It would vary by terrain and land use (e.g. agricultural), but generally just 2-3 feet deep by vibratory plow. Deeper emplacement and directional drilling were

It would vary by terrain and land use (e.g. agricultural), but generally just 2-3 feet deep by vibratory plow. Deeper emplacement and directional drilling were used as required to handle obstacles. For most L-carrier the entire en-route infrastructure was below ground, but it was more extensive than just the cable, with active repeaters in manholes required at 2-mile intervals for L-4. L-4 also required an "equalizing repeater" about every 50 miles, which was installed in a manhole but had a shed on top to facilitate technicians adjusting the equalization. Main stations, such as this one, were required every 150 miles.