09044_Willard Lead Modeling & Approval 20120626

1601 Mail Service Center, Raleigh, North Carolina 27699-1601
Phone: [phone] \ Internet: www.ncdenr.gov
An Equal Opportunity \ Affirmative Action Employer – 50% Recycled \ 10% Post Consumer Paper

North Carolina Department of Environment and Natural Resources

Beverly Eaves Perdue
Governor
Dee Freeman
Secretary

June 26, 2012

Sent Via E-mail ([e-mail])

Stuart Proffitt
The Fountains at New Bern Station
1355 Greenwood Cliff, Suite 150
Charlotte, NC 28204

Subject: Approval for Soil Stabilization
Willard Lead , Fountains at New Bern
Charlotte, Mecklenburg County
Brownfields Project Numbers 09044-05-60 and 15014-11-60

Dear Mr. Proffitt:
On May 16, 2012, the North Carolina Brownfields Program (NCBP) received a Proposal
for Soil Stabilization Modeling prepared by Terracon for the above referenced site. At the
request of NCBF, a supporting document was submitted on June 16, 2012 by Terracan a Report
of Soil Leachability Modeling. After reviewing both documents, the NCBP approves the scope
of services outlined in the Proposal for Soil Stabilization.

Be advised that this approval from the Brownfields Program does not waive any
applicable requirement to obtain any necessary permits, licenses or certifications for the above
listed activities nor does it waive any requirement to comply with applicable law for such
activities. If you have questions about this correspondence or require additional information,
please contact me by phone at 704/661-0330, or by e-mail at [e-mail].

Sincerely,

Carolyn Minnich
Carolyn Minnich
Brownfields Project Manager
Division of Waste Management

cc: Project File
ec: Bruce Nicholson, NCDENR
Stephen Brown, [e-mail]
Franchina, Dave, [e-mail]

Terracon Consultants, Inc. 2020-E Starita Road Charlotte, North Carolina 28206
P [704] 509 1777 F [704] 509 1888 terracon.com

May 16, 2012

Ms. Carolyn Minnich, Project Manager
North Carolina Department of Environment and Natural Resources
Division of Waste Management - Brownfields Program
Mail Service Center 1646
Raleigh, North Carolina 27699-1646

RE: Proposal for Soil Stabilization Modeling
The Fountains at New Bern Station
New Bern Street at Foster Avenue
Charlotte, North Carolina
North Carolina Brownfields Project Nos. 09044-05-60 and 15014-11-60

Dear Ms. Minnich:

Terracon Consultants, Inc. (Terracon), on behalf of Fountains at NewBern Station, LLC and
NewBern Station Holdings, LLC, is pleased to submit this proposal to the North Carolina
Brownfields Program (NCBP) to conduct an evaluation of the long term leachability of soils after
the soils have been stabilized by cementation at the above-referenced site.

Our goal is to demonstrate cementation stabilization is an effective method of controlling the
leachability of lead from impacted soils at the site; and thus, is an appropriate method to ensure
that soil management at the site is protective of groundwater. This proposal is being provided in
response to a request from the NCBP. Project information, scope of services and a project
schedule are provided in the following sections.

A. BACKGROUND INFORMATION

After many months of discussion and analysis, on December 2, 2011, the NCDENR Brownfields
Program received a draft Risk Management Plan (RMP) prepared by Terracon for the above
referenced Brownfields property. This document was submitted in accordance with the Notice of
Brownfields Property recorded in August 2007. After several discussions and comments on the
draft document, Terracon submitted RMP Revision 2 on December 13, 2011. Further revisions
were required by NCDENR Brownfields Program in late December 2011 and incorporated into
the RMP prior to final acceptance of the RMP Version 4 on January 18, 2012.
Proposal for Soil Stabilization Modeling
The Fountains at New Bern Station ■ Charlotte, North Carolina
May 16, 2012 ■ Terracon Project No. 71117723

Reliable ■ Responsive ■ Resourceful 2

This proposal is a supplement to the RMP approved by the North Carolina Brownfields Program
(NCBP). The following items were included in the RMP that was approved by the NCBP:
■ Lead impacted soils that are moved during construction activities will be stabilized on
site and placed in the designated Soil Cap Area.
■ Soils planned for placement in the designated Soil Cap Area may be stabilized by
solidification/cementation.
■ Solidification/cementation reduces the hazard potential by converting the contaminants
into their least soluble, mobile or toxic form, thus minimizing their potential to migrate.
■ Binding and hardening material ties up the free water in the matrix with the cement
chemically bonding to the lead contaminants.
■ Samples of the stabilized material will be submitted for laboratory analysis of lead by
SPLP.
■ Analytical results will be compared to NCDENR regulatory action levels.

