Installation in Grass, Dirt or Gravel (All PenCell Units) 1. Prepare the excavation approximately 6” deeper than the overall height of the enclosure. The length and width of the excavation should be determined by adding 4” to 6” to the overall length and width of the handhole or pull box. 2. Place approximately 3-6” of compacted material such as sand or gravel in the bottom of hole. Gravel is the recommended material because of its drainage characteristics. The compacted material should be leveled so the top of the handhole or pull box is flush to the grade. 3. Place selected backfill into the excavation at 1’ lift and compact either by manual compacting or flooding the excavation to achieve the desired relative compaction. Install with cover in place.