Tips to Follow When Working with Underground Piping
Written by Tom Doty
“There are no cheap mistakes in underground.” -Tom Doty
A brief history
Underground piping has changed through the years. It has gone from wood pipe to cast iron, which was specified by an architect, to ductile iron pipe, to ACP (Asbestos Cement Lined Piping), and to C900 PVC pipe (very popular now). Additionally, it used to be that kicker blocks or thrust blocks were the norm for securing the underground systems. Now a popular choice for retaining underground systems is mega lug systems. Regardless of your tools and materials, there are many things to consider when quoting and working with underground.
Installing underground piping can greatly vary from area to area based on the geological conditions. Years ago we were working on a job and the quote had been accepted and approved. When we were digging, at about 12 inches down, we hit blue granite – a very hard substance. We had to bring in a rock breaker, just to get through it, at the cost of $130/hour (and this was many years ago). Moral of this story, know the area you are working in, don’t blow the joints, and don’t blow the budget.
Use the right type of lubricant and enough of it. For example, consider the situation when the team did not apply enough lubricant, and the rubber fish mouthed (the rubber got pinched in an area, which pushed it out of the fitting) — the water then sprayed out and ate a hole in the pipe until it finally blew out the whole joint.
Don’t forget the Thrust Blocks and/or Mega Lugs. Years back in Palm Springs, an all sand area, we were installing “dead man thrust blocks”. Dead man thrust blocks are installed about 3 ft below where the pipe is being installed. Concrete should be poured and then the rebar, or all thread rod (the dead man), should be added. Unfortunately, for the contractor, the team did not install the dead man and it eventually blew the piping out by pushing the pipe through the sand.
Undergrounds are difficult to install. There are many things to think about and consider.
Keep these things in mind when considering a quote on an underground job:
- Water district regulations. You may need extra bonds, permits, and/or certifications.
- You may need to chlorinate and bacteria test your line (typical when tying into a city main or potable line)
- You usually need to:
- Hydrostatically test the line and flush the underground system
- Backfill (which would include sand or base materials)
- Replace, fill, and compact the soil
- Repave or replace the concrete (or whatever your surface material is) and level/remove excess debris (whatever was dug up)
If you don’t work with underground on a consistent basis, it’s not very profitable. The potential problems are numerous and expensive. Furthermore, the equipment to install and deal with underground installations is also costly. One mistake could lead to a loss of all profit.
