v>EPA
                                  United States
                                  Environmental Protection
                                  Agency
                                 Industrial Environmental Researc
                                 Laboratory
                                 Research Triangle Park NC 27711
                                  Research and Development
                                 EPA-600/S7-81-031  July 1981
Project Summary
                                  Facilities Evaluation  of
                                  High  Efficiency  Boiler
                                  Destruction  PCB  Waste
                                  J. E. Cotter and R. J. Johnson
                                   A   rendering  plant  by-product,
                                  yellow grease, was  found  to  be
                                  contaminated by PCB's from a trans-
                                  former leak. The PCB content (under
                                  500 ppm) determines the method of
                                  disposal under 40 CFR Part 761. For
                                  this evaluation, destruction in a high-
                                  efficiency boiler was evaluated as an
                                  alternative to  landfill  disposal. The
                                  process steam boiler belonging to the
                                  waste  owner, Seattle  Rendering
                                  Works, was evaluated as a candidate
                                  site for waste destruction. The logis-
                                  tics and fuel handling  requirements
                                  were found to be feasible to set up in a
                                  short time,  and the boiler size and
                                  residence time were determined to be
                                  likely to allow high destruction effi-
                                  ciency. With 99.9% destruction of
                                  PCB's, the downwind concentration
                                  was estimated by diffusion modeling
                                  to  be less than  OSHA limits for
                                  industrial exposure. Fuel characteris-
                                  tics of the yellow grease were used to
                                  support the  recommendation for
                                  100% grease fired as fuel.
                                   A  second high-efficiency  boiler
                                  candidate was also evaluated. The
                                  Shuffleton power plant, operated by
                                  Puget Sound Power & Light Company,
                                  operates three boilers from a common
                                  oil fuel supply system. The size and
                                  facilities at this site were determined
                                  to satisfy all the prerequisites for high-
                                  efficiency boilers (40 CFR Part 761),
                                  and to best be operated by blending
                                  the waste  with the normal fuel oil
                                  supply. A 30% waste blend was
                                  evaluated and found to be completely
                                  miscible and feasible with respect to
                                  logistical support.
                                   A verification test burn was recom-
                                  mended and outlined for either candi-
                                  date site. Current  EPA protocol and
                                  policy developments for PCB destruc-
                                  tion were found to be appropriate for
                                  the preparation of a candidate facility
                                  test  plan  and  an example public
                                  notice.
                                   This report is submitted in fulfill-
                                  ment of Contract  No. 68-02-3174,
                                  Work Assignment  No. 11, by TRW
                                  Environmental Engineering Division,
                                  under sponsorship of the U.S. Envi-
                                  ronmental  Protection  Agency. This
                                  report covers the period January 10,
                                  1980 to April 1,1980, and work was
                                  completed as of July 1, 1980.
                                   This Project Summary was develop-
                                  ed by EPA's Industrial Environmental
                                  Research Laboratory.  Research Tri-
                                  angle Park. NC. to announce key find-
                                  ings of the research project that is fully
                                  documented in a separate report of the
                                  same title (see Project Report ordering
                                  information at back).


                                  Introduction

                                  Source of Contaminated
                                  Waste
                                   A quantity of tallow (yellow grease),
                                  produced from the rendering of chicken
                                  packing by-products, was contaminated
                                  by a transformer leak at a packing plant
                                  in Billings, MT. The incident occurred in
                                  1979, and by mid-1979 the contamina-

