I changed the answer from 26 to 4065.333. Page 138. On a table titled "Evironmental management and fighting climate change", on the row "Waste generated [GRI 306-3]".  

Calculations: the information on the source was on tonnes and I was asked to give the answer in cubic meters, so I took 1.5 tonnes = 1m^3 and calculated the answer. 6098/1.5=4065.333

the source tells us there where three spills, of 1, 5 and 20 m3. If we sum these up it gives us 26