Contaminantrnigration from disposalof acid tar n'astesin fractured Coal Measuresstrata, southernDerbvshire
D. BANKSI.2,N. L. NESBIT3,T. FIRTH] 4 & S. PowER5'6 I ScottWiison Kirkpatrick, Ba.yheathHouse, RoseHilt West,Chester/ieltl, Derbyshire 540 lJF, UK. 2 Presentadtlress: Norges Geologiske Undersokelse, Postboks 3006-Lacle, N7002 Trondheim,Narwa;y. 3 Aspinvall&Conlpany,lYalford Ma.nor, Baschurch, Shrevvshur),, Shropshire Sy4 2HH,IJK. a Presentaddress: Rendel Geotechnics, 6I Southvt'arkStreet, Southw,ark, LondonSEI lSA, UK. ssection.for EngineeringGeology, Department of Geology,Roya[ Schoolof Mines, Imperial Collegeof Science,Technologl' and Medicine,Prince ConsortRoad, London SW7 2BP, UK. 6Presentaddress: Mott ConnellLtd, l2th Floor, Sun Hung Kai Centre,30Harbour Roat1, Wanchai,Hong Kong
Abntract. In excessof 60000 ml of acidic tai wasLeifrom a lubricating oil facrory havebeen disposedin old clay pits at a siteon Coal Measulesstrata near Belper,southern Derbyshire, UK. A site investigationwa.s carried oul to usses!the nature and volume of lhe waste,lhe extentof contaminantrnigration and possibleremeciiatjon optlons. Thc wastcshavc mig.ratcd as free phase,gravity'driven flows of nerni-fluid tar. Thesetar flows have ied to contamination of on-sitc ponds by hydrocarbon emulsions and dissolved phase contaminanrs.I.imited gronndwatercontamination by dissolvedphase contaminants has also ocrurred.At present. ;ro impact on of-site surfacewater rcccptors has bccn detectedand no risk to any water abstraction has been identified. The site in'estigation has confirn:ed the exceedinglycomplex nature of the Coal Measuressequence. The Coal Mcasuresexhibit some aspectsof a multi- layer aqnifer system, dorninant fracture flow mechanisms. strong anisotropy governed by fracture orienlation ancl a heterr)geneousand discontinuousclis[dbution of groundwater heads.indications of strong vertical head gradients,possibly related to under-drainageby mine workings, weredetected.
{ Introduction consultantsto carry out the investigation.Scott j Wilson Kirkpatrick was cmploycdto manage Thc studysite is iocatednear the town of ,Belper the siteinvestigation and assist in interpretation. : in southernDerbyshirc and comprisesa number The site investigationwas executed by Wimpey of old clay pits in Lower Coal Measuresstrata Environmental Limited, while a geophysical which have been usedIor the clisposalof acid surveywas carried out by the BritishGeological tars -- a waste product fron'r the re-refrningof Survcy. Funding for the project has been pro- usedlubricating oils. Derbyshire Counry Council vided by English Partncrships (forrnerly the (DCC) commissionedan investigationwith the Department of the Environment)through a followingobjectives: DerelictLand Grant. r definethe areaand volumeof thcscpits; r definethe extentto which theyhave contami- natedthe surroundingsoils and groundwater; Objective of thi.spapcr . assessthe potentialfor migrationof contami- The paper provide nation off-site; objectiveof this is not to an in-depthcase analysis of the resulting . recommcndalternativcs for rcmediationof soil ali data anclgroundwater. from the studyof thc tar pits. In particular,the paperdoes not discussdetails of chemicalana- This informationwas required as part of a pro- iyresof contaminatcdsoil, geotechnicalpropcr- posalto redevelopthe site.DCC cornmissioned ties of the site,nor the dctailedhydrochemistry Aspinwall& Companyand a tearnof associated of the groundwaterat the site. Indeed,due to
B.lxrs, D., NEsBrr,N. L.. FrnrH, T. & Powrx, S. 1998.Contarninant migration from disposillof acid tar wastesin fractured Coal Measuressirata, southern Derbyshire.In: Mrtxen, J., BeNrs. D.. Duvplsro^*, S. & Frnvon, M. (cds) Gronnrlryater('.lontarninants and their Migruti rheiirct that therewas no eviscr-lceof sigtriliceintthe srrlvenlexrtact front the tar inc'licareclit tcr ofi'-sitemigration of cclntaminantsin ground- or bc predorninantlycomposecl of components surfarce-wrrter.thc intensiryof hycirochenricalwith a higherboiling point rhan Cr: n-alkane. investigationw?ls not as great as would have Additioniiliy,free, acidic oils areencounrerecl becndesirable tiorn a rcscsrch-orientedstudy. on the site. These may be associatedwith Neverthelcss,the study has provided useful r:xcessiveuse of sulphuricacid in the re-refining inforrnationon lhehydrogeology and. in particu- proccss.but mayzriso bc derivedfrom weathcr- lar. the contaminantflow pathwayswithin the i:rg of the tars. The oii typicallyconsists ol Coal Measuresaquifcr system. lt is this aspect E7o4saiuratcd hydrocarbon with boilingpoinrs on which the paper lbcuses,ahhough it also in the Crs-Cz.iiange, 7Yo aromaticsand 6% aims tr: placesuch inlbrmation in the context polar resin. of the siteas a whole,anci the possibieremedial The Fuller's Earth urarcrialsindicatc the options for clcan-up.To supporr this objecrive cyclohcxane-extractabiematerial a Suppliedby TheBritish Library - "Theworld's knowledge" DISPOSALOF ACID TAR WASIES l5) Tabic|.Anult'tit.ulre.rults|ilr,;oilsundwas|e'sfitutttltn|hcs|ud.i.si|t,',4!!uttit.i m il I igr anrs per k i loerwt Type Supposed'clean'scils Bcntonitcfrompits Whire Coritauriuated lrce {ar nrociuct 'Irir,il acid mudstone Trial pit Trial pit pit Trial pii maierial Tnai pit Trialpit Br:rehole P9 at TP3 at TPIi at TPlTar Borehole TP3l ar TP49at 56 at 2.1rl i .8ir 2.2ni 0.8rn S2 -1.i nr 0.0m j.6 nt pH 7.6 6.8 6.0 ).t i.4 5.8 0.8 3.9 CEM o/o 0.08 0.03 19.6 2.69 2.3'7 12.36 t.77 EC 63.3 4s000 Fe 37200 3470 33 28800 Acid sol. 994 697 56600 35.50i) 22! 