MASS STABILIZATION of. peat, mud and contaminated sediments. Geoteknikerdag Juni 1st & 2nd 2007 Mikko Leppänen & Jorma Havukainen Ramboll Finland Oy

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1 MASS STABILIZATION of peat, mud and contaminated sediments Ramboll Finland Oy

2 Principle of the mass stabilization method Embankment Geotextile Torv Peat/ mud/ clay Sand/Morän Sand/Moraine Mass stabilized peat/mud/clay 2

3 Principle of the mass stabilization method combined with column stabilization Embankment Geotextile Peat Masstabilized stabised peat peat Torv Clay Columns in clay Moraine 3

4 Principle of the mass stabilization method method Binder tank Mass stabilization machine Mixing tool Mass stabilized peat, mud or clay Peat, mud, clay m Work direction m Geotextile Compaction embankment (h ~1.0 m) 4

5 Mass stabilization- Main purposes Increase soil strength Improve deformation properties Remediate contaminated soil Save costs (transportation of masses etc) Save disposal areas Save natural aggregates and rock ballast 5

6 Equipment for mass stabilisation 6

7 Equipment for mass stabilisation ALLU-mass stabilisation unit from Ideachip 7

8 Binder technology Binders to be used shall be tested beforehand in laboratory (and in field) 8

9 The Importance of Laboratory Tests Stabilizers: Lime Cement Lime-cement Aggregates Industrial by-products (fly ash, blast furnace slag, FGD-residue etc.) Technical, economical and environmental optimizing by careful binder tayloring 9

10 Typical binders for mass stabilisation (for mud, peat, sediment) Soil type Binder Typical amount Mud Cement 100% Cement+industrial by products kg/m3 Peat Cement 100 % Cement+industrial by products kg/m3 Sediment Cement Cement+industrial by products kg/m3 10

11 Example of laboratory test with binders kpa (compression strength 28 days) ,5 m 3,5-5,5 m 5,5-8,5 m Peat Clay 1 Clay 2 Depth BINDER 1 BINDER 2 11

12 Temperature affects the process kpa after 14 days Binder 1 Binder 2 Binder C +8 C +12 C +18 C +25 C 12

13 The Trial embankment of Veittostensuo, Finland Mass stabilization of peat and column stabilization of clay, Mass stabilization of peat ~ 500 m 3 (Objective final strength 50 kpa) - Column stabilization of clay ~ m ~1,5 m ~3 m - W natural (peat) ~ % - Shear strength 5 10 kpa kpa (30 d) - Settlements (Stabilized (peat+clay) 0,25 0,4 m in 6 years m - W natural (clay) ~ % 13

14 The settlement observations at Veittostensuo trial embankment (~ 8 years) VEITTOSTENSUO TEST EMBANKMENT, FINLAND SETTLEMENT OBSERVATIONS ( ) Time t, days Settlement S, m 0,1 0,2 0,3 0,4 Settlement plates : Plate 1 Plate 2 Plate 3 Plate 4 0,5 04/1993 h = 0,5 m 05/1993 h = 1,5 m 04/1994 h = 2,5 m 03/1995 h = 1,5 m Plate 5 Plate 6 14

15 Mass stabilization of peat, Road 601 Sundsvägen, Råneå, Northern Sweden, Mass stabization of peat ~ m 3 (700 m) 100 Shear strength (kpa) days 30 days 0 mix kg/m3 mix kg/m3 mix kg/m3 mix kg/m3 mix kg/m3 mix kg/m3 An example of stabilization test results with peat Objective final strength in field 50 kpa - W natural peat ~ 620 % (1 1,5 m layer) - Shear strength 7 kpa kpa (30 d) - Settlements (Stabilized peat) 0,05 0,2 m in 4 years 15

16 Mass stabilization of peat, Road 601 Sundsvägen, Råneå, Northern Sweden, 1995 BEFORE STABILISATION MASS STABILISATION ONGOING ROAD IN USE 16

17 Railway track, North of Stockholm, Sweden,

18 Road 45 in Northern Sweden, 1998 New road Existing road Peat Peat Mass stabilisation Tid, dygn Sättning, m ,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 pegel 7, V 1100 pegel 4, H

19 Road 32 in Central Sweden, 2002 PROFILE Torv Peat Masstabiliserad stabilized peat torv Torv Peat 19

20 New railroad between Helsinki and Lahti Peat has been mass stabilized in order to make a firm bed for embankment piling Area: Area ca. 40 m x 300 m 2 Depth max. 5 m Volume ca m3 20

