HomeMy WebLinkAboutRA-550_3530_CA_LTRRPT_20230816_FT ModelWithersRavenel
Our People. Your Success.
115 MacKenan Drive | Cary, NC 27511
t: 919.469.3340 | f: 919.467.6008 | www.withersravenel.com | License No. F‐1479
Asheville | Cary | Charlotte | Greensboro | Lumberton | Pittsboro | Raleigh | Southern Pines | Wilmington
August 16, 2023
State of North Carolina
Department of Environmental Quality
Federal & State Lead Program
Division of Waste Management‐Underground Storage Tank Section
1646 Mail Service Center
Raleigh, North Carolina 27699‐1646
Attn: Ms. Linda Blalock
Reference: Letter Report – Contaminant Fate & Transport Model
Cary Ceramics Supply
2166 (2186) North Salem Street
Cary, Wake County, North Carolina
Groundwater Incident Number: 3530
UST Number: RA‐550
NCDEQ Contract # N70522‐C
WR Project Number: 02140214.72
Ms. Blalock,
WithersRavenel, Inc. (WR) has prepared this Letter Report documenting the completion of
Contaminant Fate & Transport (F/T) Modelling for the release associated with the former Cary
Ceramics Supply site in Cary, Wake County, North Carolina. Activities outlined herein were
completed under NCDEQ Contract # N70522‐C, Task Authorization (TA) 02 for the site, issued by
NCDEQ on August 2, 2023.
Background
In July 1987, the Raleigh Regional Office (RRO) Groundwater Section received an anonymous call
that a strong gasoline odor was present in the Cary Ceramics Supply bathroom. The facilities’ water
supply well was sampled on July 24, 1987 and found to contain 1,200 µg/L benzene and 160 µg/L
1,2‐dichlorethane, among other gasoline‐related contaminants. The supply well was observed to be
29 ft deep and at the time of sampling had 8.86 ft of water in the well.
Following discovery of a release on the property, one 8,000 gal, three 2,000 gal and one 1,000 gal
USTs were closed by removal at the location in June 1988. No information is available indicating
the contents of these tanks. Prior to redevelopment in the late 1990’s, the site had been the
location of Cary Ceramics Supply. Before use by Cary Ceramics Supply, the property was
reportedly the location of a “Q Truck Stop”, which sold retail gasoline and diesel fuel through 1960.
The USTs were reportedly installed in 1945 and were reported by previous consultants to have
been the source(s) of the release on the site. A “grease pit” and “waste oil vault” utilized for
servicing trucks at the facility were also located on the site. A single 100‐gal heating oil AST was
located at the rear of the former Cary Ceramics Supply building.
WithersRavenel
Our People. Your Success.
Cary Ceramics WR Project # 23‐0307‐AL
Letter Report – Contaminant Fate & Transport Modeling August 2023
This tank was removed from the site at some point prior to redevelopment of the parcel in the late
1990s.
Subsequent to removal of the USTs on the property and during/following redevelopment at the
location, various assessment activities have been completed at the site. Those assessment activities
are referenced and/or documented in previous reports associated with the site.
Contaminant Fate & Transport Modelling – August 2023
In an effort to determine the potential future impact of the groundwater contamination at the site
to off‐site receptor(s), WR was tasked with completion of a contaminant F/T Model for the site.
The F/T Modelling for the location as documented herein is based on previous assessment at the
location, slug testing performed at the site in May 2021, and the most recent groundwater sampling
completed at the location during June 2023.
WR performed the water level recovery tests on May 26, 2021. Test data were recorded using a
LevelTroll 700 pressure transducer and associated software. The recorded water level recovery
measurements and well construction dimensions were used to calculate an estimate of aquifer
hydraulic conductivity according to the method of Bouwer, 1989. The calculated hydraulic
conductivity (K) values are summarized in the table below:
Results of Aquifer Slug Testing
Well ID Test Type K (ft/day) K (cm/sec)
MW‐4 Recovery 0.79 2.8 x 10‐4
MW‐8 Recovery 2.7 9.4 x 10‐4
The derived K values are considered to be representative of the range of hydraulic conductivities
for the weathered Piedmont rock typical of the Cary NC area. Therefore, the average of the derived
K values (1.75 ft/day or 6.1 x 10‐4 cm/sec) was used in predictive modeling, as described in the
following section. A hydraulic gradient of 0.018 ft/ft was determined from water table elevations
measured in site monitoring wells on June 6, 2023. The K calculations are attached.
1. Contaminant Fate & Transport Modeling
WR used EPA’s BIOSCREEN® Natural Attenuation Decision Support System Model (Air Force
Center for Environmental Excellence) to simulate steady state migration and natural attenuation of
the dissolved phase hydrocarbons in the surficial aquifer using the Domenico analytical solute
transport model. This model considers advection, dispersion, absorption, aerobic decay, and
anaerobic reactions that result in the natural biodegradation of petroleum compounds over
specified times.
WithersRavenel
Our People. Your Success.
Cary Ceramics WR Project # 23‐0307‐AL
Letter Report – Contaminant Fate & Transport Modeling August 2023
Contaminant of Concern:
Benzene is the petroleum‐related volatile organic compound (VOC) that is currently present at the
highest concentrations in groundwater near the source area at the site, which occurs in the vicinity
of monitoring wells MW‐8 and MW‐9. Lower concentrations of benzene were detected in wells
further from the source area (See Table B‐4 and Figure 5 of WR’s August 2, 2023 Monitoring
Report). Benzene has an organic carbon partitioning coefficient that is an order of magnitude lower
than the other main petroleum‐related VOCs (ethylbenzene, toluene, and xylene). Therefore, the
movement of benzene in groundwater is less attenuated in the subsurface than the other primary
petroleum‐related VOCs.