B. SITE PRE-CONSTRUCTION CONDITIONS

Previous assessments have detected lead concentrations in soils above regulatory levels on the
site ranging from 530 milligrams per kilograms (mg/kg) to 160,000 mg/kg. Uncapped soils
containing lead concentrations of approximately 61,000 mg/kg were identified in the
southwestern portion of the site. At the time the site was acquired by the prospective developer
(PD), most of the pavement cover was cracked and broken allowing precipitation to percolate
through the subsurface soils and ultimately impact the groundwater. Groundwater below the
proposed Soil Cap Area of the site contained lead concentrations as high as 1,560 micrograms
per liter (µg/L).

C. CURRENT PROJECT INFORMATION

Soils containing lead as a contaminant of concern (COC) currently located in a staging area in
the southeastern portion of the site are planned for solidification stabilization. Solidification
stabilization reduces the hazard potential of the COC by converting the lead into its least
soluble, mobile or toxic form; thus, minimizing its potential to migrate or leach.

The PD plans to use cement to solidify soils containing lead, after which the soils will be placed
in a Soil Cap Area. The Soil Cap Area will be noted on the Brownfields Plat which, after
approval by the NCBP, will be recorded with the Mecklenburg County Register of Deeds The
Soil Cap Area will be capped with an asphalt cover described in greater detail below.

The Environmental Protection Agency (EPA) and other State regulatory agencies utilize several
analytical leaching procedures in order to simulate waste disposal environments and to
Proposal for Soil Stabilization Modeling
The Fountains at New Bern Station ■ Charlotte, North Carolina
May 16, 2012 ■ Terracon Project No. 71117723

Reliable ■ Responsive ■ Resourceful 3

characterize a waste's toxicity to its surroundings. The Toxicity Characteristic Leaching
Procedure (TCLP) is perhaps the most commonly used leaching procedure which uses a
leaching solution of acetic acid to simulate the long term effects of disposal of industrial and
non-industrial wastes within a municipal solid waste landfill.

The Synthetic Precipitation Leaching Procedure (SPLP) is an alternate method developed to
simulate leaching under acid rain conditions. The procedure is similar to the TCLP; however, the
pH is less acidic than the TCLP test, using a dilute nitric/sulfuric acid mixture.

Another more stringent leaching method is the Multiple Extraction Procedure (MEP) which is
designed to model 1000 years of freeze and thaw cycles and a prolonged exposure to a
leaching medium. This procedure involves an initial extraction with acetic acid (much like the
TCLP method) followed by many subsequent tumbling/extractions with a synthetic acid rain
solution (sulfuric/nitric acid). We propose use the MEP as a model for evaluating the long term
leachability of stabilized soils at the site.

D. EXPECTATIONS

There are physical and chemical conditions that would be expected to impact the solidified
material and have a potential to compromise the stability of the materials. These conditions
include chemical and physical weathering, loading stress and movement.

The solidified material will be placed well above the seasonal fluctuations of groundwater;
therefore, we do not expect permanent or periodic saturation events to occur within the
stabilized materials. Runoff from precipitation will be captured by pavements, curbs and gutters
and directed to an underground stormwater sewer system, reducing the impact potential of
infiltration. The grade is designed so that there will be no ponding of water on the asphalt.
Furthermore, the Brownfields Agreement requires the pavement (cap/cover) to be maintained in
perpetuity; therefore, we would not expect surface water to percolate through the solidified
material.

Once the contaminated soils are stabilized by cementation, we anticipate the permeability of the
solidified material to be in the range of 1x10-9 centimeters per second (cm/sec). A typical clay-
lined municipal landfill has a permeability of approximately 1x10-7 cm/sec. Hence, the stabilized
soils will have a permeability that is two orders of magnitude LESS permeable than a clay-lined
municipal landfill. In our opinion, the potential effect of chemical and physical weathering on the
solidified material is minimal, and the risk of a material volume of groundwater permeating the
solidified material and reaching site groundwater is low.

