Nuclear waste

Ge­o­sig­ma has mo­re than 20 ye­ars’ ex­pe­ri­en­ce in the fi­eld of nu­c­le­ar was­te. We are par­ti­ci­pa­ting in the de­ve­lop­ment and imp­le­men­ta­tion of a deep ge­o­lo­gi­cal re­po­si­to­ry for Swe­dish nu­c­le­ar was­te. No other Swe­dish com­pa­ny has as much ex­per­ti­se re­la­ting to the links between hydro­lo­gy, che­mistry and ra­di­onu­c­li­des as Ge­o­sig­ma.

Our uni­que skills in ma­na­ging en­vi­ron­men­tal­ly ha­zar­dous was­te ha­ve de­ve­lo­ped, among other things, as a re­sult of our clo­se coo­pe­ra­tion with SKB (Swe­dish Nu­c­le­ar Fu­el and Was­te Ma­na­ge­ment Com­pa­ny). Our employ­e­es wor­king in the fi­eld of nu­c­le­ar was­te in­clu­de ge­ohydro­lo­gists, ge­o­lo­gists, fi­eld en­gi­ne­ers, che­mists and nu­c­le­ar che­mists. Se­ve­ral of our team mem­bers ha­ve PhDs and we ha­ve bro­ad range of skills within this area.

You can find out mo­re about so­me of the ser­vi­ces we of­fer in the are­as we spe­ci­a­li­se in.

Tra­cer tests

Ge­o­sig­ma has uni­que ex­per­ti­se in car­ry­ing out tra­cer tests af­ter th­ree deca­des of wor­king in a va­ri­e­ty of are­as in­vol­ving both rock and soil. By con­ti­nu­ously de­ve­lo­ping our skills, among other things as part of our work on a fi­nal re­po­si­to­ry for spent nu­c­le­ar fu­el, we ha­ve de­ve­lo­ped a le­vel of ca­pa­bi­li­ty which can be found in ve­ry few other com­pa­ni­es throughout the world.

In­ve­s­ti­ga­tions in­vol­ving tra­cers are used to sur­vey wa­ter flows or in­ve­s­ti­ga­te the trans­port pro­per­ti­es of con­ta­mi­na­tion, for ex­amp­le. By stu­dy­ing what hap­pens to the tra­cer, it is pos­sib­le to draw con­clu­sions about the sorp­tion or na­tu­ral de­com­po­si­tion of dif­fe­rent ty­pes of che­mi­cals. The­se in­ve­s­ti­ga­tions are car­ri­ed out in both ground­wa­ter and sur­fa­ce wa­ter.

One com­mon method used in ground­wa­ter in­ve­s­ti­ga­tions is to add a tra­cer at a cer­tain po­int and then ta­ke samp­les at another po­int. The sco­pe and the ob­jec­ti­ve of the tests can va­ry from simply con­fir­ming a su­spec­ted flow rou­te to qu­an­ti­fy­ing trans­port ti­mes and flows and eva­lu­a­ting che­mi­cal pro­ces­ses along the flow rou­tes.

Another wi­dely used pro­cess is the tra­cer di­lu­tion method. This ma­kes it pos­sib­le to me­a­su­re the mag­ni­tu­de of ground­wa­ter flow in si­tu.

So­me ex­amp­les of pro­jects whe­re tra­cer tests ha­ve play­ed an im­por­tant ro­le are as fol­lows:

• Trans­port pro­ces­ses in rock to be used for a fi­nal re­po­si­to­ry for spent nu­c­le­ar fu­el. A lar­ge num­ber of tests ha­ve been car­ri­ed out on behalf of SKB (Swe­dish Nu­c­le­ar Fu­el and Was­te Ma­na­ge­ment Com­pa­ny).
• Ar­ti­fi­ci­al in­filt­ra­tion of the wa­ter sup­ply, Tam­pe­re, Fin­land. Cli­ent Ta­va­se Oy.
• Qu­an­ti­fi­ca­tion of mass trans­port in ground­wa­ter con­ta­mi­na­ted with chlo­ri­na­ted hyd­rocar­bons on the si­te of a for­mer en­gi­ne­e­ring com­pa­ny (Bah­co in En­köp­ing). Cli­ent Pe­ab.

