Locus 15 is a 0.48m by 0.50m soil fill within a cut (Locus 21) in the plaster floor surface (Locus 4) of the OC2/Workshop structure. The layer is rectilinear but preserved curved edges, perhaps due to the state of preservation of the corners.

The soil is a medium brown clay and soil mixture which fills the entire cut and was excavated to a depth of 0.30m. Excavation ceased within the layer arbitrarily- due to the difficulty of lowering the soil further within the small dimensions of the locus. Locus 15 contains inclusions of pottery, bone, vitrified material, and small rocks. The layer contained 33 fragments of vitrified terracotta. It is not immediately clear why this cut in the floor would be filled with vitrified terracotta; the fragments are not, however, likely associated with the burning event which destroyed the building.

While Locus 15 was a medium brown soil and clay mixture, the baulk walls revealed a significantly darker layer which appears to extend under the plaster floor surface of Loci 3 and 4. It is possible that Loci 7 and 13 are equal to the dark soil beneath the floor surface but further investigation is needed to determine their relationship.