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ted yellow grease had already been sold
to distributors who had combined the
contaminated  material   with   other
stocks. Routine FDA inspections identi-
fied the PCB contamination, and subse-
quent analyses of blended stocks were
carried out. The FDA notified the EPA
Region X headquarters in September
1979 of the results of those analyses
where the PCB  content was greater
than 50 ppm, and therefore subject to
EPA jurisdiction.
  All  grease  stocks containing  more
than 50 ppm of PCB were traced to two
tanks at 290011 th Avenue SW, Seattle,
WA. The tanks contain (as of the date of
this report) approximately 500,000 Ibs
and  600,000 Ibs, or about  150,000
gallons total.  FDA inspection of the
grease revealed  PCB  concentrations
ranging from 116 to 391 ppm, based on
four samples taken from the tanks, and
duplicate assays.
Disposal Options
  The contaminated grease, having a
PCB content of under 500 ppm, does not
require destruction in an EPA-approved
incinerator. The final ruling governing
PCB disposal, 40 CFR Part 761, identi-
fies  destruction  in  high-efficiency
boilers or disposal in chemical  landfills
as acceptable alternatives.
  "High-efficiency" boilers are defined
to include power generation boilers and
industrial boilers that operate at a high
combustion   efficiency  (99.9%)  as
def i ned by the percentage ratio of CO 2to
CO+COz concentrations in the combus-
tion gases. These boilers are assumed
to be capable of achieving 99.9% or
greater PCB destruction efficiency.
  There are two  approved locations in
EPA Region X where PCB contaminated
waste may be disposed. These chemical
landfills are  Chem-Nuclear  Systems
(Arlington,  OR) and Wes-Con (Grand
View, ID). It was estimated by Region X
that landfilling would cost a waste
owner around 80/lb.
Prerequisites for High-
Efficiency Boiler Destruction

  The Regional  Administrator may
grant approval for PCB thermal destruc-
tion in a boiler if a number of prerequi-
sites are met:
 1.  The boileris rated at a minimum of
     50 million Btu/hour.

 2.  The  PCB  contaminated waste
     comprises no more than 10% of
     the total volume of fuel.

 3.  The waste will not be added to the
     combustion  chamber   during
     boiler  start-up   or  shut-down
     operations.

 4.  The combustion  emissions will
     contain at least 3% excess oxygen
     and  the  carbon  monoxide
     concentration will be less than 50
     ppm for oil- or gas-fired boilers or
     100 ppm for coal-fired boilers.

 5.  The combustion process will  be
     monitored continuously or at least
     once each hour that the PCB con-
     taminated  wastes  are  being
     burned to determine the  percent-
     age of excess  oxygen  and  the
     carbon monoxide level in the com-
     bustion emissions.

 6.  The primary fuel and waste feed
     rates are monitored at least every
     15 minutes whenever burning the
     waste.

 7.  The carbon monoxide and excess
     oxygen levels are monitored at
     least  once an hour, and if they fall
     below the levels  specified,  the
     flow  of  wastes  to the  boiler is
     stopped  immediately.

 8.  Records  are  maintained  that
     include the monitoring data in (5)
     and (6), above, and the quantities
     of  PCB-contaminated  waste
     burned each month. When burn-
     ing PCB wastes, the boiler must
     operate at a level of output no less
     than  the output at which  the
     reported carbon  monoxide and
     excess  oxygen   measurements
     were taken.
Candidate Sites for Waste
Destruction
  Two  boiler/incinerator sites were
selected for study  in this report: the
steam boiler at the Seattle Rendering
Works plant in  Seattle,  WA, and the
utility boilers at Puget Sound Power &
Light's Shuffleton Plant in Renton, WA.
Seattle Rendering Works
Analysis

Facility Operations
Background
  The Seattle  Rendering Works,  Inc.,
facility is  located at 5795 S. 130th
Place,  Seattle,  WA,  adjacent to the
Duwamish  River and the Foster  Golf
Course. It is a dual-fuel (gas and/or No.
6 oil) water-tube Cleaver-Brooks model
(Delta D-60) with a design capacity of
35,000 Ibs steam/hr. The oil burner is a
low-pressure air-atomizing type.  The
rated gas-fuel efficiency is 78%, so the
design  heat  input  is  46,000,000
Btu/hour. The furnace volume is 755 cu
ft in the immediate combustion zone,
excluding  the  upper radiant  section.
Typical stack temperatures at maximum
firing  are 550-560°F. The combustion
zone temperatures are in excess of
2200°F at  the back wall. A steam-
heated preheater is capable of raising
incoming  oil  temperatures  of  100-
240°F. The oil feed pressure is main-
tained by a gear pump, which is protec-
ted by a duplex 30-mesh strainer on the
suction side.
  The boiler operates at full modulation
from a low- to high-fire position, regula-
ted by steam pressure, which is directly
affected by steam demand. Since a PCB
destruction program would be required
to operate at a steady rate of waste fuel
consumption, there would be a change
from normal boiler operating practice. If
the fuel waste were consumed at maxi-
mum fuel feed rates, then some of the
generated  steam  would have to be
dumped  when process demands
dropped off. In the case of waste fuel
consumption at some intermediate rate,
auxiliary heating must be made up by
firing natural gas simultaneously during
high demand periods, and excess steam
would  have  to be dumped  at  low
demand conditions.
Recommendations on the
Feasibility of Using the
Seattle Rendering Boiler