000 2030 I 3C000 36400 soi- cl- 63.3 <12.5 71.6 20.3 AI r6500 Mn i7t As 27 8 I (b Phenol 0.6 Cyanide <10 <10 CEM : cyclohcxaneextractairle matier: Phenol,total monohydric phenols;PAH. poiynuclcararomatic hydro- carbons (totai); Min. o.il, total mincral oil; NSO, heicrocyclic polar resins (inciuding nitrogen, sulphur and ox).gen-ccntainingspecies); TEM, toltreneextractable mrrttcr: CV, calorific value{MJ kg-')t PCB, polychlorinaied t biphenyis;EC, eiectricalconductivity (pSc'n- ). arereferred to as tar pits A-H, and thoseto the circulationof air and the removalof coai and eastas tar pits l-4 ancl1A (seeFig. i). spoil(Fig. l). The coalseams that, according to BritishCoal. havebeen worked in theimmcdiate vicinity olthe History of the site siteare summarized in Table2 andshown in Fig. 2. Thereis a possibilitythat unrecordedworkings particularlyat shaliow This area of Dcrbyshire has ireen mined, may existbeiow the -lhinsite, principallyfor coal and clay, for at leastseveral Suppliedby The BritishLibrary - :'Theworld's knowledge" - 286 .J. T]ANKS ET .4L ,YI e I F e o- E F o 6 a I c ee Oe b E L) Rt t) ,o 'l a TS >l F E$ = -b 6 7t J 'H ,l r o lrc - w 6- !! tL Suppliedby TheBritish Library - "Theworld's knowledge" l)lSPOSALOF ACID TArt WASI'IF.S t87 'l'able 2. Worketl<'oul scunu at tl:e studt .sitc Seam Approximatedepth (m) Type ol workings Periodof woikin-e MickleyThin 0 Piilar and stall Up to mid- i950s(e ast of the sitc) (or UpperBrarnpton) Kilburn 75 Lllcertain r830- i 935 Opcncasiimnrediately wesi of site Alton 235 Longwall r9591965 .Bclpcrlawn 265 Longwall 1967 DCC grantedplanning perrnission for various thc tar have been made by adciitionof iime opencastpipc- anclbrick-clay workings from the and ashes,but these appcar to have been materialsoverlying the Morley Muck coal in uns';ccessful. April 1961,The clays were worked down dip East of the trunk road, acid tar disposal usingdragline techniques, leaving sequences of continuedup to August 1977when the County N-S striking high walls.Pcrmission to coniinue Surveyor refuseda licenceto continue tipping clay working after 1980was refuse itl';1 Sb:.i-:'n-y I I 'fi' I i I ':qr., whtki?{t l"d{ai:t. l7n,rr U; .F a.r$1r,1 i(firr, ill:ar1r. {: - 1gl lilusr lC. {,I..r: Atsr ls5dit::, A; sx,r|'; Jmi- ,l:t:l rr^, 9il:;ht Ln' :l):rf,t +lS€. :trtir nJ" Fig. 2. Gcologicalcross-section through the strrclysite, baseci on availablegeologrcal maps. The horizontal scalcis equal to the vertical scalc. Suppliedby The BritishLibrary - "Theworld's knowledge" i). BANKS ET AI,. (a) (b) l'i& 3. Photographsshowing (a) tongueof tar welling up f rom neartar pit 2 anclenrering the middle lagoon(width of flow is around 60 cm) and (b) flow of tar along a fruciurc in Coal Measurcssrrara. phasecontaninants can be seen seeping out of the Surface wctterand ntater abstractions soiiat the sideof thenond. To the westof the trunk road,eight pits were The northern part of the easternboundary of used for tipping between 1972 ano 1976. In Lhcsite is markedby a smalistrcam, which is a 1976,howcver, ihe roadcutting was widened to tributary of the Bottle Brook. The BotrleBrook createa deepercut for the road. This led tc) itsell'fccdsinto the River Derwentjust norrh ot instabilityof thc wesrside of the curtingand, Derby. The Bottle Brook is classiliedby the Donscqueirtly,thesc eight tar pits weredisturbcd. NRA (1991)as a Class2 (fair)watercourse, i.e. A prograilme of rcmediationwas carriedout: it is suitablcfor potablesupply afier advanceci the tar fronr pits B-H seemsto have been trcatmenr,it supportscoarse fisheries, and it rcmored lioin the site, and someof tire tar in may havemocierate arnenity value. pit A was probablyredeposired in pit lA, east No licensedor unlicensedground or surface of thetrunk road,while part wasleft in situ.To water abstractionsarc known to cxist iii the the westof the trunk road and at the northein- immediatevicinity of thc site which might be most cnd of the site,a ferv tar secpsare visiblc consideredto be at risk frorn contaminants in the cxposedrocks. The tar appcarsto have migratingfrom the studysite. moved latcrally from tar pit A aiong fractures in the sandstone(Fig. 3b). . The tai appcarsto be gencrallysolid during Site investigafion thc winter, but, in the 't994.course of site visiti during April and May it was noted that T'hesite investigation was carriedout between rhe tar was becominginore fluici and mcbile Januaryand February 1994.A numberof inves- and beginningto flow, indicatingttrat conrami- ligaiive techniclucswere use Suppliedby TheBritish Library - "Theworld's knowledge" DISPOSALOF ACID TAR IV/TSTES 2S9 (c) (d) ,,,1;'i,;1,;-,r;liifi$i rj.,,;.i.,.,,j.ii-,ii - T: )!: ..i i...i:.1.1 ji1: :ii.r: ::: . i:;i:.i1:;;ii;i Fig. 3, Photographsshowing (c) excavationof tar pit 4 and (d) driliing of an over-u,aterborehole liont a iloating pontoon on the middlc lagoon. a a tcpographicalsurvey, r six over-waterdynamic cone penctration tests a a geophysicalsurvey by the BritishGeological (rniddlelagoon), Survey, o a depth sounding survey of the norih arrd a 44 staticcone penetration tests (CPTs), south lagoons, a 13cable percussivc boreholes, o 34rotary drill-hoies, Thc rotary cored boreholes were iocateC so o 72machine-dug trial pits/trenches. as to obtain a definition of the stratigraphyoi' o oneover-water borehole (middle lagoon), lhe site. Sixteen of tiie rotary boreholes {and Suopliedbv The BritishLibrarv - "Theworld's knowledoe" 290 D. BANKSET .4L. H Z = rEE s /-'' =- | -TEJ 6 A :a Eh = I / ...... =-zZ-=Hu SJ'=s;iH OL ;!i E2E;E:g |,,tii il\ (tl r,ll - rir e soecooc \ll L!= I:I: ]Eo 1" e t!,j r t,r: 5E :)'j o< 'l t\ V,J 'ij !ll it) 'J ir. : tl t'. .\il h ! O ! g b l c) .ola n: crl tl , l-l i l/ | Kta V ' a i6 l I lFl -1 ni A I 6) \-\ \-[ r L tJ vi o A i = a irr lrn i) E bo EE l.ol : l.-l Suppliedby TheBritish Library - "Theworld's knowledge" DISPCISALOF ACID TN R WASTES 19i orle percLlssionborcliole) were installeciwith snmplcsol'groirnclwatei were ilrken into a com- nronitoringrvclls to enablemonitorinq of hydro- binationof piasticarici glass containcrs with geologicalconditions and coilection of grounii- preseivittivesappropriaic to tirc paranteiersoi waiersamples (Fig. 4: Table3). concein.The sampicswere transporteci to the N{ostof therrial pits iFig. - Suppliedby The BritishLibrary - "Theworld's knowledge" 292 D. BANKSI.T AL. i:^^ |> Q a ? tO,rl c.t C O cF.+ - F= ro \C r| \.} \o o -, o c co c{ o - et $ - \c r.- + o !-- .d i o txgS oc c- & tr- ?E t*- r rr € @ r-. !p r_, oo co o, * _x -.;jj 99 ! 3s-i 3=^^ !9 C! a I Q F,., € O c) \O - $ r, F- - rn O ; a€E Fl \O @ € vtf - (-.,l n - r| O\ t6 r} r-. aN - o - o $ \{) c.t f/ \^ c.l - c..t r) < o N F,l 5*ge IT J v) () " *d = == {J<= c A= h o .!.) >, A)- c ll u.E E > ? E =r+ .E t E > > = r.EE i c/2 (A A tn V) (h rh 2 V) cA 0 th Q A O Z ?. 