I got tired of opening this damn thing every 10 mins and looked around at other mods to solve the issue. They all either added extra entrances, which need patches for Open City mods that the author never made, or they tried modifying the Papyrus script to force it open. Which doesn't work when leaving the Cistern due to the Havok event attached to the animation.

So here's a modified mesh that locks the animation at 4 seconds (aka. Open) and removes the Havok stuff completely.

Works with all mods. And yes, the opening sound is gone too.

Enjoy!

* = SR Exterior Cities users need a small ESP to remove an occlusion object.