In all cases, civil penalty assessments shall be paid within 30 days of receipt of a Notice of Final Assessment. Failure to forward the full amount within this time shall result in a loss of any right to contest or otherwise appeal the penalty amount, or the violation on which the assessment is based. The Bureau shall place all penalty payments in escrow pending expiration of appeal deadlines or final resolution of any challenge to the violation or penalty amount. If the final decision upon appeal results in elimination or reduction of a penalty, the Bureau shall refund the amount within 30 days, with interest from the date of payment into escrow to the date of refund at the rate of 6 percent. If the final decision upon appeal results in an increase in a penalty, the person shall forward the full amount to the Bureau within 15 days of the decision.