excavated earth put to one side at an archaeological site, which is later used to refill the excavation. The purpose of backfilling may be to prevent erosion or vandalizing.Submitted by Veronika from Czech Republic on 06/10/2015
backfill
verb
From our crowdsourced Open Dictionary
to refill a hole with the material that has been dug out of it
After planting backfill the hole with a mixture of soill and compost.