... I was told that unless the organic matter within the top so many inches were removed, then soft, spongy, eventually muddy areas would develop in the driveway and I would be sorry for not doing it right the first time. That to do the job right, 4 to 6 inches should be removed, replaced with stone, then topped with modified (sometimes called quarry run?). Since 4-6 inches 12 feet wide over 1000 feet is a lot of material, I wonder if my equipment is too feeble or it will just take too long to do, or not worth the wear and tear on the machines, or not be able to do the job properly (nicely pitched, level surface).
First it's important to know where you are located. A road that freezes isn't built the same as one that never sees any snow. It's also important to know what type of soil you have where you are building the road.
Grass cut short is fine if you have a solid soil like clay, sand or gravel that it's growing in. For those conditions, you don't have to do anything to the soil, and in allot of instances, you can cause more problems by removing dirt and then replacing it with gravel. The reason is that you want the gravel to create a solid survace when it becomes compacted. If it's not high enough over the existing land, then water will pool into the rock and underneith it. This is the biggest cause of failure on all roads, except for those that are not thick enough to start with.
If you have a loam type soil, then you have to remove it. There might be a rule of thumb on how deep you have to go, but I know of those who have taken out over a foot of it and where going to take out more. Some places have very deep top soil. The Pacific Northwest is famous for this. If you have to take out feet of soil, then it's allot cheaper to replace that soil with clean fill soil. Rock is more expensive then good fill dirt. I added a thousand yards of clay to my driveway to build it up for an even crown and to replace a swampy, wet area that rarely dried out.
Why are you making it12 feet wide? That's nice for cities and highways, but for a driveway, ten feet is plenty and you can get away with 8 feet if it's just your own personal vehicles. Of course, some areas reaqure a certain width for emergancy vehicles, so that would be the final call on how wide it has to be. But like you mentioned, 12 feet wide for a thousand feet is allot of material to have to buy. Cut it down to ten feet and you save 1/6th of the expense.
For the road to last, you have to have a way for the water to get away from it as quickly as possble. Trenches are the most common method for this. Wide and shallow are the most attractive, but sometimes you have to work with the space you have available. Standing water will always be an issue, so be sure to address that before anything else. Drainage, drainage, drainage is the three secretes to a good road. The rest is pretty basic, but you HAVE to get rid of the water.
Be sure you have at least 4 inches of rock. The rock has allot of differnt names all over the country, but it all does the same thing. It should be in size from very fine, almost dust like to rocks several inches in diameter. The rock has to have sharp, jagged edges so that when compacted, it wil all interlock and form a solid mass. At 4 inches, this will be strong enough to support any size load that you will drive across it and also shed water when it rains.
Never drag a finished road to smooth it out. All this does is thin it down and break up the compaction, which will speed up the process of failure. If done right, you should have to add rock to it about every five years, depending on traffic usage. When adding rock, it's a good idea to break up the existing rock so it will all compact again into one solid mass. When a road develops potholes or low areas, then add new rock to that area. NEVER drag existing rock from the road to fill a low area. That just makes the area you draged the rock from weaker. When adding rock to a pothole or low area, break up the existing rock so that it will bind with the new rock and then compact it.
Your tires will compact the rock over time. If you are paving it or expecting sever weather right away, you should roll the rock or at least run a vibritary compactor over it. If you have good weather and are not paving it, then just driving over it with your auto or tractor a bunch of times will get it done. I like to put a load of dirt in my loader bucket and drive over the area I'm compacting with my front tires. This works great on gravel patches and holes that I'm filling on things like stumps that I've removed.
A dozer is not the best tool for spreading gravel. In fact, it's near the bottom of the list for this. The best tool would be a grader. Most of the gravel guys around here also have a grader for this. If you want it smooth and level, that's the tool for the job.
The use of fabric seems to be popular in the norther parts of the country, but here, the only time I've seen it used is on wet conditions when speed is more important then money. On a solid base, gravel will not sink into the dirt. It will float over it and form a solid mass.
Good Luck,
Eddie
