32 CFR § 553.14 - Eligibility for interment of cremated remains in the Arlington National Cemetery Unmarked Area.
(b) Cremated remains must be interred in a biodegradable container or placed directly into the ground without a container. Cremated remains are not authorized to be scattered at this site or at any location within Arlington National Cemetery.
(d) Consistent with the one-gravesite-per-family policy, once a person is interred in the Unmarked Area, any derivatively eligible persons and spouses must be interred in this manner. This includes spouses who are also primarily eligible persons. No additional gravesite, niche, or memorial marker in a memorial area will be authorized.