3 rr F. r ol h rr \r't lat |/l h g\ A O d,CNtr| drr.\ J v'l oq q i t.'1..i \ d o. o. J .'t cri r, Q E rit s !'j u? u') ra q d n q ?...| r^ r| o l'-) o {t Fr J d or oc ed ej <-.d -: J +<-i + Q 9 F r'l i r,f.l (\{ c./ s|. a{ N - - rrt - a.t - rO li(nrilltlllt ;- ilq rnotr,ot.rr.a!noora)ratt c)q) or o |\c r.i.jGi .i-o<.ic.iv.ir-cdi;ci;q; Fl an F F) a.r (r.l .t) (+, r.r - - Og O .O rir)r) a-.n r.1 J 'a O lattso\c) €F- \r) q u''l _ r: el q,.i 4., ag o. C -j n od d i cl J.,i q ; OA €, O\ ca, a! $ - f\.1 t .f .ar r| \O t-. cO t** \O (\l F- r (J lF,9si '!nl\Orlr, I I rLr too |'| I | | | r\lhhn I hh I h O\ i.| C F- rar c.l tt a.l €' S !F O C.l oO Fr O t-* A o. € c- ro cj -i + vj r.- +c.j \d 'c! cj t.- c c, S $ \O rar .(i t-- \O \O F- \g f-. € \O a-- F oO - ()q tr a c YF tl talN & L)E r. qq'lqqqqcldc'oQo=roo adv Jo'octdcjdJc.i (t) d7 .il ri oi oi,.ir-i ,rioia \r - v.f Fr.+$ : (\.l - - (\t - r\t _ d\ ! | 0, OA I I I : too I | | | | I I u'l 9 "r c rl q q q \ q v? q q n q e q iiE = Q - n lin. - - O !' € rO - r-. oc r\ r-..1 F, - - (r.l a.i a\ r, ..1 F] rc () !u I 0.) 2 EN vt Or|OOOOninrnc}rarr orl ! =A lrr r) rra r-- C) f7: $ ^l \g .-.t d1 u v2= a'a oo cc, 'tro G'E o; '=t ati Eol j'. AL -t^l - |^ r'i rn + rr \C F- - \O r*- O\ = R - a-o ,F'r'|='F=T.F; c0cao6ccrm@,, U1 ft "The Suppliedby TheBritish Library - world'sknowledge" DISPOSAI OF ACJD TAP. WASTE,S 293 -l-hese beddin-e-paralleljoint set,irnci ihese discontirru- aquifers'seldornproduce large quandtics of itiesocci"rr u'ith reiisonairleregularity across the rvaterlbr abstractions.but arc iniporLani both lbr wholesite. The two melinnon-bcdciing partrilcl locaisuopiies anri in supplyingbaseflow for iivers. joint dircctionsarc r'. i60"and 60"ii.e, NN\\t- ln certainlocal circnmstanceg, rninor aqnifei-s can SSE anri WSW-ENE). The NNW-SSE set be highiyvulnerable tt'r poliutiori'(NRA 1992). givesthe impressionof being the most weli TheCoal Measnrcsstrata consist of repetiiive developed,most continrious and rvitir the larges't cyciothcmsof'shales. sarrcistont:s arrcl coal. lt is apertureat outcrop. generirllyconsiclerecl thal the sandstonestrerta The importance of bccldirrg-planeparaiiel are significantiy rncre permeabie tlian tlre Iiacturesat clepthin the tredrockis unknown. shales,Tne sequencetypicaliy has low porosity. The opennessand frequencyof such fraclrires andgroundwater ffow in undisturbedCoal Mea- typicallyc-lecreases with depthin many fractured suresis dominatcdby lractureflow (Crippset al. formations,due ro increasinglithostatic pressurc. 1993).Examination of ou"cropsindicates that, in therather rnore massive sandstones, fractures are typicallysparser! but of greateraperture tha.n in The made ground the mudstonesand shales,resuiting in higher hydraulicconductivitics. Large areasof the study site are coveredby Vlany hy Suppliedby The BritishLibrary - "Theworld's knowledge" 294 . D. BAnNKSE'l' At- i il: t5 ; -T-it'EE I t : I il1 N lii t:z e ili u)= fi) tl -(t fll) Fcl >(f tiii o< s 11ii ri\ iii {i) - 5i1 I a I r( Ni Ec al) t F #l tr Iil lii *l/f .-rl- F '-isEi i tr 8" \ Ba EL-'' 1\ t :z' ,,F s.1 'EEE O o t =-J / l\i" ! .-- -.1 * (\J-!' Eo. lt- d aa F F d & ,'- " "The Suppliedby TheBritish Library - world'sknowledge" 'T,AR I)ISPOSALOF AClD VJASTES 295 +I t 'lltt !li i1j N 'ril = d !ij t!= tll: -o FO ilij =t5 ttiJ c6 rl o< _-rL: _:l--:-- - tl: l! iJ. lii frJ (J ti q.) lI a \ri q u i.. ii) ,t1 tr1.\ tr t- v." ii l:i tl 4ii C) ili o ii,i q) i-- I , E q tsrO (f CL 8 F q, F # l-l TJ t t4t of V CJ I 0 5 t - 1v'l , l," -lF h I tJl-lit : Ro \,- cl i-: I @\- a i@f I c! i.--;r.: a t tr n CL e a o ta ra bD il 6..--t:-l t-.. Tl-- Ft-:r:^L t :t----- tt?L^ --_^--tlt- l--__ r_ l__tr 296 ,p. BANKSET' .41.. Table4. rlpprtttimtrtt,tur pit r 6?0 E E 90 i40 I i :i 3S!t _- - - : i30 0 l.5s Fig.6. Geoiogicalcross-section through the stuCysite. hascd on siteinvestigation dara, liom borehole826 to H2. Thc line of sectionis shownon Fig. 5(b)and runsliorn west(lel't) to eastlright). The verticalscaie is in rnOD 1i.e. metresubove sca level).anci the horizontal scaleis in metres. 'Fha Q,,naliar{ hrr Elri{ieh I ilrrrnr - rrTha rnrnrlr{tc knnrerlar{nrrt' I)ISPOSALOT.' ACID'IAR WASTBS 29'l N TOfAL f{,MBER OF POLES. 118 %"E 5 P6LES.5.06% N! gPoLEs st.6z/t N0. O'SCONTINUTY APPROX.JP OIP URECTION BEDSNI6 PTAAIE r6' 090' 2o JONI PLA/\,|E JU s2' 2b JOT.ITPLANE 9q 062' 3 I JOINTPLAI'€ 8d_- 325' Flg.7. Srcreographicnct showingpoles to mapped fractureplanes. However, it is possible to regard the coal 1995).There will also be hydraulicinterconnec- workingsof East Derbyshireand Nottingham- tion between the various worked seams via shireas forming, to a largeextent, a hydraulically shaftsand other vertical connections. continuous,anthropogenic, multi-layer, rapid Currently, mincwater levcls in the Notting- flow aquifcr systcm (Dumpleton &. Glover hamshire/Derbyshirecoaifield are managedon 'fable 5: Summary of tracer testsin abandonedcoal mines of the !'orest of Dean ( after Aldous &. Smart 1988) Ssturation conditions Flow conditions Distance of Dye recovery Travel velocitv travel (km) (%) rnday, -t ms-1 Unsaturated Low 0.5 108 l 840 0.021 High 0.5 63 160000 r.8s Saturated 3.6 I 460 0.0053 2Stt TJANKS fl2,, D. f;t' 4t- Tnblc 6. Lstintutt,sol ultyurott lrydruuiit't'otidwtivitI itt orar.flovina rttotrilorirt.qhor?lnl(.r Borehole O t. 7r+ /("' ,(,, ') l) finrs (il lbove (ln) (nr-s-') (ms- ) irns ivell top t FII 6.3x l0-s 0.ll 9.rJ5 -1x l0-s 3 x lO-a 3 x 10-'i H2A :i.6x l0--i 0.65 5.0 I x i(i-j 2 x l0-5 ixlU- H4 4 2 x l0-a 6 )-) 8x10s I x l0-5 i x l0--< - -_--( Br7 3.2x l0-5 0.6't 8.0 )xi0 7 x IO-t' 5 x l0-o i"n.apparent transrnissivity. (r. apparetrthvdra,.rlic condnctivity, Z. length of boreirolesection open to formation. . 'f r. head irbovcground ievel.Q. 0orv r:{te under ariesianpressure nt ground level. Banks (1992). Sorrrcrville | 1986). '!