Suitability of Yellow Grease as
Boiler Fuel
  The inspection  of a grease sample
from one of  the  contaminated ship-
ments (Fujitsuki Maru No. 1, port tank
09-15-79) produced the results, shown,

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in Table 1; two grades of fuel oil are
shown by comparison. These inspection
results  provide some confidence that
the grease could be burned undiluted,
since:

  •  The viscosity is between that of
     No.  5  and No.  6 fuel oil,  so
     atomization should be good with a
     burner that is usually run with No.
     6 oil.

  •  The fuel value of the grease is 93%
     of a No. 6 oil value.

  •  The ash content is low.

  Furthermore,   Pierce  Packing*
confirmed that they had burned 600,-
000 Ibs of grease in their steam boiler,
with good combustion characteristics.
Estimated Destruction
Efficiency
  The residence time of the PCB's in the
furnace combustion zone has  to be
determined as part of the evaluation of
destruction efficiency. At a waste feed-
rate  of  6  gpm, the actual volumetric
flowrate of combustion gases through
the 755-cu ft furnace volume is 43,097
acfm, yielding a residence time  of 1.1
seconds. The  residence  time will be
twice as long  at a feedrate of 3 gpm,
since the gas volumetric rate is half as
much.
  The estimated destruction efficiencies
under these conditions  depend  on a
number of factors, including:

  •  Comparison of residence.time and
     temperature to those specified in
     40 CFR, Part 761, Subpart E:
     1200°C (2191 °F) @ 2 seconds, or
     1600°C (2912°F) @ 1.5 seconds
     dwell:  (these  conditions are for
     waste  incinerators,  burning  PCB
     wastes of any  concentration).

  •  Estimated  efficiency  of  the
     Cleaver-Brooks burner,  and the
     ease of atomization  of the grease
     fuel, as compared to No. 6 fuel oil.

  •  The likelihood  of achieving high
     destruction efficiencies with PCB
     concentrations of a  few hundred
     ppm, vs. percentage range con-
     centrations found in some other
     wastes  (it's  always  easier  to
     remove  high percentages of high
     concentrations).  A  99.9%
     destruction  efficiency  is often
     obtained  with   high  efficiency
     incinerators  and  high  PCB
     concentrations.

  The likelihood of achieving 99.9 + %
PCB destruction is estimated to be very
good at a 3 gpm feedrate, since the time
and temperature  relationships may
approximate those of  good incinerator
practice. It is less certain that a 6 gpm
feedrate would yield  equivalent de-
struction efficiency, but the operation at
6 gpm would certainly be preferred for
reducing the program length. Therefore,
the verification test should determine
the destruction efficiency and combus-
tion temperature at both feedrates.
  The boiler operation under automatic
control will allow full  modulation from
low- to high-fire, regulated  by steam
pressure. High-fire fuel demand would
be about 6 gpm, since the Btu content of
grease and No. 6 oil are similar. Low-fire
demand  is about 25% of high fire,  or
about 1.5 gpm.
  Although the Cleaver-Brooks boiler at
Seattle  Rendering does not  meet the
standard prerequisite of 50 million Btu/
hr heat input (at full output), it comes
close at 46 million Btu/hr.
  It is recommended that the standard
prerequisite of a maximum blend of 10%
waste (with  the remainder fuel oil) is
less appropriate for the Seattle Render-
ing program than a 100% waste fuel
choice. The 10% blend is based on the
possibility of using any waste, including
those with very low fuel value. As  al-
ready noted, the Btu content of yellow
grease is very close to No. 5 or No. 6 fuel
oils, and the combustion characteristics
are judged to be good. Furthermore,
there are no facilities available for
blending grease and fuel oil.
Environmental Impact
  The anticipated impact of PCB waste
burning at the Seattle Rendering facility
was modeled with a point-source dis-
persion model, actual stack dimensions,
and a range of local meteorological con-
ditions, as reported from the PSAPCA*
•Billings, MT.
"Puget Sound Air Pollution Control Agency.
 station  at  Tuckwila/South  Center,
 about 2 miles south of the plant.
   The flat-terrain  dispersion model is
 only useful for impact analysis up to the
 point of a significant terrain change. The
 prevailing winds at the source location
'(35% of the time)  are south to south-
 west,  with neutral (Class "D") atmos-
 pheric stability.
   There is a sharp terrain rise of 50 m
 only 400 m in a prevailing (SSW) direc-
 tion from the rendering plant source.
 The calculated effective stack height is
 40-65 m. Model predictions at 400 m of
 PCB   concentrations  at  the  plume
 centerline (which is a worst-case condi-
 tion) are as follows:


