Repairing storm water drain blocked by tree roots:
First feed the garden hose into the drain until it hits the blockage. Then remove and laying it out along the lawn locate the dig spot. Next dig up the drain and clear it both sides. The sewer line may have been placed in the same trench so to make sure we have the correct drain we will proceed as follows. Make an incision into the very top of the clay piping as follows. Begin on the top dead center with a carpenters 4-inch nail punch. Chip away at the clay until you can begin to work outwards and then inwards again to finally break through the outer shell. Chip away at this holes walls until you can get your hand into the drain and remove all of the clay chips. Then have someone inside the house place some toilet paper in the toilet bowl and flush it away. You watch and see if it passes you by. If not double check it is the storm water by running the garden hose down it. If it is the sewer no harm done simply go along to your nearest sheet metal shop and go to their scrap bin and select out a piece of sheet metal big enough to curve over the hole and cleaning off the pipe silicone this metal cover over the hole you have created and move on to locating the storm water drain.
Once you have the storm water drain located for sure use the hose to further get an exact position on the tree roots and smash this section of the drain out of the way. Gaining two points where you have the barrel of the pipe nicely broken ready for two rubber earthenware to PVC adaptors plus a section of 4-inch (100 mm) pipe to replace the missing clay pipe section.
If the break you make is jagged simply clean it up to even for the rubber connector by using a large shifting spanner to nibble away at the clay using leverage. Place the rubber unions on the PVC pipe and lower into position move the rubbers up onto the clay ends and do up the clips with a screwdriver.