© 2012 ISCOWA and SGI. All rights reserved.
CPR: From material emission data to a life cycle perspective
Pascal SUER1, Ola WIK1 and Martin ERLANDSSON2
1SGI Swedish Geotechnical Institute, 58193 Linköping, Sweden, pascal.suer@swedgeo.se, ola.wik@swedgeo.se
2IVL Swedish Environmental Institute, martin.erlandsson@ivl.se
Abstract
The European Construction Products Regulation (CPR, 305/2011/EU) requires environmental assessment of construction works, but performance data (CE-marking) are of construction products.
Both environmental risk assessment (ERA) and life cycle assessment (LCA) need to derive emissions from construction works from harmonised tests on products. Several European countries use national assessment schemes with models of construction works, in order to calculate ERA limit values for construction products.
We summarise a number of European construction work ERA schemes for emissions to soil and water. A typical construction works model scenario is a paved road or parking lot, 1m high, with 300 mm/a infiltration and emissions to the groundwater. The scenarios ranged from an infinite bare fill layer through a walking path to an enclosed material inside a road. Water movement modelling ranged from as “batch test” to detailed hydraulic modelling.
It seems desirable to have several scenarios for the intended use of construction products in ERA and LCA. This paper shows several examples of existing scenarios, but more work will be needed to find a coherent framework for assessment of emissions from construction works with greater harmonisation.
Keywords: Risk assessment; Life cycle assessment LCA; Leaching; Construction works; Construction products regulation;
Figure 1. A general structure of the assessment of environmental impact from leaching. The circle shows the subject of the paper.
Figure 2. Substances, processes and compartments, an interpretation of BWR 3 of the CPR
Test data for product
•Scenarios of intended use
Release from construction
works
•Scenarios for transport in soil and water
Concentration prediction at
POC
•Exposure
scenarios Risk to human health and environment
1 Introduction – towards a harmonised construction
In 2011, the European parliament and council accepted the construction product regulation (CPR, 305/2011/EU). The CPR comes into full force in 2013. Many requirements for CE-marking based on the CPR will still be set at a national level. The background for many environmental requirements will be basic works requirement 3 (BWR3). BWR3 is particularly concerned with emissions of substances that damage the environment and human health.
A limit to the emission of dangerous substances from construction products is an example of a requirement that can be made by European countries. Harmonised European methods to measure these emissions are forthcoming. Methods to calculate the damage to the environment and human health from these emissions vary between countries. There is a general conceptual model for environmental risk assessment (ERA) (see for example Figure 1), but there are differences in the intended use, the soil and water transport model, and the exposure scenarios.
The CPR also sets a life cycle perspective in BWR3. Climate-affecting gases are mentioned as relevant emissions, and the impacts from construction, demolition and waste management are considered in addition to the impact of the use of construction products. European method EN 15804 will support the life cycle approach. An environmental product declaration based on EN15804 is a building block for life cycle assessment (LCA) for construction works. Unfortunately, ecotoxicity and human health are not included as environmental default indicators in the current version of EN15804.
A basic challenge to include toxicity is the calculation of emissions from constructions from measurements on products. Here LCA faces the same problems as ERA for the scenarios of intended use. The scenarios and methods to calculate the release of substances from constructions could be equivalent for ERA and LCA.
It is hard to conceive of common criteria that can protect the environment, especially the groundwater, throughout Europe. Climate, soil properties, background levels of substances in the environment, cultural usages etc. are important factors that vary a lot between locations. Differences will be necessary, but perhaps unnecessary differences may be avoided. A harmonised approach for the structural design of buildings and other civil and engineering works has been introduced through a series of European Standards, the Eurocodes. Development of a harmonised approach for ERA and LCA for construction products is an interesting opportunity in the CPR
This paper concerns the intended use scenarios of construction works used for legislation in several European countries. The scenarios concern the outdoor emissions of construction products in construction works, with a focus on leaching. The scenarios are regarded in the light of BWR 3 of the CPR and a life cycle perspective.
2 Materials and methods – the background to guidelines and limit values
Limit values and guidance values for use of materials in constructions have been collected from Belgium (Flanders region), Denmark, France, Germany, the Netherlands and Sweden. We selected these countries because their limit values are ERA-based and their intended use scenarios are accessible and reasonably transparent. For Flanders, France (general guidelines), Germany, the Netherlands and Sweden, there is a published ERA available. For Denmark and France (bottom ash legislation), this background is less clear, and the conditions for use set in the legislation are used in this study. At the time of writing, Austria and the Czech Republic accepted reuse of materials that fulfilled the criteria for the acceptance of waste at a landfill for inert waste (waste acceptance criteria, WAC) (Lebensministerium, 2011)(Hjelmar, 2011). Also Finland, with some adjustments, used the WAC (Government Decree, 2006).
