systemic toxicant, there are no available oral reference doses from which to develop a threshold effect level for lead. This lack of data makes it necessary to develop direct contact soil MSCs for lead in an alternate manner.
The toxicological endpoints of concern for lead differ between children and adults. Because of this, two separate methods have been used to estimate direct contact soil MSCs for lead--one for residential exposures (based on effects on children) and one for nonresidential exposures (based on effects on adults). The following text describes the methodologies employed in developing both concentrations.
The direct contact soil MSC for lead for residential exposures has been estimated on the basis of protection of 95% of a population of children in the age range of 0 to 84 months. The Uptake Biokinetic (UBK) Model for Lead (version 0.4) was used to make this estimate. Although this model has been updated at least twice since version 0.4, this version was used because it was the version in use at the time the EPA developed its recommended residential lead-in-soil level of 500 mg/kg. Appendix A, Table 6 contains the input values that have been used in the model. The soil lead level from Appendix A, Table 6 (495 ug/g) has been rounded to 500 mg/kg which is the direct contact soil MSC for lead for residential exposures.
Because the UBK Model for Lead applies only to children, it could not be used for the nonresidential exposure scenario. Alternatively, a modeling equation applicable to adult exposures developed by the Society for Environmental Geochemistry and Health (SEGH) was obtained from Wixson (1991).
6. Section 250.307. Soil to groundwater pathway numeric values.
The statute provides three mechanisms for the development of soil to groundwater pathway numeric values. Values in Appendix A, Table 1, include concentrations developed using the following: (1) a concentration which is 100 times the MSC for groundwater; and (2) for organic compounds, a concentration developed using an equilibrium partitioning coefficient method which would be protective of the MSC for groundwater. SAB and the Department were unable to identify a valid, peer-reviewed scientific method to predict the leaching of inorganic compounds from soil to groundwater. As a third option, the person remediating may use the Synthetic Precipitation Leaching Procedure in order to determine a level which would not produce a leachate in excess of the MSC for groundwater.
When using an equilibrium partitioning coefficient method for organic compounds, the dilution factor may vary based on the organic carbon partition coefficient for that substance and based on whether the soils are saturated or unsaturated. The fraction of organic carbon in soil was selected to represent average values found in this Commonwealth.
7. Section 250.308. Radionuclide numeric values.
This section explains how the statewide health standards were developed for radionuclides. The Department determined, in consultation with SAB, that the radionuclides of concern are limited to those commonly found in soil and groundwater. Therefore, a short list of isotopes was chosen for developing statewide health standards. The screening process for developing the short list was as follows. First, a survey of the radioisotopes commonly found in soil and groundwater in recent cleanup projects was considered. Second, the list was augmented by the candidate lists prepared by the Federal Nuclear Regulatory Commission (NRC) (NRC 1500 1994) and the EPA. Third, isotopes with half lives of 1 year or more were retained on the screened final list. The progeny with half lives of 6 months or more were assumed to coexist with the parent in secular equilibrium. Long-lived progeny were separately accounted for as ingrowths or, if initially present, assumed to start a chain of their own. For cases where ingrowths are significant, the year for maximum dose was selected for annual dose specification. For the pathways under consideration, the maximum dose was checked out to always occur initially, that is, at time zero. Thus, ingrowth of long-lived progeny did not introduce further complications in this project.
The exposure assumptions used for this section are essentially the same as those proposed for other sections of the statewide health standards. When new parameters were used, their basis and appropriate references are indicated in the proposed regulations.
The MSC for radionuclides was determined based on the annual effective dose equivalent of 4 millirem per year for each pathway. This is comparable to the basis of 4 millirem per year whole body dose used by the EPA for the determination of MCLs for drinking water (40 CFR 141). These levels are in general agreement with the cleanup standards recently proposed by the NRC at 59 FR 43200 (August 22, 1994) and the EPA.
8. Section 250.309. Minimum threshold MSCs.
This section provides cleanup standards for regulated substances where no toxicological data is available for the substances. The Department is seeking comments on the procedure for developing minimum threshold MSCs and on the proposed numbers for the substances identified in Appendix A, Table 4. It should be noted that these numbers are based solely on ingestion.
