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<br />Peter E. &lrknU/I/II
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<br />SPDSS Core
<br />
<br />The Colorado \'\~\('r Con",en:ation Bo:ud i~ Clmemly
<br />implt'm('nting it:-; South Pbtlt., [)tXi~ion Support Systl'm
<br />(SPDSS) to better mana~t.' surhee :mJ ~round\....:.uer within
<br />thl;" South Pblle Riwr Ba,.;in (C\\"CB, 10lJ-.l l. A:< part of the
<br />Rroundwarer com(Xmenl of the SPDSS, Camp Dre,o,;er and
<br />:\kKee (CO:\D, Inc. drilled a hed[(l('k te"'l well in Oltober
<br />2003 at a sile north of Herlnt'tt, .-\Jam.... County I FiR I) to
<br />obtain aquifer pmpt."rty and configur.uion d.lt:! and 10 e....al-
<br />uate the intt'raction I>t'{\\'l~'n the Dem.t.'r Basin .Il]uift~r" and
<br />tht' South Plalle allu\"ium (CD:-.1. 20(4). TIll" loc;Hjon is
<br />approximardy 42 miles from the western l--tl,>.:e of the north-
<br />l'fll part of the Basin when.' tlll..' aquife~ are nO! a." deep
<br />and the upper Ikn\'er ;md Daw:<on aquifer.'i arl" ah-'o\.'nt.
<br />Core::s were oht."lined from three :<eparatt.' ime[\'ab at
<br />depths of 125 to 2.6 ft in the 100\'t~r Den\'er :lnd uppt'r Ara-
<br />pahoe aquiFers. Two samples of Fine-graint"d :<emi-consoli-
<br />dated claystone were :<elt-cted from the cores for labor.Hory
<br />analysis of \'ertical hydraulIC conduni\'jty (CD,\1. 200'i).
<br />The objectl\'e was to determine \"<mical le,lbge ehar.lltl.'r-
<br />btie;. with emphasis on pu:-.sihle hydraulic nmm:nion
<br />between the Dl'nver Basin J-x'drock a4uifer and the o\t.'rly-
<br />ing South Platte allu\'ial aquifer. CD?\112(K}I) took .~reCi;11
<br />care in handlin~ the sample" 10 pre\'l'nt ddlyd,.Hion and
<br />Illechank'al agilation of thl..' finl.'-gr.lined "edinwnts,
<br />The sampll's were an;llyzed hy Core L,b Petroleum ~I..'r-
<br />\'k'es for liquid penneahility in :lcnmlinu' with API RP-'IO
<br />mt:'lhtxJs (API. 1960l lJ~ing formation watel prll(l\leed from
<br />the Ar.lp:II}(x' aquifl'r at the I..'nd of a pumpin~ tl;.":-.1 (CO,\1.
<br />2004), Form~llion water \\',1-" u~t"d ;l.~ the satllr.lting medium
<br />to minimize tilt' pOlential for \'Olllmdric chan~e:< in day
<br />mineralogy and slrul'lllre hy the introduction of wakr of
<br />diffl'rin~ chemi:-.lry, ;I~ identified with the Parker COfl'''. The
<br />resulL'> of analy."i:-. for vertiol hydr.llllic condunivity from
<br />the two ~amples nJlIected of fint~-~r.linl'd confinin~ in!er~
<br />vals atlhis location are on the order of -'l.-xW-6 {O 3.5xlO-l'l
<br />cm/sec (Tahle 3), which arl' lower than the resulb
<br />reported for the Kiowa core, }'t:t hight'r than [t'J')()rted for
<br />the Parker cort'. Core handlin~ ;lOd analytical methrxb
<br />dosdy followed thoSt' impll'menll'd at Parker. with the
<br />exception of the u~e of natin' formation watt'r a.,> thl..' ~"IIU-
<br />r.ltinR media. However. thl' s;imple... from the :-;P[)SS ..itl.."
<br />were also ohtained from mueh ~hallower depths in the
<br />Bhin, wht:'rl' the synorogenic "l.'dimt:nt," may ha\'t: nen.'r
<br />t>t'en subjected to the "ame depth of hurial as nl'ar the
<br />deept;"sl pan of the B:l.sin.
<br />
<br />DISCUSSIO:\'
<br />
<br />The current .~et of empIrical vertical hydraulic COndll("ll\"
<br />it)' me'.l.suremeOls reprl'.~enl a \'ery ..mall :<amphn:;:: of a \-'ast
<br />}.:l.'ologic feature. not only hOrlzom:dly ;Icrn:<..; ;I n<;,arty
<br />
<br />The Rock}' .\IOllfll"," A...."OCW1I<>n 0/ ('<'0101<:'"''
<br />
<br />6iOO-mi~ b:l~in. but abo Hc'rtically through ,I 3000-ft thick
<br />"t'diml'mary 'it:'llion. On a map na.,I:<, thert. arc only nve
<br />set'> of da[.I: and of those fh'e ~l.", tht' maximum numtx'r
<br />of vel1ical J.1ta point:- with :<pt'dllL" rcfcrt:'Ol"C [0 finer-
<br />gr.lined t-onnning layers h 22. TIli!<> is ;! \'ery ..mall d:lla ~l.'l,
<br />~iven the importance of thh rl.'."ourt"t.. and the rail' al whith
<br />it is hdng exploited.
