Presentation by Jan-Willem Meertens and Bert de Doelder (Gemeentewerken Rotterdam) at the iMOD International User Day, during Delft Software Days - Edition 2017. Tuesday, 31 October 2017, Delft.

1. Using iMOD in the
Rotterdam port
area, as part of
the groundwater
management
system
Jan-Willem Meertens/Bert de Doelder
October 31st 2017
- groundwater management
- contaminant transport model
- exchange experiences

2. 5-12-2017
Hydrological site model
anthropogenic soil layer
+4,5 m
-1 m
-20 m
-45 m
holocene (aquitard:
layered sand/clay/peat)
1th pleistocene aquifer
(coarse sand)
loam layer (discontinuous?)
2th pleistocene aquifer
(fine sand)
groundwater flow into surrounding polders
(reclaimed land) via pleistocene aquifer
- 60 m

3. Common ground:
•sustainable soil management (PPP) in an industrial environment.
Municipality of Rotterdam:
•reliable soil contamination assessment
•reliable risk-assessment and mitigation strategy
•no soil risks for municipalities, surrounding the Rotterdam Port area
Port of Rotterdam:
•cost-effective approach
Companies:
•clear-cut obligations, lower costs
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Objectives

4. Soil contamination should not leave the Port area !
(model assessment: feasable ambition)
In due time:
• stable end situation
• within groundwater
management area, e.g. city limits
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Ambitions

5. Source mitigation strategy
Difficult soil situation in the dutch delta area
Source removal in combination with “Natural Attenuation” (NA)
 soil quality improvement short and long term
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6. 5-12-2017
Source mitigation in practice
Source removal in holecene layer is not cost-effective !
1th pleistocene aquifer
20 - 35 m - sand, high permeability
2th pleistocene aquifer
40-60(?) m - sand, high permeability
Holocene
5 - 20 m - clay/peat/sand,
layered, low permeability
levelled-up 0 - 5 m - fine sand
Separating layer some m’s - loam
“impermeable” = gray  brown  light brown  orange  yellow  light yellow = permeable

7. (Long term) mitigation effect is assessed with an imod groundwater
model
Site-specific approach is needed:
•different contaminants
•local soil structure
•buildings, installations and underground infrastructuur
•site location, e.g. distance from management area limit
•etc.
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Source mitigation site-specific

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Results contaminant transport modelling
low bio degradation rate
average bio degradation rate
low bio degradation rate and source removal

9. In the port area contaminant transport is extremely slowly.
Short term monitoring is often used but less useful.
Long term predictions are difficult but nessesary.
Modelling has to be combined with 20 years of 5 yearly monitoring
(Instead of 5 years of yearly monitoring to investigate a stable situation )
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Lessons learned

10. As Visual MODFLOW users at first we experienced iMOD as rather
user unfriendly
With time iMOD turned out tot be very useful:
•1 model instead of several sub models
• An advantage but not always
as
• Regional model can be too rough to use as local sub-model
•Logical, flexible
•Quick 3D-visualisation
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Experiences with iMOD

11. Deltares developed the MODFLOW/SEAWAT model of the Rotterdam
port area using iMOD.
How to validate a regional model for using as a local sub-model
We are very curious about experiences of other users.
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Discussion