20089_Hendrick_Auto_FINAL_Soil-Gas_Assmt_20150925

September 25, 2015

Mr. Eric Applefield
Southern Apartment Group, LLC
1435 West Morehead Street, Suite 130
Charlotte, North Carolina 28208

Subject: SOIL GAS SAMPLING LETTER REPORT
FORMER HENDRICK DURHAM AUTO MALL
PARCEL A
409 SOUTH ROXBORO STREET
DURHAM, DURHAM COUNTY, NORTH CAROLINA
MID-ATLANTIC JOB NUMBER: R2698.00 TASK 01000

Dear Mr. Applefield:

Mid-Atlantic Associates, Inc. is pleased to present this Soil Gas Sampling Letter Report for the
above-referenced site. The sampling was conducted in general accordance with Mid-Atlantic
Proposal P15R-7203 dated June 23, 2015.

The subject property is located at 409 South Roxboro Street in Durham, Durham County, North
Carolina. The site is currently vacant and most of the buildings once associated with the
Hendrick Durham Auto Mall have been razed. Based on a draft Report of Soil-Gas Assessment
dated June 16, 2015 and prepared by ECS Carolinas, LLP, 1,4-dichlorobenzene was detected
in three shallow soil-gas samples collected at the site at concentrations exceeding its residential
vapor intrusion screening level. At your request, Mid-Atlantic collected three deeper soil-gas
samples at the subject site in general accordance with the North Carolina Department of
Environment and Natural Resources, Division of Waste Management, Vapor Intrusion Guidance
(April 2014). This report documents the results of these activities.

Initially the sampling plan was to collect the deep soil gas samples in the immediate proximity of
the three sub-slab soil gas sample locations sampled by ECS. However two items have
changed since the sampling plan was first developed. First, the redevelopment plan changed so
that the proposed building locations are different now compared to how they were originally
planned. The second change is that the redevelopment of eastern portion of the site is going to
take place much later than the development of the western portion of the site (aka Parcel A).
One of the ECS sample locations is on the eastern portion of the site. No soil gas sample was
collected in the vicinity of this sub-slap soil gas sample.

The attached drawing shows the location of the original three ECS sub-slab soil gas sample
locations and the three deeper soil gas sample locations used for this assessment. All three of
the soil gas sample locations (101 thru 103) are located where current development plans
indicate that occupied building space will be constructed, (e.g. not parking areas). Two of the
Letter Report of Soil Gas Sampling September 25, 2015
Former Hendrick Durham Auto Mall Page 2
Durham, North Carolina

three soil gas sample locations are in close proximity to the two ECS sub-slab soil gas samples
located on Parcel A.

At each soil-gas location, the pavement was removed and cleared from the boring location and
a boring was advanced to a depth of six to seven feet below land surface using a direct push
drill rig. One-quarter inch outer diameter Nylon tubing was inserted into each boring to within
four inches of the bottom of the boring. A filter tip was placed on the tip of the tubing and a sand
pack was installed around the filter tip and tubing approximately one foot from the bottom of the
boring. A six-inch thick hydrated bentonite seal was installed above the sand pack. The
assembly was leak tested prior to sampling. A laboratory supplied summa canister was attached
to the tubing to collect a soil gas sample. Air within the nylon tubing and sand pack was purged
prior to sample collection. Each sample was submitted to the laboratory for analysis using EPA
Method TO-15 for 1,4-dichlorobenzene.

The laboratory analytical report is attached to this letter report. The compound 1,4-dichlorobenzene
was not detected in any of the three soil gas samples collected. The method detection limits for
each tested sample were below the Residential Vapor Intrusion Screening Level for Exterior Soil
Gas.

When the I,4-dichlorobenzene was detected in the sub-slab soil gas samples collected by ECS, it
was theorized that the source may have been the asphalt pavement present at the sampling
locations. The absence of this compound at the greater sampling depth used in this assessment
tends to support that theory. As such, the data collected during this assessment suggests that 1,4-
dichlorbenzene does not present a vapor intrusion concern.

We appreciate the opportunity to present this report to Southern Apartment Group, LLC. If you
have any questions or need additional information, please feel free to contact us at 919-250-9918.

Sincerely,

MID-ATLANTIC ASSOCIATES, INC.

Daniel H. Nielsen, PE
Principal Engineer

Darin M. McClure, PE
Principal Engineer

Attachment: Drawing
Laboratory Report

DRAWING
!A
!A
!A
!A
!A
!A
HOTEL
MIXED USE
COMMERCIAL
OFFICE
M U L T I -F A M I L Y
´
SOIL GAS SAMPLE LOCATION MAP FORMER HENDRICKS DURHAM AUTO MALL409 SOUTH ROXBORO STREET AND 464 EAST PETTIGREW STREETDURHAM, NORTH CAROLINA
DRAWN BY:
DRAFT CHECK BY:
ENGINEER CHECK BY:
APPROVED BY:
DATE: SEPTEMBER 2015
JOB NO.: 000R2698.00
GIS NO.: 04G-R2698.00-03
DRAWING NO.: 1
REFERENCE: 2013 AERIAL IMAGERY FROM NC ONE MAPS. PROPERTY BOUNDARY AND ROAD GIS FROM DURHAM COUNTY GIS. ECS SUB-SLAB SAMPLE LOCATION DATA FROM ECS CAROLINAS SOIL-GAS SAMPLE LOCATION MAP. MID-ATLANTIC FIELD NOTES.
LEGEND
SUBJECT SITE
!A MID-ATLANTIC SOIL GAS SAMPLE LOCATION
!A ECS SUB-SLAB SAMPLE LOCATION
PLANNED PARKING GARAGE
PLANNED RESIDENTIAL/COMMERCIAL BUILDING
0 100 200 300 400Feet
1:1,200
JACKIE ROBINSON
SOUTH DILLARD
SG-101
SG-3
SG-2
SG-1
SG-102
SG-103

LABORATORY REPORT