RISC: Frequently Asked Questions
Table of Contents
General
- Who can answer my questions about RISC sites in my local area? How can I get hold of site managers?
- When are the next set of revisions going to be released for the RISC User's Guide and Technical Guide Manuals?
- The RISC manual mentions RISC software for attenuation modeling. I see nothing on this Web site about it. Is there some software available?
- Is it possible to get either a spreadsheet or database file of RISC default closure levels?
- The technical guide incorporates an out of date U.S. EPA guidance document. Does IDEM request contractors to follow incorporated guidance or newest version?
- Has Indiana adopted RISC (Risk Integrated System of Closure) by rule? Or is it still simply guidance?
Sample Collection/Analysis
- Should soil analytical results be reported on a dry or wet weight basis?
- Are there required/recommended field protocols for sample collection (of soils or groundwater)and/or sample preparation? For example, when collecting a groundwater sample for dissolved metals, should the sample be field-filtered? If there are required protocols, could you provide a reference to them?
- For RCRA unit closure risk assessments, what guidance do you provide to evaluate hot spots?
- Are the industrial default closure levels for metals in groundwater based on "dissolved metal concentrations" from groundwater samples that are filtered to remove suspended solids or are they based on groundwater samples that have not been filtered to remove suspended sediment?
Vapor Intrusion
- What guidance/model does IDEM/RISC use/accept for assessing risk from vapor intrusion?
- Does IDEM recommend indoor air sampling or soil gas sampling for air intrusion issues?
LUST & Excess Liability Trust Fund
- Section 3.1.3 of the LUST Chapter, (Chapter 3), of the User's Guide refers the reader to Appendix 4 for guidance on soil characterization. Shouldn't that reference be to Appendix 4.2?
- What is the relationship between the Excess Liability Trust Fund and the Risk Integrated System of Closure (RISC)?
- What are the necessary steps needed in order to convert a LUST site into a RISC site?
RISC Methodology
- When will toxicity changes be made to a compound?
- Where can I find IDEM's calculation information for direct contact soil-plant-human (residential closure levels) for cadmium in soil. Is there any nondefault site specific soil parameters that can be determined to modify the direct contact closure number?
- How are RISC levels established?
- Are the IDEM RISC numbers and methodology approved by U.S. EPA?
Institutional Controls
- Where would I find guidance in the RISC for institutional controls(i.e., cap/cover) for soils?
- Appendix 5 of the RISC Technical Guide contains examples of environmental notices. The Appendix also discusses how local ordinances may substitute for environmental notices, but there are no examples of local ordinances which IDEM deems acceptable. Do you have any such examples of local ordinances which IDEM deems acceptable as a substitute for the environmental notice?
- For a former industrial property where a Phase II Environmental Assessment indicates that there are no chemical constituents at concentrations above IDEM's RISC default industrial closure levels, where can I find guidance as to what types of uses the property may be used for? Specifically, I am looking to find out if certain types of commercial and retail businesses would be permitted.
TPH
- Is TPH required for screening gasoline contamination? How about weathered gasoline?
- Is IDEM allowing nondefault submittals using TPH fractionation?
Closure
- Can plume stability be used for a plume that extends off-site under a private property or underneath a roadway? If plume stability can be used in either of these cases, are institutional controls or a highway authority agreement needed for the property or roadway prior to closing the incident?
- In addition to a deed restriction, what are the other requirements for closing a site using the industrial criteria?
- There is a groundwater contamination plume of significant length which extends beneath several city blocks. The area is residential, and is served by a city water utility. Does the Responsible Party need to:
- investigate whether there are any water wells being used (potable or for watering gardens/yards). Do they need to conduct a water well survey if there is a city ordinance requiring use of city water utility? Do they need to conduct a water well survey if there IS NOT a city ordinance requiring use of the city water utility?
- record Environmental Notices on the deeds of all the residential properties that are underlain by the contamination plume? Do they need to do the Environmental Notices if there is a city ordinance prohibiting use of private wells and/or requiring use of the city water utility?
- Does a wellhead delineation have to be approved by IDEM before it is considered a Susceptible Area in RISC? What about medium and small community water supply systems that have not yet submitted their proposed wellhead protection areas to IDEM, yet?
- What if a site has completed a commercial/industrial closure and then a wellhead protection area is described that encompasses the site?
