2016-05-13 Parette Expert Report- Buck Site - 05-13-16

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MATSON
ASSOCIATES
Opinions on the Appropriateness of Monitored Natural Attenuation
in Coniunction with Cap -in -Place at the Buck Steam Station,
Salisbury, NC
Prepared for:
Southern Environmental Law Center
22 South Pack Square, Suite 700
Asheville, NC 28801
Prepared by:
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Robert Parette, Ph.D., P.E.
May 13, 2016

Table of Contents
I. Qualifications...................................................................................................................................1
11. Scope of Wo k.................................................................................................................................1
III. Basis of Opinion...........................................................................................................................1
IV. Methodology...............................................................................................................................1
V. Backg ound.....................................................................................................................................3
A. Coal Ash and the Buck Site...........................................................................................................3
B. Monito ed Natu al Attenuation (MNA)........................................................................................4
VI. Opinion: Monito ed Natu al Attenuation is not an app op iate emedy fo constituents of
inte est (COls) at the Buck site................................................................................................................. 8
A. When MNA is based upon adso ption of COls onto p ecipitated i on and manganese oxides, the
utilization of MNA in combination with capping is p oblematic as conditions fo MNA a e less
favoable following capping.................................................................................................................8
B. Kd values dete mined in the labo ato y cannot be eliably utilized as a means to demonst ate
site-specific attenuation at the Buck site..............................................................................................9
C. MNA should have not been selected as a potential site emedy fo antimony, ch omium,
hexavalent ch omium and cobalt.......................................................................................................10
D. MNA is not app op iate at the Buck site fo vanadium...............................................................11
VII. Refe ences.................................................................................................................................13

I. Qual f cat ons
I am an Envi onmental Enginee (P.E.) at Matson & Associates, Inc. (M&A). My academic
backg ound includes a B.S. in Chemical Enginee ing f om Wo ceste Polytechnic Institute and a
M.S. and a Ph.D. in Envi onmental Enginee ing f om The Pennsylvania State Unive sity. I have
ove 10 yea s of expe ience in the emoval of va ious contaminants f om envi onmental media.
I have co-autho ed seve al pee - eviewed pape s pe taining to the emoval of a senic f om
g oundwate utilizing i on o i on-tailo ed adso bents. I have also p eviously evaluated
emedies fo a senic contaminated g oundwate (including MNA) at coal ash disposal sites, as
well as the use of va ious technologies to t eat effluent impacted by metals and othe
constituents at a coal mining site. My CV is attached in Appendix A.
II. Scope of Work
I was etained by the Southe n Envi onmental Law Cente (SELC) to evaluate whethe
Monito ed Natu al Attenuation (MNA), in conjunction with Cap -in -Place, is an app op iate
emedy fo Duke's Buck Steam Station (Buck site) nea Salisbu y, NC.
III. Bas s of Op n on
My opinion is based on site specific documents, as well as scientific lite atu e, and my education
and expe ience. My opinion is based on a easonable deg ee of enginee ing and scientific
ce tainty. I ese ve the ight to supplement my opinions should additional info mation become
available.
IV. Methodology
My ole in this matte was to evaluate whethe MNA, in conjunction with Cap -in -Place, is an
app op iate emedy fo the Buck site. An evaluation of the app op iateness of MNA at a site
equi es an in-depth uncle standing of the p ocesses that constitute natu al attenuation at the
site and how the site specific envi onmental conditions impact these p ocesses. Fo the Buck
site, knowing the constituents of inte est (COls) and that the emedial st ategy p oposed by
Duke Ene gy was based on co -p ecipitation and adso ption, I evaluated whethe these p ocesses
we a occu ing uncle the specific conditions found at the Buck site. My evaluation utilized the
c ite is established by the U.S. EPA fo MNA of ino ganic contaminants in g oundwate ; the
same c ite is identified by Duke's consultants in thei analyses.
My opinions a e based on conside ation of data and info mation p ovided in the Comp ehensive
Site Assessment Repo t, the Co ective Action Plan Pa t 1, and the Co ective Action Plan Pa t 2
fo the Buck site; and on methods that I have used in othe scientific o enginee ing inqui ies
conce ning envi onmental p ocesses, which a e based upon methods and analysis widely
accepted in the published, pee - eviewed lite atu a in the fields of envi onmental science and
enginee ing. Fi st, I examine the data available to dete mine whethe a p ocess is wo king, and
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if not I then conduct esea ch to dete mine why. This esea ch gene ally involves a eview of
the elevant pee - eviewed lite atu e followed by an analysis of the applicability of the lite atu e
to the p ocess being evaluated.
In this matte I examined all of the available data fo the coal ash, the g oundwate , and the
solid-wate pai analyses to gain an uncle standing as to whethe COls we e natu ally
attenuating and to gain an uncle standing of the site conditions influencing natu al attenuation.
I then conducted a lite atu a sea ch fo studies on simila MNA applications. Since the
application of MNA as a t eatment fo COls in g oundwate at coal ash sites is new, published
lite atu a on sites whe e it has been implemented fo such pu pose is not yet available fo
assessment of MNA's pe fo mance in this capacity. The efo e, I eviewed a numbe of studies in
the pee - eviewed lite atu a that had examined the effectiveness of t eating coal ash leachate
o individual COls in othe systems with i on o manganese oxides in active o enginee ed
t eatment systems. These studies included my own publications investigating how i on and
a senic behave in g oundwate t eatment ope ations in o de to design effective t eatment
systems fo a senic emoval. Based on my knowledge, t aining, education, and yea s of
expe ience esea ching emoval by adso ption onto i on oxides, I knew that a numbe of facto s
can influence the adso ption of COls to metal oxides so I conducted an investigation to
dete mine whethe the Buck site conditions we a impacting MNA.
My ole also involved evaluating the effectiveness of MNA uncle Duke's p oposed plan of
capping the Buck site. The efo e, I conducted a simila analysis of MNA uncle alte ed site
conditions based on this p oposed scena io.