For the purpose of contaminant fate and transport modeling at the site, WR used the recently
detected highest concentration of benzene in the sample from MW‐9, and the presumed absence
of detectable petroleum constituents in the nearest surface water feature (about 500 feet west of
the site) and off‐site well, which is located approximately 900 feet to the northwest. The length of
the model simulation was therefore set to 900 feet, which includes the distance to the nearest
surface water feature. The model calculated anticipated concentrations of benzene along this flow
path at times 30 years and 100 years from the present.
It is noteworthy that the lateral extent of benzene in site groundwater (see Figure 5 of WR’s August
2, 2023 Monitoring Report) currently extends less than 100 feet from the source area near wells
MW‐8 and MW‐9. This implies that natural groundwater flow rates are relatively low, and that
natural attenuation processes have and are limiting the lateral migration of benzene within
groundwater.
Representative Concentrations:
Wells and benzene concentrations utilized in the model include:
Monitoring Well: MW‐9 (June 2023)
o Benzene – 2.85 mg/L
Surface Water: Stream approximately 500 feet to west
o Benzene – <0.001 mg/L (assumed)
Potable Supply Well: WSW‐13 approximately 900 feet to northwest
o Benzene – <0.001 mg/L (assumed)
The June 2023 benzene concentration detected in the sample from MW‐9 was used to establish
source area concentrations within the BIOSCREEN® model. For the purpose of the fate and
transport model, WR assumed an infinite source of sorbed contaminants, considered to be a
conservative or more extreme than expected modeling approach.
WithersRavenel
Our People. Your Success.
Cary Ceramics WR Project # 23‐0307‐AL
Letter Report – Contaminant Fate & Transport Modeling August 2023
Model Receptor Locations:
The nearest potential receptors are a surface water feature located about 500 feet to the west, and
potable water supply well WSW‐13 located about 900 feet to the northwest of the source area
near MW‐9. Therefore, the model runs consider a travel distance of 900 feet from MW‐9.
Site‐Specific Groundwater Parameters:
Groundwater parameters used in the model are based on field measurements, default values
obtained from the BIOSCREEN® manual and observed soil lithology at the site.
A hydraulic gradient of 0.018 ft/ft was derived from the water table elevation data for site
monitoring wells measured on June 6, 2023.
Hydraulic conductivity (K) is the average value derived from the recovery tests conducted at MW‐
4 and MW‐8 on May 26, 2021:
o 1.75 ft/day or 6.1 x 10‐4 cm/sec.
A porosity value of 30%, commonly associated with silty sandy residual soils derived from rocks
of the Piedmont Geologic Province.
Plume dimensions used in calculating dispersivity values are based on the June 2023 analytical
results.
Soil parameters including bulk density (1.7 kg/L) fraction of organic carbon (0.001) and organic
carbon partitioning coefficient (Koc) for benzene were based on default values referenced in the
BIOSCREEN user manual. The following Koc value was used:
o Benzene – 38 L/kg
The values used for instantaneous reaction parameters including nitrate, iron, and sulfate
concentrations were the lowest values cited in the BIOSCREEN user manual (zero mg/L for each
parameter). The average dissolved oxygen field reading (3.0 mg/L) obtained at the time of
sampling perimeter monitoring wells was used for the oxygen concentration input.
An average half‐life for benzene of 1 year was assumed from the range of half‐lives presented in
the BIOSCREEN manual, and the current distribution of this VOC in site groundwater.
Assignment of a 1 year half‐live is supported by the approximately 50% decrease in benzene
concentrations at locations MW‐2, MW‐7, MW‐8 and MW‐9 from June 2022 to June 2023.
2. Model Results
The BIOSCREEN software was used to simulate (1) transport with no degradation, (2) transport
with “instantaneous” biodegradation reaction, and (3) dispersion with 1st‐order decay, each over
30‐year and 100‐year durations. It should be noted that the source area impacts were
conservatively considered to be infinite, meaning that representative source area contaminant
concentrations do not decrease with time. In addition, BIOSCREEN uses simplified groundwater
flow conditions and assumes the aquifer and flow field are homogenous and isotropic and that
vertical flow gradients do not affect contaminant transport.
WithersRavenel
Our People. Your Success.
Cary Ceramics WR Project # 23‐0307‐AL
Letter Report – Contaminant Fate & Transport Modeling August 2023
No Degradation: Predicted concentrations of benzene greatly exceed its 2L Standard of 0.001 mg/L at a
distances of 500 and 900 feet from the source area within both of the modeled timeframes.
Under these conditions, concentrations of benzene at a distance 500 feet from the source
area are calculated to be about 1.4 mg/L after 30 and 100 years. The predicted benzene
concentrations 900 feet from the source area after 30 years was 0.661 mg/L and 1.1 mg/L
after 100 years. However, benzene concentrations have been observed to be below or close
to the 2L Standard at distances less than 100 feet from the source area according to recent
and historical monitoring data. If No Degradation/constant source conditions existed, we
would expect to see much higher concentrations of benzene at a distance 100 feet from the
source, however that is not the case. Therefore, the constant source “No Degradation”
scenario is not representative of conditions at the site. Instantaneous Reaction: Predicted concentrations of benzene greatly exceed its 2L Standard of 0.001 mg/L at a
distances of 500 and 900 feet from the source area within both of the modeled timeframes
in the instantaneous reaction scenario. Under these conditions, concentrations of benzene at
a distance 500 feet from the source area are calculated to be about 1.4 mg/L after 30 and
100 years. The predicted benzene concentrations 900 feet from the source area after 30
years was 0.184 mg/L and 0.947 mg/L after 100 years. Please note, however, that the lowest
values cited in the BIOSCREEN manual (zero mg/L) were used for the Instantaneous Reaction
scenario due to a lack of actual values. This makes the output for this scenario very similar to
the No Degradation scenario primarily because constant source conditions apply. Therefore,
the “Instantaneous Reaction” scenario does not appear to be representative of conditions at
the site either. 1st Order Decay:
The graphs of predicted contaminant concentration versus time for the 1st Order Decay
scenarios for benzene in groundwater after 30 years and 100 years are reasonably close to
currently observed concentrations with respect to distance from the source area. The
calculated benzene concentrations at a distance 500 feet from the source area for both
modeled timeframes are less than 0.001 ug/L. The 1st Order Decay simulations imply that a
condition of steady state may exist at the site. This makes intuitive sense given the limited
extent of benzene in site groundwater, and because the original contaminant source (the UST
system) and associated contaminated soils have been removed from the site. This implies that
the residual concentrations of the contaminants are being lowered by natural attenuation
processes, including dilution, dispersion and aerobic biodegradation over time. The
applicability of using a solute half‐live of one year is further supported by the approximately
50% decrease in benzene concentrations at locations MW‐2, MW‐7, MW‐8 and MW‐9 from
June 2022 to June 2023.
