Tema SA Activity data (waste disposed of in landfills) before 1985 Comments CITEPA considered sewage sludge data. Absence of activity data (waste disposed of in landfills) before 1985 (although the year indicated in the &quot;Parameters&quot; sheet is 1950). Furthermore, the data between 1985 and 2004 are the same (no evolution). However, in paragraph 3.2.2 of chapter 3 of the guidelines, it is stated: &quot;FOD methods require data on solid waste disposal (amounts and composition) that are collected by default for 50 years. Countries that do not have historical statistical data to equivalent data on solid waste disposal going back 50 years or more, they will need to estimate using surrogates (extrapolation with population, economic factors, or IDEAM Domestic Wastewater Treatment Response (WWTP) may have different streams According to the different reports and supporting documentation consulted, in some cases they become biosolids that are used as fertilizers, in other cases, they are effectively disposed of in the different disposal sites, because, as mentioned above, The amounts of disposed waste reported by the SSPD do not allow increasing the level of detail to know the amount of WWTP sludge entering the disposal sites, this becomes a potential for improvement for future inventories that will be incorporated as the information allows, it is important to highlight that in the country there are approximately 473 WWTPs distributed in different municipalities that use different treatment technologies, of which it is necessary to collect specific information. Colombia, being a developing country, has presented changes that present challenges in the incorporation of information that allows estimating solid waste disposed of in years prior to the year 1985 at the departmental level (the National Census starts from the year 1985 and contains projections of population to future), since in previous years some departments were found together under the same geographical delimitation (in the period from 1951 to 1981 approximately 8 departments were created that the country currently has). When it was decided to use the biogas model, the good practices dictated by the IPCC were reviewed, and various revisions were made with the objective of finding the best indicators to estimate information prior to the year 1985; however, it was found that there was no robust information to carry out said adjustment and that taking isolated indicators without any technical solidity would impart greater uncertainty to the calculations