Good photo but it's hard to see the text on buildings and vaults with photo
Below Ground Enclosures
Each of our toilet systems require below ground enclosures for the solid waste (Decompose and Waste Away) or mixed waste. The TTS Decompose Vault is a prefab fiberglass containment system that is ideal for backcountry settings because it eliminates the need to transport, mix, and pour concrete.
TTS Decompose Vault
The Decompose Vault (DCV) fiberglass panels are lightweight, corrosion resistant compared to wood, and easy to transport. DCV's are available in two heights: 4ft is recommended for forested sites and 2ft for more remote areas with thinner soil. The kit comes with stainless steel hardware, cap channel with nylon rivets,, drill bits, and Pliogrrip adhesive. Assembly in the field will require user to supply drill,
See installation manual here (insert pdf link)