WithersRavenel
Our People. Your Success.
Cary Ceramics WR Project # 23‐0307‐AL
Letter Report – Contaminant Fate & Transport Modeling August 2023
In summary, the modelling results for the “No Degradation” and “Instantaneous Reaction” scenarios
are overly conservative and are not representative of current site conditions. The results of the 1st
Order Decay scenarios are more consistent with observed site conditions, which are more
representative of a site where the primary source of groundwater contamination has been removed,
and natural attenuation processes are occurring to reduce VOC concentrations in groundwater over
time. The 1st Order Decay scenario results imply that a condition of steady state may exist, where
contaminant removal by natural processes does not allow for further lateral movement of the
contaminants within groundwater. Results of the BIOSCREEN predictive modeling are attached.
WithersRavenel appreciates the opportunity to be of service to the Federal & State Lead Program.
Should you have any questions regarding the attached, please do not hesitate to contact us at (919)
469‐3340.
Cordially,
WithersRavenel
Kevin B. Buchanan G. Matthew James, P.G.
Project Manager Director of Geosciences
Attachments:
A Hydraulic Conductivity Calculation Worksheets
B BIOSCREEN Fate & Transport Model Results
C Table B‐4, August 2, 2023 Monitoring Report
D Figure 5, August 2, 2023 Monitoring Report
ATTACHMENT A
Hydraulic Conductivity Calculation Worksheets
Well:MW-4 Conducted by:Bellis
Test Date:5/26/2021 Entered/date:06/01/21
Test Type:Water Level Recovery Checked/date: Bellis 6/1/21
WELL DATA CALCULATION OF K
SWL =4.95 (ft BTOC)K = [(rc^2 ln(Re/rw))/2Le]*(1/t)ln(yo/yt)Elapsed time Log y y WL
WD =15.00 (ft BTOC)(min)(ft)(ft BTOC)WD =15.00 (ft BGS)yo =1.551 (ft) from plot 0.083 0.19 1.551 6.501
DTSP =3.00 (ft BGS)yt =1.082 (ft) from plot 0.167 0.13 1.355 6.305
rc =0.083 (ft)t =0.917 (minutes) from plot 0.250 0.10 1.262 6.212
n = 0.30 ln(Re/rw) = 0.92 0.333 0.08 1.211 6.161
0.417 0.07 1.175 6.125
rw =0.33 (ft)0.500 0.06 1.153 6.103
rc (adjusted) = 0.19 (ft)K = 7.9E-01 (ft/day)0.583 0.06 1.138 6.088
0.667 0.05 1.127 6.077
0.750 0.05 1.116 6.0660.833 0.04 1.102 6.052
Le = 12 (ft)K = 2.8E-04 (cm/sec)0.917 0.04 1.093 6.043
Lw = 10.05 (ft)1.000 0.03 1.082 6.032
Le/rw = 36.36 1.083 0.03 1.077 6.027
H =40.00 (ft)1.167 0.02 1.059 6.009
1.250 0.03 1.063 6.013
1.333 0.02 1.059 6.009
1.417 0.02 1.054 6.004
Calculation of ln(Re/rw)1.500 0.02 1.047 5.9971.583 0.02 1.043 5.993
Where: Lw < H;1.667 0.02 1.037 5.9871.750 0.01 1.034 5.984
ln(Re/rw) = [{1.1/(ln(Lw/rw))}+{A+Bln((H-Lw)/rw)}/(Le/rw)]^-1= 2.27 1.833 0.01 1.026 5.976
1.917 0.01 1.020 5.97
Where: Lw = H;2.000 0.01 1.015 5.965
2.083 0.01 1.015 5.965
ln(Re/rw) = [{1.1/(ln(Lw/rw))}+{C/(Le/rw)}]^-1 = 2.63 2.167 0.00 1.007 5.9572.250 0.00 1.002 5.9522.333 0.00 1.002 5.9522.417 0.00 0.993 5.943
2.500 0.00 0.991 5.941
Calculation of Coefficients 2.583 0.00 0.994 5.944
Value range for Le/rw from Table of Coefficients 2.667 0.00 0.990 5.94
Le/rw A B C 2.750 -0.01 0.984 5.934
30 2.5 0.35 2.1 2.833 -0.01 0.983 5.933
40 2.75 0.45 2.45 2.917 -0.01 0.979 5.9293.000 -0.01 0.978 5.928
Interpolated values of A, B and C for Le/rw 3.083 -0.01 0.974 5.924
