/ •\

SUE-12

fir. William KlettkeVice President, FinanceThe Enterprise Companies1191 S. Wheeling RoadWheeling, I l l i n o i s 60090

Oedr Hr. Klettke:

Re: Midco I, Midco II RI/FS

U.S. ERA has completed Its review of the second draft of the *1idco IRemedial Investigation (31) dated April, 1937. The results of the reviewshow that the Participants have failed to comply with a number of require-ments of the Oecree as well as standard U.S. EPA practices, which are setforth in U.S. EPA guidance documents and soTie of which were corrnunicate<1to the Participants in my letter dated February 13, 1937.

Trie specific U.S. EPA requirements that niust be compiled with to re-ceive U.S. EPA approval of the RI and necessary correctivp measures arelisted in the Attachment to this letter. In addition, the delay in sub-mission of this second draft of the Midco I RI is considered excessive,and tiie second draft of the Midco II RI has still not been submitted nowover tnree months since the Participants received the Agency commentsduring the meeting on January 21, 1937.

Further-lore, the Participants appear to have delayed submission ofthe April 19d7 draft RI until after it was reviewed oy the Midco TechnicalConinittee. This is in violation of Paragraph IX A. of the Decree, whichstates:

Tne Particpants shall direct their contractors tosubnit copies of all documents containing technicalinformation prepared or received by their contractor,including sample analyses, chain of custody records,contracts, b i l l s , receipts, correspondence, reports,and other documents, produced during or as a resultof tne performance of the ^I/FSs, in the monthly re-port immediately following their preparation.

fTherefore, future reports, Including the next drafts of the Midco

I and Midco II RI's, that are prepared by your contractor must be sub-mitted directly to U.S. ERA. Also, please submit copies of all draftreports that your contractors sent to the Midco Trustees before theywere submitted to U.S. ERA.

The Participants should comply with the schedule included 1n thisletter.

The schedule is as follows:

Submit Midco I RI with the correc- 7/31/87tions Identified in this letter

Submit Midco II RI with corrections 45 days fron receiptidentified in this letter and my of this letter,letter dated February 18, 1987

Submit final Midco I RI Includingadditional data 7/31/37

Submit final Midco II RI including 9/9/87additional data

SuDinit Draft Midco I FS 9/15/37

Submit Draft Midco II FS 10/23/87

Submit Final t-tidco I FS 30 days after receiptof U.S. EP4 commentson the Midco I draftFS

Sumbit Final Midco II FS 30 days after receiptof U.S. EPA commentson the Midco II draftFS.

Unless substantial changes are made in the RI, U.S. EPA will be un-able to approve its completion pursuant to Paragraph V of the Oecree.The date for submission of the final Midco I RI was moved up one monthfrom the date proposed in the May 4f 1987 letter from Arthur F. Slesingerbecause the additional data for the Midco 1 RI is minor and should requirelittle tine for incorporation into the final report. The date for thefinal Midco II RI was moved up three weeks because the sampling will becompleted tnree weeks ahead of the date projected in Mr. Slesinger'sletter. The dates for the draft FS's were set at 1 1/2 months after sub-mission of the final RI's because the great majority of the work on tnesereports can be completed during completion of the RI's especially sincethe bulK of the data has been available for these sites for well over sixmonths now.

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If you ne*><* to <11 scuss the require* chanyps in t^e Mcico 1 Ri pleasecall mcMM ?,o1r.p of ry stflff at (312) 0^6-47^0. Thar* you.

Sincerely,

Basil (;. Constantelos, DirectorUaste Mana'-jenent Division

cc: A. Carter, IDEMB. Pten, r.PAR. Ball, EPfK. St.1npson, V.'^stonK. r

ATTACHMENT

LIST CF CHANGES REQUIRED BY U.S. ERA TOTHE APRIL 1987 MIDCO I REMEDIAL INVESTIGATION

Appendix FE, pp E-l, E-2, Section 5, Section 6: C l a s s e s of

compounds can not be arbitrari ly deleted from the data base for

the indicator parameter selection or the risk assessment. U.S.

EPA has established procedures for accepting or rejecting data,

and these have been clearly communicated to Geosciences Research

Assoc ia tes.

Paragraph VC of the Decree states that the Part icipants shal l use

quality assurance, quality control and chain of custody procedures

in accordance with a U.S. EPA approved plan as required in Exhibit

R and C. Exhibi t B requires completion of a Qual i fy Assurance

Project. Plan (OAPP) .

