A number of homes in Melrose MA were flooded with sewer waste when a main line was blocked partly due to built up grease. Grease, as described in the article https://boston.cbslocal.com/2019/07/15/melrose-raw-sewage-backup-cost-investigation/ has been put down the drain overtime. When greases such as waste vegetable oil and animal fat come in contact with water and air, they oxidize and degrade. As…