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A geotechnical and geochemical soil survey was carried out in the Olkiluoto nuclear waste disposal site as part of an overall site characterisation. Sedimentary cover (Quaternary deposit) in the study area was studied and sampled in 2 test pits dug by excavator. Standard procedures were applied in logging of physical properties including compactness, stone content, stone size, roundness and moisture. Following determinations and chemical analyses were carried out: anions (Br, Cl, F, N03 and S04); metals (AI, Ca, Cs, Fe, K, Mg, Na, Sr and U) from synthetic rainwater leach, humidity and organic mater content. F allowing geotechnical analyses were conducted: grain-size analysis (sieving, sedigraph) and permeability (K-value determination, constant head). This working report presents the all above analyses and shortly describes the results achieved.
OLKILUODON MAAPERANAYTTEIDEN ANALYSOINTI JA RAPORTOINTI
TIIVISTELMA
Geotekninen ja geokemiallinen maaperatutkimus tehtiin Olkiluodon tulevan loppusijoituspaikan ymparistossa osana alueen yleisempaa karakterisointia. Tutkimusalueen maapera tutkittiin ja maaperanaytteita otettiin 2 traktorikaivurilla kaivetusta koekuopasta. Koekuoppien maa-aineksen fysikaalisten ominaisuuksien, mm. maa-aineksen tiiveys, kivien maara, kivikoko ja kosteus, maarittamiseksi sovellettiin GTK:n vallitsevia standardikaytantoja. Naytteista tehtiin seuraavat kemialliset maaritykset ja analyysit: anionit (Br, Cl, F, N03 and S04); metallit (Al, Ca, Cs, Fe, K, Mg, Na, Sr ja U) synteettisesta sadevesiuutosta; kosteuden ja orgaanisen aineksen maaritys gravimetrisesti. Naytteista tehtiin myos raekokoanalyysi (seulonta ja sedigrafi) ja vedenlapaisevyyden maaritys. Tassa tyoraportissa esitetaan kaikki yo. analyysit j a maaritykset.
TABLE OF CONTENTS
ABSTRACT
TIIVISTELMA
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TABLE OF CONTENTS .............................................................................................. 1
Appendix 4. Chemical analyses ............................................................................... 29
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1 INTRODUCTION
This working report presents GTK's results of geotechnical and geochemical soil survey that was carried out in spring 2003 at the Olkiluoto nuclear waste disposal site as part of an overall site characterisation. The research activities were carried out based on Posiva's order number 9640/03/KIL (23.5.2003). Kimmo Lehto from Posiva acted as supervisor of this work.
2 FIELDWORK AND SAMPLING
Sedimentary cover (Quatemany deposit) in the study area was studied and sampled in 2 test pits, dug by excavator. The total number of the samples was 8 (Table 1 ). Standard procedures were applied in logging of physical properties including compactness, stone content, stone size, and moisture. These properties were estimated in the scale of 1 to 5, where 1 donates the smallest degree with respect to each property and 5 the largest (Kujansuu 1976). Description on stratigraphy, sediment properties and sample positions and codes were recorded in logging forms shown in Appendix 1. The logging system slightly modified after Hirvas & Nenonen (1990) were applied. Samples were taken by unpainted spade in order to avoid contamination. All samples were stored in temperature less than +6° C before analyses. Locations of the studied test pits are marked in Figure 1. Study pits, numbers 1-12, dug during previous phases of the geochemical and geotechnical survey also are also indicated in the map. Previous results (excluding study locations KK1- KK5) are reported in Posiva Working Report 2003-01 (Lintinen et al. 2003).
Table 1. Sampling locations, sampling depths and analyses carried out from Olkiluoto soil samples.
Sampling Sampling depth Geotechnical Chemical location analysis analysis KK 12 0-0.8 m X X KK 12 0.8-1.4m X X KK 12 1.4-2.1 m X X KK 13 0-0.4 m X X KK 13 0.4-1.5 m X X KK 13 1.5-2.6 m X X KK 13 2.6-3.7 m X X
KK 13 3.7-4.7 m X X
3 GEOTECHNICAL ANALYSES
Physical and geotechnical properties of 8 samples were determined including grainsize distribution, organic matter content, humidity and permeability. Analyses were performed at GTK's Geolaboratory except permeability, which was measured at J aakko Poyry Infra Geokeskus.
(uudet merkitty punaisella) RK1 e Raekokon:lytepiste
;:;,....-· ~ §·· ..... ~ .... 3 m ~
<:n <:n "' @ ~ <:n
~ 'J ~ 'J C1> C1> 00 0 "' 0 <Jl 0
0 0 0 0 0 0 0 0 0 0 0 0
3 3 3 3 3 3 m m m m m m ...