The approved QAPP provides for Geosciences Research Associates to

complete the data assessment function, to initiate corrective action

procedures for unacceptable data, and to notify the U.S. EPA OSC of

data problems that have s igni f icance to the completion of the project.

Therefore, data should not be deleted without fo l lowing th is procedure,

This includes the Phase I cyanide data.

In general there is no just i f iable reason not to include all val idated

data in the risk assessment including inconsistencies between sampling

rounds.

This point of view is made clear on page 21 of the Draft Superfund

Public Health Evaluat ion Manual, which states:

"Concentration values used in this [scoring for site screening]equation for a given chemical should be representative of allava i lab le monitoring data.10

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1°QA/QC val idated monitoring data should be used for select-ing indicator chemicals."

Therefore, all tables, f igures, graphs, assessments and discussions

must be corrected to include thp data that has been improperly deleted.

This includes data and discussions on pages ES-3, ES-4, Sections 5,6,

and 7 and Appendix F.

The QAPP requires that a section or sections of the final RI report

deal with information concerning data quality and procedures. Such

a section must be incorporated into the RI report.

Section 5 and 6: Task 4 of Exhibit B requires that comparisons with

appl icable EPA/State standards or criteria be included. The first

draft did a good job of this by presenting maps that plotted data

above drinking water standards. These included Figures 5-9, b-10,

5-11, 5-13, 5-14, 5-26, 5-27, 5-28, 5-29, 5-32, 5-33, 5-38, 5-39,

5-40, 5-41, 5-44, 5-45. These plots must be incorporated back into

the report in order to faci l i tate data review and comparison to

standards. In addition, maps must be incorporated comparing sur face

water data with ambient water quality criteria for aquatic life.

Section 5: Task 4 of Exhibit B of the Decree states that "The si te

invest igat ion data will be analyzed to fully define contaminant con-

centrat ions in each environmental pathway (both at the source and off-

si te), and the results will be presented graphical ly to depict average

and/or "hot-spot" concentrations of critical indicator parameters."

Some plots included in the first draft RI were very helpful in defining

the extent of contamination but were excluded from the second draft.

These include Figures 5-12, 5-15, 5-16, 5-17, 5-18, 5-19, 5-20, 5-22,

5-23, 5-24, 5-3U, 5-31, 5-34, 5-35, 5-36, and 5-37. These figures should

be incorporated back into the report.

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Executive Summary: This must be rewritten to point out the problems

and not the non-problems. All compounds that we have good evidence for

release to the ground water and sur face water must be listed. Com-

pounds exceeding appl icable standards must be listed. In addition, it

must be modified to take into account changes made in response to re-

qulred changes.

ES-1:

a. Lines 13-14:

This statement is incorrect because there were no Federal regu-lations in effect regarding hazardous waste handling proceduresuntil November 1980. You must also contact the State of Indianain order to find out for sure whether any State hazardous wastehandling regulations were in effect during the time the Midcofacil i ty was in operation. This statement must be corrected orelimi nated.

ES-2:

ES-3:

a

Lines 9-10:

No clay cap is impervious, and the cap installed at Midco I wasnot well constructed to promote drainage. The clay cap does notcover the entire site. Therefore, these statements must be cor-rect pd.

Lines 12-19:

The described purpose of the RI must be made consistent w i th theConsent

The descr ipt ion of the removal action must be corrected to be con-sistent with the desription on page 1-6 to 1-7.

Lines 4-5 { a l s o ES-4, lines 6-8)

M.S. EPA will never approve the report with this statement in itunless it is backed up by a clearly presented, object ive presenta-tion of all site data. As it is the data appears to indicate other-wise. Furthermore, the work "legitimately" has a legal connotationand, therefore, can not be used in an RI report.

Lines 12-13:

The relationship between the high salt and elevated bariumlevels was not proven in this report. Therefore, "have alsobeen" must be changer! to "may a lso be" or an equivalent.

Lines 14-16:

It is not clear what you mean by isolated waste disposallocations" especially since Midco could also have dunpedchemicals off the site proper. Furthermore, the reportfails to prove that cyanides detected are not from the site.Therefore, you can not state without qualifications thatthe cyanide contamination is not from the site. Furthermore,the data in Figure 5-14, strongly suggests that cyanide inthe ground water is from the site.

