HomeMy WebLinkAbout17047_REEP_GPR Survey Report_Continental - New Building_20171206
Via Email
December 6, 2017
NC DEQ – Brownfields Section
1646 Mail Service Center
Raleigh, NC 27699-1646
Attn: Mr. Bill Schmithorst, PG
Subject: GPR Survey Report
Undeveloped Parcel
1900 Continental Boulevard
Charlotte, North Carolina
Brownfields Project No. 17047-13-60, Project 1
H&H Job No. LRC-005
Dear Bill:
1.0 Introduction
Following up on our meeting on October 3, 2017 and your comments about the waste disposal
area, Hart & Hickman, PC (H&H) is pleased to present this report documenting results of recent
ground penetrating radar (GPR) survey activities completed in a suspected waste disposal area in
the southeastern portion of the property located at 1900 Continental Boulevard in Charlotte,
Mecklenburg County, North Carolina (Site). The Site consists of approximately 26 acres of
undeveloped wooded land located east of the developed former Continental Tire property. A Site
location map is provided as Figure 1.
Current redevelopment plans at the Site include construction of an approximately 360,000 square
foot (sq ft) industrial warehouse facility with associated paved access roads, parking and loading
areas, and stormwater structures. In preparation for redevelopment of the Site, H&H understands
that clearing and grading activities are scheduled and will be completed in accordance with an
Mr. Bill Schmithorst, PG
December 6, 2017
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approved North Carolina Department of Environmental Quality (DEQ) Brownfields Program
Environmental Management Plan (EMP).
During wetlands delineation Site reconnaissance activities conducted in September 2015, H&H
observed burned/melted rubber mixed with drums containing white material and burned/melted
rubber on the ground surface near the drums in the southeastern portion of the Site. Also, a layer
of unnatural black stained soil up to a few inches thick was observed widespread in the
southeastern portion of the Site. Review of high resolution historical aerial photographs
indicates that as early as 1970, an approximately 10,000 sq ft potential disposal area was present
in the general area of discarded material observed by H&H in 2015. The approximated area of
potential historical waste disposal based on review of the 1970 aerial image is depicted on
Figure 2, and a copy of the 1970 aerial photograph is provided in Appendix A.
H&H provided oversight during removal of mostly surface waste materials which included
removal of several buried drums from February 29, 2016 to March 10, 2016. During surface
water removal, buried drums mixed with surface waste and buried waste solids (black rubbery
and white solids potentially associated with tire manufacturing) were partially removed. One
drum remained in the sidewall prior to covering the waste excavation with plastic and some fill
soil. This area where deeper buried drums/waste were identified and partially removed is shown
on Figure 2.
To attempt to better understand the extent of buried waste in the above specific location, H&H
subcontracted for a GPR survey in the vicinity of the historical disposal area to obtain additional
information associated with the extent of a buried waste area in the southeastern portion of the
Site and to evaluate subsurface conditions for the presence of additional buried drums. A
summary of the GPR survey activities and results is provided in the following section.
Mr. Bill Schmithorst, PG
December 6, 2017
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2.0 Ground Penetrating Radar Survey Activities
On November 2, 2017, H&H teamed with Probe Utility Locating, LLC (PUL) to conduct GPR
survey activities to evaluate the potential presence of additional buried waste material in the
southeastern portion of the Site. Prior to conducting field activities, H&H and PUL cleared brush
and small diameter trees for nine (9) transects across the area of concern. PUL then utilized a
Sensors & Software® GPR cart equipped with a 250 megahertz (MHz) antenna to scan the
transects for subsurface anomalies consistent with buried debris or disturbed soil. During GPR
survey activities, H&H utilized a Trimble GeoXT global positioning system (GPS) instrument
capable of sub-meter accuracy to estimate the locations of the GPR transects, edges of disturbed
subsurface soil, and obvious high-density subsurface anomalies consistent with metallic objects.
PUL prepared a GPR Investigation Summary Report dated November 8, 2017 to document the
field activities and interpretation of the GPR data. A copy of the PUL GPR report is provided in
Appendix B.
Results of GPR survey activities identified anomalies consistent with fill material and
unnaturally disturbed soil in the area near the 2016 waste removal excavation. Based on GPR
survey results, it appears that this excavation was conducted near the southern edge of a larger
disposal area. H&H collected GPS data points at the interface of disturbed soil and undisturbed
soil based on interpretation of the geophysical data to estimate the perimeter of the possible
waste disposal area. GPR indicated disturbed soil consistent with reworking and backfilling
activities, which covered an approximate 1,400 sq ft area. This appears to be generally consistent
with the potential waste disposal area shown in the 1970 high resolution aerial photograph, but
the 1970 aerial photograph indicates a larger disposal area which may be the case.