Bo­reho­le vi­de­os

Bo­reho­le vi­de­os are cur­rent­ly the best method of loca­ting and docu­men­ting fractu­res and other structu­res in bo­reho­les. When com­bi­ned with an eva­lu­a­tion of rock co­re samp­les, they al­low the pro­per­ti­es of the fractu­res to be as­ses­sed ef­fec­ti­vely.

Ge­o­sig­ma uses a vi­deo method cal­led BIPS, which is a uni­que, pa­ten­ted me­ans of re­p­re­sen­ting the en­ti­re wall of the bo­reho­le (through 360º). With the help of the BIPS image, the ope­ra­tor car­ri­es out a se­mi-au­to­ma­tic sur­vey, which al­lows the structu­res to be loca­ted and ori­en­ted. The ope­ra­tor me­a­su­res the si­ze of the fractu­res and then cha­rac­te­ri­ses them.

Sin­ce 1995, Ge­o­sig­ma has log­ged mo­re than 12,000 met­res of bo­reho­le in the nu­c­le­ar was­te sector on behalf of SKB (Swe­dish Nu­c­le­ar Fu­el and Was­te Ma­na­ge­ment Com­pa­ny). In the con­struc­tion and plant buil­ding sector, we ha­ve used BIPS on a num­ber of pro­jects on behalf of the Swe­dish Trans­port Ad­mi­nist­ra­tion. We ha­ve al­so worked on pro­jects in the mi­ning and po­wer in­du­stri­es.

Flow log­ging in bo­reho­les

Flow log­ging in bo­reho­les whi­le wa­ter is be­ing pum­ped out or in­jec­ted is a ti­me-sa­ving method of loca­ting wa­ter-be­a­ring fractu­res or fractu­re zo­nes and then as­ses­sing their ab­i­li­ty to trans­port wa­ter.

Ge­o­sig­ma has built a pie­ce of equip­ment for flow log­ging which can be used in bo­reho­les of dif­fe­rent di­a­me­ters. The flow is me­a­su­red in a test pro­be using a spin­ner (a pro­pel­ler with an electro­nic unit). The equip­ment is simp­le but ro­bust. A spe­ci­al se­a­ling unit al­lows flows to be log­ged in bo­reho­les in tun­nels.

The method is ide­al for de­ter­mi­ning the loca­tion and hyd­rau­lic pro­per­ti­es of wa­ter-be­a­ring structu­res around and un­der con­struc­tions in rock. It al­so al­lows a quick and ef­fec­ti­ve sur­vey of the in­flow po­ints in a bo­reho­le to be car­ri­ed out, in or­der to iso­la­te in­di­vi­du­al hyd­rau­lic con­ductors from one another be­fo­re car­ry­ing out mo­re in-depth stu­di­es of the pres­su­re and ground­wa­ter che­mistry, for ex­amp­le.

Ge­o­sig­ma has ex­ten­si­ve ex­pe­ri­en­ce of hydro­ge­o­lo­gi­cal in­ve­s­ti­ga­tions and can al­so car­ry out wa­ter loss me­a­su­re­ments, tra­cer tests, in­ter­fe­ren­ce tests and le­a­kage me­a­su­re­ments in tun­nels, for ex­amp­le.

So­me ex­amp­les of pro­jects whe­re we ha­ve used flow log­ging in bo­reho­les are as fol­lows:

• Pre­li­mi­na­ry in­ve­s­ti­ga­tions be­fo­re plan­ned mi­ning ac­ti­vi­ti­es in Pa­ja­la (Pöyry and SRK Con­sul­ting)
• Hyd­rau­lic cha­rac­te­ri­sa­tion of a lar­ge num­ber of per­cus­sion-dril­led in­ve­s­ti­ga­tion bo­reho­les (SKB (Swe­dish Nu­c­le­ar Fu­el and Was­te Ma­na­ge­ment Com­pa­ny))
• Flow log­ging in th­ree tun­nel bo­reho­les in Nor­ra Län­ken (the northern link) (Swe­dish Trans­port Ad­mi­nist­ra­tion)

Pum­ping tests in rock

Ge­o­sig­ma has ex­ten­si­ve, in-depth ex­pe­ri­en­ce of all ty­pes of pum­ping tests in rock. We spe­ci­a­li­se in eva­lu­a­ting and imp­le­men­ting pum­ping tests in rock. Our ex­per­ti­se is ba­sed on ye­ars of work on SKB’s (Swe­dish Nu­c­le­ar Fu­el and Was­te Ma­na­ge­ment Com­pa­ny) in­ve­s­ti­ga­tions in­to a si­te for sto­ring spent nu­c­le­ar fu­el in rock.