Note that limit values may have changed from those calculated with the scenarios. We focus on the
We first set the legislation in a general context: the legal standing of the regulation and the materials it was intended for. Then we compare to the CPR, specifically to BWR 3, which is particularly concerned with effects on environment and human health. Figure 2 is a graphical interpretation of the substances, processes and compartments that receive substances, mentioned in BWR 3. Compartments like soil, groundwater and marine water are also important for LCA: current attempts to handle human and ecotoxicity assign emissions from products to a specific compartment, and calculate toxicity- related damage for emissions into each compartment. Finally, we proceed to the dimensions and characteristics of the construction works themselves.
3 Results – context, BWR3 and design of the construction works
3.1 The context of the limit/guideline values
Most of the scenarios come from the calculation of limit values that have legislative force (Table 1).
For example, Belgian (Flanders region) and Dutch limit values are from laws on waste and soil quality respectively. In some countries, laws for specific materials complement guidelines for all materials.
An example is France, with a law for use of bottom ash in roads (Arrêté du 18/11/11) and general guidance on alternative materials (Chateau, et al., 2011). Denmark also has a law for bottom ash and certain other materials, but lacks published general guidance. The Swedish values are at the end of this spectrum. They provide guidance; the Swedish legislation has no limit values (Table 1).
The Dutch limit value is the same for all stony construction materials (Table 1). No difference is made between pristine materials and waste. The Swedish guidance also has the same values for all materials, but the guidance values are only intended for waste. On the other hand, Germany‟s upcoming recycling decree specifies limit values for each substance and each material separately.
The intended use of the materials also differs considerably. The Swedish general guidance and Danish category 1 are for any construction works. The other Danish categories, as well as German and French limit values, are for road-related constructions and landscaping. 43 road- and railroad-related constructions have been specified in detail in the upcoming German recycling decree. The applicability of each material in each construction in different hydrological circumstances is defined (ErsatzbaustoffV, 2011). The Dutch legislation has covered the construction sector with general construction works: granular material, bound material, and a well-isolated application for materials that leach dangerous substances (Figure 4).
3.2 The scenarios, the CPR BWR3 and LCA
“The construction works must be designed and built in such a way that they will, throughout their life cycle, not be a threat to the hygiene or health and safety of workers, occupants or neighbours, nor have an exceedingly high impact, over their entire life cycle, on the environmental quality or on the climate during their construction, use and demolition, in particular as a result of any of the following: …” (BWR3 of the CPR, 305/2011/EU).
The „following‟ mentioned above is illustrated in Figure 2, and how the studied limit values relate to these requirements is summarised in Table 2. All except the EU landfill scenario are for the use phase of the life cycle. All the studied scenarios are created for ERA. They generally protect environmental quality and sometimes neighbours or occupants. Workers health and climate change are not included.
Table 1. Characteristics of the legislation or guidelines for use and reuse of aggregates discussed in this study.
