401 KAR 48:080.
Liner and cap design requirements for contained landfills.
RELATES TO: KRS
224.01, 224.10, 224.40, 224.43, 224.99
STATUTORY AUTHORITY:
KRS 224.10-100, 224.40-305
NECESSITY, FUNCTION,
AND CONFORMITY: KRS Chapter 224 requires the cabinet to adopt rules and
administrative regulations for the managing, processing, or disposal of solid
wastes. KRS 224.40-305 requires that persons engaging in the managing,
processing, or disposal of waste obtain a permit. This chapter establishes the
minimum technical standards for solid waste sites or facilities. This
administrative regulation sets forth the liner and cap design requirements for
contained landfills.
Section 1. Liners
for Contained Landfills. At a minimum all contained landfills shall have:
(1) A primary
composite liner as specified in Sections 2 and 7 of this administrative
regulation; and
(2) A secondary
composite liner that:
(a) Meets the
secondary liner criteria specified in Sections 2 and 7 of this administrative
regulation; or
(b) Is a naturally
occurring material provided that such natural material:
1. Shall be
equivalent to material with a minimum thickness of twenty (20) feet with a
maximum permeability of 1 x 10-7 centimeters per second;
2. Shall lie above
the uppermost aquifer; and
3. Shall
continuously underlie the landfill site or facility and be demonstrated to have
sufficient integrity to protect the uppermost aquifer from contamination in the
event of a breech of the primary composite liner.
Section 2.
Components of Contained Landfill Liner Systems. Once the subgrade is
established, the primary and secondary liner systems shall consist of the
layers, listed in subsections (1) through (3) of this section.
(1) The secondary
liner system shall consist of the following layers, listed from bottom to top:
(a) A twelve (12)
inch soil layer with a permeability of 1 x 10-7 centimeters per
second as specified in Section 4 of this administrative regulation;
(b) A secondary
synthetic liner as specified in Section 5 of this administrative regulation;
(c) A twelve (12)
inch drainage layer with a permeability of 1 x 10-3 centimeters per
second; and
(d) A filter fabric
or other material approved by the cabinet.
(2) The secondary
liner layer specified in subsection (1)(a) and (b) of this section may be
substituted for by a naturally occurring material as specified in Section 1(2)
of this administrative regulation.
(3) The primary
liner shall consist of the following layers, listed from bottom to top:
(a) A thirty-six
(36) inch clay layer with a permeability of 1 x 10-7 centimeters per
second as specified in Sections 4, 6 and 7 of this administrative regulation;
(b) A primary
synthetic liner as specified in Section 5 of this administrative regulation;
(c) A twelve (12)
inch drainage layer with permeability of 1 x 10-2 centimeters per
second or a layer of equivalent performance as specified in Section 6 of this
administrative regulation; and
(d) A filter fabric
or other material approved by the cabinet to protect the integrity of the
drainage layer.
Section 3. Specific
Landfill Subgrade Requirement. The landfill subgrade is the uppermost in situ
rock layer, in situ soil layer or select fill that shall be graded and prepared
for landfill construction. For lateral expansions adjacent to existing
landfills, the cabinet may approve encroachment upon the existing landfill's
side slope if a leachate barrier system is designed and construction to
intercept leachate and prevent its migration into the existing landfill.
(1) Materials
required. The landfill subgrade material shall be free of organic material and
consist of bedrock, on-site soils, or any select fill with the structural
ability to support the landfill maximum load with a factor of safety of two
(2.0).
(2) Construction
requirements. The landfill subgrade shall be graded in accordance with the
requirements of the approved engineering plans, report, and specifications. The
material shall be sufficiently dry and structurally sound to ensure that the
first lift and all succeeding lifts of soil placed over the landfill subgrade
can be adequately compacted to the design requirements.
(3) Certification
requirements. At a minimum, the subgrade surface shall be inspected in
accordance with the following requirements:
(a) Before placing any
material over the subgrade, the project engineer shall visually inspect the
exposed surface to evaluate the suitability of the subgrade and ensure that the
surface is properly compacted, smooth, uniform, and has positive surface
drainage;
(b) Soil subgrade
shall be proof-rolled using a minimum 100,000 pound loaded four (4) tire
scraper (twenty (20) cubic yard size) or equivalent procedure and equipment
approved by the cabinet;
(c) Soil subgrade
shall be tested for density and moisture content at a minimum frequency of nine
(9) tests per acre. The subgrade shall be compacted to a density of at least
ninety (90) percent of the standard proctor; and
(d) Sufficient cross
sections shall be taken showing the finished elevation of the completed
subgrade, referenced to existing site control. These cross sections shall serve
as documentation and reference data for all future volume calculations.
