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TABLE OF CONTENTS
1 SITE IDENTIFICATION......................................................................................... 1
2 SITE HISTORY......................................................................................................... 2
3 GROUNDWATER MONITORING........................................................................ 3
3.1 Monitor Well Sampling...................................................................................... 3
3.2 Monitor Well Sampling Results.......................................................................... 3
4 CONCLUSIONS AND RECOMMENDATIONS .................................................. 4
FIGURES
1 Site Location Map
2 Site Aerial Map
3 Potentiometic Map
4 Groundwater Quality Map
TABLES
1 Monitor Well Construction and Groundwater Level Data
2 Summary of Water Sampling Results
APPENDICES
I Laboratory Analytical Report and Chain of Custody Form
II Field Sampling Forms
III Site Photos
Groundwater Monitoring Report – NCDENR Incident No. 32107 S&ME Project No. 1354-09-103B
Norris Luv Station, Chinquapin, Duplin County NC July 20, 2010
2 SITE HISTORY
The site is located at the southeast intersection of Hwy 41 South and Oak Street in
Chinquapin, Duplin County, North Carolina. Two 10,000-gallon gasoline USTs, two
2,000-gallon USTs and one 2,000-gallon diesel UST were removed in March 1993. A
petroleum release was discovered associated with the two 10,000-gallon gasoline USTs.
The use of the surrounding area is mostly farmland and residential. Figure 1 indicates
the site location and topography. The land elevation of the site is between 10 and 15 feet
above mean sea level, and the topography suggests a southerly groundwater flow beneath
the site. Currently the site building is used sporadically as a maintenance garage. There is
a large propane tank in the southern portion of the property. The site aerial is depicted on
Figure 2.
In November 2003, MACTEC collected soil samples beneath the two 10,000-gallon
gasoline USTs to fulfill the UST Closure sampling requirement. Petroleum contaminants
(benzene, ethylbenzene and xylenes) were detected at concentrations exceeding the
Maximum Soil Contaminant Concentrations. Those results were reported in a November
25, 2003 Letter Report of Limited Soil Assessment.
Subsequently, MACTEC prepared a Report of Phase II Limited Site Assessment, dated
October 15, 2004. The findings of the Limited Site Assessment are listed below:
1. Four shallow monitor wells (MW-1, 3, 4, and 5) and one deep monitor well (MW-
2) were installed at the site.
2. Dissolved petroleum hydrocarbons in the groundwater were detected at
concentrations exceeding the 15A NCAC 2L groundwater quality standards (2L
Standards): Benzene as high as 190 micrograms per liter or µg/L (MW-1); C5-C8
Aliphatics as high as 1,600 µg/L (MW-1); and C9-C10 Aromatics as high as 520
µg/L (MW-1).
3. One of three municipal water supply wells for the Chinquapin Water Association
(CWA) is located approximately 700 feet west-northwest of the site (Figure 1).
This well is reportedly 330 feet deep with the upper screen section at a depth
interval of 295 to 300 feet below land surface. No other active drinking water
supply wells were identified within 1,500 feet of the site. One inactive irrigation
well is located within 250 feet to the west.
4. A Class C Surface Water body (a tributary of the North Cape Fear River) with a
High Quality Water designation is located approximately 400 feet south of the
site.
In June 2008, Withers & Ravenel (W&R) sampled the site monitor wells and the results
indicated lower concentrations than detected in 2004. Benzene in MW-1 (4.4 µg/L) was
the only contaminant detected above the 2L Standards, although the Aliphatics and
Aromatics were not included in the analyses. The results were included in a June 23,
2008 Monitoring Report.
2
Groundwater Monitoring Report – NCDENR Incident No. 32107 S&ME Project No. 1354-09-103B
Norris Luv Station, Chinquapin, Duplin County NC July 20, 2010
In July 2009, S&ME sampled the site monitor wells and the results indicated monitor
wells MW-1, MW-2 and MW-4 contained several petroleum contaminants. No
contaminants were detected in monitor well MW-3. Benzene in MW-1 (4.6 µg/L) and
MW-4 (28 µg/L) and tetrachloroethene in MW-4 (1.2 µg/L) were detected at
concentrations exceeding the 2L Standards of 1 and 0.7 µg/L, respectively.
