Dredging Myths

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Willard Says……

Myth. Half-true or fictitious information.

The sand and gravel dredging industry is overloaded with myths. See if you can sort the oats from the horse pucky in this list of outright fiction and partial truths.

  • Installing a suction jet assist will increase pumping distance.
  • Converting a hullpump to a ladderpump will double production.
  • Rotary cutters work as well as those expensive, high-maintenance chain diggers.
  • You cannot put too much horsepower on a dredge pump.
  • Run the dredge pump at top speed to get top production.
  • A velocity meter is not worth its cost.
  • Experienced operators are good operators.
  • A ladderpump cannot cavitate.
  • Dredges with round pontoons are likely to roll over.
  • Diesel horsepower is weaker than electric motor horsepower.
  • Installing a suction jet assist will ALWAYS increase production.
  • All suction relief valve systems are the same.
  • Replace steel pipe with the same-size plastic (HDPE) pipe.
  • Frequent parting of discharge pipeline joints is normal.
  • A rotary cutter can produce effectively where there is a lot of oversize.
  • Dredge operators work best when unsupervised.
  • Suction relief valves let water into the suction pipe so they are worthless.
  • Managers are most effective when they stay in their office.
  • Running out of fuel is normal and provides relief from the tedium of dredging.
  • Instruments are for amateurs; “experienced” operators do not need them.
  • Round pontoons do not “float” a dredge as well as square ones.
  • The best operators always maintain a certain vacuum regardless of conditions.
  • Pump manufacturers know all there is to know about their products.
  • Recommendations from a “dredge expert” should always be accepted without question.
  • Plastic (HDPE) pipe “pumps easier” than steel pipe.
  • All makes of dredge pumps of a given size perform the same.
  • “This dredge can pump 60 percent solids.”
  • Operators, left alone, can be trusted to do their absolute best at all times.
  • Anyone can be a manager.
  • Professional engineers make the most effective managers.
  • A pump curve accurately projects pump performance.
  • Operators work best in a cramped, cold/hot, noisy, filthy environment.
  • Discharge pipe size is not important.
  • “Reconditioned” dredges are as good as new dredges.
  • Once a round pontoon is loaded to over half of its diameter it will sink.
  • A velocity meter is not required if the operator can see the discharge plume.
  • A suction jet assist must be located as close to the suction inlet as possible.
  • A ladderpump must be located as close to the suction inlet as possible.
  • A ladderpump is required for digging depths greater than 40 feet.
  • Having a dredge sink is “no big deal” for a dredge owner.

Comment, question, criticism, information on products mentioned? Contact willard@willardsays.com.