Drain pipe has 40 PSI rating.
Can you calculate the RPM and the Diameter of the Turgo ?.
Joe can assist you there, well,
It may be necessary to have a special Turgo plate.
Since you are planning to use a Smart Drive and the distance is 500 Feet let me suggest NOT to modify the S&D windings and leave them as coming from the factory.
Use 3 transformers to bring the Voltage down to the necessary voltage ( 65 to 85 Volts) and use a MX60 to attain the maximum power available.
A bit more expensive but the power harvesting would be at its maximum.
To get the 1000 watts you will need to run the S&D at around 1100 RPM, so get a motor(1.0, 0.8 or 0.60 Size ) that gives the output voltage the transformers need.
This way the transmission loses would be at a minimum and a # 12 Size, 3 wire will do the job, wire that is a commodity throughout the world
Regards
Nando