-hese a regionalscale by pumping at straicgically degreeof infilling. are closelyrelated to locatedshafts (Awbery 1988:Lemon 1991; the lithology. beddirrg,weaftering/aiteration Banks et al. 1997),the nearestof which arc stateand structuralsetting of rheserocks. The detailedin Table9. strongand brittle sandstonesare generally more Morton andBlackwell iie sonrel4 krnNNE of pcrmeablethan the morc ductile mudstonesas the studyarea and pump frorn a higher.strati- liaciurcs in the former tend to be open anci graphiclevel than ihc seamsbeiow the tar pits. interconnectedthroughout rhe massof the rock Woodsidelies some 4km to the SE anclpumps comparedto the finer-grainedmcmbers in which frorn (among c,therhorizons) workings in ihc theyare shorter. narroryer and commonly blocked Kilburn scam.Woodside Pumping Station is by degradationproducrs. believetito drain waterfrom ovcr 20 abanConed It is possible.by measurementof fracture pits. includingthc group around thc study site, propcrties (such as orientation, spacing, Pumped water is dischar"gedinto tkie Nut aperturc,roughness ancl infilling), to estimatc Brook. British Cloalare of the opirrion that the bulk hyciraulicconductivity of the rock in water liom workings bclow the study sire certain directions (Hoek & Bray 1981). woulcl drain down-dip towards Woodsiclc Alterriatively.Cripps et ai. (1993)have carried ratherthan to Blackwellor Morton (A. Ttarnes, out empirical measurcrnentson the hydrauiic BritishCoal, pcrs. cornm.). conductivityof the Coal Measuresin Shcffield In addition,a major opencastsite, Kirk Of,en- by mcans oi ln situ iests in boreholesdrillcd cast,is beingoperatcd some 2-3km ENE of the for a ncw sewer. A total of 18 tests were studysite. The sitecurrently extet'rds to theDccp carriedoul. largelyin mudstoneor interbedded Flard seamat some40 m dcpth, whereinllows mudstoneand siltstoneanci the mcanhydraulic -l from old workings were encountered.The site conductivity recordedwas | .31x l0-s m s is dewarere 6..-^li^,l L., Tha Drilioh I ihr-aar rlTJra..rarlr{lc lznarrrlar{aarl D]SPOSALOF ACiD TAR WASTES 299 Hydrogeoloql ql tlte studr'.site Severariinteresting observations can bc rnirclc irom this figure. Cverail the hyCrarlic conduc- H.t'tlraulicconduttit'it.1' csliutcttt.t A coiisider- tivitiesrecorciecl fall wiihin the i"an-teof resuits able numberof watcr strikesduring drilling for matrix condnctivity of sandstonesgiven iry occurreciin the rnirclstorre.Water was also Ycungcr (1992)iind also thc bulk conductivitics encounteredin the sanclstonemembers and at ol'siltstoneand muclstonegiven by Cripps cl rrl. coalseams. T'his paiiern suggests tirat the rluci- (1993) (see:rbove). As can be seeirfi'om Fig. stonecontains tiactureci zones where hydrar"riic B(a), the hydiaulic conductivity appeais to conductivitiesreach values compnrablc with increase with clepih belorv ground level. As thosein thcsandstoncs. frac'turing is morc intcnsc ncar thc surfacc, Figs Hydraulic condlrctivitywes estimatedby 8(c) anci 8(r1)appear 1o suggestthat hydrarilic measurementof the specificcapacity of the four conductivity increaseswith increasinglrrrclure borehoieswhich wereartesian, by allowingthe spacing. This appears io contradict the con- ffow to stabilizeand theu meilsuringflow rate cltrsionsof Cripps et a!. (1993)and may be cjue (Q), undera measuredartesian head (s). The to the fact that fractures close to the suiface rnethodsof Banks(1992) and CIRIA (Somerville may bc cioggcd by wcathcring prodricts. It mtry 1986)were then used to estimateapparent trans- aisorellect the iact that Cripps ct rr/.investigated missivityand hydraulic conductivity of theaqui- a single lithoiogical group (mud- and siltstones), fer sectionscorresponding to the well filter whereasin this studythe sequencealso contained length.The results are given in Tabie6, although sandstones. It should be remembered that thc valucsof hydrauiicconductivity dcrivcd must fracture transmissivity is proportional to the 'oider oniy be re-uarcledas of magnitude'csii' cubc of fracturc apcrturc for planc parallcl mates.as a numberof assumptionsare implicit fractulcs ancl thus a i'erv, wicleiy spaced but in the analyticalmethods, possibly ihe most open lractures iin sandstone)may ire more trans- importantbeing that of two-dimensionalradial rnissive than many densely spaced fractures of inflow. The estimatesindicate a hvdrauliccon- low aperture (in mucistone, tbr example). ductivityof around !0-smr-1, *hiclr is typical Hence, care shorild be taken when trying to .11 of a rather well-fracturedmudstonc or moder- estimatehydraulic conductivity from parameters 4 ately-liacluredsandstone. The Ko valucs also such as RQD and FI. cspccially in thc typc referonly to the rock within the immediatevici- near-surlarceinvestisation common at con- 'large of nityof thewell, rather than giving a scale' tarrrinaiedsites. valuefor K.. Falling head testswere carried out in non- Water-tahle elevation The groundwater head artcsianmonitoring wcils. Hydraulic conductiv- distribution at the stlrdy site is found to be com- ity was estimatedusing solutions given in BS plex and three-dimensional,where terms such as 5930(British StandardsInstitution 1981)and confined and unci:nfinedhave little meaning. In Hvorslev(1951), and it was found that the such a situation, water level readingsin deep resultsfrom the two techniqueswere generaily piezometersrepresent rvater pressuresat depth similar.Rock Quality Designation(RQD a in the aquifer and not necessarilythe level of measureof core recoveryexpressed as a percen' the water-table.The water-table is. for practical tage of drilling length; sec British Standarcls prirposes, defined as the interface between satu- Institution l98l) and FractureIndex (Fi - a ratcd and unsaturatcd strata. Thc clcvation of measureof fraciure intensity, the number of the water-table is best apprr.rximated liom clearly identifiable fractures per metre of core; groundwater readings in shallow piezometers see GeotechnicaiEngineerirrg C)ffice of Hong and irial pits, wherehydrogeological conditions Kong 1988)were caicrilated from coresfor the approximateto unconfined. scctionsof borcholccorresponciing to the well On this basis,the water-table at the study sitc Iilter.Figure 8 displaysthe resulis of conduclivity appcars to foilow a pattcrn typical lbr relatively testingas follows: iow-permeability rocks (Thorne & Gascoyne 1993).lt seemsto be a subduecireflection of the r conductivityversus average depth of the well surface iopo-eraphy lying at orrly I - 2 rn below screen(Fig. 8a); grcund surface. The general fail in witter-table o conductivityvcrsus pcr ccnt sandstoncovcr is from west to east, providing a lateral head thc well screen(Fig. 8b); gradicnt driving shaliow grounchvatcrthrough o conductivityversus erverage RQD overthe weil {he superliciaimaterials generally towards the screen(Fig. 8c); stream. However. grounciwater flow and con- o conductivityversus average FI over the well taminant transport in the deeper j':'actured screen(Fie. 8d). aquifer will be -soveniedby the orientations of 300 D. BANKSET AL, la I>l \o c\ o\ rt ...i ,., i- E \D_ .r| tr- *n T.y' Its rir .a\O S a -: t*- o r- r\6 c)- fo hN c{r.l rr; V l'5 IE l'= .f, ..e*O -.