On Sat, 10 Jul 2010 02:41:01 -0700 (PDT), wrote:

you trying to run power to the gate? or will the ditch be for a actual
sensor? why 4 inches wide? will it run parell to the driveway?

This is a sensor powered off the circuit board of the gate control box.
When a car drives past the sensor, it simply opens the gate.
The sensor merely needs to be buried (to protect it from heat and being run
over by the lawn mower).

The sensor itself is about two inches wide, so I figured a four-inch wide
ditch would suffice. The depth can be anything, so I was thinking six
inches was about right to protect from the elements. Pipes don't freeze out
here so heat is the problem, not cold.

used a jackhammer in areas
That might work but it seems like overkill. So far, the pressure washer or
compressor might be the best bet (although the compressor is 220v and I
don't have a 200' extension cord for it).

I was just hoping something better than the pressure washer would come up.
The advantage of the pressure washer is that I can park it on the driveway
and then walk up the slope to "cut" the line like a blow torch in metal.