Lines 16-18:

Identify whether you are referring to ground water or soilsamples.

Lines 20-23 and 1-2 on ES-4:

The report fai led to document that PNA 's are widespreadin the general area. Without such documentation, thisstatement can not be made. Furthermore, you have notproven that no PNA 's were released by Midco I and PNA 'sare elevated on the site; therefore, you can not implythat all PNA 's are from other sources.

Lines 8-10:

I can see no criteria for this list of compounds. Youmust identify whether these are the most abundant, mosttoxic, etc. or insert a comprehensive list of compoundsdetected on site.

Line 11-12:

Change this statement to make it clear that the modelingprovides only a prediction of future contaminant movement

ES-5:

Lines 23-24

Remove the reference to the indicator chemicals sincethese have not been defined in the executive summary.If a statement is made regarding comparison to standards,it must include information for all parameters measured.

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ES-6:

a. Line 3:

It is not U.S. E P A ' s posit ion that its guidelines are overly con-servat ive. Therefore, this statement must be changed to obtainU.S. EPA approval.

b. Lines 6-7:

The word "legitimately" has a legal connotation and, therefore,cannot be used in an RI report.

c. Lines 9-11:

The stated overal l goal of the FS must be restated to be consistentwith that stated in the Consent Decree.

d. Line 13-16:

nptermination of reasonable and unreasonable remedial actions willbe made in t heFS . Therefore, these conclusions can not be statedin the RI report. In addition, all references to responsibi l i t iesfor site related costs must be removed.

Page 2-5:

Change "Except for the December 21, 1982 sampling, the tpto"0nly inthe December 21, 1982 sampling were."

Page 3-6 and 5-2:

The permeability test on the confining layer should have been comp-leted by now.

Page 3-9:

Identify the type or types or dioxin for which the anayls is were con-ducted.

Page 4-9 to 9-11:

Make the modifications suggested in the May 11, 1987 letter from DavidC. Hudak, U.S. Fish and Wildlife service.(attached)

Page 4-22:

The second sentence should be moved tn the end of the paragraph.

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Page 4-27: 5-2:

In paragraph 2, a conservat ive value for the clay 1 tillconf ining bed permeabi 1i ty should he used since fieldpermeability is almost always greater than that measuredin a laboratory.

Page 4-28:

In paragraph 2, change the word "overf low" to "backup."

Page 5-3:

I don't think that the clay cap extended east of Blain St.Figure 3-1 was not included.

Page 5-4:

Add the fol lowing parameters to the l ists of main contami-nants detected in the soil borings: methylene chloride,acetone, methyl ethyl ketone, bis (2-ethyl hexyl) pthalate,2-n-octyl pthalate, and 2-methylnapthalene.

The report fails to prove that semi-volatile compounds werecaused by " isolated disposal or source points." Therefore,the statement "distribution of semi-volat i le compounds in offsite wel ls ...indicate isolated disposal or source points"must be qualified or eliminated.

Page 5-6:

In paragraph 1 under 5-3, the target compounds must be iden-t i f ied. Table 5-4 l ists HNU results, which is OK, but it issupposed to have soil screening results. This must be cor-rected.

In paragraph 2, state that chloroform and methylene chloride/MEK were also frequently detected in high concentrations inthe test pits.

Page 5-7:

Describe the occurarice and concentrations of cyanide in thetest pits.

Page 5-8:

Only stations 3 and 11 should he used for calculating relat ivelynon-site impacted surface water and sediment. Even these loca-tions could be questioned.

You must state the criteria for the selection of substances forbackground evaluation. You must list all the contaminants detec-ted at stations '1,5 and 7 that were not detected at 8 or 11.

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Page 5-9 ( las t sentence):

Clar i fy what is meant by "total number of samples."this the total non-hackground samples?

That is, is

Page 5-10:

In the first draft and later in this report compounds other thanlead were identified as being above drinking water standards.In addition, the surface water data must be compared to the ambientwater quality criteria for aquatic life for each parameter.

Page 5-11:

You have failed to prove that the cyanide can not be related tothe Midco I site. Therefore, you can not state that "cyanide inthe surface water can not be related to the Midco I site," Itis unclear what is meant by "isolated disposal pract ices," itshould be noted that Midco could have used "isolated disposal prac-tices."

