Handling of Dredged Material in the Netherlands H.P. Laboyrie M.Sc. Eng (C.E. Delft)

Transcription

1 Handling of Dredged Material in the Netherlands H.P. Laboyrie M.Sc. Eng (C.E. Delft) Head Environmental Department Civil Engineering Division Dutch Ministry of Transport, Public Works and Water Management

2 Contents Introduction Situation in the Netherlands Overview on treatment and disposal options Dutch policy on treatment and disposal Conclusions and recommendations 2

3 Introduction Frequent dredging necessary in delta area Reasons for dredging Shipping Water discharge Environment Large amounts of DM Mm3/yr Mainly from maintenance dredging mainport Rotterdam 3

4 Present destinations treatment and reuse 2% disposal 15% relocation on land 17% relocation in sea 66% 4

5 Problems with destinations for DM Relocation at sea (90%): environmental restraints Relocation on land (30%): lack of space and acceptance Treatment: expensive, small scale, no market for products New CDF s : Nimby Destinations for DM become more scarce and more expensive Largest problem DM from fresh waters especially in 5 urban areas

6 6

7 Ripening fields and sedimentation basins near CDF Slufter 7

8 Technically feasible treatment chains ) disposal depot/cdf 3 2) ripening and landfarming soil 2 3 3) sand- separation silt fraction coarse (sand) fraction depot or treatment sand ) dewatering stabilization aggregate soil silt fraction ) art. gravel, art. basalt, bricks, etc. thermal immobilization coarse (sand) fraction sand available for the following types of DM (grain sizes, contamination) 1 fine, cocktail 2 (moderately) sandy, cocktail 3 (moderately) sandy, PAK/oil 8

9 Techniques Simple techniques Sandseparation/ripening/landfarming/bioremediation/ chemical immobilisation or stabilisation restricted use depending on qualities CDM, standards for building materials and market Advanced techniques: thermal immobilisation after pretreatment also for heavily contaminated DM 9

10 Simple techniques 10

11 Thermal immobilisation 11

12 average cost in /m3 subaquatic disposal sand separation incl. disposal ripening/land farming stabilization thermal immobilization

13 Problem analysis of treatment Treatment up to now very limited and small-scale higher costs of treatment compared with disposal no guaranteed or continuous supply for treatment to justify the high investments lack of market for products as secondary raw materials limitations for beneficial use due to standards for the products 13

14 R&D on treatment and disposal Conclusion for Dutch policy 1998: Only sand separation is feasible Confined disposal is a environmental sound solution: several large CDF s were planned 14

15 Developments Public resistance against new CDF s (NIMBY) Private sector: Lobby for treatment Political pressure to carry out a pilot project on large scale treatment National survey of feasible techniques and costs by AKWA in close co-operation with the private sector 15

16 Outcome of national survey Treatment is in general more expensive than disposal More treatment should not be at the expense of dredging More treatment means that more budget is needed Highest efficiency with simple treatment in combination with disposal If thermal immobilization is introduced then for hot spots Treatment of all DM is too expensive; disposal remains necessary 16

17 Political decisions Dutch policy is aimed at more treatment based on less disposal production of building materials More budget for treatment of CDM during test period of 4 years Confined disposal (and CDF s) remain necessary (in combination with treatment) Ultimate goal is a structural reversal to more treatment if the test period is succesful 17

18 Extra budget 73 million 32 million: pilot project for treatment 41 million: Subsidy for treatment 18

19 Policy instruments to stimulate treatment Subsidy for treatment of CDM Environmental tax on the disposal of treatable DM (at the moment DM >60% sand) Creation of markets for products from treatment adaptation of legislation on building materials application of products in governmental projects 19

20 Interrelation policy instruments Degree of contamionation Class 4 Class 3 Class 2 Subsidy for treatment Adapting Build.Act, stimulation sale, creation of markets Environmental tax on disposal 0% 60% Sandpercentage 100% 20

21 Conclusions for the Netherlands Treatment of CDM is a political goal in order to reduce disposal and produce building materials Dutch policy measures are taken to promote treatment during a test period of 4 years It is now up to the private sector to take the opportunities and demonstrate that treatment is feasible Future decisions depend on the results of the test period 21

22 General conclusions Source control is a needed to reach a sediment quality in the future, which does not pose a risk to aquatic systems or upland use. In the meantime, treatment and confined disposal remain necessary Investment in source control upstream is often more economical than treatment downstream If the higher costs for treatment are not compensated this may lead to less dredging Confined disposal will remain a necessary option 22

23 General recommendations An adequate legal framework for the handling of sediments is needed (basis EWFD) If treatment is the political goal consider (temporary) financial impulse increase of budgets for dredging to compensate for the higher costs of treatment create markets for products of treatment adaptation of legislation for beneficial use 23