A variance is valid for such time and under such conditions as the Board of Appeals determines in its decision. A variance shall not take effect until the Town Clerk has certified, pursuant to MGL c. 40A, § 11, that no appeal is pending. Failure to comply with a variance during development, operation, or use will result in a penalty of $300 for each day of continuing violation, revocation of the variance, or judicial enforcement pursuant to MGL c. 40A, § 7, as amended.