Page 5-12:

You must list the compounds detected in the surface sediment at SD-1,SD-4, SD-5, and SD-7 but not in SD-3 or SD-11. You nust compare thelevels of CN detected in SD-1, SD-4, SD-5, and SD-7 to levels inSD-3 and SD-11.

Page 5-13:

Change "Residentialfor 5.5.2.

Page 5-15:

The 20^9/1 value ismust not be used to

Sediment" to "Residential Soil" as the heading

a guideline for person on a low sodium diet andimply that it renders the water undrinkable.

Page 5-16:

El iminate references to the UIC regulation. These are not relevantas explained in our comments on the first draft.

Page 5-17:

You have failed to prove that the heavy metals contamination couldnot have come from the site. Therefore, you can not state that "Nocontamination due to heavy metals which is both attributable to thesite and in excess of ....standards, has been detected beyondwells......"

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Page 5-17 to 5-18:

You have fai led to prove that the cyanide does not form a plumefrom the site. In fact, the Phase I data shows a distinct plume.Furthermore, MW4 and MW7 are not necessarily background wells.Waste disposal could have occurred there or at MWB and C1U ratherthan the middle of the site. Therefore, the variations noted aretr ival. The paragraph on cyanide must be rewritten including con-sideration of the Phase I data.

Page 5-20:

a. Lines 4-6:

Trans-1,2- dichl oroethene detected in residential well IWGS was notattributable to laboratory contamination. Therefore, this state-ment must be corrected.

b. Line 8:

Take out the words "confirmed compound," Either it was detected,or it was not detected. Further qual i f icat ions must be clearly ex-plained, c. The wells used for the background calculation mustbe listed.

d. All compounds detected in on-site and down-gradient wel ls , but notin "background" well must be listed In section 5.6.3. along withcompounds highly elevated compared to background.

e. It is confusing what you mean by "off-site wel ls." Apparently youare not using the same definition here as you used in Appendix FE.Therefore, you must already define what you mean by on-site, andoff-s i te and consistently used this definition. It may be clearerto use the terms on-site, up-gradient and down-gradient.

Section 5:

a. You must comment on the toxic organics detected in well B9U and dis-cuss what i t means.

b. You must evaluate the potential for movement of contaminants throughthe clay confining layer and into the bedrock.

Section 5.6,5:

You must implement the changes in the ground water modeling agreedto in the meetings on 5/29/87 between ERM personnel, and Rich Roiceand Weston personnel. The changes agreed to include:

You will attempt to use a realistic constant fluxor constant head boundary of the upgradient edgeof the model.

r-9-

You will use a realistic re-charge flux.

You will use a more realistic salt concentrationin the recharge.

You will use a realistic rate of contaminant re-lease from the site to the ground water.

Assumption for the model will be clearly explainedand justified.

Verticle and horizontial contaminant profiles ver-sus time will be used to present the model results.

To check for the effect of movement into the clay confining layer,implement the model processes described in the attached letter fromEd Neid of Roy F. Weston.

Page 5-23:

You must clarify that SUTRA was only to define the movementof the NaCl.

Page 5-24:

Describe what you mean by "presumed area of salt water in-fi1itration." Fig 4-8 is the wrong figure. However,Figures 4-4 through Fig 4-7, shows no evidence of a groundwater mound. That is there is no indication of flow in bothdi rections.

Page 5-28:

a. Lines 5-11:

For the model, use contaminants levels that are present. Thatis phenol, kptones, methylene chloride and cyanide. Use thehighest concentrations detected from all wells within the plumenot just D30 and A30.

Page 5-29:

a. Lines 10-11:

There is no proof that either the metals nor the organics of con-cern would decay of removed with high efficiency. Therefore,this statement must be corrected.

h. Lines 12-13:

Predicted exposure point concentrations must be tabulated and com-pared to standards.

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Figures 5-12A and 5-12R

Make the dif ference between these plots clear in the heading.

