When performing residential paving or paving on city streets, you’re guaranteed to find sewer caps, utility covers, water main shutoffs and/or manhole covers in your path. A number of companies sell manhole risers in many diameters that you can place around the obstruction to make your job of paving around them a little easier. Do that effectively by checking the subbase when you get to the site and compacting the material as soon as it’s paved.
Check the Subbase
On new road construction, the utilities are usually put in a day or so before the contractor comes in to pave. That means you have the water main or gas main shutoff sticking up in the middle of your roadway with gravel or packed dirt around it. You want to begin by strengthening that area to prevent cracking of your fine pavement in the future.
Strengthen the subbase with good soil compaction technique. Spread concrete at a depth of an inch or two in a 5- or 6-inch diameter around the structure, essentially sealing the soil and stabilizing it so it doesn’t move.
The manhole riser mentioned above goes around the cap like a sleeve and locks into place. Now you’re ready to line out your project so you work in the most efficient manner. For mill-and-fill projects especially, you want to mark very clearly where the manhole cover begins so the mill and paver operators can slow down and get over it.
Make sure you don’t drive the paver over the manhole on the first lift—the binder course. You will have the paver operator lift the screed and auger out piles of material near the manhole, but it’s an act of “equipment homicide” to drag a paver over a manhole during the placement of the binder course.
With piles of material next to the manhole structure, the laborers will jump into action. This is where the rakers and lute artists really come through for you. They will work the material into a smooth mat alongside and against the utility structure while the paver operator goes about his job down the lane.
When the lute artist is almost done working the material into a smooth and clean mat against the utility structure, it’s time to get compaction started. Don’t wait on the roller. A worker with tamp shoes and a plate compactor needs to pinch and push to material gently and firmly into place, getting initial compaction right away. It’s vital to seal the mix against the riser and compact the aggregate into place to prevent cracks and water permeability at this structure in the future.
When the roller comes through, carefully compacting near the structure, it will be able to complete densification with less effort, yet still finishing off a top quality pavement for the client.
John Ball is the proprietor of Top Quality Paving and Training, Manchester, New Hampshire. He provides personal, on-site paving consulting services around the United States and into Canada. For more information, contact him at (603) 493-1458 or firstname.lastname@example.org.