The pavement above the solidified material will be designed to distribute the load of parked cars
across the entire parking lot area; therefore, we would not expect loading stresses to be a
significant force to impact the underlying materials.

Proposal for Soil Stabilization Modeling
The Fountains at New Bern Station ■ Charlotte, North Carolina
May 16, 2012 ■ Terracon Project No. 71117723

Reliable ■ Responsive ■ Resourceful 4

The force of gravity and the potential for movement by settlement is not considered significant
enough to compromise the stability of the solidified materials. In the area of the site, the
estimated potential for movement (shear force) attributable to seismic activity is 1.2 times the
force of gravity. This amount of movement is not enough to crack or damage the solidified
materials.

We anticipate the MEP testing will simulate conditions that are more stringent than the
conditions expected to occur at the site – and hence protective of groundwater -- for the
following reasons: (1) none of the conditions identified above are expected to significantly
impact the stabilized material, (2) the volume of any liquid that leaches through the solidified
material is expected to be minimal; (3) groundwater beneath the Soil Cap Area is already
significantly impacted (1,560 µg/L); and (4) the consolidation and stabilization of soils on the site
will place such soils into a far more controlled environment than prior to construction.

E. SCOPE OF SERVICES

The scope of services will include (but is not limited to) the following elements:

■ A pilot study is currently in progress to identify an appropriate mix design that will
stabilize lead within a cement matrix.
■ The pilot study samples will be submitted for analysis of total lead by EPA Method 6010
and lead by the Synthetic Precipitation Leaching Procedure (SPLP) by EPA Method
1312/6010.
■ Once a desired mix design is identified, the sample will be further analyzed for lead by
the Multiple Extraction Procedure (EPA Method 1320). This sample will be exposed to
as many as 5 tumbling/extraction events.
■ The US Environmental Protection Agency (EPA) evaluates whether materials may be
disposed of safely outside its hazardous waste regulatory regime, in part, based on
leachate concentrations. The EPA has defined lead leachate concentrations below 5.0
mg/L as not being reflective of a hazardous waste, and hence suitable for management
in a non-hazardous waste landfill. This, in turn, presumes that the disposal is protective
of groundwater if placed in a non-permeable environment, like an adequately designed
municipal landfill or the cement stabilization being proposed by the PD. Therefore, we
would expect an acceptable result to not exceed 5.0 mg/L.
■ The analytical results will be discussed in our report.

Preparation of the Report

Upon completion of field and laboratory activities and receipt of the analytical results, a written
report will be prepared that will include the following items:
Proposal for Soil Stabilization Modeling
The Fountains at New Bern Station ■ Charlotte, North Carolina
May 16, 2012 ■ Terracon Project No. 71117723

Reliable ■ Responsive ■ Resourceful 5

 Documentation of activities;
 Analytical laboratory results;
 Data evaluation and presentation of findings; and,
 Recommendations concerning further action, if necessary.

Schedule

Work can begin within 24 hours of your notification to proceed. Reporting is estimated at
approximately 1 to 2 days. Total estimated time for mix design and laboratory analysis will be
approximately 3 to 4 weeks.
F. SUMMARY

Previous assessments have detected lead concentrations in soils above regulatory levels on the
site ranging from 530 mg/kg to 160,000 mg/kg. In addition, groundwater below the proposed
Soil Cap Area of the site contains lead concentrations as high as 1,560 µg/L.

Once the contaminated soils are stabilized, the lead contaminants will be chemically bonded to
the cement matrix and as a result, would not be leachable at the levels attained by pre-existing
conditions. Use of SPLP and MEP, described above, as the model for evaluating the long term
leachability of stabilized soils at the site will ensure protection of the site’s currently impacted
groundwater.

We appreciate the opportunity to provide this proposal and look forward to our continued work
with you on this project. If you have any questions or comments regarding this proposal, please
contact us at [phone].

Sincerely,
Terracon Consultants, Inc.

Stephen C. Brown Christopher L. Corbitt, PG
Project Geologist Environmental Services Manager