In December 2009, S&ME sampled the site monitor wells and the results indicated
monitor wells MW-1, MW-2 and MW-4 contained several petroleum contaminants. No
contaminants were detected in monitor well MW-3. Benzene, methyl tert butyl ether
(MTBE), and naphthalene in MW-1 and MW-4 were above the 2L Standard.
Tetrachloroethene was not detected in MW-4 during this sampling event.
3 GROUNDWATER MONITORING
S&ME, Inc. (S&ME) submits this Groundwater Monitoring Report for the above
referenced site. The report was prepared in general accordance with the 15A NCAC 2L
.0115 regulations and the North Carolina Department of Environment and Natural
Resources (NCDENR, Contract # 16-1713-3C for the Eastern Region, and S&ME’s
Proposal Number 1354-22639-10 dated February 17, 2010 as approved with NCDENR’s
Task Authorization #3 dated February 23, 2010.
The approved scope of services for this monitoring report included the following (with
excluded work in parentheses):
1. Sample four monitor wells: MW-1, 2, 3, and 4.
2. Report the results of the sampling with conclusions and recommendations.
3.1 Monitor Well Sampling
On June 7, 2010, S&ME visited the site to perform the approved services. S&ME
measured the depth to water in the monitor wells and sampled the wells. The depth to
water ranged from 3.58 feet below top of casing (ft-TOC) in MW-3 to 5.80 ft-TOC in
MW-2 (Table 1). Water levels dropped as much as 3.14 feet (MW-1) since the previous
sampling event on December 8, 2009. Based on the top of casing elevations and depth to
water, groundwater flow is to the southeast (Figure 3).
After measuring the depth-to-liquid, S&ME personnel purged each well with a new
disposable polyethylene bailer by evacuating three well volumes, or until the well was
dry. After completing the well purging and allowing groundwater to recover in the
monitor well, S&ME personnel collected a groundwater sample from the monitor wells.
The groundwater samples were placed in laboratory-supplied containers, stored in a
cooler with ice, and shipped under chain-of-custody procedures to Prism Laboratories,
Inc. (Prism), a North Carolina certified laboratory for laboratory analysis. The
groundwater sample was analyzed for VOCs by EPA Method 6200B.
3.2 Monitor Well Sampling Results
The laboratory analytical results are summarized in Table 2 and a copy of the laboratory
report and chain-of-custody form is included in Appendix II.
3
Groundwater Monitoring Report – NCDENR Incident No. 32107 S&ME Project No. 1354-09-103B
Norris Luv Station, Chinquapin, Duplin County NC July 20, 2010
Monitor wells MW-1, MW-2, and MW-4 contained several petroleum contaminants.
Benzene in MW-1 (39 micrograms per liter or µg/L) and MW-4 (170 µg/L), MTBE in
MW-1 (26 µg/L) and MW-4 (24 µg/L) and naphthalene in MW-1 (22 µg/L) in MW-4 (17
µg/L) were detected at concentrations exceeding the 2L Standards of 1, 20 and 6 µg/L,
respectively. Tetrachloroethene was not detected during the July 2010 sampling event.
Compared to the April 2004 sampling results, contaminant concentrations decreased in
MW-3, increased slightly in MW-2 (but below 2 L Standards), increased in MW-4 and
fluctuated in MW-1. The increased concentrations in MW-1 since December 2009 may
be due to dropping groundwater elevations since the concentrations from the July 2009
event were generally similar to the concentrations from this sampling event. It is possible
that the increased concentrations in MW-4 may be due to the migration of the plume
towards MW-4 (downgradient) since concentrations have been steadily increasing over
time. The types and concentrations of contaminants in MW-1 and MW-4 do not indicate
a separate source for the contaminants in MW-4, although this cannot be discounted.
Contaminant concentrations exceeding the 2L standard are illustrated on Figure 4.
