CASE STUDY: A Million Dollar Difference


Client avoids excess project expense via experience and wide toolset.

CLIENT NEED: For years the gun club shot at targets launched over an estuary.  For decades this seemed harmless.  But the shot was lead and after many years the State wanted to figure out where all the lead was and wasn’t.  Under several feet of water was a layer of unconsolidated sediment—black mayonnaise.  Below this strata was a layer of more consolidated sediment and then under all of this, bedrock.  If the lead was scattered top to bottom or if it were found to be in both the black mayonnaise strata and the more consolidated strata, the cleanup cost would be enormous.  If it was only in the top unconsolidated strata, the cost of cleanup would be considerably less.  And, if the lead shot had fallen through and was sitting on the bedrock, no cleanup would be required.

SOLUTION: Aqua Survey was contracted to provide vibracore sampling in the area of concern.  Cores would penetrate to bedrock.  Providing an accurate look at the sediment strata, the cores would allow the client to know just how deep the lead had settled.

WHAT IF: The client had a concern.  What if the act of coring mixed the lead shot into in all strata, massively increasing the cost of dredging?

SOLUTION: Aqua Survey has many different makes and models of vibracore units.  Some are better suited for certain types of projects than others. They range from heavy duty 350 pound Rossfelders to more lightweight systems.  In order to determine which model would provide the minimal lead shot redistribution, an 8 foot high, 5 foot diameter container was filled with sediment.  As the container was being filled, lead shot painted different colors was placed at varying depths.  Different vibracore units were tested and a unit was found which provided essentially no redistribution of lead shot.  Surprisingly, it was one of our heavier systems, the 350 pound Rossfelder VT6, that proved to be the winner.  The gun club’s field project was completed to everyone’s satisfaction.

We’ve been in the sediment business long enough to not just have one or two kinds of solutions.  As they say, when all you have is a hammer, everything looks like a nail.  That’s not us.  We’re more like a well-stocked tool chest. With over four decades in business we’ve seen and overcome many unique project challenges, and, when presented with a new problem or challenge we know how to engineer the solution.  So if you are dealing with a sediment challenge and need assistance, whether it be the actual sampling or geotechnical or toxicological testing, allow us to be your expert source.