What I know of this is shallow at best and today a contractor today shattered that. My understanding was that you put in grapefruit size rock 8 inches deep as the bottom layer. Then golf ball size stuff for 4 inches. Finally 3/4 DG which is a mix of 3/4 inch crushed rock mixed with other grades down to sand and that is what packs in like concrete. NO ROUND RIVER ROCK....EVER.
This contractor wants to lay in 10 or 12 inches of 3/4 DG and roll it. He says that when the dump truck backs onto the dirt he can tell if the truck sinks if the underlying soil will support a bus with only 3/4 DG. seems if to me but I have gone into so much overkill in my life I often check myself.
I think that the soil under the area is water soaked sand. How can I get that tested....soil engineer? What should that cost? Do they charge by the test or hole or foot stomp....what?
I know that many have remarked about doing this in the past. The failures sure interest me, as well.
John
Your right on the river rock, might as well put in marbles.
I did the hit and miss compaction test. I put in about 8" of #1 crushed stone. After a year or two if it would have sunk I would have added some more. After the first year there was a depression where the rear wheels sat, a few minutes with a rake and shovel fixed that.
JIm
Your wasting a bunch of money John 8 inches of base materiel with a geo/mat underneath will last for ever in a wet area the mat will cost you about a buck a square yard
good luck
Where I live we normally dig out all the top soil, how deep it is can very, but just arbitrarily going 8" will not cut it if you still have top soil, it must all be removed. Unless there is a very deep hole we usually just fill back in with what they call Sure Pack. It is a crushed stone product, I am not sure what type of stone it is, but it's kind of a greenish blue color. It packs good and hard, but can be raked and leveled out with a tractor.
I park my bus in my back/side yard with the front of the bus just off the concrete driveway the rear wheels come right to the edge of the concrete.
I had ruts about 4-6 inches deep where the front wheels plowed through the ground.
After filling in the ruts I put about 6-8 inches of the 3/4-crushed driveway limestone in and packed it down with my truck. Nice and solid for two years now, this last spring we had record rain and flooding in the area and this stuff stayed solid.
Of course my yard is basically clay.
You can put your larger stones in and fill over them with stabilized sand. Last you can put you 3/4 stones and roll that out. Stabilized sand will lock up as it has a concrete powder mixed in it. Stablized sand is a code requirement for large underground water pipes. They put the sand in and pack it down. The pipe is placed on top of that and back fill around it. The pipe is essentially sitting on a concrete pad that will last a long long time.
I put in river rock and it seems to be working fine. I didn't know better at the time. My bus does not sink in as I have a sand/clay mixture in my yard.
I had only yesterday heard the name "GeoMat" and had its function described. That is a must...at least here it is. I was waiting for anyone to tell me I didn't need it as it is a large expense but apparently I do need it so that $50(?) is committed.
I failed to share an interesting anecdote with you all and it has great bearing on my project. A few years ago I installed a Heat Pump system to replace all the wall heaters in this 1921 "house wreck". I had to upgrade the electrical at that time and in doing so I had to install new ground rods that are 12 feet long. Two were called for and they were 20 feet apart along the foundation. This place has a short foundation and a crawl space. I bought the spendy copper clad rods and a metal-post driver and a 20 pound sledge for the short work. I figured that the folk that poured that foundation would have dug out a little under it and maybe there was some looser earth under there. After all, some of it might still be uncompacted since it was only put in like.... 91 years ago. :P I set the point of the rod in the dirt about 12 inches from the foundation and angled the rod to go under the foundation. 20 degree tilt of the rod and I did that for a second and more important reason.....The eves are only 8 feet above grade and the rod wouldn't fit unless I put them in 3.5 feet from the house in the true vertical. You may have lost confidence that this tale can ever "connect" with a parking pad topic but bear with me. Having set the rod at the angle I leaned on it with all the muscle that 270 pounds conjures and you will never guess the result.....the rod went into the earth 2 feet like it was sliding into Crysco. Dumbfounded I I put mu back and mostly belly into another "push" and got another six inches. All tolled I pushed the rod into the earth 4 plus feet before I applied the driver. I was getting six inches travel with every strike at the outset till the last 2 feet. That felt like compacted river rocks about softball size. The driver operator earned his keep that day just to get me the last couple feet. What a guy. Cost me a 12 pack of Heineken and that breaks to 6 beers a 12 foot rod or 1 beer per 2 feet..
