sout 1 8 1988 reply to the attewon of- · concentrations of contaminants observed 1n tar lake...

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UNITED STATES ENVIRONMENTAL PROTECTION AGENCYREGIONS

23° SOUTH DEARBORN ST.CHICAGO, ILLINOIS 60604

REPLY TO THE ATTEWON OF-

1 8 1988CERTIFIED MAILRETURN RECEITT REQUESTED

Mr. James MoranFifty-Sixth Century Antrim

Iron Company Inc .1 Gul f & Western PlazaNew York, New York10023

Dear Mr . Moran :

The U.S. EPA received the "Preliminary Endangerment AssessmentAntrim Iron Works Site" (a.k.a Tar Lake) for review on October 5,1988 and is herein submitting its review comments (enclosed).This Preliminary Endangerment Assessment (PEA) cannot be approved,in whole or in part, because the PEA is deficient with respectto the standards and specifications required by the Tar LakeRI/FS Consent Order.

In summary, the PEA is deficient because it:

Does not adequately address the requirementsof U.S. EPA Endangerment Assessment guidance

Inadequately and incompletely uses the datacollected during the remedial investigation

Does not to provide toxicol ogi cal data forU.S. EPA Hazardous Substance List contaminantsfound in Tar Lake groundwater.

Ambiguously and incorrectly represents theconcentrations of contaminants observed 1nTar Lake groundwater.

The details of these deficiencies are discussed in the enclosedU.S. EPA comments. You will note that U.S. EPA's PEA reviewcomments also include specific instructions for modifying thePEA.

EPA Region 5 Records Ctr.

209151

The U.S. EPA approved schedule for s u b m i s s i o n of the r e v i s e dPEA is forty-five (45) calendar days from the date of t h i sletter. The U.S. EPA expects and requires that the expertisein hazardous waste site i n v e s t i g a t i o n required by Section I ofthe Tar Lake RI/FS Consent Order be immediately a p p l i e d so thatthis schedule can be met.

In the event that the 56th Century Antrim Iron Company, Inc.fails or declines to meet this schedule or submits a deficientrevised PEA, the U.S. EPA may be required to enforce the termsof the Tar Lake RI/FS Consent Order.

Please contact me if you have any questions.

Sincerely,

Peter M i l l e rRemedial Project Manager

End osure

cc: T. Eftaxiadis, MDNRRoger Grimes, U.S.~EP1\ ORCDavid Tripp, Dykema, Gossett et alElisa R i v l i n , G u lf + WesternP h i l Coop, En-Safe

U.S. EPATar Lake Preliminary Endangerment Assessment

Review Comments

The Tar Lake Site (a.k.a. Antrim Iron Works Site) Preliminary Endanger-ment Assessment (PEA) was reviewed by U.S. EPA pursuant to the provisionsof Section II (E) of the Tar Lake RI/FS Consent Order. The provisionfrom Section II (E) is:

" EPA's approval or disapproval [of reports] shall be based on thesubmittal's conformance to the standards and specifications inExhibit A [the RI/FS Work Plan], as it may be amended pursuant tothis Consent Order. In the event of disapproval, EPA shall in-clude a statement of what modifications or additions are required."

The "standards and specifications in Exhibit A" include:

"Endangerment Assessment Guidance" issued November 22, 1985 byJ. Winston Porter, Assistant Administrator, U.S. EPA

The PEA was also reviewed to determine the extent to which it met theobjectives of the RI/FS. The Tar Lake RI/FS objectives (from Exhibit A,the RI/FS Work Plan) that most directly pertain to the PEA are:

- To delineate the areal extent of hazardous substance contami-nation at the site;

- To determine whether groundwater contamination has occuredin the vicinity of the site, the areal extent of such contami-nation; and the impact, if any, on nearby private wells;

To meet RI/FS objectives, the RI/FS Work Plan states that "TheRemedial Investigation will provide technical information regardingthe nature of the contributing waste materials at the site; the flowpaths and impacts of contamination on various media; the flow pathsand impacts if no remedial action is taken; and identify potentialrisks to the public health and welfare and the environmental impactsof various remedial action alternatives."

Finally, the PEA was reviewed to determine the extent to which itaccurately and completely represented site characterization datacollected pursuant to the Tar Lake RI/FS.