My analysis focused on a numbe of COls as identified in my opinion below in Section VI. Fo the
COls not discussed, I am not making a dete mination on whethe MNA is an app op iate
emedy.
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V. Background
A. Coal Ash and the Buck Site
• Coal ash is the waste mate ial p oduced f om the bu ning of coal in coal-fi ed powe
plants. It is comp ised of a numbe of byp oducts. Fo example, fly ash is "a ve y fine
powde y mate ial comp ised mostly of silica made f om the bu ning of finely g ound
coal in a boile ." (U.S. EPA 2016). Bottom ash, is aptly named fo the ash pa ticles
that a e too la ge to be ca ied into the smoke stacks and thus collect in the bottom
of the boile (U.S. EPA 2016). Both p oducts a e commonly efe ed to as coal ash.
• Coal ash in gene al is comp ised mainly of oxides of silica, aluminum, i on and
calcium, and also contains nume ous othe elements such as antimony, ch omium,
cobalt, and vanadium. Exposu a of coal ash to wate is known to cause the leaching
and elease of coal ash constituents to g oundwate and su face wate (Elect is
Powe Resea ch Institute 2009, Liu et al. 2004, Lokeshappa et al. 2014, Abe nethy et
al. 1969).
• The Buck Steam Station (Buck site) occupies an a ea of app oximately 640 ac es
along the southe n bank of the Yadkin Rive nea Salisbu y, No th Ca olina.
Beginning in 1926 and continuing th ough ea ly 2013, coal was bu ned at the site to
p oduce elect icity. (Co ective Action Plan Pa t 1).
• At the Buck site, coal ash was sluiced into an ash basin system beginning in 1957.
The ash basin system at the Buck site is comp ised of 3 cells, associated ea then
dikes, discha ge st uctu es, and two canals. The ash basin system discha ges to the
Yadkin Rive . The coal ash cells occupy a total a ea of app oximately 171 ac es and
contain app oximately 4.2 million cubic ya ds of coal ash. (Co ective Action Plan
Pa t 1, Comp ehensive Site Analysis Repo t). Acco ding to Duke's website, the "total
volume of ash" at the Buck site is 5.31 million tons (Duke Ene gy Ash Met ics).
• Coal ash disposal at the Buck site has led to a numbe of constituents in site
g oundwate that exceed applicable standa ds. Duke indicated that an examination
of the site data eveals that "concent ations of constituents of inte est (COls)
att ibutable to sou ce a eas at the Buck site a e p esent beneath and downg adient
of the ash basin and ash sto age a ea, and no th of the ash basin" (Co ective Action
Plan Pa t 1, Co ective Action Plan Pa t 2).
• Duke has indicated that the COls in g oundwate at the Buck site att ibutable to ash
handling include antimony, a senic, ba ium, bo on, ch omium, hexavalent
ch omium, cobalt, i on, manganese, nickel, pH, selenium, sulfate, thallium, total
dissolved solids (TDS), and vanadium. (Co ective Action Plan Pa t 2)
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• These g oundwate contaminants will t avel with the g oundwate unless they a e
emoved (adso bed, p ecipitated, etc.) along the g oundwate flow path. Acco ding
to the Co ective Action Plan Pa t 2 fo the Buck site, "COls t anspo t f om the
sou ce a eas is gene ally in a no the ly di ection towa d the Yadkin Rive and the
easte n and weste n unnamed t ibuta ies, which discha ge to the Yadkin Rive ".
• Duke has p oposed to utilize an enginee ed cap system as a sou ce cont of measu e
at the Buck site "which will minimize infilt ation th ough the cove ed a ea educing
possible impacts f om potentially impacted soil" (Co ective Action Plan Pa t 2).
Duke uncle stands that educing infilt ation will educe the echa ge of oxygen into
site g oundwate and likely c eate mo a anoxic (less oxygen) conditions, which can
thus impact the mobility of constituents in the g oundwate (Co ective Action Plan
Pa t 2, Appendix Q.
• Even with the placement of a cap ove the coal ash a eas, modeling pe fo med on
behalf of Duke p edicted that concent ations of antimony, cobalt, hexavalent
ch omium, and vanadium in the g oundwate would exceed applicable standa ds at
the compliance bounda y 100 yea s (o mo e) into the futu e (Co ective Action Plan
Pa t 2). The COls that a e p ojected to exceed applicable standa ds at the
compliance bounda y 100 yea s (o mo e) into the futu a based Duke's modeling
a e the focus of my analysis below.
• Acco ding to the Co ective Action Plan Pa t 2 fo the Buck site, "the g oundwate
model did not allow fo emoval of COI via co -p ecipitation with i on oxides, which
likely esulted in an ove p ediction of COI t anspo t". In esponse to this limitation
of the model, Duke submitted Appendix E and Appendix Hof the Co ective Action
Plan Pa t 2 to suppo t the use of MNA as a emedy in conjunction with cap -in-place
to educe the concent ations of the COls at the Buck site.
B. Monito ed Natu al Attenuation (MNA)
• MNA elies solely on natu al envi onmental geochemical p ocesses to mitigate
concent ations of contaminants (no active emediation) with egula ly scheduled
monito ing to assess whethe MNA is wo king. Acco ding to the USEPA (2012):
"Monito ing typically involves collecting soil and g oundwate samples to
analyze them" fo the contaminants of conce n and othe site pa amete s. The
" ight conditions must exist uncle g ound to clean sites p ope ly and quickly
enough."
• COls at the Buck site a e elements (ino ganics), and the efo a cannot be dest oyed.
Natu al p ocesses to immobilize ino ganics include adso ption, p ecipitation/co-
p ecipitation, and/o oxidation- eduction eactions (U.S. EPA 2007a). Duke p oposes
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to ely on these natu al p ocesses in its selection of MNA as a emedy fo the Buck
site (Co ective Action Plan Pa t 2, Mille 2011).
