10036_South End Transit_Vapor_Barrier_Verification_Letter_12-12-2012-OCR

December 12, 2012

Mr. Tony Duque
NC Brownfields Program
1646 Mail Service Center, Room 3409-K
Raleigh NC 27699-1646

Re: Verification Letter - Subsurface Vapor Mitigation System Installation
Transit-Oriented, Multi-Family Residential Project, Southline Apartments
140 Remount Road, Charlotte, North Carolina (the “Property”)
PSI Project Number: 0457116
Brownfields Project Number # 10036-06-60

Dear Mr. Duque:

From the period of April 2012 through August 2012, representatives of PSI conducted
part-time, periodic field observations of the subsurface portion of the vapor mitigation
system for the above referenced project. These observations were conducted to
document that the vapor mitigation system piping and vapor barrier were installed in
accordance with the project’s plans (Vapor Mitigation System, dated December 2012),
PSI’s recommendations and the manufacturer’s specifications. The specifications were
submitted to NCDENR in advanced and approved by Mr. Will Service of the NCDENR
Brownfields Program on November 10, 2012. A total of eight-teen (18) residential
buildings and the club house were inspected in respect to the vapor mitigation
systems.

The structures at the subject property were designed to accommodate a passive vapor
mitigation system and vapor barrier system. The passive vapor mitigation system
consists of a horizontal gravel trench, with a 4-inch diameter polyvinyl chloride (PVC)
well screen (Schedule 40, 0.040 inch slot size). The horizontal well screen is covered
with a geotextile sock, and is connected to a vertical riser which extends to the roof. A
3/8-inch Teflon sampling tube was attached to the outside of the horizontal well
screen, terminating in the center of the structure, and accessible from the outside of
the building foundation. Each building has a minimum of one horizontal well screen,
running axially along the slab centerline. Buildings constructed on a split, multi-level
slab are constructed with one horizontal well screen and one vertical riser casing for
each multi-level slab section.

The vapor barrier system consists of 10 mil, reinforced high density polyethylene
(HDPE), chemical resistant sheeting (STAGO® Wrap Vapor Barrier). The vapor barrier
Subsurface Mitigation System Verification Letter December 12, 2012
Southline Apartments, Charlotte, North Carolina Page 2 of 2
PSI Project No. 0457116

is sealed at the overlap joints and at all penetrations with compatible sealants and/or
tape.

Based on our observations, to the best of our knowledge and belief, the subsurface
portion of the vapor mitigation system has been installed in general accordance with
the project specifications.

Please note that PSI has completed the required Sub-Slab Vapor Sampling as
outlined in the Post Construction Sub-slab Vapor Sampling Work Plan (April 2012).
The results are presented in a report issued under a separate cover.

We trust this letter is responsive to your needs. If you have any questions regarding
this letter, please do not hesitate to contact our office at 704-598-2234.

Sincerely,
PROFESSIONAL SERVICE INDUSTRIES, INC.

Mark R. McCagg Bryan M. Lucas
Project Scientist Senior Project Manager
Environmental Services