Here is another example of a New Hampshire dry well, unfortunately a bad example.

The dry well"s original cover was damaged and the pieces are inside the well. Also, this well is approximately 8-10 feet deep and as seen in the pictures the majority of it is full of debris. At some point in time an overflow pipe and trench was installed to handle excess effluent. Note the height of the staining on the inlet pipe, obviously this system has been filled to capacity more than once.
 

My recommendation was, although the system is not technically in failure, it was rated as poor and upgrade is advised.
 

Dry well full of debris

Overflow pipe

Evidence of prior flooding

Overflow trench visible at grade