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Hitting Rock

Posted by drmarvell (My Page) on
Fri, Aug 8, 08 at 17:48

I've read quite a bit on here about hitting rock during construction and how it can affect not only cost, but original plans as well. I live in Tx, south of Dallas, and am fairly certain that we will encounter some rock. Is there anything you can do to discuss the possibility with the PB beforehand? How much does this add to the cost and why?

Our entire subdivision is built upon a clean-fill lot, and if the clean fill lot across the steet is any indication, there will be huge chunks of rock and concrete under the dirt. I'm a little wary now. I hadn't even considered this to be a snag in the process until reading this forum...which has been INVALUABLE to me in this pre-pre-planning stage!


Follow-Up Postings:

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RE: Hitting Rock

Well, when they were digging the hole for my pool I had a talk with the guy and hes said that if they hit rock the cost all depends on what they have to do to break or blow up the rock if needed. the cost could range from $1000 - $3000. But we had a thing in our contract that if the cost was more than we want to spend, they will just fill back and we would be out $1000, the cost to refill the hole.

also it all depends on how deep you are going if you want 8ft and they hit rock at 6, you can settle for a 6ft deep and you will be ok. Good luck my friend.


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RE: Hitting Rock

Just started my dig today and they hit rock. I have to pay
195.00 per hour. I am in WV


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RE: Hitting Rock

In Texas, there isn't an "if" you hit rock... You WILL hit rock. Given that ask for a pool build that handles all "contingencies" in the dig except for utilities rerouting. Hitting rock in Texas is not a contingency, its guaranteed. Thats why our pool here in Texas cost more than a larger pool in California. If your pool bid has all these "surprises" in it, then your pool company is not making enough money off of you and then just low balling their bid to other guys who don't normally charge for something they know they will encounter. This really doesn't allow a fair comparison of the low baller to the "realist" "experienced" pool builder more interested in "customer service" then trying to trick you into signing.


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RE: Hitting Rock

Drmarvell,

Pool builders in your area should know the land makeup of where you live. I don't recall exactly why it came up, but my PB and I actually dicussed different areas in my city. The pool builder you choose, should also know the area, what they might encounter, and bid you accordingly. Do ask those you interview if there are any contingency costs. A reliable and honest PB will be up front with you about costs you are responsible for beyond the actual pool cost.

Sometimes fill dirt in neighborhoods is not always as "clean" underneath. Those things brought in should not affect your excavation, I would not think. The rock most folks have an issue with shelfs of underground rock and indigenous boulders.

Start talking to PB's. You are under no obligation to build now. Heck, we interviewed several 2 years ago & found it was not the right time for us. Asked two of those back to bid this year and we should plaster next week. It is a big inverstment you need to be comfortable doing.

Best of luck and happy pool shopping!


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RE: Hitting Rock

I've got to disagree on the rock in TX, especially in DFW. I'm an architect and do a lot of work in the DFW, Houston and Austin areas. When we do projects we have a geotechnical report prepared. The geo does 5 borings for a site and generates a log of the borings. In the majority of DFW you don't hit rock until 15'+ down. In some areas we've done 30' borings and hit no rock at all! There are some areas north of Dallas (such as Allen) where rock is closer to the surface, but in Dallas and to the east and west of Dallas it is much further down. I've only done one project south of Dallas (DeSoto) and the rock was pretty deep there too. I really wish it was true that rock is shallow here, rock close to the surface makes commercial building foundation design and construction a LOT easier. Unfortunately we rarely encounter that in DFW.

==Our entire subdivision is built upon a clean-fill lot, and if the clean fill lot across the steet is any indication, there will be huge chunks of rock and concrete under the dirt. I'm a little wary now.==

If you're talking about chunks of rock in fill, that shouldn't add anything to excavation costs. What everyone is talking about when it comes to a pool dig is structural rock under the surface. Dirt removal can be handled with simple equipment, even a Bobcat. Rock removal is much more difficult because it has to be broken down through scraping, hammering or even explosives (that last is usually not allowed in residential areas). If any of your neighbors have pools then stop by and ask them what was encountered during the dig. You should have the same at your house, subsurface conditions don't typically vary much within a particular geographical area. You can mandate that the PB include a dig price guarantee, some will and some won't but it never hurts to ask. If one will and another won't then tell the one that won't that it's a deal killer and they may change their mind.


