Structure Shims can be easily installed in the following manner:

1. Remove the material (gravel, asphalt) from around the manhole.
2. Remove the cast iron frame and grate.
3. Adjust the manhole with concrete Moduloc, raising the manhole level as close to the finished grade as possible.
4. Place a 2×4 across the top of the gravel or asphalt, extending the 2×4 beyond the edges of the manhole.
5. Check the grade differential between the desired finished manhole grade and the height of the Moduloc, substracting the height of the frame and the grate from the differential. The normal differential between the Moduloc and the frame and grate is usually less than 25.4 mm (1″): it is in this gap that you place the shims. The differential will determine the thickness of shim(s) needed.
6. The Shims are placed on top of the Moduloc and shims are usually required on each of the four (4) corners of the manhole frame.
7. Fill the open gap between the frame and the Moduloc (which the installed shims provide) with concrete mortar to complete the adjustment.