Grinnell Industries of Woodruff's Gap (Sparta) has recently had a siding installed to service their facilities. They apparently specialize in paving stones, gravel etc. Don't know how many cars or how often they ship out/in yet. The L.H.R.Ry used the lands in Woodruff's Gap for harvesting gravel for ballast in the early 1900's and also shipped out large quantities of rock products to build the lower deck of the GW bridge in the 60's (via the D.L.W. ). There are now 2 solid custmers with sidings in Sussex County for the N.Y.S.W. Hopefully we'll see more trains in N.J.!
Actually...
Its probably not for hauling anything having to do with the paving stone business.
That big building in the background of your photo has a name on it for a local politician with "Recycling Center" or something to that effect. So my guess is they will be hauling construction debris and/or garbage out of the facility.