{ .,1 €A - IE r)_(\{r Or oEoXEo c.i;4- oF s t.: hrf) \O14Fa-n6 dl;Nr=F r;: v lc IR l8 ^€.t.chR o^ l'- 'l (t,l {.,t @' r * + o- € l5 rr(\l rtF-El-) to RRsB?H*e? la 1.5 lc (! c.l -8 3- €o_., . t_ tat et 6l lq. vn 16< _* v o,l | 6,) ic) i,L OO F-. t\ t lh -C\ C\(\l Qr rrrnliar{ lrrr The Flriliclr I ihr:rnr - ttThc rarnrlr{tc knmrrlcrlnett DISPOSALOF ACID TAR WAS-I'I.,S 30i P.ri..blllty (n./r.cl (BGLI m o€-o7 1.oE-o5 r.o€-o5 | 0E-0a _-ffi1l Om',rl----- r ffif I .oi 70i uolI 601 {of! 30l- roII rol "l_ t.oE-oc fo€-oa roE-o4 e) Av?reg€ depth ol uelt acracn Pernnability (nfaec) c) Avcregc RQD ovcr wrll lcreGn lenglh * S!t/.lsl l .li I I $o I I I I I I I i I I t.oE-ot 10E-o6 toE.ot r.oE-oa r0E-0G to€-ol 10€'0. Permoability (m/scc) P.rnabilily (n/rec) b) t ol eandstonr o{ riltatonG d) AveragrFl ovar srll lcrlen hnlth Fig. 8. (a) Hydraulic conciuctivity versus avcrage depth of the weii screen(in metrcs bclow ground level). (b) Hydraulic conductivity lersus per cent sandstonelsiltstoneover the wcll screen(for non-coredholes, this is estirnatedfrorn drilling cuttings).(c) Hydraulic conductivity versusaverage RQD (British StandarcisInstitution 1981)over thc wcll screen(as RQD increascs.the liacture intcnsity decreases).No points are plotted for holcs drilled by open-hole(uncored) techniqucs. (d) Hy thc most extensivefracture setsof the greatest This pattern is further complic'atedby the aperture(Bradbury & Muldoon 1994).At the existenceof mine workings.If the mine system studysite, these are probably thc bcclding-plane is pumpedor freelydrainecl, this may result in parallel(i.e. sub-horizontal) sct and a prominent regionallowering of water-tables(Anon 1993; sub-verticalNI.IW to SSE fracture set. The Younger& Sherwood1993) and/or high down- formerwill not introduceazimuthal anisotropy ward verticalgroundwater head gradients (and in thc flow, but the latter liacture set may tend thus potentialfor downwarcigroundwater flow) to in 92 26thAprii 1994 9l 323+ 90 89 817 ! 588 987 I E86 -E 85 ts4 g fi83 €a2 B6 !l I 5ar i' -.2A Sl 80- ,i H6ur -9] 8I 89' r i, .1, H2 H3 78- , a Bll 77 5C 60 70 80 Elevationof centreof filterDack -rnOD UpperSandstme 1 Mwiatoneund€r Lou,er Sandstone n MiddleSandstone .s l\lbrleyMuck r LoryerSandstone . ilrede Ground,Tar Pit 1 Fig. 9. Groundwater head in boreholcsat siudy site,ploited ergainstelevation of lilter pack (both in metresabove seil level). clayeyaquitarii subject to downwardflow into an andvery anomalous in termsof its veryhigh arte- underlying aquifer was simulated.Thc main sianhead (some 6m). No sati.sfactoryexplarration conclusionreached from rhis sirnulationwas has been found for this borehole'sbehaviour, 'because that of the inherent difficultiesasso- cxceptpossibly that iL wouldappear to indicatea ciated with identifying lthe most influential] discontir:uityin the faciesor fracture sysiemof lracturesin cores... and becausesuch fractures theaquifer; conceivably even a i'ault. can producea highly effatic headdistribution In surnmary,it is believedthat verticalhead in the aquitard,there will be much unccitainty gradientsand possiblyalso vertical (downward) in predicting contaminant transport jn such flow are dominant at depth over iateral heacl sparselyi'ractured aquitards.' gradients.A probable cxplanationtbr this 'rreneathis Cessationof pumpingor drainagemay result thc cxistenceof coal workingsat depth in rising groundwaterlevels, resaturation of the sitc, which may irc connectedto pumping overlyingstrata and re-establishnrcntof a drai- mine systcms.The overall effectof theseis to 'drain' nagepattern dominated by more naturailateral the site from below. gradients. head -boreholcs However,the existenceof artesianboreholes Groundwaterlevcls, as measuredin (Hl, H2A and H4) indicatesthat upwardsheacj on 26 April 1994,are plotted in Fig. 4. There gradientsare also of importanceiocally, particu- appear to be strc-ng vertical groundwater larly.but not exclusively(e.g. borchole Bl7), in gradientsat the site, with a generaldecrease in the vicinity of the stream,a typical discharge groundwaterhcad with ciepth.Apparcnt down- zone, implying that the stream is influcnt in ward verticalhea Srronliedbv The British Librarv- "The world's knowledoe" 'IAR DISPOSALOi-' ACII) \VASTES -1tJ -1 Hydrochemistryancl groundwater Mulclooni9q4), br"it is probabiycontrollccl by contamination iracture patl'l\vays.Tiicsc inclucc;t nc'rrtilto soulh componentol groundwa.terflow in tlre A selection of hydrochemicaiparameters Coal Measrtresstratii, probably' controlied iry mcasurcclin groundwaterin the rrronitoring the main NNW-SSI liacrure set. This docs wellsand in theiakes, streail and triai pits.are not. lrorvever,impiy thal contaminitnttransport shownin Tables7 and 8, In Table7. valuesare wiii only takeplace triong ihat NNIV-SSElrac- comparedwith concentrationsrccordecl in osten- iure set. The intersectinglracture sets (both sibly uncontamitiatedshallow Coal l\4easuresstrb-vcrtica!and sub-horizontal)'rvilleffectively groundwatersin Derbyshireand Yorkshire tty irnparta high degreeof matcro-scaledispersion Banks(1997 ). In mostboreholes, ccncenr.rations of contaminanttransport, witir signiflcantcoru- of sulphate.calcium. magnesiumand heavy ponentsin both southerly(c.g. contamination metals are generallyelevated with rcspcct to in H4 and H5, controileclby the NNW-SSE background,although only in 87 ancl H2a is fracturcs) anci easteriy(contamination in i{2 the pH significantlydepiessed. suggesiing thai arrcl H2A. controlled by the prevailing head acidhy tr, J t- ?L - 6-!a:_L I -ilt^ l--^---l^l-^tl 304 D. BANKSET AL, t= 8*' !"t:: ':q-:R ,()f9 t--cJ r.