DOE/ORO/2327 Oak Ridge Reservation Annual Site Environmental ...

Oak Ridge Reservation
Practices Plan, and a Radiological Monitoring Plan. The WQPP will be reviewed, and if appropriate,
revised annually, and submitted to TDEC for review and comment.
To prioritize the stressors and/or contaminant sources that may be of greatest concern to water
quality, and to define conceptual models that would guide any special investigations, the WQPP strategy
was defined using EPA’s Stressor Identification Guidance (EPA 2000). A summary of this process is
shown in Fig. 5.17. The Stressor Identification Guidance involves three major steps for identifying the
cause of any impairment:
1. list candidate causes of impairment (based on historical data and a working conceptual model),
2. analyze the evidence (using both case study and outside data), and
3. characterize the cause.
Fig. 5.17. Diagram of the adaptive management framework, with step-wise
planning specific to the ORNL Water Quality Protection Plan. Adapted from
EPA.
The first two steps of the stressor identification process were initiated in 2009; focusing first on
mercury impairment (Fig. 5.18), and then on PCBs, since mercury and PCB concentrations in fish from
White Oak Creek (WOC) are at or near human health risk thresholds (e.g., EPA ambient water quality
criteria and TDEC fish advisory limits). Some of the major sources of mercury to biota in the WOC
watershed are known, providing a good basis from which to define an appropriate conceptual model for
mercury contamination in WOC. A list of potential causes of PCB contamination was also developed.
After listing potential causes and analyzing the available evidence on mercury and PCB
contamination in the WOC watershed, it was clear that additional investigation was needed to complete
the third step of the stressor identification process, “characterizing the cause.” Special investigations were
5-42 Oak Ridge National Laboratory