Section 6 (See 5/20/87 Memo from Mike Stapleton;attached):

a. The data used for input to the risk assessments must be clearlyidentified.

b. All calculation steps and assumptions must be clearly presented.

c. The risk assessment of the no action alternative must assume thatno corrective actions take place and that no restrictions areplaced on future use of the property. Therefore, it should eval-uate the exposure from future development on the property and fromtrespass of the property. It appears that both industrial andresidential development are possible. It should assume that a wellcould be placed any place on the property, and soil ingestion usingtest data. It should also evaluate acute exposure fron digging onsite via a trespass or on-site construction mode.

d. Even within the 10,000 TDS plune the risks of exposure due to in-cidental ingestion, and various industrial useages must be eval-uated.

e. You should describe how environnental impacts will be evalauted.

f. For each exposure pathway, the indicator parameters should be corn-pared to relevant standards and the subchronic, chronic, and car-cinogenic risks presented. This will clarify which exposure pathway is of concern. For example, Tables 6-8, 6-9, 6-10, 6-11 and6-12 identify derma, ingestion and inhalation intakes, but thereis no way to tell whether the ingestion of concern is from drinkingwater or soil ingestion, nor whether the inhalation hazard is due tovolat i l izat ion of chemicals on site or in the household from potableuse. Furthermore, the risk values presented are only cumulative.

g. The well inventory has shown that residents do sometimes installshal low (that is 10 ft deep) in this area. Shal low wel ls could drawwater from just the top portion of the shal low aquifer. Therefore,the upper portion of the shallow aquifer must be considered an expo-sure point if it is less than 1U,000 TDS even if the lower portionof the aquifer is greater than 10,OOU TDS.

Page 6-2:

"Exposure to contaminants can occur when:

0 Contaminants migrate to human exposure points.

0 People t respass on the site.

0 Development of land containing contaminants mediabrings peoples into contact with the contaminants." (1)

(*' CHpM-Hil l , Remedial Investigation Volume 1, Seymour Recycl ingCorporat ion. May 12, 1986. Page 9-18.

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The Midco I RI l ists only exposure pathways for contaminantsmigration to human exposure points. In addition, bioaccumu-lation (that is from f ish & wildlife ingestion) is not listed.This must be corrected. You should also clarify what is meantby soil transport fron contaminated soi ls . List transport/exposure pathways that inapplicable and why. In addition, therisk assessment does not simply "compare concentrations of con-taminants under current conditions with applicable and relevantstandards" but compares concentrations from various potentialfuture use scenar ios with applicable and relevant standards.

Page 6-4: lines 5-6:

The RA is actually part of the RI. This must be corrected.

Lines 9-10:

Uncontrolled hazardous waste sites can almost never be des-cribed as being at "steady state." A more accurate descriptionwould be that the RI determines the potential for contaminantsmovement from the site. This must he corrected.

Page 6-7; lines 12-14:

It must be made clear that you are not only evaluating exposurefrom migration of contaminants from the site but also exposurefrom human use of or trespass of the site.

Page 6-10; lines 5-8:

It is not true that transport in surface water and the atmosphereare not normally evaluated in the RI. Therefore, this statementmust be corrected.

Apppndix FR, Section 6.3 (Indicator chemical selection process):

a.) You must repeat the indicator chemical selection process withthe following changes:

Eliminate residential wells, "off-site ground water," and"off site soils" from the calculations. Also eliminate"background" samples included in other categories inclu-ding "on-site ground water," "surface water," "on-sitesoils" and "sediments."

Incorporate data improperly deleted from the selection pro-cess including data on cyanide, methylene chloride, acetone,ketones, pesticides and other compounds. The selectionprocess must use all validated data.

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compounds without establ ished toxicity constants shouldnot be excluded.

cyanide, ketones as a group or as individual compoundsand methylene chloride must be included as indicators ifthey are present off-site.

e. The related chemicals process should be included in the dis-cussion of the indicator chemicals.

f. On page 24 of the Public Health Evaluat ion Manual it isadvised that all compounds on-site that do not have toxicityconstants should be listed.

Ris (2-ethylhexyl)phthalate and n-nitrosodiphenylamine shouldnot be considered related chemicals.

Page 6-15:

The name "toxicity evaluation" is inconsistent with "toxicityassessment "outlined in Figure 6-5.

Page 6-19; line 11:

It is no longer true that "ERA considers MCL 's NAAQS and federallyapproved state water qulaity standards "are the only potentiallyapplicable, or relevlant and appropriate standards." This waschanged by SARA. The new policy is under development. Therefore,this statement must be corrected.

Page 6-21:

Identify what GDI stands for.

Page 6-22:

The RI report can not be used to evaluate U.S. EPA procedures, pollcies or decisions. Therefore qual i f iers such as "a great deal ofconservatism," and "EPA considers animal evidence quite liberally..and, in the process, probably includes fa lse posit ives in itsestimates" must be removed.