The review comments were prepared by excerpting statements from the PEA,and using these as a basis for comment. In the following pages, thePEA excerpt or excerpts are cited, along with their location(s) in thePEA, and this is followed by the U.S. EPA comment.

- Page 1, second paragraph:

" This sequence of studies was made necessary because prior analyticalstudies had failed to establish Tar Lake's impact on ground water otherthan to associate it with possible organoleptic affects in privatedrinking water wells immediately west of Tar Lake."

COMMENT: Prior analytical studies indicated the presence of leadand phenol in Tar Lake groundwater and resulted in TarLake's inclusion on the Superfund National PrioritiesList. The statement would be more correct if it read"This sequence of studies was made necessary because prioranalytical studies had failed to qualitatively or quanti-tatively identify the odorous contaminants in Tar Lakegroundwater." Please revise it accordingly.

- Page 1, third paragraph:

"...this assessment report has been prepared In accordance withthe "Endangerment Assessment Guidance" memorandum prepared onNovember 22, 1985 by J. Winston Porter..."

COMMENT: The PEA does not address the requirements of the Endanger-ment Assessment guidance in that it does not adequatelyidentify and characterize:

a. Hazardous substances and/or hazardous wastespresent in all relevant environmental media(e.g. air, water, soil, sediment, biota);

b. Environmental fate and transport mechanismswithin specified environmental media, such asphysical, chemical and biological degradationprocesses and hydrogeologic evaluations andassessments;

c. Intrinsic toxicological properties or humanhealth standards and criteria of specifiedhazardous substances or hazardous wastes;

d. Exposure pathways and extent of expected orpotential exposure;

e. Populations at risk;

f. Extent of expected harm and the likelihoodof such harm occuring (i.e. risk characteri-zation).

- Page 1, fourth paragraph:

" While full characterization of all ground water contaminants isnot presently possible due to limitations inherent in the scientificprocedure, a list of predicted compounds has been prepared."

COMMENT: The first phrase of this sentence needs to be focusedon results of Tar Lake investigations, as presentpossibilities of other scientific procedures to charac-terize Tar Lake remain to be examined. The firstphrase should instead read " While full characterizationof Tar Lake groundwater contaminants was not achievedwith the the analytical procedures used,".

The "list of predicted compounds" discussed in thesecond phrase presumably refers to the list of "Pre-dicted Alkyl Phenols" that appears in Table 2, page20, of the PEA. This list was based on the resultsof the 10 samples in which the Special Proceduresanalysis revealed an "abundance of identifiablephenols" (RTI, May 9, 1988) Because these 10 samplesalso included other analytes of note, and othergroundwater samples contained contaminants such asnapthalene, benzene, ethylbenzene, and toluene,this list of "Predicted Alkyl Phenols" is incompletefor the purposes of representing possible and actualcontaminants found in Tar Lake groundwater. Additionalcompounds that need to be included in the predictedcompound list are discussed elsewhere in these comments.

- Page 2, first paragraph:

"...the PEA concludes that the extensive expenditure of resourcesnecessary to further evaluate these compounds is not justified inlight of the toxicological data which does exist, the low concen-trations, the limited receptor impact and the age of the site."

COMMENT: Review of Tar Lake RI data and this PEA requiresU.S. EPA conclude that expenditure of resources tofully and properly characterize Tar Lake pursuant tothe National Contingency Plan is still necessary.As noted in these comments, conclusions that the PEAhas drawn are compromised by the limited list ofcompounds for which the PEA provides toxicologicaldata; ambiguous and incorrect constituent concentra-tions which are used to represent the site conditions;and the PEA's neglect of both air inhalation anddirect contact receptor impacts.

- Page 2, Section 0, top of page:

"These compounds are present at levels below 1 ppb."

- Page 15, Section 2.0, first paragraph:

" The colorimetric tests, although considered as screening testsonly, had shown phenolic concentrations ranging from 3 ppb ingroundwater to 64 ppb."


" Table 1 provides a summary of the approximate concentrations ofthe various alky! species. For purposes of the PreliminaryEndangerment Assessment, a concentration of 0.5 ppb [partsper billion] was used for the Health Assessments as this isthe approximate concentration of the most common species."

- Page 29, Section 3.2, second paragraph:

" Therefore it is assumed that for purposes of the PEA, the AntrimIron Works Site is the source of groundwater complaints in thisarea and that the source of these complaints is alkyl phenols atconcentrations below 1 ppb."