-4 c'C COCOCO -n(fr O- o piE I r\g VO\ -F.l-O.lc.,- (*. VVVVVV V V V a u o' c.t o* 0.) L l-- c.l 6 a * o. \t q) \O a.l la) e roo 1!qqr\4).ne-t Qcccc>c)c €. dnl o \l' .{-\O- .il-i -?ira- t\ C..l Vtat [) h VV V V o -o e. g c* a .s \O tt 6l roO o o ri o.+ '-: Fr €t/)(N .c c.l a\t - i'. e'lI s c\l t !f F 0 r (, r-. ! C) o\ t-rrt dor ^.1 v s 00 F- e{ - \/ - B F a e * o. 0 -c,2 €o .o E6 r-o\ (f,solJ|0\o coooooc tr. ^oo .n r,a{ q\ t{t-nJ-t\.nN o+ s rZ! ..) VVVVVV \ e _i3 tl) i - otr.l q GI c.l€' r.t(.\O.'iri.+ ifoooeOO c\ J c.l a{ra} -N \qJ =ao €r.|a-.1 \/-C-Ft' F-r)O o >-g F, l*- - O.l O\ s l q.f 3 () 0.) q3 G' t, ! s f{} o\ Fr .,:! $ $ F i Eg :t 4 g 6 9 a) 9* F- .s tt2 tn *= i.) :t !. I ;,-T::bo rs j-i;oP s =- IJ. cl 6' F a E (n ; > ==zAV i, a) .= = | 1 .,n ,^' / F u D a --= .6 F AHegzvdg rUo6zf s P88#5 € z Qrrnnliar{ hrr Tha Elritich I ihranr - 'rThc \^rnrlr{rc knnruler{ne" DTSPOSALOF ACID TAR WASTES t()5 Table9. Pmnpinllsiutlts.li'om cottl ttitrkingsitr tira t'it'itrit.t'ol rhe .ttudt'.riiv Pumpingshaft Quantity pumped(1987) Locartion Dcpth rn m year BlackwcllA-Winiling I s50000 InrrneCiatelyS of Tibshell ar approx. To BlackShaie Grid Ref SK 43 58 horizon Morion I 450000 lmrnediatelyw oi'Tibshell at approx.Gricl Rel'SK 4l 60 Woodside s 640000 West of likcston. near Stanleyand To KilburnSeanr Mapperiey, at approx. Grid Ref SK 40 44 ' Lemon(1991). system.The main pointsof the conccptualmoclel (l) Vic surfacerun-of. Duringnornrai weather afe as foliows: conditionssuch as rvereencountered during the srudyperiod, no run-ofrol contaminatedsurface part of the fill and weathered In the saturatecl wsterfrom the siteappears to occut.This obser- materials,which, aIthough hetero- ovcrburden vationis supportedby the factthat tar-pitrelared geneous, be consideredto be, more may contaminationwas not foundin thestream at thc the underlyingCoal Measiircs, isotropicthan eastof thesite, either during this investigation or groundwaterflow is likelyto foliow thegeneral during previous monitoring by the NRA gradient . eastward,over {P. of the water-lablc,i.e Ree'res,NRA, pers.comm,), This doesnot pre- the smalistream. mostof the site,towarcls cludethe possibilitythat, duringextreme rainfall proper, a lateralcom- In rhc Coal Measures or snow-meltevents. run-off of contantinated poncut gradient is likeiy to occur, ol head surfacewaler from the siteto the streamnright from westto east.Extant fracture alsodirected occur. will, however,constrain the dircc- directions (2) Via shal[otu groundwater in superJicial groundwatcrcan ffow. The tion in which material,s.The lack of hydrauiic conductivity NI\rW-SSEfracture set appearsto do:'ninant measuremenrsin the fili precludesany quanti- to the flow of induce a SSE component tative assessmcntof this possibility although groundwatcr associatedcontaminants. and observaiionsof water seepagesinto trial pits that this is occurringmay be An indication indicale low valuesof hydraulic conCuctivity the of hydro- deduced trom distribution and henceslow groundwaterflow rate.Thc fact parameters. chemical that contaminationhas not ireenfound in the gradientsalso appcarto be of great Vertical streamadjacent to the sitcsuggests that contami- Measures, importance deepcr in the Coal nantconcentrations of a magnitudewhich would groundwater ffow presumably being with be unacceptableto the NRA (i.e. infringing olcl coal workings,being drawn down to Water Standards)do not reach the pumped pumpingstations. Quality from distant streamvia this pathway. hydraulic gradicnts are Locally, upwards (3) Via lateral groundv,ater in the Caal boreholes.These f,ovr indicatedby severalartesian Meusures.Hydrochemical data and theobserved vertical head may refleci remnantsof natural fracturepattern suggest that oil-sitemigration of gradients, grountlwater to stream i.e. discharge contaminantsis occurringto a Iimitedextent in a of and down- valleys.Thc combination upward generallysoutheasterly and, to someextent, €ast- gradientsis not necessarily ward verticalhead erly direction. It is possiblethat some of the for thediscon- contradictory,but offersevidence groundwaterflowing through the site via this of the fracturedCoal Mcasures tinuousnature mechanismeventually ciischarges to the sheam aquifer. furthersouth of the site, (4) Downr;ardfow to underlyingcoul workings. No determinationof verticalhydraulic conduc- Contaminant fate in the hydrosphers tivity has been carried out. On reachingany coal workings, any contaminantswould be Dissolvedcontaminents subjectto a largefactor of dilution bcforebeing dischargedat Woodsidepumping station. bear- There are four routesby which dissolvedcon- ing in mind that Woodsidereceives water from tarninantscould po:cnriallyreach watercourses over 20 abancioncdcollieries, each with its ou'n via thc hycirospherear the studysite: complcxof workings draining extensiveareas. ?l A rr. I t .l tltl tl tl ll 5 tJ1 pa I FJO o_o rDd qd G' r+ FJ - . .r7r? -t w \v, (Dpr cDp d g-oxsq = Crq o (n o' dg-l -n p d€ lJ1 r+-a =. J p \, -. s+t-a -R f-f = o_r o CT - -t o5 J -'f oo -)o P6 tr!: oo-t o! L-t -. -. gfr' = c''q r+ o=' q Fi =' a- s rrj p o- Fo-i op) o d* o! C;r -r(] F) d6- r-i- pJ iT p ra -l (D o- = IJ\ m o @ - a t+ Suooliedbv The BritishLibrarv - "Theworld's knowledoe" I)ISPOSALOF ACID TAR \\'A:TES i07 Comnarinstlrc area ol' the cLlntiirninitiedsite incrcascin iaieral groitndwitterf ux frotn tlie site (r'. ZOOOOilI)*itt.r the potentialcatchnient area tolvatc'rsthe strr'iim. unclercirainedby lVoodside(say. 5 x 5 kn: as a flonsideration of a potcntiiil rise in ground- ct-nservativeestimate) a dilution factor of the water heaclsand in Iateral groundwaterffrix in t-irderof at leasi l0- to 10' may be expected- the futurc must be tiiken intc $ccount in the (The ycariy pirmping rate of WoodsiCeof asscssmeniof remedialoDtions for the sitc. - i 5 x 105m-i year , coupled with a typical groundwaterrecharge rate. is consistcntwith a catchmentarea of at leasl that order ol' mag- Remediationoptions nitude.) A more disturbingscenario would be ihat of opencastingoi' coal (with concomitant The fractured.anisotropic and exceptionaliy pumping)adjacent