Section 4. Specific
Soil Component Requirements of Landfill Liner Systems. The soil component of
the landfill liner system shall be a continuous layer of low permeability soil
constructed to control fluid migration.
(1) Low permeability
soil components shall have a maximum remolded coefficient of permeability of 1
x 10-7 centimeters per second. The soil shall be placed without
damaging any collection and removal system components. The soil material shall
be substantially free of tree roots, wood or other decayable materials and
large rock. The soils shall be compacted to a minimum of ninety-two (92)
percent of the standard proctor density.
(2) Construction
requirements. The project engineer shall ensure that the soil component of the
liner system installation conforms to the following minimum requirements:
(a) The soil
component of the liner system shall be placed on a slope of no less than three
(3) percent toward the main leachate collection line and one (1) percent along
the main leachate collection line to promote positive drainage across the liner
surface and at a maximum slope not greater than fifty (50) percent.
(b) Compaction shall
be performed by properly controlling the moisture content, lift thickness, and
other necessary details to obtain the density, moisture and permeability
characteristics specified in 401 KAR Chapter 48. The maximum final compacted
thickness of each lift of soil material shall be six (6) inches or the
thickness necessary to protect the integrity of underlying components and
achieve the required liner performance standards.
(c) During
construction the moisture content of the soil component of the liner system
shall be maintained within the range identified in accordance with the
certification requirements to ensure that the remolded lift attains the
required permeability.
(3) Certification
requirements. The project engineer shall include in the construction
certification report a discussion of all required quality assurance and quality
control testing. The testing procedures and protocols shall be submitted and
approved by the cabinet. The results of all testing shall be included in the construction
certification report including documentation of any failed test results,
descriptions of the procedures used to correct the improperly installed
material, and statements of all retesting performed in accordance with the
following requirements:
(a) The project
engineer shall certify the results of the quality control testing of any soil
liner materials. The intent of the quality control testing is to ensure that
the specified material meets the permeability requirements of subsection (1) of
this section. Before and during construction of the soil component of the liner
system, the following minimum testing and classification shall be performed:
1. Determination of
the classification of soils for engineering purposes using test methods
approved by the cabinet for each 10,000 cubic yards of soil material placed and
each time significant soil material changes are noted:
2. One (1) analysis
of soil particle size for every 2,000 cubic yards of soil liner material placed
from the same source. Additional analyses shall be performed if the source of
material is changed or if a different soil type is encountered from the same
source.
3. One (1) Atterberg
limits analysis of plastic and liquid limit and plasticity index as approved by
the cabinet for every 2,000 cubic yards of soil liner material placed;
4. One (1) moisture
content test for every 2,000 cubic yards of material placed; and
5. A minimum of one
(1) comparison of the moisture-density-permeability relation for every 20,000
cubic yards of material placed and one (1) each time soil material changes are
noted. A minimum of three (3) laboratory permeability tests shall be performed
using a triaxial cell with backpressure. The specimen used for each
permeability test shall be remolded at the same moisture content which shall be
equal to or not greater than four (4) percent above the optimum moisture
content. The comparison shall be based on a semilog plot of percent maximum
density versus permeability with at least one (1) point below and one (1) point
above the target permeability value.
(b) Quality
assurance testing included in this paragraph shall be compared to and evaluated
against the quality control testing of paragraph (a) of this subsection where
applicable. Quality assurance testing shall include:
1. At least nine (9)
density tests per acre per lift of soil material placed;
2. A minimum of nine
(9) moisture content tests per acre per lift of soil material placed; and
3. All
moisture-density testing performed using nuclear methods.
Section 5. Specific
Synthetic Liner Requirements. A synthetic liner is a low permeability manmade
material having a maximum coefficient of permeability of 1 x 10-12
centimeters per second and is used to control fluid migration from landfills.
(1) Materials required.
The synthetic liner material shall have a demonstrated hydraulic conductivity
less than 1 x 10-12 centimeters per second and chemical and physical
resistance not adversely affected by waste placement or leachate generated and
a maximum water vapor transmission rate of 0.04 grams per square meter per day
for forty (40) mil nominal thickness material and 0.03 grams per square meter
per day for sixty (60) mil nominal thickness material. Documentation shall be
submitted to ensure chemical compatibility of the synthetic liner material
chosen or, in absence of the appropriate documentation, chemical compatibility
testing shall be performed using a test method acceptable to the cabinet.
