# Screwdriver Test



## dfw_pilot

In case anyone doubts the veracity of the screwdriver test: It works. Have a troubled spot? Before pouring on more costly water and fertilizer, pull out your trusty screwdriver. Push it 6-8 inches into the ground and see if you find anything under the grass, like construction debris or rocks. That can be a simple cause for troubled spots in your lawn.

I hope this is the end of my troubles in this spot!


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## GrassDaddy

So I decided to try this and video it. I literally had no idea there would be a rock this big. Such a simple thing I tell everyone to do it now!

https://youtu.be/5Nub-KedN1w


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## dfw_pilot

Like the Captain of the Titanic, I too was surprised at how big this was below the viewable surface. The highlighted white areas are what poked up above the dirt.


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## wardconnor

So rewarding


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## Alan

Holy crap!!! Too bad it wasn't a chunk of gold.


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## GrassDaddy

Haha its insane


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## Redtenchu

:shock: :shocked: :shock:


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## Mightyquinn

Holy crap Batman!!! That is a HUGE piece of concrete!


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## J_nick

MQ have you been doing that to people's yards?


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## Mightyquinn

J_nick said:


> MQ's have you been doing that to people's yards?


I have done something like that but it's usually during construction so it's up to the builders to remove anything the concrete truck has "washed down" after pouring. That is just poor site cleanup after the house has been built.


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## kolbasz

Concrete and gravel and tree roots...

Concrete tree lawn https://imgur.com/a/vvb33
https://imgur.com/a/WuDqF


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## g-man

Reviving an old thread. This is an example on when the screwdriver test did not work. This trouble area always dried up on me sooner than the rest. The screwdriver test passed, but I knew something was wrong. After a rain with a 12in spade shovel I found the problem.





The builder left these shards of concrete/rock in the corner of the driveway. The landscape crew covered it with 8in of fill dirt. It was ~6in deep. I filled 5-6 of these buckets. I back filled with top soil and tried to compact it the best I could. I had to stop because the 92F heat got to me and I ran out of top soil. I need to continue this work. It was cool to see all the roots within the rocks (I missed taking a picture).


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## Colonel K0rn

g-man said:


> Reviving an old thread. This is an example on when the screwdriver test did not work. This trouble area always dried up on me sooner than the rest. The screwdriver test passed, but I knew something was wrong. After a rain with a 12in spade shovel I found the problem.
> 
> 
> 
> 
> 
> The builder left these shards of concrete/rock in the corner of the driveway. The landscape crew covered it with 8in of fill dirt. It was ~6in deep. I filled 5-6 of these buckets. I back filled with top soil and tried to compact it the best I could. I had to stop because the 92F heat got to me and I ran out of top soil. I need to continue this work. It was cool to see all the roots within the rocks (I missed taking a picture).


Wow, that's impressive that something only 6" deep would cause so many troubles for lawn fans on the surface. Nice detective work! How'd you get them so clean? Looks like you have the beginnings of your own chi garden.


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## g-man

I scouped them out. The clay did not move thru it. It was just a layer of that stuff. I'm trying to figure out how to get rid of them. Maybe it will go with the trash one bucket per week since it is heavy.


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## Ridgerunner

This thread is painful. When 50% of your lawn has dead areas due to subsurface stones and construction trash, you are no longer growing grass. You are raising rocks. I didn't use the screwdriver test until last Fall. I was in a state of denial. I bought an aerator instead. Maybe I'll post some picks one of these days. But for now...it's too soon. /wry smile


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## gatormac2112

How deep does the soil need to be to have healthy growth? I'm pushing down around 6-8" in weak spots in my yard with no obstructions.

EDIT: Going around the entire yard reveals that weak spots have something hard underneath, about 2 to 4" beneath the surface. I'm going to have to dig up probably 10% of the surface area of the lawn by guesstimate. Since the plan was to level next spring I suppose I should use that opportunity to dig up the rocks, fill it in with sand/topsoil, then hope the grass will spread over those areas over the summer?

At least I know what needs to be done to the backyard before allowing sod to be laid down.


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## Powhatan

Humm, I wonder what this 2FT exposed piece of wood laying flush with the ground is? It's preventing lawn growth to fill in this spot. Could it be a cut tree root when the home builder cleared the lot? Let's dig it up and find out, won't take too long -  


30 minutes later ... Nope, doesn't look a tree root.


