Document bB9O93ym7L5qME7JYRxXarm56

I I I 1 22001111 AANNNNUUAALL GGRROOUUNNDDW WAATTEERR RREEPPOORRTT I 1 PPEERRFFLLUUOORROOCCHHEEM MIICCAALL ((PPFFCCA))NGGDRROOUUNNDDWWAATTEERR AASSSSEESSSSMMEENNTT I 1 HHYYDDRRAAUULLIICC CCAAPPTTUUARRNEEDZZOONNEE EEVVAALLUUAATTIIOONN I 1 33MM W WOOOODDBBUURRYY,, M MNN I I I 1 NNOOVVEEM MBBEERR 2011 2011 I I I I I I 1 by I 1 WesWWtEECShSeTTsOOteNNr,SSOPOeLLnUUnTsTIyIOOlNvNSaSn,,iaIINNC1C.9.380 West Chester, Pennsylvania 19380 I 0022118811..222222..001188..00000011 1I So 1 3379 I M_MNO4998454 3M MN04998484 33337799..00000011 I I 1 I 1 SSeeccttiioonn TTAABBLLEE OOFF CCOONNTTEENNTTSS. PaPaggee I 1 INTRODUCTIONwoes1 1 11 REMEDIAL DESIGN/REMEDIAL ACTION (RD/RA) PROGRAM. ccc. 1-1 INTRODUCTION.......................................................................................................... 1-1 1.1 REMEDIAL DESIGN/REMEDIAL ACTION (RD/RA) PROGRAM ............... 1-1 I 12 CHRONOLOGY OF RECENT ACTIVITIES. SE 1.2 CHRONOLOGY OF RECENT ACTIVITIES ...................., ...............................1-2 1 3 SAMPLINGPROUBAM mmission Bl o SAMPLING PROGRAM .............................................................................................. 2-1 I 21 GROUNDWATER SAMPLING PLAN 21 2.1 GROUNDWATER SAMPLING PLAN ............................................................. 2-1 1 22 GROUNDWATER SAMPLING EVENTS 21 2.2 GROUNDWATER SAMPLING EVENTS ........................................................ 2-1 I EE -- o HYDRAULIC EVALUATION ..................................................................................... 3-1 1 33..11 M MOODDIIFFIICCAATTIIOONN OOFF MMOONNIITTOORRIINNGG W WEELLLL MMWW-6-6LL. SSE ..................................... 3-2 ! 32 BOREHOLE GEOPHYSICS... EE 3.2 BOREHOLE GEOPHYSICS ............................................................................... 3-3 1 33 WATER LEVEL MONITORING crc 35 3.3 WATER LEVEL MONITORING ....................................................................... 3-5 I RESULTS .................,..................................................................................................... 4-1 1 41 GROUNDWATER RESULTS. dl 4.1 GROUNDWATER RESULTS ............................................................................ 4-1 I 411 Sentinel Well +1 4.1.1 412 Baier and Monitor Well Rests Tas 4.1.2 1 $15 Red WenSeng Res Th 4.1.3 Sentinel Well ......................................................................................... 4-1 Barrier and Monitor Well Results ......................................................... 4-3 Residential Well Sampling Results ....................................................... 4-3 I 42 HYDRAULIC EVALUATION RESULTS, " 4.2 HYDRAULIC EVALUATION RESULTS ......................................................... 4-4 421 Darier Well Flow RateDal. ed 4.2.1 1 22 Wor Lovl Mearement oo 4.2.2 I 423 GrouEnlevadtiown CaonttoureMaprs. 4s 4.2.3 Barrier Well Flow Rate Data ................................................................ 4-4 Water Level Measurements .................................................................. 4-4 Groundwater Elevation Contour Maps ................................................. 4-5 I 6 RECOMNENDATION women FINDINGS ...................................................................................................................... 5-1 RECOMMENDATIONS ............................................................................................... 6-1 I ! I I I mero I M3M_MNMON409499988448855 33337799..00000022 1 1 =e 1 FFIIGGUURREESS FFiigguurree PPaaggee I Figure 1-1 Well Location and Topographic Map ...................................................................... 1-5 1! FFiigguurree 22--11 GGrroouunnddwwaatteerr MMoonnititoorriinngg Network... rn Network .......................................................................... 22-33 Figure 3-1 Geologic Cross Section Transect ............................................................................. 3-7 I igre 2 GoClossgS i 003 Figure 3-2 Geologic Cross Section ............................................................................................ 3-8 1I Fig PFBA Sump Result. nT Figure 4-1 PFBA Sampling Results ............................................................................................ 4-7 B!o rie 2 rron seamiRenngt Figure 4-2 PFOA Sampling Results .......................................................................................... 4-8 I rine 43 PrOSSupRleistgo nc Figure 4-3 PFOS Sampling Results ........................................................................................... 4-9 I Fig 4Groundwater Elston Contour Mop-Salow Wel Papin Figure 4-4 Groundwater Elevation Contour Map-Shallow Wells Pumping I Conditions October 21, 2010 .................................................................................. 4-10 I bie 5Gombe ivi CoompShoo FriDuin Figure 4-5 Groundwater Elevation Contour Map-Shallow Prairie Du Chien ! Wells unpinCoins October 21, 2010. tt Wells Pumping Conditions October 21, 2010 ........................................................ 4-11 Ibo oma Bin Corb rn Ast Ot, 300412 Figure 4-6 Groundwater Elevation Contour Map-Jordan Aquifer October 21, 2010.............. 4-12 I Fis 47 Grounbvar Bison Contour MapShallowWells PringCondon Figure 4-7 Groundwater Elevation Contour Map-Shallow Wells Pumping Conditions II Nay 19,000 ars May 19, 2011 .......................................................................................................... 4-13 I Figure +8 rounderEivaton Contour WieShallow PrisDuChien Figure 4-8 Groundwater Elevation Contour Map-Shallow Prairie Du Chien i W `Weellllss PPuummppiinnggCConodnidtiitioonnss M Mayay 1199,,22001111 " nmin ............................................................. 4-14 JI Fe min Cond py 0 1 Figure 4-9 Groundwater Elevation Contour Map-Jordan Aquifer May 19, 2011 ................... 4-15 I Fig 410Groundwater Elation Cour Mip-Shallow Wels Papin Codions Figure 4-10 Groundwater Elevation Contour Map-Shallow Wells Pumping Conditions 1I OBI, 16 October 31, 2011 ................................................................................................... 4-16 I1I i I mo 3M MN04998486 33337799..00000033 11I pes) I ! 1 Wells Pumping ConditionsOctober 31,2011 rr... an Figure 4-11 Groundwater Elevation Contour Map-Shallow Prairie Du Chien Wells Pumping Conditions October 31, 2011 ...................................................... 