Context Materials Use
Country Identifyer Legislation Guidellines Stony materials Soils and sediments Recycled construction waste Waste Alternative materials MSWI-BA Other ashes Polluted soil Free use in constructions Soil /backfill Landscaping Road Road-related construction In surface water Construction on landfill Landfill
Be Waste and soil x x x x x x x x x x x x x x
De Alt.mat. in
applications x x x x x x x x x x x
Dk Residues cat. 1 x x x x x x x x x x
Dk Residues cat. 2 x x x x x x x x x
Dk Residues cat. 3 x x x x x x x x x
Fr Bottom ash x x x x x
Fr Alternative mat. x x x x x x x
Nl Granular x x x x x x x x x x x x x x
Nl Monolith x x x x x x x x x x x x x x
Nl IBC-materials x x x x x x x x x x x x x
Se In constructions x x x x x x x x x x x
Se In landfill cover x x x x x x
EU WAC Inert
landfill x x x x x x
References to Table 1: Be (VLAREBO, 2007) (VLAREA, 2003), De (ErsatzbaustoffV, 2011), Dk (BEK nr1662, 21/12/2010), EU (Hjelmar, et al., 2001), Fr (Arrêté du 18/11/11) (Chateau, et al., 2011), Nl (Verschoor, et al., 2006) (Regeling Bodemkwaliteit, 2007), Se (Naturvårdsverket, 2010)
Table 2. Elements of BWR3 of the CPR in the scenarios of constructions for the limit/guidance values of Germany, Denmark, France, Netherlands, Sweden and EU‟s inert landfill. Column headings in bold represent terms from CPR BWR3
Life cycle phases Protection of Emissions and release to
Country Identifyer Production Construction Use Demolition Disposal Workers Occupants Neighbours Environmental quality Climate Outdoor air Work environment Drinking water Soil Groundwater Marine water Surface water
Be Waste and soil x x x x
De Alt.mat. in
applications x x x x
Dk Residues cat. 1 x x x
Dk Residues cat. 2 x x x
Dk Residues cat. 3 x x x
Fr Bottom ash x x x
Fr Alternative mat. x x x
Nl Granular x x x x x x
Nl Monolith x x x x x x
Nl IBC-materials x x x x x
Se In constructions x x x x x x x x
Se In landfill cover x x x x x
EU WAC Inert
landfill x x x x
References to Table 2: Be (VITO, 2011), De (Susset & Grathwohl, 2011), Dk (BEK nr1662, 21/12/2010), EU (Hjelmar, et al., 2001), Fr (Arrêté du 18/11/11) (Chateau, et al., 2011), Nl (Verschoor, et al., 2006) (Regeling Bodemkwaliteit, 2007), Se (Naturvårdsverket, 2010).
All limit values include the effect on groundwater. Most set the limit value so that the groundwater would have drinking water quality. The exception is Germany, where acceptable addition to groundwater is the criterion. The protection of groundwater also implies protection of surface water that is fed by seepage. Some countries include surface run-off for the protection of surface water.
Protection of outdoor air is seldom considered.
The Swedish scenario for free use in constructions was partly based on contaminated site risk assessment. The scenario considered direct intake of soil, vapours, dust, dermatological uptake and home-grown vegetables in addition to groundwater (Figure 3). This is an unusually broad range of exposure pathways for construction materials.
Figure 3. Illustration of human exposure pathways of the Swedish guidelines for constructions (Naturvårdsverket, 2010).
Figure 4. Requirements for Dutch constructions with IBC materials, including covering and drainage layers (Regeling Bodemkwaliteit, 2007)
The ERA scenarios describe different local environmental conditions and compartments. However, BWR3 also outlines a life cycle perspective that requires a different methodology in order to make a comparison between release of substances from different life cycle phases, as well as consequences on different impact categories in parallel to the toxic assessment. BWR3 is not limited to toxic aspects; it also includes protection of the environmental quality where climate change is stressed.
In the context of CPR, it seems that ERA will handle the actual site related potential risks in a more proper way than LCA, while a robust LCIA model, covering the holistic risk minimisation perspective, is desirable. Such a robust LCIA model requires that impact categories for human and ecological toxicity are accepted and utilised in practice. So far, no consensus model is robust enough to be accepted in EN15804. Therefore human and ecological toxicity are not part of the mandatory LCIA methods to be included in the environmental product declarations (EDPs) for construction products.
3.3 The construction works design
The waste acceptance criteria (WAC) are an example of a scenario that considers leaching.
Precipitation on the WAC landfill percolates through the waste, through an unsaturated zone, and is transported by groundwater to a point of compliance (POC) where drinking water criteria are applied (Figure 5).
The dimensions of the application are directly related to the ratio of liquid to solid (L/S) that is used in the translation from laboratory measurement to field situation. The WAC landfill is 20 m high. This is the highest of the application scenarios, likely due to the fact that this is a landfill application while the other applications are construction works. The Danish, Dutch and Swedish applications are between 0.5 and 1.5 m high. The Dutch also have a large soil application that is 5 m high (Verschoor, et al., 2006). The French application of bottom ash is up to 6 m, and French alternative materials generally have been calculated for 0.35 to 5 m. The German roads and railroads use products in layers of 6 cm to 5 m thick (Table 3). Sweden and the WAC have a surface area, while the Netherlands and Flanders use a 1D calculation, so that the application has infinite area.