I was talking to the guy up the street whose grandparents built the two story frame farm house he is living in. He told me that photos from the day show our front street as a forty foot wide stream bed and the major road on the other side of my tiny corner lot being a major named creek that is semi navigable (joke there) creek that runs 12 months but floods 4 of those months out of the year. He told me my lot was the down stream side of the convergence of those creaks. Hu Knu? I am pretty sure that the creek bed rock is ten feet down and I should be OK if I dig out to that level. Hopefully i can slide by at a more shallow depth. Of course, given my run of luck with this "house possesed from hell", my only option willl be to build the parking pad on pontoons.
There is a little dramatization in this tale of woe but only a skosh. The contractor tells me that I may, not likely though, in fact, have to put in a multiple layer base and that the bottom layers could be large and a couple feet down. He wants to put in 8 inches and "see how it goes". Remember me...Mr. Overkill?....Can't be that easy.
I haven't been able to come up with much on the "design" of the pad from the Net. You guys have provided 95 percent of what i have discovered. But I did pick up one piece of instruction on figuring the min depth of the rock I will need. Get this" Take a square cut, as in not sharpened, 2 X 2 and drive it in the ground till you have shattered it to bits. The depth the "stake" will penetrate is the min depth you need to lay in rock. Anybody ever heard of this? My gut tells me that this is so simple and un-scientific that it MUST WORK. I'll try that this afternoon.
OK, so I'm off to work on my Appleseed Processor. Hope to hear more from all of you. I am down hill from both adjoining lots and this is Orygun. The contractor never brought up drain pipe. Then there is that sewer line for the bus tanks to drain into.
Sure Pac, Geo Mat, sand with cement....the net gave me none of that....thanks.
John
A GeoMat is the only way to go. We put them under Commercial foundations and slabs to counter wet conditions. No matter what kind of rock you put in, you will constantly be adding rock every year without a mat under it.
Good Luck
Mike
JohnEd, the way we always done it on the cheap wet real estate WM bought was strip the topsoil turn over the the existing ground let it air dry compact that lay your mat down spread the road base when the store was complete lay down the asphalt I never went back on a WM parking lot and they are cheap lol the light duty paving was 6 inches of base the truck lanes were 8 inches of base with 3 inches of asphalt
good luck
For my bus parking I dug out the soil 15 inches and put in what we call processed here in Connecticut which is blasted trap rock and very hard. The processed I used was one inch with quarry dust mixed in. This is what they use under the highways and local driveways. It has not sunk in five years of being exposed to rain and snow. You might also check to see if asphalt milling is available in your area. Packs real hard. Sometimes they are just looking to give it away so they don't have to truck it far.
I liked that advice on driving a 2 X 2 stake into the ground till the stake shattered. Guessing that means till it quits sinking. As I understand it the depth that the stake drives is the depth that you need to fill with gravel. Sound right?
Remember my story about pushing a grounding rod into the soil for 5 feet before I needed to hit the metal bar with a hammer? Similar experience with WOOD. I pounded the heck out of that pine wood and i thought it wood splinter but it ever so gradually sank some 4 inches. Then I developed SUPER HUMAN powers and became Thor his-self. That stake started sinking a 1/4 inch with each strike of my hand sledge. 20 inches down and it is still sinking with every blow and showing no signs of hitting anything stiff. I am bummed.
I guess it will be easy to dig out though, right?
Any comments now that i know that 20 inches down it is soft?
Thanks,
John