4 CONCLUSIONS AND RECOMMENDATIONS
A groundwater monitoring event was conducted at the Norris Luv Station UST site at the
intersection of NC Hwy 41 and Oak Street in Chinquapin, Duplin County, North Carolina
to assess current petroleum impact to groundwater.
The findings at the site are as follows:
• Municipal water is available to the area with the source derived from three water
supply wells, one of which is located ~ 700 feet west-northwest of the site. There
is also an inactive irrigation well located within 250 feet of the site. Replacement
of the municipal water supply well is not likely a feasible method to reduce the
risk of the UST incident from high.
• A High Quality Water tributary is located within 500 feet of the site to the south.
Contaminant concentrations at the site do not exceed the surface water quality
standards by more than ten times.
• The depth to water ranged from 3.58 to 5.80 feet below the flush-mounted top of
well casings. Groundwater flow appears to be to the southeast.
• Concentrations of Benzene, MTBE and naphthalene in MW-1 and MW-4 exceed
the 2L groundwater quality standards.
• Historically, contaminant concentrations have increased in MW-4 and have
fluctuated in MW-1. The increased concentrations in MW-4 may be due to plume
migration towards MW-4 since concentrations in MW-4 (downgradient) have
been steadily increasing over time.
Based on the above, S&ME recommends the following action to be conducted:
December 2010
1. Due to increasing levels of contaminants in MW-4, install 3 additional shallow
monitor wells (MW-6, 7 and 8) at the locations indicated on Figure 3.
4
Groundwater Monitoring Report – NCDENR Incident No. 32107 S&ME Project No. 1354-09-103B
Norris Luv Station, Chinquapin, Duplin County NC July 20, 2010
5
2. Continue monitored natural attenuation with semi-annual sampling of all monitor
wells.
Consider future use of one of the following options with the goal of reducing the
contaminants concentrations to below the 2L Standard in order to pursue site closure:
1. Inject an oxidizing agent in the subsurface.
2. Install six 1-inch sparge wells and perform 8-hour sparging events.
FIGURES
Approximate Location of Subject Property
Approximate Water Supply Well Location
Circles are 250, 500, 1000 and 1500 feet radii
Scale: As Shown
Checked by: MNM
Drawn by: WAQ
Date: 7-13-2010
SITE LOCATION MAP
Norris Luv Station Incident # 32107
NC Highway 41 South
Chinquapin, North Carolina
Figure
1
S&ME Job No.: 1354-09-103B
1 in ~ 1,200 ft
Source: 1991 USGS Topographic Map obtained from http://terraserver-usa.com
Inactive
Irrigation
Well
Chinquapin
Municipal Water
Supply Well
LEGEND
Property Boundary of Site
Approximate Monitor Well Location
Scale: 1 in ~ 60 ft
Checked by: WAQ
Drawn by: KRK
Date: 7-13-2010
SITE AERIAL PHOTOGRAPH
Norris Luv Station, Inc.# 32107
NC Highway 41 South
Chinquapin, North Carolina
Figure
2
S&ME Job No.: 1354-09-103B
Norris Luv
Station
Source: 2006 Aerial Photograph Obtained from Duplin County GIS Website
MW-4
MW-2
MW-3Pump
Island
~ Former
UST Basin
MW-1
MW-5
Destroyed
~ Former
Dispensing Island
1 in ~ 60 ft
LEGEND
Approximate Monitor Well Location
(PMW-#: Proposed)
Groundwater Elevation (June 7, 2010)
Scale: 1 in ~ 30 ft
Checked by: WAQ
Drawn by: KRK
Date: 7-13-2010
Potentiometric Map
Norris Luv Station, Inc.# 32107
NC Highway 41 South
Chinquapin, North Carolina
Figure
3
S&ME Job No.: 1354-09-103B
PMW-8
PMW-7
94.32
Destroyed
94.32
94.63
94.11
96.46 96.0
PMW-6
94.5
95.0
95.5
1 in ~ 30 ft
Source: MACTEC’s Report of Phase II Limited Site Assessment, dated October 15, 2004.
