Section 658-14-4 - Underground Tanks14.4.1 Underground tanks must have the requirements of Section 14.3, subsections (1)-(3), clearly marked on the inside of the dome cover.14.4.2 Underground containers must be installed such that the top of the attached dome is a minimum of six (6) inches above finished grade.14.4.3 Existing underground tanks installed prior to 2015 must be tested for corrosion protection in accordance with the corrosion protection requirements of NFPA 58 including schedules for continuing testing.02-658 C.M.R. ch. 14, § 4