4-17 I FFiigguurree 44--1122 GGrroouunnddwwaatteerr EElleevvaattiioonn CCoonnttoouurr M Maapp--JJoorrddaann AAqquuiiffeerr OOccttoobbeerr 2211, , 2200110.0.....................44--1188 1I 1I ! 1 I 1 ! 1 I 1 I i 1! 1I I 1 |I } 1I I1v,I ; ~~OLDERS.(~-8~3M-Woo~b~t~WESTON-REPORTS~011,,AnnuaI-Reper~Ol I Annual Repot[ 'v~dbury (FINAL).d~ iii i 3M MN04998487 33337799..00000044 !1 Ee 1 PEi Table Tile 241 Table 2-] BI tu 22 Table 2-2 I! Ti 1 Table 4-1 TTAABBLLEESS agePage CrmbvatrMosiriPng. i as Groundwater Monitoring Plan................................................................................... 2-4 GrommeetC Sanling Ev Sie Octob0e0r, 2s Groundwater PFC Sampling Events Since October 2010 ......................................... 2-5 CrouPRmCAwnat Da Oster 2010ore201 Groundwater PFC Analytical Data-October 2010-November 2011 Sampling Events ...................................................................................................... 4-19 I Table 4-2 Barrier Well Flow Rates .......................................................................................... 4-23 I Table 4-3 Depth-to-Groundwater Elevation Data-October 2010-October 2011 ..................... 4-24 I 1 I 1 I 1 I 1 1I ! I 1 1I 1I 1'I - - % I 3M MN04998488 33337799..00000055 Il ! CRE E I jIe somaw------ 1 AATTTTAACCHHMMEENNTTSS ATTACHMENT A MW-4L AND MW-6L BOREHOLE GEOPHYSICS I ATTACHMENT B1 DATALOGGER HYDROGRAPHS Po rmommon suvoaorwinosocaums I ATTACHMENT B2 MANUAL DTW HYDROGRAPHS 1I II 1I 1I II II 1I 1I II 1I 1I 1I .I1 DtAo A rt 3 ndei I I 3M MN04998489 33337799..00000066 I I 11.. IINNTTRROODDUUCCTTIIOONN I "This This report report hhaass bbeeeenn pprreeppaarreedd bbyy WWeessttoonn SSoolluuttiioonnss,, IInncc.. ((WWEESSTTOONN)) ffoorr 33MM CCoommppaannyy 1 and and is is the the annual annual report report tthhaatt iinncclluuddeess aann aasssseessssmmeennttoofftthhee ggrroouunnddwwaatteerr aatt tthhee ffoorrmmeerr 33MM I W Wooooddbbuurryy ddiissppoossaall ssiitee,, iinn W Wooooddbbuurryy,, MMNN ((thhee sstitee)).. TThhiiss rreeppoorrtt ccoovveerrss tthhee OOccttoobbeerr 1 2010 through November 2011 time-frame. 2010 through November 2011 time-frame. I 1 11.11 RREEMMEEDDIIAALL DDEESSIIGGNN//RREEMMEEDDIIAALL AACCTTIIOONN ((RRDD//RRAA)) PPRROOGGRRAAMM I 3M entered into a Settlement Agreement and Consent Order (the Agreement) in May 3M entered intoa Settlement Agreement and Consent Order (the Agreement) in May 1I 2007 with one purpose beng the conducting of remedial invesigatons and response actions 1 address perfluorochemicals (PRC)a the sit (se Figure 1-1forthe location). 2007 with one purpose being the conducting of remedial investigations and response actions to address perfluorochemicals (PFCs) at the site (see Figure 1-1 for the location). 1I In sscodance with th Agreement been 3M and the MPCA, 3M hasbeen conducting remedial investigations and response actions to address PFCs present at the sit. As In accordance with the Agreement between 3M and the MPCA, 3M has been conducting remedial investigations and response actions to address PFCs present at the site. As 1I required by the Agreement, 3M submited to the MPCA a Remedial DesignResporse Action (RD/RA) Plan for addressing the PFC at th ste in April 2009. MPCA provided required by the Agreement, 3M submitted to the MPCA a Remedial Design/Response Action (RD/RA) Plan for addressing the PFCs at the site in April 2009. MPCA provided 1I technical comments to 3M on the Woodbury RIVRA Plan nd a response to comments letter was submited by 3M to the MPCA in May 2009. The MPCA approved the technical comments to 3M on the Woodbury RD/RA Plan and a response to comments letter was submitted by 3M to the MPCA in May 2009. The MPCA approved the 1I RD/RA Plan inthe eter to 3M dated Jue 1, 2009. The RRA Plan speifes on tem groundwater monitoring network for the sit to be implemented afer response RD/R Plan in their letter to 3M dated June 1, 2009. The RD/RA Plan specifies a longterm groundwater monitoring network for the site to be implemented after response 1 tons tthe site Have been completed. actions at the Site have been completed. I 1 TThhee eexxccaavvaattiioonn aanndd rreemmoovvaall ooff ssooiillss ccoonnttaaiinniinngg PPFFCCss iin tthhee ffoorrmmeerr MMaaiinn DDiissppoossaall AArreeaa I wwaass ccoommpplleetteedd iinn FFaallll 22000099 aanndd tthhee eexxccaavvaattiioonn aanndd rreemmoovvaall ooff ssooiillss ccoonnttaaiinniinngg PPFFCCss iinn 1 the former Northeast Disposal Area was completed in Winter 2010 (final grading and the former Northeast Disposal Area was completed in Winter 2010 (final grading mad I sseedeingewwadassccioommpnlpeletgteedd iinn MMaayy 22001111).). I1 Meter tthe MFCA from 3M questing approval 0 reduce pumping rom te Barer AWellestterattothteheWMooPdCbAurfyromsite3Mwarseqsuuebsmtiintgeadpp10rotvhael tMoPreCdAuceonpuMmapricnhg f1r6o,m20th10e.BaTrrhiiesr Wells at the Woodbury site was submitted to the MPCA on March 16, 2010. This 1 request for reduced pumping also included a groundwater monitoring plan to document I trehaqtuegsrtoufonrdwraetdeurcecdapptuumrepiwnoguladlsosililncbleudaecdhiaevgerdouwnhdiwleatpeurmmpionnigtofrrinogm ptlhaenBtaorrdieorcuWmelelnst that groundwater capture would still be achieved while pumping from the Barrier Wells I} is ces. MPCA comment 0 the Match 16, 2010 eter regs wes srt 0 3M in is reduced. MPCA comments to the March 16, 2010 letter request were sent to 3M in a 'I A I S3MM_MMNND044S99988449900 33337799..00000077 I I1 10% 5, 200 tw a oS i, 6 gti June 30, 2011 letter and it included requirements for expanding the groundwater ' AS rR Worfee monitoring network proposed in 3M's letter request. Following the completion of several I wate aoe set Bo 08 re repens wrt infrastructure changes to implement the Barrier Well reduction program, 3M sent a 1 sere 2 os THO apts te oot ey To TE Tom WE response to these MPCA requests in a letter dated January 12, 2011. The MPCA I Br Aa requirements, in conjunction with the groundwater monitoring network for the site 1 res KDA Pn vet doCros Sing nr presented in the RD/RA Plan, were used to develop a Groundwater Sampling Plan for the I Soy ie. Te Grube Sapling Pn (WESTON, ft 2011ws ted Woodbury site. The Groundwater Sampling Plan, (WESTON, June 2011) was submitted t roa rs TT ee re remem to the MPCA on June 16, 2011. Approval of the Sampling Plan with comments was I pprorviodevdbbiyy dMMPePCCdAA iinnleletttteerrttoo 33MMdadatteedd AAuugguusstt 2233,, 22001111.. 