Allen Steam Facility - Duke Energy (12)

To: Bethany Georgoulias
From: Rob Krebs
Prepared By: Michael Parker
July 13, 2011
NCS000546 Duke Energy Carolinas, LLC - Allen Steam Station
Gaston County
Site inspection conducted on July 13, 2011, by Michael Parker. Facility contact: Mr. Mark McGary
[phone] (cell) and Mr. Don Scruggs, Plant Manager. This request is for a new SW permit.
This facility is in the business of producing electricity via coal fired turbine generation. The SW
outfalls at this site drain to both Lake Wylie and to the South Fork Catawba River. Both Lake Wylie
and the South Fork are classified as WS -IV, B. The South Fork is listed as impaired for copper and
has documented water quality standard exceedances for temperature.
A significant portion of the SW generated from the industrial process areas at the Riverbend Steam
Station (RSS) site is routed through existing yard drain sumps that carry the SW to an existing ash
basin. This ash basin discharges through outfall 002, which is covered under the facilities existing
NPDES wastewater permit (NC0004979). There are, however, areas of the site where SW drains back
to surface waters, and these areas (and the associated outfalls) are to be covered under the subject SW
permit. The only SW testing data available for review in this application was collected in 2009 at SW
outfalls SW008 and SW0015. This data was collected in conjunction with the site's NPDES
wastewater permit renewal. There are at least 20 existing SW outfalls that Duke Energy has submitted
for inclusion into the proposed permit. Some of these outfalls are relatively easy to access and some
are very difficult to access. There are a few outfalls that would likely present a safety issue for site
personnel should analytical be required. Also observed during the site visit were a number of
"internal" SW outfalls that do not discharge directly off-site and may require some channel
modifications in order to collect a SW sample. A number of these internal outfalls discharge into
vegetated areas as sheet flow before reaching surface waters. There are also a number of outfalls
identified in the permit application that were found during the site visit that drain areas of the site that
are well removed from where any industrial activities take place. These outfalls should not be
included as sampled outfalls and are identified on the site map as outfalls: SW001, SW002, SW013,
SW014, SW017, SW019, and SW020.
In their permit application, Duke Energy has requested the following outfalls be considered as
Representative Outfalls:
• Outfall SW005 as representative of outfalls SW002, SW004, SW005, SW006, SW014, SW017,
and Group outfalls SW019.
Based on observations made during the site visit, designating outfall SW005 as a
Representative Outfall is considered appropriate for this group of outfalls even though outfalls
SW017 and SW019 enter the discharge canal instead of the Catawba River. As noted above,
SW outfalls SW017 and SW019 do not drain areas associated with the industrial activities at
this site, so it would be acceptable to include them in this representative group.

Page Two
• Outfall SW008 as representative of outfalls SW001, SWO03, SWO07, SW008, SW009, SWO10,
and Group outfalls SW013.
Designation of outfall SW008 as representative of this group of outfalls is recommended.
• Outfall SW018 as representative of outfalls SW015, SW016, SW018, and SW020.
Drainage area 18, which leads to outfall SW018 is one of the areas of this site where internal
outfalls complicates the review of this request. Furthermore, there is a perennial channel that
bisects drainage area 18, and separates the drainage area into two distinct areas. Since all SW
from drainage area 18 leaves the site at the confluence of the perennial channel and the
discharge canal (SW018), it would not be prudent to conduct analytical testing at this outfall
since any testing would not be entirely representative of the SW from this drainage area 18 due
to the possibility of off-site influences. The western portion of this drainage area is
predominately wooded with some gravel parking areas whose SW is directed via sheet flow
back towards the perennial channel. The SW from the eastern portion of this drainage area
travels through at least two internal outfalls, a closed out (vegetated) sediment basin, and then
sheet flows down towards the perennial channel. The SW from the small amount of industrial
activities that takes place in this drainage area (Dry Ash Handling Facilities) is collected and
piped back to the site's existing ash basin. In conversations with Duke Energy staff during the
site visit, it was decided that outfall SW015 would be a more representative outfall than
SW018. This decision was based on the large size of the area that drains to the outfall, the fact
that the SW from this area drains an area where fly ash has been deposited, and the fact that any
discharge from SW015 is comprised of SW from the site and not influenced (significantly) by
off-site drainage. This Office recommends that outfall SWO15 be designated as representative
of outfalls SW016, SW018, and SW020.
• Outfall SWOT I is representative of outfalls SWOI l and SW012.
The drainage areas for both outfalls SWO11 and SW012 are two drainage areas where a
significant amount of the industrial activities at this site take place. In both of these areas, there
are both graveled and paved (impervious) areas, and a portion of the SW generated in these
drainage areas passes through oil trap tanks (oil/water separators) before being discharged.
Based on observations made during the site visit, this Office has no objection to designating
SW outfall SWO11 as representative of outfalls SW011 and SW012, however, analytical testing
for all parameters should be required of both outfalls during the first sampling period of the
permit.
SW outfalls SW005, SW008, and SWOT I receive drainage from areas that have areas that are either
partially graveled or receive a considerable amount of vehicular traffic. Fines associated with the
gravel and vehicular traffic will likely be problematic for TSS once analytical testing begins. Unless
additional measures are implemented to control the off-site movement of the fines associated with the
gravel and dust from vehicular traffic, this facility will likely have difficulty in consistently complying
with the benchmark TSS levels proposed in the draft SW permit. The mobility of these particles may
also help contribute to the other elevated benchmark values noted in the analytical testing data
submitted with the permit application.

Page Three
Analytical testing data, collected in 2009, and submitted with the permit application for outfalls
SW008 and SW015 reflected a number of parameters where test results have exceeded the proposed
benchmark values for Aluminum, Chromium, Copper, Zinc, and Total Suspended Residue. Given the
large areas of gravel throughout the site, it is not surprising that the TSS levels would be elevated;
however, Duke Energy staff will need to conduct an internal investigation to determine possible
sources of the elevated aluminum, copper, and zinc levels. There have been some significant
construction additions at this site since the 2009 testing was performed, and these activities could result
in a change in the characteristics of the site's SW, which would render the submitted testing data as not
being indicative of current site conditions. One important site addition in recent years is the
construction of the Flue Gas De-Sulfurization facilities (FGD), which have now been completed and
placed into operation. As a result of the construction of these air treatment facilities, Duke no longer
has a "particulate" discharge, but releases steam as a by-product from the FGD operation. Such being
the case, it will not be necessary to consider a possible wind rose deposition analysis in the selection of
potential representative outfalls since Duke no longer releases particulates to the atmosphere.
Even though representative outfall status has been requested for a number of the SW outfalls at this
site, the lack of (recent) analytical testing data is of a concern, especially when some of these outfalls
drain areas of the site where significant industrial activities take place. Granted some of these outfalls
can be considered consistent in nature with their corresponding representative outfall, however, the
screening of these outfalls will provide beneficial data in which to base future permitting decisions and
help confirm any negligible pollutant loading. Such being the case, it is recommended that analytical
testing be performed for all parameters during the first sampling period of the permit at SW outfalls
SW002, SW007, SW008, SW009, SW010, and SW012.
In conclusion, it is recommended that the subject SW permit be issued with consideration given to the
comments/recommendations as contained in this report.
/mlp