Geophysical results also identified a high-density anomaly consistent with a buried metal object
located within the waste disposal area to the north of the previously excavated area. Although it
could not be confirmed in the field, this anomaly may be indicative of a buried drum. No other
high-density anomalies consistent with buried metal were identified during GPR survey
activities. However, the known drum in the excavation sidewall was not identified by GPR;
Mr. Bill Schmithorst, PG
December 6, 2017
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therefore, additional buried drums may be present. The extent of disturbed soil based on H&H’s
interpretation of the GPR data and the location of the metallic anomaly are depicted on Figure 2.
Please note that the map in PUL’s report (Appendix B) is based strictly on GPR data, but H&H’s
Figure 2 considers the GPR data, H&H’s GPS data, H&H field observations, and other
information. Therefore, H&H’s mapped area of the GPR indicated disposal area differs slightly
from the map in PUL’s report.
3.0 Summary and Conclusions
In November 2017, H&H completed GPR survey activities in the southeastern portion of the Site
to approximate the extent of a waste disposal area and to evaluate subsurface conditions for the
presence of additional buried drums. GPR indicated disturbed soil consistent with reworking and
backfilling activities, which covered an approximate 1,400 sq ft area. This appears to be
generally consistent with the potential waste disposal area shown in the 1970 high resolution
aerial photograph, but the 1970 aerial photograph indicates a larger disposal area which may be
the case. Additional drums are likely present in the waste disposal area, but GPR did not indicate
the presence of numerous buried drums.
Please note that GPR is an imprecise tool and may not identify all subsurface anomalies.
Additionally, interpretation of the GPR results may have been complicated by dense vegetation
and decades of reworking soil in the areas of discarded wastes. As such, it is possible that
unidentified waste disposal areas and additional drums are present in the southeastern portion of
the Site.
Mr. Bill Schmithorst, PG
December 6, 2017
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It is good to work with you on this project. Should you have any questions or need additional
information, please do not hesitate to call us at (704) 586-0007.
Very truly yours, Hart & Hickman, PC
Ralph McGee, PG Matt Bramblett, PE
Senior Project Geologist Principal
Attachment
Cc: Ms. Lori Hinnant, K&L Gates (via email)
Mr. Michael Cain, Foundry Commercial (via email)
Mr. Jason Oriol, Foundry Commercial (via email)
SITE
0 2000 4000
APPROXIMATE
SCALE IN FEET
N
U.S.G.S. QUADRANGLE MAP
QUADRANGLE
7.5 MINUTE SERIES (TOPOGRAPHIC)
CHARLOTTE WEST, NORTH CAROLINA 1996
TITLE
PROJECT
SITE LOCATION MAP
UNDEVELOPED LAND
1900 CONTINENTAL BOULEVARD
CHARLOTTE, NORTH CAROLINA
DATE:
JOB NO:
REVISION NO:
FIGURE:
11-15-17 0
1LRC-005
JOB NO. LRC-005
REVISION NO. 0DATE: 12-6-17
FIGURE NO. 2
UNDEVELOPED PARCEL
1900 CONTINENTAL BOULEVARD
CHARLOTTE, NORTH CAROLINA
SITE MAP
2923 South Tryon Street-Suite 100Charlotte, North Carolina 28203704-586-0007(p) 704-586-0373(f)License # C-1269 / #C-245 Geology
LEGEND
SITE PROPERTY BOUNDARY
RAILROAD SPURS
PROPOSED BUILDING FOOTPRINT
APPROXIMATE EXTENT OF
POTENTIAL WASTE DISPOSAL BASED
ON HISTORICAL AERIAL REVIEW
PREVIOUS EXCAVATION AREA
HIGH DENSITY ANOMALY
(POSSIBLE DRUM)NOTES:
1.BASE MAP OBTAINED FROM MECKLENBURG CO. GIS
(2014).
2.H&H CONDUCTED ASSESSMENT ACTIVITIES ON OCTOBER 13, 14, 17, & 20 2016.