• Specifically, Duke is elying upon adso ption/co-p ecipitation of COls onto hyd ous
metal oxides, such as i on and manganese in its selection of MNA as a emedy
(Co ective Action Plan Pa t 2, Appendix E, and Appendix H). In educed fo ms (i on
and manganese in the +2 oxidation state), i on and manganese (also components of
coal ash) have highe solubility and mobility. As these species mig ate f om thei
sou ce and encounte mo a oxidized conditions, p ecipitation (pa ticula ly fo i on)
as insoluble species (i on in the +3 oxidation state and manganese in the +4
oxidation state) occu s c eating su faces onto which Cols can be adso bed. MNA
based on these p ocesses is successful only uncle the ight conditions, which will be
discussed in mo a detail below.
• In gene al, many g oundwate constituents a e known to adso b onto i on oxide
su faces. In gene al, adso ption of g oundwate constituents onto manganese oxide
su faces is not as well studied, though it is known that manganese oxide is not an
effective adso bent fo a senic, but has been epo ted to have high affinity fo
cobaltuncle the ight conditions (Hoffman et al. 2006, Salminen 2005).
• In gene al, the e a e a numbe of facto s that influence the effectiveness of natu al
attenuation fo ino ganics at a site. These facto s include (but a e not limited to)
the oxidation- eduction potential of the g oundwate , the pH, competition fo
adso ption sites, complexation, the elative ates of oxidation between a COI and a
potential adso bent such as i on, the amount of COI(s) in the coal ash sou ce, and
atios of COls to adso bents.
o The speciation of a COI is dependent upon pH and the oxidation- eduction
potential of the g oundwate . Potential emoval mechanisms fo a COI can
change depending upon the speciation of the COI.
o In addition to COls having to compete against each othe fo adso ption sites,
othe constituents p esent in the g oundwate can also significantly impact the
adso ption of COls onto hyd ous metal oxide su faces. Fo example, silica,
phosphate, bica bonate, and dissolved o ganic ca bon can p esent competition
p oblems (Meng et al. 2002, Meng et al. 2000, Holm et al. 2008, Su and Puls
2003, Holm 2002, Mille 2001, Swedlund and Webste 1999, Chen et al. 2007,
Sa ka et al. 2014, Ma iussen et al. 2015, U.S. EPA 2007b). Based on my eview
of site data, to my knowledge, concent ations of silica and phosphate in Buck
site g ound g oundwate have not been monito ed.
■ G oundwate typically contains silica in the ange of 3.3 to 21 mg/L (as Si)
(Holm et al. 2008, Davis et al. 2001). Silica is known to limit the adso ption
of COls onto i on oxides (Meng et al. 2000, Davis et al. 2001, Swedlund and
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Webste 1999). Dissolved silica at concent ations even below the typical
ange found in g oundwate has been shown to limit adso ption of the COls
(Mille 2001). Silica comp ises a majo f action of coal ash by weight
(Elect is Powe Resea ch Institute 2009), and has been found in the
g oundwate between 180 and 650 mg/L as Si at a coal ash site in the mid-
Atlantic egion.
■ Concent ations of phosphate below 1 mg/L have been shown to limit
adso ption of COls. The p esence of silica is known to magnify the impact of
phosphate. Phospho us pentaoxide (which fo ms phosphate in wate ) is a
known constituent of coal ash (Meng et al. 2002, Meng et al. 2000, Holm et
al. 2008, Su and Puls 2003, Holm 2002, Blackmo a et al. 1996, Liu et al.
2004).
■ With ega d to cobalt adso ption onto manganese oxide, othe metals such
as coppe , nickel, and zinc may outcompete it fo adso ption sites
(Mukhe jee et al. 2013). The p esence of bo ate (bo on is a site COI) can
also significantly educe the adso ption of cobalt onto manganese oxides
(Hasany and Qu eshi 1981).
o Othe constituents in g oundwate can fo m complexes with metals which can
dec ease COI adso ption/co-p ecipitation. Fo example, vanadium, a site COI,
can fo m complexes with sulfate (Salminen 2005, U.S. EPA 2007a).
o When utilizing i on to emove COls, such as a senic and vanadium, oxidation of
these ino ganics should occu simultaneously with the oxidation of i on to
achieve optimal emoval (Hoffman et al. 2006, Rocca o and Vagliasindi 2015).
• Due to the numbe of va iables that can impact MNA of ino ganics, the feasibility of
utilizing natu al attenuation fo ino ganics must be assessed on a site -by -site basis
because the effectiveness is highly site specific (Reisinge et al. 2005, Mille 2011).
• Acco ding to the U.S. EPA, dete mining the feasibility of using MNA at a site fo an
ino ganic constituent at a site is a fou -tie ed evaluation. These tie s, summa ized
f om U.S. EPA (2007a) a e as follows (Co ective Action Plan Pa t 2, Appendix H):
Tier I Source Control Is the contaminant mass in the plume decreasing?
Tier II Attenuation Mechanism Is the chemical mechanism well understood?
Tier III Attenuation Capacity Is the capacity and permanence of the mechanism
sufficient?
Tier IV Monitoring & Contingency How will monitoring be conducted? What actions will be
taken if monitoring indicates attenuation is lacking?
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• The envi onmental geochemical p ocesses that constitute natu al attenuation fo
COls at the Buck site a e ongoing, and have been ongoing since coal ash disposal
began; these p ocesses do not begin at the time MNA is app oved as a emedy fo a
site. The efo e, a Tie I evaluation establishes whethe natu al attenuation is
cu ently occu ing at the site, and if so is the fi st step in demonst ating the long
to m app op iateness of MNA as a site emedy. Appendix H of the Co ective Action
Plan Pa t 2, titled "Monito ed Natu al Attenuation Technical Memo andum"
included a Tie I and Tie II evaluation fo the Buck site and is Duke's actual
evaluation of MNA at the Buck site. The esults of this appendix a e then
summa ized in the body of the Co ective Action Plan Pa t 2 epo t.