21 New railroad between Helsinki and Lahti 21

22 Port of Hamina in Eastern Finland CONDITIONS IN THE BEGINNING OF THE WORK MASS STABILIZATION ONGOING MASSTABILIZED HARBOUR AREA WITH PRELOADING 22

23 Sörnäinen Strand in Helsinki,

24 Sornäinen Strand in Helsinki,

25 Port of Trondheim in Central Norway 25

26 Port of Trondheim in Central Norway Dredging work ongoing 26

27 Port of Trondheim in Central Norway Mass stabilisation ongoing 27

28 Port of Trondheim in Central Norway 28

29 Valencia in Spain Mass stabilisation for a container area is ongoing 29

30 Valencia in Spain 30

31 Road for evacuation in Florida The existing road shall be widened to four lanes Area: Length 14,4 km Breath m Depth max. 4 m 31

32 Road for evacuation in Florida 32

33 New Harbour in Vuosaari 2008, Helsinki 33

34 New Harbour in Vuosaari, Helsinki Layout Stabilization area of Rice Field in

35 Vuosaari Harbour, Stabilization of Rice Field in 2004 The biggest deepstabilization project in Finland until 2004 Total area ~ 9 hectars Column stabilization ~ 70% Mass stabilization ~ 30% Total volume ~ m 3 (columns ~ sediment-m 3 and masstabilization ~ sediment-m 3 ). Binding agent was cement by Finnsement (CEM II/A-M (S-LL) 42,5 N) Contractor was YIT Rakennus Oy and geotechnical planning was made by Ramboll Finland Oy. 35

36 Vuosaari Harbour, Stabilization of Rice Field, 2004 Before and after 36

37 Vuosaari Harbour, Stabilization of Rice Field,

38 Vuosaari Harbour, Mass stabilization of TBTsediment, Test basin Sedimentlagoons 38

39 Vuosaari Harbour, Mass stabilization of TBTsediment, The biggest mass stabilization project in Finland until 2006 Total area ~ 11 hectars Mean depth was 5 m Total volume ~ m3 Binding agent was cement by Finnsement (CEM II/A-M (S-LL) 42,5 N); 135 kg/sediment-m3; total ~ tons 39

40 Vuosaari Harbour, Mass stabilization of TBTsediment, Test basin

41 Vuosaari Harbour, Mass stabilization of TBT-sediment, Principle of the mass stabilized construction 41

42 Vuosaari Harbour, Mass stabilization of TBTsediment,

43 Vuosaari Harbour, Mass stabilization of TBTsediment, Mass stabilization equipments Geotechnical planning was made by Ramboll Finland Oy. Contractor was Hyvinkään Tieluiska Oy The feeding and mixing of cement was carried out by two units (7 000 kg/hour) The whole area was diveded in blocks (20 m 2 /5 m); 13 tons of cement was mixed in each block in 2 hours Target 90 day shear sthrength 70 kpa (min) 43

44 Vuosaari Harbour, Mass stabilization of TBTsediment, The mixing device 44

45 Vuosaari Harbour, Mass stabilization of TBTsediment, stability ok Extra overloading 3 m (Tot 140 kpa) Areal overloading 2 m (Tot 90 kpa) Additional preloading 1,5 2,5 m to final level) Primary preloading layer 1 m Mass stabilized TBT-sediment 45

46 Vuosaari Harbour, Mass stabilization of TBT-sediment, , Test sounding points of lagoon A1 (14, 28 and 90 days) ~ 4,3 hectars, ~ m 3 14 d/70 points 28 d/35 points 90 d/20 points 46

47 Vuosaari Harbour, Mass stabilization of TBT-sediment, , Test soundings of lagoon A1 After 14 days Group I (23 points) Group II (23 points) 60 kpa 60 kpa Ryhmä II (24 points) 14 d soundings; shear strength (average) Target 60 kpa 60 kpa 47

48 Vuosaari Harbour, Mass stabilization of TBTsediment, Settlement observations at lagoon A1 Observing date of settlement plates (PL 1 8), Lagoon A Not measured before Settlement, mm PL1 PL 2 PL 3 PL 4 PL 5 PL 6 PL 7 PL 8 48

49 Removal of tributyltin (TBT) from the seabed in Vuosaari Harbour, Helsinki, Finland Summary 98,8 % (96,5 kg) of TBT was removed from the seabed and transferred to the Niinilahti filling area The contaminated sediment (~ m3) was mass stabilized and utilized as harbour field structure The costs of the TBT removal and stabilization process was ~10,5 million euros The removal of TBT was a seamless part of the construction work and Vuosaari Harbour will be operative in the end of

50 CONCLUSION: Stabilisation is a solution for many soft soil problems 50

51 Thank You! 51