The I2C bus will not work at that distance. I am afraid you will need and Arduino board such as a pro-mini local to the sensor. Then you could use software serial for communications via a pair of RS485 breakout boards such as the Sparkfun Transceiver Breakout - RS-485 BOB-10124 to the second Arduino board. If you can supply power locally to the sensor and Arduino board, you can eliminate wire entirely with a pair of SparkFun RFM69 Breakout (915MHz)
WRL-12775 boards for an RF data link.