• In the Tie I evaluation p ocess, concent ations of COls we a measu ed in Buck site
wate and soil (solid) f om the same location and depth. If attenuation is occu ing
via adso ption onto aquife solids, the concent ation of the COI on the solid mate ial
should inc ease with the concent ation of the COI in the g oundwate . An example
of this type of analysis is shown below in Figu e 1 (U.S. EPA 2007a). Acco ding to
the Monito ed Natu al Attenuation Memo andum fo the Buck site, "[a] st ong
positive co elation between COI concent ation in wate and solid pai s indicates
attenuation and is the fi st step (Tie 1) in evaluation of MNA as a emedial
technology" (Co ective Action Plan Pa t 2, Appendix H). Conve sely, acco ding to
the U.S. EPA, sites whe e COI attenuation is not obse ved "would be eliminated
f om fu the conside ation of MNA as pa t of the cleanup emedy" (U.S. EPA 2007a).
F gure 1. Example of a sol d -water pa r analys s to
demonstrate attenuat on (adapted from U.S. EPA 2007a)
Site -Specific
Sorption Trend
(A'
Attenuation
-
�B)
No Attenuation
Aquaws Concerurattin (ppm}
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• Simila to the elationship analysis shown in Figu a 1, a p opo tionality constant (Kd)
can be dete mined in the labo ato y by allowing site soil samples to equilib ate with
wate . Kd is defined as the concent ation of the COI in the solid divided by the
concent ation of the COI dissolved in the wate . Kd values can give an indication of
the potential fo dissolved COls in g oundwate to adso b onto soil, which then can
be elated to the ate at which a COI moves in elation to the ate of g oundwate
movement (Co ective Action Plan Pa t 2, Appendix H).
• As stated above, capping the ash basins is intended to educe infilt ation th ough
the coal ash and into the g oundwate . Acco ding to Duke's consultants, cap -in-
place would educe the oxygen in the subsu face, "p esumably c eating a mo e
anoxic envi onment" (Co ective Action Plan Pa t 2, Appendix Q. Schwa tz et al.
(2016) have also stated that capping a site will lead to mo a anoxic conditions in the
site g oundwate . The speciation of constituents in the g oundwate va ies with pH
and the edox state. Appendix E of the Co ection Action Plan Pa t 2 contained the
esults of geochemical modeling conducted to evaluate "the adso ption of COls
uncle a wide ange of dissolved oxygen, as well as pH, oxidation- eduction
potential, and TDS." The U.S. EPA ecommended that modeling esults be "used as
seconda y lines of evidence in suppo t of site-specific measu ements that
demonst ate active so ption of the contaminant onto aquife solids" and cannot be
elied upon independently (U.S. EPA 2007a)
VI. Op n on: Mon tored Natural Attenuat on s not an appropr ate remedy for
const tuents of nterestl (COls) at the Buck s te.
A. When MNA is based upon adso ption of Cols onto p ecipitated i on and manganese oxides, the
utilization of MNA in combination with capping is p oblematic as conditions fo MNA a e less
favo able following capping.
• The placement of a cap at the Buck site will lead to mo a anoxic (lowe oxidation -
eduction potential) in site g oundwate . The solubility of i on and manganese is
st ongly influenced by oxidation- eduction potential conditions, with solubility
inc easing as the oxidation- eduction potential is dec eased. Both a e eadily
mobilized o esolubilized uncle anoxic conditions. COls that had p eviously
adso bed to i on o manganese will be emobilized and potentially lead to a slug of
COls ente ing the g oundwate . When i on and manganese a e in the dissolved
phase, COls cannot adso b to them. (Salminen 2005, Masscheleyn et al. 1991, Ha to
et al. 2012, Schwa tz et al. 2016, U.S. EPA 2007b, Ta utis and Unz 1995).
1 Constituents of inte est, as used he e, efe to the constituents that a e p ojected by Duke via modeling to
exceed applicable standa ds 100 yea s (o mo e) in the futu e. These constituents a e antimony, cobalt,
hexavalent ch omium, and vanadium.
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• Though i on is eadily oxidized when it comes into contact with oxygen, ae ation
(oxygen) is not effective fo oxidizing dissolved manganese (manganese in the +2
oxidation state) to the elatively insoluble +4 oxidation state. The efo e d inking
wate t eatment plants utilize a st ong oxidant such as ozone, chlo ine dioxide, o
potassium pe manganate when manganese emoval is equi ed. Additionally, the
p esence of dissolved i on in the g oundwate inhibits the fo mation of manganese
oxides. Only 14% manganese emoval was obse ved in a settling basin following
ae ation used to t eat coal ash leachate at a site in Pennsylvania (Hoffman et al.
2006, Ta utis and Unz 1995, Robinson -Lo a and B ennan 2011, Rightnou and
Hoove 1998). This is impo tant because the fo mation of manganese oxides has
been identified as a component of the MNA site emedy in addition to i on oxides.
• Infilt ation (and thus oxygen echa ge) would be educed ove the a ea of the Buck
site uncle the cap, and thus i on and manganese mobility will be enhanced (less
i on and manganese oxide p ecipitation/COI adso ption occu ing within the a ea
that is capped). This inhe ently sho tens the distance to the compliance bounda y
ove which these MNA p ocesses can potentially occu
• Conce n ove a eduction in site g oundwate oxidation- eduction potential and
enhancement of a senic solubility as a esult of closu a plans fo coal ash
impoundments that include capping, led a g oup of scientists to ecently state that
"even if no p evious g oundwate contamination issues have been epo ted,
capping methods that might induce anae obic conditions should be avoided in the
closu a of unlined impoundments" (Schwa tz et al. 2016).
B. Kd values dete mined in the labo ato v cannot be eliably utilized as a means to demonst ate
site-specific attenuation at the Buck site.
