Amphibians require a humid environment, so hibernacula for them are best located close to water. A well-drained rockery near to a pond would be ideal.
To build a hibernaculum for amphibians, mix plenty of coarse rubble with leaf mould and rough pieces of wood. If you are building a new pond, you can make a hibernaculum with the soil that you removed to create the pond.
Line the bottom of the hole with brick rubble, and then fill with soil (excavated from the pond, if you are building one), leaf litter, loose rubble and wood. Cap it off with brick rubble interspersed with large pieces of concrete to create gaps that will allow amphibians into the mound.
Cover this rubble cap with a thin layer of soil and woody brash, taking care not to block off any gaps.