Pulling up to a jobsite one morning, I saw that the concrete pump had not been set up. I jumped out of my truck and began yelling, “Why is the pump not ready to pour, concrete comes in a half hour!” My foreman told me the operator was concerned about power lines in the way of the pour. I told the operator that a pump was set up a week earlier in that location to pump the footings. He still refused to set up the pump, so we cleared a spot that took the power lines out of play. I later realized that I was wrong and that following my directions would have put the operator and the placing crew at risk.
Planning ahead is critical to safe placements
There are many factors to consider when you place concrete using a concrete pump. First, make sure you are able to provide a location that is free of debris and as level as possible. Optimally, you need to allow clear access for two ready-mix trucks to discharge at the same time. Next, consider the ground and soil conditions where you will set up the pump. If there were excavations in the area, have they been properly backfilled and compacted? Check as-built drawings to locate these areas. Use trench plates to cover questionable areas.
Power line locations also must be addressed. If boom extensions can come within 20 feet of a power line, there must be a designated spotter to warn the operator when the boom comes into the danger zone. Power line contact is the deadliest accident related to concrete pumps. Not only is the operator in danger, but so is anyone who is in contact with the concrete pump—including the placing crew and the ready-mix truck driver. Power lines near the washout area can also be hazardous.
The American Concrete Pavement Association’s (ACPA) guidelines require concrete pump outriggers to be placed not less than 1 foot away from a cut for each foot of a vertical excavation. For instance, if a vertical cut is 6 feet deep, the pump’s outriggers must be located at least 6 feet away, maintaining 45 degrees of soil from the outrigger to the toe of the cut, referred to as the one-to-one rule. Extra distance may be required if soil conditions appear muddy, soft, or loose. If the outriggers rest on shoring, ask the soil engineer what soil pressures the shoring will support and what methods are needed to spread the outrigger loads for adequate support.
Crew safety is part of the equation
Whenever a concrete pump is on a jobsite, be sure to have a person available to assist the operator when the pump truck is backing up. Identify the washout area and have a Storm Water Pollution Prevention Plan in place.
When using a concrete pump, there is always the danger of hose whipping, most often caused when air gets into placing lines. This can happen in many ways, such as when a pump stops and gravity allows concrete to free-fall from a line replacing the concrete with air, or when concrete in the hopper falls below the intake allowing air into the placing line. The air, under pressure when the pump starts pumping again, is compressed and may cause the placing hose to whip violently. When air is introduced into the placing line, the crew must stand back from the placing hose until the air clears and a steady flow of concrete is being discharged through the hose. A placing hose should never have any type of metal at its end, such as s-bends, rams horns, or even a metal connector for another placing hose. If the hose was to whip, metal devices could cause serious injury or loss of life.
The crew should have only one person giving direction to the pump operator, communicating movement of the boom, speed of placement, or the starting or stopping of concrete delivery. The ACPA recommends a set of hand signals for communication between the person giving directions and the pump operator to help ensure a safe placement. When an operator can’t see the placement, they must have contact with the placing crew via a relay person or radio contact.
When a concrete pump operator is located at the point-of-placement, away from the pump, an oiler must be at the hopper to ensure that the proper level of concrete is maintained in the hopper, to direct backing-up by ready-mix trucks, and to make sure the pump and outriggers are working properly. This person should be trained by the operator to know the locations of the emergency stops and the dangers of the pump itself; the hopper, water box, the lifting or sinking of outriggers, and any oil leaks.
Proper training leads to safety
The concrete pump operator is a highly trained person in the operation of the pump and is responsible for safety in and around the pump. They also ensure the placing crew and the ready-mix driver are observing safe practices for a successful concrete placement. Make sure your pump operator is ACPA certified. Every 2 years, ACPA-certified operators must complete a comprehensive training program in the safe operation of the concrete pump and co-worker safety as a requirement for certification.
Concrete pumping is the most efficient way to place concrete and if all safety concerns are addressed before, during, and after a placement, the chance for accidents will be minimized. If you have questions about a placement requiring a concrete pump, ask the concrete pumping contractor to visit the jobsite and help you with the pre-pour plan. They can assist in selecting the right size and type of equipment required to make the pour, and where to locate the pump in the safest location.