• As stated above, Kd is a pa amete to estimate the potential fo the adso ption of
the COls in the g oundwate onto soil. Fo the Buck site, Kd values we a dete mined
expe imentally in the labo ato y using "synthetic g oundwate ", which was ve y
limited in to ms of the numbe of constituents and in many cases the concent ation
of these constituents, and the efo a was not ep esentative of g oundwate
impacted by coal ash at the Buck site. Fo example, the "synthetic g oundwate " did
not include a numbe of competing constituents that a e known to impact COI
so ption. These include silica and phosphate, which can significantly impact COI
adso ption. Silica, in pa ticula , can be p esent at ve y high concent ations at coal
ash disposal sites.
• The efo e, the Kd values dete mined in the labo ato y we e likely biased high
because the "synthetic g oundwate " did not have othe constituents competing fo
the same adso ption sites.
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• Duke stated that "typically Kd expe iments a e also conducted uncle oxic [high
oxygen] conditions, which may not eflect actual site conditions. Consequently, Kd
values f om labo ato y expe iments should be inte p eted and used with caution
because they may not account fo the full ange of so ption conditions that occu in
hete ogeneous, natu al soils." (Co ective Action Plan Pa t 2 Appendix E)
C. MNA should have not been selected as a potential site emedy fo antimony, ch omium,
hexavalent ch omium and cobalt.
Based on the Tie I evaluation fo a numbe of Buck site COls, Duke's consultants stated that
attenuation "was not obse ved" and that the espective COls "we e not ca ied th ough to Tie
11" analysis (Co ective Action Plan Pa t 2, Appendix H). Instead of eliminating MNA as a
potential site emedy as U.S. EPA states (EPA 2007a), MNA was selected by Duke to supplement
capping -in-place (Co ective Action Plan Pa t 2). The COls this applies to a e discussed below:
1. Antimony
• An analysis of antimony was not p esented in Appendix H, but the body of the
Co ective Action Plan Pa t 2, stated that antimony "attenuation using solid-wate
pai s was not obse ved" and that antimony was "not ca ied th ough to Tie II". In
addition, esults of geochemical modeling "indicate ve y low adso ption" fo
antimony (Co ective Action Plan Pa t 2, Appendix Q.
2. Ch omium and hexavalent ch omium
• The Monito ed Natu al Attenuation Technical Memo andum (Appendix H of the
Co ective Action Plan Pa t 2) did not distinguish between hexavalent ch omium
(ch omium in the mo e toxic +6 oxidation state) o ch omium (total ch omium). As
stated above, attenuation of ch omium was not obse ved at the Buck site.
• The t end line fo the solid-wate pai analysis p esented in Appendix H of the
Co ective Action Plan Pa t 2 demonst ated a negative co elation between the
concent ation of ch omium in the dissolved phase in compa ison to the
concent ation on the solid phase, thus "attenuation is not obse ved in this plot" and
"ch omium should not be ca ied th ough to Tie II analysis". The Co ective Action
Plan Pa t 2 ( epo t itself) also stated that ch omium "attenuation using solid-wate
pai s was not obse ved" and that ch omium was "not ca ied th ough to Tie II".
• Capping of the site will lead to mo a anoxic conditions in the site g oundwate
(Schwa tz et al. 2016, Co ective Action Plan Pa t 2, Appendix E), which could lead to
hexavalent ch omium (if p esent) conve ting to a less oxidized ch omium species.
• At pH values above 2 and in the p esence of oxygen, ch omium in the +3 oxidation
state is subject to oxidation to ch omium in the +6 oxidation state (U.S. EPA 2007b).
If hexavalent ch omium still emained following capping, o fo med f om C +3
10

mig ating to a eas of highe oxygen, MNA would not be an app op iate emedy as
hexavalent ch omium "is highly mobile as an aqueous complexed species and, in
situations whe a oxygen bea ing echa ge have been identified, has been known to
pe sist above acceptable limits in widesp ead a eas f om point sou ces in nume ous
studies." (Co ective Action Plan Pa t 2, Appendix E). Ch omium in the +6 oxidation
state [C (VI)] is typically not so bed as well as many othe g oundwate constituents
and is often outcompeted fo adso ption sites. The p esence of sulfate, a weakly
adso bing species, can also cause significant eductions in the amount of C (VI)
adso bed onto hyd ous metal oxides, and sulfate was measu ed at concent ations
as high as 703 mg/L in Buck site g oundwate in 2015 (U.S. EPA 2007b, Co ective
Action Plan Pa t 2).
3. Cobalt
• An analysis of cobalt was not p esented in Appendix H, but the body of the
Co ective Action Plan Pa t 2, stated that cobalt "attenuation using solid-wate pai s
was not obse ved" and that cobalt was "not ca ied th ough to Tie II".
D. MNA is not app op iate at the Buck site fo vanadium
• An analysis of solid-wate pai s fo vanadium was not pe fo med in Appendix H of
the Co ective Action Plan Pa t 2, but the data fo such an analysis was found in
Table 3 of this same appendix. Vanadium concent ations on the solid phase a e
plotted against co esponding dissolved vanadium concent ations in the wate
phase in Figu e 2 shown below.
F gure 2. Sol d -water pa r analys s for Vanad um (data from Append x H of the Correct ve Act on
Plan Part 2).
140
120
ao
100
ao
80
E
= 60
a
c�
40
c
0
0 5 10 15 20
Vanadium, dissolved (ug/L)
11

• The t end line fo this solid-wate pai s analysis fo vanadium clea ly has a
dec easing slope, thus attenuation of vanadium is not obse ved at the Buck site, and
the efo e vanadium does not pass Tie I of the fou -tie ed MNA feasibility
evaluation fo the Buck site. As a eminde , Duke ecognizes that "a st ong positive
co elation between COI concent ation in wate and solid pai s indicates
attenuation and is the fi st step (Tie 1) in evaluation of MNA as a emedial
technology." (Co ective Action Plan Pa t 2, Appendix H).
