Estimating Rip-Rap

[JimS]

I need to estimate some rip rap. I need to cover an area 8x21ft. The rip rap is shale 4 inch - 12 inch in diameter. I just need to cover an area on a spillway. It does not need to be to any appreciable depth. The supplier estimated 8 tons, but that sounded way excessive.

By the way $69 a ton plus $130 delivery; I'm about 10 or 12 miles away.

 

[RodinNS]

The volume sounds about right. Half a tandem load... The price sounds like an awful good rape tho. 69 dollars a ton?
I don't know where you're at or where the rock comes from but that sounds outrageous. Around here most aggregate would be in the 6-8 dollar/ton range. I don't know what rip rap would be specifically... but I think it's off by a factor of 10 unless mabey your supply comes from 'here' by boat to wherever you are.

Rod

 

[504-1]

Rip-rap is about the highest rock you can buy, quarry run is a lot cheaper but it is a lot dirter too.

 

[hoosier boy]

That is kind of high, might try another source if possible. Dont know your application but if the ditch isnt very steep you can spread it pretty thin especially if you have a textile under it. If its steep and no textile you really need it thicker.

 

[PJH]

Jim - it's hard to estimate riprap - the gradation is not very "tight". We used to use 3/4 ton per cubic yard for a VERY rough estimate. Also, we were using what they called 100 pound riprap, which is MUCH larger than what you are talking about. Regular road aggregate, (CA 6) with lots of fines will weigh close to 2.05 tons per cubic yard. The fines fill in the voids, making it heavier than a cu yd of riprap. I'd use a number between .75 and 2.05 tons per cu yd - maybe 1.5 would be a fair guess. Riprap hauling is costly - it's rough on a truck bed. I know this isn't much help.

Another way to look at it - 8' X 21' X 1 foot thick divided by 27 equals 6.2 cu yards. I'd think that would be about a tandem load. A tandem will haul 6 cu yards - if you want it a foot and a half thick - then a load and a half.

I googled riprap, and they used a number that calculated to 2.25 tons per cu yd - I KNOW that is high.

Paul

 

[ericlb]

your right about 6 cu yds for this job,, but a tandem will haul 12 cu yds easy, 14, if there are no scales on the route so about half a load, but the trucking cost will be the same, the truck will cost the same to run weather its half full or completly full, this may make it feasable to order a full load, if you are thinking of doing another rip rap project in the near future, truck load info comes from personal experience, i own one and run it dailey , almost 22 years now, still wondering why lol

 

[Billy NY]

I used to estimate based on a trapezoid shaped apron relative to the size of the culvert, so the formula for the area of that x the depth would give you the volume.

Using your numbers, 8x21x4"( 4"min aggregate size) 4/12=.33 so 8x21x.33= 55.44 cu. ft./27 cu. ft. per cu. yd = 2.05 cu. yds. x 1.5 tons of stone per cu. yd ( as per what stone is here per cu. yd ) = 3.08 tons. For smaller aggregate, 3.5 tons, (round up a little) would easily fill that area 8x21x4", only factor I am unsure is how to take in consideration of the voids (annular space)for larger aggregate, to be precise, but would assume it would take less tonnage of this material due to the aggregate size taking up more space than smaller aggregate with larger voids. Been a long time since I've estimated rubble/rip rap so don't quote me,the price and the quantity sounds high at first glance here, but maybe I'm wrong, as this material will vary per your location etc. Maybe for estimating purposes of this material type, you use the same tonnage regardless of aggregate size or or the supplier can provide that information, most around here are very helpful in figuring quantities.

Suppliers/quarries around here use dedicated rock body type trucks for the real large rip rap, smaller material like 4"-6" we used regular tandem dumps, as do most guys trucking same but with a small layer of sand or suitable fill in the bed to absorb the impact of the material, nothing worse than standing next to an empty steel dump body as the loader lets that first bucket in. Looking at the crushing operation, it would seem the larger materials require less processing, and the price per ton would reflect that, last time I ordered crushed stone, 2", clean, or crusher run like what is commonly used for road subbase, was somewhere around $11-$12 per ton delivered locally, if I recall correctly. Might be a bit more now or back then.

 

[BobReeves]

Never bought any Rip-Rap but need to.. Couple years ago before diesel went to $4.00+ I was getting Chrusher Run delivered for about $70.00 a load. When the price of fuel went up it went to almost $200. What I don't get is now that fuel is back down it's still close to $200.00. Guess they figured if they could get that much why lower it....

 

[bc]

What I've noticed about rip-rap is that it depends upon angle of slope and amount and type of drainage going into it. For highway culverts with plowed fields running into them, large rocks are used and they eventually fill in with silt. Steep angles under a bridge take big rock as well.

Sounds like a farm pond. If this was the end of the drain pipe going through the dam, I'd use a mix of rock size but probably not the area size you have. If this is a gently sloping spillway/overflow by a dam for a 100 year rain, then the smaller stuff should work. Spread some portland cement around to help stabilize it.

 

[EVILBOWEVIL]

Rod in central ohio aggregate runs 13 a ton and up plus trucking. don't remember what the riprap cost last time wasn't double though. use limestone here can get it local at the pit
ron

 

[Flurette Farm]

Strange how those things work isn't it. ......

 

[glennster]

i bought 8 semi loads of rip rap about 2 years ago. right about 24 dollars a ton delivered. quarry was about 18 miles away. that is some fun stuff to move!!!

 

[MeanGene1]

Just happen to be an engineering estimator, and have placed a lot of riprap in the past, lots with a backhoe, and spent five weeks straight setting rock up to 12' across with a CAT 345 equipped with a thumb. 8'x21'x1'= 168cf / 27= 6.22 cy x 1.2 tn/cy = 7.47, or 8 tons- like they said. You need to figure the minimum thickness by the largest rock size in the range, or 1'- you can't spread 1' rock, 4" thick. 1.2 ton/cy is what we use for Caltrans No.2 Backing Rock, which is similar to what you're using, and accounts for the voids. A backhoe with at least a 2' bucket works very well, and with a little practice, you can make it look real good. Don't use a bucket over 3' on a rubber tire hoe, or you'll tweak it out of shape setting the rock

 

[Anonymous-0]

Before I paid 69 dollars ton, I would have the local sidewalk contractor haul me out a load of broken up sidewalk. Ripe/rap in Iowa about $8.00 ton.

 

[Leland2]

around here broken concrete is free as contractors are looking for a FREE place to dump it