Detector needed for upto 3 feet deep find concrete steel reinforced lids please help

[JoshiD]

I have taken on a contract to survey a heap of sites for "Australias National Fibre Runout (NBN)" and it has now come to the point where I need to locate pits which have been covered over in garden beds/under paving

The pit lids are made of concrete with a steel reinforcement grid inside and range from a shoe box size upwards with a depth no more than 3 feet deep

At this stage pit locating is not covered under out scope of works so for now I need to pickup a 'starter' detector that gets the job done with the want that once we have convinced them it is worth doing and negotiate to actually be paid to find them, so can you please suggest a cheaper unit and also something that would be rugged and quality to buy for all crew requiring it.

Any help would be greatly appretiated as I am new to the metal detector arena and need to make this happen as fast and painless as possible.

Thanks in advance

 

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[Gold Maven]

Welcome JoshiD,

This doesn't sound easy. Most precast concrete boxes that small would only have wire mesh reinforcement, if any steel, which is not a very big target to locate at 3' depth. Even rebar, 3/8" for small precast lids/boxes is a small target at 3' for a regular detector.

There are "two box" units for greater depth, but I'm not sure if they would be sensitive enough to locate some reinforcement wire at 3'.

Good Luck.

 

[boogeyman]

A two box would be the best bet. Might take a little while to get used to it. Another alternative you might look at is a machine with a big coil. A Sovereign with an 18" coil might work. Mine will "see" tin can lids at that depth. Give Minelab customer service a call. They are really good at helping!

 

[Pointman]

Welcome JoshiD,

This doesn't sound easy. Most precast concrete boxes that small would only have wire mesh reinforcement, if any steel, which is not a very big target to locate at 3' depth. Even rebar, 3/8" for small precast lids/boxes is a small target at 3' for a regular detector.

There are "two box" units for greater depth, but I'm not sure if they would be sensitive enough to locate some reinforcement wire at 3'.

Good Luck.

I agree. A mid priced detector may not have problems finding something this large, but 3' is really pushing the depth. I think that anything smaller then man-hole size is really pushing a detector to find at 36". Shoebox size at 2 feet probably wouldn't be a problem. A detector with a very large coil may find it.

 

[Bombguy]

EM61 WILL FIND IT NO PROBLEM..I use this at work..its portable GPR.