• In gene al, vanadium in the +3 oxidation state [V(111)] is less soluble than vanadium
in the +5 oxidation state (Salminen 2005). Attenuation of vanadium is not obse ved
at the Buck site despite that uncle cu ent conditions at the Buck site, vanadium "is
expected to p edominantly exist as V(111)" (Co ective Action Plan Pa t 2, Appendix
E).
12

VII. References
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Blackmo e, DPT; J Ellis and PJ Riley (1996). T eatment of a vanadium -containing effluent by
adso ption/cop ecipitation with i on oxyhyd oxide. Wate Resea ch 30(10): 2512-6.
Chen, W; R Pa ette, J Zou, FS Cannon and BA Dempsey (2007). A senic emoval by i on modified
activated ca bon. Wate Resea ch 41: 1851-8.
Comp ehensive Site Assessment Repo t. Buck Steam Station. Fo Duke Ene gy Ca olinas, p epa ed
by HDR Enginee ing Inc. August 23, 2015.
Co ective Action Plan Pa t 2. Buck Steam Station Ash Basin. Fo Duke Ene gy Ca olinas, p epa ed by
HDR Enginee ing Inc. Feb ua y 19, 2016.
Co ective Action Plan Pa t 1. Buck Steam Station Ash Basin. Fo Duke Ene gy Ca olinas, p epa ed by
HDR Enginee ing Inc. Novembe 20, 2015.
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hyd oxide: mobilization of i on colloids and inte fe ence with so ption of a senate and humic
substances. Envi onmental Science & Technology 35: 3158-62.
Duke Ene gy (2015). Duke Ene gy Ash Met ics. https://www.duke-ene gy.com/pdfs/duke-ene gy-
ash-met ics.pdf
Elect is Powe Resea ch Institute (2009). Coal Ash: Cha acte istics, Management, and Envi onmental
Issues. www.whitehouse.gov/sites/default/files/omb/assets/oi a_2050/2050_meeting_101609-
2.pdf
Ha te, PT; JD Ayotte, A Hoffman, KM Revesz, S Lamb and JK Bohlke (2012). Hete ogeneous edox
conditions, a senic mobility, and g oundwate flow in a f actu ed- ock aquife nea a waste
eposito y site in New Hampshi e, USA. Hyd ogeology Jou nal 20(6): 1189-1201.
Hasany, QM and MA Qu eshi (1981). Adso ption studies of cobalt (II) on manganese dioxide f om
aqueous solutions. Inte national Jou nal of Applied Radiation and Isotopes 32: 747-52.
Hoffman, GL; DA Lytle, TJ So g, ASC Chen and L Wang (2006). Design Manual: Removal of A senic
f om D inking Wate Supplies by I on Removal P ocess. Ap it 2006. EPA/600/R-06/030.
Holm, TR; WR Kelly, SD Wilson and JL Talbott (2008). A senic emoval at Illinois i on emoval plants.
Jou nal AWWA 100(9): 139-150.
13

Holm, TR (2002). Effects of C032-/bica bonate, Si, and PO43-on a senic so ption to HFO. Jou nal
AWWA 94(4):174-81.
Liu, G; H Zhang, L Gao, L Zheng and Z Peng (2004). Pet ological and mine alogical cha acte izations
and chemical compositions of coal ashes f om powe plants in Yanzhou mining dist ict, China. Fuel
P ocessing Technology 85: 1635-46.
Lokeshappa, B; AK Dikshit, Y Luo, TJ Hutchinson and DE Giamma (2014). Assessing bioaccessible
f actions of a senic, ch omium, lead, selenium, and zinc in coal fly ashes. Inte national Jou nal of
Envi onmental Science and Technology 11: 1601-10.
Ma iussen, E: IV Johnsen and AE St omseng (2015). Selective adso ption of lead, coppe , and
antimony in unoff wate f om a small a ms shooting nage with a combination of cha coal and i on
hyd oxide. Jou nal of Envi onmental Management 150: 281-7.
Masscheleyn, PH; RD Delaune and WH Pat ick J . (1991). A senic and selenium chemist y as affected
by sediment edox potential and pH. Jou nal of Envi onmental Quality 20: 522-7.
Meng, X; GP Ko fiatis, S Bang and KW Bang (2002). Combined effects of anions on a senic emoval
by i on hyd oxides. Toxicology Lette s 133: 103-11.
Meng, X; S Bang and GP Ko fiatis (2000). Effects of silicate, sulfate, and ca bonate on a senic
emoval by fe is chlo ide. Wate Resea ch 34(4): 1255-61.
Mille , GP (2011). Monito ed natu al attenuation: a emediation st ategy fo g oundwate impacted
by coal combustion p oduct leachate. 2011 Wo Id of Coal Ash Confe ence. May 9-12, 2011. Denve ,
CO.
Mille , GP (2001). Su face complexation modeling of a senic in natu al wate and sediment systems.
Ph.D. disse tation, New Mexico Institute of Mining and Technology.
Mukhe jee, J; J Ramkuma , S Chand amoukeeswa an, R Shukla and AK Tyagi (2013). So ption
cha acte istics of nano manganese oxide: efficient so bent fo emoval of metal ions f om aqueous
st earns. Jou nal of Radioanalytical and Nuclea Chemist y 297: 49-57.
Rightnou , TA and KL Hoove (1998). The Sp ingdale P oject: Applying Const ucted Wetland
T eatment to Coal Combustion By -P oduct Leachate. EPRI epo t TR -111473.
Robinson -Lo a, MA and RA B ennan (2011). Anae obic p ecipitation of manganese and co -existing
metals in mine impacted wate t eated with c ab shell -associated mine als. Applied Geochemist y
26: 853-62.
