During design development of underground vessel (mainly closed drain), two design approach is possible: Buried or NOT.
I could not find a universal design for this issue.
With buried vessel, some issue such as accumulation of toxic gas (in case of leakage) or fire issue can be resolved.
However, maintenance of buried vessel is difficult due to lack of sufficient visible access.
Also, it is not possible to use external pump for buried vessel.
External corrosion of buried vessel is another issue.
Let me know your recommendation and experiences.