- IDEM released a notice in August 2006 announcing that it had changed the default closure levels for several polycyclic aromatic hydrocarbons (PAHs). Does this change work retroactively for these compounds in previous versions of the default closure level tables?
- What is a nondefault closure and where can I find some examples of nondefault closures?
General
1. Who can answer my questions about RISC sites in my local area? How can I get hold of site managers?
RISC is guidance on using a risk-based approach to clean-ups. It will be used by all IDEM remediation programs. The contact should be the program project manager. For more information on remediation programs and active cleanup sites, go to the Remediation Services Branch Web pages.
2. When are the next set of revisions going to be released for the RISC User's Guide and Technical Guide Manuals?
The Technical Guide is currently being revised and the new version will be released in 2008.
3. The RISC manual mentions RISC software for attenuation modeling. I see nothing on this Web site about it. Is there some software available?
The RISC software is being updated, and will be on line again at a later date.
4. Is it possible to get either a spreadsheet or database file of RISC default closure levels?
An Excel spreadsheet containing all the information in Appendix 1 of the Tech guide is available online using the RISC Default Closure Tool in the RISC Toolbox.
5. The technical guide incorporates an out of date U.S. EPA guidance document. Does IDEM request contractors to follow incorporated guidance or newest version?
Use the newest version.
6. Has Indiana adopted RISC (Risk Integrated System of Closure) by rule? Or is it still simply guidance?
RISC is a non-rule Policy Document (NPD) and has not been adopted by rule. However, IC 13-12-3-2 provides that "Sec 2 (a) The remediation and closure goals, objectives and standards for activities conducted under IC 13-22 and IC 13-23 shall be consistent with the remediation objectives set forth in IC 13-25-5-8.5." IC 13-25-5-8.5 basically requires that remediation objectives be risk based.
Sample Collection/Analysis
1. Should soil analytical results be reported on a dry or wet weight basis?
All soil analytical results should be reported on a dry weight basis.
2. Are there required/recommended field protocols for sample collection (of soils or groundwater)and/or sample preparation? For example, when collecting a groundwater sample for dissolved metals, should the sample be field-filtered? If there are required protocols, could you provide a reference to them?
Yes, there are protocols for sample collection and sample preparation. For example, as of May 1, 2007, soils being analyzed for volatile organic compounds (VOCs) may need to be collected by U.S. EPA SW-846 Method 5035A. Please see the IDEM Office of Land Quality document Supplemental Guidance for Sampling Soil and Waste Samples for Volatile Organic Compounds (VOCs) released March 2, 2007 for more information. Sample collection can be program/project specific and IDEM recommends that sample collection, preservation procedures, and analyses be approved by the project manager. Additional guidance is available on IDEM's Geological Services website.
The Sampling and Analysis of Ground Water for Metals at Remediation Sites non-rule policy document (NPD) addresses the filtering questions. "Dissolved metals" typically means that the groundwater sample is field filtered through a 0.45 micron filter. "Total metals" typically means that the groundwater sample is not filtered. Visit the non-rule policy document Sampling and Analysis of Ground Water for Metals at Remediation Sites non-rule policy document (NPD) for more details.
3. For RCRA unit closure risk assessments, what guidance do you provide to evaluate hot spots?
Hot spots can be evaluated by in a number of ways:
- You can establish a simple grid system over the source area and randomly sample within the grid. The results can be averaged using the UCL calculation contained in the RISC guide.
- Another option (for the migration to groundwater pathway) is to calculate weighted averages using multiple sampling intervals within each boring. There are 2 options here:
- divide the vertical column into equal increments, sample each increment and average the results, or
- divide the vertical column into increments based upon stratigraphy, and calculate a weighted average mean for the boring.
See Section 3.4.4 of the Technical Resource Guidance Manual for more information.
4. Are the industrial default closure levels for metals in groundwater based on "dissolved metal concentrations" from groundwater samples that are filtered to remove suspended solids or are they based on groundwater samples that have not been filtered to remove suspended sediment?
They are based upon groundwater ingestion. The analytical procedure for measuring metals in groundwater is program-dependent. Non-rule Policy Document W-0057 specifically addresses the sampling and analysis of groundwater for metals at remediation sites. In summary, sites under the Solid Waste Permits and Hazardous Waste Permits programs utilize filtered samples to provide better statistical data for compliance monitoring. All other programs utilize unfiltered samples with some exceptions as noted in the NPD. Visit the non-rule policy document Sampling and Analysis of Ground Water for Metals at Remediation Sites.
