HomeMy WebLinkAboutPSD-047-06
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REPORT
PLANNING SERVICES
Meeting: GENERAL PURPOSE AND ADMINISTRATION COMMITTEE
Date: Monday, April 24, 2006
Report #: PSD-047-06
File #: PLN 33.4
By-law #:
Subject: PORT GRANBY PROJECT - UPDATE ON ENHANCED FACILITY DESIGN
AND REVISED ENVIRONMENTAL ASSESSMENT STUDY REPORT
RECOMMENDATIONS:
It is respectfully recommended that the General Purpose and Administration Committee
recommend to Council the following:
1. THAT Report PSD-047-06 be received for information, and
2. THAT a copy of Council's decision be forwarded to all interested parties indicated in this
report.
Submitted by:
Reviewed b}t ) ~ c 9 ~ e. It.
Franklin Wu,
Chief Administrative Officer
a . Crome, M.C.I.P., R.P.P.
Director of Planning Services
JAS/FLlDJC/df
7 April 2006
CORPORATION OF THE MUNICIPALITY OF ClARINGTON
40 TEMPERANCE STREET, BOWMANVILLE, ONTARIO L 1C 3A6 T (905)623-3379 F (905)623-0830
REPORT NO.: PSD-047-06
PAGE 2
1.0 BACKGROUND AND PURPOSE OF REPORT
1.1 On March 29, 2005, Committee adopted a resolution to request the Low Level
Radioactive Waste Management Office (LLRWMO) investigate the effects of installing a
double composite base liner at the new Long Term Waste Management Facility (L TWMF)
for the Port Granby Project, and to revise the Environmental Assessment Study Report
(EASR) accordingly.
1.2 On January 23, 2006, Mr. Glenn Case of the LLRWMO made a presentation to
Committee to advise that their investigation had indicated the installation of a double liner
would not appreciably improve the safety performance of the L TWMF. Mr. Case also
indicated that, as a result of a comprehensive review of the entire facility design, the
LLRWMO was recommending that the performance of the mound be enhanced through
the incorporation of a capillary drainage layer into the mound cover. Staff indicated their
support for the LLRWMO's recommendation through Report PSD-007-06, as did the
Municipal Peer Review Team (MPRT) through their peer review report.
1.3 Mr. Sarwan Sahota and Mr. John Stephenson of the South East Clarington Ratepayers
Association (SECRA) made presentations to Council on January 30, 2006 in respect of
the revised facility design for the Port Granby Project. Council referred subsequent
correspondence from the LLRWMO (February 27, 2006 Council) and Mr. Stephenson
(March 20, 2006 Council) to the Planning Services Department. A letter from Mrs. Cathy
McNeill was also received by Council on April 18, 2006 and referred to Planning.
1.4 The MPRT has prepared a revised peer review report in respect of the enhanced facility
design for the Port Granby L TWMF (see Attachment 2). This report provides more
detailed information regarding the operation of the capillary drainage layer, and explains
the MPRT's rationale for supporting the enhanced facility design as recommended by the
LLRWMO in lieu of a double base liner system. This report also provides the MPRT's
recommendations for further optimizing the performance of the enhanced mound cover.
1.5 The purpose of this staff report is to provide an overview of the MPRT's position with
respect to the design of the L TWMF, to respond to specific questions and issues raised
by both Council and residents, and to advise Council with respect to the status of the
revised EASR.
2.0 PEER REVIEW TEAM POSITION REGARDING DESIGN OF THE L TWMF
2.1 The base liner system of the L TWMF is required to deal with leachate generated during
the construction phase when precipitation will contact the waste, and in the early
operational life of the mound due to any residual moisture from construction activities.
Leachate generation after this period is expected to be negligible.
2.2 The MPRT's recommendation for a double liner system in March 2005 was based on
the uncertainty of the durability of the geomembrane components in both the cover and
liner systems, which are required to effectively minimize and contain any leachate in the
long term. This was of particular concern in the event of the failure of the geomembrane
REPORT NO.: PSD-047-06
PAGE 3
in the cover system, which would increase the potential for leachate generation. Under
such a scenario, the native till under the mound would have been relied on to provide
redundant containment of the leachate in order to protect the surrounding environment
should the geomembrane in the liner system also fail. Although the native till could be
expected to contain any leachate that escaped the mound, it was the MPRT's position
that any scenario that involved any contamination of the till layer was unacceptable
because of the potential for environmental contamination.
2.3 Subsequent to the LLRWMO's review of several double liner systems and the
conclusions that a second liner would not appreciably improve the performance of the
mound, the MPRT and the LLRWMO agreed that a comprehensive review of the entire
facility design was needed to assure isolation of the waste from the environment.
2.4 The enhanced facility design for the engineered mound developed by the LLRWMO as
a result of this review utilizes a capillary barrier and drainage system as part of the
cover system. This system would provide further protection from moisture contacting
the waste and would further reduce the potential for leachate generation to negligible
levels, even in the event of a failure of the geomembrane in the cover system. As well,
the capillary drainage system would be composed of natural materials, would operate
passively, and would contain instrumentation to detect moisture infiltration. The mound
cover could also be repaired if the sensors that are embedded within the capillary
drainage system detected any moisture infiltration.
2.5 To assess the appropriateness of the LLRWMO's conclusions, the MPRT reviewed
background documentation on industry experience with respect to capillary barriers, as
well as the preliminary conceptual details of the proposed cover system. The MPRT
also had technical meetings with the LLRWMO and its technical consultant to discuss
the proposed design. Based on this review, the MPRT has concluded that the enhanced
facility design meets their expectations with regard to environmental performance. By
effectively reducing the amount of moisture contacting the waste to negligible levels,
even in the case of the degradation of the geomembrane component of the cover
system, there will be less reliance on the liner system to manage the leachate and
protect against soil and groundwater contamination.
2.6 The MPRT is satisfied that the enhanced cover design improves the overall
performance of the L TWMF and provides Clarington residents and Council with a state-
of-the-art facility and an increased level of confidence. In particular, the enhanced
design meets the key objectives the MPRT originally sought by recommending a double
liner in the original facility design - i.e. protecting the underlying till, preventing potential
leachate contamination of groundwater, and providing redundancy in the facility design.
As such, it is the opinion of the MPRT that, with the enhanced facility design, a double
liner system is no longer necessary.
2.7 A full discussion of the MPRT's review of the enhanced facility design is provided in
Section 2 of the MPRT's report. The MPRT has also made a number of
recommendations to the LLRWMO on ways in which the capillary barrier concept could
be enhanced. The LLRWMO is actively studying these recommendations and has
REPORT NO.: PSD-047-06
PAGE 4
already incorporated a number of these recommendations into the facility design. The
MPRT's recommendations are set out in Section 3 of their report.
3.0 RESPONSE TO ISSUES RAISED BY COUNCIL AND RESIDENTS
3.1 Possible tearino of base liner durino construction
3.1.1 The single base liner system for the L TWMF will consist of the following three
components (from top to bottom):
. 0.5 m thick sand layer which houses the leachate collection system and which
provides a permeable media through which the leachate will preferentially travel;
. 0.002 m thick High Density Polyethylene (HOPE) geomembrane to provide a bottom
to the sand layer and to assist in the collection of the leachate;
. 0.75 m (2.4 ft) thick compacted clay liner (CCL) to adsorb and further repel any
leachate that may migrate through the two previous component layers.
This single three component base liner system would be 1.25 m (4.1 ft) thick, with each
component performing a specific function and providing a redundant level of protection.
3.1.2 The concern noted by Council and residents relates to the possible tearing of the HOPE
geomembrane during construction of the liner system and during waste placement.
There are a number of operational controls used to protect the geomembrane that have
proven to be effective over many years of experience. These include preparation of the
underlying CCL to ensure it will provide a proper base for the geomembrane, and
inspection of the geomembrane to ensure that there are no foreign objects (i.e. rocks) that
could puncture the membrane. The seams of the geomembrane are fused together to
create a watertight barrier. This fusing process is subject to stringent inspection and
quality control. Once the entire geomembrane has been installed, it is tested for leaks.
3.1.3 No machinery ever comes in direct contact with the HOPE geomembrane in the liner
system. During the installation of the liner, a 0.3 m (1 ft) cushion of sand will be placed
over the geomembrane to support the equipment. The HOPE is installed using track-
mounted equipment.
During placement of the waste, the 0.5 m (1.6 ft) thick sand leachate collection layer
will provide protection to the geomembrane. As a further precaution, the first 0.5 m lift of
waste placed over the sand layer will be select material. Trucks hauling the first few lifts
of waste into a cell will be restricted to internal temporary haul roads so that there is at
least a 1 m separation between the truck tires and the geomembrane liner. The initial lifts
of waste will be spread by a low ground pressure tracked bulldozer (35 kPa max. ground
pressure).
REPORT NO.: PSD-047-06
PAGE 5
The liner installation and waste placement processes will be continuously supervised to
ensure the integrity of the membranes.
3.2 Failure of a sino Ie base liner durino ooeration of the L TWMF
3.2.1 This concern also seems to relate to the possible failure of the HOPE geomembrane
component of the three component base liner system. The base liner system of the
L TWMF is primarily required to deal with leachate created during construction, when the
waste is exposed to precipitation, and in the 5 to 10 year period following construction of
the mound when residual drainage of leachate will occur. After this period, leachate
volumes will be reduced to negligible levels - less than 3 litres per day (1 cu. m. per year)
produced from pre-existing moisture in the waste since the enhanced mound cover will
ensure that no precipitation will contact the waste.
3.2.2 Testing and field experience with HOPE geomembranes has indicated that they have a
life expectancy of several hundred years. Specifically, HOPE geomembranes are
manufactured with anti-oxidant compounds to inhibit chemical oxidation of the polymer.
Standardized chemical compatibility testing has indicated that the performance of the
HOPE geomembrane will not be compromised by exposure to chemicals in the leachate.
3.2.3 However, in the event that the geomembrane in the liner unexpectedly deteriorates, the
0.75 m thick compacted clay liner (CCL) beneath the geomembrane will act as a very
effective barrier to leachate. Since the CCL is comprised of natural materials, its function
as a barrier to the minimal volumes of leachate that will be generated will not diminish
during the life of the L TWMF.