36.36 2.66 0.41 2.32 3.167 -0.01 0.970 5.92
3.250 -0.01 0.968 5.918
Coefficients Table 3.333 -0.02 0.965 5.9153.417 -0.02 0.959
5.909
Le/rw A Le/rw B Le/rw C
3.500 -0.02 0.963
5.913
4 1.75 4 0.25 4 0.75 3.583 -0.02 0.957 5.907
5 1.76 5 0.25 5 0.85 3.667 -0.02 0.953 5.903
6 1.77 6 0.25 6 0.90 3.750 -0.02 0.956 5.906
7 1.80 7 0.25 7 1.00 3.833 -0.02 0.958 5.908
8 1.83 8 0.25 8 1.10 3.917 -0.02 0.949 5.899
9 1.90 9 0.25 9 1.20 4.000 -0.02 0.947 5.897
10 1.95 10 0.25 10 1.30 4.083 -0.02 0.948 5.898
15 2.10 15 0.27 15 1.50 4.167 -0.02 0.946 5.896
20 2.23 20 0.29 20 1.75 4.250 -0.03 0.938 5.888
25 2.40 25 0.31 25 1.90 4.333 -0.03 0.938 5.888
30 2.50 30 0.35 30 2.10 4.417 -0.03 0.935 5.885
40 2.75 40 0.45 40 2.45 4.500 -0.03 0.934 5.884
50 3.00 50 0.50 50 2.70 4.583 -0.03 0.933 5.883
60 3.45 60 0.52 60 3.00 4.667 -0.03 0.935 5.885
70 3.70 70 0.60 70 3.40 4.750 -0.03 0.930 5.88
80 3.90 80 0.65 80 3.60 4.833 -0.03 0.926 5.876
90 4.20 90 0.70 90 3.85 4.917 -0.03 0.926 5.876
100 4.50 100 0.75 100 4.20 5.000 -0.03 0.926 5.876
150 5.45 150 0.98 150 5.70 5.083 -0.03 0.929 5.879
200 6.10 200 1.20 200 7.00 5.167 -0.03 0.925 5.875
250 6.70 250 1.30 250 8.00 5.250 -0.04 0.919 5.869
300 7.10 300 1.50 300 8.80 5.333 -0.04 0.919 5.869
400 7.75 400 1.90 400 9.90 5.417 -0.03 0.924 5.874
500 8.20 500 2.20 500 10.60 5.500 -0.03 0.926 5.876
600 8.50 600 2.33 600 11.10 5.583 -0.04 0.919 5.869
700 8.70 700 2.50 700 11.50 5.667 -0.04 0.916 5.866
800 8.90 800 2.70 800 11.80 5.750 -0.04 0.915 5.865
900 9.00 900 2.75 900 12.00 5.833 -0.04 0.908 5.858
1000 9.20 1000 2.83 1000 12.40 5.917 -0.04 0.917 5.867
1500 9.50 1500 3.18 1500 12.90 6.000 -0.04 0.915 5.865
Reference: Bouwer(1989), Bouwer and Rice(1976)
TEST DATA
W&R Project No. 02170214.72
Hydraulic Conductivity (K) Calculation Worksheet
Cary Ceramics, Cary, Wake County NC
0.010
0.100
1.000
10.000
0.000 1.000 2.000Residual Drawdown Y (ft)Elasped Time in minutes
Water Level Recovery vs Time: MW-4
Yt
Yo
Well:MW-8 Conducted by:Bellis
Test Date:5/26/2021 Entered/date:06/01/21
Test Type:Water Level Recovery Checked/date: Bellis 6/1/21
WELL DATA CALCULATION OF K
SWL =8.41 (ft BTOC)K = [(rc^2 ln(Re/rw))/2Le]*(1/t)ln(yo/yt)Elapsed time Log y y WL
WD =15.00 (ft BTOC)(min)(ft)(ft BTOC)WD =15.00 (ft BGS)yo =1.615 (ft) from plot 0.0833 0.21 1.615 10.025DTSP =3.00 (ft BGS)yt =0.751 (ft) from plot 0.1667 0.12 1.327 9.737rc =0.083 (ft)t =0.583 (minutes) from plot 0.2500 0.04 1.095 9.505
n = 0.30 ln(Re/rw) = 0.92 0.3333 -0.03 0.942 9.352
0.4167 -0.07 0.846 9.256
rw =0.33 (ft)0.5000 -0.10 0.794 9.204
rc (adjusted) = 0.19 (ft)K = 2.7E+00 (ft/day)0.5833 -0.12 0.766 9.176
0.6667 -0.12 0.751 9.1610.7500 -0.13 0.736 9.1460.8333 -0.14 0.720 9.13Le = 12 (ft)K = 9.4E-04 (cm/sec)0.9167 -0.15 0.713 9.123
Lw = 6.59 (ft)1.0000 -0.15 0.705 9.115
Le/rw = 36.36 1.0833 -0.16 0.695 9.105
H =40.00 (ft)1.1667 -0.16 0.691 9.101
1.2500 -0.17 0.682 9.092
1.3333 -0.17 0.677 9.0871.4167 -0.17 0.672 9.082 Calculation of ln(Re/rw)1.5000 -0.17 0.670 9.081.5833 -0.18 0.661 9.071Where: Lw < H;1.6667 -0.18 0.658 9.068
1.7500 -0.18 0.658 9.068
ln(Re/rw) = [{1.1/(ln(Lw/rw))}+{A+Bln((H-Lw)/rw)}/(Le/rw)]^-1= 2.00 1.8333 -0.19 0.650 9.06
1.9167 -0.19 0.649 9.059