to the studysite. This scenario complcx nalure oi- groundwaterflow at the is currcntiyihe subjectof a planningdcbatc. stuclysite rendersany aitemptat groundwater clean-ripextremely cxpensive ancl with a iow Light non-aqueousphase liqticls (LNAPLs) Tl chanceof succcss.This observation.coupled is known that LNAPLs are generatedby the with the currcntlack of any measurableirnpact tar pits as theycan be observedas films on thc on r;fl-sitesurface water receptorsand the lack surfaceof the soi.nhernand middlelagoons and of water abstractionsin rhc vicinity which also in groundwatersamples takcn tiom bore- might be consideredto bc at risk arguestrongly hoies87 and 51. The fact ihat no seepageof againstan attemptto rcmediatethe quality of LNAPLs hasbeen observed i:l the strearnntay the groundwatcrin ihe Coal Measuresrquilcr treindicative of thcirlimited migration, although system.Nevertheless, the fact that the wastcis veryfew data exist to draw definitiveconclusions measurablycontaminating groundwatcr below on thc presenceof LNAPLs within tire aquiicr, Itre siteand that the grorindwatcr.with possible Most of the hydrogeologicalborehoies are futurecessation of minedcwatering. Irray undergo screenedat sornedeprh below the water-table changesin flow rcgime,render the removalof and would not be expcctcdto cietectLNAPL the contaminantsource (i.e. the tar pits) highly phases. desirablc.Other factors ir, favour of someform of remedialaction include the foilowins: plnse liquid.r (DNAPLs) Dense non-aclueous o odourl a as The tar itselfcan be regardedas DNAPL, c risk to usersof the sitcand wildlife from direct the lagoons,but it it tendsto sink on reaching contactwith the wastes; be viscous migratedownwards appearsto too to o highly visiblecontamination of soilsand sur- great extcnt in the aquifer, only beir:g to any facewater lagoons; Measuresin very encountercdwithin the Coal r politicalpressure to cleanup what is perceived fractures.A further, largciy fcw near-surface to be a highlyundesirablc site. unexploredpossibility, is that of the gcneration of lessviscous DNAPLs by thc weatheringof The excavationof ihe contaminatedmateriais is thetar. seenas beingriesirable. Simply capping the tar waslc to reduce infiltration of rainfall and clirectcontact with the g,estewoulii be cheap Future dtvelopmentot' groundx,ater and would leadto a reductionin risk. It would, conditionsat the site however,not fully addrcssthe issueof ground' water contaminationand wouid be unlikely to Thereis someevi Tabfc 10. Surtvrtor.t'o.lttt'st'ssmen! ctl'.r.i.rrtis! rencdial option:; ut the.tt:t(l.r',sil( Treainrerrt Assessment Er .ritr biologicaltrearmcnt (biofarrning) Tars too refractoryand acidic /n sila hiologicaltreatn:ent (biorenediation) Tars too fefractory and acidic In situitquecLls, solvent or steamcxlruction Low tar soiulrility,high vlscosityand low matrix permeability fcnciertecirniques rinrealistic C'ementstabilizatiorr; siliidi fr cation Treatmentshown to havcpoor successrate in soilswith high organic content as organicsimpede cement set Vitrification Energy deinand and cost excessive.Presetice of combustibie material precludcsuse of techniclue Incineration Applicable to acid tars subjecl ro ccntroi of acidity pre-treatment Vapour extraction Low volatility of tars preclr-rdesuse Soil fiushing Low soiubiiityof tarsprccludes use The sitcwas subjecl to a semi-quantitativcrisk centred on the coallieldsof the UK. The assessmenltcr identify critical risk pathways ancl growth of manufacturingindustncs drove the those which would bc affecteciby the various dcmandfor large quantitiesof coal to provicie remediationopiions. The options wete subject power 1o the urban centres.Three ccnturics to cost-benefitappraisal, with an outcomeas later a large portion of the once-extensive summarizcdin Table 12.The final sclcctionof activecoal industry has been closed with an asso- remediationoption is currently under discussion. ciateddecline in the heavyindustry. A legacyof this industrial activity neverthclessremains tociayin the form of large areasof land and Discussion: drawbacks of the study groundwater(Dowse & Selly 1975)contami- natedby a wiric varietyof potentiallyhazarc',ous As in most similar,single-phase studies, the site inaterials. investigationexhibited some limitations,many The rnechanismsof fiow, contaminantrans- of which coul 6..--l:-l r-.. TL- Ct-:r:-L I lL-^-, ltTlrr ..,^-lIr- L-^.^,la;laarl t DISPOST\LOF ALIID'lAR WASTES 309 Table 1l. Derailetl assessfttcn!of sebctedincinerulion cncl cncapsulation r(n4Ci(ttion opt[on.s Rcmc l. ExcavaieanC place in nn cu-stte o Wasie lotaiiy contained.lvlinimal o Leachatc produced wr1lbe contained contaiumcntcell environmcnlirlconnmit:ation. anciconccntrated vrith wasteremaining o Free tar is encapsulaiedand preventerJ intacr indefinitely from migratron o Exactquantity of wastettnce;lain prior o Cheaper than remcdiai treatnenl of io excavatiott waste r Exlraction may destabilisewaste r Reducesodour pioblem r Problernswith groundwater o Chemicalphysicalstabilization of milnagementduring cxtraction wastescould be attcmpted prior to r Requireslong-lerm mai[tenancc and emplaccment matragemeot o Grcatcr f,exibility lor maximurn r Long-term efficacy/performanceof gas utilization of the siie in fururc venis and gcomcmbrancsunknown development 'tlo- 2. In situ capping r Aestheticallyprelbrable to r Continued lcaching of contsminants to nothing' Eoundwatcr r Leachategencration reduced o Area of tar pits stcriliztd for future r lf excavationis miuimized,little risk of dcvclopment cotrtaminantmobilization or spillage o Waste is still wlnerahle to future during construction changesiu environmentalcondirions r fusk of direct exposur€to uscrs ol site (e.g. cessationoi mine pumPing) reduced r Full containmcnt of tar is nol achievcd, r O 3. Excavateand disposcat an r Considercd unrealisticdrr to difrcuity off-site landfill in linding a lanrlfitl fttcprrd to sccept the rvaste. 4. 