NC0038377_Table 6-7 Input Parameters and Values for CD Flow Equation_20160229

TABLE 6-7
INPUT PARAMETERS AND VALUES FOR CONVECTIVE -DISPERSIVE
FLOW EQUATION BASED UPON MAYO DATA
MAYO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, ROXBORO, NC
Parameter
Nomenclature
Value
Source of Value
Began Sluicing Ash
-
1983
CSA
Ceased Sluicing
-
2016*
CSA
Duration of Source
t°
34
Calculated
Term
3.45 arsenic,
Max value from
Source Concentration
c°
1870 boron
Seepage Data in
(Ng/L)
3370 manganese
2015 Table - ,
CAP Part 1
Background
1 arsenic
Lowest Provisional
Concentration
c;
50 boron,
Background or
(pg/L)62
manganese
Detection Limit
Geometric Means of
Hydraulic Conductivity
Surficial, Transition,
(ft/yr)
k
72.8
and Bedrock
Table 3-2,
CAP Part 1
Average
Hydraulic Gradient
i
0.026
of gradients
Table 3-3,
CAP Part 1
Effective Porosity
n,
0.1
CSA
Seepage Velocity
vs=ki/ne
18.7
Calculated
ft/ r
Dis ersivit ft
a
20
0.1*2000
Dispersion ft2/ r
D = ays
375
Calculated
Distribution Coefficient
50 arsenic,
W/O
Kd
0.12 boron,
Murdoch et a/.,2015
0.1 manganese
Time from Introduction
t
Varies
To capture the
of Constituent ears
length of plume
Distance from
Measured (basin to
Boundary of Ash Basin
x
500
Crutchfield Branch
(feet)
at compliance
boundary)
Calculated
c(x,t)
As shown in pg/L
Calculated
Concentration
Prepared By: KDB Checked By: DGN
* Assume that sluicing is terminated in 2016. The Mayo ash basin has been proposed as "low risk" and the
basin closure date is December 31, 2029.
** Groundwater entering Crutchfield Branch is primarily affected by the northern section of the basin. The max
observed seepage concentration for Boron and Arsenic from Round 1 and 2 sampling events is more
representative than the ash pore water values measured from the southern portion of the basin for this
model. Selecting the maximum concentration is a conservative approach. For manganese, the second
highest value was selected because the highest value was recorded from a sample with very high turbidity.
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