OSWER Directive9481.00-GC

CHAPTER X POTENTIAL DAMAGE TO WILDLIFE, VEGETATION, AGRICULTURE, AND PHYSICALSTRUCTURES (40 CFR 264.94(b)(1) (viii) and (2) (ix))
In additionto risksto human health, environmental risks must be addressed in

. an ACL demonstration. Unless an ACL demonstration is based on the point of

exposure atthe pointofcompliance, and the nearest likely receptor is human, risks to animals, plants, and structures resulting from exposure to the hazardous constituents must be considered. This environmental risk assessment involves an exposure assessment and an effects assessment. This chapter delineates the information needed to perform the assessments ofrisks otherthan those to human health.
The initialstep in assessing possible environmental impacts isto determine the probable exposure pathways for hazardous constituents to reach environmental receptors. For ACL purposes, the receptors of concern include wildlife and vegetation in aquaticand terrestial environments; agricultural crops, products, and lands; and physical structures. The exposure assessment involves examining the extent of the hazardous contaminant plume, and the location of receptors and environments of concern. The exposure assessment will result in delineation of likely exposure pathways. Information submitted to fulfill requirements discussed in previous chapters should be adequate to determine probable surface water and terrestrial exposure pathways. The permit applicant should examine the data requirements ofChapters VI and VII before proceeding with this chapter. The data for assessing the effects of exposure of physical structures and agricultural crops, lands, and products to the hazardous constituents are discussed in subsequent sections ofthischapter.
The permit applicant must examine the potential impacts to all the receptors discussed above ifexposure to hazardous constituents is likelyto occur. Otherwise, the permit applicant should discuss specific data that supports no probable exposure as well asjustifywhythe potential impactsassessment is unnecessary.

10-1OSWER Directive 9481.00-GC Generally, data on chronic toxicity levels of the hazardous constituents are sufficient to characterize potential environmental impacts. However, chronic environmentaltoxicity data may notbe available for manywaste constituents likely to be the subject of ACL requests. In the absence of environmental toxicity data, ACL applicants may be able to argue that a contaminant will have no adverse environmental effects. This argument could be based upon considerations of exposure levels and thetoxicitiesofsimilar chemical compounds. If environmental receptors are actually being exposed to ACL constituents above chronic toxicity levels, orabove background levels ifno chronictoxicity levels are established, then field assessments of the impacts can be performed to support the proposed ACLs. The types offield studies thatshould be carried out are discussed in more detail in thefollowing sections.
Terrestrial Impact Assessment
The quantification of adverse terrestrial environmental effects is difficult. However, examination ofseveral environmental factors will provide an estimate of potential impacts to the environment due to exposure to contaminated ground water.
Potential impacts to terrestrial wildlife and vegetation can be assessed by examining exposure and environmental toxicity factors. The exposure assessment involves determining whetherthe contaminated ground water at a facility has the potential to impact any terrestrial environment. The specific data necessary to assess the exposure are discussed in Chapters II, Ill, and IV. If there is a likely pathway for wildlife and vegetation to become exposed to contaminants, then environmental toxicity factors should be examined. ACL applicants probably will not need to address terrestrial environmental impacts in detail when there are no direct exposure routes between terrestrial systems and ground water. In these cases, or when the POE is set at the POC, the applicant can omit this section and move on totheendangered speciessection ofthischapter.
The toxicityand bioaccumulation ofhazardousconstituents by terrestrial flora and fauna should be examined if exposure is likely. Terrestrial species can be exposed to toxicants either directly through assimilation of or contact with contaminated ground water, or indirectlythroughfoodweb interactions. Toxicants