 Feed  Wind   No PCB   99.9% PCB
 Rate   Speed  Destruction Destruction
 gpm   m/sec    figm3       ng/m3

  6     10       6.4         6.4

  6      4      16.4        16.0

  3     10        1.6         1.6

  3      4       4.0         4.0
  The modeling estimates are based on
 calculated  emission  quantities  as
 follows:

  •   6 gpm feedrate using worst-case
      of 400 ppm PCB's: 9110 scfm
      stack  discharge,   0.12  g/sec
      uncontrolled, 0.12  mg/sec con-
      trolled emission rates.

  •   3 gpm feedrate, using moderate-
      case of 175 ppm PCB's: 4555 scfm
      stack discharge, 0.03 g/sec  un-
      controlled, 0.03 mg/sec control-
      led emission rates.

  The ground-level concentration of the
 plume under flat-terrain assumptions
 may  be more  realistic at 1.5 to 2  km
 downwind, after the  plume has passed
 over  the  bluff. The  atmospheric PCB
 concentrations for a 99.9% efficient de-
 struction operation are in the range of
 0.1 to 0.4 ng/m3.
  Techniques for ambient monitoring of
 these extemely low PCB concentrations
 are still being developed, but it is recom-
 mended that an  attempt be  made to
 make such a measurement at the most
 likely downwind position, in support of
 the verification test.

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  An analysis of downwash concentra-
tions of PCB's was also done, using the
building as an area source. In a down-
wash  model, dispersal  of  pollutants
occurs in the immediate, ground level
vicinity of a source, rather than through
an elevated plume. Calculated atmos-
pheric concentrations of PCB's were
estimated to be around 0.2 ng/m3 with
99.9% destruction. The OSHA limit for
worker exposure to PCB's on an 8-hour
day, 40-hour  week basis is 1 mg/m3
with 42% PCB chlorine content, so that
the downwash concentration certainly
does not threaten worker safety.
Shuffleton Power Plant
Analysis

Facility Operation Background
  The Shuffleton Power Plant, owned
by the Puget Sound Power and Light
Co.,  (PSPL), is  located at 1101 Lake
Washington  Blvd.,  Renton, WA.
Shuffleton is operated at a steady level
of 330,000 Ib/hr of steam in each of
three oil-fired  boilers. The Shuffleton
boilers are  balanced draft type (FD, ID
fans); there are 16 Peabody mechanical
burners in  each boiler, burning No.  6
fuel oil heated to 200°F.
  The available measurements include
air/fuel ratio,  oil  pressure,  windbox
pressure, furnace draft, fuel oil temper-
ature, air  preheater temperature  and
pressure, and oxygen in the stack gases.
Fuel oil is  not  presently metered, al-
though an orifice exists  in the fuel oil
line.
  The fuel  oil  is supplied from large
storage  tanks  to two smaller service
tanks, each having a working capacity of
800 bbls. The tanks are run alternately,
on about a 5-hour cycle, while 3600 to
3900 bbl per day  of fuel oil  are con-
sumed. The tanks have open hatches at
the top which could  be used for pumping
in other fuels to get a mixed fuel.  The
fuel is kept at 150°F in the service tanks.
The fuel oil is pumped out of the service
tanks by three 80 gpm pumps, and  dis-
tributed through heat  exchangers to
raise the fuel temperature to 200°F. The
fuel  is then injected into each of the
burners in the three boilers. The viscos-
ity of No. 6 oil is sufficiently lowered by
the 200°F preheat to get good burner
and combustion performance.
  The  operations  of  the Shuffleton
power plant are not  expected to be
hindered by the proposed PCB waste
incineration, as indicated by the follow-
ing discussion on feasibility. Three-shift
operations coverage of the boiler and
fuel  handling system will  provide the
necessary surveillance of combustion
performance that is  needed for PCB
incineration. There is reason to believe
that close surveillance is mandatory for
maintaining  good  combustion  at
Shuffleton.  The   plant has  received
frequent citations for opacity violations,
despite a test of the No. 1 boiler which
showed paniculate emissions within
compliance.  A  combustion  consul-
tant's report submitted to Puget Power
identified  possible  causes  of  poor
combustion to  include inadequate fuel
atomization (due to lowfuel oil tempera-
ture) and dirty burner.
Recommendations on the
Feasibility of Using the
Shuffleton Boilers for PCB
Waste Incineration

