The disposal phase of green roofs has different options. Materials can be recycled, re-used, or landfilled. Water retention, drainage, and root barrier layers are manufactured out of recycled polymers, which can be recycled again when green roof lifespan ends. However, many cities do not have the required technology to undertake the recycling process. Hence, this analysis considered the worst-case scenario: green roof layers are landfilled without any treatment process. Landfill operation and maintenance costs depend on many characteristics such as: size, technology, location and remaining capacity [9,10,25]. Chang and Wang [9] estimated that the average operation maintenance cost for landfilling without energy recovery is $55.75 (in year 1992). Jamasb and Nepal [25] estimated a cost of V9.12/ton ($12.5/ton) of waste for the United Kingdom (UK). Similarly, Tsilemou and Panagiotakopoulos [54] estimated that the operation and maintenance cost varies in Europe from V3.2/ton ($4.3/ton) to V45/ton ($61.7/ton).