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can accumulate in exposed biota and increase to levels that are lethal or have chronic effects. The permit applicant should perform a comprehensive literature search for toxicity and bioaccumulation values for the ACL constituents and their degradation products. The information should be summarized in a table that includes information on thetoxicants,thetestspecies, thespecific effects, the effect levels, the bioaccumulation potential, and the reference. The permitapplicant can base the potential terrestrial toxicity assessment on the most toxic constituent within a group of constituents if appropriate groupings of constituents exist for a facility. If literature information is sparse or non-existent, then a more thorough analysis of potential environmental impacts may be necessary. This analysis could be based on consideration of exposure levels and the toxicities of similar chemical compounds. Bioassays could also be used to supportthe proposed ACLs; however, techniques for performing bioassays on terrestrial ecosystems are not an exact science, and they involve considerable time and expense to carry out. Ifthe permit applicant plans to perform bioassays, he/she should consult U.S. EPA (1984d) for more discussions on the use ofbioassaystocharacterize chemical waste sites.
lfterrestrialenvironmentsare presently being exposed to contaminants above chronic toxicity levels, or above background levels for constituents without established chronic toxicity levels, then field studies can be used to support the proposed ACLs. The permit applicant should examine the dominant terrestrial habitats in thevicinity ofthefacility. Evidence ofany stressed vegetation should be documented and can be supported with aerial infrared photography or ground photographyand vegetation surveys. Both atopographic map and low level aerial photographsdelineatinganystressed terrestrial environmentsshould be submitted. Vegetation survey data on species and abundance of macrofloral plants, usually treesand shrubs, should be collected. However, ifthedominant habitat is an alpine or prairie environment, grasses and other plants should be examined. The community floral diversity can be calculated from the species information. Discussions of diversity should include species richness and community structure. This diversity information should be summarized in tabular form. Any differences between the background and affected habitatsshould be explained. The selection of the background habitat should be carefully planned so as to ensure that it is outside the influence of the facility. Sampling protocols for diversity and productivity studies along with the data collected and a complete discussion of resultsshould be submitted bythe applicant.

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Endangered Species ImpactAssessment Endangered and threatened species nearthe facilityshould be identified. The facility owner or operatorshould contact the U.S. Department of the Interior, Fish and Wildlife Service, for a current list of endangered or threatened species in the vicinity ofthefacility. Ifany endangered orthreatened species are in the area, then the potential impacts ofthe contaminated ground water on the species, including critical habitat impacts, should be discussed. A table should be submitted that lists theendangered andthreatenedspecies. AquaticImpactAssessment
The permitapplicantshould assess potential aquatic environmental effects by examining exposure factors. The exposure assessment for surface waters was discussed in Chapters VI and VII. Ground-water contaminants, flow direction, discharge areas, and proximity ofsurface waters are important considerations. The permitapplicant should examine potential pathways of contaminant migration to surface waters. If exposure to contaminants is likely, then aquatic toxicity factors should be examined. The OfficeofWater, U.S. EPA, has published adocumentthat the applicant and reviewer should find useful in evaluating aquatic impacts (U.S. EPA, 1985a). Ifno hazardous constituents can reach surface waters,thenthe permit applicant should provide supporting evidence of this fact. The aquatic impact assessment can be omitted ifsufficientevidence is availabletosupport aclaim of no surfacewaterexposure. ACLs may be established based on contaminant discharge into asurface water body. This is allowable onlywherethe contaminant plume has already reached the surface water body and the constituents do not cause a statistically significant increase in contaminant levelsover background in thesurface waterconcentrations. That is, after accounting for the inherent variation in the sampling and analysis data, the release of a constituent into a surface water body should not cause an increase inthe background surface waterconcentration ofthatconstituent.
In order to make this determination of statistical significance, samples of surface water should be taken during a period in which the flow (for rivers and

10-4OSWER Directive9481.00-6C streams) orstanding volume {for pondsand lakes) ofthewater body is nearaverage conditions for the specific season. It may also be necessary to collect sediment samples to make this determination. The permit applicant should determine the flow of the surface water at or near the time of sampling and supply this determination, the actual monitoring data, and historical information that demonstratesthattheflowatthetime ofsampling was neartheseasonal average. Surface water samples should be collected within the discharge zone of the ground- watercontaminant plume. The discharge zone will have to be determined on asite-specific basis, and is dependenton the local hydrogeology. Since groundwater movement near surface water bodies can be quite complex, some of the initial samples may have to be collected adjacent to the facility as well as some distance downstream in orderto identifythe discharge zone. If, upon sampling in the discharge zone, the levels of the constituent of concern are not detectable, a statistical comparison ofsampling data does notneed to be performed. However, if the discharge levels are detectable, an appropriate statistical procedure should be used to compare the constituent concentration in the discharge zone to the constituentconcentration upstream in the surface water body. The Agency expects to developfurtherguidance on appropriate statistical techniques for making these comparisons. The background concentrationshould be determined bysamplingthe surface water body in an area that is not expected to be affected by the RCRA facility, and is also notnearothersources ofcontamination.
Ifa RCRA facility receives an ACL based uponthe release ofacontaminant into asurfacewaterbody,thefacility's permitshould contain a requirementfor periodic surface water sampling. The sampling frequency should be determined on a sitespecific basis to assure that the constituent concentration does not surpass a statisticallysignificant level over background in thatsurface water body.
If it is found thatthe ground-water contamination discharge is not causing a statisticallysignificant increase over background in the surface water body, then an ACL for an operating unit may be set at the contaminant levels currently at the point of compliance. However, ifthe ground-water contaminant plume contains much higher levels ofcontamination {i.e., hotspots) than have already reached the surface water,these hotspots may haveto undergosome form ofcorrective action, so as to not violate the standard of statistical significance. To meet this standard,