Page 6-24:

You must identify which soil samples were used for calculating back-ground levels. You must identify what chemicals were eliminatedusing this process. Some highly soluble consituents should not beeliminated by this criteria since they could have been washed intothe ground water before the site cover was installed. I would l iketo see a comparison of on-site arsenic with background.

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Page 6-26; Section 6.4;

Section 6.2.5 is entitled "Risk Character izat ion" not "toxicity evaluation." There some to be a confusion of the terms toxicity evaluation,toxici ty assessment and risk character izat ion. This should be cor-rected.

Section 6.4.2:

This discussion would be better left completely in the Appendix.The information provided is quite technical and detailed and isnot helpful to the average reader. It is confusing that you in-cluded much information on carcinogenic effects in a sectiontit led "Noncarinogenic Effects." Where specif ic results are re-ported, references should be identified.

Page 6-42:

The source can and should be quantified using the avai lab le samp-ling results.

Page 6-43; Paragraph 1:

Table 6-4 does not indicate that oxidation-reduction is an importantprocess influencing the fate of nickle, arsenic and lead. Thismust be corrected. It is not proper to cal l adsorption, ox idat ion-reduction and volati l ization fate processes since it implies thatthese are the final fate of the chemicals rather than simple trans-formation that affects the transport of the chemicals. Th is mustbe corrected. Adsorption does not prevent migration. This must becorrected.

Page 6-43; Paragraph 2:

You must add the fol lowing additional mode of environmental transport:

1) Discharge of contaminated ground water to nearby sur facewaters.

Page 6-5; and page 6-44 to 6-47:

a. The site cap dries out in the summer and so wi l l not preventvolat i l izat ion. By far the highest volatile organics con-centrat ions are on site. Therefore, volat i l izat ion from on-site so i ls must be evaluated including the nearby businessas an exposure point.

b. Direct ingestion of on-site soils must be included in the eval-uation.

c. The third paragraph of page 6-46 does not make sense. Thismust be corrected. Contaminants were not tested in LakeMichigan nor the Grand Calunet River.

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d. Data used for input to each exposure pathway should be clearlyidentified, along with calculations and assumptions used in cal-culating exposure hy each pathway.

Section 6.5.4:

You must clarify what you mean by the last sentence on page6.53.

Section 6.6.1 and Table 6.2:

All parameters must be compared to relevant standards in tableand naps in Section 5. The comparison can not be restr ictedto the indicator parameters or the results for well 030.

It must be noted that the pond north of Midco I could at leastoccasional ly be used for swimming, and is used for fishing.

Page 6-56:

You have not proven that barium is not related to the Midco site.In fact it is elevated in the test pits. Therefore, yoj can notstate that barium is not related to the site.

Section 6.6.4:

This section must be modified to reflect the results fror implemen-tation of the previously listed changes.

You must clar i fy what is meant by the risk to off-site residents.

Table 6-7:

What happened to barium in soil?

Section 7.1:

This sect ion must be rewritten to reflect conclusions resulting fronimplementation of the changes previously listed. In addition, rele-vant required changes listed for previous sections also apply tothis section.

Section 7.2:

The FS goals must be rewritten to be consistent with the Consent Dec-ree and the NCR.

It must be noted that the on-site contamination is also a source ofsurface water contamination.

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Section 7.3:

The FS must evaluate a range of al ternat ives. Based on this evalua-tion, it will he decided which act ions are or are not reasonable.

Therefore, you nust eliminate the statement that, "any reasonableremedial action.....will require elimination of the salt source."This wil l be decided after at least a preliminary evaluat ion of re-medial actions in the FS. In addition, references to cost sharingand responsible parties must be removed from the RI.

The list of potential remedial actions is helpful. However, youshould be aware that the Agency will require pre-screening of a muchlarger array of potential remedial actions. You should begin todevelop and screen these alternatives now in accordance with Sub-task 6.1 and 6.2 of Exhibit B of the Decree. You should submitthe preliminary l ist of potential remedial actions and your re-commended preliminary screening to the Agency next month for ourreview.

Page 7-5:

Unless more information is provided, you can not state that accessrestrictions would eliminate exposure to site soils.

Page 7-3:

I was told by Weston that it may be possible to purge and treatthe most highly contaminated ground water without drawing in highconcentrations of salt.

