9. GEOMEMBRANE MANUFACTURING, TRANSPORTATION, AND STORAGE
9.1 High Density Polyethylene Geomembrane Manufacturing
The geomembrane shall be manufactured from a medium
or high density polyethylene resin. Only one type of resin (one manufacturer,
one resin classification) shall be used to manufacture geomembrane
for this project.
9.1.1 Raw Material
The raw material will be first quality polyethylene
resin containing no more than 5% clean post-industrial (edge trim)
recycled polymer by weight, and meeting the following specifications:
| This is the industry standard. It is very difficult to
analyze the amount of recycled polymer being used, although
dirty badly degraded material could be detected. The use
of post-industrial material (edge trim etc.) presents little
concern, but post-consumer recycled material should not be
used. In the gas pipe industry HDPE is regularly made with
up to 10%, and even 100%, of clean recycled material, without
loss of performance. |
- Specific Gravity (ASTM D792 Method A or ASTM D1505):
>0.930 (without carbon black);
| The specific gravity of the geomembrane, with carbon black,
should exceed 0.940. 1% of carbon black adds approximately
0.005 to specific gravity value. |
- Melt Index (ASTM D1238 (190/2.16)): 0.05 - 1.0; and
- Stress Rupture Transition Time (ASTM
D5397): > 200 hr
|
The stress rupture transition time should be an absolute
minimum of 100 hr as specified in GRI-GM13 and could be
as high as 600 hr or more depending on the criticality
of the installation, the likely amount of installation
damage, and the service conditions. There are presently
only a few HDPE resins with transition times exceeding
5000 hr. In 1993, the stress rupture resistance of commercially
available HDPE geomembranes varied by a factor up to 1000.
Making this the single most important durability parameter
for the different HDPE resins.
|
Quality Control certificates issued by the Resin Manufacturer
shall be presented by the Installer to the CQA Consultant to show
that these specifications have been met and to identify the type
of resin.
Internal Quality Assurance testing will be carried
out by the geomembrane Manufacturer to demonstrate that the incoming
resin meets this specification. At the Owner's discretion, additional
conformance testing, paid for by the Owner, may be carried out at
the CQA Laboratory. If the results of the Manufacturer's Quality
Control (QC) Laboratory and the CQA Laboratory testing differ, the
testing will be repeated by the CQA Laboratory, and the Manufacturer
will be allowed to monitor this testing. The results of this latter
series of tests will prevail, provided that the applicable test methods
have been followed.
Prior to the installation of any geomembrane material,
the Manufacturer will provide the Project Manager and the CQA Consultant
with the following information:
- The origin (resin Supplier's name), identification (type,
lot number), and production date of the resin;
- a copy of the Quality Control certificates issued by the Resin
Supplier;
- reports on the tests conducted by the Manufacturer to verify
the quality of the resin used to manufacture the geomembrane
rolls assigned to the project. At a minimum, these tests should
include specific gravity (ASTM D792 Method A or ASTM D1505),
and Melt Index (ASTM D1238 (190/2.16)); and
- a statement that no post-consumer recycled polymer has been
added to the raw resin. However, the use of clean post-industrial
polymer recycled during the manufacturing process may be permitted
if done with appropriate cleanliness and if recycled polymer
does not exceed 5% by weight).
The CQA Consultant will review these documents and
report any discrepancies to the Project Manager.
9.2 Geomembrane Plant Audit
| A Plant Audit and pre-delivery conformance testing are
extremely beneficial if a large amount of material is being
purchased or if it is being shipped long distances, when
major delays could result if unsatisfactory material is discovered
after delivery at the site. |
9.2.1 Scope
The CQA Consultant shall (you
may wish to say "may",
thus leaving the option open) perform an audit of the manufacturing
and quality control procedures used by the Manufacturer specifically
for the production of the HDPE geomembrane to be used for installation
at the Owner's facility. The Manufacturer shall give the CQA Consultant
at least 48 hours notice of the start of production of geomembrane
for this project. The Owner has the right to refuse acceptance of
any geomembrane manufactured within this 48 hr period if his representative
is not present. QC tests shall be performed as the geomembrane is
manufactured.