The standards identified for groundwater and for the soil ingestion numeric value were developed by a subcommittee of SAB. First, SAB considered the United States Food and Drug Administration's (FDA) final rule, Threshold of Regulation for Substances Used in Food-Contact Articles, 60 FR 36582 (July 17, 1995). The regulations establish threshold levels for exempting from regulation food additives that are derived from food-contact articles that migrate, or may be expected to migrate, into food (such as, food packaging and food processing equipment). In determining the threshold number, the FDA looked at a set of 477 rodent carcinogens by oral route compiled by L. S. Gold et al. By analyzing the probability density distribution of the 50% Toxic Doses (TD50) of these carcinogens, the FDA determined the concentration that represented an acceptable risk. The FDA threshold is 0.5 ppb of dietary concentration. The FDA stated that a dietary intake of 0.5 ppb of an indirect food additive would result in a risk of less than 1 × 10-6 with roughly 60% probability.
The threshold numbers have been established at a 1 × 10-5 risk level, consistent with the statewide health standards. The actual dietary intake of 0.5 ppb of the substance in food is multiplied by SAB's assumption of 2000 grams of food intake per person per day. The product of the multiplication is 1 microgram of a substance per person per day. Because the 0.5 ppb was based on a 1 × 10-6 risk level, SAB adjusted the 1 microgram (ug) to a 1 × 10-5 risk level. The result of that adjustment is 10 micrograms of a substance per person per day. To calculate the soil concentration, it is assumed that a person would ingest 100 milligrams (mg) of soil per day; therefore, the corresponding concentration in soil would be 10 ug/100 mg of soil, or 100 mg of a substance per kilogram of soil. This calculation resulted in the proposed soil ingestion numeric value of 100 mg/kg in soil. To calculate the groundwater concentration, it is assumed that a person would ingest 2 L of water per day; therefore, the corresponding concentration in water would be 10 ug/2 L, or 5 ug/L. This calculation resulted in the proposed minimum threshold MSC for water ingestion of 5 ug/L.
The minimum threshold MSC for soil is determined by selecting the lowest of the ingestion numeric value or the soil-to-groundwater numeric value as determined by the methodology in § 250.307.
The minimum threshold MSCs may be used only when no toxicological data is available for the regulated substance. If the minimum threshold MSC concentration is attained and impacts to ecological receptors are addressed in accordance with § 250.310, the Department will provide a release of liability. Under Act 2, the Department may require additional remediation for the regulated substances that meet a minimum threshold MSC if new chemical-specific toxicological information is obtained which revises the exposure assumptions beyond the acceptable risk. The Department is seeking comment on providing a release of liability for compliance with these standards.
9. Section 250.310. Evaluation of ecological receptors.
SAB and the Department were unable to identify a scientific method in the time available to develop generic statewide health standards that are protective of ecological receptors. SAB and the Department recommended a screening protocol for identification of receptors of concern, chemicals of concern and the size of sites of concern. If the screening process identifies impacts on ecological receptors that need to be addressed, the remediator must do one of the following: (1) demonstrate that attainment of the Statewide health standard is protective of the receptor; (2) demonstrate attainment with the background standard; or (3) follow the procedures in § 250.402(d) and demonstrate attainment with the site-specific standard.
If jet fuel, gasoline, kerosene, number two oil or diesel fuel is the only constituent detected onsite and is not an NAPL, the site will not require further evaluation of ecological receptors. SAB recommended this screen because it is believed that once the statewide health standards for the constituents found in the products identified above are met, the concern for ecological receptors will have been addressed. The substances listed in this screen are limited to a subset of petroleum products for which the chemical makeup and concentrations can be reliably predicted.
If, after the screening for the substances above, it is determined that 2 acres or more of surface soil or 1,000 or more square feet of sediments have been contaminated, then the screening procedure must be completed. Sites of less than 2 acres were eliminated due to the substantially greater feeding range of most ecological receptors. The size threshold for sediment areas of concern is smaller than for surface soils, based on the propensity for contaminants to concentrate as a result of differential particle size transport and sorting processes, the sedentary nature of the species making up the benthic community, and the generally greater sensitivity of many aquatic species to constituents.
If, after screening for the soils and sediments above, the contaminants at the site are constituents of potential ecological concern, then further ecological evaluation is required. The list of chemicals of potential ecological concern, contained in Appendix A, Table 7, is largely based on 67 compounds identified by EPA as toxic to ecological receptors. In addition to the 67, SAB recommended and the Department adopted the addition of four pesticides either because of their toxicity or their potential to bioaccumulate in the food chain. Those four pesticides are aldrin, chlordane, kepone and mirex. If no constituents of potential ecological concern are present, then an environmental scientist must perform a preliminary site walk evaluation to determine if there are indications of ecological impacts.
