Sump pumps are running every 2 minutes, city stated that in 1970 sewer was installed and it is possible that old septic was not caped properly. Any ideas on how to find old leach bed or train tiles

Sump pumps are rarely connected to a septic field. The cities answer does not make a bit of sense. Are the sump pump pits connected to floor drains or to a foundation curtain drain? When all fixtures are not in use check your water metter. Look closely at the little arrow pointer, is it moving even a bit?