3.2.4 The LLRWMO's review of the efficiencies of liner systems indicated that a single liner
system would contain 99.95% of the leachate, while a double liner would contain 99.99%
of leachate. Given that leakage rates for the single liner system are predicted to be
barely measurable (less than 0.01 mm per year), the 0.45% increase in leachate
containment afforded by a second liner system would not represent an improvement in
the performance of the L TWMF.
3.2.5 Even under a scenario involving a complete failure of the geomembrane in the mound
cover, the redundant protection provided within the cover would capture virtually all of the
moisture, so that less than 0.01 % of the precipitation would contact the waste. Again, this
very low rate of leachate production (less than 0.08 mm per year) is easily handled by a
single liner system, even in the event of a complete failure of the geomembrane in the
liner system. The mound cover could be repaired if sensors installed in the cover system
detect any failures, while the liner system cannot be repaired.
3.3 A double liner system was reiected because of cost
3.3.1 The single base liner system under the L TWMF is expected to cost $4.75 million. The
additional cost for the three options for doubling the liner investigated by the LLRWMO
ranged from $2.81 million to $4.75 million. The LLRWMO's analysis indicated that none
of these options would perform appreciably better than the single three component base
liner. Since no significant groundwater quality impacts are expected with the single base
REPORT NO.: PSD-047-06
PAGE 6
liner system, the installation of a second base liner system would not provide any
significant technical advantage. As such, the doubling of the base liner was rejected not
because of cost, but because it did not enhance the redundant level of protection.
3.3.2 The capillary drainage layer in the mound cover will be constructed using the native till
already found on the site of the future L TWMF. The soil fractions in the till (ie. gravel,
sand, silt and clay) will be separated on-site. The availability of suitable soil on-site will
preclude the need to transport the soil materials needed for the capillary barrier along
area roads. The additional cost related to the construction of the capillary drainage layer
in the mound cover is approximately $1.03 million.
3.3.3 In the opinion of both the LLRWMO and the MPRT, the proposed enhancement to the
mound cover through the incorporation of a capillary drainage layer provides a much
more cost effective and pro-active approach to environmental protection than the
construction of a double liner system. The construction of the capillary drainage barrier in
the mound cover renders a double line system unnecessary because it reduces the
volume of leachate that the liner system would have to deal with to negligible levels. As
well, the construction of an enhanced cap would involve no increase in project-related
truck traffic and a significantly shorter increase in the duration of the Project than would
the construction of a double liner.
3.3.4 In the opinion of both the LLRWMO and the MPRT, the capillary drainage barrier provides
the redundant level of protection that the Municipality was seeking through their request
to examine a double liner system.
3.4 The Port Hope L TWMF will include a double base liner svstem and a capillary drainaae
laver
3.4.1 The design of both the Port Granby and Port Hope L TWMFs has been tailored to address
the specific geotechnical characteristics of each site. Given the significant differences
between the two sites, it is not appropriate to compare specific design elements.
3.4.2 The bottom of the Port Granby mound will be located between 5 to 20 m above the water
table and will be underlain by 8 to 12 m of relatively impermeable native till, which will
provide a very stable base for the mound. In contrast, the relatively porous soils found
at the Port Hope site do not provide as stable a base for the mound and the water table is
in relatively close proximity to the bottom of the mound. These characteristics necessitate
the installation of a double liner system at the Port Hope facility.
3.5 Installation of a double liner svstem would enhance health and safetv and public
confidence in the L TWMF
3.5.1 It is the opinion of both the LLRWMO and the MPRT that the enhanced facility design,
which incorporates a capillary drainage layer into the mound cover, together with the
three component base liner system, will ensure the isolation of the waste from the
environment. The installation of a double base liner would not improve the performance
of the mound in protecting the health and safety of residents. The MPRT is satisfied that
the enhanced cover design improves the overall performance of the L TWMF and provides
REPORT NO.: PSD-047-06
PAGE 7
Clarington residents and Council with a state-of-the-art facility and an increased level of
confidence.
3.5.2 It is also important to note that all aspects of the Port Granby Project, including a detailed
design of the L TWMF, will be subject to rigorous review by various federal and provincial
agencies, such as the Canadian Nuclear Safety Commission (CNSC), prior to the
approval of the EASR and the issuance of a construction license.
3.6 A second base liner svstem is needed because the waste will take a lono time to dry
3.6.1 After the mound is completed and the cap over the waste is constructed, leachate will
be generated from free water within the waste. Initial leachate production after the
mound is expected to be about 126 cu. m. per day (126 cu. m. per year). However, the
rate of leachate production will decline exponentially over the first few years, so that
within 10 years leachate production will reach a steady state of less than 0.003 cu. m.
per day (less than 1 cu. m. per year).
3.6.2 The waste within the mound will retain much of its original water content in tension and
this moisture will never drain out. It will also not evaporate because of the 3.5 m thick
mound cover overtop of the waste.
3.7 The use of capillary drainaoe lavers is not wide-spread and is onlv experimental
3.7.1 The MPRT undertook a review of the use of capillary barriers at other waste facilities.
This review indicated that capillary barriers are used in a number of waste sites to prevent
precipitation from contacting the waste. For example, a capillary-based barrier has been
installed and has been operational since 1994 at the Hanford Superfund radioactive
waste site in Washington State. This system has been found to operate satisfactorily in a
temperate/humid environment similar to Ontario.
3.7.2 The use of capillary barriers in hazardous landfills and for the remediation of waste sites
is increasing due to the advantages such barriers provide. Key advantages include their
ability to retain and divert water, and their constructability using natural materials and
configurations that imply longevity.
3.7.3 The MPRT'S review found that the mound cover proposed by the LLRWMO for the Port
Granby L TWMF, with the capillary barrier and the HOPE geomembrane, is more robust
than most of the cover systems used at other waste sites.
A more detailed discussion of the history and use of capillary barriers is provide in Section
2.1 and Appendix A of the MPRT report.
3.8 The capillary drainaoe laver represents on Iv a maroinal improvement to the mound cover
3.8.1 The average annual precipitation in the Port Granby area is 820 mm. As indicated by
the following, virtually all precipitation that falls on the L TWMF will be collected and
drained away by the mound cover:
REPORT NO.: PSD-047-06
PAGE 8
. 500.2 mm (61 %) will be lost through evapo-transpiration (ie. the sum of
evaporation and transpiration by plants)
. 180.4 mm (22%) will be lost through runoff from the mound because of its sloped
sides; and
. 139.4 mm (17%) will infiltrate into the mound cover and be captured and drained
away by the sand drainage layer above the geomembrane.
Less than 0.01 % of the original 820 mm of precipitation (0.082 mm) is expected to
penetrate through the geomembrane in the cover. This minimal amount of moisture will
be captured by the capillary drainage layer and drained away from the waste to the
sides of the mound by capillary action. The net result is that the amount of moisture
available to reach the waste will be barely measurable.
3.8.2 In the unlikely event of a complete failure of the geomembrane in the mound cover, it is
anticipated that approximately 54 mm (7% of the incident precipitation) would leak
through the geomembrane into the capillary drainage layer. The capillary drainage
layer would drain away almost all of this moisture, again, less than 0.01 % of the original
incident precipitation (0.082 mm) would be available to contact the waste.
3.9 Double liners are commonly used in the U.S. for waste storaoe mounds
3.9.1 Hazardous waste sites in the United States tend to use generic mound designs that rely
on double base liners. In Canada, waste facilities tend to be designed to address the
specific characteristics of a site. The MPRT's review of non-hazardous and hazardous
waste sites in Canada, the United States and Europe indicated that the mounds with
double liners do not have enhanced caps. For example, the LLRW site at Weldon
Springs, Missouri, which contains 1.3 million cu. m. of Thorium-230 and Uranium
contaminated waste and soils, has a double base liner, but does not have a
geomembrane or a capillary barrier in the mound cover.
3.9.2 A more detailed description of the containment systems used at other waste sites is
provided in Appendix A of the MPRT report.
4.0 REVISED ENVIRONMENTAL ASSESSMENT STUDY REPORT
4.1 The LLRWMO has prepared a revised Draft EASR for the Port Granby Project, which
was received by Council at its meeting of April 3, 2006. A copy of the LLRWMO's letter
forms Attachment 3 to this report. In the letter, the LLRWMO indicates that Council's
objective in requesting a double liner in the new L TWMF was to increase confidence in
the long-term environmental safety of the new facility. However, the LLRWMO's
analysis indicated that the inclusion of a second base liner system did not enhance the
protective features of the mound to any significant extent, but could have a noticeable
effect on local residents through increased trucking and a longer construction period.
Further study indicated that the addition of a capillary drainage layer system to the
mound cover greatly increased the facility's ability to keep the wastes dry for the long
REPORT NO.: PSD-047-06
PAGE 9
term. This was found to be a much better design enhancement than incorporating a
double liner in the base of the facility.
4.2 The revised EASR is substantially the same as the document that was reviewed by the
MPRT and the public in the spring of 2005. The only substantive revisions relate to the
effects expected from the inclusion of the capillary drainage layer into the cover of the
L TWMF, and the construction of the grade separation under Lakeshore Road. As well,
some revisions have been made to reflect comments from the federal review of the
EASR for the Port Hope Project, which was submitted in April 2005.
4.3 The revised EASR is currently being reviewed by the MPRT. As well, copies of the
document have been provided to SECRA and are also available through the Clarington
Public Library. The review period will end on May 03, 2006. Given that the revised
EASR is substantially the same as the document submitted by the LLRWMO last year,
except for the changes noted above, this time period should be sufficient.
4.4 Any comments identified by the MPRT and the public during the review period will be
addressed by the LLRWMO in May. Any necessary revisions would be made to the
EASR and a final version of the EASR will be submitted to the June 5, 2006 Committee
meeting. Staff will also forward a report to the June 5, 2006 meeting with a
recommendation on whether Council should endorse the Project reflected in the EASR
as the Preferred Option for the Port Granby Project.
