HomeMy WebLinkAboutWS-3748_12330_CA_RPTS_20170110_letter report
January 10, 2017
Mr. Herb Berger NCDEQ, Division of Waste Management, UST Section 1646 Mail Service Center
Raleigh, North Carolina 27699-1646 RE: Letter Report – Kodell’s Grocery
NC Highway 89 Westfield, Stokes County, North Carolina
NCDEQ Incident No.: 12330
NCDEQ Contract No. N14007i ECS Project No. 49-3394
Dear Mr. Berger:
As authorized by your acceptance of ECS Carolinas, LLP’s (ECS) Task Authorization Request
No. 4 dated November 1, 2016 and approved on November 4, 2016, ECS has prepared a Letter Report for the above referenced site. This report includes a description of the work performed,
the results obtained, and our conclusions and recommendations. PROJECT UNDERSTANDING The subject site, Kodell’s Grocery, is located off of NC Highway 89 across the street from Francisco Elementary School in Westfield, Stokes County, North Carolina (Figures 1 and 2).
Based on information provided to ECS, three 1,000-gallon gasoline underground storage tanks (USTs) and one 555-gallon kerosene UST were removed from the site in January 1994.
Samples collected after the USTs were removed indicated impact by Total Petroleum
Hydrocarbons Gasoline Range Organics (TPH GRO) beneath the gasoline and kerosene tanks. Four monitoring wells (MW-1, MW-2, MW-3, and MW-4) were installed and sampled in 2010.
Since 2010, the monitoring wells have been sampled twice, in 2012 and most recently in 2014. Laboratory analysis of the samples detected compounds above their respective North Carolina
2L Ground Water Quality Standards (NC2LGWQS) in samples collected from monitoring wells
MW-1 and MW-3. Based on water table elevation data, the groundwater is flowing to the north-northwest. The horizontal extent of contamination has been determined.
Receptor surveys have determined that nine water-supply wells are located within 1,000 feet of the site and determined public water is not available in the vicinity of the site. The four wells
locate within 500 feet of the release (WSW-0460, WSW-9974, WSW-1737, and WSW-2242) have been sampled three times. The laboratory analysis has not detected hydrocarbons associated with the petroleum release; however, trihalomethanes, associated with chlorination,
have been detected in the water well located behind (south) of the school. It is ECS’s opinion that the trihalomethanes are a result of disinfecting the well with chlorine.
Letter Report – Kodell’s Grocery NCDEQ Incident No. TF-12330 Westfield, Stokes County, North Carolina
ECS Project No. 49-3394 January 10, 2017
2
On February 9, 2015, personnel from ECS mobilized to the site to install, survey and sample one additional Type II groundwater monitoring well (MW-5) on the north downgradient side of the site. Laboratory analysis detected benzene, ethylbenzene, naphthalene, styrene, toluene, 1,2,4-trimethylbenzene, and total xylenes at concentrations exceeding their NC 2L Groundwater Standards (NC2LGWQS) in MW-5. 1,3,5-Trimethylbenzene and n-propylbenzene were detected above the laboratory method detection limit but below their NC2LGWQSs. The concentrations do not exceed the Gross Contamination Levels (GCLs). Based on the laboratory analytical results, the horizontal extent of the groundwater contamination has not been defined. ECS recommended installing two monitoring wells downgradient of MW-5 to further define the extent of contamination. Following installation of the wells, the two new wells and MW-1, MW-3, and MW-5 should be sampled.
In October 2015, ECS observed and documented the installation and subsequent surveying and
sampling of two monitoring wells (MW-6 and MW-7) at the site (Groundwater Monitoring Report,
ECS Project 09-25088A, report dated November 4, 2015). Additionally, monitoring wells MW-1, MW-3, and MW-5 were sampled. The Groundwater Monitoring Report summarized, concluded,
and recommended the following:
• ECS sampled five Type II monitoring wells.