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appropriate ground-water contaminant plume management techniques will have to be selected on asite-specific basis. Agricultural ImpactAssessment
The potential impacts of ground-water contamination on agriculture should be examinedwhenthe POE is notset atthe POC. Exposure pathways, crop impacts, and livestock impacts should be included in the assessment. The exposure assessment is used to determine if there are likely pathways for ground-water contaminants to reach any agricultural lands or products. As part of the exposure assessment, data on the agricultural land uses nearthe facility should be submitted by the permit applicant. Specific uses such as row crops, rangeland, grazing, tree farming, and timber should be depicted on an appropriately scaled map. A table that lists acreages ofthespecific uses should also be submitted.
The potential exposure pathways that the permit applicant should examine include shallow ground water, ground-water irrigation, and surface water irrigation. The shallow ground-water flow direction, aquifer attentuation mechanisms, and ground- water elevation are important characteristics that are used to determine exposure due to direct crop uptake of ground water. These topics were discussed in Chapters Ill and IV and must be evaluated by the permit applicant during this exposure assessment. The irrigation wells near the facility should be identified and delineated on a map employing the appropriate scale. Chapter VII lists specific use information that is necessary for this assessment of the irrigation wells. Surface waters that are used for irrigation and have the potential to be impacted by ground-watercontamination must be evaluated (see ChapterVI). The current and projected irrigation withdrawal rates should be determined from each irrigationsource. Agricultural crop impacts should be assessed by the permit applicant if exposure toACL constituents is likelyto occur. The following potential agricultural impactsshould be assessed:
1. Direct crop impacts and reduced productivity, and 2. Bioaccumulation ofcontaminants.



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The permit applicant may be able to estimate the expected crop and productivity impacts resulting from exposure to hazardous contaminants in the ground water by examining the literature. Literature values that exist on crop impacts from exposure to the contaminants should be summarized in a table that includes the contaminant, the crop tested, the effect level, the bioaccumulation potential, and the specific reference. The U.S. Department of Agriculture (USDA) can be a source of crop effects information and testing methods. If literature information does not exist and crops are likely to be exposed to ACL constituents, theACL demonstration may be denied and the ground-waterstandards may be set at background levels. However, the permit applicant has the opportunity to carry outexperimentsto estimate potential crop impacts. The applicantshould be aware thatstandard experimental protocols do not exist and that all data to support the ACL demonstration must be submitted in atimelyfashion. Iftests are performed by the permitapplicant, all protocolsand datashould be submitted.
The permit applicant should describe potential livestock impacts that may occurfromdirectand indirectexposure tocontaminantsfound in thegroundwater. Direct exposure would include livestock contact through watering. Indirect exposure could include contactduring animal grazing and foraging. The applicant should submit any available information on potential livestock impacts ofthe ACL contaminants. If literature values exist, the information should be summarized in tabular form and include the factors discussed above in the crop impacts section. The USDA may have information on this topic. Permit applicants are not normally expected to carry out experiments on exposed livestock because of the high costs and long-term nature of such experiments. If exposure modeling shows that livestock exposure occurs and sufficient literature information does not exist to supportan ACL, then the concentration limitmay be setatbackground levels. Physical Structure ImpactAssessment Physical strucures can be adversely affected by hazardous constituents in the groundwater. The situation at Love Canal, NY, wheretoxicants entered basements of homes, is just one example. The determination of potential damage to physical structures in the area around the facility requires the examination of exposure pathways, waste characteristics, environmental factors, and construction materials andtechniques.