5.0 NEXT STEPS
5.1 Once Council endorses a Preferred Option, the LLRWMO will submit the EASR and all
other relevant documentation to the federal government for review. The following
federal and provincial agencies will be reviewing and providing comments on the EASR:
. Natural Resources Canada (NRCan)
. Department of Fisheries and Oceans
. Canadian Nuclear Safety Commission
. Canadian Environmental Assessment Agency
. Transport Canada
. Environment Canada
. Health Canada
. Ontario Ministry of the Environment
. Ontario Ministry of Transportation
. Ontario Ministry of Culture
. Ontario Provincial Police
5.2 Based on the experience with the Port Hope EASR, this review is expected to be quite
rigorous and detailed. The numerous technical reports prepared as part of the EA will
be scrutinized by the review agencies to ensure that the study methodologies used by
the LLRWMO and its consultants are appropriate and sufficiently comprehensive, and
that the conclusions of these studies are accurate. In particular, the design of the
L TWMF, including the single base liner system and the capillary drainage layer in the
REPORT NO.: PSD-047-06
PAGE 10
mound cover, will be reviewed to ensure that the storage mound will effectively isolate
the waste from the environment for several hundred years.
5.3 Once the review of the Port Granby Project EASR is completed, a draft Screening
Report will be issued by the federal authorities for review and comment. This report will
summarize the results of the federal/provincial review. Based on comments received,
the screening report will be finalized and a decision on whether to proceed with the
Project will be released by the federal government. Licensing by the CNSC will follow.
Currently, it is anticipated that the construction work related to the Port Granby Project
will commence in 2008.
6.0 CONCLUSIONS
6.1 Both Staff and the MPRT are pleased that the LLRWMO has worked so diligently over
the past year to address our concerns regarding the need to incorporate additional
redundancies into the design of the L TWMF for the Port Granby wastes. The MPRT
and staff are confident that the enhanced facility design, with the inclusion of the
capillary drainage layer into the mound cover and a three component base liner system,
represents a significant improvement to the design of the facility and makes the double
liner originally recommended by the MPRT technically unnecessary.
6.2 Nonetheless, Staff and the MPRT continue to be sensitive to the position expressed by
residents that a double base liner system is required at the L TWMF. Council's
endorsement of a Preferred Option for the Port Granby Project will allow the detailed
review of the L TWMF design by the federal and provincial review authorities to occur.
Attachments:
Attachment 1 - Glossary of Terms
Attachment 2 - Municipal Peer Review Team Report, March 2006
Attachment 3 - Letter from Glenn Case, LLRWMO, dated March 31,2006
REPORT NO.: PSD-047-06
PAGE 11
List of interested parties to be advised of Council's decision:
Ms. Sharon Baillie-Malo
Mr. Glenn Case, Director
Michael Ayer & Julie Jones
Vito Binetti
Wayne Boucher
Ray Coakwell and Frances Brooks
Rosemary Cooper
Marion and Stuart DeCoste
Frederic DeSourdy
Robert Edgar
Mel Edwards
Wilma Entwisle
Gord and Penny Ewington
Betty and Stephanie Formosa
Paulette Gerber
Lorri Graham
Walter Burham
Frank Hart
Luanne Hill
A. Karacsonyi
Susan Kinmond
Maria Kordas - Fraser
Jane Lawrence
Eric Leeuwner
Gerry Mahoney and Bonnie McFarlane
Andrew McCreath
Joanne McNamara
Office of Bev Oda, M.P.
Rupert McNeill
Lorri and Stuart Munro
Tim and Laurel Nichols
Dora Nichols
Carole Owens
Jean Payne
James B. Robertson
Ulrich Ruegger
Linda and Paul Ryerse
Sarwan Sahota
Barb Spencer
John Stephenson
Brian and Penny Stripp
Ken Shrives
Midori Tanabe
Brian Tayng
Harvey Thompson
Rosemary Tisnovsky
Stan Tisnovsky
Julie Tutla
Richard Walker
Mary and Harry Worrall
GLOSSARY OF TERMS
Attachment 1
To Report PSD-047-06
CCL
Compacted Clay Liner
CNSC
Canadian Nuclear Safety Commission
EA
Environmental Assessment
EASR
Environmental Assessment Study Report
GCL
Geosynthetic Clay Liner
HDPE
High Density Polyethylene
LLRW
Low Level Radioactive Waste
LLRWMO
Low Level Radioactive Waste Management Office
L TWMF
Long Term Waste Management Facility
MPRT
Municipal Peer Review Team
NRCAN
Natural Resources Canada
SECRA
South East Clarington Ratepayers Association
Peer Review of the LLRWMO's
Enhanced Facility Design for the
Port Granby Project
March 2006
Prepared for:
Municipality of Clarington
Prepared by:
Hardy Stevenson and Associates Limited
364 Davenport Road
Toronto, Ontario M5R 1 K6
p: 416-944-8444
t: 1-877-267-7794
f: 416-944-0900
HARDY
STEVENSON
AND ASSOCIATES
Attachment 2
To Report PSD-047-06
Table of Contents
1 Introd uction ...... ......................................................................................................... 1
1.1 Purpose of this Report.................................................................................... 2
1.2 Background.................................. ........................... .......................... ............. 3
1.3 Overview of the MPR T' s Conclusions.......................................................... 6
2 Review of the Enhanced Facility Design ................................................................. 7
2.1 History and Use of Capillary Barriers at other Facilities............................... 7
2.2 Components of the Capillary Barrier............................................................. 8
2.3 How the Capillary Barrier Functions........................................................... 11
2.4 Strengths of the Enhanced Facility Design at the Port Granby WMF......... 11
3 Enhancements to the Capillary Barrier Concept ................................................ 15
3.1 Considerations to Enhance Design .............................................................. 15
3.2 Analysis Required During Detailed Design................................................. 18
4 C on elusion II ............................................................................................................. 21
5 References ................................................................................................................ 22
Appendix A: Capillary Barriers - Status of Technology and Current Understanding
Appendix B: Operational Controls to Protect Liner During Construction
Appendix C: Response to Comments from SECRA on the Enhanced Facility Design
Peer Review of Enhanced Facility Design for the Port Granby Project
1. Introduction
Hardy Stevenson and Associates Limited (HSAL) has been retained by the Municipality
of Clarington ("the Municipality") to provide peer review assistance for the Port Granby
Long-Term Low-Level Radioactive Waste Management Project ("the Port Granby
Project"). A Municipal Peer Review Team (MPRT) under the direction ofHSAL is
engaged in providing the peer review. The core of its activities consists of reviewing
studies undertaken by the Low-Level Radioactive Waste Management Office
(LLRWMO) as part of the environmental assessment of the Port Granby Project.
MPR T' s primary concern as peer reviewers has been to ensure that the design of the
Long-Term Waste Management Facility (LTWMF) protects the natural and social
environment over the long term and that the project can be implemented without adverse
environmental effects.
The Port Granby Project consists of relocation of historic low-level radioactive waste
(LLRW) and marginally contaminated soils (MCS) from the existing waste management
site to a new engineered mound north of the existing site. The proposed new mound
utilizes a low permeability composite cover system ("cover system") to prevent moisture
from entering the waste. It also includes a low permeability composite base liner system
("liner system") below the waste to prevent any leachate from escaping from the bottom
of the mound to the environment. The liner system includes an engineered leachate
collection system from where the leachate is pumped to a treatment system.
Both the cover and liner systems as originally proposed by the LLRWMO consist of
multiple components (eight components in the cover system and three in the liner system)
made of natural soils and synthetic materials called geomembranes, each with a specific
purpose. Together with other components, the geomembranes create highly durable and
impermeable cover and liner systems for containing the waste over the life of the facility.
This minimizes any chances of water infiltration and enabling management of the
leachate during construction and in the long term.
Following a review of the above concept proposed in the draft Environmental
Assessment Study Report (EASR), the MPRT recommended a number of improvements
to the Port Granby Project and the mound design. One such improvement was the
addition of a second backup liner system to provide redundancy (i.e., the duplication of
Peer Review of Enhanced Facility Design for the Port Granby Project
critical components of a system with the intention of increasing reliability of the system)
and extra protection compared to the original single liner system.
The LLRWMO evaluated several double liner systems and concluded that none improved
the performance of the L TWMF. Instead, the LLRWMO developed an enhanced facility
design for the Port Granby Project that incorporates a capillary barrier system between
the geomembrane and the waste. This design is intended to further reduce the possibility
of water infiltration to the waste, particularly in the event of failure of the geomembrane
in the cover system. It is the LLRWMO's position that a second liner system is not
required as a result of performance improvements provided by the enhanced facility
design.
1.1 Purpose of this Report
This report briefly describes the components of the enhanced facility design and explains
how the design functions. It provides MPRT's rationale for supporting the LLRWMO's
enhanced facility design in lieu of a double liner system and our recommendations for
further optimizing the performance of this enhanced design.
The remainder of the Introduction provides the background to the development of the
enhanced facility design by the LLRWMO and an overview of the MPRT's conclusions.
The remaining sections summarize our review. Section 2 (Review of the Enhanced
Facility Design) discusses the development of capillary barriers in the waste management
industry and the strengths and weaknesses of the enhanced facility design. Section 3
(Improvements to the Capillary Barrier Concept) outlines the MPRT's recommendations
for improving the enhanced facility design and for further analysis and demonstration
during the detailed design phase of the project. Section 4 summarizes the MPRT's
conclusions regarding the enhanced facility design.
Three appendices have been included as part of this report. Appendix A discusses the
status of the capillary barrier technology, its use at other facilities in North America, and
a comparison of the Port Granby facility design to the designs used at other facilities.
Appendix B describes operational controls that will be used to protect the liner during
construction. Appendix C provides a response to comments made by representatives of
the Southeast Clarington Ratepayers Association (SECRA) on the enhanced facility
design.
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1.2 Background
After reviewing the Port Granby Environmental Assessment Study Report (EASR) in
March 2005, the MPRT concluded that the L TWMF as proposed in the EASR could be
constructed, operated, and maintained in a way that would result in minimal adverse
effects on the environment. Furthermore, the MPR T was confident that appropriate
mitigation measures could be developed to minimize any potential adverse effects
(HSAL, March 2005).