Where: Lw = H;2.0000 -0.19 0.641 9.051
2.0833 -0.19 0.639 9.049 ln(Re/rw) = [{1.1/(ln(Lw/rw))}+{C/(Le/rw)}]^-1 = 2.33 2.1667 -0.19 0.639 9.0492.2500 -0.19 0.641 9.0512.3333 -0.20 0.631 9.041
2.4167 -0.20 0.629 9.039
2.5000 -0.20 0.624 9.034
Calculation of Coefficients 2.5833 -0.20 0.628 9.038
Value range for Le/rw from Table of Coefficients 2.6667 -0.20 0.631 9.041
Le/rw A B C 2.7500 -0.21 0.621 9.03130 2.5 0.35 2.1 2.8333 -0.21 0.619 9.02940 2.75 0.45 2.45 2.9167 -0.21 0.618 9.0283.0000 -0.21 0.614 9.024
Interpolated values of A, B and C for Le/rw 3.0833 -0.21 0.611 9.021
36.36 2.66 0.41 2.32 3.1667 -0.21 0.612 9.022
3.2500 -0.22 0.608 9.018
Coefficients Table 3.3333 -0.22 0.602 9.012
3.4167 -0.22 0.602 9.012Le/rw A Le/rw B Le/rw C 3.5000 -0.22 0.598 9.0084 1.75 4 0.25 4 0.75 3.5833 -0.22 0.603 9.0135 1.76 5 0.25 5 0.85 3.6667 -0.22 0.603 9.0136 1.77 6 0.25 6 0.90 3.7500 -0.23 0.587 8.997
7 1.80 7 0.25 7 1.00 3.8333 -0.22 0.597 9.007
8 1.83 8 0.25 8 1.10 3.9167 -0.23 0.592 9.002
9 1.90 9 0.25 9 1.20 4.0000 -0.23 0.590 9
10 1.95 10 0.25 10 1.30 4.0833 -0.23 0.588 8.998
15 2.10 15 0.27 15 1.50 4.1667 -0.23 0.591 9.00120 2.23 20 0.29 20 1.75 4.2500 -0.23 0.586 8.99625 2.40 25 0.31 25 1.90 4.3333 -0.23 0.585 8.99530 2.50 30 0.35 30 2.10 4.4167 -0.23 0.584 8.994
40 2.75 40 0.45 40 2.45 4.5000 -0.23 0.587 8.997
50 3.00 50 0.50 50 2.70 4.5833 -0.24 0.579 8.989
60 3.45 60 0.52 60 3.00 4.6667 -0.25 0.568 8.978
70 3.70 70 0.60 70 3.40 4.7500 -0.24 0.578 8.988
80 3.90 80 0.65 80 3.60 4.8333 -0.24 0.575 8.98590 4.20 90 0.70 90 3.85 4.9167 -0.24 0.580 8.99100 4.50 100 0.75 100 4.20 5.0000 -0.24 0.575 8.985150 5.45 150 0.98 150 5.70 5.0833 -0.24 0.570 8.98
200 6.10 200 1.20 200 7.00 5.1667 -0.24 0.573 8.983
250 6.70 250 1.30 250 8.00 5.2500 -0.25 0.567 8.977
300 7.10 300 1.50 300 8.80 5.3333 -0.25 0.567 8.977
400 7.75 400 1.90 400 9.90 5.4167 -0.25 0.568 8.978
500 8.20 500 2.20 500 10.60 5.5000 -0.25 0.565 8.975600 8.50 600 2.33 600 11.10 5.5833 -0.25 0.565 8.975700 8.70 700 2.50 700 11.50 5.6667 -0.25 0.565 8.975800 8.90 800 2.70 800 11.80 5.7500 -0.25 0.564 8.974900 9.00 900 2.75 900 12.00 5.8333 -0.25 0.560 8.97
1000 9.20 1000 2.83 1000 12.40 5.9167 -0.25 0.557 8.967
1500 9.50 1500 3.18 1500 12.90 6.0000 -0.25 0.561 8.971
Reference: Bouwer(1989), Bouwer and Rice(1976)
TEST DATA
W&R Project No. 02170214.72
Hydraulic Conductivity (K) Calculation Worksheet
Cary Ceramics, Cary, Wake County NC
0.010
0.100
1.000
10.000
0.0000 1.0000 2.0000Residual Drawdown Y (ft)Elasped Time in minutes
Water Level Recovery vs Time: MW-8
Yt
Yo
ATTACHMENT B
BIOSCREEN Fate & Transport Model Results
BIOSCREEN Natural Attenuation Decision Support System Cary Ceramics Data Input Instructions:
Air Force Center for Environmental Excellence Version 1.4 Benzene 115 1. Enter value directly....orRun Name 2. Calculate by filling in grey
1. HYDROGEOLOGY 5. GENERAL 0.02 cells below. (To restore
Seepage Velocity*Vs 37.9 (ft/yr)Modeled Area Length*900 (ft) formulas, hit button below).
or Modeled Area Width*120 (ft)Variable* Data used directly in model.
Hydraulic Conductivity K 6.1E-04 (cm/sec)Simulation Time* 30 (yr)20 Value calculated by model.Hydraulic Gradient i 0.018 (ft/ft) (Don't enter any data).
