what can i use for digging around sewer pipes that is lined with heavy clay

Yes, they make electric augers. Just be careful if you're looking to buy one - the one you're looking for would be called "electric post hole auger" or "electric post hole digger". Something that's sold as just an "electric auger" is usually an ice auger for winter fishing.

In addition to that, there are auger bits you can mount on a power drill, I guess it's another possibility, depending on the size of your job.

Note that these things are only controllable to a reasonable degree if they are digging straight down - for anything like a trench you are probably looking at hiring a backhoe. If it's a very small trench, they do make very small backhoes but an auger may not be the right tool for the job anyhow. Â All the above said though, is this for finding a leak? Have you investigated a possibility of hiring an inspection company that sends a special video camera down the drain to locate the leak instead of digging? Once you start digging around a sewer, things can get very messy very quickly and I would look for a solution that does not require digging before I would commit to moving any dirt.

There are also ways to repair a leak in the sewer without diggingÂ - look for a contractor in the area that offers sewer pipe lining. Â