The following instructions detail how to modify a typical plastic pit (Types 1-8 & 53) to increase the pit height with a riser. 2 pits are required.

1. Cut one pit below the step at the cutting line. Use an angle grinder with a cutting disc or cut with a hand saw. The top section will be used as the riser, discard the bottom section.
2. Smooth cut edges with a rough file.
3. Place the riser into the rebate area of the second pit.