This assessment was based on a drainage stone solution compared with the use of ABG Deckdrain. In both cases the embodied carbon of the waste material is ignored. So the total carbon footprint is based on the embodied carbon of the materials, the transportation to site and emissions during construction (see ‘General Assumptions’).
The drainage stone solution is assumed to be a 150mm thick layer of single size 20-40mm stone, with a 200mm thick layer of topsoil above. There is a 300 gsm non-woven protection geotextile below the drainage stone to protect the waterproofing, and a 110 gsm non-woven filter geotextile above to prevent fine material from clogging the drainage stone. The embodied carbon of the drainage stone is assumed to be 0.0052 kgECO2e/kg (kilograms of embodied carbon dioxide equivalent per kilogram of product) as per the ICE report (Hammond and Jones, 2011) for ‘Aggregate – General (Gravel or Crushed Rock)’. The non-woven geotextiles are assumed to be 2.35 kgECO2e/kg (Raja, 2015). The embodied carbon of the topsoil is assumed to be zero due to grass growth during the lifetime of the installation. Standard assumptions (see above) have been made about the transportation of materials to site, other than the topsoil which is assumed to be site won and an indicative 1 mile of transportation is assumed to account for moving the topsoil around the site. Construction time estimates are all based on 40 hrs per hectare to place a 200mm thick layer of soil, and 25 hrs per hectare to place a layer of geotextile (Athanassopoulos & Vamos, 2011). Two machines are assumed to be required for the gravel (dozer and excavator), one for the topsoil and one for each geotextile layer.
The ABG solution is 200mm of topsoil over ABG Deckdrain 1200S/NW8. The embodied carbon of the topsoil is assumed to be site won and hence has a negligible embodied carbon, the ABG Deckdrain is 1.85 kgECO2e/kg (Heritage, 2020). Standard assumptions (see above) have been made about transporting the Deckdrain to site, and the topsoil is assumed to be site won with an indicative 1 mile of transportation assumed to account for moving the topsoil around the site. Construction time estimates are all based on 40 hrs per hectare to place a 200mm thick layer of soil, and 25 hrs per hectare to place a layer of geosynthetic (Athanassopoulos & Vamos, 2011). One machine is assumed to be required for the topsoil, and one for the Deckdrain.
Back of Wall Drainage
Carbon saving taken directly from the Costain case study (Wilson, 2018) which is a case study comparing the use of ABG Deckdrain with traditional solutions for drainage behind concrete bridge abutment retaining walls. The traditional solutions assessed were no-fines concrete and hollow concrete blocks backfilled with gravel. The carbon saving stated is based on hollow concrete blocks. The assessment in the case study discounted the removal of waste material, was based on actual distances to quarries/suppliers and material quantities as assessed by Costain.
The Carbon Footprint Standard logo shown below demonstrates that ABG’s carbon footprint assessments have been verified by Carbon Footprint Ltd. This verification covers both the company footprint in accordance with ISO 14064-3 (Fernandez, 2020a), as well the footprint of all ABG’s products (Fernandez, 2020b).
Athanassopoulos, C., & Vamos, R. (2011) Carbon footprint comparison of GCLs and Compacted Clay Liners. In Geo-Frontiers 2011. Dallas
Corney, N. et. al. (2010) Sustainable Geosystems in civil engineering applications, WRAP Geosystems Report MRF116-001
Department for Environment Food & Rural Affairs (2018). UK Government GHG Conversion Factors for Company Reporting
Fernandex, J. (2020a) Carbon Footprint Verification Report for ABG Geosynthetics Ltd, Carbon Footprint Ltd.
Fernandex, J. (2020b) Product Footprint Methodology Verification for ABG, Carbon Footprint Ltd.
Hammond, G. & Jones, C. (2011) Inventory of Carbon & Energy (ICE) Version 2.0, Sustainable Energy Research Team (SERT) Department of Mechanical Engineering, University of Bath, UK
Heritage, R. (2018) Assessed Carbon Footprint of ABG Products, ABG Geosynthetics Ltd [Accessed 4 May 2020]
Raja, J., Dixon, N., Fowmes, G., Frost, M. and Assinder, P. (2015). Obtaining reliable embodied carbon values for geosynthetics. Geosynthetics International. [http://dx.doi.org/10.1680/gein.15.00020]