We imp­le­ment and in­ter­p­ret all ty­pes of pum­ping tests from simp­le pro­ces­ses in­vol­ving two or mo­re open bo­reho­les to mo­re sophis­ti­ca­ted tests in bo­reho­les with mul­tip­le pac­ker sys­tems. Pum­ping (or in­jec­tion) can ta­ke pla­ce in open bo­reho­les and in iso­la­ted sec­tions of ac­ti­ve bo­reho­les. The hyd­rau­lic con­di­tions in rock are ge­ne­ral­ly ex­t­re­mely he­te­ro­ge­ne­ous in dif­fe­rent direc­tions and at dif­fe­rent depths. Pum­ping tests can be used to es­ti­ma­te the hyd­rau­lic con­nec­ti­vi­ty in rock, iden­ti­fy hyd­rau­lic boun­da­ri­es within an area or stu­dy the hyd­rau­lic con­nec­tions between soil and rock.

The hyd­rau­lic pa­ra­me­ters are usu­al­ly in­ter­p­re­ted using mathe­ma­ti­cal mo­dels ba­sed on dif­fe­ring con­cep­tu­al as­sump­tions about the rock’s hyd­rau­lic pro­per­ti­es and do­mi­nant flow re­gi­mes.

Wa­ter loss me­a­su­re­ments

Wa­ter loss me­a­su­re­ments are per­for­med in bo­reho­les to mo­ni­tor the rock’s wa­ter-be­a­ring pro­per­ti­es. The re­sults can be used to as­sess how chang­es in the rock af­fect its sur­roun­dings, to es­ti­ma­te the amount of wa­ter flowing in­to tun­nels be­fo­re con­struc­tion work starts or to plan and mo­ni­tor grou­ting. Ge­o­sig­ma has de­ve­lo­ped a uni­que pie­ce of equip­ment for pre­li­mi­na­ry in­ve­s­ti­ga­tions in in­f­ra­structu­re pro­jects.

The Wa­ter In­jec­tion Con­trol­ler (WIC), de­sig­ned and built by Ge­o­sig­ma, gi­ves mo­re ac­cu­ra­te re­sults than ma­ny other con­ven­tio­nal in­stru­ments on the mar­ket. It has a mi­ni­mum flow of less than 2 mil­li­li­t­res per mi­nu­te, quick­ly re­aches a stab­le in­jec­tion pres­su­re and al­lows con­ti­nu­ous log­ging of pres­su­re and flow.

The me­a­su­re­ments are sto­red on se­pa­ra­te di­gi­tal me­dia. They can be used to eva­lu­a­te hyd­rau­lic con­duc­ti­vi­ty and this can be do­ne in two dif­fe­rent ways: either with the graph from the en­ti­re in­ve­s­ti­ga­tion (tran­si­ent eva­lu­a­tions) or with the fi­nal va­lue (sta­tio­na­ry eva­lu­a­tions). Tran­si­ent eva­lu­a­tions are pri­ma­rily used in are­as of low hyd­rau­lic con­duc­ti­vi­ty within the rock, whe­re sta­tio­na­ry con­di­tions can­not be ac­hi­e­ved in short tests.

Ex­amp­les of pro­jects whe­re Ge­o­sig­ma’s equip­ment has been used are:

• Stockholm Ci­ty Li­ne (Ci­ty­ba­nan)
• Stockholm by­pass

Ge­o­sig­ma has ex­ten­si­ve ex­pe­ri­en­ce of hydro­ge­o­lo­gi­cal in­ve­s­ti­ga­tions and can al­so car­ry out flow log­ging in bo­reho­les, tra­cer tes­ting, in­ter­fe­ren­ce tests and le­a­kage me­a­su­re­ments in tun­nels.