Vapor Intrusion
1. What guidance/model does IDEM/RISC use/accept for assessing risk from vapor intrusion?
General information about Vapor Intrusion and the Vapor Intrusion Pilot Program Guidance can be found at the Vapor Intrusion: Migration of Chemical Vapors In the Soil to Indoor Air Web site. The Vapor Intrusion Pilot Program Guidance is available on the Documents page.
2. Does IDEM recommend indoor air sampling or soil gas sampling for air intrusion issues?
IDEM uses indoor air samples as definitive evidence of indoor air concentrations. To verify that the source is from vapors intruding into the home, subslab soil gas or point of entry samples are necessary.
LUST & Excess Liability Trust Fund
1. Section 3.1.3 of the LUST Chapter, (Chapter 3), of the User's Guide refers the reader to Appendix 4 for guidance on soil characterization. Shouldn't that reference be to Appendix 4.2?
Yes, Appendix 4.2 provides guidance on Default Subsurface Soil Petroleum Characterization for Sites Regulated Under IC 13-11 and 329 IAC 9. The text in Chapter 3 will be corrected at the next printing.
2. What is the relationship between the Excess Liability Trust Fund and the Risk Integrated System of Closure (RISC)?
For a complete answer, see the Excess Liability Trust Fund and RISC fact sheet.
3. What are the necessary steps needed in order to convert a LUST site into a RISC site?
A written notice should be submitted to IDEM. It can be a separate letter or part of the LUST report. There is no specific procedure other than it should be in writing.
RISC Methodology
1. When will toxicity changes be made to a compound?
IDEM uses a hierarchy to establish toxicity values. IDEM will only change its toxicity information if IRIS or Regions 3, 6 & 9 change toxicity values. Even then, IDEM, with certain exceptions, only updates toxicity information every two years. An exception to updates every two years can be made if compounds have significant changes in toxicity values and are also listed consistent with the hierarchy.
2. Where can I find IDEM's calculation information for direct contact soil-plant-human (residential closure levels) for cadmium in soil. Is there any nondefault site specific soil parameters that can be determined to modify the direct contact closure number?
The procedure to calculate the soil uptake to human ingestion pathway is found in Appendix G-1 of U.S. EPA Soil Screening Guidance: Technical Background Document, U.S. EPA/540/R-95/128, May 1996.
3. How are RISC levels established?
Default RISC levels are calculated in order to protect human health and the environment. The target risk level has been set at 1x10-5 risk. Levels are based on default exposure parameters, chemical/physical properties of contaminants, toxicological data, etc. For more detail on the calculation of Default closure values please reference the RISC Technical Guidance document located on the IDEM RISC Web page. The tables in Appendix 1 of the Technical Guidance document contain all the equations and default parameters used.
4. Are the IDEM RISC numbers and methodology approved by U.S. EPA?
No. RISC is state guidance.
Institutional Controls
1. Where would I find guidance in the RISC for institutional controls(i.e., cap/cover) for soils?
Information on Institutional Controls can be found in Appendix 5 of the RISC Technical Guide. Design of engineered controls, such as caps and cover, is something that is the responsibility of the Responsible Party, the Project Manager and their engineering support staff. RISC requires that the institutional controls be memorialized in an Environmental Restrictive Covenant (generic ERC language can be found on the LUST Web site). The Environmental Notice found in Appendix 5 of the RISC Technical Guide is outdated and should not be used. OLC is currently tailoring the generic LUST ERC for each of the program areas. Until that time, the LUST ERC provides a good model to use.
2. Appendix 5 of the RISC Technical Guide contains examples of environmental notices. The Appendix also discusses how local ordinances may substitute for environmental notices, but there are no examples of local ordinances which IDEM deems acceptable. Do you have any such examples of local ordinances which IDEM deems acceptable as a substitute for the environmental notice?
Because local ordinances are unique to each local, the best we can do is to recommend that the ordinance will fulfill the requirements of an EN (and now, an ERC). We do not have any examples of local ordinances that have been used as an institutional control.
3. For a former industrial property where a Phase II Environmental Assessment indicates that there are no chemical constituents at concentrations above IDEM's RISC default industrial closure levels, where can I find guidance as to what types of uses the property may be used for? Specifically, I am looking to find out if certain types of commercial and retail businesses would be permitted.
