Water Jet Pop-Up Valve Black Cover Damaged and Leaking

The top of the black cover has a short metal strip attached to it. While trimming the grass around it, this little strip got a small nick to it...resulting in water shooting out of it like a water gun. Can I just duct tape it or something? Please help...

Is this for a lawn sprinkler system? Sorry, but you won't that kind of info here on the forum. If this is something pool related, please explain a little more.