1I gh pr HRA im es i amps The MPCA approved RD/RA Plan indicates that the three components that will be I 1 aaddddrreesssseedd bbyy tthhee RRAA lloonngg--tteerrmm mmoonniittoorriinngg ppllaann ffoorr ggrroouunnddwwaatteerr aass ffoolllloowwss:: 1 * VVeerriiffiiccaattiioonn tthhaatt tthhee eexxttrraaccttiioonn ssyysstteemm mmaaiinnttaaiinnss hhyyddrraauulliicc ccaappttuurree ooff ssiittee I groundwater. 1I eri Sree pa Sr SR AB Documentation of groundwater quality as required by the Minnesota Decision 1 Pon Document (MDD). I reais oiposes Hea Ar a Documentation that treated groundwater is discharged in accordance with state I1 -- requirements. I1 SN 1.2 CHRONOLOGY OF RECENT ACTIVITIES 1 8 0 0 A Sate to pt wile As part of the long term groundwater monitoring at the site, numerous wells were I SS ---- TE Tomo ota TT identified to be sampled and analyzed for PFCs. The number of wells and the frequency 1 ofamweiebn he MPCvAed GratsSep Pn. The of sampling were established in the MPCA approved Grotmdwater Sampling Plan. The I Brrr Reve ate er aN Groundwater Sampling Plan includes wells identified to be sampled as presented in the 1 RH Te Or Ae Tetete RD/RA and additional wells as a result of the pumping reduction request. In order to I establish baseline groundwater quality data prior to the pumping reduction, the quarterly 1 iia sols po os id Outs 016. Sica rly groundwater sampling program was initiated in October 2010. Subsequent quarterly :I ------ VE ------_-- sampling events were performed in February, May and August 2011. i rere, Z:~'O LDE RS, ~-9~3 M~Wcodb~r~W ESTON-REPORTS~.011-Ann uaI-Ropor't~.011 ,~nual Report W~odbur~ (FINAL),d~ 1-2 I amosses 3M MN04998491 33337799..00000088 J II s On March 11,2011 the initial pumping reduction plan was implemented. The results of 1 the May 201 quel groundwater sping indicted for th ir tim, concentrations the May 2011 quarterly groundwater sampling indicated for the first time, concentrations I ofcetin PC in several sentinel wells te southern propery boundary. As a esl of certain PFCs in several sentinel wells at the southern property boundary. As a result 1 of thes detstions, and as agreed 10 with MPCA, 3M retumed Baier Wel B-2 10 of these detections, and as agreed to with MPCA, 3M returned Bamer Well B-2 to I erics and nea the puping rte a Bair Well 3 tos prediction pnping service and increased the pumping rate at Barrier Well B-3 to its pre-reduction pumping 1 rate on September 14, 2011. Additonal, M creased the sueyofsampling and rate on September 14, 2011. Additionally, 3M increased the frequency of sampling and I the number of wells 0 be sampled to collect additional data 0 alate trends. The the number of wells to be sampled to collect additional data to evaluate trends. The 1 following summarizes the timeline of events that cured and dona sapling ht following summarizes the timeline of events that occurred and additional sampling that I was performed ssosaed with he pumpin reduction program: was performed associated with the pumping reduction program: 1 + October, 2010: 1 annual sampling event October, 2010:1st annual sampling event. I 1 + FFeebbrruuaarryy,, 22001111::1~1*t qquuaarrtteerrllyyggrroouunnddwwaatteerrssaammplpilinngg.. I + March 2011 plemented the ist tp ofthe reduction in pumping by shuting March 2011: Implemented the first step of the reduction in pumping by shutting I1 doun Barr Well 52 1d recog pumping at 5.5 0 reduc the vel down Barrier Well B-2 and reducing pumping at B-3 to reduce the overall exacted groundwater flow rate by spprosimaily 175 gallons pes mins (GPM) extracted groundwater flow rate by approximately 175 gallons per minute (GPM) 1 (pprosimty 6d), (approximately a 5.8% reduction). 1I + April 22,2011 Monitoring well MW-6L was reconstructed (as MW-GLR) de 0 April 22,2011: Monitoring well MW-6L was reconstructed (as MW-6LR) due to I ockage in the well and concems of an impropes grout sea. The borehole blockage in the well and concerns of an improper grout seal. The borehole 1 geophysics program was aso completed at hse, geophysics program was also completed at this time. I 1 MMaayy 1199,,22001111::22na qquuaarrtteerrllyy ggrroouunnddwwaatteerr ssaammpplliinngg ppeerrffoorrmmeedd.. I + May 30, 2011; Annual Memorial Day weekend Baier Well shutdown for May 30, 2011: Annual Memorial Day weekend Barrier Well shutdown for I1 maineranee. maintenance. 1 + AAuugguusstt 2222--2233,, 22001111::33rd qquuaarrtteerrllyy ggrroouunnddwwaatteerr ssaammpplliinngg ppeerrffoorrmmeedd.. I + August 23, 2011: May quarterly groundwater sapling ruts sued by the August 23, 2011: May quarterly groundwater sampling results issued by the 1 irr. laboratory. 1I + Sepember 12,2011: WESTON provided an vaso ofhe d0a3M. September 12, 2011 : WESTON provided an evaluation ofthe data to 3M. 'I + Scpemiber 14,2011: 3M niall notified MPCA ofte bortory rests. September 14, 2011: 3M initially notified MPCA of the laboratory results. .I meee ~ kFOLDERS.0-9~3 M-Woodb~ y?~rESTON-RE PORTS'~2011 -A~n ual-I;~port'2011 Annul Report Woo~bury (FIN,e~L) do~ I 1-3 sw_wnossssis2 3M MN04998492 33337799..00000099 I 1I Soper 1,201 38 nt Barr Wel 1 sered September 14, 201i: 3M returned Barrier Well B-2 to service and increased 1 pmaata pumping of B-3. I Spentr 14,2011 nied sly sling of Bare Welk 2 Be September 14, 2011: Initiated weekly sampling ofBarrier Wells B-2 and B-4 and 1 wey sulin ofl sein nl nd itor el bi-weekly sampling of select sentinel wells and monitor wells. 1I + Sptmber 26, 2011 3M and WESTON mt with MPCA to vi sty September 28, 2011: 3M and WESTON met with MPCA to review quarterly I emp at sampling data. I1 + pont 30,201 30th Cy Ft re MOH MEA September 30, 2011: 3M met with the City of Cottage Grove, MDH and MPCA. I ett ses OIC 1 SeSpetpetemmbbeerr 3300,, 22001111: : MMPPCCAA iinniittiiaatteedd aa rreessiiddeennttiiaall wweellll saammppllinng evveenntt.. 