Page 35, Section 6.0, third paragraph:

" The highest reported values for alkyl phenols is 0.5 ppb percompound. Typical concentrations are in the range of 0.05 to0.3 ppb."

COMMENT: This series of excerpts pertain to the PEA's represen-tation of organic constituent concentrations in Tar Lakegroundwater. As they appear in Sections 0, 2.2, 3.2,and 6.0 of the PEA, these statements could be mis-interpreted by reviewers of the PEA who are not familiarwith Tar Lake RI data. RI data indicate that Tar Lakegroundwater contains a mixture of alkyl phenols andother organic and inorganic constituents, with totalphenolic concentrations in any given offsite samplemore on the order of 100 ppb than 1 ppb, as indicatedby field screening results. In the revised PEA, therecan be no ambiguity about individual versus total con-centrations of contaminants in Tar Lake ground watersamples.

- Page 2, Section 0, top of page:

"These compounds are present at levels below 1 ppb."


" Table 1 provides a summary of the approximate concentrations ofthe various alkyl species. For purposes of the PreliminaryEndangerment Assessment, a concentration of 0.5 ppb [partsper billion] was used for the Health Assessments as this isthe approximate concentration of the most common species."


" Therefore it is assumed that for purposes of the PEA, the AntrimIron Works Site is the source of groundwater complaints in thisarea and that the source of these complaints is alkyl phenols atconcentrations below 1 ppb."

Page 35, Section 6.0, third paragraph:

" The highest reported values for alkyl phenols is 0.5 ppb percompound. Typical concentrations are in the range of 0.05 to0.3 ppb."

Page 35, Section 6.0, fourth paragraph:

" Based on available data it is concluded that they [compounds] poseno endangerment at the concentrations exhibited in Tar Lake ground-water."

Appendix 1

" Toxicological Data and Health Assessments for Antrim Iron WorksSite"

COMMENT: These five excerpts and review of Appendix 1 indicate thatthe that the PEA has chosen to use the concentrations ofindividual, rather than total, alkyl phenols to estimatehealth risks associated with ingestion of Tar Lake ground-water, and that the PEA makes no attempt to sum up thetotal health risk of all the individual contaminants.Since any given sample of Tar Lake groundwater containsmultiple alkyl phenols and other organic contaminants, thePEA needs address health risks associated with ingestionand exposure to the mixture of all these organic contami-nants. The PEA also needs to evaluate health risks associ-ated with ingestion of and exposure to the benzene, ethyl-benzene, toluene, xylenes, napthalene and tentatively identi'fied compounds revealed by Tar Lake RI data.

- Page 5, second paragraph:

"Tar Lake appears to have shrunk by more than 50% since the 1930'saccording to an evaluation of aerial photographs."

COMMENT: The exact means of deriving this 50% figure needs to beshown, as does the fate of the now apparently non-existentportion of Tar Lake. This sort of analysis may have someuse in determining the rate at which Tar Lake is volatili-zing into the air and migrating into the groundwater.

- Page 5, third paragraph:

"The 56th Co. has not utilized the site."

COMMENT: The statement is meaningless. It would be mean moreif it read " Gulf + Western owned the site until 1985,and then sold it to the 56th Co". Please revise itaccordingly.

- Page 6, top of page

"Local residents indicate that only a few homes continue to usegroundwater."

COMMENT: Precise information on these "few homes", includingwell locations, number of users, water usages andother information to properly evaluate receptorimpacts should be prominently mentioned in the PEA.

- Page 11, paragraph 2:

" If Tar Lake does contain still bottoms, the original constituentsshould be phenolic aldehydes, ethers, and diols."

COMMENT: This list is incomplete without inclusion of other constitu-ents associated with wood tar (i.e. polynuclear aromatichydrocarbons). RI data, scientific literature and data fromtwo similar Superfund sites (Westline, PA, and Cliffs-Dow, MI)indicate that Tar Lake contains a more extensive list of con-stituents than that presented in this PEA. Data from theremedial investigations at these other two sites have beenprovided to your consultant in a separate transmittal.

- Page 13, Section 1.3

" 1988- Ground water samples from monitoring wells and privatewells were taken as a part of the RI/FS. Analysis con-firms presence of alkyl phenols at levels below 1 ppbper compound."

