Any Excavation Professionals Feel Like Giving Advice?

[sunandsand]

This thread could not have appeared at a better time for me.

We're doing about a mile of light duty road in a small development - 15 homes on 35 acres. The roads need to support cars, UPS/Fedex trucks, and . . . light aircraft. It is a hangar home fly-in development.

The airplanes are not heavy at all, but we cannot have any loose material on the roads/taxiways. Issue is that a propeller generates tip votexes which will lift loose gravel and outright ruin the prop in a very short time. The runway is turf, so no problem there, but the city *insists* on roads of some sort, so we have to pave them with something.

This gives me some of the information I need to select a bidder on the infrastructure. I will now have some (slight) idea what they are talking about and how to evaluate their bids.

(What I ought to do is consult with PaulSHarvey, he's only about 100 miles away . . . ;-)

Best Regards,

Mike/Florida

 

[bgr]

Many thoughts from many experienced contributors. I am attempting a general summary of ideas. Feel free to correct and fine tune.

1. Remove organic material down to base soil. Assuming this will be about 8 inches.
2. Use stabilizing fabric if base is not always completely dry. It may prevent trees from growing over the long term, too.
3. Use a base course of 2-4 inch stone about 6 inches deep. Make surface close to level. 1% slope.
4. Install drainage of some sort for the hole you excavate to prevent holding water when wet. Perforated pipe or a notch in the backfill against the edge of the stone on the downhill side. This is extra important if you get frost in the winter.
5. Make all of the rest of the material to top grade out of 1 minus material with fines in it which will pack and penetrate stone base and can be compacted. Should be 2 to 3 inches above surrounding soil surface.
6. If you want a stone topdressing for appearance and cutting grit on shoe soles, make sure it is not deep, should be 1 inch thick maximum to prevent tires making ruts.
7 Use excavated organic material to blend grade against the edges of the parking lot on sides where it is above grade.

OK guys, have at it.

For the poster with the roads in the fly-in development, perhaps you could use the cement or plastic reinforcing grids with grass growing in topsoil infill on top of standard road construction. This would provide a grass surface. Who can tell us about maintenance and durability for that surface?

 

[SnagDump]

Well this has turned into a wild and free roaming discussion. Here are a couple insights that may or may not have value. As others have noted, a numerical code (#57 aggregate, #8 screw, #6 wire etc.) sheds absolutely no light on the size of the object in question unless you know the code. Regional lingo only adds to the confusion when there's a national discussion (like this one).

Most aggregate codes for road construction have a foundation in AASHTO (American Association of State Highway and Transportation Officials). One of the attached tables is from Ohio but it uses AASHTO coding. Note that this table is for coarse aggregates or base course material and these are "open graded" meaning the small particles do not completely fill the spaces between the larger ones and as such they don't set up all that well. They are not great for directly receiving traffic though a layer of the finer specs on top of coarser ones would likely work OK for a parking area - not so much for a road surface.

Contrast the AASHTO coarse aggregate table with the other one from US Forest Service. These gradations are for the surface course of aggregate (gravel) surfaced roads and this is the layer intended to see traffic. You'll see pretty quickly that the surface course gradations have a lot more fine material ("dense graded") intended to fill the spaces between the larger particles and interlock. Sieve testing is particularly important for aggregate intended for surface courses so you don't end up way long or way short on some of the sizes. When that happens you get a road surface of marbles when short on fines or it ruts when too long on the finest material.

Here's an interesting bit of history since the Romans have shown up in this discussion. The Romans were quite aware of the need for compaction. Our present day "sheepsfoot" roller designs grew from the Romans practice of running bands of sheep back and forth over areas to be compacted.

 

[MGP4506]

I am in the process of talking to a few local excavation companies in regards to a project. It's a simple project (they all have said this), but each has their own method of completing the project. I've been wanting to get this project done for a while now, and life keeps on getting in the way so I will be hiring this one out to a professional.

The project is a 30' x 30' gravel parking pad. The area where it will be installed is currently grass and soil. The area slopes approximately 1.5' right to left over the 30' area and 1' front to back over the 30' area.