(2) Construction
requirements. Synthetic liners shall be installed in accordance with the
requirements of the approved engineering plans, report, and specifications and
manufacturer's recommendations. The project engineer shall ensure that the
synthetic liner installation, at a minimum, shall conform with the following:
(a) The synthetic
liner shall have a nominal thickness of sixty (60) mils;
(b) The synthetic
liner shall be installed on a subgrade that has a minimum three (3) percent
slope to promote positive drainage;
(c) Synthetic liners
installed on slopes greater than twenty-five (25) percent shall be designed to
withstand the calculated tensile forces acting upon the synthetic material, and
shall ensure that overall slope stability is maintained;
(d) The surface of
the supporting soil above which the synthetic liner shall be installed shall be
reasonably free of stones, organic matter, irregularities, protrusions, loose
soil, and any abrupt changes in grade that may damage the synthetic liner. The
supporting soil shall conform to the requirements of Section 4 of this administrative
regulation;
(e) The anchor
trench shall be excavated to the length and width prescribed on the approved
design drawings;
(f) Field seams
shall be oriented parallel to the line of maximum slope, i.e., oriented along,
not across the slope. In corners and irregularly-shaped locations, the number
of field seams shall be minimized;
(g) The materials
shall be seamed using an appropriate method acceptable to the cabinet. Seam
testing shall be in accordance with the requirements of subsection (3) of this
section;
(h) The seam area
shall be free of moisture, dust, dirt, debris, and foreign material of any kind
before seaming; and
(i) Field seaming
shall be prohibited when the conditions including ambient air, temperature,
precipitation, and wind do not meet the engineers recommendations based upon
the suppliers specifications.
(3) Certification
requirements. The project engineer shall include in the construction
certification report a discussion of the approved data resulting from the
quality assurance and quality control testing required in this paragraph. The
results of all testing shall be included in the construction certification
report including documentation of any failed test results, descriptions of the
procedures used to correct the failed material, and statements of all retesting
performed.
(a) The project
engineer shall certify the quality control testing of the synthetic liner
ensuring that the material and workmanship meet the requirements of the
approved engineering plans, reports, and specifications. Before installing a
synthetic liner, the following information shall be available to the project
engineer for approval:
1. Origin and
identification of the raw materials used to manufacture the synthetic liner;
2. Copies of quality
control certificates issued by the producer of the raw materials used to
manufacture the synthetic liner; and
3. Reports of tests
conducted to verify the quality of the raw materials used to manufacture the
synthetic liner. Tests for specific gravity, melt flow index, and percent
carbon black shall be performed using a method acceptable to the cabinet.
(b) The project
engineer shall verify through appropriate documentation that the quality
control testing of any synthetic rolls fabricated into blankets at the factory
took place in accordance with the following requirements:
1. The synthetic
liner was continuously inspected for uniformity, damage, imperfections, holes,
cracks, thin spots, and foreign materials. Additionally, the synthetic liner
shall be inspected for tears, punctures, and blisters. Any imperfections shall
be immediately repaired and reinspected;
2. Nondestructive
seam testing was performed on all fabricated seams over their full length using
a test method acceptable to the cabinet; and
3. A destructive
seam testing was performed on a minimum of two (2) samples per blanket. The
samples shall be taken from extra material at the beginning or end of blanket
seams such that the blanket is not damaged and the blanket geometry is not
altered. The size of the sample taken shall be large enough to perform the
required testing. An independent laboratory acceptable to the cabinet shall
perform the required testing on the samples taken. If a sample fails a
destructive test, the entire seam length shall be reconstructed or repaired
using a method acceptable to the cabinet and retested using nondestructive seam
testing over its full length using a test method acceptable to the cabinet.
(c) Quality
assurance testing performed in the field under the supervision of the project
engineer shall assure conformity of the synthetic liner installation with the
engineering plans, reports, and specifications submitted in accordance with the
following requirements:
1. During the
construction phase, the synthetic liner shall be inspected for uniformity,
damage, and imperfections. The liner shall be inspected for tears, punctures,
or blisters. Any imperfections shall be immediately repaired and reinspected;
2. All field seams
shall be nondestructively tested in accordance with the procedures listed in
this clause using a test method acceptable to the cabinet. The project engineer
shall supervise all nondestructive testing; record the location, date, test
unit number, name of tester, and results of all testing; inform the installer
of any required repairs; and overlay all seams which cannot be nondestructively
tested with the same synthetic liner. The seaming and patching operation shall
be inspected by the project engineer for uniformity and completeness; and
3. Destructive testing
shall be performed on the synthetic liner seam sections in accordance with the
following requirements and using test methods acceptable to the cabinet. Seam
samples for testing shall be taken as follows: a minimum of one (1) test per
every 500 feet of seam length unless a more frequent testing protocol is agreed
upon by the installer and project engineer; additional test locations may be
determined during seaming at the project engineer's discretion; and all test
locations shall be appropriately documented. The project engineer shall approve
the sample size to be taken. The sample size shall be predetermined as being
large enough to perform the required testing. An independent laboratory
acceptable to the cabinet shall perform the required testing which shall
include, as a minimum, testing for seam strength and peel adhesion using
testing procedures acceptable to the cabinet. If a sample fails destructive
testing the project engineer shall ensure that the seam is reconstructed
between the location of the sample which failed and the location of the next
acceptable sample; or the welding path is retraced to an intermediate location
at least ten (10) feet from the location of the sample which failed the test,
and a second sample is taken for an additional field test. If this second test
sample passes, the seam shall then be reconstructed between the location of the
second test and the original sampled location. If the second sample fails, this
process shall be repeated. All acceptable seams shall lie between two (2)
locations where samples passed the required test procedures of this section and
include one (1) test location along the reconstructed seam.