Porosity n 0.3 (-)6. SOURCE DATA
Source Thickness in Sat.Zone*15 (ft)
2. DISPERSION Source Zones:Longitudinal Dispersivity*alpha x 10.4 (ft)Width* (ft)Conc. (mg/L)*
Transverse Dispersivity*alpha y 1.0 (ft)20 0.0285 1
Vertical Dispersivity*alpha z 0.0 (ft)20 0.285
or 40 2.85
Estimated Plume Length Lp 180 (ft)20 0.285200.0285
3. ADSORPTION Source Halflife (see Help):
Retardation Factor*R 1.2 (-)Infinite Infinite (yr)View of Plume Looking Down
or Inst. React.1st Order
Soil Bulk Density rho 1.7 (kg/l)Soluble Mass infinite (Kg)Observed Centerline Concentrations at Monitoring Wells
Partition Coefficient Koc 38 (L/kg)In Source NAPL, Soil If No Data Leave Blank or Enter "0"
FractionOrganicCarbon foc 1.0E-3 (-)7. FIELD DATA FOR COMPARISON
Concentration (mg/L)2.85 1.0 .03 .001 .0 .0 .0 .0 .0 .0 .0
4. BIODEGRADATION Dist. from Source (ft)0 20 110 200 290 380 470 560 650 740 830
1st Order Decay Coeff*lambda 6.9E-1 (per yr)
or 8. CHOOSE TYPE OF OUTPUT TO SEE:
Solute Half-Life t-half 1.00 (year)
or Instantaneous Reaction Model
Delta Oxygen*DO 3 (mg/L)
Delta Nitrate*NO3 0 (mg/L)
Observed Ferrous Iron*Fe2+0 (mg/L)
Delta Sulfate*SO4 0 (mg/L)
Observed Methane*CH4 0 (mg/L)
Vertical Plane Source: Look at Plume Cross-Section
and Input Concentrations & Widthsfor Zones 1, 2, and 3
L
W
or
oror
or
12345
or
or
View Output
Paste Example Dataset
View Output Restore Formulas for Vs, Dispersivities, R, lambda, other
RUN CENTERLINE RUN ARRAY Help Recalculate This
DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0)
Distance from Source (ft)
TYPE OF MODEL 0 90 180 270 360 450 540 630 720 810 900
No Degradation 2.850 2.482 2.070 1.806 1.622 1.485 1.375 1.273 1.144 0.943 0.661
1st Order Decay 2.850 0.464 0.072 0.012 0.002 0.000 0.000 0.000 0.000 0.000 0.000
Inst. Reaction 2.850 2.482 2.068 1.796 1.596 1.438 1.303 1.168 0.978 0.655 0.184
Field Data from Site 2.850 1.000 0.030 0.001
Time:
30 Years
0.000
0.500
1.000
1.500
2.000
2.500
3.000
0 100 200 300 400 500 600 700 800 900 10Concentration (mg/L)Distance From Source (ft)
1st Order Decay Instantaneous Reaction No Degradation Field Data from Site
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TransverseDISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0)Distance (ft) Distance from Source (ft)Model to Display:0 90 180 270 360 450 540 630 720 810 90025 0.285 1.165 1.223 1.209 1.174 1.132 1.089 1.037 0.953 0.800 0.56913 2.850 2.075 1.816 1.634 1.496 1.388 1.297 1.209 1.093 0.905 0.6370 2.850 2.482 2.070 1.806 1.622 1.485 1.375 1.273 1.144 0.943 0.661-13 2.850 2.075 1.816 1.634 1.4961.388 1.297 1.209 1.093 0.905 0.637-25 0.285 1.165 1.223 1.209 1.1741.132 1.089 1.037 0.953 0.800 0.569MASS1.7E+3 1.5E+3 1.3E+3 1.2E+3 1.1E+3 1.1E+3 1.0E+3 9.5E+2 8.6E+2 7.2E+2 5.1E+2FLUX(mg/day)Time:30 YearsTarget Level: 0.005 mg/L Displayed Model: No DegradationPlume and Source Masses (Order-of-Magnitude Accuracy)Plume Mass if No Biodegradation18.3(Kg)- Actual Plume Mass18.3(Kg)= Plume Mass Removed by Biodeg0.0(Kg)0 %Change in Electron Acceptor/Byproduct Masses:Oxygen Nitrate Iron II Sulfate Methanena na na na na(Kg)Contam. Mass in Source (t=0 Years) infinite(Kg)Contam. Mass in Source Now (t=30Years) Infinite(Kg) Current Volume of Groundwater in Plume 6.4(ac-ft) Flowrate of Water Through Source Zone 0.469(ac-ft/yr)250-250.0000.5001.0001.5002.0002.5003.000090180270360450540630720810(ft)Concentration (mg/L)(ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All DataPlot Data > TargetMass HELP
TransverseDISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0)Distance (ft) Distance from Source (ft)Model to Display:0 90 180 270 360 450 540 630 720 810 90060 0.028 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.00030 0.285 0.806 0.911 0.916 0.888 0.848 0.801 0.737 0.616 0.376 0.0000 2.850 2.482 2.068 1.796 1.596 1.438 1.303 1.168 0.978 0.655 0.184-30 0.285 0.806 0.911 0.916 0.8880.848 0.801 0.737 0.616 0.376 0.000-60 0.028 0.000 0.000 0.000 0.0000.000 0.000 0.000 0.000 0.000 0.000MASS1.7E+3 1.6E+3 1.5E+3 1.4E+3 1.3E+3 1.2E+3 1.2E+3 1.0E+3 8.8E+2 5.6E+2 7.3E+1FLUX(mg/day)Time:30 YearsTarget Level: 0.005 mg/L Displayed Model: Inst. ReactionPlume and Source Masses (Order-of-Magnitude Accuracy)Plume Mass if No Biodegradation34.9(Kg)- Actual Plume Mass13.7(Kg)= Plume Mass Removed by Biodeg21.2(Kg)(61 %)Change in Electron Acceptor/Byproduct Masses:Oxygen Nitrate Iron II Sulfate Methane-66.6 +0.0 +0.0 +0.0 +0.0(Kg)Contam. Mass in Source (t=0 Years) infinite(Kg)Contam. Mass in Source Now (t=30Years) Infinite(Kg) Current Volume of Groundwater in Plume 9.2(ac-ft) Flowrate of Water Through Source Zone 0.469(ac-ft/yr)600-600.0000.5001.0001.5002.0002.5003.000090180270360450540630720810(ft)Concentration (mg/L)(ft)Recalculate No Degradation 1st Order Decay Instantaneous Plot All DataPlot Data > TargetMass HELP
Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0)
Distance (ft)Distance from Source (ft)Model to Display:
0 90 180 270 360 450 540 630 720 810 900
60 0.029 0.007 0.004 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000
30 0.285 0.153 0.034 0.007 0.001 0.000 0.000 0.000 0.000 0.000 0.000
0 2.850 0.464 0.072 0.012 0.002 0.000 0.000 0.000 0.000 0.000 0.000
-30 0.285 0.153 0.034 0.007 0.001 0.000 0.000 0.000 0.000 0.000 0.000
-60 0.029 0.007 0.004 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000
MASS 1.7E+3 3.1E+2 5.8E+1 1.1E+1 2.0E+0 3.7E-1 6.8E-2 1.3E-2 2.3E-3 4.3E-4 7.8E-5
FLUX
(mg/day)Time:30 Years Target Level: 0.005 mg/L Displayed Model: 1st Order Decay
Plume and Source Masses (Order-of-Magnitude Accuracy)
Plume Mass if No Biodegradation 18.3 (Kg)
- Actual Plume Mass 1.0 (Kg)
= Plume Mass Removed by Biodeg 17.3 (Kg)
(94 %)
Change in Electron Acceptor/Byproduct Masses:
Oxygen Nitrate Iron II Sulfate Methane
na na na na na (Kg)
Contam. Mass in Source (t=0 Years)infinite (Kg)
Contam. Mass in Source Now (t=30Years)Infinite (Kg)
Current Volume of Groundwater in Plume 4.5 (ac-ft)
Flowrate of Water Through Source Zone 0.469 (ac-ft/yr)
60
0
-60
0.000
0.500
1.000
1.500
2.000
2.500
3.000
0 90 180 270 360 450 540 630 720 810
(ft)Concentration (mg/L)(ft)Recalculate
No Degradation
1st Order Decay
Instantaneous
Plot All Data
Plot Data > Target Mass HELP
BIOSCREEN Natural Attenuation Decision Support System Cary Ceramics Data Input Instructions:
Air Force Center for Environmental Excellence Version 1.4 Benzene 115 1. Enter value directly....orRun Name 2. Calculate by filling in grey
1. HYDROGEOLOGY 5. GENERAL 0.02 cells below. (To restore
Seepage Velocity*Vs 37.9 (ft/yr)Modeled Area Length*900 (ft) formulas, hit button below).