14

Rocca o, P and FGA Vagliasindi (2015). Cop ecipitation of vanadium with i on(III) in d inking wate : a
pilot -scale study. Desalination and Wate T eatment 55: 799-809.
Salminen, R (2005). Geochemical Atlas of Eu ope, Pa t 1— Backg ound Info mation, Methodology,
and Maps. weppi.gtk.fi/publ/fo egsatlas/text.
Sa ka , D; DK De, R Das and B Mandal (2014). Removal of o ganic matte and oxides of i on and
manganese f om soil influences bo on adso ption in soil. Geode ma 214-5: 213-6.
Schwa tz, GE; N Rive a, SW Lee, JM Ha ington, JC Howe , KE Levine, A Vengosh and H Hsu -Kim
(2016). Leaching potential and edox t ansfo mations of a senic and selenium in sediment
mic ocosms with fly ash. Applied Geochemist y 67: 177-85.
Swedlund, PJ and JG Webste (1999). Adso ption and polyme ization of silicic acid on fe ihyd ide,
and its effect on a senic adso ption. Wate Resea ch 33(16): 3413-22.
Ta utis, WJ and RF Unz (1995). 1 on and manganese elease in coal mine d ainage wetland
mic ocosms. Wate Science & Technology 32(3): 187-92.
U.S. EPA (2007a). Monito ed Natu al Attenuation of Ino ganic Contaminants in G ound Wate ,
Volume 1, Technical Basis of Assessment. EPA/600/R-03/139.
U.S. EPA (2007b). Monito ed Natu al Attenuation of Ino ganic Contaminants in G ound Wate ,
Volume 2, Assessment fo Non -Radionuclides Including A senic, Cadmium, Ch omium, Coppe , Lead,
Nickel, Nit ate, Pe chlo ate, and Selenium. EPA/600/R-03/140.
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basics#02
15

APPENDIX A
D . Robe t Pa ette CV
16

ROBERT PARETTE
Matson & Assoc ates, Inc.
331 East Foster Avenue, State College, PA 16801
Phone: [phone] Ema I: bparette@matson-assoc ates.com
EDUCATIO
Doctor of Philosophy August 2005
Env ronmental Eng neer ng
The Pennsylvan a State Un vers ty, Un vers ty Park, PA
D ssertat on: The Removal of Perchlorate from Groundwater v a Quaternary
Ammon um Cat on c Surfactant Pre -Loaded GAC
Master of Science May 2004
Env ronmental Eng neer ng
The Pennsylvan a State Un vers ty, Un vers ty Park, PA
Thes s: GAC Ta lored w th Organ c Cat ons for the Removal of Perchlorate from
Groundwater and Base/Ac d Chem cal Regenerat on of the GAC
Bachelor of Science February 1999
Chem cal Eng neer ng
Worcester Polytechn c Inst tute, Worcester, MA
WORK EXPERIE CE
Matson and Associates, Inc., State College, PA
Env ronmental Eng neer (P.E.)/Env ronmental Chem st (2009-2014)
V ce Pres dent of Eng neer ng/Project Manager for Matson B ofuels (2009-2011)
The Pennsylvania State University, Dept. of Civil and Environmental Engineering
Post -Doctoral Research Assoc ate (2005-2009)
Graduate Research Ass stant (2000-2005)
Environmental Consultant
Ass stant to Penn State professor sery ng as an expert w tness (2007)
Hercules Incorporated Research Center, Wilmington, DE
Research Ass stant (1998)
REPRESE TATIVE PROJECT EXPERIE CE
• Rev ewed closure plan alternat ves for a coal ash mpoundment located n Conway, South
Carol na. Prepared wr tten comments address ng the lack of groundwater treatment (as part of
these closure plan alternat ves) and the feas b I ty of remed at ng the arsen c contam nated
groundwater.
A-1

• Evaluated the d sposal pract ces of waste salt conta n ng arsen c at a fac I ty along the
Menom nee R ver n W scons n n relat on to waste d sposal standards and the alternat ve
d sposal opt ons ava fable. Invest gated the spec at on of arsen c n the waste salts, the
propert es of the var ous arsen c spec es, and the transformat ons these arsen c spec es would
undergo n the env ronment.
• At Penn State, 9% years of R&D on technolog es to remed ate ground water. Th s R&D resulted
n numerous publ cat ons (I sted below) on the removal of arsen c and perchlorate from water.
Des gned and produced custom adsorbents for the removal of arsen c from groundwater.
Des gned and fabr cated a p lot plant w th a capac ty n excess of one m II on gallons per year to
study the removal of arsen c by a comb nat on of act vated carbon and ron from a var ety of
d fferent sources. Respons ble for develop ng exper mental and sampl ng plans for a number of
p lot and laboratory stud es.
• Evaluated treatment technolog es, and the feas b I ty of employ ng such technolog es, n
connect on w th remed at ng a large lake contam nated w th selen um. Prepared a report to be
ut I zed for publ c comments and negot at ons w th the power company.
• Evaluated the potent al mplementat on of var ous technolog es for a number of outfalls at a
coal m n ng operat on n western Pennsylvan a. Prepared wr tten comments address ng
shortcom ngs of a consent decree perta n ng to the s te.
• Evaluated wastewater treatment pract ces of a paper m II along the Fox R ver n W scons n n
relat on to the treatment opt ons ava fable (chronolog cally) to the pulp and paper ndustry and
the removal eff c enc es ach eved by var ous treatment technolog es across the ndustry.
• Des gned and conducted laboratory exper ments to test the mpact of MTBE on the removal of
other organ c contam nants from groundwater for a case nvolv ng MTBE n Suffolk County, NY.
Ut I zed mult ple f eld data sets to assess the ab I ty of act vated carbon to remove MTBE,
ass sted n the preparat on of expert w tness reports, and performed an extens ve I terature
rev ew pert nent to the case.