Page 7-9:

If a slurry wall is installed around the site, a cap would pro-bably also be required.

Appendix FD:

a. Page 2, Section D.I.4: Somehow you have switched fronarsenic to barium. This must be corrected.

100 CORPORATE NORTH. SUITE 10!ROUTE 22 AND LAKESIDE DRIVEBANNOCKBURN. ILLINOIS 6001 5(312)295-6020

3 June 1987

Mr. Richard BoiceU.S. Environmental Protection Agency230 South Dearborn12th Floor NortheastChicago, Illinois 60601

Subject:Work Assignment No.:EPA Contract No.:Document No.:

Dear Mr. Boice:

Midco I Modeling173-5L0968-01-6939291-TS1-EQYH-1

Subsequent to our meeting on 29 May 1987 at which wediscussed the groundwater modeling being done for the Midco Isite with the PRPs consultant ERM, I spoke with Dr. KerosCartwright of the Illinois State Geological Survey about themodels. The specific issue be raised, which he referred toas "water balance11, concerns the fact that there will be someflow of water from the base of the sand and gravel aquiferinto the underlying confining bed. Although this volume willbe small and can usually be ignored without causing anyproblems, it may need to be specifically accounted forbecause of the salt in the system. Thus, we should requestthat ERM assess the effect of this flow on their model asfollows:

o Boundary Condition Set I: Upgradient, recharge anddowngradient set at constant flux; bottom set atno-flow.

o Boundary Condition Set II: All boundaries set atconstant flux.

These runs will allow an evaluation of the sensitivity of themodel results to this small flux condition.

Very truly yours,

ROY F. WESTON, INC.

Edward A. Need, P.G.Senior Hydrogeologist

EAN:kte

r r

United States Department of the InteriorFISH AND WILDLIFE SERVICE IH *"LV """ T0:

BLOOM INGTON FIELD OFFICE (ES)718 Nonh Wilnut Sireti

Blooroingion, Indiana 47401

M?V 11, 1987

Richard Boice (5KF-1S)U. S. Environmental Protection .AgencyC5ECLA Enforcement230 S. Dearborn Street

IL 60604T'r.*•"*"re?porv*s to your request for our comments on the ecology section of the

second draft of the Kidco I remedial investigation (RI). The followingcement? were discrsse"" *''ith you in a phore conversation with Don Steffeck ofmy staff on May 7, 19£7. In general, this draft is an improvement over thefirst draft, however, the following specific cements should be adcire-sse-r" inor^pr that accurate 2nd complete information is presented.

PP C. 4_o. i5_pe IP: Th? sentence identifying the birds seen in the are-n shculilinclude a description of the time frame the observationswere made (ic. hours, days, months) and the surveytechr.ique used (ie. casual observation, line and transect,etc.)."

Page 4-9; end of first full paragraph: In order to clarify this paragraph werecoTTT?e cJ the following sentence be incorporated at the endo* thjp paragraph. "Waterfowl and other species ofmigratory birds have been reportedly observed feeding andnesting in the ar»=."

= 4-Q: second paragraph: It is stated that no endangered species were seenin th^ vicinity o* the site. This report should includethe qualifications of the observers and the methodologyused to substantiate this statement. Is this informationbased on casual observation, a detailed survey utilizingestablished biological survey techniques, or some variationof these methods?

Page 4-10; first par rs h: first sentence: To be fully accurate we recommendthis sentence be changed to the following: . . . drinkingwater and by reducing and/or contaminating the flyingaquatic insects . . ."

Pag» 4-1 f1; second paragraph: It is stated that no endangered plants were foundin the vicinity, we have the same conrrent as stated forPage 4-9, second paragraph.

2.

Page 4-11? l^st p-5ragrD:;u c^ t^o Ecology section: The American bittern andFranklin's ground squirrel were both observed in thevicnity of P.icicc I by personnel from this office. In factFranklin ground squirrels were trapped several tiroes during

^ .;»"•> our field collection efforts. This paragraph should becorrected to reflect this information.

"We looV. forv?r to providing you ccrments on the Midco I RI as necessary. Itis our understanding th-.t the other sections of this second draft RI will bereviewed by you baser* on the conrnents we provided for the first draft. If youhave any questions r«qar£ing the corrrrents presented in this letter, pleasecontact Don Steffec>: of nv staff.

gincirely yours,

David C. Hudak,SuDorvisor