or Modeled Area Width*120 (ft)Variable* Data used directly in model.
Hydraulic Conductivity K 6.1E-04 (cm/sec)Simulation Time* 100 (yr)20 Value calculated by model.Hydraulic Gradient i 0.018 (ft/ft) (Don't enter any data).
Porosity n 0.3 (-)6. SOURCE DATA
Source Thickness in Sat.Zone*15 (ft)
2. DISPERSION Source Zones:Longitudinal Dispersivity*alpha x 10.4 (ft)Width* (ft)Conc. (mg/L)*
Transverse Dispersivity*alpha y 1.0 (ft)20 0.0285 1
Vertical Dispersivity*alpha z 0.0 (ft)20 0.285
or 40 2.85
Estimated Plume Length Lp 180 (ft)20 0.285200.0285
3. ADSORPTION Source Halflife (see Help):
Retardation Factor*R 1.2 (-)Infinite Infinite (yr)View of Plume Looking Down
or Inst. React.1st Order
Soil Bulk Density rho 1.7 (kg/l)Soluble Mass infinite (Kg)Observed Centerline Concentrations at Monitoring Wells
Partition Coefficient Koc 38 (L/kg)In Source NAPL, Soil If No Data Leave Blank or Enter "0"
FractionOrganicCarbon foc 1.0E-3 (-)7. FIELD DATA FOR COMPARISON
Concentration (mg/L)2.85 1.0 .03 .001 .0 .0 .0 .0 .0 .0 .0
4. BIODEGRADATION Dist. from Source (ft)0 20 110 200 290 380 470 560 650 740 830
1st Order Decay Coeff*lambda 6.9E-1 (per yr)
or 8. CHOOSE TYPE OF OUTPUT TO SEE:
Solute Half-Life t-half 1.00 (year)
or Instantaneous Reaction Model
Delta Oxygen*DO 3 (mg/L)
Delta Nitrate*NO3 0 (mg/L)
Observed Ferrous Iron*Fe2+0 (mg/L)
Delta Sulfate*SO4 0 (mg/L)
Observed Methane*CH4 0 (mg/L)
Vertical Plane Source: Look at Plume Cross-Section
and Input Concentrations & Widthsfor Zones 1, 2, and 3
L
W
or
oror
or
12345
or
or
View Output
Paste Example Dataset
View Output Restore Formulas for Vs,
RUN CENTERLINE RUN ARRAY Help Recalculate This
DISSOLVED HYDROCARBON CONCENTRATION ALONG PLUME CENTERLINE (mg/L at Z=0)
Distance from Source (ft)
TYPE OF MODEL 0 90 180 270 360 450 540 630 720 810 900
No Degradation 2.850 2.482 2.070 1.806 1.622 1.485 1.378 1.291 1.219 1.157 1.105
1st Order Decay 2.850 0.464 0.072 0.012 0.002 0.000 0.000 0.000 0.000 0.000 0.000
Inst. Reaction 2.850 2.482 2.068 1.796 1.596 1.438 1.309 1.199 1.104 1.021 0.947
Field Data from Site 2.850 1.000 0.030 0.001
Time:
100 Years
0.000
0.500
1.000
1.500
2.000
2.500
3.000
0 100 200 300 400 500 600 700 800 900 10Concentration (mg/L)Distance From Source (ft)
1st Order Decay Instantaneous Reaction No Degradation Field Data from Site
Next Timestep
Prev Timestep
CalculateAnimation Recalculate This Return to
Transverse DISSOLVED HYDROCARBON CONCENTRATIONS IN PLUME (mg/L at Z=0)
Distance (ft)Distance from Source (ft)Model to Display:
0 90 180 270 360 450 540 630 720 810 900
60 0.029 0.007 0.004 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000
30 0.285 0.153 0.034 0.007 0.001 0.000 0.000 0.000 0.000 0.000 0.000
0 2.850 0.464 0.072 0.012 0.002 0.000 0.000 0.000 0.000 0.000 0.000
-30 0.285 0.153 0.034 0.007 0.001 0.000 0.000 0.000 0.000 0.000 0.000
-60 0.029 0.007 0.004 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000
MASS 1.7E+3 3.1E+2 5.8E+1 1.1E+1 2.0E+0 3.7E-1 6.8E-2 1.3E-2 2.3E-3 4.3E-4 7.8E-5
FLUX
(mg/day)Time:100 Years Target Level: 0.005 mg/L Displayed Model: 1st Order Decay
Plume and Source Masses (Order-of-Magnitude Accuracy)
Plume Mass if No Biodegradation Can't Calc.(Kg)
- Actual Plume Mass Can't Calc.(Kg)
= Plume Mass Removed by Biodeg - (Kg)
Change in Electron Acceptor/Byproduct Masses:
Oxygen Nitrate Iron II Sulfate Methane
na na na na na (Kg)
Contam. Mass in Source (t=0 Years)infinite (Kg)
Contam. Mass in Source Now (t=100Years)Infinite (Kg)
Current Volume of Groundwater in Plume Can't Calc.(ac-ft)
Flowrate of Water Through Source Zone Can't Calc.(ac-ft/yr)
60
0
-60
0.000
0.500
1.000
1.500
2.000
2.500
3.000
