Geosynthetics October/November 2020 - 19

Case Study

CCR landfill final cover
test pad-Part 2
By Nina J. Balsamo, John Massey-Norton, John R. Klamut, Terry Queen,
Charles F. Straley and Mark R. Lehner

n integrated drainage system (IDS) geomembrane, which provides both a lowpermeability membrane and drainage space above the geomembrane, is being
used in the final cover at a coal combustion residuals (CCR) landfill in West Virginia.
Part 1 of this article, in the August/September 2020 issue of Geosynthetics magazine,
presented construction of the test pad to evaluate 1-inch (2.5-cm) maximum subgrade protrusions beneath the geomembrane, placement of cover soil with a 9-inch
(22.9-cm) maximum particle size using a low ground pressure (LGP) dozer, and the
evaluation of the geosynthetics in 2016. Part 2 of this article presents the application
of heavy traffic loads over the benched portion of the test pad to evaluate its use as
a temporary haul road (in 2016), and additional exhumation of the test pad in 2018.

PROJECT HIGHLIGHTS
COAL COMBUSTION
RESIDUALS TEST PAD
DESIGN ENGINEER

GAI Consultants Inc.
GEOSYNTHETICS PRODUCTS

Agru Super Gripnet® 50 mil
HDPE liner and AgruTex 081
nonwoven geotextile
GEOSYNTHETICS MANUFACTURER

Test pad subareas
As presented in Part 1, AGRU Super Gripnet 50-mil (1.27-mm) high-density polyethylene (HDPE) liner and AgruTex 081 nonwoven geotextile were incorporated
into a landfill final cover system. To evaluate various conditions, a test pad divided
into several subareas was constructed. The subgrade protrusion height, cover soil
lift thickness, cover soil maximum rock size and subareas with cushion geotextile
are listed in Table 1 on page 20. Test conditions for adjacent Subareas C and E were
identical, and test conditions for adjacent Subareas D and F were identical.
To evaluate the effect of subgrade protrusions, the American Association of State
Highway and Transportation Officials (AASHTO) No. 57 angular, crushed stone
aggregate and one larger rock were placed within each subarea to create approximate
1-inch (2.5-cm) protrusions. The geomembrane and geotextile were installed, and 18
inches (45.7 cm) of soil was placed over each subarea using an LGP dozer.
Presuming construction equipment may need to utilize the benches of the completed final cover for access, a temporary access road investigation was performed.
The investigation consisted of the placement of an additional 18 inches (45.7 cm)
of cover soil (3 feet [0.9 m] total) on the lower test pad bench, then trafficking the
bench with a fully loaded 45-ton (40.8-tonne) articulated truck. Half of the bench

Agru America Inc.

Nina J. Balsamo, P.E., is a senior project
engineer at GAI Consultants Inc. based
in Pittsburgh, Pa.
John T. Massey-Norton is a retired
hydrogeologist at a major electric
utility company.
John R. Klamut, P.E., is a senior project
manager with GAI based in Pittsburgh, Pa.
Terry Queen is senior lead construction
technician with GAI based in Charleston, W.V.
Charles F. Straley, P.E., P.S., is a senior
engineering manager at GAI based in
Charleston, W.V.
Mark R. Lehner, P.E., is a senior engineering
manager at GAI based in Pittsburgh, Pa.
All figures courtesy of the authors

www.GeosyntheticsMagazine.com

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9/22/20 12:51 AM

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Geosynthetics October/November 2020

Table of Contents for the Digital Edition of Geosynthetics October/November 2020