9.2.2 Quality Control
The Manufacturer shall make available to the Owner
and CQA Consultant Manufacturing Quality Control manuals which outline
all quality procedures which will be implemented for the manufacture
of the HDPE geomembranes.
The Manufacturer shall provide valid calibration certificates
for laboratory testing equipment.
The CQA Consultant shall verify that, during select
runs of material, all MQC procedures are performed.
9.2.3 Manufacturing Process
In general, the Manufacturer shall provide access for
the CQA Consultant to all equipment used to manufacture the HDPE
geomembrane. This does not include divulging trade secrets, additive
formulations, and procedures which are not commonly known as basic
manufacturing processes used for HDPE geomembranes. However, if the
process is critical to the integrity of the manufactured geomembrane,
the equipment shall be made accessible to the CQA Consultant.
The CQA Consultant shall monitor production and testing
of geomembrane material allocated for this project. If material for
this project has already been manufactured, the CQA Consultant shall
monitor production of the same type of geomembrane on the same production
line to verify that manufacturing controls are in place. The Manufacturer
shall provide raw resin QC certificates, resin QA test results, and
manufactured geomembrane QC certificates to the CQA Consultant prior
to the loading and shipping of geomembrane to the site. The CQA Consultant
shall immediately review the QC certificates and notify the Manufacturer
in writing which geomembrane rolls are approved for shipping. The
CQA Consultant shall be allowed to monitor the loading of the geomembrane
for shipping.
| You may wish to require the CQA Consultant to sign off
the QC test results or certificates, to indicate that such
testing has been satisfactorily performed. This could reduce
the amount of conformance testing that is required. |
9.3 Manufacturing
9.3.1 Submittals
Prior to the installation of any geomembrane, the Manufacturer
will provide the Project Manager and the CQA Consultant with the
following:
- A certified properties sheet including, at a minimum, all
specified properties, and test methods indicated in the specifications;
- A list of quantities and descriptions of materials other than
the base polymer which comprise the geomembrane; and
- The internal MQC sampling procedures, frequencies of testing,
and results of testing of material supplied to the project.
The CQA Consultant will verify that:
- the property values certified by the Manufacturer meet all
of the Manufacturer's specifications; and
- the measurements of properties by the Manufacturer are properly
documented, the test methods used are acceptable, and the geomembrane
meets the Project Specifications.
9.3.2 Rolls
Prior to shipment, the Manufacturer will provide the
Project Manager and the CQA Consultant with Quality Control certificates
covering each roll of geomembrane and welding rod provided. (NOTE:
Tests do not have to be done on each roll, they simply need to be
done according to an agreed upon frequency, usually defined in the
Manufacturer's QC plan.) The Quality Control certificate will be
signed by a responsible party employed by the Manufacturer, preferably
the QC Laboratory Manager. The Quality Control certificates will
include:
- resin Manufacturer, resin type, resin lot number, and geomembrane
roll numbers; and
- results of Quality Control tests. At a minimum, results will
be given for thickness, specific gravity/density, uniaxial tensile
strength and elongation at yield and break, single point stress
rupture time, and carbon black content and dispersion, evaluated
in accordance with the methods indicated in the specifications
or equivalent methods previously approved by the Project Manager
and CQA Consultant. No material will be installed until complete
QC test data have been provided.
You may wish to require that no material shall be shipped
from the plant until all QC data have been received. This can be
difficult to achieve in practice.
The CQA Consultant will:
- verify that the Quality Control certificates have been provided
at the specified frequency for all rolls, and that each certificate
identifies the rolls and resin related to it; and
- review the Quality Control certificates and verify that the
certified roll properties meet the Manufacturer's and Project
Specifications.
9.3.3 Conformance Testing
Conformance testing is not an opportunity to reproduce
the QC testing program, but is simply a spot-check to provide confidence
that satisfactory material is delivered to the site.
Conformance Testing will, ideally, be performed before
material is shipped from the Manufacturer's plant so that it may
confidently be used immediately on arrival at the site. However,
in many cases it is done when material arrives on the site.