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Determining the potential exposure of the physical structures to waste contaminants requires identification of physical structures in the area and exposure pathways. All manmade structures including buildings, buried cables and pipes, railroad beds, roads, parking areas, and machinery near the facility should be identified and delineated on a vicinity map if they are likely to be reached by contaminants. The possible exposure pathways ofthe ground-water contaminants tothe physical structures should be identified. The permitapplicantshould referto Chapter IV to determine what information should be submitted in order to determine contaminant migration pathways. If the exposure assessment determines that physical structures are likely to come in contact with ACL contaminants, then the potential effects of the contaminants on the physical structures should be examined. Otherwise, the permit applicant needs only to explain whythe assessment is not needed.
The hazardous constituent characteristics of primary concern for the physical structure impact assessment are reactivity, ignitability, and migration potential. Two important categories of reactive chemicals are corrosives and solvents. The ground-watercontaminantsthatfall into either ofthese two categories should be listed in atable by the permitapplicant. The potential effects ofthese compounds on building materials such as concrete, iron, steel, plastic, wood, asphalt, and limerock should be identified and summarized in a table. The ability of the contaminants to permeate these materials should also be discussed. The permit applicant should submit data on the flammability and ignitability of the ACL constituents that have the potential to permeate subsurface structures. Volatile organic compounds should be given special attention since they have been implicated in sewer-lineexplosions.

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CHAPTER XI
PERSISTENCE AND PERMANENCE OF POTENTIALADVERSE EFFECTS (40 CFR 264.94(b)(1)(ix) and (2)(x))

Many ofthe chapters in this guidance document discuss informational needs for ACL demonstrationsthat are related to the persistence and permanence ofthe ACL constituents. The general ACL policywill be to assume aworstcase approach of no degradation of the ACL constituents, unless information on the persistence of theACL constituents in the environment is submitted. Similarly, ifa potential exists for exposure tothe ACL constituentsto result in adverse effects,the adverse effects will be considered permanent unless they are generally accepted to be not permanent or information is submitted by the permit applicantto justify thatthey are not permanent. This chapter describes the information that is needed to characterize the persistence of the ACL constituents in the environment and the permanence oftheiradverse effects ifexposure occurs. Persistence
Information on the persistence ofthe contaminants in theenvironmentshould be discussed in varying detail, depending on the basis of the ACL demonstration. The applicantshould discussthe process by which each ACL constituentwill degrade ifthe demonstration is attenuation-based. The processes should be discussed from aground-waterperspective, asurfacewaterperspective, orany otherenvironments or combination of environments depending on the site-specific situation. Contaminant degradation in ground water occurs predominantly through chemically mediated processes. Ifthe applicant is claiming attenuation as a means ofreducing the contaminantconcentrations,the applicant mustdiscussthetypes of processes that may occur. These processes can include biodegradation, hydrolysis, photolysis, oxidation, reduction, adsorption, dispersion, or precipitation, all of which were discussed in Chapter II. The various degradation products, if known, should also be discussed.

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Ifsurface waterexposure is involved, bioconcentration and biotransformation processes are important. Bioconcentration factors are important for evaluating human intake levels of contaminants from consumption of aquatic organisms and forassessing the permanence ofecological effects. Bioconcentration factors can be derived by experimentation or calculation or are provided in the literature. The applicant should provide justification for the use of any bioconcentration factors. Biotransformation is primarily carried out by microorganisms in the surrounding media. A lag time or acclimation period usually occurs before the biodegradation process begins. If biotransformation is used in the ACL demonstration, the applicant should determine whether the microbes are acclimated to the contaminant. A discussion of biotransformation and the use of bioconcentration factorscan be found in U.S. EPA (1980) and U.S. EPA (1979).
Ifdegradation processes are used in the ACL demonstration, the process rates should be calculated. Whether the mechanism of degradation is biological or chemical, all rates describing the processes should be included in the ACL demonstration. The parameters, coefficients, and assumptions used by the permit applicant to calculate the degradation rates for each contaminant should be submitted in tabularform.
Permanence
Information on the permanence ofthe adverse effects resulting from exposure totheACL constituentswill be required only ifthe ACL demonstration is based on attenuation mechanisms. This information should be included in the demonstration's health risk assessment (Chapter IX) and the environmental risk assessment (Chapter X). Permanence information is necessary in order to give the permit reviewer some idea of the long-term effects associated with exposure to each ACL constituent as well as a better understanding of which ground-water contaminants are ofmost concern. Many environmental systems exhibit a high degree of resiliency. If the damage is limitedto individual organisms within the population and the gene pool is not irreparably depleted, the environmental damage may be reversible. However, ifirretrievable habitatchange has occurred, then environmental damage may be permanent. The permit applicant should examine the literature on the