33MM collected split samples with MPCA. :I seiscoi nd colt od 1 + October 12,2011 3M and WESTON met with MPCAto present information on October 12, 2011" 3M and WESTON met with MPCA to present information on activities completed and data collected to date. I * OOccttoobbeerr 1177,,22001111:: PPllaannnneedd ttrraannsseeccttss ffoorr sseeiissmmiicc ssuurrvveeyy ssuubbmmiitttteedd bbyy 33MM ttoo tthhee 1 MMPPCCAA.. I One 20, 201, A 3M. pln to cond a lial Rett (50) October 20, 2011: A 3M plan to conduct an Electrical Resistivity (ER) 1 Sorta vy stent NPG. geophysical survey was submitted to MPCA. II + Ouiber 21,201: 3M ied PCA coanr tepprl sues October 21, 2011: 3M received MPCA concurrence on the geophysical surveys. I * OOccttoobbeerr 2244--2288,, 22001111:: EERR ggeeoopphhyyssiiccaall ssuurrvveeyy wwaass ppeerrffoorrmmeedd aanndd 22"TMd aannnnuuaall onder sain was promed Genvnc mes w sit win groundwater sampling was performed. Groundwater samples were split with 1 sem NC ---- MPCA's contractor, West Central Environmental Consultants. I + November 3, 2011 3M snd WESTON met with MPCA fn review wei 1 weekly PFC sampling data November 3, 2011: 3M and WESTON met with MPCA to review weekly/biI weekly PFC sampling data. I I I Iyg TTT I ]-4 ST 3M MN04998493 33337799..00001100 sill) 7 yg IVS yHER] o43|78w69 oT) peSS son . I 2 NRE LP) RE SE = 2 I Td \ (N IT x pendJ HWNe--rgh4 = S22 i yl LCs 7 RF MN !1 =)a B= ! I 1 "ER i I mags . MW-4. Ae A San 30 er N(0Fe3 S 05 JS' $l Fey n fF s00o58sP0oC0| east & ~EER aa ee ho 5 IRIAN AV I 1b I aCH' oaSWnB:e0s 3 h 2 EERE mr SENG i(su i I ERBOUNDARY 229 oo ei?("ClAeLEd IbsoSNN lillRe OAakfd ~MW-6 D8 | Es 2a 325 s dfl \ MW-6L ,-- 11 III 0of N I0NEE eS S eRmoseOnal]IE T laeuRNS ? i . 8 II 2.5 11 CTE 1 NY (5 1 1 I) / ' WN >A N ~A I RY) el Yi Legend: 1 ie a e I VERRAN ~ ,~ 'III ~ E2= wnamo ....... Monitoring Well Locations Sentinel Well Locations Barrier Well Locations Approximate Woodbury Site Boundary we Teer wz "PR 4082~7 | AL 3 QUA [I 4123.7.1 WET Figure 1-1 WOODBURY WELL LOCATION AND TOPOGRAPHIC MAP H 3M WOOOTDBT URI Y SE ITE WOODBURY, MN 1-5 3M MN04998494 33337799..00001111 I11I we 1 22.. SSAAMMPPLLIINNGG PPRROOGGRRAAMM I 2.1 GROUNDWATER SAMPLING PLAN I As identified in the Groundwater Sampling Plan and based on subsequent MPCA I 1 `ccoommmmeennttss,, tthhee ggrroouunnddwwaatteerr mmoonniittoorriinngg nneettwwoorrkk aatt tthhee W Wooooddbbuurryy ssiittee FFiigguurree 22--11 ccoonnsissitssts. of 42 monitor and sentinel wells, and four Barrier Wells. As shown in Table 2-1, 19 1 m`moonniittoorr,, sseennttiinneell aanndd BBaarrrriieerr W Welelllss aarree ssaammpplleedd ffoorr PPFFCCss aatt tthhee W Wooooddbbuurryy ssiittee oonn aa I re os nh ees sets we copie Thos wets tse MC. quarterly basis until response actions are complete. These wells include the MPCA 1 etd moi wk msn ih ten rion pein requested monitoring network associated with 3M's request for reduction in pumping and I Barrier Wells B-1, B-2, B-3 and B-4. Depth-to-groundwater measurements are recorded 1 eroels nd Te 1. dn ome lo monthly at the wells indicated in Table 2-1. Annual long-term groundwater sampling is I ccoonndduucctteedd aatt tthhee 2244 wweellllss iiddeennttiiffiieedd iinn tthhee RRDD//RRAA PPllaann ((ii..ee.. iiddeennttiiffiieedd bbyy ""RRDD/iRRAA"" iinn 1 TTaabbllee 22--11)).. AAllssoo,, aann aannnnuuaall PPFFCC ssaammppllee ((iiddeennttiiffiieedd aass CCM MWW)) iiss ccoolllleecctteedd ffrroomm tthhee I conveyance line at a point where flow from the Barrier Wells has been combined. The 1 tons nrg hewn te Wolo se sho ng21. (Te groundwater monitoring well network at the Woodbury site is shown in Figure 2-1. (The I Sees oe eee Co st Cre Ge Sit en conveyance line sample point (CMW) is located at the Cottage Grove Facility and is not I shown on Figure 2-1 ). 2.2 GROUNDWATER SAMPLING EVENTS I1 sampling round was performed in October 2010 and a quarterly sampling round was Prior to reduction in the Barrier Well pumping rates, the first annual groundwater sampling round was performed in October 2010 and a quarterly sampling round was I ered Fda 201. Th ston rd i en performed in February 2011. The next two quarterly groundwater sampling rounds were I 1 `ppeerrfoformrmeedd iinn M Maayy 22001111aannddAAuugguusstt 22001111 aafftteerr BBaarrrriieerr W Weellll ppuummppiinngg rraatteess wweerree rreedduucceedd ((TTaabbllee 22:-22)).. FFoorr tthhee OOccttoobbeerr 22001100 aannnnuuaall ssaammpplliinngg eevveenntt,, ggrroouunnddwwaatteerr ssaammpplleess wweerree I 1 ccoolllleecctteedd ffrroomm 1133 sseennttiinneell wweellllss,, 88 mmoonniittoorr wweellllss,, oonnee ffoorrmmeerr rreessiiddeennttiiaall wweellll,, aanndd ffoouurr Barrier Wells. In the February, May and August 2011 quarterly sampling events, I fame nl Granda sles ve le ori Vl 1 ggrroouunnddwwaatteerr ssaammpplleess wweerree ccoolllleecctteedd ffrroomm 66 sseennttiinneell wweellllss,, 77 mmoonniittoorr wweellllss,, aanndd oonnee former residential well. Groundwater samples were collected at all four Barrier Wells in I 1 OOccttoobbeerr 22001100 aanndd FFeebbrruuaarryy 22001111,, aanndd tthhee tthhrreeee ooppeerraattiinngg BBaarrrriieerr WWeellllss ((BB--1I,, BB--33,, aanndd BB-- 4) in May and August 2011. 1I 1I SA 3M MN04998495 33337799..00001122 Ii1 resto 1 GGrroouunnddwwaatteerr ssaammpplleess wweerree ccoolllleecctteedd ffoorr aannaallyysseess ooff tthhrreeee PPFFCC ccoommppoouunnddss I +30 FOR ing he ote 01 et errs 1 sont, Pr MPC 1 ppeerrfflluuoorroobbuuttaannooiicc aacciidd ((PPFFBBAA)),, ppeerrfflluuoorrooooccttaannec ssuullffoonnaattee ((PPFFOOSS)),, aanndd ppeerrfflluuoorrooooccttaannooiicc acid (PFOA) during the October 2010 and February 2011 sampling rounds. Per MPCA 1 rreeqquueesstt,, ppeerrfflluuoorroohheexxaannoo~icc aacciidd ((PPFFHHSS)) wwaass aaddddeedd ttoo tthhee lliisstt ooff PPFFCC ccoommppoouunnddss dduurriinngg. I rm ey Fh, ig et a a Sif FP wes wt the May 2011, sampling round and perfluorobutane sulfonate (PFBS) was added per 1I Caron rtArg01 sempin tm ering ts MPCA's request for the August 2011 sampling round and subsequent sampling rounds. Following the August 2011 sampling, additional groundwater sampling was performed at 1 elt wells afer PFOA and PROS were eceed during the Mey andor August 2011 select wells after PFOA and PFOS were detected during the May and/or August 2011 I sampling rounds in southern sentinel wells S01JS, S01PC, S02DR, S02JS and S02PC. 1 on Spies 4, 2001, 4 ll FCA o stint te On September 14, 2011, 3M notified MPCA of the aforementioned analytical results, I et. pp a ee ere returned barrier well B-2 to service and increased the pumping rate at B-3. Weekly sampling of B-2 and B-4 was initiated by 3M on September 14 and bi-weekly sampling I soo nSpe t 02 8 mel STARTS, STIR Ed was initiated on September 20-21, 2011 at wells SO 1PC/JS, S02DR/PC/JS, MW-6LR and 1 Se Tin Sn Age 3 tt oun fo ton oo