EXTENT OF SOIL DISTURBANCE
BASED ON GPR SURVEY
S:\AAA-Master Projects\LRC Patriot (LRC)\LRC-005 Brownfields New Building\Figures\Site Map.dwg, FIG 2, 11/30/2017 4:25:40 PM, zbarlow
Appendix A
1970 Aerial Photograph Map
REVISION NO. 0
JOB NO. LRC-005
DATE: 10-17-17
APPENDIX A
UNDEVELOPED PARCEL
1900CONTINENTAL BOULEVARD
CHARLOTTE, NORTH CAROLINA
1970 AERIAL PHOTOGRAPH MAP
LEGEND
SITE PROPERTY BOUNDARY
2923 South Tryon Street-Suite 100Charlotte, North Carolina 28203704-586-0007(p) 704-586-0373(f)License # C-1269 / #C-245 Geology
S:\AAA-Master Projects\LRC Patriot (LRC)\LRC-005 Brownfields New Building\Aerial Review\NCDOT Aerials - High Resolution\Aerial Review.dwgAREA OF WASTE DISPOSAL
Appendix B
GPR Investigation Summary Report; 1900 Continental Boulevard, Charlotte, North Carolina;
prepared by Probe Utility Locating, LLC on November 8, 2017
PO Box 135, Huntersville, NC 28070 - 704 594 1346 - info@probeutility.com - www.probeutility.com
November 8, 2017
Ralph McGee, PG
Hart & Hickman, PC
2923 South Tryon Street, Suite 100
Charlotte, NC 28203
RMcGee@harthickman.com
SUBJECT: GPR Investigation Summary Report
1900 Continental Boulevard
Charlotte, North Carolina
Dear Mr. McGee:
Probe Utility Locating, LLC (PUL) is pleased to submit this report of ground penetrating radar (GPR)
field investigation activities at the 1900 Continental Boulevard site in Charlotte, North Carolina. The
GPR investigation area measures approximately 100ft by 100ft and is located in a wooded portion of a
26-acre parcel owned by LRC-Patriot, LLC (Mecklenburg County parcel ID No. 20308305). Both the
site parcel and the GPR investigation area are shown on Figure 1. This field investigation was
conducted as part of an environmental assessment.
Based on information provided by Hart & Hickman, buried metal drums were discovered at the site
during past activities. An unknown number of drums were excavated and removed from the site at an
earlier date. Excavation and removal activities were stopped at some point and it was determined that
further assessment was necessary to determine the extent of any remaining buried drums. When PUL
was onsite, the former excavation appeared unaltered and was lined with plastic sheeting. It measured
approximately 30ft long by 20ft wide and between 0 and 6 feet deep. Water formed a pond in the center
of the excavation. Photos of the excavation area are included as Attachment C. According to Hart &
Hickman, at least one remaining metal drum was visible in one of the sidewalls of the excavation when
the excavation was fresh. PUL used a metal detector, shovels, and probing rods in an unsuccessful
attempt to locate the drum.
Ground cover in the vicinity of the excavation consists of weeds, moderate to dense woods and thick
brush. Portions of the site were cleared by PUL prior to this investigation to allow access for the GPR
field equipment. Several piles of concrete and debris were observed throughout the property, though
not in the immediate vicinity of the excavation.
GPR Investigation Report
1900 Continental Blvd Site
Page 2
PO Box 135, Huntersville, NC 28070 - 704 594 1346 - info@probeutility.com - www.probeutility.com
Scope or Work and Methods
PUL was requested by Hart & Hickman to perform a GPR investigation to assess the extent of metal
drums that potentially remain buried at the site. GPR methods can be used to visualize density
contrasts in the subsurface. For example, GPR can be used to identify an area that has been filled with
objects that have a different density than the surrounding soils. The GPR will not specifically identify
metal drums but since a buried drum typically has a higher density than the surrounding soil, the drum
can appear as a high-density anomaly. Additionally, the fill material that has been placed around the
drums may show as an anomaly if it differs in density from the surrounding soils.
Prior to conducting the field investigation, PUL performed a site reconnaissance visit with Hart &
Hickman on October 26th, 2017. During the site visit, it was determined that limited clearing of
underbrush and small trees would be necessary to allow access for the GPR equipment. PUL initially
planned to use a metal detector (in addition to the GPR) to help delineate the extent of potential buried
metal drums. During the site visit it turned out that the metal detector approach was not feasible due to
an abundance of metal objects (such as nails, pieces of wire, and fence posts) scattered in the vicinity
of the excavation.
