Turn it off at the breaker. Strip about 1/4" insulation off each wire. Run down to Home Depot and buy one of those water-proof wire screw kits that water will not penetrate when it dries.

Come home, take the wire nuts out, twist the two ends on one color together and pour in the epoxy; Twist until tight as you can get. Then do the other one. After the epoxy sets up you'll be okay as long as none of the wires are exposed through the insulation. I would bury them if you have enough slack.

Sirwriter