HE MW-12. The September 20-21, 2011 results confirmed the detections and MPCA I requested that the following six wells be sampled in addition to the seven wells 1 pry i SRC SORES, SRA dA. Tonos we previously sampled: S03PC/JS, SO4SP/PC, MW-10 and MW-G. These wells were I re Avan ene at a AT 1 et sampled on October 4, 2011 and again as part of the October 24 28, 2011 annual 1 amplig ound (cpt M10 was aly sale ung he Ose 201 sampling sampling round (except MW-10 was only sampled during the October 4, 2011 sampling I ro CA cp. round) per MPCA staff request. I The sampling locations and dates are presented in Table 2-2. I 1 I 1 1I 1I 1I 1.I I oases 3M MN04998496 33337799..00001133 I|N|RyE.EbeT| 7 i EH ' hia I | ER I1 Eb 4 I I 1 | Lo I Xo 1 ; I 1 1 l= 1I | [read LN) Ll CRE ig Bl " 1: I Let 1I o] LR Co GE TE eA La ww [oo] I ] | | | ye 2 I | i] L|o] fo] [i] fo) I 1 EEN] 1 | I m II111I a LJ:g bsies) Legend: 1 ice Monitoring Well Locations I Sentinel Well Locations 3 Se Barrier Well Locations Bm Approximate Disposal Area I 1 Beds Boundades I| ZZ ette--r Site Boundary os Lo] A] p by _-- N Sct ARE o ! T 500 1,000 ~Feet ~2-3 [eaAnmeum---------- A | : G =igeates a| FIGURE 2-1 crouowater MOMNOINGTIRTOOORRUIINNNDGGWNNAEETTTEWWROORRKK 33MM WWOOOODDBBUURRYYSSIITTEE E33 * WOODBURY, MN aM nosssaso7 3M MN04998497 33337799..00001144 I1I WoodburySite GrToTauabnbldlweea22t--e11rMonitoringPian Woodbury Site Groundwater Monitoring Plan I1 Woodbu3ry Woodbury, MN I 1 DDopetpithni-too-- T optic Depth-to- Gromer Rana or | coundwir| rc | ratonttor Groundwater PFC Rationale for Groundwater PFC I foun in|org | "Somer Jun ee| ole, | "ame Well ID Measurement Sample Sampling Well IDI Measurement Sample Rationale for Sampling I TNTS 82 x Boo eo ome imax E-- B-3 I wi an | momme Jans] x |ax |wwe| B-4 Xu) oA | Q,A Q,A romamae RD/RA RAP RD/RA RAP Foe] MW-H MW-J xX X | Q,A | BWPRP(3) RD/RA RD/RA RAP MW-K X Q,A RD/RA RAP S01JS X Q,A BWPRP(3) RD/RA MW-1 B i[swa 5 | on | owwrmomme fS ame ax sa | worn MW-2 X I is |x Keone oa] own MW-3 X [va | aa| ewmereom [sarc xaa | swmoona MW-4L x I [i a ofa |x| | eet| MW-4 X I wel xT me fume x a | researc MW-5 X foe I wore Lsweo |x| a om| MW-6 X 1 ~ owen fsouse| x | a |mom] MW-6LR x I Fa -- ee Ses x : Fy MW-7 X wT -- FS SY MW-8 X 1 [r= mee |x A noma MW-9 X I [wr| = Sous |x MW-10 X MW-11 x be ---- MW-12 X 1I ox | ownne | sosE|B x A "oma MW-B NA S01 PC X Q,A BWPRP(3) RD/RA RAP S02DR X RAP S02JS X Q,A BWPRP(~) RD/RA S02PC X BWPRP(3) S03JS X RAP S03PC X Q BWPRP(3) S04PC X Q BWPRP(3) S04SP X RAP S05JS X RAP S05PC X S05SP X S06JS X RAP SO6PC X Q BWPRP(3) S07JS X S07PC X Q,A Q,A Q,A Q,A Q Q A A A A A Q A BWPRP(3) RD/RA BWPRP(3) RD/RA BWPRP(3) RD/RA BWPRP(3) RD/RA Per MPCA Request Per MPCA Request RD/RA RDIRA RD/RA RD/RA RDIRA RD/RA WR-03 X ws| - TT a WR-04 I ns ---- sows| xa WR-13 pf me eons |x Gx WR-5828 nie |x - -- CT WR-08 x I MW-F X jb Alem | MW-G x Q,A BWPRP(3) RD/RA, RAP S07SP X RAP S08JS X RAP S08PC X RAP S09JS X CMW(4) N/A A RD/RA A A A Q, A A I LT(~) - A Depth-to~roundwater measurement will be recorded if pump is not operating. ee ------------------ t=). This well was plugged and abandoned prior to excava#on activities in the fo~mer Northeast Disposal Area. |JR rims ~) - Well proposed for sampling under the Barrie" Well Pumping Reduction Plan, submitled to MPCA in March 2010 or added per subsequent MPCA comments. I = Competent (4) _ Conveyance line sample location for combined flow. RD/RA "roma RD/RA noraRDtRA suman BWPRP(3) RD/RA NA- Not accessible, obstruction in well 1 0 ronan sane i conSmhtet qty ba etepropswdanon PFO,FOS, FEA, PFS andPES. Q - Groundwater samples will be collected ffern these walls on a quarterly basis until response actions are complete and analyzed for PFOA, PFOS, PFBA, PFHS and PFBS. mae ie ches mh etd ve Se hott ee A - Greundwat~r samples will be collected from these wells on an annual basis al~er completion of response action for 13 PFCs during the 1st and 2nd annual event and may be reduced thereafter. I rn warty RD/RA - Well proposed for annual long-term monitoring in the RD/RA Plan. j I ee RAP - Remedial ActJos Plan I |}I 29-"4 Z:kFOLDERS 0-g~3M-Woodbury~,WESTON-REPORTS~Oll-Ann~JaI-Report\Tables\Table 2-1 GW_Samplmg_Plan - Woodbury awwnosessise 3M MN04998498 33337799..00001155 I1 i= Table 2-2 I SSuummmmaarryyooff GGrroouunnddwwaatteerr PPFFCC SSaammpplliinngg EEvveennttss SSiinnccee OOccttoobbeerr 22001100 Woudoury Site Woodbury Site 1 Sobor Woodbury, MN II I wowmmwmen Start Date of Sampling Event I [ions[ris[swore[ova[mr]owas[sons|ve[ror [vr sos[oma B-1 o X e X SXerXe e X T 1 eeB-2 TXoT X 1 Tc X X xX oeX PoXeTe X TxX TxX ] I eT B-3 X X e X e X 11 1 1 1 TT X eBe-4 X X X X sXe sXePe X Te X x X xX c] 1 wMwW-e2 T X T X T X T X TT1 1 1 1 TT X 1 I PrMWe-4eL T X T X T X X TT xX e PoMwW-e4 To X TX TX TxX 117 7 TxX To] 1 EoMnW-s6 To X TX Tc X ToX TT X PaMvWe-6L IX TXT TT TTTT "TTT 1" I PeMwWe-6LeR 1 c X X X e X x X xX Po MWs -10 TT 1 TTTTT X TT PoMwW-1e2 XTxX xX xX xX TTX TT1xX TxX | I foeWmRo-0s3 To X TX TxX TxX 11 111 1xX T 1 [wMWo-G IX TT 1 TTTTT X TTxX T 1 1 oeMW-H X SX TX X xX e I [eSo01JsS ToX ToX TX TX Te X TeX xXe xX] [oSe01PsC ToX TxX TxX TxX TTX TTX TT 1 xX TxX | 1 [eSo02DnR T X xX TxX xX TTX TTX TTT-xX1T xX | I FeS0m2JsS To X TX TX TX TT X TT X TTTX TxX | [seS0r2PeC | X TxX TxX xX [TxX TxX [TxX TxX | 1 [sSo03JsS TT 1 TTTTxX TTTxX TxX | I [eSe03PeC LTTT TTX TxX xX [sSo04ePC |>X TTTTTTTT X 1 1xX 1 1 1 [oSs04eSP T X TT 11TT X TTTx X T 1 feSo05JsS > X TT TT X I fseSs05ePCc T X 1 T 1TTT T TTx X T 1 feeS0s5SP >X TTT xX 1 [eSo06JsS TTTTTTTT 1 11 I foS06c PC T X T T TTTT T T TTx X T 1 feSo07JsS T-- TT TTT T TT TT 1 1 [oSp07PeC TTTTTT TTT X I [sS0o7SeP T T T TTTT T TTX T [eSw08sJS >X TTTTT TTT 1 TxX 11 1[ec S08PC I>X TT 1 x X I [soS0o9JSsT X TX TX TxX [T TTT T "X T 1 CoCMwW T-- TT 1 1 1 TTTT 1 xX 1 1 b I rie CMW - Sampling point for combined groundwater from Woodbury Barrier Wells. I I 1I 252-5 awwnosessioo 3M MN04998499 33337799..00001166 !II EE 1 33.. HHYYDDRRAAUULLIICC EEVVAALLUUAATTIIOONN I i 1 AA RReeqquueesstt ttoo RReedduuccee PPuummppiinngg PPllaann ((PPllaann)) ffoorr tthhee WWooooddbbuurryy ssiittee wwaass ssuubbmmiitttteedd bbyy 33MM 10 the MPCAon March 16, 2010. The objecotfitvhee lan wasfo preserve groundwater I rtoestohuercMesPCinAWoonodMbuarrcyhw1h6i,l2e0s1ti0l.l pTrheveeonbtijencgtigvreouonfdtwhaetPelranpowteanstitaollpyreismepravcetgedrowuintdhwPaFtCe:r 1 compounds from migrating