In the Southern Hemisphere, where the June solstice is known as the shortest day of the year, it marks the first day of astronomical winter, but the middle of winter in meteorological terms.
Backfill refers to products or materials used to fill excavations. The most common form is composed of a mixture of gypsum and calcium bentonite. Apart from filling holes, one of the primary purposes is to mantle sacrificial anodes under the ground.
In most situations, the use of backfill is not only environmentally friendly, but also very practical. The materials that make up the fill are usually excavated from a nearby location and would have to be hauled out of the area if not used.