Nonetheless, the MPRT recommended improvements regarding the ability of the
L TWMF to effectively contain the wastes and the associated leachate over the lifetime of
the facility. The MPRT's key concern was that the redundancy of the liner system over
the life of the facility was insufficient and should be improved. The issues raised by the
MPRT included:
· The hydrogeological characteristics of the site and the importance of protecting
underlying soils from leachate;
· The uncertainty as to whether the geomembrane within the liner system will
deteriorate over the life of the facility;
· The tendency towards preferential use of double liners at other modern hazardous
waste management facilities in the waste management industry;
· The increased sense of comfort that a double liner system could provide to residents
by decreasing the likelihood of leakage to the underlying till and groundwater
contamination; and,
· The ease of decommissioning the site (should such action be necessary), which would
be difficult with a potential failed liner system and spread of contamination (HSAL,
March 2005: 39-40).
Based on a review of the above issues, the MPRT recommended in its Peer Review
Report of the Port Granby Project EASR that a double liner system be investigated by the
LLRWMO. In the design proposed in the EASR, the bottom liner system includes a
compacted clayey soil layer over the natural till at the site, a geomembrane, and a sand
leachate drainage layer. The underlying till soil environment provides natural attenuation
as part of the Design Concept in the event of a liner failure. The MPRT's
recommendation for a double liner system highlighted the need for redundancy in
protecting the natural till deposit at the site and the surrounding environment from
leakage in case of a failure of the geomembrane in the single liner system.
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Shortly after the MPRT recommendation, Municipal Council passed Resolution #GPA-
148-05 requesting that the LLRWMO install an additional composite base liner system at
the new L TWMF. In response, the LLRWMO prepared a Technical Memorandum in
August 2005 that compared the original single liner system to three alternative double
liner systems based on the amount of additional material to be transported, construction
duration and cost, and environmental performance (LLR WMO, August 2005). Each
alternative consisted of an additional three component system with a sand drainage layer,
high density polyethylene geomembrane, and various combinations of compacted clay
liner (CCL) or geosynthetic clay liners (GCL). Based on the results of their analysis,
LLRWMO staff concluded that the original single liner design should be retained, citing
additional costs that could be incurred (ranging from $2.8 to 4.8 million), additional
material haulage involved, an extended construction period, and insignificant
improvement in environmental performance in the various options that were studied
(LLRWMO, August 2005: 5).
After reviewing the analysis, the MPRT deemed the Technical Memorandum to be
incomplete with regard to the issues raised in the Peer Review Report. While agreeing
with the LLRMWO's conclusions regarding cost and construction effects of these
additional liner systems, the MPRT sought more analysis regarding the technical
performance of the double liner systems. In ajoint meeting of the MPRT and the
LLRWMO, it was agreed that a comprehensive review of the entire design comprising
the cover and liner systems be undertaken to assure isolation of the waste from the
environment.
As a result of this review, the LLRWMO developed an enhanced facility design for the
engineered mound that utilizes a capillary barrier and drainage system as part of the cover
system. This enhanced design reduces the possibility of moisture entering the waste and
drawing out contaminants as it exits the mound. Such a barrier is intended to further
minimize wetting of the waste in the event of leakage through the cover system,
obviating the need to enhance the redundancy of the proposed liner system with a double
liner system. Furthermore, the capillary barrier and drainage system uses instrumentation
to monitor the performance of the geomembrane.
The LLR WMO is of the opinion that the proposed enhanced system would provide
additional protection from leachate leaking into the environment by keeping the waste
drier over the long term, even in the event of a geomembrane failure in the cover system.
As a result, the LLRMWO has concluded that the double liner system would not be
needed.
Peer Review of Enhanced Facility Design for the Port Granby Project
4
To assess the appropriateness of the LLRWMO's conclusions, the MPRT reviewed
background documentation on industry experience with respect to capillary barriers,
including case studies of capillary barriers at other waste management facilities, field
demonstrations and analyses. The MPRT also reviewed the preliminary conceptual
details of the proposed cover system provided at the meeting with LLR WMO, and
attended subsequent meetings with the LLRWMO and its consultant to discuss the
proposal.
Following its assessment, the MPRT has agreed in principle with the LLRWMO's
proposal for the enhanced facility design. The MPRT indicated its support at the Public
Information Sessions held in November 2005. The MPRT has spoken with residents,
including representatives of the Southeast Clarington Ratepayers Association, to explain
why the MPRT supports the new design and to hear their concerns.
Peer Review of Enhanced Facility Design for the Port Granby Project
5
1.3 Overview of the MPRT's Conclusions
Based on the MPRT's review of the enhanced facility design proposed by the LLRWMO,
the MPRT agrees that the concept can be designed to protect the underlying till and
prevent leachate from contaminating the groundwater. Thus, the enhanced design
improves the redundancy of the overall system and provides Clarington residents with a
safe and durable long-term facility.
The MPR T' s recommendation for a double liner system was based on the uncertainty that
the single liner system would function optimally beyond several hundred years. Under
such a scenario, the upper till layer would need to provide containment of the leachate to
protect the surrounding environment should the single liner system fail over the life time
of the facility. The MPRT considered that such a scenario was not acceptable since this
would imply environmental contamination below the facility with potential for site and
groundwater contamination. The enhanced facility design meets the MPRT's
expectations with regard to environmental performance, since this concept effectively
reduces the amount of moisture contacting the waste to negligible levels in case of cover
system degradation (particularly involving failure of the geomembrane). Less reliance is
therefore placed on the liner system to manage the leachate and protect against
groundwater contamination. In addition:
· The enhanced design operates passively based on natural capillary action (i.e., no
pumps or other equipment required) in keeping the waste dry over the long term;
· It enhances the ability to monitor infiltration and remediate the cover system if
needed through the use of instrumentation that is built in to the capillary barrier;
· It uses local materials recycled from the cell excavation to construct the capillary
barrier, avoiding the need to import soil; and,
· The capillary barrier system will be less expensive than an additional liner system.
Overall, the MPRT is of the opinion that the enhanced facility design can provide for
sufficient redundancy to ensure that the water infiltration and production of leachate in
the long term will be negligible. Furthermore, the MPRT is also of the opinion that with
the enhanced facility design a double liner system is no longer necessary to meet MPRT's
expectation with respect to redundancy.
Peer Review of Enhanced Facility Design for the Port Granby Project
6
2. Review of the Enhanced Facility Design
The enhanced facility design uses a capillary barrier to effectively reduce the amount of
moisture entering the waste to negligible levels by capture, retention and drainage. While
the original cover system proposed in the EASR was designed to reduce the amount of
infiltration by means of multiple soil components, a geomembrane and a geosynthetic
clay liner, any failure of the cover system (particularly the geomembrane) to perform as
expected could potentially produce some leakage and wetting of the waste.
By preventing water from entering the waste, the capillary barrier effectively cuts off the
production of leachate once the facility is closed and the residual moisture from the
construction activities has tailed off. The base liner system would need to perform
optimally only during and shortly following the construction period, at which time the
collection and treatment of leachate is routinely carried out and the liner performance is
closely monitored. Following the construction period, production of leachate would
dramatically reduce to negligible levels, more so with a capillary barrier than in the case
of the original design.
Over the long term, the single liner system could be maintained to provide a sufficiently
redundant barrier in the unlikely event that multiple components of the cover system fail
(particularly the geomembrane, GCL and the capillary barrier system) and some leachate
production should ensue. The instrumentation would indicate such an event and
necessary remediation of the cover system would then be carried out.
2.1 History and Use of Capillary Barriers at other Facilities
Capillary barriers are used in a number of facilities in the waste management industry to
keep waste dry. Dedicated use of capillary barriers for water retention and diversion and
their licensing in different types of landfills is now increasing in the industry. In almost
all cases, such barriers consist of fine-over-coarse soil layers used as a component of
cover designs for hazardous landfills, municipal landfills, mine tailings and other
applications where minimization of water infiltration through the cover is a major
concern. Capillary barriers are considered to be low-cost, easily constructed, and long-life
options used either as alternatives to other surface cover designs or to complement soil
Peer Review of Enhanced Facility Design for the Port Granby Project
7
cover designs depending on the application (Kampf et aI, 1996; Pease et aI, 1996; Walter
et aI, 2000).
Capillary barriers are being used in a range of capacities at a number of sites in the
United States (i.e., Lee Acres Landfill Superfund site, New Mexico; Lake County
Landfill, Montana; Hanford Superfund radioactive waste site, Washington State; Gaffey
Street Sanitary Landfill, California; McPherson County Landfill, Kansas) and at
demonstration projects across the U.S. for hazardous waste, municipal solid waste, and
non-hazardous wastes. Key advantages of the capillary barriers include their ability to
retain and divert water and their constructability using natural materials and
configurations that imply longevity. Capillary barriers are also used for water balancing
in surface covers to retain water for plant growth, thereby reducing topsoil erosion of the
covers (Golder, 2005).
Recent focus on the use of capillary barriers in hazardous landfills and for remediation of
sites has brought a large amount of R&D effort into demonstrating their performance
through numerical analysis tools and field and laboratory demonstrations. The
efficiencies of capillary barriers have been studied in a number of test projects where they
have successfully demonstrated prevention of water infiltration into waste deposits
(Kampf et aI, 1996; Pease et aI, 1996; Walter et aI, 2000).
Appendix A describes the status of technology and understanding of capillary barrier
systems in the industry.
2.2 Components of the Capillary Barrier System
As shown in Figure 1, the capillary barrier proposed for the L TWMF consists of two
layers: (1) a capillary drainage layer which is a fine-grained soil layer that contains silty
sand with some clay and fine gravel to meet the capillary performance requirements; and,
(2) an underlying capillary break layer which is a coarse-grained soil layer containing
medium-to-coarse gravel. The capillary barrier is provided as a complementary barrier
(i.e., in addition to all the natural and synthetic components in the cover system) and is
located below the geomembrane and the geosynthetic clay layer (GCL) within the cover
system, and above the interim cover of the waste mound. Being situated below the
geomembrane and the GCL, the capillary barrier will generally remain dry over the life
of the facility.
