Document 15z7E99QgmLgNYBOXJNYBX3OE

FR) F li LD) (= BAlVRsOWEN[TARLSRESONURCaE G?RP ENVIRONMENTAL RESOURCE GROUP MEMORANDUM DDaavvee DDouoglausaangnddMlMaraa rkkRRsyyss COMPANY: Timms Poin Cat Ages Minnesota Pollution Control Agency FROM: Son Coon and Pat Bock Dan Comeau and Paul Book DATE: ena 10.208 February 10, 2003 RE: 4 Cotoge Grove eaD1 id runs Sarg sis 3M Cottage Grove; Area D1 Initial Groundwater Sampling Results NOTES/COMMENTS: Exceed ar the ltrs any! sus fam row ening wes (WLI01 and Enclosed are the laboratory analytical results from new monitoring wells (MW-101 and MMWW-1-10022)) wwhhiicchh wweerree rreecceennttllyy iinnssttaalllleedd aatt tthhee DD11 aarreeaa ooff 33MM CCoottttaaggee GGrroovvee.. TThhee wweellll ov 55 soo eohonon Foe locations relative to the D1 source location are shown on Figure 1. `SSaammpplleess ffrroomm tthhee wweellllss wweerree ccoolllleecctteedd bbyy EEnnvviirroonnmmeennttaall RReessoouurrccee GGrroouupp,, LLLLCC ((EERRGG)) oonn DDeecceemmbbeerr 33,, 22000022 aanndd sshhiippppeedd oovveerrnnigihgtohontn iiccea ftoo EExxyyggeenn RReesseeaarrcchh,, IInncc.. ((EExxyyggeenn)) ffoorr tthhee rreeqquueesstteedd aannalayslesoyofsfeeieigghshtt fflluuoorrooccaarrbboonn ((FFCC)) ccoommppoouunnddss.. aQnNaQcC since 10 you rviousty, Exon ei and resued i priinry eer doe As indicated to you previously, Exygen revised and re-issued its preliminary report due 1s cy ssamemavaty, ona (OAS) Seve "Seven of he ag epvets to quality assurance/quality control (QA/QC) issues. Seven of the eight requested nas rs Soot hd as td CHG Sos ws sss compounds were successfully analyzed and quantified. QA!QC issues were associated ne C1 308 Cera: 20 sree dase be Soci 55 of fo with the C4 acid (Heptafluorobutyric acid) analyses. As indicated in Section 5.7 of the boat ovo. he G4 323 ras Fd ow pk robes an 96 nl et in lllaaabbbooorrraaatttooorrryyy rpperrpoototoorctc,ooltlssh..e CSS4aammapcplildee aqqunuaaanlntyitsitteaasttiiohonnadffoolrrowtthheespCCik44e aarceciicddoviises rinneoostt arreneppdoordrttiededdniionnt EEmxxeyyeggetentnh''ses To ato opt. final laboratory report. ux Ansis Flux Analysis Using he Decor 2002 sal ana dt fem th nw manor wes, ERG Using the December 2002 sample analytical data from the new monitoring wells, ERG Cres OF FC roms ho a si Ft po So Sot evaluated D1 FC groundwater flux to the Mississippi River, approximately 600 feet south of Br Tro ovation es 3 ows cena sn Bt FC soos D1. The evaluation uses an overly conservative assumption that all FCs measured in the ror wh Gash oa tho eat, Ths orcas wom bl ovo groundwater will discharge to the river without attenuation. This exercise will show that even oan ing vy nsoRat Semone. XS Gor conor va Tov when using very conservative assumptions, existing groundwater conditions will not cause mobos sea exceedances of receptor risk. To kong torshpvas usd octet FC contr hee The following relationship was used to estimate FC concentrations in the river: [tte ntiztre) 110000001I0DSSCCenetneterr,,5800SSoouutthhEEigighhtthhSStrtreeeett,,MMininnneaepaoploiliss,,MMNN 5555440022 Phone:612.339.4750 Fa~612.339.4990 Seon Exhibit 11888811 State of Minnesota v. 3M Co., Court File No. 27-CV-10-28862 Suponciso 3MA00046947 11888811..00000011 MFMoCPCnAAeD,D!11MM0,ee2mm0so0ar8anndduumm Pager Februa~ Page 2 10,2003 CCoonncceenntrtatrioantAiqouinresr ** DDiiscshacrgheaArqyugiufeer == CCoonncceennttrartiaotniRoivne.r ** DDiisscchharagregReivse.r 11888811..00000022 3MAC046948 3MA00046948 VPOAD! amram MPCA D1 Memorandum frttriy February 10, 2003 Poet Page 4 REE satenslom HHyyddrraauulliicc CConoducntidviutyctivity ((KK)) K = 27.7 gallonslday/ftz EIERRMGG uuEsseeddRtthhoee hhyyyddrraaPuulliiEcc ccEoonnddnuucc.cttiivnviltyyfvvaalFluuoee reessattiinmmaa1ttee0dd9ffoFrr ttahheo mnneeoaardroeessttlssiitIteeemmsatorgniaiotoirrioinnngg wel well Reportfo Cottage Grove. (MW-13) by Roy F. Weston, Report for Cottage Grove. Inc. in