COMMENT: The second statement is incorrect. RI data indicatesconcentrations of alkyl phenols up to 59 ppb and otherorganic contaminants in groundwater at concentrationswell over 1 ppb.

- Page 15, Section 2.1

" Table 2 is a summary of the results obtained."

COMMENT: Table 2 is list of predicted compounds, and not a summaryof Special Procedures analytical results. A comprehensivesummary of the Special Procedures analytical results needsto appear in the revised PEA. Please be sure to includethe results from all Special Procedures samples.

- Pages 17 and 18, Table 1

"Tar Lake Alkyl Phenols"

COMMENT: This tabulation of data is incomplete without addi-tional explanation and qualification. The additionalexplanation and qualification should be in the formof footnotes to explain that the table is based on alimited number of samples and that there were otherorganic constituents, in addition to alkyl phenols,found in those and other samples. In addition, pleaseuse the tentatively identified phenolic compoundsfound in the CLP organic data for any list of "TarLake Alkyl Phenols" that appears in the revised PEA.

- Page 19, paragraph 2

"A list of predicted compounds was then prepared using CRC Handbookof Chemistry and Physics, 68th edition, 1987, CRC Press, Boca Raton,FL. to obtain lists of known compounds meeting the criteria ofC2 through C12 alkyl phenols."

COMMENT: Tar Lake RI data indicate the presence of alkyl phenolsnot shown in Table 2. The CRC Handbook may thereforenot be the best reference for researching predictedalkyl phenols associated with Tar Lake.

- Page 19, fourth paragraph:

" Volat i le analyses were negative for chemical species except forone well which showed positive values at less than 10 ppb for ben-zene and toluene . This same well showed an estimated positivevalue for napthalene. This combination of compounds appears tobe the result of gasoline contamination of the well or the sample.Since these compounds [benzene, toluene, napthalene] do not appearin other wells they are not further addressed in the preliminaryendangerment assessment."

COMMENT: RI data show estimated positive values for napthalenein three monitor wells, estimated positive valuesfor benzene in two monitor wells, an estimated positivevalue for toluene in one monitor well, fully quantifiedvalues for ethylbenzene in two monitor wells, and afully quantified value for total xylenes in one monitorwell. Given the limited number (8) of monitor wellssampled for U.S. EPA Hazardous Substance List volatileand semivolatile compounds , and the presence of thesecompounds in three wells downgradient from Tar Lake,the U.S. EPA must conclude that the PEA has incorrectlydismissed the significance of the presence of theseconstituents in Tar Lake groundwater.

- Page 20, Table 2

"Predicted Alkyl Phenols"

COMMENT: To properly support conclusions about Tar Lake substancesof concern for all relevant media, this table needs to berevised to include aromatic hydrocarbons, polynuclear aro-matic hydrocarbons and other constituents of wood tar. Ifpreferred, a second table titled "Predicted Compound List"may be prepared. Any list of predicted alkyl phenols thatappears in the revised PEA will need to include the tenta-tively identified alkyl phenols found in the CLP organicsanalyses performed during the Tar Lake RI. Any list ofpredicted compounds that appears in the revised PEA willneed to include other compounds tentatively identifiedin the Tar Lake RI data (all three matches).


" The semivolatiles analyses were generally negative except formonitoring wells six and seven which were positive for 2,4-di-methylphenol at 57 and 59 ppb respectively. Quality assurancereviews indicate that these reported data represent multiplealkyl phenols rather than the single species 2,4-dimethyl phenolhowever."

COMMENT: Review of Tar Lake RI data indicates that these con-taminants are present at the stated concentrations,and that other alkyl phenols are present in thesesame samples. Note that Tar Lake RI data indicatesubstantially different retention times for 2,4-di-methyl phenol and the other tentatively identifiedalkyl phenols found in these samples.


" Metals data, summarized in Table 6, are generally represen-tative of the localized groundwater conditions of Antrim County."

COMMENT: Data provided in the PEA are insufficient to substantiatethe statement. The revised PEA should include additionalbackground metals data for comparison with Tar Lake RIdata.


" Although lead has been reported in association with Tar Lake,the data do not confirm this association. Therefore lead hasnot been addressed in the PEA."

