grouting vs. underpinning

I have had GPR and borings done on my property and have some deep solutioning /sinkhole activity as well as significant buried organic laden sand /muck materials ( with organic contents in excess of 5%)
One engineer has recommended grouting for all sides of the house with the intent offilling the pourous and ravelled overburdened soil conditions over the limestone surface.
Two other engineers ( as well as 3 attorneys) have warned me not to do grouting because it adds so much weight to the soil and may result in damage to my home. They said I could expect to see new cracks, problems with closing doors and windows etc. One has recommended underpinning(9 pilings) to stablize the house. One has said I don't need to do anything now, but if my crack in my garage worsens, then he'd agree that I should do 8 underpins.
The underpinning makes more sense to me, but the insurance company's engineer insists grouting is the only way to do this. I'm very apprehensive about doing the grouting. Any advice?
Bill

 

[jheidt2543]

Look into "Soil Nailing" as an alternative. The "nails" are actually steel rods with screw thread tips that are turned into the soil. They provide foundation support with a bracket to the building foundation. They are much less expensive than piles or underpinning. I'm not sure how they compare with grouting, but they are much lighter. You should be able to find a source/contractor through a web search.

Good luck!

 

[reddog99o]

Grouting is probably not the best route. Weight is an issue, but if you end up gaining a lot of weight, it means you're pumping a lot of grout which means a lot of expense and a lot of porous area. If the area below is that porous, significant cost can be expected and one always has that nagging question of "I wonder if we got it all?" I recall grouting a structure underlain by "swiss-cheese" limestone and it seemed like it would never end. Underpinning is the way to go, and I really like the "soil-nailing" thought. Any ASFE Contractor should have the ticket for you. Good Luck. R.A. Hassett, P.E.
rah1616@hotmail.com

 

[rday]

I would say stay away from grouting if you can. There are a lot of unknowns involved. I had a concrete contractor tell me once he laughed every time he went out to do "mud jacking". His stance was he gets paid to pump grout into the ground and there is no way to how much you will need or if it will be successful. A win-win for the contractor as there was no warranty of any sort.

Underpining or "soil nails", which by your description sound more like helical piers would be a better option.

Rik D.
Summit County

 

[nbryan]

I have seen the helical piers utilized for repair of a crane rail foundation. The helical piers can be galvanized for protection against corrosion. The jacking is typically done by hand and can be incredibly precise, in fact on the above project, the contractor accidentally lifted the foundation too much (probably less than 1/4 inch). He was then able to jack it back down to the correct elevation.

 

[dicksewerrat]

Ask the Engr from the insurance co/ to give you his malpractice ins. carrier's name and his policy number. Once you have it, ask him if he is 100% sure of his solution.

 

[reddog99o]

Do Not Grout that Foundation. It's Money that you can't see. Underpin or Soil Nailing is the way to go.

Good Luck and Best Regards,

Rick Hassett, P.E. R.A. Hassett, P.E.
rah1616@hotmail.com

 

[PEinc]

If you use helical piers to underpin your building in a karst, sinkhole prone, area, you may find that some of the piers screw excessively deep through loose soils. It is common for piles driven in karst terrain to have erratic driving lengths - sometimes 110 or 200 feet for example. Screw pier may behave similarly. However, they may still be your cheapest option.

Grouting can be very expensive if you try to fill up sinkholes with very flowable grout. It may travel anywhere but where you need it.

I have recently been involved with a $200 million PADOT highway project in karst terrain where contractors has performed about $20 million worth of compaction grouting to remediate sinkholes near new bridge structures and under roadway paving. Compaction grouting was specified in an effort to minimize the grout take. The compaction grout is very low slump, low strength, pumped under pressure to compact the loose soils and cap over the sinkholes. Compaction grouting may be a viable option to your problem.

Contact: Layne Geotechnical

http://www.laynegeo.com

or Structural Preservation Systems

http://www.structural.com

 

[CLSecrest]

Compaction Grout is a well known Key in Florida as to help fill settling or Voids in the ground surface. I house may heave from this by building of pressure in the soils. there are a quite a few homes that were built over wet lands and were filled with trees and shrubs which will decay and create a void. Underpinnig is good if your home is settling to one side or in one Direction. you will now find geotech's suggesting underpinning and compaction grout to help reduce the settling. if you would like more information on this I would be willing to send you some information on both techiques.

Chris Secrest
Hayward Baker inc.
Tampa, Fl

 

[slugger]

I had a geotechnical investigation that confirmed sinkhole activity on my property in the Tampa area. Compaction grouting was performed as well as cosmetic repairs. Within 4 months of the grouting I started experiencing the same problems, i.e., stairstep cracks in exterior wall, cracking tile, cracking ceiling, cracking pool deck coming up in chunks, brick facing separating from block walls. I am also completely surrounded by confirmed sinkhole properties. Geotechnical firm recommended grouting only and we went along with this plan. Then when I had another sinkhole start forming approx. 5 feet from the original sinkhole, they only came out and did a hand-auger test, said it was from organics, and my insurance company cancelled my policy saying we were in a hurricane-prone area. No guarantee with the grouting! You will continue to have problems. All of my neighbors' geotechs advised underpinning, minipiles or underpinning and grouting.

 

[Focht3]

dicksewerrat:
I love your post!

FloridaBill:
As you can see from all the comments, grouting is considered to be a bad idea - by almost everyone but the insurance companys' engineers, that is. If you want to put the insurance company on the spot, do what dicksewerrat suggested, with a twist. Demand that their engineer provide a sealed repair plan and proof of professional liability insurance with a per occurence limit of not less than $1,000,000 and an aggregate cap of not less than $2,000,000. From an A- (or better) rated insurance company. (Financial stability, you know.) And watch that insurance company crawfish! They will argue that their engineer is only responsible for providing them with a "reasonable" fix so they can estimate the cost and pay you. I'd reply by telling them that a repair plan with no "guarantee" is a repair that isn't worth buying!

 

[TJWATKINSPG]

Focht3
I am thrilled that you responded in that way. "...a repair plan without a guarantee is a repair that isn't worth buying.." While I try to view my clients projects as if they were for me, I do often put in those weasel words. I guess that comes from being from Texas where standing with your feet planted on both sides of the fence will get barbed wire cut where it counts. Good call.

The truth will set you free. Best of luck. Geodude

 

[FCastellano]

What exactly is meant by a "sealed" repair plan?
Thank you in advance...

 

[PEinc]

A sealed repair plan is a "blueprint" showing the required repair work. Sealed means that it was prepared by a licensed engineer who has afixed his or her professional engineer's seal or stamp to the plan. Clear now?

 

[reddog99o]

Do not grout that situation. Lawyers aren't engineers!!!!If you chose to grout, you could be pouring concrete into the ground and never know where it goes. I reiterate my past comments.

Best of Luck,

Rick Hassett

R.A. Hassett, P.E.
rah1616@hotmail.com

 

[DBNodurf]

Well, regarding soil nailing, may I presume the nails are vertical? The assumption with soil nails is that they are "pinching" the soil together, thereby increasing its effective friction angle, etc, etc. This is terrific if the soil will always be there... but in the case of karst terraine, the soil may ravel out from the nailed area, thereby rendering the soil nails useless. I concur with the rest of the discussion wrt grouting versus everything else and am thinking minipiles or micropiles...

Please feel free to disagree as vigorously as you wish, as long as I can learn something too!

D. Bruce Nothdurft, MSCE, PE, PG