Peer Review of Enhanced Facility Design for the Port Granby Project
8
The main purpose of the capillary barrier system will be to function when and if there is a
failure of the geomembrane and the GCL. It is difficult to envisage a total failure of the
geomembrane and the GCL since these are made of long lasting polyethylene and
bentonite respectively. However, local tears and punctures may occur during the
hundreds of years of performance. Even under such failure scenarios, the sand drainage
layer above the geomembrane will continue to function, thereby minimizing any
infiltration through the geomembrane. The fine-grained soil layer (capillary layer) will
then retain and drain any moisture that may escape through the geomembrane and a
perimeter drainage system will capture the lateral flow of uncontaminated moisture that is
conveyed by the capillary layer. The capillary barrier system will also include embedded
instrumentation to monitor moisture levels and the overall condition of the cover system,
providing the information necessary to detect any tears or punctures and carry out any
remedial work.
Peer Review of Enhanced Facility Design for the Port Granby Project
9
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2.3 How the Capillary Barrier Functions
The capillary barrier operates by natural capillary action to store and convey moisture
away from the waste. Under unsaturated conditions moisture is retained and travels
within the fine-grained layer more easily than into the coarse grained layer below. This is
due to the larger surface area of the fine-grained soil particles, thus creating surface
tension forces that overcome the gravitational forces. As a result, moisture is pulled
laterally throughout the upper fine-grained soil layer. Since this layer is sloped, the
moisture continues to travel laterally until it drains away to the flanks of the mound.
To sustain the capillary function, mixing of soil between the two layers should be
prevented, and a geotextile fabric is often considered to separate the two layers (not
currently provided in the LLRWMO concept). It is also important to ensure through
proper sloping that the water migrating towards the edges of the barrier does not
accumulate along the migration path and break through the capillary barrier.
For proper functioning of the capillary barrier, the barrier must remain unsaturated.
Normally such barriers are considered for arid or semi-arid areas in the waste
management industry and saturation is not a concern. Being located below the
geomembrane and the GCL, it can be expected that the capillary barrier is essentially in a
near dry state in the long term required for the proper functioning of the barrier.
2.4 Strengths of the Enhanced Facility Design at the Port
Granby WMF
As discussed previously, although the MPRT was confident that the concept as presented
in the EASR would provide long-term containment of the waste, it was not completely
satisfied that the WMF would achieve that goal based on the information and analysis
included in the report. The enhanced facility design, based on a capillary barrier and
drainage system, is expected to further enhance the performance of the Port Granby
Waste Management Facility by minimizing moisture entering the mound to negligible
levels as a first priority and the near-elimination of leachate generation in the long term
after the facility is closed. The strengths of this enhanced design are described below.
Peer Review of Enhanced Facility Design for the Port Granby Project
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2.4.1 Enhanced design reduces the amount of leachate produced in the
mound
Under normal conditions, the original cover system described in the draft EASR was
expected conservatively to permit less than 0.01% of the total precipitation from entering
the waste. According to preliminary modelling prepared by the LLRMWO, the capillary
barrier would reduce the moisture that infiltrates into the waste to barely measurable
amounts. Thus, the enhanced design of the cover system reduces reliance on the liner
system to manage the leachate and thus protect against groundwater contamination by
way of liner failure by minimizing the amount of leachate that could potentially be
created to negligible levels.
2.4.2 Enhanced design provides an effective backup for the cover system
The capillary barrier provides a more noticeable benefit under less than optimal
conditions, such as severe weather events or failure of the cover system. A fully intact
geomembrane and the geosynthetic clay liner normally would not allow any noticeable
infiltration to the waste. However, should there be minor imperfections such as tears or
punctures, some moisture could be expected to funnel its way through such
imperfections. The capillary barrier is designed to capture such infiltration before it
contacts the waste. By virtue of its holding capacity, the infiltration is retained and
diverted laterally to the edge of the mound where it naturally drains away, thus providing
an effective backup to the geosynthetic clay liner and the other layers of the cover
system.
2.4.3 Capillary barrier operates passively based on natural capillary action
and is durable
Unlike the leachate collection system, the operation of the capillary barrier does not rely
on pumps or other mechanical and electrical systems. Because the barrier uses natural
capillary action to retain or direct moisture away from the waste, it is not subject to
mechanical failure. Required longevity is expected since the capillary barrier is composed
of natural materials, which also simplifies the long-term caretaking of the capillary
barrier system.
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2.4.4 Capillary barrier is constructed using local materials recycled from
the cell excavation
As explained previously, the capillary barrier is comprised of two layers: a capillary
drainage layer that contains silty sand with some clay and fine gravel, and a capillary
break layer, which is medium to coarse gravel. The material needed to construct these
layers is available on-site through cell excavation, thus minimizing transportation impacts
and nuisance effects associated with trucking of construction materials.
2.4.5 Capillary barrier is not exposed to the elements nor to leachate
The capillary barrier is protected from the elements by about 2.3 metres of material that
comprises the original cover system. It is highly unlikely that the barrier layers would be
disturbed by the elements. Furthermore, the barrier is placed above the waste interim
cover, thereby preventing any contact with leachate, which is created in the mound
during the construction period. As the waste dries up following construction phase, the
capillary barrier can be expected to be unsaturated and become fully dry with time. Thus,
the barrier system is expected to remain fully functional over the lifetime of the facility.
2.4.6 Capillary barrier has an active monitoring system
An important element of the capillary barrier is the active monitoring system. The
LLR WMO proposes to use two types of instrumentation: (1) thermoconductivity sensors,
which measure negative porewater pressure, or the ability for water to be retained within
the capillary drainage layer; and (2) neutron probes, which measure the water content in
the soil. These instruments will be able to verify that the cover system is functioning as
intended. With proper design, the instrumentation can help locate the failure of the liner
and aid in cover remediation. These instruments can also detect a failure of the capillary
barrier (such as due to saturation) before it occurs and indicate whether the waste could
become wet. This will allow for timely remediation of the cover system, adding a level of
sophistication not found in the original design.
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2.4.7 Capillary barrier can be repaired if necessary
Should the active monitoring system identify the unlikely scenario of a breach in the
barrier, the capillary barrier can be repaired more easily than the liner system. Given its
location above the waste, repairing the barrier requires only removal of the layers of the
cover system without the need to excavate the waste.
Peer Review of Enhanced Facility Design for the Port Granby Project
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3. Enhancements to the Capillary Barrier Concept
Based on the information provided to us by the LLRWMO and supplementary research,
the MPR T agrees that the enhanced facility design is a significant improvement to the
original WMF design. It meets the key objectives that the MPRT sought from the
original design, namely:
· Protecting the underlying till;
· Preventing leachate from contaminating the groundwater;
· Providing redundancy in the design of the facility; and,
· Providing Clarington residents and Council with a state-of-the-art facility and an
increased level of confidence.
The MPRT understands from the LLRWMO that the EASR is being revised to
incorporate this concept, and that preliminary modelling and analysis has been
undertaken to determine whether the enhancements to the design have any influence on
the predicted environmental effects. Should these assessments confirm that the enhanced
facility design will not have any adverse effects, the MPRT will support the adoption of
the enhanced facility design into the project.
Furthermore, the MPRT expects to see construction / development and safety
performance details provided in the Design and Construction Plan that is submitted as
part of the Canadian Nuclear Safety Commission (CNSC) licensing requirements. Such
details should demonstrate that all necessary parameters discussed in this section have
been assessed and that the capillary barrier will function as intended in the operational
stage.
3.1 Considerations to Enhance Design
The MPRT recognizes that the information provided to date, while indicative of the
conceptual details of the enhanced facility design, requires further elaboration in terms of
environmental effects and engineering details. The following considerations are intended
to support such a process and assure the performance of the capillary barrier system as
expected at the current conceptual stage (see Figure 2 for an illustration).
Peer Review of Enhanced Facility Design for the Port Granby Project
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The MPRT expects that the LLRMWO will take into account these considerations in the
preparation of the revised EASR, detailed design and performance modeling to fully
demonstrate the effectiveness of the capillary barrier system.
3.1.1 Investigate whether a transport layer would improve the ability of the
capillary barrier to divert moisture
The capillary barrier proposed by the LLRWMO uses two layers: a capillary drainage
layer and a capillary break layer. Studies have shown that the addition of a transport
layer between the two layers significantly improves capillary performance by reducing
the amount of moisture in the upper layer. Transport layers are also capable of increasing
the (horizontal) distance that moisture is diverted (Pease et aI, 1996). Typically, the
transport layer is constructed of fine sand and located immediately above the fine/coarse
interface. Introduction of such a transport layer should be investigated.
3.1.2 Extend the geomembrane liner to "wrap around" the capillary break
layer
In the conceptual design, the capillary layer extends beyond the edge of the two
geomembrane liners, installed in the cover and liner systems, in order to drain moisture
into the perimeter ditch. In the event of heavy flooding, it is possible that moisture could
back up and travel against gravity along the capillary drainage layer, break through the
capillary break layer, and enter the mound. To prevent this situation from occurring, the
MPRT suggests extending the geomembrane liner in the liner system so that it covers a
portion of the capillary break layer (see Figure 2). Alternately, the drainage could be
achieved with an enclosed system not accessible to the outside soil environment (i.e.,
ensuring that the capillary barrier and drainage system does not extend beyond the
geomembranes and that drainage is provided by collection pipes along the perimeter, in
which case the geomembranes could be joined to provide full containment of the waste).
3.1.3 Ensure durability and redundancy of monitoring instrumentation
One of the benefits of the enhanced facility design is the ability to monitor the
performance of the capillary layer. While the instrumentation should be designed to be
durable, malfunctions and breakdowns are possible given the extended lifetime of the
Peer Review of Enhanced Facility Design for the Port Granby Project
17
project. To reduce the chances of failure, we recommend that careful attention be given
to ensure that adequate redundancy is provided in instrumentation. Such instrumentation
should also improve the ability to pinpoint the location of any leakage such that repairs
can be made easier.