• The groundwater flow direction is generally to the northwest across the site;
• Monitoring well MW-1 concentrations of toluene, ethylbenzene, total xylenes, styrene, naphthalene, isopropyl benzene, n-Propylbenzene, 1,2,4-trimethylbenzene, and 1,3,5-
trimethylbenzene were detected above their respective NC2LGWQS, but below their GCLs;
• Monitoring well MW-3 and MW-5 concentrations of benzene, toluene, ethylbenzene, total xylenes, styrene, naphthalene, isopropyl benzene, 1,2,4-trimethylbenzene, and 1,3,5-
trimethylbenzene.
• No free product was detected in the monitoring wells;
• The concentrations of petroleum related hydrocarbons generally increased in each well sampled since the 2014 sampling events.
• Laboratory analysis of groundwater samples collected from monitoring wells MW-6 and MW-7 did not detect targeted compounds above the laboratory reporting limits.
• Based on the results of the recent investigation, it is ECS’ opinion that the plume has been adequately delineated.
• ECS recommended installing O-sox in MW-1, MW-3 and MW-5 and sampling the wells in six months.
On November 4, 2016, the NCDEQ approved sampling MW-1, MW-3, and MW-5.
GROUNDWATER ASSESSMENT
Groundwater Flow Measurements
On November 22, 2016, ECS measured the static water level (SWL) in three monitoring wells using a decontaminated electronic water level meter. The static water levels and top of casing
elevations were used to calculate groundwater flow direction. The static water level
measurements can be found on Table 1.
Letter Report – Kodell’s Grocery NCDEQ Incident No. TF-12330 Westfield, Stokes County, North Carolina
ECS Project No. 49-3394 January 10, 2017
3
Monitoring Well Sampling
On November 22, 2016, ECS personnel collected samples from three monitoring wells (MW-1,
MW-3, and MW-5). The locations of the wells are shown on Figure 3. Prior to sampling, the wells were purged using a new disposable polyethylene bailer and new length of nylon cord. The wells
were developed/purged by evacuating a minimum of three well volumes using the bailer and cord.
The wells were developed/purged to remove sand, silt and other fine sediments and to promote communication between the surrounding formation and the sand pack surrounding the well’s
screened interval. After purging was completed, the sampler wearing a new pair of disposable nitrile gloves for each sampling point poured the groundwater sample from the bailer into laboratory prepared containers. Each container was labeled and placed in a cooler containing ice to maintain
the samples at approximately 4° Celsius. The sample containers were then delivered to Pace Analytical Services, Inc. (Pace) in Huntersville, North Carolina to be analyzed for volatile organic
compounds (VOCs) using Standard Method 6200B plus methyl tert butyl ether (MTBE), isopropyl
ether (IPE), and ethylene dibromide (EDB). A Chain of Custody Record was maintained and is attached.
Groundwater Chemistry
Prior to collecting the groundwater samples, geochemical parameters (temperature, pH, dissolved
oxygen, and conductivity) were measured using a YSI Model 560 meter. The turbidity was observed during the sampling and recorded on the Groundwater Sampling Data Sheets which are
attached. RESULTS
Groundwater Flow Direction
The groundwater flow direction is generally to the northwest across the site (Figure 4). Groundwater at the site is flowing to the northwest under a gradient of 0.0181 ft/ft as determined
between MW-1 and MW-6. Monitoring Well Sampling Results
Laboratory analysis of groundwater samples collected from monitoring wells MW-1, MW-3, and MW-5 detected targeted compounds that exceed their respective NC2LGWQS; however, the
concentrations did not exceed their respective GCLs. A summary of the current and historical groundwater analytical results are included in Table 2. The laboratory data sheets are attached.
Using the laboratory analytical results of the groundwater samples collected from the groundwater monitoring wells, isoconcentration maps showing the horizontal extent of benzene, ethylbenzene, toluene, xylenes, and naphthalene are included as figures.
