The International Committee on Contaminated Land Management of Groundwater Quality in the Netherlands co.molenaar@rws.nl margot.de.cleen@rws.nl Copenhagen, 4-5 October 2017

October 2017■ Copenhagen, Denmark■ www..iccl.ch Outline Characteristics of the Netherlands Characteristics of soil and groundwater policy in the Netherlands Area-oriented approach of the plumes An example: the Rotterdam harbour Conclusion October 2017■ Copenhagen, Denmark■ www..iccl.ch

Characteristics of the Netherlands Delta of 4 internationals rivers Soil: fine sediment of clay, sand and peat. Multi layered. Shallow groundwaterlevels. Groundwater flows. Fresh water aquifers up to depth 700 meter, salt water aquifers up to depth of 900 meter +/- 50% drinking water from groundwater resources October 2017■ Copenhagen, Denmark■ www..iccl.ch

Characteristics of the Netherlands The Netherlands without dikes Cooperation: the polder model, a cultural aspect in the fight against water October 2017■ Copenhagen, Denmark■ www..iccl.ch

Characteristics of the Netherlands Fresh water aquifers up to depth 700 meter, salt water aquifers up to depth of 900 meter. October 2017■ Copenhagen, Denmark■ www..iccl.ch

Soil and groundwater policy (1) Policy development since 1980’s after emerging site Lekkerkerk Policy development: From multifunctional to risk based fit for use approach. Owner of a site has the obligation to remediate Distinction between new and historical contamination (1987) Groundwater is included in definition contaminated site and part of soil legislation Soil quality must comply with the current or future use Policy goal is to reuse as much soil as possible 41 competent authorities for remediation 425 municipalities have a soil policy (excavated soils) October 2017■ Copenhagen, Denmark■ www..iccl.ch

Soil and groundwater policy (2) Growing interest of using subsoil (energy, climate, water, spatial planning) Remediation in the most sustainable and cost effective way Presently focus on historical contamination with unacceptable risks Towards a new environmental and spacial planning law where development determines the moment of remediation Sustainable land management! October 2017■ Copenhagen, Denmark■ www..iccl.ch

Remediation policy: focus on sites with unacceptable risks Period 2009-2015  unacceptable human risks Period 2015-2020  unacceptable risks for the groundwater and ecology End result of inventory: 400 human health 1400 migration to groundwater 200 ecology October 2017■ Copenhagen, Denmark■ www..iccl.ch

Urgent sites migration to groundwater Historic contamination: the pollution originated before 1987 The quality of the groundwater exceeds the intervention values for groundwater The volume of affected groundwater is over 6.000 m3 and the annual increase in volume is over 1.000 m3 There is a layer of contaminants on top or below the aquifer Relation to vulnerable objects, defined according to the source-path-receptor model (water supply for human consumption, process water for industry or a protected area in accordance with the EU Water Framework Directory) October 2017■ Copenhagen, Denmark■ www..iccl.ch

Urgent sites migration to groundwater (2) For the 1400 locations Competent authorities: Start of remediation before 2020 Integrated area-oriented approach of the plumes Stimulate private owners to remediate their sites (source) October 2017■ Copenhagen, Denmark■ www..iccl.ch

October 2017■ Copenhagen, Denmark■ www..iccl.ch Single plume; single owner => liability and responsibility is straight forward October 2017■ Copenhagen, Denmark■ www..iccl.ch

Urban inner city reality => source liability is clear, but who takes care of the plumes? Drinking water extraction Parking garage Metro tunnels ATES Multi party monitoring of intermingled plumes

Bottlenecks for remediation of groundwater plumes urban areas often contain large mixed plumes who is liable? often no technical or cost effective solution available, since plumes are located under city centers therefore there is no incentive to remediate these sites dispersion of the contamination is influenced by other functions of the subsoil municipalities want to make an integrated comparative assessment by developing an urban area. a change in addressing the liability is needed an incentive is needed to reach the policy goal October 2017■ Copenhagen, Denmark■ www..iccl.ch

Area oriented approach Integrated management and monitoring 13

October 2017■ Copenhagen, Denmark■ www..iccl.ch Solutions 1. Owner disconnect source from plume the owner has to remediate the source by existing legislation transfer the liability for the plumes to a public organization owner sells the plume (redemption money) and is no longer liable October 2017■ Copenhagen, Denmark■ www..iccl.ch

Solutions 2. Public organization Government is responsible for groundwater and has the instruments to organize an area oriented approach For the mixed plumes up scaling to an area is needed Competent authority has to make a (management) plan => including the permissible value of the contamination on the borders (target values, intervention values, …) Public consultation is obliged Financial agreements: Urban (re)development is mostly the driver so other stakeholders have an interest area oriented approach October 2017■ Copenhagen, Denmark■ www..iccl.ch

Area-oriented approach of the plumes Define the total area Only for historic contamination!! Contamination originating after 1987 must be remediated directly by polluter Risk management in stead of remediation on an area level Monitoring on the border of the area and if necessary take remediation measures at borders or plane of compliance (poc) Dispersion within the area is allowed; the quality of the groundwater must comply with the functions of the subsoil reduces costs 50% (average) October 2017■ Copenhagen, Denmark■ www..iccl.ch

An Example: the Rotterdam Harbour October 2017■ Copenhagen, Denmark■ www..iccl.ch

An Example: the Rotterdam Harbour (2) October 2017■ Copenhagen, Denmark■ www..iccl.ch

October 2017■ Copenhagen, Denmark■ www..iccl.ch Conceptual Model October 2017■ Copenhagen, Denmark■ www..iccl.ch

October 2017■ Copenhagen, Denmark■ www..iccl.ch Conceptual Site Model Contaminant distribution Availability of representative field data (from databases and industry) Priority contaminants Related to industrial activities Geohydrology Regional scale Complex soil stratification Influence of heterogeneities (sand piles, groundwater extractions) Natural attenuation Very important for long travelling times Redox conditions Biodegradation rates from representative field studies Modeling of future impacts at receptors (Monte-Carlo) October 2017■ Copenhagen, Denmark■ www..iccl.ch

October 2017■ Copenhagen, Denmark■ www..iccl.ch 3rd plane of compliance October 2017■ Copenhagen, Denmark■ www..iccl.ch

3rd plane of compliance (2) October 2017■ Copenhagen, Denmark■ www..iccl.ch

Result risk assessment Impact to surface water (1st plane of compliance): contaminant flux from the groundwater is small compared to other emission sources concentration within the surface water remains well below norms Impact to aquifer (2nd plane of compliance) already considerable (8% of the aquifer impacted) and gradually increasing (to 12% in 2040) aquifer has limited use (brackish to salt water) Impact to adjacent groundwater systems (3rd plane of compliance) relatively limited now (3% of the border impacted) but strongly increasing (to 8% in 2030 and 10% in 2050) October 2017■ Copenhagen, Denmark■ www..iccl.ch

October 2017■ Copenhagen, Denmark■ www..iccl.ch

October 2017■ Copenhagen, Denmark■ www..iccl.ch Conclusions Advantages of area oriented approach Protection of residential area and farms Use of natural resilience Optimization of monitoring Cost-effective Modeling gives insight in risks and measures Area oriented approach is a cost effective and sustainable way of risk based management! October 2017■ Copenhagen, Denmark■ www..iccl.ch