You will have to dig out some dirt to get at the PVC pipes.I think you will have to dig to where the next "joint" or connector is down on the pipe. You then remove the damaged portion of pvc, and glue the new portion of pipe onto the old portion with a new pvc joint. Whenever my hubby works on a plumbing issue, I make sure I take my shower and run several pitchers of water. Usually the water is off a while and sometimes, if the fix doesnt work, off a long time! The key is to make sure the pipes and joints are DRY dry dry - no moisture, when gluing. One trick is to plug up the pipe with a ball of wonder white bread so no excess water can leak down the pipe and onto the joint you are gluing. Once the water is turned back on- the water pressure blows the bread plug right through the pipes and it disolves. Even seasoned plumbers sometimes have failing joints in newly glued seams with even the slightest moisture.
If u cant replace the entire lawn with groundcover, put a small flower type bed around each lamp or other item sticking up in the lawn. About 8 inches from the center of the post. Put in a very low type plant/groundcover, or even river stones(with landscaping fabric under them so weeds don't come up).
Dicondra groundcover will work for shade, but not sun.
There is a grass called mondo grass, which if I remember corectly doesn't have to be mowed. it is not as pretty as a mowed lawn though. Thyme is a nice option and it gets sweet smelling flowers on it. Talk to your nursery personnel or look up "low maintenance ground cover options" online.