Letter Report – Kodell’s Grocery NCDEQ Incident No. TF-12330 Westfield, Stokes County, North Carolina
ECS Project No. 49-3394 January 10, 2017
4
CONCLUSIONS
ECS has completed the groundwater monitoring sampling at the site. ECS sampled three Type II
monitoring wells. Based on on-site groundwater measurements and laboratory analytical results, ECS concludes the following:
• The groundwater flow direction is generally to the northwest across the site;
• Monitoring well MW-1 concentrations of toluene, total xylenes, naphthalene, n-
propylbenzene, and 1,2,4-trimethylbenzene were detected above their respective
NC2LGWQS, but below their GCLs;
• Monitoring well MW-3 concentrations of benzene, toluene, ethylbenzene, total xylenes,
styrene, naphthalene, isopropyl benzene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene were detected above their respective NC2LGWQS, but below their GCLs;
• Monitoring well MW-3 concentrations of benzene, toluene, ethylbenzene, total xylenes,
styrene, naphthalene, 1,2,4-trimethylbenzene, and 1,3,5-trimethylbenzene were detected
above their respective NC2LGWQS, but below their GCLs;
• No free product was detected in the monitoring wells;
• The concentrations of petroleum related hydrocarbons have generally decreased in MW-1, stayed the same in MW-3, and increased in MW-5 since the 2015 sampling events.
• Based on the results of the recent investigation, it is ECS’ opinion that the plume has been adequately delineated.
RECOMMENDATIONS
ECS recommends that a copy of this report be sent to the property owner and that an O-sox or
similar be installed in MW-1, MW-3 and MW-5 and sampling the wells in six months.
SOURCE:
USGS TOPOGRAPHIC MAP
STEWART SE, DATE 1968 REVISED 1938; HANGING
ROCK, DATED 1964 REVISED 1977; PILOT MOUNTAIN, DATE 1964 REVISED 1977, CLAUDVILLE, DATED 1968 REVISED 1977;NC
QUADRANGLES
FIGURE 1
SITE LOCATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SITE
APPROXIMATE SITE BOUNDARY
SCALE (IN FEET)
2,000 1,000 0 2,000
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 2 AERIAL SITE LOCATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
APPROXIMATE SITE BOUNDARY
SCALE (IN FEET)
140 70 0 140
MW-3 MW-1
MW-4
MW-2
MW-6
MW-7
MW-5
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 3 MONITORING WELL LOCATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
LEGEND
MONITORING WELL LOCATION
FORMER UST LOCATION
MW-3
73.16 MW-1 74.27
MW-4 NM
MW-2 NM
MW-6
NM
MW-7
NM
MW-5 72.6
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 4 GROUNDWATER FLOW DIRECTION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
70
72
73
MW-3
(260) MW-1
<0.5
MW-4
NS
MW-2
NS
MW-6
NS
MW-7
NS
MW-5
(81)
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 5 BENZENE ISOCONCENTRATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
<0.5
200
Explanation:
NS = Not Sampled
(171) = Concentration in ppb
MW-3
27,000 MW-1
140
MW-4
NS
MW-2
NS
MW-6
NS
MW-7
NS
MW-5
15,000
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 5A TOLUENE ISOCONCENTRATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
<0.5
10,000
Explanation:
NS = Not Sampled
(171) = Concentration in ppb
MW-3
2,800 MW-1
260
MW-4
NS
MW-2
NS
MW-6
NS
MW-7
NS
MW-5
1,800
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 5B ETHYLBENZENE ISOCONCENTRATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
<0.5
1,000
Explanation:
NS = Not Sampled
(171) = Concentration in ppb
MW-3
14,000
MW-1
1,700
MW-4
NS
MW-2
NS
MW-6
NS
MW-7
NS
MW-5
9,400
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 5C TOTAL XYLENES ISOCONCENTRATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
<0.5
5,000
Explanation:
NS = Not Sampled
(171) = Concentration in ppb
MW-3
490
MW-1 89
MW-4
NS
MW-2
NS
MW-6
NS
MW-7
NS
MW-5
300
SOURCE:
STOKES COUNTY GIS DEPARTMENT
AERIAL PHOTOGRAPH, DATED 2010
FIGURE 5D NAPTHALENE ISOCONCENTRATION MAP
KODELL’S GROCERY
NC HIGHWAY 89
WESTFIELD, STOKES COUNTY, NORTH
CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT NO. 49-3394
SCALE (IN FEET)
47 23.5 0 47
Kodell’s
Grocery
Residence
School
Driveway
<0.5
300
Explanation:
NS = Not Sampled
(171) = Concentration in ppb
WELL ID #
DATE
WATER
LEVEL
MEASURED
TOP OF
CASING
ELEVATION
(ft.)
