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HDD Culvert Cleaning Proves Effective
• A standard HDD unit capable of meeting requirements and handling a culvert cleaning project;
• Barrel reamer to loosen and remove heavy material located in the culvert;
• Push bucket designed to push material out the far end of the culvert; It can also function as a scoop to remove material one bucket at a time;
• Pull bucket for pulling material back to the entry end of the culvert; and
• Brush for fine cleaning the culvert.
Harr said the system offers many benefits. In addition to trenchless access to the culvert, speed and efficiency head the list of advantages.
For comparison, Harr cleaned two parallel 220 foot culverts, one using his system, the other with a jetter truck.
"We cleaned the first pipe with a jetter, completing the job in 6½ hours using 1,200 gallons of water," Harr says. "Next we used our HDD method, finishing in 40 minutes and used only 110 gallons of water."
Reduced water requirements is a significant advantage, says Harr.
"For example," he says, "a 60 foot culvert with a diameter of 24 inches that is 100 percent full of debris can be cleaned with our system using between 100 to 250 gallons of water. With our process, water is pumped through the HDD drill stem to the culvert cleaning tools and volume and pressure are controlled by the drill operator."
Harr says his system also provides better control of spoil than other methods.
The HDD operator controls movement of debris in the culvert. Controlled thrust and pullback allow as much or as little debris to be removed as required, allowing the spoil to be shoveled, loaded or vacuumed as it is taken from the culvert. The ability to either push or pull debris from either end also is a significant benefit unique to the Harr system.
Finally, downhole tools are built of mild steel to lessen the risk of damage to the interior of the culvert and the direction and rotation of the tool can be precisely controlled by the drill operator, who can stop immediately if a difficult blockage is encountered or when the tool passes into a void.
HDD units with pullback forces ranging from 7,000 to 100,000 pounds have been used in culvert cleaning projects, depending on job requirements.
"A smaller barrel reamer is the first tool into the culvert that checks integrity of the culvert and loosens soils for removal," says Harr. "Next, a pull or push bucket is used to remove debris. Whether it is removed from the access or exit point, often depends on requirements to preserve wetlands or stream flows."