| − | *Annual vacuuming of permeable interlocking concrete pavers can increase the operational lifespan of these pavers. <ref> Drake,J., Bradford,A., Van Seters, T., and MacMillan,G. 2016. Evaluation of Permeable Pavements in Cold Climates. accessed at https://sustainabletechnologies.ca/app/uploads/2013/02/KPP-Final-2012.pdf </ref> | + | *Annual vacuuming of permeable interlocking concrete pavers can increase the operational lifespan of this type of permeable pavement. <ref> Drake,J., Bradford,A., Van Seters, T., and MacMillan,G. 2016. Evaluation of Permeable Pavements in Cold Climates. accessed at https://sustainabletechnologies.ca/app/uploads/2013/02/KPP-Final-2012.pdf </ref> |