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RE: Hitting Rock

We live in New Braunfels hit solid bedrock at 4 feet. The dig took 9 days because of it. We negotiated a firm price prior to the dig knowing that they would hit rock and had been forwarned that costs could possibly exeed 1K per day. Other bids from PB's priced out with cost plus.
Which is another reason why we went the owner/builder(NOT for everyone, we know the crews that built our pool) route. We could see the lowball in every quote we received and when we would question it, they would either fess up or back off of the price.

Hey, they are builders here in the hill country, they know they will hit rock so why not just be up front from the beginning with potential customers.

Good luck drmarvell, hope you get your pool soon!


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RE: Hitting Rock

Hi drmarvell,
We live in Tarrant County and we had a rock clause in our contract. We had to pay up to the first $2000. We did hit rock about 51/2 feet down. It would have cost more if we did not have that clause.


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RE: Hitting Rock

We almost didnt build our pool due to rock concerns after we found out a neighbor hit rock and had to pay for 8 days of removal and still only got to 6 feet...
we hit rock at about 3 feet on our pool..solid limestone.. it took two whole days of a rock hammer at 2500 a day, they gave us a break since we payed for it in cash so all together we were out 4200, but we expected that and budgeted for it... but it was a very stressful excavation not knowing how long it would take... we were able to get to 9 feet deep and our pool is fairly large..


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RE: Hitting Rock

I live in DFW area and was also told that rock excavation would cost $250.00 an hour if the excavators hit rock. They hit rock on the first day, and rather than leave to get the right equipment, they literally scratched along the rock with the equipment they had, while charging me $250.00 an hour. The next day they showed up with the correct equipment, which kept breaking down. I was at work but luckily my Dad was visiting and documented the times they were actually digging, and the time they spent repairing the equipment. I got a bill for 12 hours!! I argued with the PB who did nothing but defend the excavators, but finally agreed to charge me for half of the time they claimed to have spent digging rock, which in my opinion was still too much. If my Dad hadn't been there, I would have been stuck with the full bill. It was very frustrating because I had no choice but to pay whatever they told me to, or they wouldn't have continued with my pool. My advise would be to insist that they stop digging if they find rock and only start the clock when they are in a position to properly drill and remove it.


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RE: Hitting Rock

Last week they started digging for my pool. It is 18x36 and I already new they would hit rock. I found a rock hammer that cost me 2k per day. After two days of rock hammering they got the hole done. Total cost to me was $5,000. 4k for the rock hammering and an extra 1k for the excavator.


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RE: Hitting Rock

I have to aggree with tresw. I built in ground pools in North Dallas , Richardson, and Plano in the late 70's. Most of those had very little rock, sometimes we hit a layer of harder yellowish substance. It broke up pretty easily though.
Now in some parts of North Dallas, and by tht I mean North of NW Hwy and south of LBJ freeway, that was my North Dallas before I moved in the early 80's, you could hit rock on one side of the street, and nothing on the other.
Back then we would rent a hoe ram and a bobcat and break up the rock with the hoe, scoop it out with the bobcat. Added about 600.00/day. But that was then.
Some builders used to advertise, NO ROCK CLAUSE. I wondered if they just charged all the pools, more for excavation.
I don't see those advertisements much anymore. If you are getting a home improvement loan, be sure to get enough for rock if they hit it. If they don't, get some really cool patio furniture :)


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RE: Hitting Rock

Great advice everyone! I'll try to get some sort of clause in the contract. If not, I will definitely add some "rock money" to the budget.

For all you experienced pool customers out there, how much do you think should be added to the budget for the "oh crap" moments? Is the same as house building...roughly 20% more than you anticipate?


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