On November 2nd, 2017, PUL mobilized a 2-person field crew to the site to perform brush clearing
activities and to conduct the GPR investigation. A Sensors & Software Noggin® GPR cart with a 250
MHz antenna was used for this investigation. Hart & Hickman field personnel recorded the GPR
transects and points of interest with a GPS unit. The GPS data was later provided to PUL for post-
processing. After initial test runs and a calibration period, PUL recorded nine GPR cross sections along
transects that were previously cleared of brush and vegetation. The location and extent of each GPR
transect is shown on Figure 2.
Results
Several GPR cross-sections included density anomalies that are indicative of ground disturbance or fill.
The density anomalies were distinct but generally not very pronounced. This may partially be because
the subsurface at the site has not been disturbed in several decades and the fill material has similar
compaction and composition as the surrounding soil. The effective GPR signal penetration depth was
approximately 5-6ft.
The locations, approximate lengths and directions of the nine recorded GPR cross-sections (A-A’
through I-I’) are shown on Figure 2 and the cross-sectional profiles are included as Attachment B of
this report. Cross-sections B-B’, C-C’, D-D’, E-E’, F-F’ and I-I’ show the transition from undisturbed soil
to what appears to be fill material. Cross-sections A-A’, G-G’, and H-H’ did not show significant density
anomalies and are considered outside the fill area. Please refer to Attachment B for a more detailed
discussion of each cross-sectional profile.
The estimated extent of the density anomaly is generally 20ft or less from the edge of the current
excavation. The approximate lateral extent of the density anomaly is shown on Figure 2. As discussed
previously, no visual evidence of drums was observed during the field investigation and the metal
detector was not useful in delineating the extent of potential drums. It should be noted that cross-
GPR Investigation Report
1900 Continental Blvd Site
Page 3
PO Box 135, Huntersville, NC 28070 - 704 594 1346 - info@probeutility.com - www.probeutility.com
section F-F’ includes an object of very high density a depth of approximately 5ft. This anomaly could
potentially be a buried metal drum.
Limitations
Due to access and equipment limitations, and the limited scope of this investigation, PUL may not have
identified every underground structure or anomaly present at the site. Additionally, the performance of
the GPR equipment depends heavily on soil type and properties. Features that are similar in density to
the surrounding soils may be difficult or impossible to see via GPR methods.
Closing
We appreciate the opportunity to prepare this report and it was a pleasure to work with you on this
project. Please do not hesitate to contact me via phone at (704) 594-1346 or via email at
Carlo.Zanon@probeutility.com should you have any questions regarding this report.
Sincerely,
Carlo Zanon
Probe Utility Locating, LLC
Attachments: Attachment A – Figures
Figure 1: Site Location and Layout
Figure 2: GPR Investigation Results
Attachment B – GPR Cross-Sections
Attachment C – Site Photographs
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Attachment A
Figures
1900 Continental Boulevard
Charlotte, NC
Site Parcel
Parcel Boundaries
Cross-Section Transects
Edge of GPR Anomaly along Transect
Extent of Excavation (Approximate)
Extent of GPR Anomaly (Approximate)
Legend
1900 CONTINENTAL BOULEVARD
CHARLOTTE, NORTH CAROLINA
CLIENT: HART & HICKMAN DATE: 11-8-2017
GPR INVESTIGATION RESULTS FIGURE 2
0 20 40 60 80 ft PROBE UTILITY LOCATING, LLC
PO BOX 135, HUNTERSVILLE, NC
WWW.PROBEUTILITY.COM
SITE PARCEL
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Notes:
- The locations of the GPR cross-section transects are based on GPS measurements taken by Hart & Hickman on November 2nd, 2017.
- Areas and extents of the excavation and GPR anomaly are approximate and based on field measurements and interpretation of the GPR data.
- Parcel boundaries obtained from Mecklenburg County OpenMapping GIS Portal.
- 2015 Aerial imagery and elevation contours obtained from NC OneMap.
- ft msl = feet above mean sea level; GPR = Ground Penetrating Radar; GPS = Global Positioning System
- The GPR cross-sections are labeled A-A' through I-I'. The cross-sectional profile for each transect is included as an appendix.RAILROAD
TRACKS
A
A'UNNAMED TR
IBUTARY
B'
B
C'
C
D
D'
E'
E
F
F'
G
G'
H
H'
I
I'
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Attachment B
GPR Cross-Sections
1900 Continental Boulevard
Charlotte, NC
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 1
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
The following pages contain a total of nine GPR cross-sectional profiles that were recorded in an effort to delineate the area of ground disturbance.