offsite. As stated in the Plan, the Woodbury Barier Well resources in Woodbury while still preventing groundwater potentially impacted with PFC compounds from migrating off-site. As stated in the Plan, the Woodbury Barrier Well I ssyysstteemm ccoonnssiissttss ooff ffoouurr ((44)) wweellllss ppuummppiinngg aatt aann aavveerraaggee ccoommbbiinneedd atrate ooff 22.,880000 0to 33,,330000 1 ggaalllloonnss ppeerr mmiinnuuttee ((ggppmm).). AA nnuummbbeerr ooff ssttuuddiieess ttoo eevvaalluuaattee tthhee eeffffeeccttiivveenneessss ooff tthhee ssiittee I Baier Well network have been completed by several diffrent consulans (Bruce Barrier Well network have been completed by several different consultants (Bruce 1 Liesch, Conestoga-Rover&s Assocates, Bar Engineering, and WESTON). All ofthese Liesch, Conestoga-Rovers & Assocaites, Barr Engineering, and WESTON). All of these I studies have reached the same conclusion that the Baier Well network provides an studies have reached the same conclusion that the Barrier Well network provides an I former Main and former Northeast Disposal Areas at th referenced sie from migrating 1 eeffffeeccttiivvee hhyyddrraauulliicc bbaarrrriieerr tthhaatt pprreevveennttss ggrroouunnddwwaatteerr oorriiggiinnaattiinngg iinn tthhee vviicciinniittyy ooff tthhee former Main and former Northeast Disposal Areas at the referenced site from migrating I v0 separate suds performed in May 2007 and May 2008 (WESTON, 2007, 2008) 1 ooffffs-istitee.. TThhee ppeerrffoorrmmaanncceeoofftthhee BBaarrrriieerr WWeellll ssyysstteemm wwaass eevvaalluuaatteedd bbyy W WEESSTTOONN dduurriinngg two separate studies performed in May 2007 and May 2008 (WESTON, 2007, 2008). 1 TThheessee ssttuuddiieess ccoommbbiinneedd wwiitthh ccaallccuullaattiioonnss pprroovviiddeedd iinn tthhee Pl~hha~m ddeetteerrmmiinneedd tthhaatt tthhee I Barrier Well system was capuring potently impacted groundveter and that the Baier Barrier Well system was capturing potentially impacted groundwater and that the Barrier 1 Wells flow ats coudbe reduced and stil maintain groundwater capture. The reuls of Wells flow rates could be reduced and still maintain groundwater capture. The results of I he WESTON evaluation were submited to MPCA i the March 2010 Plan. The MPCA the WESTON evaluation were submitted to MPCA in the March 2010 Plan. The MPCA I 30,2010. Responses 0 the June 30, 2010 comments were adesed i a January 12, 1 aapppprroovveedd aa pphhaasseedd iimmpplleemmeennttaattiioonn ooff tthhee PPllaann wwiitthh ccoommmmeennttss iinn aa lleetttteerr ttoo 33MM oonn JJuunnee 30, 2010. Responses to the June 30, 2010 comments were addressed in a January 12, I chatonimgpleemesnt the Baier Well pumping reduction program. 1 22001111 lleetttteerr ffrroomm 33MM ttoo MMPPCCAA,, ffoolllloowwiinngg tthhee ccoommpplelettiioonn ooff sseevveerraall iinnffrraassttrruuccttuurree changes to implement the Barrier Well pumping reduction program. I1 The ital ruionn pumvpasiinngd on March 11,2011 when Bair Well B2 wasThe was fumed off and initial reduction turned off and the flow rate at Bair Well B-3 was decreased. The overall in pumping was initiated on March 11,2011 when Barrier Well B-2 the flow rate at Barrier Well B-3 was decreased. The overall 1I rtcion in pumpin amore dese of aprosimacly 17 gm, ox 5.3 psn. Flow rates for the Barrier Wells are recorded during the groundwater sampling rounds reduction in pumping amounted to a decrease of approximately 175 gpm, or 5.8 percent. Flow rates for the Barrier Wells are recorded during the groundwater sampling rounds 1I nde loreondedclic by 3prod sytem. and are also recorded electronically by 3M production systems. 1 AAss ppaarrtt ooff M MPPCCAA''ss aapppprroovvaall ooff 33MM''ss RReeqquueesstt ttoo RReedduuccee PPuummppiinngg PPllaann,, MMPPCCAA I1III requested that the following asksbecompleTtie: requested that the following tasks be completed: M3M_MNMDN40s4S99E8S50000 33337799..00001177 1II Si wel MO, MW a NW be ie,1 [] MlooggneitdortiongdewteerlmlsinMe Wwh-e4t,heMrWth-e4LopeanndinMeW rv-a6sLofbethgesaemwmeal,lscailnitpeerrs,ectantdhevhidiegoh logged to determine whether the open intervals of these wells intersect the high I trraannssmmisisssiivvtityyzzoonnee ((HHTTZZ)) oofftthhee PPrraaririiee dduu CChhiieenn GGrroouupp;; I 1 + Transducers be installed in several wels of ners to continually record ter eTvrealnsrdeuscpeornssebse tioncsthaalnlegdesininspevuemrpailnwgerlelss.of interest to continually record water level responses to changes in pumping rates. I1 sestions. 1 `TThhee aaccttiioonnss ppeerrffoorrmmeedd bbyy 33MM iinn rreessppoonnssee ttoo tthheessee rreeqquueessttss aarree pprroovviiddeedd iinn tthhee ffoolllloowwiinngg I sections. 1 33.11 MMOODDIIFFIICCAATTIIOONN OOFF MMOONNIITTOORRIINNGG WWEELLLL MMWW-6-6LL. I PPrriioorr ttoo tthhee ppeerrffoorrmmaannccee ooff tthhee bboorrechhoolle ggeeoopphhyyssicisacatst tthhee mmoonniittoorriinngg wweelllss rreeqquueesstteedd bbyy 1 MMPPCCAA,, sseeddiimmeenntt tthhaatt hhaadd aaccccuummuullaatteedd iinn tthhee ooppeenn bboorrcehhoollee ooff mmoonniittoorriinngg wweellll MMWW--66LL I hhaadd 0to bbee rreemmoovveedd.. IInn JJaannuuaarryy 22001111,, aann aatttteemmpptt ttoo rreeddriilll tthhiiss wweellll aanndd rreemmoovvee tthhee 1 sseeddiimmeenntt wwaass mmaaddee uussiinngg aann aaiirr rroottaarryy ddrriilllliinngg rriigg; hhoowweevveerr,, sseeddiimmeenntt ffrroomm tthhee oovveerrllyyiinngg I lacial drif unit continued to accumulate in th open borehole section (231 to 320 feet glacial drift unit continued to accumulate in the open borehole section (231 to 320 feet 1 bbeellooww ggrroouunndd ssuurrffaaccee ((fft bbggss))))oofftthhee wweellll iinnddiiccaattiinngg tthhaatt tthhee oouutteerr ggrroouutt sseeaall ooff tthhiiss wweellll I wwaass nnoo lloonnggeerr iinnttaacctt. DDuuee ttoo tthhee ddaammaaggeedd sclseal, hthiiss wweellll nneeeeddeedd to bbee rreeccoonnssttiittuutteedd,, aanndd aa 1 roottoossoonniicc ddrriilllliinngg rriigg wwaass mmoobbililiizzeedd ttootthhee ssiittee oonnccee ggrroouunndd ssuurrffaaccee ccoonnddiittiioonnss iimmpprroovveedd I iinn AAppririll 22001111.. TThhee rroottoossoonniicc rriigg iiss ccaappaabblleeooff aaddvvaanncciinngg oouulteerr ccaassiinngg dduurriinngg ddrriilllliinngg ttoo 1 pprreevveenntt sseeddiimmeenntt ffrroomm eenntteerriinngg iinntootthheooppeennbboorrcehhoollee sseeccttiioonn oofftthhee wwelell,l. I 1 Using Using the the rotosonic rotosonic