0 90 180 270 360 450 540 630 720 810
(ft)Concentration (mg/L)(ft)Recalculate
No Degradation
1st Order Decay
Instantaneous
Plot All Data
Plot Data > Target Mass HELP
ATTACHMENT C
Table B‐4, August 2, 2023 Monitoring Report
Calculated EPA‐504.1SampleIDDateCollectedBenzenen‐Butylbenzenesec‐ButylbenzeneDi‐isopropyl etherHexachloro‐1,3‐butadiene2‐HexanoneIsopropylbenzenep‐IsopropyltolueneMethyl tert‐butyl etherNaphthalenen‐PropylbenzeneToluene1,1,2‐Trichloroethane1,2,4‐Trimethylbenzene1,3,5‐TrimethylbenzeneTotal Xylenes1,2‐Dibromoethane (EDB)MW‐1 6/6/2023<0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <1.00 <1.00 <1.00 <0.500 <0.500 <0.500 <0.500 <0.500<0.500 <0.0204MW‐2 6/6/2023696<50.0 <50.0 669<50.0 <50.0 <50.0 <100 <100 543<50.0 771<50.0 1000 290 59800.446MW‐3 6/6/2023<0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <1.00 <1.00 <1.00 <0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <0.0206MW‐4 6/6/2023<0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <1.00 <1.00 <1.00 <0.500 <0.500 <0.500 <0.500 <0.500<0.500 <0.0204MW‐5 6/6/2023<0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <1.00 <1.00 <1.00 <0.500 <0.500 <0.500 <0.500 <0.500<0.500 <0.0207MW‐6 6/6/2023<0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <0.500 <1.00 <1.00 <1.00 <0.500 <0.500 <0.500 <0.500 <0.500<0.500 <0.0205MW‐7 6/6/20235.23<0.500 0.594<0.500 <0.500 1.98<0.500 <1.00 <1.00 7.76 1.12<0.500 0.513 12.5<0.500 7.39<0.0204MW‐8 6/6/2023548 0.646 1.22 15.2 1.47 7.76 0.859 1.15 3.12 89.4 3.87 2.4 0.682 67.6 2.04141 0.623MW‐9 6/6/20232850<50.0 <50.01230<50.081.9<50.0 <100 <100692 164 983<50.01350 4363930 3.371 70 70 70 0.4 40 70 25 20 6 70 600 0.6 400 400 500 0.025,000 5,900 8,800 70,000 400 40,000 30,500 11,700 20,000 6,000 26,100 260,000 600 28,500 24,100 50,000 50Notes:1)2)3)4)NL= Not ListedResult= Result Exceeds 2L StandardGCLs for Groundwater = NCDENR UST Section Gross Contamination Levels for Groundwater (Comprehensive Tables for Corrective Action Guidelines, September 2022 Version, Change 5).Compounds analyzed for by laboratory but not listed were not detected above laboratory detection limits. See the laboratory report included in the Appendix for a full list of constituents. NC 2L Standard GCLs for GroundwaterAll results provided in ug/L (micrograms per liter) or parts per billionNC 2L Standard ‐ North Carolina Groundwater Quality Standard as per NC Administrative Code 15A NCAC 02L (Comprehensive Tables for Corrective Action Guidelines, September 2022 Version, Change 5).Analytical MethodSM6200BTABLE B‐4BSUMMARY OF GROUNDWATER ANALYTICAL RESULTS ‐ ABBREVIATEDCary Ceramics SupplyIncident Number: 35302166 (2186) North Salem StreetApex, Wake County, NCPage 1 of 1
ATTACHMENT D
Figure 5, August 2, 2023 Monitoring Report
FORMERUST BASINFORMER CARYCERAMICS SUPPLYBUILDINGFORMERGREASE PITFORMERVAULTNO
R
T
H
S
A
L
E
M
S
T
R
E
E
T
BLDG2186BDLG2190BLDG2180MW-3MW-1MW-4MW-8MW-9MW-5(696)(0.704)(<0.5)(<0.5)(<0.5)(548)MW-6(<0.5)MW-2(5.23)MW-7(2,850)LEGENDTYPE II MONITORING WELL LOCATIONBENZENE CONCENTRATION (ug/L)IMPLIED BENZENE CONCENTRATIONESTIMATED EXTENT OF BENZENE AT CONCENTRATIONSEXCEEDING NC 2L GROUNDWATER STANDARDNOTE: 1.) 2019 AERIAL OBTAINED FROM NC ONE MAP.(5.23)1.0KBB
MJ
DRAWN BY:
06/12/2023 23-0307-AL
5
SCALE:FIGURE NO.:
PROJECT NO.:DATE:APPROVED BY:
CARY CERAMICS SUPPLYINCIDENT # 3530
2166 (2186) NORTH SALEM STREETAPEX, WAKE COUNTY, NC
GROUNDWATER BENZENE
ISOCONCENTRATION MAP (ug/L)JUNE 2023
WithersRavenel
Engineers | Planners | Surveyors
115 MacKenan Drive | Cary, NC 27511 | t: 919.469.3340 | license #: F-1479 | www.withersravenel.com
1"=40 'GRAPHIC SCALE1 inch = 40 ft.0402080