~rh
Figure 1. Soil sampling locations at Olkiluoto. Square: Test pit (new ones marked with blue), black point: grain-size sampling points.
w
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Analyses and techniques used were as follows:
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1. Organic matter content was determined gravimetrically by combusting the samples at 800 °C. (GTK's method code 8180).
2. Humidity was determined gravimetrically by drying the samples at 105 °C. (GTK's method code 8140)
3. Grain-size analysis of> 0,063 mm particles was carried out by dry-sieving the samples by Retsch mechanical sieve shaker. The sieves apertures used were 20 mm, 6,0 mm, 2mm, 0,60 mm 0, 20 mm and 0,063 mm (GTK's method code 657).Grain size analysis of < 0,063 mm particles was carried out by using Sedigraph 5000ET analyzer. Analysis included washing-and-screening of the samples and dry screening (GTK's method code 661). Results of sieving and sedigraph analysis were combined at 0,063 mm for grain-size distribution graph. The statistical parameters of the grain-size distribution were calculated by in-house computer programme by using the following equations:
MZ =(D10+D30+D50+D70+D90)/5 (1) where MZ = average grain size MZ (phi) = 2 based logarithm of grain size D = diameter D10, D30, etc =diameter, when percentage of passed material is 10, 30 etc.
DM 25, DM 50 and DM 75 are the quartiles of the distribution
4. Permeability analysis of the bulk samples, were performed by constant head technique (ASTM-standard Dis 084-90). The analysed samples consist of either till or sand packed on in test cell.
CHEMICAL ANALYSES
Altogether 8 soil samples were analysed at the Geolaboratory of GTK. The soil samples were dried at + 70° C and sieved to <2.0 mm fraction prior analyses. Easily soluble compounds were determined by extracting 2 hours with "synthetic rainwater", which consisted of a mixture of deionised water and HN03 having pH of 4.5.
Chemical analyses and techniques used were as follows:
1. Fluoride, chloride, bromide, nitrate and sulfate concentrations were determined from the water-leached samples by ion chromatography (Dionex DX120). The
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solid /solution-ratio used in the leach was 3 g I 30 ml. (GTK's method code 206I and 206R)
2. Metals from synthetic rainwater leach (GTK's method codes 217M and 217Pp) Aluminium, cesium, potassium, strontium and uranium concentrations were determined from the synthetic "rainwater" (2 hours, pH 4,5) leached samples by inductively coupled plasma- mass spectrometry (ICP-MS, Perkin Elmers Sciex Elan 6000). "Synthetic rainwater" consisted of a mixture of deionised water and HN03 having pH of 4.5. Calsium, iron, magnesium and sodium concentrations in the samples were determined by ICP-AES (Thermo Jarrel Ash IRIS Advantage).
5 UNCERTAINTY ESTIMATIONS
Detection limits and estimated uncertainties for analyses are shown in Table 2. Uncertainty estimations are based on analytical results of certified and other reference materials, replicate analyses of real samples and on interlaboratory test results. Uncertainty of grain-size distribution analysis and gravimetric determination of water and humus content was estimated from the measurement accuracy of analytical instruments, repeatability and reproducibility data given by supplier of analytical instruments and replicate analyses of real samples.
Uncertainties were calculated in 95 %confidence limit (z=2) by using equations:
Uncertainty of the measurement: B = z * U (1 ), where
z =factor which depends on the confidence limit= 2 U = combined uncertainty
2 2 [L ---~-~--~ ~-~----~-~---
U = V systematic +U random (2), where
Usystematic = Systematic error U random = Random error
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Table 2. Estimated uncertainties for analyses. 1Units are in mg/kg if not otherwise indicated. 2Relative uncertainty, expressed as% from the measured result marked.
Method Element or Detection Concentration U ncertainty2 Concentration Uncertainty2 code Determination limit range % range %
In the study area the sediment covering the bedrock is till. In some isolated depressions also fine-grained glacilacustrine sediments were observed in the study pits dug during the earlier phase of the study. The till cover smoothes the high amplitude bedrock undulations resulting a relatively flat surface topography. The thickness of the till cover is commonly 2-3 m. Typically the bedrock surface undulates in a short distance causing distinctive differences in the sediment thickness.
Till in the study area rests in many places on glacially striated bedrock surface. The till is massive or weakly laminated and it is rich in clay fraction. In study pits 12 and 13 (Figures 2. and 3.) the clay fraction (0 <0.002 mm) content of till varies from 7 to 12 %, whereas the fine fraction (0 <0.06 mm) content varies from 32 to 41 %. The permeability (K-value) of till varies from 10-7 to 10-9 m/s. The organic matter content of till is low, less than 1 ,2 %. The till in the study area can be described as basal till deposited by actively flowing basal conditions of ice sheet.
At both study localities, pits 12 and 13, the surficial (uppermost) sedimentary unit consist of coarse-grained littoral sand and gravel deposit from 0,4 to 0,8 m in thickness. The permeability (K-value) of the littoral deposit varies from 10-s to 10-6 m/s.