Figure 5. Cross-section showing the principle of three coupled source and transport models used for the forward impact calculation at the WAC landfill scenario (Hjelmar, 2011)
Figure 6. Model of water flow in one of the German application scenarios (Susset & Grathwohl, 2011)
Water amount is the other factor of the L/S ratio. Dutch, French, Swedish and WAC application scenarios use a net precipitation (or infiltration) of 300 mm/a for uncovered applications. The French legislation for bottom ash requires a slope of at least 1% if the application is sealed with e.g. asphalt or concrete, and at least 5% if the construction works is covered with at least 30 cm of soil (Arrêté du 18/11/11, 2011). This would reduce the amount of precipitation that infiltrated. For the Danish category 1 application, no water amount was found. Danish category 2 required covering of the material, and pavement should limit infiltration to 10% of precipitation for category 3.
The German system used 859 mm/a precipitation, with provision that areas with high precipitation (e.g. mountains) may adjust the scenarios. Infiltration into the German applications is calculated from precipitation with hydraulic modelling of the construction works (Figure 6). The German hydraulic calculations lead to high infiltration in e.g. the uncovered shoulders of an asphalt-covered road, where surface run-off infiltrates. The highest infiltration was 1803 mm/a.
POC Landfill
Source
Transport in the unsaturated zone
Transport in the saturated zone GWT
Table 3. Description of the constructions used to set limit/guidance values, or limits for use, in legislation in Germany, Denmark, France, Netherlands, Sweden and EU‟s inert landfill
Material Construction works Release
Country Identifyer Material porosity Bulk density, t/m3 Permeability, m/s Surface area, m2 Length, m Width, m Hieght, m Covering layer, m Infiltration, mm/a exponential, kappa Concentration C0 Cumulative leaching LS2 Cumulative leaching LS10
Be Waste 1.55 0.7 300 x
Dec minimum 0.27 1.4 10-6 0.03 x 313 a b
Dec maximum 0.37 1.9 10-5 ∞ 18 4 x 1803 a b
Dk Residues cat. 1 no scenario
Dk Residues cat. 2 ∞ 0.3-4 x
Dk Residues cat. 3 ∞ 0.3-1 x 10%
Fr BA in roads 1 ∞ 3-6 x
Frc Alternative mat. min 10000 150 10 0.35 x 50 x
Frc Alt. mat. max 25000 1000 150 5 300 x
Nl Granular 1.55 ∞ ∞ ∞ 0.5 300 x
Nl Monolith 1.55 1m2/m2
Nl IBC-materials 1.55 ∞ ∞ ∞ 2 x 6
Se In constructions 1.5 40000 200 200 1 300 x
Se In landfill cover 1.5 40000 200 200 1.5 300 x EU WAC Inert landfill 0.3 1.5 10-5 22500 150 150 20 300 x
a Salts
bConstant source term concentrations were applied for metals and hydrophobic
c The lowest and highest dimensions used for the scenario calculations for Germany and France are shown in the two rows
d For transport to soil and groundwater
e For transport to surface water (initial wash off)
References to Table 3: Be (VLAREA, 2003), De (Susset & Maier, 2011), Dk (BEK nr1662, 21/12/2010), Fr (Arrêté du 18/11/11, 2011), Frc (Bellenfant & Guyonnet, 2009), Nl (Verschoor, et al., 2006), Se (Naturvårdsverket, 2010), EU (Hjelmar, et al., 2001).
4 Conclusions
A typical European construction works in scenario for risk assessment of alternative materials:
A road, 10 m wide, infinitely long, or A parking area, 200 x 200 m2
Infiltration is 300 mm
Recipient for contamination is groundwater
Drinking water quality criteria are used to protect groundwater Alternative materials 1 m thick.
Range of properties found in the scenarios in this paper:
Thickness of material in application 0.03-20 m Infiltration 0.06 – 1803 mm/a
Recipients: groundwater, surface water, soil intake, home-grown vegetables, soil filter capacity, soil microfauna, dust
Materials range from all construction products through waste to specific waste streams (e.g.
MSWI-BA).
It seems desirable to have several scenarios for the intended use of construction products in environmental risk assessment and life cycle assessment. This paper has shown several examples of existing scenarios, but more work will be needed to find common ground and describe construction works with greater harmonisation.
Acknowledgements
Thank you Anke Oberender, Jérémie Domas, Margareta Wahlström, Roland Starke and Peter Nielsen for help with finding relevant legislation and background documents. Any interpretations and mistakes are our own. This work is part of Sustainable construction products and materials for renovation, and was funded by the Swedish Research Council Formas, Boliden, the Swedish Geotechnical Institute, the Swedish Transport Administration, Svenska EnergiAskor, and the Swedish National Board of Housing, Building and Planning.
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