One thing you could do, since the spawners have a limit on how many draugr they can have within range before spawning more is to dig up to three trap holes per spawner and push/drag mobs into those holes so they remain to saturate the spawners limit while being completely unable to attack(barring archers). From what I've seen, elites count as 1.5 or 2 units of the three that a spawner can have nearby so that can reduce how many you may see at any given time.

This method will allow you to leave multiple spawners alive allowing you to build and terraform the area until you can select the spawner you want to farm, and/or use the remaining spawners as backups in case you accidentally destroy the one you've chosen to farm.