For induction problem you should be checked the grounding system.
But about RF subject, i can say:
Near the high voltage line the radio noise interference due to its corona and some else high voltage phenomenon is possible. The noise frequency band which shall be considered in this case is 0.5 to 30 MHZ. The frequency of 0.5 MHZ (or 1 MHZ) is considered because usually, the level of radio noise at this part of the spectrum is representative of the higher levels. Also because of the possibility of error due to the presence of standing waves (refer to dimension of noise receiver device), the following frequencies: 0.5, 1, 1.5, 3, 6, 10, 15,and 30 MHZ are important. But the frequency of data transferring in the computer system is near to 100 MHZ; therefore the possibility of interference between two systems is low.
On the other hand, the distance of measurement to determine the lateral profile of the radio noise field is 20 m. As you see this distance is very lower than your mentioned distance (65 m).
For accurate information you can refer to BS5049.