Erosion control is usually devices to contain/reduce sediment from leaving the site - IE: silt fence, wattles, check dams, sediment ponds, etc. Grassing, hay mats and hydroseeding are usually referred to as soil stabilization. Now that is just my experience with the terms in my neck of the woods. I would definetely check out exactly what they mean by that because 1,300,000 quantity sounds like grassing. I do know from experience that erosion control and site stabilization can eat your lunch if you do not understand what the scope of your responsibility is on the project. Every budget/bid that I do, I add more $$$$ to this line item than the last similiar project.
BTW - I am about to get an expensive education in exactly what the EPA Clean Water Act rules require.:Banghead
If the bid is for erosion control, like silt fencing, the going rate here is around $4 per FT, labor and material installed, DOT CL II wire backed with metal posts. Rock checks and the like need to be priced out at the equipment rate of the piece needed plus the delivered cost of the stone. Grassing and hydroseeding can vary tremendously ($1500-$3000 per acre or more depending on specs) - I would get a quote on that. Also erosion control maintenance needs to be a line item in your bid. When the weather drops 1" of rain in a couple of hours and you need to clean/replace the silt fence, you need some money in there to cover it. Unfortunately this is, at best, an educated guess - who really knows what the weather will do.