Help finding Sprinkler Valve

[pacer]

I've been asked to help find a "lost" sprinkler valve at a local park. Apparently the park staff had purchased a cheapie Bounty Hunter a year ago and spent over 20 hours searching for the valve and couldn't find it and finally gave up looking.

The area where the sprinkler valve is suppose to be located is about 35'x200'. According to the staff, the top of the sprinkler valve is approximately 18" to 20" deep, is metal and is inside a 18"x24" plastic box which is also buried.

I used my 6" coil and spent the past couple of days searching the area and have been able to find the sprinklers, which are now buried 3" with over-grown grass. I removed a ton of trash and recovered 98 coins, a nice pocket knife and some miscellaneous junk jewelry. However, not been able at this point to find the actual valve itself.

My plan was to clean the area first utilizing my 6" coil, then go back over it with my 17" coil. Anyone have any suggestions as to what would be the most beneficial settings to utilize for this particular task?

 

[Tony]

Is it possible to sweep over another same sprinkler valve (known location) to get a reading and then go look for the original valve.

I have done the exact thing with success.

There should be little or no iron in the target (mainly brass).

Tony

 

[pacer]

Yes, absolutely, that was my attention all along. Wondering about tweaking/adjusting my settings to the target I'm searching for as I've never used my large coil.

 

[GKMan]

18/20 inches is pretty deep.. Like Tony mentioned I found a property stake for a landowner by scanning another one to get an ID on it.

 

[foggynotion]

Swing over another valve to get the target id and than discriminate out everything but that. Run manual sensitivity as high as you can and deep on. Than just sweep the entire area until you find it.

 

[pacer]

Thanks to everyone for their suggestions.

 

[pacer]

Found all the sprinkler heads and a shut-off valve for one of their drinking fountains they also couldn't find. Unfortunately, never found the valve. Come to find the valve was deeper than they originally indicated. The senior grounds keeper said it was most likely closer to 24".

 

[GKMan]

Might need one of those utility detectors that energizes the lines.