Rule 325. In addition to the requirements contained in 49 C.F.R.§192.705, which is adopted by reference in R 460.20606, at intervals of not more than 6 weeks, but not less than 12 times each calendar year, an operator shall patrol all transmission lines that are operating at 40% or more of specified minimum yield strength to observe surface conditions on, and adjacent to, the transmission line right-of-way for indications of leaks, construction activity, and other factors affecting safety and operation.
Mich. Admin. Code R. 460.20325