3.2 Analysis Required During Detailed Design
As described in Section 2.1 and Appendix A, capillary barriers are used in a number of
facilities in the waste management industry for containing hazardous, municipal solid
waste, and non-hazardous wastes. At these facilities, the capillary barriers provide the
primary and often sole means of keeping the waste dry. The capillary barrier concept as
envisaged by the LLRWMO, namely to provide redundancy for a low-permeability cover
system, does not seem to be explicitly applied elsewhere in the waste management
industry in a similar context as described here. The concept must therefore be
customized to the particular application in Port Granby, including requirements of the
waste, soils and the geological conditions of the site. Being at a conceptual level, the
performance of the barrier must be fully demonstrated through detailed hydraulic
modeling and laboratory testing. Areas requiring analysis are described below.
3.2.1 Determine maximum flow before breakthrough occurs
Under normal conditions, the geomembrane in the cover system is considered essentially
impervious with less than 0.1 mm of moisture expected to reach the capillary barrier per
year. Should the geomembrane fail and significant infiltration occurs, the capillary
barrier may need to drain larger amounts of moisture away from the mound. The MPR T
would like to see the results of detailed performance modeling to determine the
maximum flow that the capillary barrier can handle before becoming saturated and
failing, thus necessitating remedial response. As described above, the addition of a
transport layer should increase the amount of flow that the barrier can handle before its
performance is compromised.
3.2.2 Assess the effect of funneling flow patterns on the capillary barrier
When used at municipal landfills, the capillary barrier is positioned at the top of the
surface cover and is exposed to surficial infiltration over the full extent of the barrier
Peer Review of Enhanced Facility Design for the Port Granby Project
18
surface. In other words, the amount of moisture that the capillary barrier is exposed to is
uniform throughout the landfill. Conversely, in the enhanced facility design for the Port
Granby WMF, the capillary barriers will likely be exposed to very localized infiltration
due to tears or punctures in the geomembrane and the GCL. Such infiltration could
introduce localized funneling flows, the effects of which could be different on the
capillary layer in terms of maximum flows before breakthrough occurs (Walter et aI,
2000). The effect of such funneling should be investigated.
3.2.3 Optimize the slope and length of the capillary barrier layers
Because the capillary barrier acts by natural capillary action, and hence is influenced by
gravity, the slope of the soil layers is essential to the effective functioning of the barrier.
The proposed slope (of 5%) needs to be analyzed. A steeper slope may be required to
properly drain the water without breakthrough of the water to the capillary block. It is
also necessary to ensure that the slope length is appropriate so that the accumulation of
moisture along the diversion path does not lead to capillary breakthrough.
3.2.4 Optimize the soil depths and hydraulic properties of the layers of the
capillary barrier system
The soil depths and hydraulic properties of the layers are also crucial to effective
functioning of the barrier. In the conceptual drawings for the enhanced facility design, all
the layers are shown to be of uniform depth throughout the mound. The results of
hydraulic modeling may indicate that the depth of the capillary barrier layers should be
greater at the edge of the mound to handle the larger volumes of moisture.
3.2.5 Assess the possibility of mixing of soils within the capillary barrier
layers
The chances of fine soil gravitating towards coarse soil during placement or over time
should be minimized since this could impair the effectiveness of the barrier. Laboratory
testing should be used to determine whether the soils proposed for the two layers of the
capillary barrier are appropriate for construction purposes.
Peer Review of Enhanced Facility Design for the Port Granby Project
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3.2.6 Determine how to construct the facility effectively and efficiently
The cover system, including the capillary barrier system, consists of 10 layers of material,
both natural and synthetic. To function optimally, the cover system needs to be installed
based on tested methods, as does the liner system. With respect to the capillary barrier,
there may be a need for field trial testing to assure constructability and appropriate
material processing (i.e. screening of soil and mixture preparation).
3.2.7 Assess institutional requirements towards the caretaking and
maintenance and remedial actions
The capillary and drainage system will require some degree of caretaking and
maintenance over the life of the facility particularly with respect to instrumentation. As
indicated in the MPRT's comments on the Port Granby EASR, plans must be prepared to
describe how the necessary resources for caretaking and maintenance will be in place
long after construction is completed. These plans must apply to all aspects of the Port
Granby facility, including the capillary barrier system. The MPRT expects that these
plans will be prepared during the detailed design phase of this project, and furthermore,
that such plans will identify the specific institutional requirements of the capillary barrier
and its instrumentation, in addition to all other elements of the engineered facility.
Peer Review of Enhanced Facility Design for the Port Granby Project
20
114. Conclusion
I
The MPRT is pleased that the LLRWMO has considered our concerns regarding the
redundancy of the original Port Granby L TWMF design and has developed an enhanced
facility design. The MPRT concurs with the LLRWMO that the enhanced facility design
addresses the concerns of the MPRT expressed in the Peer Review Report of the EASR,
making a double liner system technically unnecessary. As indicated previously, we are
confident that this concept can be designed and constructed to:
· Protect the underlying till;
· Prevent leachate from contaminating the groundwater;
· Provide redundancy in the design of the facility; and,
· Provide Clarington residents and Council with a state-of-the-art facility and an
increased level of confidence.
Because this design is at the conceptual level, we expect to see additional analysis and
modeling done to optimize the design and demonstrate that it functions as expected. The
MPRT would also like to see the LLRWMO investigate several changes to the design of
the capillary barrier system that it determines will enhance the performance. These were
discussed in Section 3.
During our review of the revised EASR, the MPR T will be cognizant of any changes to
the findings of the EASR associated with the introduction of the capillary barrier and
drainage system in the construction and operation of the L TWMF. The MPR T will work
closely with the LLRWMO to resolve any new issues that may arise as a result of the
enhanced facility design.
Peer Review of Enhanced Facility Design for the Port Granby Project
21
5. References
Atomic Energy of Canada Limited. 2005. Investigation of Clarington Requested
Modifications to the Port Granby Project, Technical Memorandum from Rick Rossi to
Glenn Case, August 19,2005.
Golder Associates. 2005. Publications on Capillary Barriers for Minimizing Infiltration.
Golder Associates. 2005. Schematic of Capillary Barrier System for Mound Cover
Design.
Hardy Stevenson and Associates Limited. 2005. Peer Review of the Port Granby
Environmental Assessment Study Report.
Kampf, Markus, Tilman Holfelder and Hector Montenegro. 1998. "Inspection and
Numerical Simulations of Flow Processes in Capillary Barrier Cover Systems", Institute
of Hydraulic and Water Resources Engineering, Darmstadt University of Technology.
Pease, R.E. and J.C. 1996. "Stormont: Increasing the Diversion Length of Capillary
Barriers", University of New Mexico. Proceedings of the HSRC/WERC Joint Conf. On
the Environment.
Walter, M.T., et al. 2000. "Funneled Flow Mechanisms in a Sloping Layered Soil:
Laboratory Investigation" , Water Resources Research.
Peer Review of Enhanced Facility Design for the Port Granby Project
22
Appendix A: Capillary Barriers - Status of Technology
and Current Understanding
Capillary barrier and drainage systems minimize infiltration when used as part of the
overall soil cover system in landfills. Their contribution to the efficacy of landfill covers
is well recognized. Significant research and development (R&D), including numerical
models and field data, has been carried out in recent years in the U.S.' Capillary barrier
systems have been used to remediate old landfills, mine tailings and waste impoundments
to meet the modem landfill requirements, such as in the U.S. Superfund remediation
programs. Old systems generally consisted of poorly designed soil covers and bottom
liners (if at all) using clays and other soils. They did not have the benefit of modem
synthetic geomembranes and various design improvements such as engineered composite
cover systems and base liner systems. Capillary barrier and drainage systems have
provided a viable alternative to prevent the entry of moisture into the waste and
effectively eliminate the production of leachate.
The effect of capillary forces in landfill drainage has been known for several decades.
Although the development of engineered barriers based on principles of capillary barrier
and drainage is of recent origin, there are clear examples of such designed barriers. A
survey of recent literature indicates that the application of capillary barriers is being
increasingly considered in the waste management industry in general extending to mine
waste and radioactive waste sites.
Table 1 summarizes facilities and major R&D projects and field trials for the
development and evaluation of capillary barriers. Reference 1 provides a number of key
research papers that demonstrate the ability of capillary barriers to minimize infiltration.
In the case of landfills, capillary barriers are used mostly as alternatives to thick soil
layers to reduce drainage and to retain water such that evapo-transpiration (ET) by means
of plant growth on the covers can be augmented. Experience indicates that capillary
barriers carry out this function successfully. Capillary barrier based cover systems also
meet regulatory and other requirements with respect to infiltration of water to the waste,
ease of construction, cost and longevity.
I Golder Associates: Publications on Capillary Barriers for Minimizing Infiltration, 2005.
Peer Review of Enhanced Facility Design for the Port Granby Project
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It should be noted that in the context of the enhanced facility design, the function of the
capillary barrier has been improved. The capillary barrier is located below the thick soil
layers, the synthetic geomembrane, and the geosynthetic clay layer (OCL) and above the
interim soil cover on the waste. The capillary barrier is thus prevented from being
exposed to levels of drainage typical of the soil covers (which are laterally drained
through the sand drainage layer above the geomembrane) and is normally in a near dry
state. It is exposed to moisture only in the event of failure of the geomembrane and the
OCL used in the cover system. Most likely, such failures would be due to localized
defects (such as tears and punctures) and the drainage of water reaching the
geomembrane through the sand drainage layer would still be mostly effective.
If a defect occurs in the geomembrane, some moisture will pass through the sand
drainage layer. The capillary barrier is designed to capture, retain and drain any such
moisture. Therefore, the functional requirements in the enhanced facility design are less
onerous than in cases discussed earlier where the capillary barrier is used as an alternative
for thick soil covers to improve drainage and evapo-transpiration.
Because of this difference, direct comparative cases to evaluate the enhanced facility
design are few, although the MPRT is confident that the enhanced design will perform
equally well, if not better, than barriers at locations referenced in Table 1. Nonetheless,
it is considered necessary to carry out specific studies to refine the design and
constructability and assure performance, as discussed in the Peer Review Report.