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The test pit descriptions and photographs (Figure 2 and 3) are presented in Appendix 1, results of the grain size analyses including statistical parameters in Appendix 2 and results of the permeability analyses in Appendix 3.
Figure 2. Test pit KK 12 at Olkiluoto
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Figure 3. Test pit KK 13 at Olkiluoto.
6.2 Soil chemistry
Results of the chemical analyses show similar trend related to the depth and soil type in the two studied test pits. Concentrations of the easily soluble anions and cations are lower in the uppermost sedimentary unit, which consists of littoral sand, comparing underlying till. The results reflect the natural leaching and surface absorption due to increasing fines and clay fraction content. Concentrations of the analysed cations and anions are in line with the results of the earlier phase of the study conducted in Olkiluoto (Lintinen et al. 2003). Results of the chemical analyses are presented in Appendix 4.
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7 REFERENCES
Hirvas, H, & Nenonen, K. 1990. Field methods for glacial indicator tracing . In: eds. R. Kujansuu & M. Saarnisto Glacial indicator tracing. Rotterdam: A. A. Balkema, 217-248.
Kujansuu, R. 1976. Glaciogeological survey for ore prospecting purposes in Northern Finland. In R.F. Legget (ed.), Glacial Till. Royal Society of Canada, Special Publication 12, Ottawa: 225-239.
Lintinen, P., Kahelin, H., Lindqvist, K. & Kaija, J. 2003. Soil sample analyses of Olkiluoto. Posiva Working Report 2003-01. 123 p.
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8 APPENDIXES
Appendix 1. Test pit logging forms.
Instruction for the test pit forms:
Physical properties are estimated in the scale of 1 to 5, where 1 donates the smallest degree with respect to each.
Mo denotes moisture: 1. Dry 2. Moist 3. Moderately wet 4. Extremely wet 5. Water running
Co denotes compactness: 1. Extremely loose 2. Loose 3. Normal 4. Compact 5. Extreme compact, concrete-like
St denotes stone content: 1. Stone less 2. Few stones 3. Normal 4. Abundant stones 5. Extremely abundant stones
Ssz denotes stone size: 1. Small stones, < 6 cm 2. Large stones, 6-20 cm 3. Small boulders, 20-60 cm 4. Boulders, 60-200 cm 5. Large boulders, > 200 cm
Geological Survey of Samples Lithology
Finland ................................... ··········
QuatemiD straigraQhy
Field work: Posiva Oy
Study location: Olkiluoto lo-0.8 m Gravel
Map sheet: 1132 ········· ············································· 10.8-0.4 m
···································· I Till
Position: X: 6791.803 Y: 1525.833 IZ:8.0 m
. ········································
!Number of study locality: KK 12 l.4-2.1 m
Method of investigation: Bedrock
Test pit
Depth of groundwater surface: 1.8 m
Photographs: Figure 2
!Notes:
...................................
Mo Co St Ssz Colour
13 14 12 2 Grey
3 4 2 2 Grey
m Droving
1
2
3
4
5
Description
<::;g<y_S.~ .. ~~~9.~l:ll ... ~~P9.S.i~ .....
Massive till
Massive till Bedrock: diabase with
gr.~~!~~p~g~l:}~~~-~--~-i~~····
1--"
1--"
Geological Survey of tSamples, I ILithology IMo Ieo 1St 'Ssz I Colour I m' Droving IDescription I Finland
Quaternary straigraphy ·' IO:Q4~11 J ..••.••.••............... ! ... J .. · ]GIOVOi .............. • l t l:
Field work: Posiva Oy ···t·· ··•·
Study location: Olkiluoto
IMap sheet: 1132 r •1 T : r : Jfiij 13 jJ j2 ... J.2. JGrey 1
Position: 0.4-l.S m
X: 6791.769 Y: 1525.898 lz:8 m
IN umber of study locality: KK 13
Method of investigation: Test pit
+·····•···
·loepth of groundwater surface: r~-~·~~-l : . J I : ~~Ill. ·]~ lj 2 [Grey
Photographs: Figure 3
!Notes:
12:6=i7 m Till 2 Grey ..........
13.7-4.7m Till 12 rrey
~~.':ll:~~--~i.J!<?r.C1~ .. 4~P~.s.~t ....... .
·Mass"i~e-tiif ..
2
Massi~etiii····
3
Mass·i'~e-ti!I····
4
Massi~e-tiii'. ··
I 5
~
N
Appendix 2. Grain size distribution and statistical analyses of soil (Quaternary deposit) samples from Olkiluoto. The analysis methods have been described in the text.
2003 LAB0000097 mm % KK12 0-8 20.0 100.0 MZ(PHI) -0.886 Order 80427 L03043831