• Correlated s to act v t es at an abandoned chem cal manufactur ng plant n NJ w th
contam nants found n the near offshore areas of the s te; determ ned the or g n and chem cal
react ons beh nd the presence of 2,4,6,8-tetrachlorod benzoth ophene (2,4,6,8-TCDT), a
contam nant whose source was prev ously unknown.
• Evaluated the s ngle phase eff c ency for the str pp ng of CO2 n a cool ng tower model for an
nternat onal company that spec al zes n gases. Mod f ed the model's source code to reflect the
determ ned s ngle stage eff c ency, evaluated the I qu d to gas rat o ut I zed by the model, and
compared results from the model aga nst the exper mental data.
• Invest gated groundwater qual ty and consulted w th a forester at a res dent al s to n Centre
County, PA, mpacted by a nearby hous ng development.
• D rected the R&D efforts for Matson B ofuels from 2009 through 2011. Respons ble for the
management of three b od esel projects, w th grant fund ng n excess of $250K. Developed sol d
A-2

catalysts capable of convert ng low qual ty o I feedstocks to b od esel w th no feedstock
pretreatment and no soap format on. Des gned a p lot plant, w th a capac ty to produce more
than 1 m II on gallons of b od esel annually.
PUBLICATIO 5
R Parette, R McCr ndle, KS McMahon, M Pena-Abaurrea, E Re ner, B Ch tt m, N R ddell, G Voss, FL
Dorman, WN Pearson and M Robson (2016). Response to the comment on "Halogenated nd go dyes
I kely source of 1,3,6,8-tetrabromocarbazole and some other halogenated carbazoles n the
env ronment". Chemosphere 150: 414-5.
N R ddell, UH J n, S Safe, Y Cheng, B Ch tt m, A Konstant nov, R Parette, M Pena-Abaurrea, EJ Re ner, D
Po r er, T Stefanac, AJ McAlees and R McCr ndle (2015). Character zat on and b olog cal potency of
mono- to tetra -halogenated carbazoles. Env ronmental Sc ence & Technology 49 (17): 10658-66.
R Parette, R McCr ndle, KS McMahon, M Pena-Abaurrea, E Re ner, B Ch tt m, N R ddell, G Voss, FL
Dorman and WN Pearson (2015). Halogenated nd go dyes: a I kely source of 1,3,6,8-
tetrabromocarbazole and some other halogenated carbazoles n the env ronment. Chemosphere 127:
18-26.
R Parette and WN Pearson (2014). 2,4,6,8-Tetrachlorod benzoth ophene n the Newark Bay Estuary: the
I kely source and react on pathways. Chemosphere 111: 157-63.
W Chen, R Parette and FS Cannon (2012). P lot -scale stud es of arsen c removal w th granular act vated
carbon and zero -valent ron. Env ronmental Eng neer ng Sc ence 29(9): 897-901.
K Gombotz, R Parette, G Aust c, D Kannan and J Matson (2012). MnO and T O sol d catalysts w th low-
grade feedstocks for b od esel product on. Fuel 92(1): 9-15.
MK Sel em, S Komarnen, R Parette, H Katsuk, FS Cannon, MG Shah en, AA Khal I and IM Abdel -Ga d
(2011). Perchlorate uptake by organos I cas, organo -clay m nerals and compos tes of r ce husk w th
MCM-48. Appl ed Clay Sc ence 53: 621-6.
JP Patterson, R Parette and FS Cannon (2011). Compet t on of an ons w th perchlorate for exchange s tes
on cat on c surfactant-ta lored GAC. Env ronmental Eng neer ng Sc ence 28(4): 249-56.
JY K m, S Komarnen , R Parette and FS Cannon (2011). Perchlorate uptake by synthet c layered double
hydrox des and organoclays. Appl ed Clay Sc ence 51(1-2): 158-64.
JP Patterson, R Parette and FS Cannon (2010). Ox dat on of ntermed ate sulfur spec es (th osulfate) by
free chlor ne to ncrease the bed I fe of to lored GAC to remove perchlorate. Env ronmental Eng neer ng
Sc ence 27(10): 835-43.
MK Sel em, S Komarnen, R Parette, H Katsuk, FS Cannon, MG Shah en, AA Khal I and IM Abdel -Ga d
(2010). Compos tes of MCM-41 s I ca w th r ce husk: Hydrothermal Synthes s, character zat on and
appl cat on for perchlorate separat on. Mater als Research Innovat ons 14(5): 351-4.
A-3

S Komarnen , J Y K m, R Parette and FS Cannon (2010). As -Synthes zed MCM-41 s I ca: New adsorbent for
perchlorate. Journal of Porous Mater als 17: 651-6.
MJ Jang, FS Cannon, R Parette, S Yoon and W Chen (2009). Comb ned hydrous ferr c ox de and
quaternary ammon um surfactant to for ng of granular act vated carbon for concurrent arsen c and
perchlorate removal. Water Research 43(12): 3133-43.
W Chen, R Parette and FS Cannon FS (2008). Arsen c adsorpt on v a ron preloaded act vated carbon and
zero -valent ron. Journal of Amer can Water Works Assoc at on 100(8): 96-105.
W Chen, R Parette, J Zou, FS Cannon and BA Dempsey (2007). Arsen c removal by ron-mod f ed
act vated carbon. Water Research 41(9): 1851-8.
R Parette and FS Cannon (2006). Perchlorate removal by mod f ed act vated carbon. In Perchlorate
Env ronmental Occurrence, Chem stry, Tox cology, and Remed at on Technolog es. Spr nger Publ sh ng
Company, New York.
R Parette and FS Cannon (2005). The removal of perchlorate from groundwater by act vated carbon
to lored w th cat on c surfactants. Water Research 39(16): 4020-28.
R Parette, FS Cannon and K Weeks (2005). Remov ng low ppb level perchlorate, RDX, and HMX from
groundwater w th cetyltr methylammon um chlor de (CTAC) pre -loaded act vated carbon. Water
Research 39(19): 4683-92.
A-4