NC0003425_Other Agency Documents_20210625 (2)

Responses to Comments for Roxboro Steam Station
06/23/2021
Comments from SELC
1) Comment: Add Treatment System Performance Standard.
Response: The optimization requirement will be incorporated into the permit,
but without the numeric quarterly limit for Selenium since the Roxboro
treatment system is relatively new and we don't have the long-term performance
data for this system. Numeric limit was included in the Belews Major
Modification because Duke has gained experience in operating the system over
several years and is capable of reliably achieving prescribed quarterly average
limit of 12 pg/L for Selenium.
2) Require treatment technology -based limits for Outfall 002
Response: The Technology -based limits are already incorporated into the
permit. The effluent limitations in the permit are established in accordance with
the existing federal and state rules and regulations. EPA has recently updated
40 CFR 423 and after reviewing parameters of concern established TBELs for
several of these parameters. The EPA decided that TBELs for all parameters of
concern are not necessary because "Effluent limits and monitoring for all
pollutants of concern is not necessary to ensure that the pollutants are
adequately controlled because many of the pollutants originate from similar
sources, have similar treatabilities, and are removed by similar mechanisms.
Because of this, it may be sufficient to establish effluent limits for one pollutant
as a surrogate or indicator pollutant that ensures the removal of other
pollutants of concern."