The discovery of buried Roman water works (aqueducts) led to the conclusion that these water works were buried to avoid freezing by frost action.
To avoid frost effects all one needs do is enclose the water channel and being constructed from mortar and bricks etc, as in Figure 1 above, burial becomes unnecessary unless its for aesthetic reasons. The very material itself that the water pipe is made from material that mitigates frost action by providing an insulated cover.
It’s our old friend of arguing the consequent, a well developed fallacy frequently used by those who see only what they believe. That is, dogma is paramount in the ranking of empirical data, so if the data contradict the dogma, alternative explanations are sought to avoid the bloody obvious.
Here’s how the Romans solved frost action when the water works had to cross valleys or creeks,
The structures in figures 1 and 2 are parts of the Eiffel Aqueduct system supplying the Roman City of Cologne, Figure 3 below:
So why bury the water works to avoid frost damage if simply putting a lid or cap over the channel is needed?