Suit ability of Yellow
Grease as a Boiler Fuel
  The first consideration for suitability
is  the determination of  miscibility, or
degree of mixing, of grease and No. 6
fuel oil, since  using a blended fuel is
technically  the simplest method  for
waste  incineration  in a  large boiler.
Yellow grease and No. 6 fuel oil mixing
tests  were conducted by Northwest
Laboratories at two blend ratios (10%
and 30% grease,  by volume) and two
temperatures (180°F and 200°F). The
results of these four tests were consis-
tent; the blends were miscible, with no
stratification, at all conditions.
  The inspection  of a grease sample
from one of the contaminated batches
by Northwest Laboratories produced the
results reported in Table 1; two grades
of fuel oil are shown by comparison.
  The previous inspection results pro-
vide further confidence that the grease
will combust well with No. 6 fuel oil.
since:
     The viscosity is between that of
     No. 5 and No. 6 fuel oil, so burner
     atomization with the blended fuel
     should be good.

     The fuel value of the grease is 93%
     of a No. 6 oil value.

     The ash content is low.
Estimated Destruction
Efficiency
  The residence time of the PCB's in the
boiler combustion zone is a considera-
tion in the evaluation of destruction effi-
ciency. At a typical fuel feedrate of 38
gpm, and 4-5% excess oxygen, the cal-
culated rate of combustion gas flow is
1111 std cu ft/sec. The estimated resi-
dence time in the lower half of the boiler
is  2.5  seconds, with   another  2.5
seconds dwell in  the upper zone. The
temperature in the combustion zone, in
the vicinity  of the burners, has been
measured at 2800°F.
  The estimated destruction efficiencies
under these conditions  depend on a
number of factors, including:

  •  Comparison of residence time and
     temperature to those specified in
     40  CFR, Part  761, Subpart  E:
     1200°C (2192°F) @ 2 seconds, or
     1600°C (2912°F) @ 1.5 seconds
     dwell:  (these conditions are for
     waste incinerators,  burning  PCB
     wastes of any  concentration).

  •  Efficiency of the  burners and the
     ease of atomization of the grease
     and No. 6 fuel  oil blend.

  •  The likelihood  of achieving high
     destruction efficiencies  with
     blended  PCB  concentrations  of
     less than 100 ppm, vs. percentage
     range  concentrations  found  in
     some other wastes (it's  always
     easier to remove high percentages
     of high concentrations). A 99.9%
     destruction efficiency is often ob-
     tained with high  efficiency incin-
     erators and  high PCB concentra-
     tions.

