Éolisa operates several wind farms. One of them, with twelve turbines, is connected to the grid by a power line and a transformer substation built by Éolisa and used only by this farm. The farm sells its output to a single buyer and its cash inflows are independent of those of the other farms (given). The line could be disposed of only for a low scrap value, unrelated to the cash flows expected from its use. A landslide has damaged the line, which is an indication of impairment. The controller proposes testing the line alone on the basis of its scrap value; the finance director proposes testing all the group's farms together. Write a judgement memo.