Hitting Rock (Excavation)

sheree202

Gold Supporter
Jan 15, 2016
245
Lawrenceville, GA
Has anyone hit rock during excavation and if so how costly was it? Our neighborhood has big rocks underground...they stack them along the streets when building new homes. The excavator mentioned to me that he knows my area has rock and it can get expensive quick if they hit it. :(
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
The topic comes up from time to time, when it is hit the big question becomes is it small enough to remove, and is not can you redesign the pool to go around it.
 

ellsian

Well-known member
Jun 26, 2014
216
Peoria, AZ
This is relatively common in Arizona depending on how close you are to the mountains. We don't so much have boulders of rock, just more like rock layers known as Caliche. It's called a "hard dig" over here, and I was told it can range from $1500 - 5000 extra :( Not sure how much something like that would be in GA.
 

JamieP

Platinum Supporter
We knew to expect rock (limestone) right under the surface when we dug our pool. What we didn't know is if we'd hit the "blue rock" under the limestone that is even harder to get through. The excavators around here charge a base price for the pool depending on its size, then an hourly rate (typically $250/hour) once they need to start using the rock hammer. The guy I went with instead charged by the volume of rock he had to haul off, which was a more definite amount based on the pool size instead of an open ended amount of time, and I liked that. He was actually the excavator I felt was the most experienced and the one I had most confidence in, so that helped too. In the end, though, if I were to have calculated the hours vs the price for what he had to haul off, it worked out pretty comparable, since we did end up hitting the blue rock and it was very very hard and took a long time to get through.

The cost of excavation was pretty steep for us because of the rock, but there was no getting around it, and we factored it into our budget. The hard part is the not knowing so not being able to budget well, but we knew what to expect and had a worse case scenario factored into our budget.

One thing I also had to consider was what to do with the rock. Since we were O/B and my excavator wasn't local to my area, he wasn't familiar with where to dump it. Supposedly it's easy to find people who want good fill dirt, but not everyone wants your rock! If you have a PB then they will figure that out for you, but I had at least one excavator that didn't want to deal with me because it was too much trouble figuring out what to do with the rock. My excavator said he'd call around, but I decided to be proactive and tracked down my own place to dump sooner than he probably would have gotten to it. It all worked out in the end, fortunately.

Good luck! I hope for your sake all the rocks in your area decided to take up residence in your neighbors' yards instead of yours! ;-)
 

sheree202

Gold Supporter
Jan 15, 2016
245
Lawrenceville, GA
Okay, thanks for all of the information!! I emailed the excavator and asked him specifically how does he charge if he does hit rock. Hoping to get lucky and have all of the rock in my neighbors yard too haha! :)
 

And5555

Well-known member
Sep 19, 2015
144
Austin, TX
Good idea. I think different places handle it differently. Jamie's charged by the hour but mine was fixed cost. In Austin, all excavators just assume rock and always come with a jackhammer attachment for the backhoe. They all also charge fixed prices (though you can do it differently with a rock clause - don't think I would want to bet against them as their pricing takes into account their guess). There's a video of them using it somewhere in my build thread. They were jackhammerring for a solid day, but the dig still only took 3 days even with the cost of going 150 feet each way to and from the street (extra cost).
 

skylar18

LifeTime Supporter
Apr 8, 2013
299
Austin, Texas
I had a fixed bid in Austin as well. I got lucky, they estimated dig would take 2-3 days. Took 2 1/2 weeks. They were quite upset they underestimated the dig by so much. The only thing that saved my PB was the excavators were in house so it kinda was a fixed cost already. I definitely didn't need gunite I had so much rock!
 

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
4,652
Sydney, NSW, Australia
For us, it was "$poolprice" plus AU$155 per cubic metre (~US$160 per cubic yard) including disposal. In Sydney, disposal is dear because everything gets sorted/tested for contaminants due to some dodgy practices in the past. Gone are the days of free fill!

For budgeting, I assumed the whole thing was rock so whatever the number, we were "to the good." As it turned out, it averaged ~1/3 clay on top, and almost 2/3 rock so we had a few thousand to spare. The up-charge was AU$5100 for 33 cubic metres. The PB was willing to quote all-in, but said that's how he would adjust the price - all rock. The worst outcome here in Sydney is if the pool sits on rock for part of its footprint, because then the rest must be piered to rock.

The good thing is that the pool is locked into bedrock, no piers were needed, and it ain't going anywhere!
 

doobs41378

Well-known member
Mar 8, 2013
350
New Hampshire
View attachment 46052

They hit rocks where we are. This is literally the top coat and the first 5 minutes of digging to produce this small pile. Apparently the people building our house just put all the rocks they found in the back yard and buried them. It cost us about $5000 extra due to the trucking them out. Some times only 2 rocks per dump truck load. It was not much fun. Good luck!
 

sheree202

Gold Supporter
Jan 15, 2016
245
Lawrenceville, GA
View attachment 46052

They hit rocks where we are. This is literally the top coat and the first 5 minutes of digging to produce this small pile. Apparently the people building our house just put all the rocks they found in the back yard and buried them. It cost us about $5000 extra due to the trucking them out. Some times only 2 rocks per dump truck load. It was not much fun. Good luck!
What a nightmare!
 

Nectarologist

Well-known member
Apr 3, 2015
518
New York
Good idea to find out pricing before hand. I hope it works out well for you sheree.

You can also have instances where a developer buries tree stumps in a development. If you're building a pool where they happened to dump it's not good either.
 

ellsian

Well-known member
Jun 26, 2014
216
Peoria, AZ
Good idea to find out pricing before hand. I hope it works out well for you sheree.

You can also have instances where a developer buries tree stumps in a development. If you're building a pool where they happened to dump it's not good either.
This happened to my parent's pool in the 80's. They started digging up the ground and found a dump for all of the trees that the developer had buried instead. They ended up having to remove some of the trees and change the shape of the pool to fit. I don't think legally the newer builders are allowed to bury that stuff anymore because it can cause threats to the foundations of the homes.