My question is: is there truly a "right" way to do this?

One guy said he would strip the soil down to clay, use #1 and #2 limestone as a base, then top dress with #57 limestone

One guy said he would strip the soil down to clay, use geo-textile fabric, use #1 and #2 as a base, then top dress with #57

One guy said he would NOT strip any soil, use asphalt chunks and grindings as a base, the top dress with #57 lime stone

They all claim that their way is the "best" way.

So, I am seeking an outsider's opinion which method seems the most logical to go about this project.

Thanks

#3 is out. Never leave the topsoil. The other 2 depends. Is the area wet? Any underground springs?... # 2 sounds like he is right on. Putting fabric down will help hold the rocks in place. Doing a base with larger stone and going progressively smaller stone on top is the best. If you are leaving the top stone and not a concrete pad I would look into using ground blacktop road millings, put down with a paver under heat.

 

[aircommuter]

I read all the replies and the initial description. I was in the business of building roads, building pads (certified and tested), underground utilities and other infrastructure. Much of my equipment was bought used and restored by me in the winter. My education was engineering books, plans and on the job experience. Yes I have a state general engineering license.
There are some things here that are unknown and assumed. First is the pad accessible from one side? Two sides? Or?
Then the clay talk, is that known for the area? Is it assumed or discovered by testing? Is it wet heavy clay? Is water perched on the clay? How thick is the clay? Once these assumptions are removed I can supply a proper method.
I also built one of my houses on a private taxiway community. The taxiway was there before I was. It was lighter duty and that was a mistake because people drove everything on it including concrete trucks to build their hangars. In some areas the largest piece of asphalt was 3” square. So for the taxiway person keep this in mind.
I also built this house like it was my last one. My wife and did the work over 8 years with only a sub for Sheetrock. We made all the cabinets and doors from solid teak. We had over 80 cabinet doors and exactly 80 drawers plus 22 people doors with 4 each ball bearing hinges. However the area became too crowded for our desires and we sold it 18 years after buying the lot. But unlike what others said about kids selling the house we did. This was the third time. Not counting our labor we made a clear profit of $780k. So there is benefit in building like it was forever. The house still holds the record sales price 15 years later in the area.
Back to the parking pad, once the assumptions and missing information is available I will try to help with my methods used where I am located. Every job we did was inspected and tested by a soils engineer with a geotechnical stamp, not just a civil engineer. This pad would not be something that would that needs that much attention but some of the methods within reason would be good to employ.

 

[alpha&omega]

#3 is out. Never leave the topsoil. The other 2 depends. Is the area wet? Any underground springs?... # 2 sounds like he is right on. Putting fabric down will help hold the rocks in place. Doing a base with larger stone and going progressively smaller stone on top is the best. If you are leaving the top stone and not a concrete pad I would look into using ground blacktop road millings, put down with a paver under heat.

I’m not trying to highjack the OP’s topic, but this relates with regards to site prep.
How would this work if your site does have underground springs? You obviously can’t dig out the topsoil without having the holes fill in with water and you’re not going to dig down to anything except clay and more water. Would you have to use a different method?

 

[aircommuter]

I’m not trying to highjack the OP’s topic, but this relates with regards to site prep.
How would this work if your site does have underground springs? You obviously can’t dig out the topsoil without having the holes fill in with water and you’re not going to dig down to anything except clay and more water. Would you have to use a different method?

Exactly why I asked the questions above yours. Once answered then I can advise.

 

[Merck]

I am in the process of talking to a few local excavation companies in regards to a project. It's a simple project (they all have said this), but each has their own method of completing the project. I've been wanting to get this project done for a while now, and life keeps on getting in the way so I will be hiring this one out to a professional.

The project is a 30' x 30' gravel parking pad. The area where it will be installed is currently grass and soil. The area slopes approximately 1.5' right to left over the 30' area and 1' front to back over the 30' area.

My question is: is there truly a "right" way to do this?