'Do-nothing' option r Low cost r Aestheticailyand'politically' o No significant current water pollution problcmatic risk identihed with rz sl'rswaste e Continued odour problcms r No possibility of further mobilization r Risk associatedwith continued pubiic cf contamination duc to remedial acccssto srtc worls o Site unsuiteblc for rcdcvelopment o Continued opportunity for fiow of tar o Possibility of incrcasedlateral run-off of dissolvcdcontaminatrts caused by future cessationof minc PumPing . Future legislation could imposc one of the morc costly options al a futurt dute. r Requireslont-term msintenanccolsite fcnccs,e1c., and monitoring of waste r 5. On-site trcatrnent of heavily r Waste totally contained r As Option 1 conaminated wastcsby fluidiscd bcd o Free rar dcstroyed o Requircs HMIP aPProvei incineration; on-site encapsuiationof o Greatcr flcxibility for maximum moderalely contaminatcd matcrials utilizationolsitc in futnredevclopment o Leachatein cell lcssstrong than lor Option l. r 6. Off-site lreelment of heavily . Crcates a clcan site, free from e High cost contaminatedwastes bY high developmcntconstraints e Need to neutralizc tars beforc temperalure incineratioa; ofl-site o Providesa completcsolution to incincration landfiil of moderately ccntaminated environmentalcontaminaiion o Exact quanliticsofwaste uncertain materials o Protocls all sensitivctargcts, on- ani prior to excavalion off-site r Problcrns with groundwutcr o Does not requirelong-tcrm site manaScmcntduring excavation management o Significant traflic on local roads "l t . ln .ritutrcatmeni of wastematcrials r Unviable:no trcatmcntmethods idenrificriwhicb are suitablefor wastc and soil-typcs involved. ir0 /.n- D BA,I-KS ET .41.. Tqbfe 12. Sunvrnr.rol (ost:her'qlJd,' ,'-tis tt rt'nu,tliulopti0n.\, Option no. Description PcirnanenL'e i.liskrcduction Cost estinrate(fM) I On-siteencapsulatioir. <,.r sitrr Ivlectiumterrn lviediirnr.high >1.8 On-sitecapping. lr .rrlrr Medium ternr lviediurn I,U 4 Do notiting(and nronitor) Short term Short tcrnr 0.1 5 On-siteileatmcnt and Long tem: Hi-eh i.i-4.5 encapsulaiion 6 Off-sitc trcatrnentzind landfiil Long term Aimost total 24.8-42.3 r Vline workings.shalis ancicoiiapsed strata References abovc mine workings representrapid trans- port pathwarysfoi'water and contaminants Ai-rxltis,P. J. & Suenr, P. L. 1988.Tracing ground- o Vertical groundwelterheaci gradielts are waler movement in abanr.loned coal mined highlyimportant, being induced Lroth by topo- aquittrs using fluoresceni dyes. Ground Watu, graphic effecisand undcr-drainageby coal 26, 172-178. workings. & Bucr. J. A. i986. Groundwaterman- agementproblcrns of abandonedcoal mined aqui- r The aquifersystem is stron_elyhetcrogeneous, fcrs: a casesrudy of lhe Forest of l)ean. anisotropicand discontinuous in naiure. Quurterll, J ournaI of f)ngi neer i ng Geo| ^_---l:^J L-- -t-- Ft-:a:-L | :L---. il't'L^...--lll- l---..J^-l-^ll - jl; DISPOSALOF ACID TAR WAS'IIS - ttl Dowsu.L. H. & Sslir'. K. fl. i97:;.Grounduaier pol- 1992.Ptlit't' tttril f't'tttlit't'lor tfu Pntlct'liotr lution in an indLrsirializcdrlar'1 trl'thc Tl-cl-il liltsirl. 0 rowuhrui(r.NatiorraL Rivcrs Autnilii t1'. ll"atar Polltttitttr{'ontutl. 74. 526-541. Pcru,l.n.S, 1994.,,:utluntinruit Turnsurrl in tirc British l)Livrr.r.roN.S. & Clovrn. B. W. 1995.Thc intpottttl Cou! ilIctnurt'l Slxtta. MSc ihesis.Departtnent <'ollicr.tt'Iosurr' on t\'.tlct r(,soilr(('s,n'iIh porIicttIur of Gcoiogl,'.Royal School cr:' Nlincs. lmpcrial rcgortlto NRA Scrcnt Trcnt Rcgittn tsritishGeo- College ot' Sciencc. Te'chrioiogy ancl Meclicrn:. logicalSrtrvey. Tcchnical Report SeriesWD'95. London. F-rvittonveNr C,rl,ro.t 1987 1990. S-r'rirre.i'tar ponds Pitrcr. lvl. 1996.lntrotlut'ing Grtnmdnrtlcr. Chitptttatr ct clean-update.Ncwslcttcr .lune i9E7 lvlarch 1988: Hall. Londorr. April 1988-March i9[t9: Apni it)89-lr'larch l99f]. Scrrrtlsti ENrrRrRtsr1.994. Hotr to fnvtstillutt Cort- SydneyTar PoridsClcan-up Proiect-Canada. iinninq|etlLnrld. Sijoitish Enterprlse,Glasgou'. __ 1989.PAHs in the tar ponds:thc sourccs.dangers Snrs.R. C. 1990.Soil rcrncdiationtechniques at uncorr- and destruction of polynuclear arL'Imatichydro- trolicd hazrtrdouswasie siles: a critical r!'vicrr". carbons. Syclneyto' poncls <'!can-up.liu'tshcet. Journul oJ the Air ond ll,'o.slt' M anagettrcni SyclneyTar Ponds Clean-up Project. Ministry o1' Assot'ittriou-4$- 704 732. Suppiy and Serv-ices.Canada' Srscrrrox. R. G. 1987.An Ewlnutionol the Treutnten! Thcsis, Fnosr. D. V. & Sturnr. H. G. O. 1979.Geologt'ol the and Disposal Options Jbr Ac'id l'crs. MSc Countrvarouncl Derb.r. Geological Survey Memoir Imperial Coilege.London. lbr I : 50.000gcoiogical sheet 125.IGS. Loncion. Svtrx. t.6.. RH.-s"C. lI. & Epcx, R. A' ltt6"l.Gcologt' (ht:sterJield, CEcrrr.c'nr*tcnlENolrrEilINc OFF'tcEoF H(,)NGK()N(i of the countrl' around Matlotk und 1988.Ceoguiclc 3: Guide to Soil and Rock Desuip' MansJietd ( Memoir o/' the Gcological Surt'ev ol' Ir'ons,Hong Kong Covernlnent. Greut Britcrin, Explanation of One-Inch Geologicul Glnsox,W,, Pococx.T. i.. Wr.trrr,C. B. & Stcnlocr, ShcetlI2, Nerr'^Sprle.r/. lnsiitution of Gcoiogical R. L. 1908. The Geologl'qf'the SouthernPart of Sciences.HMSO. London. the Derbt'shire und Norringhamshire Couifield' Sr,urti,E. T. & Bnt:ut.r'.v,J. 1982.The British Expcri- - Memoir of ihe Geologicai Survey of Grcat ence Ciean Up. !n: Hazardaus lVaste Disltosttl. Britain. Ann Arbor, 192-193. GnlrnN, A. R. 1971. Mining in the Ettst Midlands' Srrvt:nvrLrE.S. H. .|9E6.Control of Grounrltrater.ftn' /,5501947. Frank Cass& Co' TenrpororyWorks. CIRIA (ConstrucdonIndnstry Hlnntson, L B., Pritxun, A. & Wllr-trrrtls.G. M- 1981. Researchand Inlbrmation Association). Rep a-----r:^l L-- -L- 6-:r:-L | :l----' rlTL^ ...--lJl^ l.-^.^J^l^rrt 306 I D. I]ANKS ET ,4L. ?; ! li'' -€ l. €'i ll- => <: 4- ! ?2 6 tZ ri -o OU l; et) U< L ts!/ -\ 'i ili6 F ftF ..139 nl oo ', Qli h Jrn\o i)( tro I 6 /:.i '@ t!1 4F3 h o6F !e CA ii (h oe o q GJ.o q I aOl ,ri*S -l I-; ij.ol ': V;I l- - (:JI ,= F t., I ,' r.: 3J :z - o o A t- (Jl GG/ 'g E I all t- F + -i rC, o- tr -.F1 o CE \o 6 t'4 I o(t rt9 \o (D - \o m ltl (h G I/ U"t a I z, cEl a t'E oa i l:e l,Lr Z, tr -o rt F-o ; l5 sl5 :*F i t= <)< It Z-) (J a.rt- rCr / - -.- --' t\l ro It tr J} tr =-r=oY!UdA .L s cra EE- o:r = <{ EB F =Jz{u{E=EEEg F 6 -6 E O > .r e\ c Fs i! E Vte J v)'; I 3 EE g so''g ecoo ie0 Sunnlied hv The Brifish Librarv- "The world's knowledoe"