COMMENT: The presence of lead in what was considered an up-gradient well, and the limited amount of groundwaterand other data available for the Tar Lake do not providean adequate basis for dismissing lead as a constituentassociated with Tar Lake.

10

Page 22, top of page:

" In summary, the Tar Lake sustances of concern are alkyl phenols,principally C2 and C3 alkyl phenols."

COMMENT: Tar Lake RI data, scientific literature, and RIdata from similar sites causes U.S. EPA to concludethat Tar Lake substances of concern are not limitedto C2 and C3 alkyl phenols. The statement shouldinstead read " In summary, the Tar Lake substancesof concern include aromatic hydrocarbons, polynucleararomatic hydrocarbons, alkyl phenols and other sub-stances associated with wood tar wastes." Pleaserevise it accordingly.

Page 22, Section 2.2, first paragraph:

" Table 1 provides a summary of the approximate concentrations ofthe various alkyl species."

COMMENT: Concentrations of substances that appear in Tables 3and 4 must also be discussed in this section.

- Page 22, Section 2.3:

" A complete description of the analytical methodology used and thefield and laboratory quality assurance may be found in the QualityAssurance Project Plan for the Antrim Iron Works Site."

COMMENT: The statement should read " A complete descriptionof the analytical methodology used and the fieldand laboratory quality assurance criteria may befound in the Quality Assurance Project Plan for theAntrim Iron Works Site." The extent to which datacollected met these criteria should also be discussedin this Section. Any RI/FS data quality problems needto be prominently mentioned.

11

- Page 23, Table 3

" Volatile Organics Analyses - Tar Lake Ground Water"

COMMENT: RI data indicate that the concentrations of ethyl benzeneand total xylenes that appear in monitor well 6 werefully quantifiable. Please delete the "D" data quali-fiers for these contaminants.


" Relevant data for the alkyl phenols in environmental settingsis generally not available from scientific literature. Adsorp-tion coefficients, photodegradation rates, decomposition rates,and transformations in environmental media are not available formost of the compounds. Nevertheless considerable evidence existsthat the still bottoms which comprise Tar Lake are undergoingdegradation; as the volume and area of the Lake have decreaseddramatically in size since AIWC operations on the site ceased."

COMMENT: The revised PEA will need a full bibliographyof the scientific literature used to supportthe PEA's conclusions. Relevant data for all thecompounds associated with Tar Lake (includingaromatic and polynuclear aromatic hydrocarbons) inenvironmental settings need to be examined toaddress the requirements or the EndangermentAssessment guidance. In addition, the U.S. EPA isnot aware of the "considerable evidence" regardingthe degradation of Tar Lake sludges.


" Table 7 contains a summary of data available for these compounds."

COMMENT: Table 7 will need to address all Tar Lake substancesof concern in the revised PEA.

12


" All residents within this area have minimized their exposure tothese compounds by obtaining alternate drinking water supplies."

COMMENT: This statement needs more substantiation. It isU.S. EPA's understanding that some residents inthe affected area continue to draw water from theTar Lake contaminant plume.


" A review of analytical data obtained for the Antrim Iron WorksSite results in a conclusion that the substances associated withthe site are alkyl substituted phenols."

COMMENT: The U.S. EPA only partially agrees. Tar Lake RIand other data require U.S. EPA to conclude thata more extensive list of substances are associatedwith Tar Lake. The statement should instead read"A review of analytical data obtained for theTar Lake Site RI results in a conclusion the thesubstances associated with the Tar Lake groundwaterinclude alkyl substitued phenols, aromatic hydro-carbons, polynuc-lear aromatic-hydrocarbons, andother contaminants associated with wood tar wastes."


" These compounds exist in groundwater on and off site."

COMMENT: This statement should include all the matrices whereTar Lake constituents are found, including Tar Lakeitself, subsoils under Tar Lake, and the air surroun-ding Tar Lake.

Page 35, Section 6.0, second paragraph:

" The only migration pathway is via groundwater"

COMMENT: This statement indicates that the PEA has chosento ignore the significance of air migration ofTar Lake contaminants.

13


" The population at risk are users of the affected aquifer westof Tar Lake."

COMMENT: In addition to ground water users, Tar Lake presentshealth risks for direct contact and via air inhalationfor both humans and biota.

- Page 35, Section 6.0, paragraph 4

" There are substantial data gaps in the toxicological literaturefor these compounds."