9.3.3.1 In-Plant testing
The purpose of In-plant Material Conformance Test Sampling
is to verify that geomembrane material which is designated for the
Owner's project is confirmed as meeting the project specifications
prior to shipment to the site. Thus, barring a transportation accident,
the geomembrane can be installed immediately it arrives on site.
The Manufacturer will make available all necessary
personnel and equipment to assist the CQA Consultant in retrieving
conformance samples of the geomembrane material.
The CQA Consultant shall send to the CQA Laboratory
conformance samples for testing as outlined in Section 9.3.4. The
frequency of sampling shall be at the discretion of the CQA consultant
but shall typically be between each 10,000 and 25,000 m2 of geomembrane.
No material shall be shipped to the site until conformance test results
are obtained.
The CQA Consultant shall report any nonconformance
of sampling procedures as outlined in Section 9.3.8 to the Project
Manager.
9.3.3.2 On-site material testing
If In-Plant conformance testing is not performed, upon
delivery of the rolls of geomembrane to the site, the CQA Consultant
will ensure that samples are removed at the frequency specified in
the Project Specifications (or at the rate shown in Table 1 if not
specified) and forwarded to the CQA Laboratory for testing to ensure
conformance to both the Project Specifications and the Manufacturer's
list of guaranteed properties.
9.3.3.3 Properties of the HDPE Geomembrane
In the absence of any Project Specifications, the HDPE
geomembrane shall meet the specifications shown in Table 1.
TABLE 1. HDPE GEOMEMBRANE SPECIFICATIONS AND CONFORMANCE
TESTING FREQUENCY
| PARAMETER |
METHOD |
VALUE |
CQA TEST FREQUENCY |
| Average Thickness |
ASTM D751* |
> nominal value |
each roll |
| Minimum Thickness |
ASTM D751* |
90% nominal value |
each roll |
| Density (g/cm3) |
ASTM D1505ASTM D792 |
> 0.940 |
10,000 m2 |
| Melt Index (g/10 min) |
ASTM D1238(190/2.16) |
0.05 - 1.0 |
25,000 m2 |
| Tensile Properties |
ASTM D638 (IV)* |
|
|
| |
Yield Stress (MPa [psi]) |
|
>15.2 [2200] |
N/A |
| Yield Strain (%) |
> 12 |
N/A |
| Break Stress (MPa [psi])* |
> 20.7 [3000] |
10,000 m2 |
| Break Strain (%)* |
> 600 |
10,000 m2 |
| Tear Resistance (kN [lb]) |
ASTM D1004 |
> 1.02 [230] |
N/A |
| Puncture Resistance (kN [lb]) |
FTMS 101C Method 2065 |
> 1.89 [425] |
N/A |
| Dimensional Stability (%) |
ASTM D1204
1 hr at 100ºC
|
< 2.0 |
N/A |
| Carbon Black Content (%) |
ASTM D1603 |
2.0 - 3.0 |
10,000 m2 |
| Carbon Black Dispersion |
ASTM D2663 (B) ASTM D5596 |
A1, A2, B1 |
10,000 m2 |
| Stress Rupture TransitionTime (hr)* |
ASTM D5397 |
> 200 |
N/A |
| Stress Rupture Break Time - Single point (hr)* |
GRI.GM5 (b) |
> 300 |
N/A |
|
* The thickness of textured sheet
may be measured with a pointed tip micrometer - tip radius
0.75 m, tip angle
60°. Optical examination of cross sections offers another
(preferred) method of measuring thickness of textured materials.
The uniaxial break strength and elongation will vary depending
upon the method of texturing. Textured blown film geomembrane
will have lower values than secondary process, thermally
bonded, textured materials which generally have similar
values to smooth materials. For textured and structured
materials, the measurement of stress rupture resistance
must include the influence of the surface profile, thus
notched specimen tests are not appropriate. Having confirmed
that the basic resin has adequate stress rupture performance,
perform a constant load test on an unnotched strip specimen,
10 mm wide, at 80°C and at a stress of 4 MPa. Repeat
the test on the textured/structured material, the latter
including the surface profile features. The failure time
of the textured/structured specimen(s) should not be less
than ____ hr. Seams can be treated the same way.
