It is normally not required by any residential plumbing codes to flush and chlorinate or shock the system when doing normal repairs or replacement of residential piping or fixtures.

Unless you have unusually strict local plumbing code requirements in Massachusetts you can do what you propose without any chlorine at all.

All that would would be required is to run the well water until 'clear'.

This can take 6 hours or more.

Call you local plumbing code office to be sure what they require.

Just don't drag the pipe and pump through any dog/bird poop in the yard while you are removing it and installing it... Oh, wait, perhaps a little bleach wouldn't hurt that much after all.

Thanks, guys.

It made no sense to me that that it would be so universally recommended to shock the entire plumbing system simply because the pump was swapped out.

I concede, I may have been lucky that I didn't introduce any nasty bacteria during the first two repairs.

I might try running a roll of kraft paper across the lawn to lay the pipe on or may throw some bleach down there and just pump it out from the pitless adapter across the lawn.