RISC currently defines land use based upon Standard Industrial Classification (SIC) codes. The SIC codes identify many commercial/retail operations in addition to industrial uses. Land use is defined in section 2.8, and the SIC codes are provided as Appendix 4, in the RISC Technical Resource Guidance Document.
TPH
1. Is TPH required for screening gasoline contamination? How about weathered gasoline?
TPH is required for screening gasoline soil contamination, no distinction is made between fresh and weathered.
2. Is IDEM allowing nondefault submittals using TPH fractionation?
Yes.
Closure
1. Can plume stability be used for a plume that extends off-site under a private property or underneath a roadway? If plume stability can be used in either of these cases, are institutional controls or a highway authority agreement needed for the property or roadway prior to closing the incident?
Plume stability can be used for off site plumes if you have property control through a restrictive covenant or highway authority agreement.
2. In addition to a deed restriction, what are the other requirements for closing a site using the industrial criteria?
There are no special criteria other than the deed restriction (restrictive covenant). Otherwise use the closure criteria in the tech guide.
3. There is a groundwater contamination plume of significant length which extends beneath several city blocks. The area is residential, and is served by a city water utility. Does the Responsible Party need to:
- investigate whether there are any water wells being used (potable or for watering gardens/yards). Do they need to conduct a water well survey if there is a city ordinance requiring use of city water utility? Do they need to conduct a water well survey if there IS NOT a city ordinance requiring use of the city water utility?
- record Environmental Notices on the deeds of all the residential properties that are underlain by the contamination plume? Do they need to do the Environmental Notices if there is a city ordinance prohibiting use of private wells and/or requiring use of the city water utility?
A thorough site investigation is even more important under a risk-based approach. When evaluating contaminated groundwater it is still important to survey the impacted neighborhood for existing or potential well users. We cannot assume that the presence of municipal water means there are no groundwater receptors. You are correct that they need to survey for both potable users and nonpotable users regardless of the existence of a groundwater ordinance.
Restrictive Covenants must be recorded on the deeds of any/all properties where Exposure Prevention remedies are being implemented. For groundwater plumes this includes the properties overlying the plume(s). However, we have identified a process where a municipal ordinance can substitute for Environmental Notice ... check out Appendix 5, section 5.3 for additional information.
4. Does a wellhead delineation have to be approved by IDEM before it is considered a Susceptible Area in RISC? What about medium and small community water supply systems that have not yet submitted their proposed wellhead protection areas to IDEM, yet?
No, a wellhead delineation doesn't have to be approved by IDEM before it is considered a Susceptible Area in RISC. We recommend that parties consult with the local community water supply system about their plans for designating their wellhead protection area and then plan accordingly. If the community water supply has not developed their plan, we recommend that you assume a 3,000 foot radius around the wellhead for your planning purposes.
5. What if a site has completed a commercial/industrial closure and then a wellhead protection area is described that encompasses the site?
If the site has already received its closure document from IDEM, no further action would be required. If the site is in the process of workplan development or remediation, a decision will be made on a case by case basis.
6. IDEM released a notice in August 2006 announcing that it had changed the default closure levels for several polycyclic aromatic hydrocarbons (PAHs). Does this change work retroactively for these compounds in previous versions of the default closure level tables?
Yes. In the case of the nine PAHs referenced in the August 2006 announcement, the ground water closure levels were based on solubility. However, the solubility levels were so low as to make them effectively insoluble. These low solubility levels were sometimes below detection limits that can be readily achieved by laboratories. As such, it was decided that defaulting to the health protective levels for these compounds would be appropriate. Since this is not a change to the health protective levels, but rather a change to policy concerning these select compounds, it was deemed appropriate to allow sites to apply these changes retroactively. This affects the default closure level for ground water and the soil closure level based on migration to ground water. The toxicity data for the nine PAHs listed have not changed since 2001, so the closure levels contained in the table that accompanied the announcement can be applied to any site using the 2001, 2004, or 2006 RISC Default Closure Levels.
7. What is a nondefault closure and where can I find some examples of nondefault closures?"
The term "nondefault" refers to the use of any model, equation, constant, strategy, or process that is not prescribed for general application as a standard within the RISC Technical Guide. Examples of nondefault closures that have been previously accepted by IDEM RISC can be found on the Previously Accepted Nondefault Closures webpage.
If you have questions regarding RISC, please email IDEMRISC at idem.IN.gov.
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