Location and extent of the cross-section transects are shown on Figure 2 in Attachment A. The x-axis of each profile represents distance in feet and
the y-axis is depth below ground surface in feet. The colors represent relative differences in density. Blue equals low relative density, green is
intermediate and yellow/red indicate higher densities. The interpreted boundaries of density anomalies (if observed) are shown by red vertical line(s)
on each cross-sectional profile.
Cross-Section A-A’: The transect starts at a point north of the excavation and ends at the edge of the excavation. The total length is approximately
100ft. Visible evidence of plastic and black soil was observed at approximately 70 ft. The GPR profile does not indicate significant fill or density
anomalies and the soil appears to be relatively undisturbed. Small anomalies represent tree roots and/or rocks.
A’
South
A
North
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 2
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section B-B’: The transect runs along the southern edge of the excavation and has a total length of approximately 95ft. A density anomaly
indicative of fill was observed from approximately 45ft to 73ft.
B’
Southwest
B
Northeast
Fill / Anomaly
Undisturbed Soil
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 3
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section C-C’: The transect starts at a point southeast of the excavation and ends at the edge of the excavation. The total length is
approximately 35ft. A minor density anomaly that could be indicative of fill was observed from approximately 25ft to the end of the transect.
C’
Northwest
C
Southeast
Fill / Anomaly
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 4
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section D-D’: The transect starts at a point south of the excavation and ends at the edge of the excavation. The total length is approximately
30ft. The first 25ft of the profile is not indicative of fill. A natural drainage ditch at 12ft results in a density anomaly but it is not indicative of fill.
Increased density was also observed past 25 ft, partly due to a large boulder (field verified via digging) at 27ft. The last 5 feet of the profile (including
the boulder) are interpreted as fill.
D’
North
D
South
Drainage
Ditch/Depression
Boulder
Fill / Anomaly
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 5
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Cross-Section E-E’: The transect starts at a point east of the excavation and ends at the edge of the excavation. The total length is approximately
30ft. A minor density anomaly that is interpreted as fill was observed from approximately 19ft to the end of the transect.
E’
East
E
West
Fill / Anomaly
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 6
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section F-F’: The 70ft long transect runs parallel to the northeastern edge of the excavation (10ft away). Two minor density anomalies that
could be indicative of fill were observed from approximately 7ft to 30ft and 45ft to 52ft, respectively. Additionally, a distinct very high density anomaly
was present at approximately 17ft at a depth of 5 ft. It is possible that this could represent a metal drum or similar object.
F’
Northeast
F
Southwest
Fill / Anomaly
Undisturbed Soil
Undisturbed Soil
Potential Drum
(Very High
Density Anomaly)
Fill / Anomaly
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 7
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section G-G’: The transect is parallel to both the northeastern edge of the excavation and cross-section F-F’. At its nearest point, cross-
section G-G’ is approximately 30ft away from the excavation. The GPR profile does not suggest fill / soil disturbance.
G’
Southwest
G
Northeast
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 8
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section H-H’: The transect starts at a point north of the excavation and ends at the edge of the excavation. The total length is approximately
32ft. The GPR profile is not indicative of fill / soil disturbance.
H’
South/Southeast
H
North/Northwest
Undisturbed Soil
Attachment B – GPR Cross-Sections
1900 Continental Blvd Site
Page 9
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Cross-Section I-I’: The transect starts at a point northeast of the excavation and ends at the eastern edge of the excavation. The total length is
approximately 65ft. A density anomaly that could be indicative of fill was observed from approximately 58ft to the end of the transect.
I’
South/Southwest
I
North/Northeast
Fill / Anomaly
Undisturbed Soil
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Attachment C
Site Photographs
1900 Continental Boulevard
Charlotte, NC
Attachment C: Site Photographs
1900 Continental Blvd Site
Page 1
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Photo 1: View of the excavation area looking towards the southwest. Photo was taken prior to site clearing
activities.
Photo 2: Same view as Photo 1 but after limited site clearing was conducted. The plastic sheeting was pulled
back to look for drums in the excavation sidewall.
Attachment C: Site Photographs
1900 Continental Blvd Site
Page 2
Probe Utility Locating, LLC - info@probeutility.com - www.probeutility.com
Photo 3: View of the northern and western sidewall of the excavation. The pond is in the center of the excavation.
White pin flags represent beginning or end points of GPR cross-section transects. View is towards the
west/northwest.
Photo 4: Photograph taken at the eastern corner of the excavation looking towards the northwest.