<br />E\'en with the limitt:'ll "ize of thi... data ~L the range of
<br />\";triahi1ity amon~ the result.'> is lar~e. sp:mning from lxlO-;I.
<br />10 Ix1O,II {'nv:<t'C as shown ~IJphil-Jl!y in Figurt.;. Typi-
<br />cal h\"draulic nmduL"lI\'it\" values for ..bak LlU helow b;;lo-7
<br />un'-~~c while \'alue::s f(~r silt r.mge hetween IxlO-5 and
<br />lxlO-~ l'nt'~C (Freeze and Cht.IT)'. 19~9). Some of this
<br />\';uiahiliry m:l)' be :H1rihuWhle to difference,.; in the physical
<br />propel1il.'... of [ht:' f()(:b .";Udl as litholof0 rd:ltive to the
<br />~OUrte area. Furthermore. not all of thl: \";llut:'s Ii,,,tt.--tl in
<br />Tablt' j and :<hown in Figure 7 are from sampll:s that arc
<br />nect'ssarilv shall'. TIll:ft' could ;tl~) he;- diffl'renn~s in physi~
<br />cal propertit's of the f(K:ks owing to diffeft.'m'l:s in com-
<br />pall ion hi:<tories th;ll m.IY nOl he uniform a~'fO~S tht.' Basin:
<br />not all shales .1ft." the: ....amL.. On the ntht:'r hdnd, some of
<br />thl' \'ari.lhility in an;llytical results prohably arhl's from dif-
<br />ft'rencl.'~ in mt'thods. hoth from the st;ll1dpuint of sample
<br />handling .lOd J.nal)licaltechniqul". :\Iost of thtc" results Ibll.'d
<br />aho\'l' lxlO'- cm/see art' prohahly not of tht' shale confin-
<br />in,s.;. Jayers or are nm rt'pn.'sentali\"l' due to discrepancies in
<br />s:lmple h:mdling and ll.'sting metlllxb.
<br />During evaluation of the P:lrker core, JCHA conducted
<br />sensiti\'ity analyses of tilt' analytical methods on .-.e\.t:'r:ll of
<br />thl.' sample:< The firsl analysi.~ l'onsistt'd of pt:rformin~
<br />replicatl.' analyo,;e,,, usin,l.: the sallle ffil.thlxb and saturating
<br />mt"llium on the samt' samplt'S in order to measure variahil-
<br />it~. witblll the ~anw lllt'thoJ, while tbt. second sl'nsiti\-it)'
<br />analysis con....lsted of comparing ;lOalrtk;J1 r('sull'i from
<br />ll:<in~ watt'r and comp;mn,g them with the an;ll)tic;J1 rl.'.'iult....
<br />from the same -"ample llsin,s.;. a differenl meth(x1 with air :1."
<br />the satur;uin~ ml'diutll. The:: rl...sults of hoth "erl.~itivitr analy-
<br />"l'~ (Table -I) art' revealing and gin" a M.'rL"il' of how critical
<br />the ~dection of ml'thcxlls and tht' prt'chion of the result...
<br />For the rtc"plicate analyses Within the same meth(x1 using
<br />the same "3turating nwdium, thl" differl.'nce:< in re'iults of
<br />anal~'ZmR the ~;lme ~amplt.s are within an order of magni-
<br />tude, However, the differem.'(:'s in thl' rl.'~ult:< from different
<br />method... using differing s:ltur;\tin~ media are very signifi-
<br />C:lnt, rangmg I"lt:twel'n one :lnu five order< of rna!o(nitll{k,
<br />rbrkrnann anu Edington L:!OOll attrihuted the difk'fence
<br />hetwt:en the results from the difft:rt'nt meth(xh to change~
<br />in the day StruLturl' m [he ...;ampltc"s that prohahly occurred
<br />during prepar-.!Iion of tbe ...amples for 3nalysi.. with air. Tht:
<br />clay.. in thl.' <;amples presum;lhly remainL-u in a maximum
<br />state of swdling a~ long as the sampll.'s remained hydrated:
<br />however. those same clay... may have under~unl' shrink:lgl'
<br />and/or cracking upon drying for rhe te<;ts u..in,l.: air. llw
<br />o,;en.~itl\'i{y ;Inaly"t's dearly indicate thaI tn;llntaining clay
<br />struC1ure in ;1:- near a naturalsl.lIe a." pos:<ible i:-. ah....olutely
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<br />IKO
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