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contaminant's environmental effects to determine the permanence of likely ecological impacts. Many biological evaluations can be performed to examine the resiliency and stability of an environmental system. Some examples include tissue analyses to determine bioaccumulation, diversity and recovery studies to estimate elasticity, and intolerant species analyses to determine the degree of degradation. A detailed explanation of these studies is presented in the Technical Support Manual: Waterbody Surveys and Assessments for Conducting Use Attainability Analyses (U.S. EPA, 1983d). The permanence ofthe adverse effects is related to the contaminant's concentration level atthe pointofexposure. The acute and chronic effects levels foreach contaminantshould be determined ifthe ACL demonstration is based on attenuation considerations. The effects should be classified as either reversible orirreversible.

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CHAPTER XII
SUMMARYAND CONCLUSIONS

The factors involved in preparing and supporting an ACL demonstration were discussed in the previouschapters. Chapter IoutlinedtheAgency's policy quidelines for implementation of the ACL process. Information on each of the criteria discussed in this guidance document is not required in every ACL demonstration because every RCRA facility is unique with different environmental properties and waste characteristics. Therefore, each ACL demonstration based on attenuation mechanisms must reflect site-specific conditions. Much ofthe information required foran ACLdemonstration may be taken from the facility's Part Bpermitapplication. This guidance document points out when additional information that satisfies the criteria should be submitted and also when it may not be necessary. However, the burden is always on the permit applicant to justify all arguments used for not submitting information on specific criteria. Appendix Bcontains a list oftables and figures that can be submitted as part of an ACL demonstration. The use of these tablesand figureswill greatlyfacilitatethe review oftheACL demonstration by the permitwriters. Appendix Balso containsasummary outlineofthe information that can be used tosupportan ACL demonstration. The permitapplicantshould be sure to submit all data necessary to fulfill the information requirements outlined in this Appendix.
Once thedata have been submitted by the permit applicant, the permitwriter must assess the quality ofthe submitted information and determine the allowable concentrations ofcontaminants atthe pointofexposure, and theACLs atthe point of compliance. In many cases, the permit writer will have to use professional judgementin determiningtheadequacyofthesubmitted information.
The Agency will indicate its decision on the merits ofthe ACL demonstration when it issues the permit. The permit will contain a ground-water protection standard {GWPS) foreach ground-watercontaminant. The GWPSwill contain either background values or the National Interim Primary Drinking Water Regulation limits listed in Table IofSection 264.94{a) {if EPA rejects the ACL demonstration), or

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it will contain ACLs. If any constituent exceeds its ACL, corrective action will be necessary. The ACL then becomes the benchmark for the intensity and duration of thecorrective action.
As partofthe ground-waterprotection standard, an ACL is in effectduring the compliance period. The compliance period is the number of years equal to the active life ofthe waste management area, including the closure period. If, at the end of the compliance period, the owner or operator is engaged in a corrective action program,the compliance period is extended until the owneroroperator can demonstratethatthe GWPS, which may contain ACLs, has not been exceeded for a period ofthree consecutive years. Once the ground-water protection standard has been set in the permit, the permittee can only seek ACLs through permit modifications under the procedures outlined in 40 CFR Part 124. Such modifications are always major and the burden of proof to justify the variance is on the applicant. If a facility owner or operator violates the ground-water protection standards, he or she cannot postpone corrective action in orderto argue forACL changes.

