1812_Duke_Marshall_ RequestCQARevise_DIN27618_20170410

526 South Church Street:
Mail Code EC13K
Charlotte, North Carolina 28202
980-373-5697

April 7, 2017 North Carolina Department of Environmental Quality
Division of Waste Management Solid Waste Section
2090 U.S. Highway 70
Swannanoa, North Carolina 28778
Attn: Mr. Larry Frost
Re: Industrial Landfill No.1 Cells 3 and 4 Specification & CQA Plan Revision Request Permit No.: 1812-INDUS
Marshall Steam Station Catawba County
Terrell, North Carolina 28682
Dear Mr. Frost,

As discussed via phone conversation on April 5, 2017, Duke Energy requests approval for the proposed Specification and Construction Quality Assurance (CQA) Plan changes found in the attached letter titled
Specification & CQA Plan Revision Recommendations for Marshall Steam Station’s Industrial Landfill
No. 1 (Permit No. 1812-INDUS).
If there are any questions regarding this request, please contact me at [phone].
Respectfully Submitted,
Tyler Hardin Environmental Services Cc (via e-mail): Ed Mussler, NCDEQ
Leo Furlong, Duke Energy
Kyle Baucom, Duke Energy
Dan Zakary, Duke Energy
Jeff Jones, Duke Energy

S&ME, Inc. | 9751 Southern Pine Boulevard | Charlotte, NC 28273 | p 704.523.4726 | f 704.525.3953 | www.smeinc.com

April 7, 2017
Duke Energy
Marshall Steam Station, Issue No. MAR-131
8320 East NC Highway 150
Terrell, North Carolina 28682

Attention: Mr. Kyle Baucom, P.E.
Tyler Hardin
Reference: Specification & CQA Plan Revision Recommendations
Marshall Steam Station Issue No. MAR-131
Terrell, NC
S&ME Project No. 7235-16-004
NC PE Firm License No. F0176
Dear Mr. Baucom and Ms. Hardin:

Geocomposite Selection Verification of Physical Properties
For geocomposite selection verification, S&ME recommends a transmissivity testing frequency of one test
per 540,000 square feet (1/540,000 sf) or 1/lot be performed using the actual materials for the interface.
This transmissivity result should meet the requirements as stated in Table 02675-C in specification section
02675. Conformance transmissivity testing by the CQA firm as identified in Section 02675, 1.5 D, should
be changed from 1/100,000 sf to 1/540,000 sf or 1/lot. This frequency is being revised to be consistent
with the manufacturer’s quality control (MQC) testing frequency. Typically conformance testing is
performed as a CQA check of the MQC testing, and it is not performed more frequently than MQC testing.

Hydraulic Conductivity Ratio Testing
Hydraulic Conductivity Ratio (HCR) Testing ASTM D 5567 is only required for the upper geotextile of the
geocomposite. It is not required for woven geotextile or non-woven geotextile used outside of the
landfill leachate collection system.
Geosynthetic Clay Liner (GCL)
As detailed in the Duke Construction Modification Request letter dated October 23, 2016, testing was
performed during the bid document development phase to prequalify GCL materials for long-term
hydraulic conductivity compatibility with the site-specific leachate through ASTM D6766 testing with
various GCL samples from various manufacturers. Pre-qualification testing was primarily being performed
Specification & CQA Plan Revision Recommendations
Marshall Steam Station Issue No. MAR-131
Terrell, NC
S&ME Project No. 7235-16-004

April 7, 2017 2
early on in the process due to the duration of time to perform the testing and meet the testing
termination criteria. Three GCL materials were pre-qualified during this initial testing - all of which
needed polymer enhancement to meet the hydraulic conductivity requirements for long-term
compatibility. Testing durations ranged from about 3.5 to 5 months. Charah (the general contractor for
Cells 3 & 4 construction) proposed to use one of the pre-qualified GCL materials - Agru America's
GeoClay NN66-7E (polymer enhanced) GCL. The ASTM D6766 pre-qualification test results for the
material are attached for reference. Since the GCL selected for construction project has been pre-
qualified with site-specific leachate hydraulic conductivity testing, in accordance with ASTM D6766; this
testing is proposed to be removed from the CQA Plan and specifications for both manufacturer's quality
control (MQC) and conformance testing. However, hydraulic conductivity testing (permeability testing
with water) in accordance with ASTM D5887 will be performed as part of manufacturer's quality control
(MQC) and conformance testing.
S&ME recommends changing the GCL Index Flux (ASTM D 5887) conformance testing frequency from 1
test per 100,000 square feet to 1 test per 270,000 square feet in the in the CQA Plan and specifications.
This frequency is being revised to be consistent with the manufacturer’s quality control (MQC) testing
frequency. Typically conformance testing is performed as a CQA check of the MQC testing, and it is not
performed more frequently than MQC testing.

As requested in DEQ Solid Waste's previous approval letter of construction modifications dated October
28, 2016, the project changes will be captured in the final Cells 3 & 4 construction quality assurance
documentation to be submitted for a Permit to Operate of Cells 3 & 4.

Sincerely,

S&ME, Inc.

Sharon Y. Korleski, PE Stephen J. Loskota, PE
Senior Engineer Senior Engineer

cc: Tyler Hardin, Duke Energy
Leo Furlong, Duke Energy

Attachments: Pre-Qualification ASTM D6766 Test Results for Selected GCL Material

Attachments