Section 6. Primary
Liner System. The liner shall be designed using the following specifications:
(1) A thirty-six
(36) inch thick low permeability soil layer having a remolded coefficient of
permeability of 1 x 10-7 centimeters per second and compacted to a
minimum of ninety-two (92) percent standard proctor density;
(2) A sixty (60) mil
thick synthetic liner having a maximum coefficient of permeability of 1 x 10-12
centimeters per second and not adversely affected by the leachate or loading
from the operational landfill;
(3) A leachate
collection and removal system consisting of a twelve (12) inch thick granular
material layer with a leachate collection pipe network. This collection system
shall be designed to achieve a maximum hydraulic head on the primary composite
liner no greater than twelve (12) inches. The granular material shall have a
minimum coefficient of permeability of 1 x 10-2 centimeters per
second. The physical and chemical properties of the granular material and pipe
shall not be adversely affected by the loads or leachate generated by the
operations of the landfill. Alternate materials proposed to function as a
substitute for the granular soil layer shall be demonstrated to be equivalent
in performance for leachate drainage and load bearing properties; and
(4) The leachate
collection system shall contain a perforated piping system capable of removing
leachate from the top surface of the low permeability solid component, and
conveying it to a collection point. The drainage system shall meet the
following requirements:
(a) Main leachate
collection pipes shall have a minimum diameter of eight (8) inches and shall be
designed to withstand static and dynamic loads that may be encountered;
(b) The sheet flow
drainage distances to the lateral drainage pipes shall not exceed fifty (50)
feet;
(c) The lateral
pipes shall be installed primarily perpendicular to flow;
(d) The minimum
diameter of lateral perforated pipes shall be four (4) inches and shall be
designed to withstand static and dynamic loads that may be encountered. The
materials used shall at a minimum conform to the specifications for ASTM
schedule eighty (80) pipe;
(e) The minimum
slope for the piping system shall be one (1) percent;
(f) The leachate
collection tank shall be a minimum of 1,000 gallons. Additional capacity shall
be provided to store leachate for a minimum of fifteen (15) days production at
peak production rates during operation and closure;
(g) The method of
leachate disposal shall be described. When it is discharged to the sediment
structure, a treatment plant is proposed or other method of discharge is
proposed, the KPDES permit shall reflect this provision. When an off-site
wastewater treatment plant is used, the applicant shall provide written
documentation showing the acceptance of the waste. The criteria for disposal at
the wastewater treatment plant shall be stated. The leachate collection system
shall have a method to measure the quantity of leachate managed at the site;
(h) The leachate
collection pipe system shall be designed to allow internal inspection, cleaning
and maintenance; and
(i) The maximum
design head of the leachate collection system shall be one (1) foot.
(5) A geosynthetic
filter fabric or other suitable material shall be placed above the drainage
layer to prevent clogging.
Section 7. Slope
Considerations. (1) For bottom slopes of less than or equal to ten (10)
percent, the owner or operator shall have a liner system meeting the
requirements of Section 1 of this administrative regulation.
(2) For bottom
slopes of ten (10) to twenty-five (25) percent, the owner or operator shall
have a liner system meeting the requirements of Section 2(3) of this
administrative regulation, except that the owner or operator may replace the
granular soil layers in the leachate collection and hydraulic relief systems
with synthetic drainage netting.
(3) For bottom
slopes of more than twenty-five (25) percent, the thickness of the soil
required in Sections 2(3)(a) and (6)(1) of this administrative regulation shall
be reduced by no more than twelve (12) inches.
