19040_Atando Ave_RAA IHSB Ltr Resp 20150709

610 East Center Avenue, Suite 301, Mooresville, North Carolina 28115
Phone: [phone] \ Internet: http://portal.ncdenr.org/web/wm
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North Carolina Department of Environment and Natural Resources

Pat McCrory Donald R. van der Vaart
Governor Secretary

July 9, 2015

Mr. William Stokesbury, Esq Via Electronic Mail - [e-mail]
Stokesbury, Shipman & Fingold, LLC
10 Waterside Drive, Suite 204
Farmington, CT 06032

Re: IHSB COMMENTS OF TERRACON PROPOSAL FOR BROWNFIELDS SERVICES
Property Address: 527 Atando Ave, Charlotte, Mecklenburg Co., NC 28206
Site: Atando Ave Solvent Contamination
IHSB Incident: NONCD0001992

Dear Mr. Stokesbury:
The Inactive Hazardous Sites Branch (IHSB) of the Division of Waste Management (Division) conducted a
conference call with you, your client, their consultant, the North Carolina (NC) Brownfields Program, and the
prospective buyer to discuss the current and historically known groundwater solvent contamination of
tetrachloroethene (PCE) and trichloroethene (TCE) at the Site. Additional assessment and delineation of the soil and
groundwater contamination as well as vapor intrusion (VI) evaluation is needed at this property. Under the Inactive
Hazardous Sites Act, a Site is the area on which contamination has not only been released (if known) but also the
area onto which the contamination has come to be located. A Site in the IHSB can encompass multiple properties.

Based on review of the Proposal for Brownfields Services provided by your client’s consultant, Terracon
Consultants, Inc. (Terracon), outlining additional assessment, the Division, IHSB and the NC Brownfields Program
offers the following general comments:

1. A thorough review of historical files for site uses and chemical inventory used at the site should be conducted.
Care should be taken to review and account for any storage tanks installed, used, abandoned, or removed at the
property and their historical and current uses. The Division suggest further investigation on the past location and
use of tank 3 (one of three 6000-gallon tanks installed in 1966 and reportedly removed in 1985). Please see
“Note” below in reference to investigation related to petroleum substances.
2. Please ensure laboratory analyses and data used to evaluate site contaminants conform to the IHSB’s Guidelines
and use the appropriate US EPA Method or method published in the Standard Methods for the Examination of
Water and Wastewater (latest edition) having the lowest method detection limit or one that achieves the 15A
NCAC 2L standards for water samples and Branch unrestricted use remediation goals for soil. Essentially,
analytical data reporting limits should achieve sample quantitation limits less than or equal to the 15A NCAC 2L
groundwater standards or alternatively, they must state in the case narrative that the sample quantitation limits
are the lowest that can be achieved using U.S. EPA-approved methods. The laboratory must provide a written
explanation for any sample having sample quantitation limits that exceed 10 times the US EPA method detection
limits. Please refer to Appendix A: Sampling and Analytical Procedures for the Remedial Investigation of the
Guidelines for more details on sampling, analytical methods, and reporting requirements.
3. Groundwater concentrations of PCE and TCE exceeded Division’s potential vapor intrusion screening levels.
An evaluation for vapor intrusion potential at this Site and/or adjacent properties is needed. Division’s
“Supplemental Guidelines for the Evaluation of Structural Vapor Intrusion Potential” (Vapor Guidelines) should
be used in conducting an evaluation of structural vapor intrusion potential. The Vapor Guidelines and updated
Mr. William Stokesbury, Atando Ave Solvent Contamination Page 2 of 2
July 9, 2015
Screening Levels can be accessed on the Branch’s website at: http://portal.ncdenr.org/web/wm/dwm-new-vapor-
guidance. To evaluate and further delineate the vapor intrusion at the Site is recommended that you install vapor
sample points inside and outside the facility. We also strongly suggest you evaluate the residential properties
southwest of MW-8 during your preliminary vapor intrusion screening.
4. The Division suggests that you perform additional groundwater delineation not only in the area of MW-5 and
towards the suspected source area, but also in the area of MW-8.
5. The previously provided onsite soil data does not fully meet IHSB’s Guidelines for Assessment and Cleanup
which states, “If actual contaminants released are unknown, mobile contaminants or contaminants that have been
detected in groundwater at the site, a soil boring should be advanced to the water table. The boring should be
centrally located in the area of concern and adequately sampled at intervals from ground surface to the water
table. Examples of sampling intervals include 0 to 6 inches below ground surface, every five feet from 6 inches
to the water table, and at the water table. Additional sampling depths should also be chosen based on visual and
field-screening evidence.” (Appendix A, A.2.1.2.1.b.). The collected samples were taken from the water table
only and are insufficient to allow for any conclusions determining whether Volatile Organic Compounds (VOCs)
detected in groundwater at the Site are related to on-property or off-property sources. The Branch suggests
additional soil sampling data be collected from the Site in suspected source areas, especially in the vicinity of
MW-5 and MW-8, and, if possible, at off-property suspected source areas. Any additional confirmatory soil
sampling should follow the procedures in Appendix A of the IHSB’s Guidelines for Assessment and Cleanup.
The most current version of the Guidelines and other guidance materials can be accessed by visiting the IHSB’s
website at: http://portal.ncdenr.org/web/wm/sf/ihshome.
6. Soil samples should be laboratory analyzed for VOCs by EPA Method 8260 and for metals by the USEPA
method or methods published in Standard Methods for the Examination of Water and Wastewater having the
lowest detection limits or having detection limits below the 15A NCAC 2L standards (please refer to IHSB
Guidelines for further information).
7. Please conduct a comprehensive 1500-foot-radius receptor survey to include water supply usage, and confirm the
current usage status of any identified supply wells. Samples should be collected from residential supply wells
identified in the survey area and laboratory analyzed for VOCs by EPA Method 8260.
8. Prepare groundwater and soil analytical results summary tables with historical and current sampling data.
Collect and submit a full round of sampling data from the entire onsite and/or offsite groundwater monitoring
well network.

Note: Any investigation or remediation related to petroleum compounds should be conducted in accordance with the
Division of Waste Management UST Section’s regulations and guidance documents. Future investigation or remediation
reports related to petroleum substances will be the responsibility of the Division of Waste Management’s UST Section and
should be forwarded to the attention of Ron Taraban of the UST Section in the Mooresville Regional Office.

For additional information regarding the Brownfields Program, please contact Ms. Carolyn Minnich at
[e-mail] or 704-661-0330. Additional details about the Brownfields Program can be found on their
website at http://portal.ncdenr.org/web/wm/bf. Additional information regarding the Inactive Hazardous Sites
Program can be found at http://portal.ncdenr.org/web/wm/sf/ihshome. If you have any questions, please call me at
[phone], ext. 2191. Thank you in advance for your cooperation.

Sincerely,

Miguel A. Alvalle, Hydrogeologist
Division of Waste Management – NCDENR

Ec: Carolyn Minnich, Brownfields Program – NCDENR, [e-mail]
Chris Corbitt, Terracon Consultants Inc., [e-mail]