After reading most of this, if you only need to haul 5 tons 5% of time (15 times a year), buying a dump trailer and the right hitch may be a poor investment unless you find a great deal on a used one. If the supplier is only 15 miles away, I doubt he will charge more than $50 per load to truck it. Driving your own vehicle will cost about $15...so the additional cost to have it delivered will be $35 per load.
Take the $10k you will spend on a new dump trailer, invest it at 4% and you come out ahead. If you need to finance the trailer, the numbers are even worse.
Well, this is exactly what I've been thinking about, the ROI on it. I can get 20 tons delivered for ~400 dollars, or, at the quarry, it's about 1/2 that price (220). Each 20 ton load is 4 trips with a dump trailer, so, every 40 trips with the dump trailer saves me 10 load fees, ~2000 bucks. So I'd need to do about 300 tons before I hit a break even on just crush and run (120 trips). Wow, that's a lot of back and forth, but in miles terms, it's not that bad (120 trips, figure 30 miles round trip each time, ~4000 miles). However, just seeing that number "120 trips" seems a bit daunting. I guess if I split it up a bit and think about how I'd do this, it's only a month's worth of 4 trips a day. Still seems like a lot though! I've gone through about 150 tons of crush and run so far, and I probably have another 200 or so in direct line of sight for planned projects. Still though, just thinking about it, 200 tons is only 10 truckloads, I can get that dropped here in a day by a guy with a truck.
Part of this is that finding the "guy with a truck" and getting him to, you know, call me back/show up/deliver on time to the right spot is a bit of crapshoot. Also, there are other things I could save on, I usually get a tri-axle or 2 of mulch a season, I'm sure I could do pretty good hauling that myself (I think the limit there is volume, not weight).
I think I've known for awhile that the financials don't look great for dump. It's more about the convenience of it, if the quarry is open, I can roll on over there and get 5 tons, no notice, no coordination. In the truck, 10K of rock at the property in <1hr (for 55 bucks!). But maybe this is one of those things where the thought of it sounds better than the reality.
Also, figuring in I have to take the value of the used dump trailer into account. They seem to lose almost no value if they are kept in decent shape, I've been looking for a used one for a long time, none of them make sense because the prices are too close to new. So, assuming I decided to sell it in a year or 2 (doubtful, but, hey, it's part of the financial consideration), I have the feeling the numbers would start to look real good, even hauling 100 tons of stone, I'll bet I'd hit near break even (doing 20 trips to the quarry, saving 1000 in delivery fees, I could probably resell the trailer for 1000 less than I bought it for at that point).
Of course, that doesn't take into account the wear/tear on the truck.. And that could be substantial.