the February 1986 Final Remedial Investigation tUUhsseiinncggqutthiheeersseelleecctteedd pure plume width width and and haul hydraulic conduciiy, conductivity, ththe discwhasacalrculgateed discharge was calculated erfor the aquifer: K=2425737gpaainne) Aquifer Discharge : WW == 330000 ((ffeeeelt)) K = 27.7 (gpd/ft2) 2.493 gal/min Thedischargevalue usedforth sri the west con7-sdayastccamifowvelye0 The discharge value used for the river is the lowest consecutive 7-day streamflow likely to acct na 10yearperiod 110) Thal value (obtfaomineisd1.5 ikongalonspor occur in a 10-year period (7Q10). That value (obtained from __.) is 1.5 billion gallons per Gaoyr 1.0a4lon1spe.rmi6de6gp7m) Based on he assitmatpontyhaolfnhe ow day or 1,041,667 gallons per minute (gpm). Based on the assumption that only half the flow 97th hor iui mich he aqui. Gscharge vale of 52033a was ued of the river would mix with the aquifer, a discharge value of 520,833 gal/min was used in EERRGG''ss aannaalylyssisis.. Aquifer concentratiwoenresbasedon analyte ess rom theDecember2002sapling Aquifer concentrations were based on analytical results from the December 2002 sampling vent as summarized bow: event as summarized below: AvocaRsuly -ocemie 002 D1 Analytical Results - December 2002 [mse |5emgoo| w16m | TmOi o a|| so[|3w7o|i|EWUmaE)|| Sample ET BT = 0NE OE OE) Lab Duplicate [Feira] | ums | 0 | so mw | wa Field Duplicate 0 3 Average Total SUM FCs MW-101 (ppm) MW-102 (ppm) 2.87810 .8855 2.95560 2,77880 2.87083 .9769 .g057 ,92270 PFOA MW-101 (ppm) MW-102 (ppm) .17000 ,324.0 .18000 404.0 .17200 ,369.0 .17400 365.67 PFOS MW-101 (ppm) rClW-102 (ppm) .32500 .3840 .35600 .3940 .35800 .3360 ,34633 _37133 fresno[ome[ove [om[om[om| (Averageppm)= 2.8708 0.9227 0.1740 0.3657 0.3463 0,3713 Concentration DischargEsqas = Concer* DSchorGOme Concentration~quifer * DischargeAqu=ter = ConcentrationR=ver * DischargeR~ver or Diatgons CCoonncceenntrtatrioant~iivo~n., == CCooncenntcratieonnAqt.if~rr**aDDiistscchiahragoerAgnqeu=s;~:r DischargeR~vcr 11888811..00000033 mAcocseas 3MA00046949 m=eeen MPCA D1 Memorandum February 10, 2003 Page 5 hAe naly yte Well rome Groundwater Analytical ReRseuslutltss ((ppppmm)) Dec. 2002 FoePredicted River CCoonncecnetnrtartaitoionn) (ppm) SSttaannddaarrddss ((ppapwmn)) o Wem| oats PFOA | MMWWr-1o01t | 00..41774400 PFOA |wMiW-1z02 | 003.3665577 PROS | WWam | 03463 eseeer| |446.1E6E0-077 | |878.s75eE0-0r7 | |BZ9E07 | HBV HHBBVV MHeBvV HBV. |fooeos| |770.000EE0-033 | |707.0005E0-033 | |100E03| The current Cottage Grove NPDES discharge standard for total FCs and the interim health ETS) ER Sy bbaasseedd vvaalluueess ((HHBBVV)) ffoorr PPFFOOAAJ/PPFFOOSS rreecceennttllyy ddeevveellooppeedd bbyy tthhee MMiinnnneessoottaa DDeeppaarrttmmeenntt ooff Eee Health (MDH) are summarized above for comparison to the predicted river FC Em ST SE TET concentrations.There are no known users of the river for drinking water between Cottage Grove and the junction of the Mississippi and St. Croix rivers. teetenhosomneotpsrggsovere As shown above, ERG's evaluation of potential groundwater discharge effects to the river Cp eo (given the FC concentrations present at D1 in December 2002) indicates groundwater FC levels at D1 should have no adverse effects on Mississippi River water quality. em ee ERG proposes conducting the second and final sampling of the two new wells at D1 the ETE ww eeke ooffFe Feebbrruk uaarryy 2244,, 22000033.. TThhee aannaalylyttiiccaallddaattaaffrroomm tthhaatt ssaammpplliinngg eevveennttwwililll bbeepprroovviiddeedd ttoo fos Tes mT ne you when it becomes available. Please contact Dan Comeau (612.339.2478) or Paul Book (612.339.4779) of this office or Todd Fasking at 3M (651.778.5344) if you have any questions or comments concerning the information provided in this memorandum. Enclosures (As noted) CC: Mr. Todd Fasking, 3M ET & SS Mr. Mark Gaetz, 3M ET & SS 11888811..00000044 worn 3MA00046950