COMMENT: A more comprehensive list of predicted compounds associatedwith Tar Lake, one that includes aromatic hydrocarbons,polynuclear aromatic hydrocarbons, and compounds tenta-tively identified in Tar Lake RI data will reduce thesignificance of "data gaps" in toxicological literatureavailable for alkyl substituted phenols.


-"-None of the compounds has been found be- carcinogenic -or terato-genic."

Page 35, Section 6.0, paragraph 4

" However the compounds are not suspected carcinogens or teratogens."

COMMENT: The "compounds" to which the PEA refers in these twostatements are limited to the "Predicted Alkyl Phenols"which the PEA uses to characterize the site. Otherorganic compounds associated with Tar Lake, includingthe benzene and napthalene observed in the Tar Lakegroundwater and those which are likely to comprisethe Tar Lake sludges, are carcinogenic.

14


" The toxicity of direct contact exposure has not been assessed. Itis concluded however based on skin irritation properties of thecompounds that there is a risk associated with direct contact."

COMMENT: Direct contact and air inhalation exposure routes needto be adressed.in the revised PEA.

In summary, these comments indicate that the PEA is deficient with respectto the criteria against which it was reviewed, and therefore cannot beapproved by U.S. EPA in whole or in part.

Before the PEA can be approved, it must adequately characterize Tar Lakein accordance with U.S. EPA Endangerment Assessment Guidance requirements.So that the 56th Co. understands U.S. EPA's requirements for the modifiedPEA, specific instructions for addressing each of the criteria in theEndangerment Assessment Guidance are herein provided:

a. Hazardous substances and/or hazardous wastes present in all relevantenvironmental media (e.g. air, water, soil, sediment, biota);

Tar Lake RI data, scientific literature and data from similarSuperfund-sites shall be used to develop a comprehensive-predictedcompound list of hazardous substances, pollutants, and contami-nants likely to be found in Tar Lake sludges. The compounds andclasses of compounds in the comprehensive predicted compound listshall include at a minimum phenols, aromatic hydrocarbons, andpolynuclear aromatic hydrocarbons. Be sure to include the phenols,furans, and substituted benzenes that were tentatively identi-fied in the Tar Lake RI groundwater samples.

Relevant media identified and characterized by the modified PEAshall include groundwater, air, Tar Lake sludge, and the soilsunder Tar Lake.

b. Environmental fate and transport mechanisms within specified environmentalmedia, such as physical, chemical and biological degradation processesand hydrogeologic evaluations and assessments;

Using the aforementioned comprehensive predicted compound listand relevant media, the PEA shall address environmental fate andtransport mechanisms for the predicted compounds in each of therelevant media. To the extent possible, rates of contaminantmigration into the air, through the unsaturated zone, and ingroundwater should be estimated.

15

c. Intrinsic toxicological properties or human health standards andcriteria of specified hazardous substances or hazardous wastes;

The PEA shall identify and characterize the toxicologicalproperties of all compounds and classes of compounds in thecomprehensive predicted compound list.

d. Exposure pathways and extent of expected or potential exposure;

The PEA shall characterize exposure to contaminated air,contaminated groundwater, and direct contact.

e. Populations at risk;

The PEA shall precisely quantify populations affected and po-tentially affected by Tar Lake groundwater, Tar Lake air, anddirect contact with Tar Lake.

f. Extent of expected harm and the likelihood of such harm occuring(i.e. risk characterization).

Risk characterization shall be performed in accordance withthe procedures in the Superfund Public Health Evaluation Manualand U.S. EPA "Risk Assessment Guidelines of 1986." Both arebeing provided to your consultant in a separate transmittal.

Where available data are found to be inadequate for addressing therequirements of the Endangerment Assessment Guidance, the PEA shall notethe data deficiency so that it can be addressed 1n subsequent Tar Lake RIdata collection activities. This will help ensure the utility of therevised PEA In planning for these additional site characterization studies.

In addition, the modified PEA will need to fully and properly addresseach of the U.S. EPA comments. In Instances where the U.S. EPA com-ment provides alternate language, the U.S. EPA alternate languageshould be used, verbatim, in the revised PEA, wherever the affectedlanguage from the PEA may have appeared.

sout 1 8 1988 reply to the attewon of- · concentrations of contaminants observed 1n tar lake...

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