If constituents of potential ecological concern exist or if indications of ecological impacts exist, then the site must be evaluated to determine whether features such as buildings, parking lots or graveled paved areas exist. The step will determine whether exposure pathways to the receptors are eliminated. If the pathways are not eliminated, a formal site walk evaluation must be conducted by a scientist who is qualified to perform risk assessments. The results of the site walk and of exposure pathway evaluation will determine which ecological impacts must be addressed.
Initially, the screening process is elementary to allow a person not thoroughly versed in ecological assessment protocols to determine whether there is a problem of concern. If such a problem is identified, then an expert in the field of ecological risk assessment must be utilized.
10. Section 250.311. Final report.
Under the Statewide health standard, the final report is the only report that must be submitted to and approved by the Department. The final report must document the site investigation activities including all laboratory results, the remediation activities, the demonstration of attainment with the standard and any post-remediation activities, such as engineering or institutional controls, that are necessary to maintain attainment. The final report must also include information supporting the use of residential or nonresidential standards.
Subchapter D. Site-Specific Standard 1. Section 250.401. Scope.
This section clarifies that the Department may approve or disapprove the plan and reports submitted under the site-specific standard based on the criteria listed in section 304 of Act 2.
2. Section 250.402. Human health and environmental protection goals.
This section defines the level of protection that is afforded to humans from threats posed by soil and groundwater contaminated with regulated substances which are known or suspected carcinogens or systemic toxicants. Remedies under the site-specific standard must also address cumulative risk.
Also included is the process by which risks to ecological receptors are assessed and addressed. This process requires use of the ecological screening protocol developed for the Statewide health standard and use of current EPA or American Society for Testing and Materials (ASTM) guidances to quantify the risk to ecological receptors.
3. Section 250.403. Use of groundwater in an aquifer.
Groundwater that has naturally occurring total dissolved solids above 2,500 ppm will not be considered a drinking water source in accordance with Act 2.
Current and future uses of groundwater in aquifers under the site-specific standard are to be determined in accordance with the definition of those uses in § 250.6.
This section requires compliance with MCLs, at a minimum, in order to protect the use of groundwater for drinking water purposes.
4. Section 250.404. Pathway identification and elimination.
This section requires the use of the most recent EPA or ASTM guidance in order to identify potential current and future exposure pathways to humans and ecological receptors. Future land use of the site and the effect of institutional and engineered controls should be taken into consideration in determining whether an exposure pathway is relevant. Exposure pathways include ingestion, inhalation of volatiles and particulates. The dermal contact route of exposure is not required to be evaluated because this risk is nominal compared to the risk posed by ingestion and inhalation and will be subsumed by the standards developed for these pathways.
5. Section 250.405. When to perform a risk assessment.
Persons who choose to develop a site-specific standard, or concentration level, must do so by conducting a risk assessment under Subchapter F.
Submission of a baseline risk assessment report is not required where it can be demonstrated in the remedial investigation report or cleanup plan that there are no current or future exposure pathways or where identified current or future pathways are eliminated through the implementation of a specific remediation measure. These remediation measures must be proposed to the Department in a cleanup plan prior to implementation.
6. Section 250.406. Point of compliance.
The points of compliance for the site-specific standard are identical to those used for the Statewide health standard for: releases to outdoor air, surface water and springs; ingestion and inhalation threats from contaminated groundwater; soil-to-groundwater soil standards; and soil standards developed to protect from threats posed by ingestion and inhalation in residential land use settings.
This section establishes the point of compliance for volatilization from soils and groundwater to indoor air as the point of exposure on the property in a below grade occupied space.
The depth to which the point of compliance for soil standards developed to protect from ingestion and inhalation from contaminated soil in nonresidential land use settings will be based on an approved risk assessment report.
7. Section 250.407. Remedial investigation report.
Persons electing to remediate a site to the site-specific standard must submit a remedial investigation report to the Department for review and approval. The report must contain the information necessary to define the location, rate, extent and movement of regulated substances at the site and to select appropriate remedial technologies that will be evaluated in the cleanup plan.
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