A number of major projects that use engineered mounds have been reviewed by the
LLRWMO during the Feasibility Studies2. To our knowledge, none of these precedent
projects (viz. Weldon Springs Site, Missouri; Edgemont Mill Site, South Dakota;
Canonsburg Mill site, Pennsylvania; Niagara Falls Storage Site, New York State; and two
Canadian sites namely Passmore Interim Storage Site, Ontario and the Long-term
Management facility in Fort McMurray Alberta) appear to have used the capillary
barriers in their cover design. Two of these sites, viz., Weldon Spring and Passmore site
facilities have double liners. The Canonsburg Site has used however a capillary barrier
system as the base liner (a two foot clay liner overlaying a one foot sand capillary break
layer) to prevent leachate infiltration to the environment.
Table 2 provides a comparative summary of information as it relates to the cover and
liner systems and capillary barrier systems where available in the facilities discussed
earlier.
2 Port Granby Project Environmental Assessment Qualified Concept Report (Report LLRWMO-03710-
ENA-13003)
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Appendix B: Operational Controls to Protect Liner
During Construction
The base liner system in the Port Granby project consists of a composite liner system
with a leachate collection sand layer over a HDPE geomembrane which in turn is laid
over a compacted clay layer. The base liner system is constructed over the natural till site.
The liner system also includes a leachate collection system consisting of a leachate sump,
perforated collection pipes, and riser pipes, which are all located in the sand drainage
layer.
During placement of the base liner system, there are a number of operational controls
used to protect the high-density polyethylene (HOPE) geomembrane layer. First, the
compacted clayey soil liner (CCL) is prepared to ensure that it is smooth and provides a
proper base for the HOPE. To accomplish this, it is "sealed" at the end of each
construction day using a smooth drum roller. A similar process is used upon completion
of construction of the CCL to provide a smooth surface upon which the geomembrane
liner will be placed. Prior to installation of the HOPE, it is carefully inspected to ensure
that there are no foreign objects (i.e., rocks) that could puncture the geomembrane.
The HOPE is installed using track-mounted equipment. A cushion of 300 mm of sand
(which will also be used for housing leachate collection system) is placed over the liner
to support the equipment, thus ensuring that no machinery is in direct contact with the
liner. The rolls of HDPE are placed in parallel, as the material is strongest longitudinally.
The seams of the HOPE are then welded together to create a watertight barrier. The
welding process is subject to stringent inspection and quality control. Once the entire
geomembrane has been installed, it is tested for leaks before the soil material is placed
overtop.
Full-time field quality assurance inspection and testing occurs throughout the
construction period to identify and potentially reduce construction deficiencies.
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Appendix C: Response to Comments from SECRA on
the Enhanced Facility Design
At the January 30 Clarington Council Meeting, two members of the South East
Clarington Ratepayers Association (SECRA) made submissions outlining their concerns
regarding the Enhanced Facility Concept. The MPRT reviewed these concerns and the
responses are given below, itemized against the specific comments with regard to the
Enhanced facility Design raised in the submissions (comments are abbreviated here; for
detailed discussion of the comments, the submissions should be referred to). While some
of the concerns relate to detailed design and are being taken into consideration in the
ongoing work at the LLRWMO, the MPRT believes that none of these concerns reflect a
need to change the recommendations in the Peer Review Report.
Comments/Questions by Dr. Sarwan Sahota, SECRA
1. The idea of storing low-level radioactive waste in an engineered mound
is experimental in nature. This method of storing the radioactive waste is a hypothesis
and it needs a careful scientific study before concluding that such waste can be stored
in this manner for a long-term (page 1, para 2 of the Submission).
Res/Jonse: A number of sites in the US, Canada and Europe have used engineered
mounds for storage of LLR Wand contaminated soils. The Port Granby Project
Environmental Assessment Qualified Concept Report summarizes several
representative examples. The LLR WMO has studied the engineered mound concept
for the Port Granby Project in substantial scientific detail to the level required by the
Environmental Assessment process.
The MP RT reviewed this information in detail and provided extensive comments.
LLR WMO has made revisions to their reports and conclusions based on the MP RT
comments. The MPRT is now satisfied that the concept is scientifically sound and
that the waste can be stored safely for the long term. Further studies and detailed
design of the concept will be carried out by the LLRWMO to advance this concept
into the development and construction phase.
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2. In December 2005, LLR WMO informed the people of southeast Clarington that it is
not necessary to have a bottom liner for the proposed mound and its original proposal
is to be modified to include an improvement to the top liner only. Furthermore, we
were shocked to learn that the Municipality has agreed to this modified proposal and
the Municipal consultants and staff were in negotiations with a team from LLRWMO
during the summer. They appear to have developed a cozy relationship with each
other and it is detrimental to the interests of the Municipality and its people. The
people of southeast Clarington were not consulted by anyone in this regard (page 1,
para 3).
We do not agree. Public meetings were held by the LLRWMO to discuss and obtain
feedback on the Enhanced Facility Design with the Clarington public (including
Southeast Clarington). The process that led to the review of the original design, the
review of the double liner option, and the modified Enhancedfacility Design was
transparent and clearly described in the Peer Review Report (1.2 Background). It is
the MPRT's belief that the enhanced facility design is in the best interest of the
Municipality and its people. Otherwise, the MPRTwould not have supported the
concept.
3. To the best of our knowledge, the Municipal Peer Review Team has no prior
experience in advising on or building an ENGINEERED MOUND for the long-term
storage of radioactive waste (page 2, para 1).
The MP RT has significant experience related to radioactive waste and projects of this
nature, including projects that are much more complex in terms of scientific
demonstration and assessments.
4. We have been told by the MPRT that the proposed Mound Design is probably O.K.
Do they really know if the proposed mound design is safe? (page 2, para 1).
The MPRT has reviewed in the past year the Qualified Concept, project description
documents, and environmental assessment documentation, all based on the original
design. As part of this documentation, we have reviewed human health and safety
considerations relating to all aspects of the Port Granby Project. The MPRT stated in
its Peer Review Report of the Environmental Assessment Study Report that the
concept would provide long-term containment of the LLRW The Enhanced Facility
Peer Review of Enhanced Facility Design for the Port Granby Project
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Design is an improvement over the original design in that the infiltration of water to
the waste will be minimized. This will effectively eliminate the production of
leachate. The MPRT is satisfied that the enhanced design is safe.
5. Are there compromises being made in order to get on with the project? (page 2, para
1 ).
No. The Enhanced Facility Design represents an improvement, not a compromise.
The rationale for recommending the Enhanced Facility Design is explained in detail
in the Peer Review Document (Sections 1.3 and 2). The MPRT is of the view that the
Enhanced Facility Design meets all the objectives that the original design could not
meet and does so with less cost, and with better degree of waste protection from
infiltration compared to the options involving the use of the double liner. No
compromises have been made in order to get on with the project.
6. It is our considered opinion that, at a minimum, a bottom double liner is very
necessary for a mound of questionable design to store radioactive waste for long-
term. It is possible to make the case for a triple liner in order to build an extra layer of
safety into an experimental design (page 2, para 2).
With the Enhanced Facility Design, any infiltration, even under the eventuality of the
failure of the synthetic geomembrane in the cover system, will be captured, retained
and drained by the capillary barrier system. Aside from the initial construction
period, there will be effectively no generation of leachate from the facility. A bottom
liner system with a single liner will manage any minor volume of leachate that might
be produced during the life of the facility. The various layers of soil cover, the
geomembrane and the capillary barrier drainage system will reduce the likelihood of
wetting of the waste following the construction phase and over the life of the facility
to negligible levels.
Therefore the technical case for a double liner, let alone a triple liner, cannot be
supported. The approach of preventing leachate production by eliminating infiltration
is superior to provide additional liner systems, since it also minimizes the volume of
leachate that may require collection and treatment. We do not agree with the
characterization that the mound is of 'questionable design' and is 'experimental '. The
design is based on experience elsewhere and has been assessed to ensure that the
radioactive waste can be stored safely for the long term.
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7. It is our understanding that in the United States a double liner is commonly used to
store municipal and radioactive waste (page 2, para 2).
Double liners have been recently used for hazardous wastes in the us. With the
Enhanced Facility Design, a double liner will provide no more safety than a single
liner design because of the negligible likelihood of leachate generation following
construction over the life of the facility, as discussed in points 4 and 6 above. The
MP RT is satisfied that the enhanced design provides redundancy and long-term
containment of the LLR W such that a double liner system cannot be justified on
technical grounds.
8. In our opinion redesign of the top liner to include a sand drainage layer in the top
liner (cover system?) provides a marginal improvement to the proposed mound (page
2, para 2).
We do not agree with the characterization of the capillary barrier and drainage
system as a sand drainage layer. The functioning principle and description of the
capillary barrier is given in the Peer Review Report. Normally, the infiltration though
the cover system is prevented by the synthetic geomembrane made of High Density
Polyethylene (HDP E), which is expected to last several hundred years. In the
eventuality of the failure of the HDP E, the capillary barrier system will retain and
drain any moisture that will pass through the geomembrane. The MPRT is of the
opinion that the capillary barrier will prevent entry of moisture into the waste and
eliminate resulting leachate generation.
9. The liner can be easily punctured or fused joints may fail thereby causing serious
problem and such a problem may be impossible to fix (page 2, para 3).
The development and installation of the modern geomembranes involve technologies
that have evolved over decades and the state of the art is such that the current genre
of these geomembranes can be installed and quality assured to last for a long time
(hundreds of years). Although the type offailures discussed in the comment above
could occur, the MPRT considers such events to be very unlikely. There are
numerous operational controls in place to ensure that the liner maintains its
structural integrity, as explained in Appendix B.
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10. The primary reason for LLR WMO's reluctance to agree to a double liner is purely
financial (page 2, para 5).
It is our understanding that the LLRWMO 's reluctance to agree to a double liner
primarily stems from the LLR WMO 's argument that a single liner is adequate in
meeting all safety and environmental protection requirements. Cost was a subsidiary
factor, if at all.
11. We are dealing with the long-term health and safety of our population and we should
not allow any short cuts (page 2, para 5).
The MPRT agrees. No short cuts are being made in the Port Granby Project in
dealing with long-term health and safety.
12. The proposed preferred design option makes no mention of a contingency plan in the
event proposed design fails (page 2, para 6).
The capillary barrier system will have necessary instrumentation to detect the failure
of the geomembrane in the cover system and its location. This will enable timely
repair of the cover system. Again, repair of the cover system is possible, whereas
repair of the liner cannot be conducted after the site is completed.