APPROXIMATE
CONSTRUCTED
WELL DEPTH
(ft.)
SCREENED
INTERVAL (ft
BLS)
DEPTH TO
WATER
FROM TOP
OF CASING
(ft.)
MEASURED
GROUNDWATER
ELEVATION (ft.)
6/14/2010 24.46 75.54
2/24/2012 25.79 74.21
6/7/2012 25.22 74.78
1/8/2013 26.43 73.57
9/19/2014 24.9 75.1
10/16/2015 26.45 73.55
11/22/2016 25.73 74.27
6/14/2010 24.7 76.32
2/24/2012 26.18 74.84
6/7/2012 27.86 73.16
1/8/2013 26.84 74.18
9/19/2014 25.35 75.67
6/14/2010 23.69 74.29
2/24/2012 24.8 73.18
6/7/2012 24.31 73.67
1/8/2013 25.37 72.61
9/19/2014 24.1 73.88
10/16/2015 25.4 72.58
11/22/2016 24.82 73.16
6/14/2010 21.38 74.5
2/24/2012 22.52 73.36
6/7/2012 21.97 73.91
1/8/2013 23.18 72.7
9/19/2014 21.6 74.28
2/9/2015 22.69 73.06
10/16/2015 23.68 72.07
11/22/2016 23.15 72.6
MW-6 10/16/2015 84.86 25 10-25 14.0 70.86
MW-7 10/16/2015 85.50 22 12-22 15.1 70.4
Elevations measured to an assumed datum of 100 feet.
MW-5 95.75 32 17-32
40 20-40
MW-3 97.98 35 15-35
Monitoring Well data and top of casing elevations for MW-1, MW-2, MW-3, and MW-4 was collected
from Phase II LSA conducted by Agra Environmental in 2010.
TABLE 1: SUMMARY OF MONITORING WELL DATA
KODELL'S GROCERY
WESTFIELD, STOKES COUNTY, NORTH CAROLINA
NCDEQ INCIDENT No. 12330
ECS PROJECT 49-3394
15-35
MW-1 100
15-3535
35
MW-4
MW-2
95.88
101.02
KODELL'S GROCERY
WESTFIELD, STOKES COUNTY, NORTH CAROLINA
NCDEQ INCIDENT No.12330
ECS PROJECT 49-3394
Sample Identification MW-6 MW-7
Sample Date 03/04/10 06/14/10 02/24/12 06/07/12 01/08/13 09/19/14 10/16/15 11/20/16 06/14/10 02/24/12 06/07/12 01/08/13 09/19/14 06/14/10 02/24/12 06/07/12 01/08/13 09/19/14 10/16/15 11/20/16 06/14/10 02/24/12 06/07/12 01/08/13 09/19/14 02/09/15 10/16/15 11/20/16 10/16/2015 10/16/2015
Analysis
Benzene <4.0 <5.4 ND 22 4.5 <0.5 <0.5 <0.5 ND ND ND ND <0.5 1,600 1,800 2,000 802 460 479 260 ND ND ND ND <0.5 38 171 81 <0.5 <0.5 1 5,000
Toluene 3,900 2,500 6,200 4,100 3,200 435 1,590 140 ND ND ND ND <0.5 26,000 40,000 46,000 22,600 21,600 27,400 27,000 ND ND ND ND <0.5 5,600 13,200 15,000 <0.5 <0.5 600 260,000
Ethylbenzene 6,200 3,700 2,200 1900 1,190 280 749 260 ND ND ND ND <0.5 1,600 2,600 28,00 2,060 2,040 2,450 2,800 ND ND ND ND <0.5 830 1,230 1,800 <0.5 <0.5 600 84,500
Total Xylenes 30,000 18,500 9,100 7,400 5,460 1,540 3,880 1,700 ND ND ND ND <1 9,100 13,000 15,000 10,840 9,490 12,610 14,000 ND ND ND ND <1 4,000 6,500 9,400 <1 <1 500 85,500
