| In the first place, you do not have a 70 degree slope. Such slopes are a rock cliff or if, of dirt, are falling down with exposed soil, no vegetation of any kind. Not knowing what your slope really is like makes it impossible to make any suggestion for remediation. If you care to, the graphic below shows how a home owner can measure slopes that are not too high so you and others can tell what you have to deal with. You need a pole taller than the slope is high. A 10 ft joint of plastic pipe will do, or use two joined for taller slopes. Tie a string to a point on the pole that will be higher than
the slope. Use one that is light in weight to reduce sag. With the pole at the toe of the slope stretch the string over the top of the slope. Attach a string level to the string as shown and raise or lower that end until it shows level. Measure dim. Y. Lower the pole and measure pole to string, dim. X. X minus Y = slope height. Next measure the run distance of the slope. 
If you have to use two pipes and they bow too much, use a second string to brace the top of the pole as shown. If you don't know what a string level is, go to the link below to see one. |
Here is a link that might be useful: string level