Another 30 minutes later ... It's a 25FT felled tree trunk that got hastily shallow buried when the house was built.


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## Greenrebellion

@Powhatan Wow, that's crazy!


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## dfw_pilot

Lord have mercy.


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## g-man

Started doing the trench for my last irrigation zone. I strated in the corner thinking it will be easy. I was so wrong.

First I discovered a concrete rock.





But then I found a larger one. I started to break it up with a chisel, but I was not getting it out. So I grabbed the pick axe.





It was a large chunk of leftover concrete buried in there. This corner always struggled, but being a corner I assumed it was normal to dry out.

That consumed most of the afternoon, so now I am behind schedule.


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## ken-n-nancy

g-man said:


> ... I discovered a concrete rock. ...


Great to get that out of there! Bet'cha the grass doesn't dry out as fast there next year! Good job!


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## Suburban Jungle Life

:shock:


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## LawnNeighborSam

I have this small area that failed the screwdriver test. I kind of been putting it off because I know once I dig it up I'm gonna find a mothership of a concrete boulder under it


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## g-man

I continued working on the install of sprinkler in the front of the house. I was digging the hole for the spray body and found a piece of tarp. I started to pull it out.


Well it was too big. I ended up pulling squares of grass out. There was a lot of sand in there.


This is what was in there. It is a construction material to prevent erosion and it is filled with rock. I also found particle board, and a 5 gallon bucket of rocks.


Amazing that the grass is was doing great in this area at 1in HOC.


Edit: added the pictures. I'm afraid I will find a body next time I dig.


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## Delmarva Keith

g-man said:


> I continued working on the install of sprinkler in the front of the house. I was digging the hole for the spray body and found a piece of tarp. I started to pull it out.
> 
> Well it was too big. I ended up pulling squares of grass out. There was a lot of sand in there.
> 
> This is what was in there. It is a construction material to prevent erosion and it is filled with rock. I also found particle board, and a 5 gallon bucket of rocks. Amazing that the grass is was doing great in this area at 1in HOC.


If you kept digging you would have found the treasure chest. They dumped all that garbage in there to hide it


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## dfw_pilot

I was pretty sure I'd found the second Shroud of Turin, but alas, it wasn't.

This area always struggled. Passed the screw driver test. I finally said screw it, I'm digging.


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## DR_GREENTHUMB

I have two trouble spots, test proved an abundance of rocks. Knowing this, is there a proper way to save your grass? I assume you make a square or cut of some sort, but is there a better time other than now? I would assume to do this before the grass starts to green in the spring? Or over the winter months? I am just hesitant to start cutting and digging now?


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## g-man

For cool season, I like to do this in the fall when it is actively growing. I don't know about Bermuda.


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## DR_GREENTHUMB

That is kind of what I thought, I may wait until next Spring unless someone talks me out of it.


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## Slingblade_847

Just some humor. I had a small brown spot in my lawn, gave it the screwdriver test and got all of about 4 inches until I heard metal on rock. A few hours later, a total of about 300lbs of concrete was removed. Reminder to check brown spots for issues.

Glad I'm planning on a renovation this year and found this!!


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## glnh32

wow - I'm impressed that the concrete was freely moving and was "easy" to get out! Nice work.


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## Slingblade_847

Hahaha!!! Swinging the pick axe was easy, doing it for 2 hours is what took some effort. Lol!!


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## Gilley11

Wow, that's crazy. So many stories of buried goodies in people's yards.


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## FuzzeWuzze

Looks like your property is where they stopped for the day when they were laying the sidewalks.


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## g-man

@Slingblade_847 I copied your post and added it to this thread. It is amazing what could be underneath our yards.


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## rjjrmiller

Ive addicted to following up the screwdriver testwith my cordless drill with a twist type bit about 8 inches long and half inch wide.

The deep twisting grooves constantly remove soil materials acting like an auger pulling out soil and mini aerating the area if I drill multiple holes. The screwdriver makes a hole but doesn't remove soil. 
If I see sawdust coming out then I know I got another root.

I'll often get lawn care addicted and drill the spot with 50 or more half inch holes. (Mini aeration) These smaller holes are only noticable if you are up close and know where to look.

