First contact your building department to find out how much concrete is required around the lally column (bollard)—normally a hole a minimum 6 inches larger than the pipe on all sides is required. Once you know that dimension, you can rent a demolition/breaker hammer or rotary hammer. Make sure it comes with both a chisel and a breaker point.

Use the breaker point to begin punching a hole in the concrete. Make the hole as wide as required for the new concrete, and use a post-hole digger to remove the soil.

If you use a rotary hammer to punch the hole, start by making a series of smaller holes in the surface because the rotary hammer is lighter. Use a 5- or 10-pound maul (sledgehammer with a short handle) to break the concrete around these holes. Alternate the rotary hammer and maul until you break through the concrete.

When you reach the soil, start undermining—removing the soil from under the concrete using a small garden spade. You'll find the concrete will break much easier—whether you are using the rotary hammer or the maul—when it's hollow under the concrete. It's a slower process but very effective. Alternatively, you can get down to business and use a demolition/breaker hammer.

Set the bollard post into the hole, and use a level to make sure it is vertical. Put concrete into the hole around the post and flush the new concrete to the existing floor concrete. As you work, check that the post remains vertical.

Remember to fill the steel column (bollard) with concrete as well.

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C.R.S., Inc. · Spokane, Washington · USA