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CHAPTER XIII REFERENCES

Bouwer, H., 1978. Ground-waterHydrology. McGraw Hill, NewYork, NY. Brady, N.C., 1974. The Nature and Property of Soils. The MacMillan Company, New York, NY. Freeze, A.R. and J.A. Cherry, 1979. Groundwater. Prentice-Hall Inc., Englewood Cliffs, NJ. Kruseman, G.P. and N.A. De Ridder, 1979. Analysis and Evaluation of Pumping Test Data. International Institute for Land Reclamation and Improvement Bulletin 11, Wageningen,The Netherlands. Ruffner,J.A., 1980. Climatesofthe States. Gale Research Company, Detroit, MI. Ruffner, J.A. and F.E. Blair, 1981. The Weather Almanac. Gale Research Company, Detriot, MI. Todd, D.K., 1980. Ground-water Hydrology.2nd Ed., John Wileyand Sons, Inc., New York, NY.
U.S. Environmental Protection Agency, 1979. Water-Related Environmental Fate of 129 Priority PollutantsVolumes Iand II. EPA-440/4-79-029a and b,Washington, D.C. U.S. Environmental Protection Agency, 1980.WaterQualityCriteria Documents; Availability. Federal Register45:79318-79357, November28, 1980. U.S. Environmental Protection Agency, 1982a. Subpart F-Ground-water Protection. Federal Register47:32350-32356,July 26,1982.

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U.S. Environmental Protection Agency, 1983a. Draft RCRA Permit Writers' Manual for Ground-water Protection. Contract No. 68-01-6464, October 4, 1983.
U.S. Environmental Protection Agency, 1983d. Technical Support Manual: Waterbody Surveys and Assessments for Conducting Use Attainability Analyses. OfficeofWater Regulationsand Standards, Washington, D.C., November, 1983.
U.S. Environmental Protection Agency, 1984a. Ground-Water Protection Strategy, OfficeofGround-Water Protection,Washington, D.C. August, 1984.
U.S. Environmental Protection Agency, 1984b. Hazardous Waste Management System; Ground Water Testing and Monitoring Activities; Proposed Rule. Federal Register49: 38786-38809, OctoberI, 1984.

U.S. Environmental Protection Agency, 1984d. Characterization of Chemical Waste Site Contamination and Its Extent Using Bioassays (Draft Report). Contract No. DEAC06-76RLO 1830, December, 1984.
U.S. Environmental ProtectionAgency, 1985a. Technical Support Document for Water Quality-based Toxics Control. Office of Water, Washington, D.C.
U.S. Environmental Protection Agency, 1986a. RCRA Ground-Water Monitoring Technical Enforcement Guidance Document, Washington, D.C., September, 1986.
U.S. Environmental Protection Agency, 1986b. Superfund Public Health Evaluation Manual,Washington, D.C., October, 1986.
U.S. Environmental Protection Agency, 1986c. Final Guidelinesfor Estimating Exposures. Federal Register 51: 34042-34054, September24, 1986. Walton, W.C., 1970. Ground-water Resource Evaluation. McGraw-Hill Publishing Company, NewYork, NY.

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Other resource documents Black, C.A., 1965. MethodsofSoil Analysis. American SocietyofAgronomy, Madison,WI.
U.S. Environmental Protection Agency, 1978.1nvestigationofLandfill Leachate PollutantAttenuation by Soils. EPA 600/2-78-158.
U.S. Environmental Protection Agency, 1980.Adsorption, Movement,and Biological Degradation of Large Concentrations of Selected Pesticides in Soils. EPA 600/2-80-124.
U.S. Environmental Protection Agency, 1982. Handbookfor Remedial Action at Waste Disposal Sites. EPA-625/6-82-006,Washington, D.C., June, 1982.
U.S. Environmental Protection Agency, 1982. Preamble-Section D: Ground-water Protection (Part 264 SubpartF). Federal Register47:32291-32312, July 26, 1982. U.S. Environmental Protection Agency, 1982. Handbookfor Performing Exposure Assessments (Draft). Washington, D.C., November, 1982. U.S. Environmental Protection Agency, 1983. DraftGuidelinesfor Deriving Numerical National Water Quality Criteria for the Protection of Aguatic Life and its Uses. Washington, D.C., July 5, 1983.
U.S. Environmental Protection Agency, 1983. Protocol for Bioassessment of HazardousWaste Sites. EPA-600/2-83-054, July, 1983.
U.S. Environmental Protection Agency, 1983.WaterQualityStandards Handbook, Office of Water Regulations and Standards. Washington, D.C., December, 1983.
U.S. Environmental Protection Agency, 1984. Soil PropertiesClassification and HydraulicConductivityTesting (Draft Report). SW-925.

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