Apparently you are not allowing sufficient line out . Your bump head should not be striking the rocks , you should maintain 4-5 " clearance . Also reducing your head speed will reduce line usage from excessive friction which eats up your line . I edge over 200 ' along a cement abuttment weekly and this reduces line replacement greatly . Good luck . P.S. There is high abrasive speciality line available also but rather expensive , which is for Commercial Trimmers . It may or may not fit your trimmer head . Husquarna Force or Gator Magnum trimmer line are two high quality lines designed for abrasive resistance ability .

roundup/spectricide

roundup/spectricide?

How do you control the erosion issue. While there is riprap in the ditch before the grass( ?) took over there was erosion along the outer row of rocks.

Krnuttle , huh ? lol. The herbicide will kill the weeds and grass , the riprap controls the erosion . If the rock structure has been there for any time it should be stable as should the earth . Herbicides are Carcinogenic , so don,t drink the Kool-Aid !

I avoid weed, insect and similar killer on my yard.

I would rather have a few weeds than kill off the insects and vegetation that attract birds and squirrels, that attract the hawks, foxes, bob cats, and other large animals.

Follow my directions from 2 yrs ago and move on !