Yhe reward it seeing the new amazing drainage it creates during a good watering.

Screwdriver test first because broken bits in the soil only add to the problem.

. I must look like a crazy man, but to see my half inch holes draining water so easily is worth it. Hopefully it still works next year too.


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## uts

Had a small 18" diameter spot that was not growing stuff. Screw driver was done with a pro plugger. I just started digging after not being able to go 2 inches.


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## TulsaFan

I wouldn't even consider doing a Screwdriver Test unless you own a pick mattock. Digging without one is insane.

I just created two more flowerbeds along the south side of my house and the amount of mortar, bricks, and concrete left by the masons was mind boggling. I feel fortunate to know well enough to have the Mattock in my digging arsenal.


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## StevenA

How deep do small/medium rocks have to be to disrupt grass? I some small (1"-2" diameter) rocks about 5-6 inches down then some larger feeling rocks ~8" down in some areas. The smaller ones can be a pain to find since the screwdriver will frequently miss them. I'm using an 8" screwdriver.

When I do find this stuff, whats the best way to dig them up without ruining that section of grass? Last time it was just a small hole and I watered it in a ton after. Looking better after about a week.


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## kay7711226

Please, No more Screwdriver test for me!







Recovering after heart surgery, KBG filling in after transplanting from my side box.


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## Slingblade_847

@kay7711226 - HOLY SMOKES!!

Hope this rock wasn't the cause of heart surgery but could understand if it was...

Good work and thinking on the use of 2x4. Simple....NOT easy.

People would pay good money for a rock like that. Guessing if someone told you what you were in for, you'd of paid good money to have it removed!

...job well done.


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## Green

TulsaFan said:


> I wouldn't even consider doing a Screwdriver Test unless you own a pick mattock. Digging without one is insane.
> 
> I just created two more flowerbeds along the south side of my house and the amount of mortar, bricks, and concrete left by the masons was mind boggling. I feel fortunate to know well enough to have the Mattock in my digging arsenal.


That's a good idea.


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## kay7711226

Slingblade_847 said:


> @kay7711226 - HOLY SMOKES!!
> 
> Hope this rock wasn't the cause of heart surgery but could understand if it was...
> 
> Good work and thinking on the use of 2x4. Simple....NOT easy.
> 
> People would pay good money for a rock like that. Guessing if someone told you what you were in for, you'd of paid good money to have it removed!
> 
> ...job well done.


@Slingblade_847 THANK YOU! Even though I will not wish this on my worst lawn enemy :lol: :lol: :lol:


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## JDay

Here's a good one from my front yard. Been here almost three years and just decided to check it out today.


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## cavince79

JDay said:


> Here's a good one from my front yard. Been here almost three years and just decided to check it out today.


That's one of the best ones yet. At least you don't have to dig that one up.


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## JDay

I shouldn't have started with this. Now I've found what appears to be a 3'x3' rock smack in the middle of my front yard and another metal valve box not too far away.

My neighborhood was developed by a company known for cutting corners, so who knows what all I'm gonna find now that I've opened this can of worms.


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## JDay

cavince79 said:


> JDay said:
> 
> 
> 
> Here's a good one from my front yard. Been here almost three years and just decided to check it out today.
> 
> 
> 
> 
> 
> 
> 
> That's one of the best ones yet. At least you don't have to dig that one up.
Click to expand...

I might... My driveway is just a few feet away in line with the edge of the picture. The valve box isn't square to the driveway, so my OCD self may have to adjust it.


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## NeVs

JDay said:


> cavince79 said:
> 
> 
> 
> 
> 
> JDay said:
> 
> 
> 
> Here's a good one from my front yard. Been here almost three years and just decided to check it out today.
> 
> 
> 
> 
> 
> 
> 
> That's one of the best ones yet. At least you don't have to dig that one up.
> 
> Click to expand...
> 
> I might... My driveway is just a few feet away in line with the edge of the picture. The valve box isn't square to the driveway, so my OCD self may have to adjust it.
Click to expand...

Dang! I'd be digging already! 🤣


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## Lawn Whisperer

Decided to do a screwdriver test before mowing. This area struggled throughout the summer, but didn't want to dig it out until the right before overseeding.

I found all these rocks from digging one hole. It's likely that there are more of these around the driveway and all over the yard from a new constrction.


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