Methyl Tertbutyl Ether ND 79J ND ND 3.3 <0.5 <0.5 <0.5 ND ND ND ND <0.5 ND ND ND 2.9 <0.5 <0.5 <0.5 ND ND ND ND <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 20 20,000
Isopropyl Ether NA NA NA ND ND <0.5 <0.5 <0.5 NA NA ND ND <0.5 NA NA 13 13 <0.5 <0.5 <0.5 NA NA ND ND <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 70 70,000
Styrene 440 210 210 110 ND 19.7 70.9 19 ND ND ND ND <0.5 300 430 560 ND 360 373 500 ND ND ND ND <0.5 104 181 350 <0.5 <0.5 70 70,000
Acetone NA NA NA ND ND <25 <0.5 14 NA NA ND ND <0.5 NA NA 100 ND <0.5 <0.5 <0.5 NA NA ND ND <0.5 <25 <0.5 <0.5 <0.5 <25 6 6M
Naphthalene NA NA NA 550 472 83.7 208 89 NA NA ND ND <0.5 NA NA 400 371J 265 428 490 NA NA ND ND <0.5 100 245 300 <0.5 <0.5 6 6,000
n-Butylbenzene 84J 54 61 46 ND 8.1 <0.5 <0.5 ND ND ND ND <0.5 ND 20 15 ND <0.5 <0.5 <0.5 ND ND ND ND <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 70 6,900
sec-Butylbenzene 51 ND 49J 26 ND 6.8 <0.5 13 ND ND ND ND <0.5 ND 17 7.5 ND <0.5 <0.5 <0.5 ND ND ND ND <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 70 8,500
Isopropyl Benzene 380 280 190 180 139 31.8 71.2 48 ND ND ND ND <0.5 41 70 71 70.6 46.8 <0.5 81 ND ND ND ND <0.5 <0.5 39.9 56 <0.5 <0.5 70 25,000
p-Isopropyltoluene NA NA NA 30 ND 12.5 <0.5 <0.5 NA NA ND ND <0.5 NA NA 12 ND <0.5 <0.5 <0.5 NA NA ND ND <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 25 1,700
n-Propylbenzene 1,200 820 520 540 369 107 217 160 ND ND ND ND <0.5 120 170 200 192 135 199 220 ND ND ND ND <0.5 69.5 103 150 <0.5 <0.5 70 30,000
1,2,4-Trimethylbenzene 9,500 5,700 3,400 2,400 2,310 522 1,260 810 ND ND ND ND <0.5 1,100 6.7 1,300 1,340 987 1,410 1,700 ND ND ND ND <0.5 488 777 940 <0.5 <0.5 400 28,500
1,3,5-Trimethylbenzene 2,600 1,700 1,000 1,000 2,490 188 440 300 ND ND ND ND <0.5 330 390 510 1,260 299 452 520 ND ND ND ND <0.5 149 <0.5 270 <0.5 <0.5 400 25,000
Notes:
NC2LGWQS = North Carolina 2L Groundwater Quality Standard
GCL = Gross Contamination Level
ND = Not Detected Above the Laboratory Method Detection Limit
NA = Not Analyzed for This Compound
Results presented in µg/l = micrograms per liter = ppb (parts per billion)
J-Value = Estimated value between laboratory reporting limit and method detection limit
BOLD = Concentration Exceeds NC2LGWQS
6200B
BOLD = Concentration Exceeds NC2LGWQS
MW-2 MW-4MW-1 MW-3 MW-5
TABLE 2: SUMMARY OF GROUNDWATER ANALYTICAL RESULTS (MONITORING WELLS)
NC2LGWQS GCL
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