The surcharge threshold levels set forth above are not local limits. All pretreatment standards and pretreatment requirements, including the prohibition against pass-through and interference, do apply to discharges of the conventional pollutants listed above. In addition, nothing in this section shall prevent the Director from exercising his or her right, as described in §
30A-10 of this chapter, to require an industrial user to comply with specific discharge limits on these pollutants if deemed necessary to meet the objectives of §
30A-1A of this chapter. In the event that an industrial user receives specific discharge limits for any of these pollutants, no surcharge shall apply and violations of the discharge limit by the industrial user shall instead subject the industrial user to the enforcement provisions of this chapter.