  The  likelihood  of achieving  99.9%
PCB destruction is estimated to be good,
given the similarity of the boiler condi-
tions to good incinerator  practice, and
the compatibility of the grease and No. 6
fuel oil.
  It is recommended that the PCB incin-
eration be conducted with a grease-to-
fuel oil  ratio of 30/70 instead  of the
standard prerequisite  ratio  of  10/90.
There are good arguments for using a
30% blend, since the length of time
needed to  complete the effort will be
shortened by a proportionate amount,
and the grease is not expected to cause
any combustion problems or available
heat  reductions.  The environmental
consequences of burning a 30% blend,
and the logistical limitations of support- |

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Table  1.    Laboratory Inspections
                            Grease
Viscosity
SUS @ 122°F
SUS @ 200°F
Density, Ib/gal
@ 122°F
@ 180°F
Btu/lb
Moisture %
Water & Sediment %
Carbon %
Hydrogen %
Oxygen %
Sulfur %
Ash %
143.7
59.8

7.459
7.266
16.779
0.41
2.8
76.6
11.9
10.5
0.01
0.12
40

@ 60°, 8.0
18,250
0.05
1
87.5
10.2
—
1.1
—
300

@ 60°, 8.33
18,000
0.05
2
88.3
9.5
—
1.2
0.1
                                        worker exposure on an 8-hour day, 40-
                                        hour week basis is 1 mg/m3 with 42%
                                        chlorine content in the PCB's.
 No. 5 Fuel Oil       No. 6 Fuel Oil         Techniques for ambient monitoring of
                                        these extremely low PCB concentra-
                                        tions are still being developed, but it is
                                        recommended that an attempt be made
                                        to make such  a measurement at the
                                        most likely downwind position, in sup-
                                        port of the verification test.
                                                                                                   Stability Class

                                                                                                  FED

                                                                               Data Factor—    3.95   2.11   0.027

                                                                               Location of
                                                                               max.  1 hr
                                                                               PCB con-
                                                                               concentration at 2 km   2km   12km
                                                                               groundlevel       NE     NE      NE
ing a higher grease percentage,  are
discussed below.
Environmental Impact
  The anticipated impact of PCB waste
burning at Shuffleton power plant was
modeled with the EPA "Valley" model,
which  takes into account a  certain
amount of terrain variation. The com-
puter program was run by the  PSPL
quality control staff, using terrain and
stack dimension parameters already set
up for the Shuffleton plant and vicinity.
  The model was run with a low wind
speed of 2.5 m/sec and a prevailing
southwest wind, over a range of atmos-
pheric  stability  conditions. The  most
stable conditions ("F" stability) usually
yield the highest ground concentrations
of a pollutant, since dispersion by  air
mixing is minimal. The following nor-
malized data factors were computed for
stability Classes A through F (A being
the most unstable). The data factors are
multiplied by  an estimated  emission
rate to get a maximum 1-hour concen-
tration  at   the  indicated downwind
distance.
  The maximum 1 -hour PCB concentra-
tion can then be estimated using "F"
stability conditions, from the emission
rates determined as follows:
  a.  10% blend, 3200 gal of 400 ppm
     (worst-case) grease burned over a
     5-hour period yield 0.24 g/sec(no
     control), or 0.24 mg/sec (99.9%
     controlled) emission rate.

     Worst-case model prediction for
     downwind  PCB concentration =
     3.95  x 0.24 = 0.9  fjg/m3 (no
     control), or 0.9 ng/m3(99.9% con-
     trol) at 2 km NE of plant.

  b.  30% blend  yields three times the
     emission rate above—0.71 g/sec
     (no control), or 0.71 mg/sec (99.9%
     control).

     Estimated  downwind   PCB con-
     centration at 2 km NE then will be:
     2.7 fjg/m3 (no control), or 2.7
     ng/m  (99.9% control).

  These estimates can be compared to
the OSHA exposure limit for PCB's. The
OSHA   allowable  concentration  for
Data Factor —
      Stability Class

    C       B      A

0.129   0.245    0.20
Location of
max. 1 hr
PCB con-
concentration at 4 km
groundlevel       NE
        2km
          NE
 near
plant

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J. E. Cotter and R. J. Johnson are with TRW, Inc., Redondo Beach, CA 90278.
David C. Sanchez is the EPA Project Officer (see below).
The complete report, entitled "Facilities Evaluation of High Efficiency Boiler
  Destruction PCB Waste," (Order No. PB 81-178 287; Cost: $6.50, subject to
  change) will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project Officer can  be contacted at:
        Industrial Environmental Research Laboratory
        U.S.  Environmental Protection Agency
        Research Triangle Park,  NC 27711
                                                                       
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