FEDERAL ENERGY REGULATORY COMMISSION Project No. 405 ...

20100204-3055 FERC PDF (Unofficial) 02/04/2010
Project No. 405-087 3
For Task 2, Exelon proposes to sample the discharge boils of the operating
turbines when Conowingo Pond is stratified primarily from July to August 2010. The
goal of this task is to determine if the compliance monitoring point (station 643) is
representative of actual DO levels that the project discharges during all modes of
operation during a historic period of higher temperature and low DO. This period
historically corresponds to flow less than 10,000 cubic feet per second (cfs) and water
temperatures greater than 75 degrees Fahrenheit ( o F). Discharge boils would be sampled
for temperature and DO over the course of two consecutive days from 6:00 a.m. to 6:00
p.m. The agencies have requested sampling the discharge boils from operating turbines
during the entire period of historic low flow and higher temperatures (July 2 through
August 30, 2010) from 6:00 a.m. to 6:00 p.m. for two consecutive days on Friday and
Saturday of the first week and Sunday and Monday of the second week regardless of
stratification in Conowingo Pond, river flow or water temperature according to the
following schedule in order to better understand the impact of a variety of project
operation modes on DO.
Friday/Saturday 7/2 & 7/3; 7/16 & 7/17; 7/30 & 7/31;8/13 & 8/14;8/27 & 8/28
Sunday/Monday 7/4 & 7/5; 7/18 & 7/19; 8/1 & 8/2; 8/15 & 8/16; 8/29 & 8/30
While we agree with the agencies sampling approach, modifying the study to
sample mid week on a few occasions over the course of the study would better represent
variations in project operation since periods of higher electricity demand occur during
mid week rather than on weekends. Therefore, we recommend modifying the agencies’
recommended sampling schedule to include monitoring for two consecutive days mid
week (Wednesday and Thursday) once each month during July and August according to
the following schedule to better capture variations in project operation.
Friday/Saturday 7/2 & 7/3; 7/16 & 7/17; 7/30 & 7/31; 8/13 & 8/14;8/27 &
8/28
Sunday/Monday 7/4 & 7/5; 8/1 & 8/2; 8/15 & 8/16;
Wednesday/Thursday 7/14 & 7/15; 8/25 & 8/26
Comments from Maryland DNR, SRBC, the Fish & Boat Commission, and
Pennsylvania DEP also state that Exelon’s proposed sampling schedule for the discharge
boils has the potential to exclude manual DO sampling of the discharge boils. Based on
historic river flow and water quality data, it is unlikely that river conditions during the
July through August sampling period would not be suitable for sampling the discharge
boils. However, we believe that Exelon has placed too many conditions that must be met
before initiating the discharge boil sampling program which could limit the amount of
data collected for this portion of the study. A reduced data set has the potential to limit
the statistical evaluation of whether station 643 is a representative compliance point.
Therefore, in order to provide sufficient data for the Task 3 statistical analysis, the study