Section 8. Final Cap
System. At a minimum the final cap shall consist of a layered system. Each
layer shall have the same slope of between five (5) and twenty-five (25)
percent. The components, listed from bottom to top, are:
(1) A filter fabric
or other material approved by the cabinet;
(2) A twelve (12) inch
sand gas venting system with a minimum hydraulic permeability of 1 x 10-3;
(3) A filter fabric
or other material approved by the cabinet;
(4) An eighteen (18)
inch clay layer with a maximum permeability of 1 x 10-7 centimeters
per second;
(5) For areas of the
final cap with a slope of less than fifteen (15) percent, a twelve (12) inch
drainage layer with a minimum permeability of 1 x 10-3 centimeters
per second; and
(6) A thirty-six
(36) inch vegetative soil layer.
Section 9. Final Cap
System Specifications. The specifications for final cap component layers are:
(1) A low
permeability clay layer listed in Section 8(4) of this administrative
regulation shall be compacted to a minimum of ninety-two (92) percent of the
standard proctor density;
(2) A drainage layer
specified in Section 8(5) of this administrative regulation shall be compacted
to a minimum of eighty-five (85) percent of the standard proctor density. Field
tile drainage shall be specified as necessary to relieve water captured by this
drainage layer;
(3) A vegetative
soil layer as specified in Section 8(6) of this administrative regulation shall
be sufficient to sustain vegetative growth and prevent root penetration of the
underlying layers. A thicker layer may be required by the cabinet to properly
retain moisture or meet closure care requirements.
(4) Drainage berms
of at least one (1) foot in height or two (2) feet in width shall be placed at
the following intervals for the following slopes:
(a) 150 feet at
greater than ten (10) percent slope;
(b) 200 feet at
slope between five (5) and ten (10) percent. In lieu of drainage berms, the
owner or operator may substitute a design with a horizontal terrace of at least
fifteen (15) feet width on the slope for every twenty-five (25) feet maximum
rise in elevations on the slope. The slope of the terrace shall be five (5)
percent into the fill and drainage ditches shall be designed for each terrace
to convey precipitation flows. The maximum slope between terraces shall not
exceed twenty-five (25) percent; or
(c) The applicant
shall may adjust the drainage berm specifications with design calculations
based upon characteristics of soils and cover.
(5) A synthetic
liner with a minimum thickness of forty (40) mils and a maximum coefficient of
permeability of 1 x 10-12 centimeters per second may be substituted
for the low-permeability soil cover in Section 8(4) of this section.
(6)(a) The final
cover shall be revegetated.
(b) The soil-water
pH shall be adjusted and the soil fertilized based upon current soil test
results.
(c) The seed bed
shall be prepared and temporary nurse crops and permanent grasses planted in
accordance with the approved closure plan within thirty (30) days of completion
of final cover grading.
(d) The owner or
operator shall repeat the above as necessary to achieve permanent vegetation.
(e) Erosion controls
shall be addressed in the closure plan and constructed as required. All slopes
over three (3) percent shall have controls applied at the time of seeding.
(f) The owner or
operator shall inspect all areas and perform maintenance and revegetation. At a
minimum, the site shall be initially inspected according to this table:
Seeding
Date
Follow-up
Inspection
Date
Complete
Revegetation
By
Aug.
16-Oct. 15
April
1
June
15
Oct.
16-Mar. 15
June
1
June
30
Mar.
16-Jun. 15
September
1
October
15
Jun.
16-Aug. 15
October
1
October
30
After the initial
inspection, follow-up inspections shall be made on April 1, and September 1,
with revegetation completed by June 15 and October 15.
(g) After one (1)
year, all areas larger than 100 square feet with less than forty (40) percent
vegetation shall be tested to determine required revegetation, which shall be
completed by September 30.
Section 10.
Structural Integrity of Cap and Liner. The design engineer shall analyze the
structural integrity of the site, the subbase, each component of the composite
liner, each component of the final cover, the composite liner system and the
final cap as a system. Modifications to the design shall be provided where
necessary, to achieve a minimum factor of safety of two (2) for the subbase,
one and one-fourth (1.25) for the structural design of the facility liner
components, and one and one-half (1.5) for the final cover system. Synthetic
liner material and structural synthetic materials shall be designed for a
maximum elongation of ten (10) percent.
Section 11.
Alternative Specifications. Alternative specifications may be used only after
approval by the cabinet upon a demonstration by a qualified registered
professional engineer that they shall result in performance with regard to
safety, stability and environmental protection equal to or better than that
resulting from designs complying with the specifications of this administrative
regulation. (16 Ky.R. 1776; Am. 2211; 2374; eff. 5-8-90.)