One guy said he would strip the soil down to clay, use #1 and #2 limestone as a base, then top dress with #57 limestone

One guy said he would strip the soil down to clay, use geo-textile fabric, use #1 and #2 as a base, then top dress with #57

One guy said he would NOT strip any soil, use asphalt chunks and grindings as a base, the top dress with #57 lime stone

They all claim that their way is the "best" way.

So, I am seeking an outsider's opinion which method seems the most logical to go about this project.

Thanks

I am not a professional in excavating but I know how to do most things. I would level the sight. Compact the soil well, then put landscape fabric down to stop the weeds from growing. As far as a base I wouldn't use one for myself. I don't think it is necessary. Just make sure the sight is level. You will need to make a perimeter to keep the gravel in place. AT least 4x6s fastened at the corners with half inch rebar. You can look online to see how thick the gravel should be. I think 6 inches would be enough but not sure on that. As far as the amount of gravel, You figure that by this formula. Length X Width X Depth then divide by 27 and then multiply by 1.4. That will give you the number of tons of gravel you need. I would add 10% to the total. You may need to use concrete perimeter to hold the gravel with the weight of a car on it. I have never done a parking lot but it is not rocket science. Compac the gravel after it is in and have it even with the top of the perimeter. That is the way I would do it, but everyone has an opinion. I would use 3/4 inch gravel. I think that is a number 8 but not sure. Good luck. I don't think my way is best. It is just the way I would do it for myself.

 

[Elroy1986]

It’s true. There a several acceptable methods. Use Geo fabric, woven. It’s used for gravel roads to prevent losing gravel by it sinking deeper into the ground. I think you could add a geogrid for added support. Stone with lock into place better. As an alternative you could use geocell products which could be expensive. Just depends on which product you choose.

I prefer the strip down to clay. But minimally strip the organic material away.

4” of 3/4” top (Geo web goes here)
Geogrid goes here
4” of 2” to 3”
Alternatively 2” base material
Geo fabric
Some say put base material here.
Clay ground

Engineers design this stuff. Contractors BS you to do it their way. If you hire out, research the tar out of who you hire. Lots of crack pots out there.

If you were close to me I could do it cheap the right way. I used to be a civil engineer designing infrastructure. Lots of experience.

There are specs you can get hold of from city government. That’s a good source. Sometimes governments live to overkill. But the recommendations to use woven Geo fabric and geogrid is definitely a good idea to save in the long run as well as make it more stable.

Parking lot could be regular vehicles or bid trucks or tractors. My method is best for the heavier traffic. As far as grade or slope goes. 5% slope is probably the limit. It just depends on how picky you want to be. I like level because it’s all gravel/rock. Angular/crushed rock. Do not waste money on pea gravel if it’s utility you need. That’s stuff shifts way too much for my preference. Instead use 1/2” to 1” crushed stone. The thing about opinions is that everyone has one. But the one you want to use should come from someone who actually knows what they’re doing backed by customer recommendations, reputation, insurance.

Just my opinion.

 

[tonynz]

I am in the process of talking to a few local excavation companies in regards to a project. It's a simple project (they all have said this), but each has their own method of completing the project. I've been wanting to get this project done for a while now, and life keeps on getting in the way so I will be hiring this one out to a professional.

The project is a 30' x 30' gravel parking pad. The area where it will be installed is currently grass and soil. The area slopes approximately 1.5' right to left over the 30' area and 1' front to back over the 30' area.

My question is: is there truly a "right" way to do this?

One guy said he would strip the soil down to clay, use #1 and #2 limestone as a base, then top dress with #57 limestone

One guy said he would strip the soil down to clay, use geo-textile fabric, use #1 and #2 as a base, then top dress with #57

One guy said he would NOT strip any soil, use asphalt chunks and grindings as a base, the top dress with #57 lime stone

They all claim that their way is the "best" way.

So, I am seeking an outsider's opinion which method seems the most logical to go about this project.

Thanks

I favour the "build up" approach as this ensures that water ponding will not be an issue. The area has been well compacted over theyears so digging down does not seem to have much merit. Probably cheaper too.