13. Will the municipality have the power to intervene if changes are made to the
proposed design that may seriously compromise the integrity of the project once the
proposed preferred option is approved by the Council? (page 3, para 1).
The Agreement between the two municipalities and the federal government discusses
the consultation process between the parties during the EA and construction phases
o.fthe project. The Municipality could intervene at any time (fthere are reasons to do
so.
14. LLR WMO should be required to submit a final engineering design to the
Municipality for approval before proceeding with the construction phase of the
project (page 3, para 2).
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The Municipality expects to be fully involved in the detailed engineering and
construction phase of the project and will have access to project information through
joint committees currently under formulation. The Agreement between the
Municipality and the Federal Government describes the consultation process during
the EA and construction phases of the project and provides for cooperation and
action between the Parties that is "necessary to expedite the completion of the
Elements of the Project in accordance with the intent of this Agreement".
15. We request that the Municipality ask the responsible Authorities to establish an
Assessment Review Panel to assess the viability of the proposed conceptual design
for the Port Granby project.
The proposed conceptual design and various environmental assessment
documentation are being reviewed by a number offederal agencies such as the
CNSC, NRCan, Department of Fisheries, Health Canada and Transport Canada. If
the federal agencies are satisfied that the Environmental Assessment Study Report
fulfils the requirements of the Scope of the Environmental Assessment, it will be
unnecessary for the Municipality to request the Responsible Authorities to establish
an Assessment Review Panel. If the reviews identify the need for an Assessment
Panel, the Responsible Authorities would be moving towards one as a matter of
process.
Comments/Questions from Mr. John Stephenson, SECRA
16. The base liner only contains two water impermeable layers and therefore is only 0.77
metres thick. The sand layer, said to be part of the base liner, is designed to allow
leachate to drain to the bottom of the pit (Comment 1.1, page 1).
The base liner has three layers, 0.75 m compacted clay liner, a HDPE geomembrane
(2 mm) and a sand drainage layer (0.5 m) that includes leachate collection and
drainage lines. All three layers are integral part of the base liner system.
17. The Low-level Office has considered 3 new alternative designs to improve the
performance of the base liner; but did not consider an option which will materially
improve the reliability of the base liner. Two new layers to the original design have
Peer Review of Enhanced Facility Design for the Port Granby Project
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been suggested: a geo-synthetic clay liner (GCL) below the HDPE liner and a second
HDPE liner below GCL; major advantage of such a system is overall increase in
mechanical strength of base liner, rather than decrease in amount of water which may
permeate through membrane (Comment 1.2, page I).
The MP RT is of the opinion that a capillary barrier system is better than a second
liner. With the capillary barrier, there is less dependence on the bottom liner since it
effectively prevents moisture from entering the waste, even in the event of the failure
of the geomembrane in the cover system. We are of the opinion that the original
bottom liner design has sufficient mechanical strength to prevent failure.
18. Soils used to construct the capillary layer will not function as expected (i.e., water
will flow into the gravel layer and enter the mound rather than to the drainage ditch);
soils for capillary layer need to be carefully selected for particle size, crystal
characteristics, and uniformity. It will not do to select any old sand/soil for this
purpose (Comment 2.1, page 2).
The MPRT agrees that capillary drainage is contingent on proper design of the
barrier system. With respect to the soils used, it is agreed that proper grading and
mixing of soils is needed. In this regard, we have made several recommendations with
respect to improvements of the enhanced design in our Peer Review Report. The
LLR WMO is cognizant of these requirements and have informed us that they are
addressing our recommendations both for providing input to the EASR and for the
detailed design of the system.
19. Effect of water vapour arising from waste will lead to water saturation in the capillary
layer (Comment 2.1 (iii), page 3).
Soon after the construction phase is over, the water content in the waste will deplete
to levels where leachate production will stop. Under these near dry conditions, the
capillary barrier will function essentially as a dry barrier. In the event that the
geomembrane in the cover system develops defects and allows moisture to enter the
capillary barrier, it will then be captured and drained by the barrier system. The
potential for saturation of the capillary barrier will be considered in the detailed
design to ensure that it has sufficient capacity to convey the moisture away from the
waste, even if the geomembrane should fail.
Peer Review of Enhanced Facility Design for the Port Granby Project
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20. Capillary layer should have an impermeable membrane installed underneath it
(Comment 2.1 (iii), page 3).
The MPRT does not think that another impermeable membrane is needed below the
capillary barrier. There is a cover soil layer below the capillary break layer that will
provide the required water retention capability before there is any chance of the
waste being wetted due to multiple failures involving the geomembrane and the
capillary barrier and drainage system.
21. Instrumentation to be inserted into capillary layer will not be serviceable for more
than 10 years (Comment 2.1 (iv), page 3).
Care will be exercised in selecting and designing the instrumentation system.
Components of the system will be chosenfor required durability, ease of replacement
even if it fails, and redundancy to ensure that the instrumentation provides necessary
information even under conditions where some instrumentation malfunctions.
22. Remediation of cover system or base liner following failure will be very expensive;
damage from heavy equipment and settling of the waste are cited as examples for
failure (Comment 2.1 (iv), page 3).
Being an improvement over the original design, the Enhanced Facility Design makes
it less likely that the waste will ever be wetted. As a result, the need for replacement
of the bottom liner should be less likely as there will be no leachate generation to
contend with even if the cover develops defects over time. Remediation of the cover
system can be achieved much more easily than in the original design since the
instrumentation will provide information that would help in finding the location of the
cover failure.
Furthermore, proper construction procedures and quality assurance methods will
ensure that the geomembranes are not damaged during construction. Various waste
stabilization and mound construction practices would minimize any effects from
settling.
Peer Review of Enhanced Facility Design for the Port Granby Project
A18
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Attachment 3
To Report PSD-047-06
EACL
low-level Radioactive
Waste Management
Office
5 Mill Street South
Port Hope, Ontario
Canada LlA 2S6
(905) 885-9488
Fax (905) 885-0273
Mayor John Mutton & Council
Municipality of Clarington
40 Temperance St.
Bowmanville, ON
LIC 3A6
Bureau de gestion des
dlichets radioactifs
de faible activite
5, rue Mill sud
Port Hope (Ontario}
Canada LlA 2S6
(905) 885-9488
Fax (905) 885-0273
LLRVVMC>-121255-02l-l3000
GGC-06-07l
2006 March 31
Dear Mayor & Council:
Draft Port Granbv EASR
The Low-Level Radioactive VVaste Management Office is pleased to present the revised
Port Granby Project Environmental Assessment Study Report (as Rev. Od5) to the
Municipality of Clarington for review by your staff and peer review team. Printed copies
of the 854 page report are being made available to your staff, to the South-East
Clarington Ratepayers Association and at the main Clarington public library and the
Project Information Exchange. The Draft Report on CD is being circulated for comment
to many residents, interest groups and other stakeholders. We would like to receive
comments by May 3,2006 in order to properly consider this input and respond to the
comments, before submitting the Final Draft to Clarington Council for consideration in
early June.
This Draft Report reflects improvements to the Project that have resulted from
discussions with your staff and peer review team and local residents regarding the
protection of the environment and the safety of current and future local residents. In
March 2005, the Municipality of Clarington requested that we investigate three issues:
. Adding another base liner system to the above-ground mound design;
. Installing a grade separation for the waste haulage route at Lakeshore Road; and
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to the start of the Project.
The LLRVVMO understands your objective in requesting a second liner system in the
Long Term VVaste Management Facility was to increase confidence in the long-term
environmental safety of the new facility. The question raised by residents and your peer
review team was how do you ensure safety if the geo-membrane in the base of the mound
malfunctions or deteriorates? Our primary objective has always been environmental and
human safety over both the short and the long term and we would not have presented the
original design to you if we had any doubts about its long-term safety. But, you gave us a
task and we investigated the issue.
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What we found was that inclusion of a second base liner system did not enhance the
protective features of the mound to any significant extent, but that it could have a
noticeable effect on local residents through increased trucking of materials and a longer
construction period. Your peer review team challenged us to do better, so we
investigated a method of securing the contamination in the mound even in the event that
the geomembrance component of the base liner system were to fail. We recommended
the addition of a Capillary Drainage Layer system in the top cover of the facility to
greatly increase its ability to keep the wastes dry for the long term. This was found to be
a much better design enhancement than incorporating a double liner in the base of the
facility. In fact, the peer review team has said, "We presented you with a potential
problem and asked for a cure. Instead the LLRWMO came back with a prevention."
I'd briefly like to point out three other improvements that we have made in the Project at
the request of the Municipality and the residents, all of which are intended to reduce the
socio-economic effects of the Project on local residents. First, we have offered to install
an underpass below Lakeshore Road so that trucks hauling low-level radioactive waste
will not come in contact with publicly accessible roads. Second, we have identified the
necessary up-grades to the municipal roadways being used to carry construction materials
to the site before the Project begins. In addition, residents have asked us for baseline
radiation surveys of private properties in the neighbourhood of the existing and new
facilities. We have agreed to provide the local residents with this service and to keep
them continuously up-to-date on environmental monitoring results. We hope that in this
way we'll build their confidence and trust in the long-term safety of the Project.
The EASR has bound into it the Comment and Disposition form used by the PRT in 2005
to record their comments on the 2005 January Version of the report (Rev. Od3). This
form has been recently updated by the LLRWMO to provide additional respo~se to the
comments where the PRT had not accepted the original response. As a result of the
federal review of the Port Hope EASR, the LLRWMO has anticipated similar issues with
respect to the Port Oranby EASR and has therefore significantly augmented this version
of the EASR in relevant sections. We believe that as a result of the revisions to the report
due to the changes in design, and due to addressing the federal review issues regarding
the Port Hope EASR, that the PRT should now find the revised responses acceptable.
TIle LLR~,VM:O sup pons the posirioil Council, 'chat Ihe Port Gr::mby project :chadd
have as little an effect on local people as possible while protecting the health and safety
of current and future generations. We believe that that changes made to the EASR over
the past year enhance the project and greatly increase confidence that we will reach our
joint objectives. ~
O. nn Case, P. Eng.
Manager, Projects & Facilities Development
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