LEGEND
Approximate Monitor Well Location
Concentrations in µg/L, Sampled on June 7, 2010
Scale: 1 in ~ 30 ft
Checked by: MNM
Drawn by: WAQ
Date: 7-13-2010
Groundwater Quality Map
Norris Luv Station, Inc.# 32107
NC Highway 41 South
Chinquapin, North Carolina
Figure
4
S&ME Job No.: 1354-09-103B
MW-1
Benzene 170
Naphthalene 17
MTBE 24
Destroyed
MW-1
Benzene 39
Naphthalene 22
MTBE 26
None > 2L
None > 2L
1 in ~ 30 ft
Source: MACTEC’s Report of Phase II Limited Site Assessment, dated October 15, 2004.
TABLES
Table 1Monitor Well Construction and Groundwater Level DataNorris Luv Station, Incident #32107NC Hwy 41 SouthChinquapin, Duplin County, North CarolinaS&ME Project No. 1354-09-103BWell IDDateInstalled(m/dd/yy)DateWaterLevelMeasured(m/dd/yy)WellCasingDiameter(in)WellCasingDepth(ft. BGS)Depthof Well Previously Reported(ft. BGS)Top ofCasingElevation*(ft.)Depth toWaterfrom Top of Casing(ft.)GroundwaterElevation*(ft.)07/29/09 2 3.0 3 - 13 13 99.85 4.84 95.0112/08/09 2 3.0 3 - 13 13 99.85 2.08 97.7706/07/10 2 3.0 3 - 13 13 99.85 5.22 94.6307/29/09 2 17.0 22 - 27 27 99.91 5.59 94.3212/08/09 2 17.0 22 - 27 27 99.91 3.98 95.9306/07/10 2 17.0 22 - 27 27 99.91 5.80 94.1107/29/09 2 3.0 3 - 13 13 100.04 1.38 98.6612/08/09 2 3.0 3 - 13 13 100.04 1.26 98.7806/07/10 2 3.0 3 - 13 13 100.04 3.58 96.4607/29/09 2 3.0 3 - 13 13 100.04 5.28 94.7612/08/09 2 3.0 3 - 13 13 100.04 3.52 96.5206/07/10 2 3.0 3 - 13 13 100.04 5.72 94.32MW-5Unknown 07/29/09 2 3.0 3 - 13 13 99.71 NM NA* Reference Point for Elevation Measurements: Temporary Site DatumAssumed Elevation: 100.00 ft.** If Free Product is present in a well, groundwater elevation should be calculated by: [Top of Casing Elevation - Depth to Water] + [free product thickness x 0.8581]NA = Not Applicable Screen depths and intervals assumed based on 10-foot screen lengths to the total well depthft BGS = feet below ground surfaceNM = Not measuredDepths of wells as constructed and top of casing elevations reported per previous site workDestroyedMW-1MW-2MW-3MW-4UnknownUnknownUnknownUnknownScreenInterval(x to y ft. BGS)Comments
Table 2 Summary of Water Sampling ResultsNorris Luv Station, Incident #32107NC Hwy 41 SouthChinquapin, Duplin County, North CarolinaS&ME Project No. 1354-09-103BAnalytical Method Contaminant Well IDDateCollected(mm/dd/yy) Ethylbenzene Methyl Tert Butyl Ether n-Butylbenzene tert-Butylbenzene Di-isopropyl ether Isopropyl benzene 4-Methyl-2-pentanone Naphthalene n-Propylbenzene p-Isopropyltoluene sec-Butylbenzene Tetrachloroethene04/13/04ND 190ND50 285.2 75ND ND14 10ND ND23ND ND ND110 3106/04/08ND 4.4ND ND ND8.1ND ND5.1 1.2ND ND2.2ND ND ND2.3 1.107/29/09 <504.6<57.5 180 29 8.9 1.4 48 13<1015 27<5 <5 <193 1512/08/09 <540 1.5 1.1 15.3 2.9<1 <0.53.9 1.6<50.90J 2.7<1 <1 <12.7 0.7306/07/10 <1039 3.7 13 352 26 2.2<0.549 19<0.522 35 0.93 1.9<0.5130 2509/01/04 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND06/04/08 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND07/29/09 <50 <1 <5 <1 <29.5<1 <11.6<1 <10 <5 <1 <1 <1 <1 <1 <112/08/09 <5 <0.5 <0.5 <0.5 <0.56.7<1 <0.51.4<0.5 <5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.506/07/10 <5 <0.5 <0.5 <0.5 <0.55.3<0.5 <0.51.2<0.5 <5 <1 <0.5 <0.5 <0.5 <0.5 <0.5 <0.509/01/04 ND ND ND26 200ND ND ND ND ND ND ND12ND ND ND81 2306/04/08 ND ND ND1.3ND ND ND ND ND ND ND ND1ND ND ND ND ND07/29/09 <50 <1 <5 <1 <2 <1 <1 <1 <1 <1 <10 <5 <1 <1 <1 <1 <1 <112/08/09 <5 <0.5 <0.5 <0.5 <0.5 <0.5 <1 <0.5 <0.5 <0.5 <5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.506/07/10 <10 <0.5 <0.5 <0.5 <0.5 <0.5 <1 <0.5 <0.5 <0.5 <5 <2 <0.5 <0.5 <0.5 <0.5 <0.5 <0.509/01/04 ND7.2ND ND ND2.6ND ND1ND ND ND ND ND ND ND ND ND06/04/08 ND ND ND6ND ND ND ND ND1.4ND ND4.1ND ND ND4.4ND07/29/09 <5028<54.1 3.8 21<1 <120 7<106.3 7.9<1 <11.2 1.6<112/08/09340 130 5.9 9.6 15.3 50<1 <0.543 5.7<56.2 7.7<0.5 <0.51.3 1.6 0.5606/07/1011 170 5.9 20 52.4 24 0.96<0.525 14<0.517 17<0.51.3<0.517 42L Standard6,000 1 600 600 500 20 70 70 70 70 NL 6 70 NL 70 0.70 400 4002B Standard2,000 61 11 97 670 690 4 --- 13,000 320 26,000 330 --- --- --- 3.30 390 630GCL6,000,000 5,000 260,000 84,500 85,500 20,000 6,900 15,000 70,000 25,000 NL 6,000 30,000 NL 8,500 700 28,500 25,000Notes:All values reported in micrograms per liter (µg/l)2L Standard = 15A NCAC 2L .0202 Groundwater Quality StandardGCL = Gross Contamination LevelValueExceeds the 2L Standard2B Standard = Surface Water Quality Standard, Lower of the Human Health, Freshwater Aquatic Life, or High Quality Water standardsNL = No Listed GCL(---: No Standard Established)MW-4 1,3,5-Trimethylbenzene 1,2,4-Trimethylbenzene Toluene Xylenes (total) BenzeneEPA Method 6200BMW-1MW-2MW-3Acetone
APPENDIX I
LABORATORY REPORT AND CHAIN-OF-CUSTODY FORM
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APPENDIX II
FIELD SAMPLING FORMS
APPENDIX III
SITE PHOTOS
Norris Luv station, Incident # 32107
NC Hwy 41 South, Chinquapin, NC
Project #: 1354-09-103B
Sheet 1 of 2 9751 Southern Pine Blvd.
Charlotte, NC 28273
Photo 1 Date: 7-6-10 Photographer. Paul Masten Location / Orientation Frontal view of Norris Luv station taken from NC 41/50
Remarks MW-1 and MW-2 are in the direction shown above
MW-1 (~45’) & MW-2 (~38’). Distance is from
corner of pump island
Norris Luv station, Incident # 32107
NC Hwy 41 South, Chinquapin, NC
Project #: 1354-09-103B
Sheet 2 of 2 9751 Southern Pine Blvd.
Charlotte, NC 28273
Photo 2 Date: 7-6-10 Photographer. Paul Masten Location / Orientation Side view of Norris Luv Station taken from NC HWY 41/50
Remarks Note service bays near MW-4
MW-3MW-4