rig rig, tthhe wweellll wwaass oovveerrddrriillleedd ttoo rreemmoovvee tthhee oouutteerr sstteeeell ccaassiinngg.. TThhee I wweelll wwaass tthheenn rreeddrrilllledd aanndd tthhee rroottoossoonniicc riigg wwaass ssuucccceessssffuull iinn rreemmoovviinngg aallll sseeddiimmeenntt 1 ffrroomm tthhee ooppeenn bboorreehhoollee.. AAfftteerr tthhee sseeddiimmeenntt wwaass rreemmoovveedd eanndd tthhee bboorrechhoolle ddrriilllleedd ttoo tthhee I pprreevviioouuss ddeepptthh ooff ccoommplpelettiioonn,, tthhee rroottoossoonniicc ddrriillll ccaassiinngg wwaass rreettrraacctteedd ttoo aa ddeepptthh wwhheerree 1 bboorreehhoollee ccoollllaappssee wwaass nnoott aa riisskk.. BBoorrcehhoollee ggeeoopphhyyssiiccss wweerree tthheenn rruunn iinn tthhee wweellll wwhhiillee the i the orottoossoonniic igwas rig was st set over over the the bboorrcehhaollee.. AAffteerr ccoommpplleettiioonn oofttfhhe bboorreehhoollee ggeeoopphhyyssiiccss,, 1 the wel was renamed (MW-GLR) anda 2-inch screen (280 0 320 bgs) and riser were the well was renamed (MW-6LR) and a 2-inch screen (280 to 320 ft bgs) and riser were I ppllaacceedd wwiitthhiinn tthhee ffoorrmmeerr ooppeenn bboorrcehhoollee iinntteerrvvaall ooff tthhee wweell.l. TThhee ssccrreeeenneedd iinntteerrvvaall wwaass 1 ttaarrggeetteedd ttoo mmoonniittoorr tthhee mmiiddddllee oofftthhee rari Prairie ddsu CChhiicenn ffoorrmmaattiioonn,, wwhhiicchh iis bbeelliieevveedd oto bbee I tthhee HHTTZZ ooff tthhiiss ffoorrmmaattiioonn.. TThhee rreeddrriilllliinngg aanndd mmoodidfifiiccaattiioonnss ttoo tthhiiss wweellllwweerreeccoommplpeletteedd .I rss Z:V::OLD E RS.0-9~3 M~WoodburykWESYON-R EPOI~TS~2011-Ann ~l-Repo{~2.011 Amual Report W~dbury (FINALI.d~ I 3-2 M3M_MNMON409499988550011 33337799..00001188 II1 ne a ped NOH poet wel prs ie si sis a under an approved MDH reconstruction well permit using the existing unique well 1 mr (MDI ID No. 520057 number (MDH ID No. 520037). II 32 soReHoLE GEOPHYSICS 3.2 BOREHOLE GEOPHYSICS I Th ste of bret spy (gaan, cle ad id ging) seid by The suite of borehole geophysics (gamma, caliper and video logging) requested by 1 MPCA wer competed in monoring wel VAL sd MW LR in fen sd Ape MPCA were completed in monitoring wells MW-4L and MW-6LR in January and April I 22001111,, rreessppeeccttiivveellyy.. MMoonintitoorriinngg wweellll MMWW--44 iiss ssccrreeeenneedd ffrroomm 9933 ttoo 112288 fftl bbggss aaccrroossss tthhee 1 1. Per Sandan nd spe Pre Chin Gop. Thi depth o lo St. Peter Sandstone and upper Prairie du Chien Group. This depth is too shallow to I eethetHITZ ns the milofeoe Pri ds Chin rou, bor physics intersect the HTZ near the middle of the Prairie du Chien Group, so borehole geophysics 1 could nb eformea is cain do 0 eld consis. The gop nd could not be performed at this location, due to field constraints. The geophysical and I Vie npeton logs fo manor cls MAL ad MW-LR, re shld video inspection logs for monitoring wells MW-4L and MW-6LR are included in 1 Atocments Attachment A. I 1 T`Thhee ffoolllloowwiinngg oobbsseerrvvaattiioonnss//iinntteerrpprreettaattiioonnssccaannbbee mmaaddeebbaasseeddoonntthhee bboorreehhoollee ggeeoopphhyyssiiccss I etorned in x mora cl performed in each monitor well: 1 + Monoent vt, Monitoring well MW-4L I1 o The ich se casing in is wel exnds 0122 1 gs, snd gro The 4-inch steel casing in this well extends to 122 ft bgs, and grout I nie 1242 bg extends to 124.2 ft bgs; 1 o Th ol epthof he wel vas essed a 1571 Rb o The total depth of the well was measured at 187.1 ffbgs; 1I o The caer los rv aes in bore diet prs 3 The caliper logs reveal increases in borehole diameter present at I oom 124,156,152, 175, a 15 vg approximately 124, 136, 152, 175, and 185 ft bgs; 1 o The iden pein og showed wren Towing fom Higher in The video inspection log showed water/sediment flowing from higher in I he ele io he ctr preset at 152 bg. The care at i the borehole into the fracture present at 152 ft bgs. The fracture at this 1 ethspend bebop sci with edge depth appeared to be horizontal, possibly associated with a bedding plane. I Flow hv ars ts sont Hcl due fo the amin of sey Flow observed across this zone is likely due to the pumping of nearby I1 Buen Barrier Well B-3. I ,I I mosses 3M MN04998502 33337799..00001199 i ! Monitoring well MW-6LR 1 The The depth depth that that the the borehole borehole ggeeoopphhyyssiiccss aanndd vviiddeeoo llooggggiinngg ccoouulldd bbee i pend i is wll us kd a fo beholder 1 Kimi the risk of borehole collapse, the dil stem was advanced to performed in this well was limited due to borehole integrity. In order to limit the risk of borehole collapse, the drill stem was advanced to I peimatdy 271s. Thelr he pe borehole of te wel hi approximately 278 fl bgs. Therefore, the open borehole of the well that 1 mgd ing sol gyi vi fn 7510321 15 was logged using borehole geophysics was from 278 to 321 fi bgs; 1I o Thal dptfthe well wis ess321 bs o The total depth ofthe well was measured at 321 ft bgs; I The clr log denied dpi cre ove fom 2010250 1 ves o The caliper log identified a significant fracture zone from 280 to 290 fi bgs; 1i o Th vio og was ccs de 0 ih iy of i ver vii The video log was inconclusive due to high turbidity of the water within I oboe th mtd ily dh iy to vrs the the borehole that limited visibility and the inability to advance the 1 donb camapus 25 kgs downhole camera past 286 ft bgs; I Ae coin he bool gcphyss, he di shined wr opr the After completion of the borehole geophysics, these data obtained were compared to the 1 iofs or cach mitcig wel. condi iho ps formonring lithologic logs for each monitoring well. According to the lithologic logs for monitoring I MWA thf the Fi Chic as nda 10. bys. The Hilo well MW-4L, the top of the Prairie du Chien was noted at 110 ft bgs. The lithologic log 1 for monitor ll MYL indiid a sp foe re du Cin rp vis for monitoring well MW-6L indicated that the top of the Prairie du Chien Group was I rms psi 25 1 bps. Te ls sie ot hicks of encountered at approximately 225 ft bgs. The logs indicate that the thickness of the ] Pre du Chen Gr in monn vel MVAL ad MV.L vas Prairie du Chien Group in monitoring well MW-4L and MW-6L varies from I omy 16510305 ok eget. Te Pid Chin Gr fs iol approximately 165 to 205 feet respectively. The Prairie du Chien Group is divided into 1 espe Sop nd oe Ons lie. Phd ese ft bi the upper Shakopee unit and lower Oneota dolomite. Published references indicate that I TZ vith ideo