|
9.3.4 Conformance Tests
At a minimum, tests to determine the following parameters
will be performed on HDPE geomembranes:
- density/specific gravity;
- carbon black content and dispersion;
- uniaxial tensile break strength and elongation; and
|
There is no need to perform the following conformance
tests, provided the same quality control tests have been
performed and reported:
- dimensional stability
- tear resistance
- puncture resistance
- uniaxial strength and elongation at yield, and
- notched constant tensile load stress rupture
There is no need to perform ESCR tests (ASTM D1693) at
all - this test does not provide useful information. There
is no need to perform Low Temperature Brittleness (LTB)
tests (ASTM D746).
|
9.3.5 Test Procedures
The following test procedures will be complied with:
- density: ASTM D792-66 Method A or ASTM D1505;
- melt index: ASTM D1238 (190/2.16);
- carbon black content: ASTM D1603;
- carbon black dispersion: ASTM D2663 (B) or ASTM D5596;
- thickness: ASTM D1593 or ASTM D751 for smooth and structured
geomembranes; optical method for textured geomembranes;
- uniaxial tensile properties: ASTM D638 (IV) with no requirement
for sample conditioning time.
Where optional procedures are noted in the test method,
the requirements of the Project Specifications will prevail.
9.3.6 Sampling Procedures
Samples will be taken across the entire width of the
roll and will not include the outer wrap of the roll. Unless otherwise
specified, samples will be 500 mm long by the roll width. Specimens
for testing will be taken across the full width of the sample.
If more than one resin type is used, each resin type
shall be sampled at the same frequencies and tested.
If roll numbers are very different and non-sequential,
consideration should be given to testing each block of roll numbers
at the same frequency.
| If adequate QC testing is performed by the Manufacturer
it is not necessary to perform conformance testing at higher
frequencies. |
9.3.7 Test Results
The CQA Consultant will examine all results from laboratory
conformance testing and will report any nonconformance to the Project
Manager.
The following procedure will apply whenever a sample
fails a conformance test that is conducted by the CQA Laboratory:
- The Manufacturer will replace the roll of geomembrane that
is in nonconformance with the specifications with a roll that
meets specifications.
- The CQA Site Superintendent will remove conformance samples
for testing by the CQA Laboratory from the next higher and lower
numbered rolls. These two samples must both conform to specifications.
If either of these samples fail, testing shall continue until
the defective rolls are isolated. These rolls will be replaced
by the Manufacturer, at no expense to the Owner. This additional
conformance testing will be at the expense of the Manufacturer.
The CQA Consultant will document actions taken in conjunction
with conformance test failures.
9.4 Delivery
9.4.1 Transportation and Handling
Transportation of the geomembrane is the responsibility
of the Manufacturer, Installer, or other party as agreed upon. All
handling on-site is the responsibility of the Installer.
The CQA Consultant will verify that:
- handling equipment used on the site is adequate and does not
pose any risk of damage to the geomembrane particularly to the
edges of the geomembrane; and
- the Installer's personnel handle the geomembrane with care.
Upon delivery at the site, the Installer and the CQA
Consultant will conduct a visual examination of all rolls for defects
and signs of damage. This examination will be conducted without unrolling
rolls unless defects or damage are found or suspected. The CQA Consultant
will indicate to the Project Manager:
- any rolls, or portions thereof, which should be rejected and
removed from the site because they have unacceptable flaws; and
- any rolls which contain minor repairable flaws.
9.4.2 Storage
The Installer will be responsible for the storage of
the geomembrane on-site. The Project Manager will provide storage
space in a location (or several locations) such that on-site transportation
and handling are minimized. Geomembrane rolls will be stored on a
smooth, dry, level surface in an area where the geomembrane, particularly
the roll edge, is protected from damage. Rolls, particularly textured
rolls, will not be allowed to get dirty.
The CQA Consultant will verify that storage of the
geomembrane ensures adequate protection against dirt, impact, and
other sources of damage.
Rolls will not be stored more than 3 high. Access will
be provided to each end of stored rolls for the examination of identification
labels and roll edges.