he red hen Gro ee cont betwee he the HTZ is within the middle of the Prairie du Chien Group near the contact between the 1 Shops dOnt. From ts fmt be TZ ricboe 190 Shakopee and Oneota dolomite. From this information the HTZ is projected to be at 190 I ffttbbggss iinn MMWW--44LL aanndd 332255ffti bbggssiinn MMWW-6-6LLRR.. iI Hou commun betwee lo Ske ty Tock Hydraulic communication between the shallow Shakopee and underlying HTZ can occur 1 ugh veri cin iin per Pred Chie Gro Topo 2006 through vertical fracturing within the upper Prairie du Chien Group (Tipping et al, 2006). I Thi te ey mechs for To ord he our end a 152 bs in This is the likely mechanism for flow observed in the fracture identified at 152 ft bgs in 1 oii el MAL. Whe hs fetes hove he. spect det of te HZ. monitoring well MW-4L. While this fracture is above the expected depth of the HTZ, I ow hui ei gion fo hs deh cust heen che the flow observed in the video inspection log at this depth indicate that the open borehole I ! awnozs 3M MN04998503 33337799..00002200 1I 1I son of onion wll VAL i in tli ton ith ey flo section of monitoring well MW-4L is in hydraulic commtmication with a primary flow 1 AA A zone supplying groundwater to the Barrier Well network. In addition, during the Barrier I `WWeellll sshhuutt ddoowwnn tteessttss ppeerrffoorrmmeedd aatt tthhee ssiittee iinn MMaayy 22000077 aanndd MMaayy 22000088,, tthhee ggrroouunnddwwaatteerr 1 vio in mont el ANAL is os comps oss oti cle elevation in monitoring well MW-4L is lower compared to adjacent monitoring wells I tTTmt Tiss An Tae MW-4 and S09JS under pumping conditions. This data, in combination with the data 1 ole durin he bho gop progr, ni prt flow ste he collected during the borehole geophysics program, indicate preferential flow across the I zzoonnee mmoonniittoorreedd bbyy tthhee ooppeenn bboorreehhoollee sseeccttiioonn ooff mmoonnititoorriinngg wweellll MMWW-4-4LL.. SSppeeccififiiccaallllyy,, 1 Bes i a Se TE A So flow occurs upward from the tmderlying Jordan Sandstone and downward t~om the I lo Pte fn Cen i et of pe ech in of ning shallow Prairie du Chien unit into a portion of the open borehole section of monitoring I aL well MW-4L. I At monitoring well MW-6LR, the highly fractured zone identified at 280 to 290 ft bgs is approximately 55 feet below the top of the Prairie du Chien Group. This zone is at a I ddeepptthh lliikkeellyy iinntteerrcceeppttiinngg tthhee uuppppeerr ppoorrttiioonn ooff tthhee HHTTZZ wwiitthhiinn tthhee PPrraaiirriiee dduu CChhiieenn.. 1 a Tree to Ta ee However, the depth where different geologic units (e.g. St. Peter Sandstone and Prairie I du Chien) are present at monitoring well MW-6LR indicate a vertical offset compared to 1 i A ---------------- other areas. A geologic cross-section was constructed to aid in visualizing the subsurface I logs onion ity at ning walls WL ad MAL (ioe geologic conditions in the vicinity of monitoring wells MW-6LR and MW-4L (see Figure 1 1 or ert of te csi, esto vee is do+ 3-1 for the location of the cross-section). The cross-section was constructed along a I ead ss v6 we vo vera mos oe Wo north-south transect along the western site property boundary using lithologic 1 tomato cles dn dio sci. soon in Fie 32,0 5. ee information collected during drilling activities. As shown in Figure 3-2, the St. Peter I A ASI Sandstone and Prairie du Chien Group are interpreted to be vertically displaced 1 FR downward at monitoring well MW-6LR. Therefore, MW-6LR is not in direct hydraulic I 1 ccoommmmunuincicaattiioonn wwiitthh ootthheerr aarreeaass ooff tthhee ssiittee dduuee ttoo tthhee vveerrttiiccaall ddiissppllaacceemmeennttooffggeeoollooggiicc ieunits. 1I A SR i 0 520850 SOT 0 HBR Additional geophysical work is planned in this area to confirm the interpretations I stein eos sin. presented in the cross-section. I1 20 WATERANELUDNTORIS 3.3 WATER LEVEL MONITORING 1 re Rr Fa Hea 38 Sree fe The water level monitoring program for the site consists of monthly manual depth-to.I gente asses woth oie els for Se groundwater measurements recorded at all monitoring wells as shown in Table 2-1. II is I mosses 3M MN04998504 33337799..00002211 1II RCA ted nes ihe ders ll isin of MPCA requested that transducers with the dataloggers be installed in a minimum of four 1 wweellllss ccoommpplleetteedd iinn tthhee JJoorrddaann SSaannddssttoonnee,, PPrraaiirriiee dduu CChhiieenn GGrroouupp,, SStt.. PPeetteerr SSaannddssttoonnee I aanndd ggllaacciiaall ddrriifftt aaqquuiiffeerrss.. ITnn rreessppoonnssee ttoo tthhiiss rreeqquueesstt,, ddaattaallooggggeerrss wweerree iinniittiiaallllyy iinnssttaalllleedd 1 iinn JJaannuuaarryy 22001111 iinn tthhee ffoolllloowwiinngg ssiittee mmoonniittoorriinngg wwelelllss:: I1 bedrock vally west of the ie + MMoonnititoorr wweellll MMWW--HH -scscrreeeenneedd wwiitthhiinn tthhee ggllaacciiaall ddrriifftt sseeddiimmeennttss iinn tthhee bbuurriieedd bedrock valley west of the site; I + FFoorrmmeerr rreessiiddeennttiiaall wweellll WWRRO033 ---ssccrreeeenneedd wwiitthhiinn tthhee JJoorrddaann SSaannddssttoonnee wweessttoofftthhee 1 J-- Barrier Well network; I MMoonnititoorr wweellll MMWW--66 -~ ssccrreeeenneedd wwiitthhiinn tthhee SStt.. PPeetteerr SSaannddssttoonnee ssoouutthh ooff BBaarrrriieerr 1 WelsB,B3, ad Wells B-l, B-3, and B-4; I MMoonniittoorr wweellll MMWW--44LL ~- ssccrreeeenneedd wwiitthhiinn tthhee mmiiddddllee ooff tthhee PPrraaiirriiee dduu CChhiieenn 1 formation cae Baie Well B-1, A transducer was ntl his wel prior o formation near Barrier Well B-1. A transducer was installed in this well prior to I mmoonniittoorr wweellll MMWW--G6LL bbeeiinngg rreeccoonnssttrruucctteedd.. AARfeterr tthhee rree-ddrriilllliinngg aanndd I1 reonsiction ofmoni well NW-SLR, the transducer in mir wll MV.AL 1 was moved tomonitorwell MW-6LR. reconstruction of monitor well MW-6LR, the transducer in monitor well MW-4L was moved to monitor well MW-6LR. I TThhee ffoouurr mmoonniittoorriinngg wweellllss wwhheerree tthhee ddaattaallooggggeerrss aarree iinnssttaalllleedd aarree tthhee cclloosseesstt mmoonintiotorriinngg. I 1 `wweellllss tthhaatt aarree hhyyddrraauulliiccaallllyy ddoowwnnggrraaddiieenntt ooff tthhee ddiissppoossaall aarreeaass.. TThhee ddaattaallooggggeerrss wweerree. pprorgoramgmreadttmoocmcoolellleedcctt wwaatteerr lleevveell ddaattaa aatt 1155--mmiinnuuttee iinntteerrvvaalls.. I I I I I I II mrrm I I3MM_MMNNO044999988550055 33337799..00002222