Current through Register Vol. 41, No. 3, September 23, 2024
The design and construction of all sanitary, CDD and
industrial landfills shall be governed by the standards set forth in this
section.
A. Both the landfill capacity
(in cubic yards) and the daily disposal limit shall be specified.
B. All facilities shall be surrounded on all
sides by natural barriers, fencing, or an equivalent means of controlling
vehicular and public access and preventing illegal disposal. All access will be
limited by gates, and such gates shall be securable and equipped with locks,
except, in the case of industrial disposal sites where the solid waste disposal
landfill is on site of the industrial facility where access is
limited.
C. All landfill access
roads shall be provided with a base capable of withstanding anticipated heavy
vehicle loads and shall be all-weather roads extending from the entrance of the
landfill to the working face.
D.
All facilities, except captive industrial, shall have an adequately lighted and
heated shelter where operating personnel can exercise site control and have
access to essential sanitation facilities. Lighting, heat, and sanitation
facilities may be provided by portable equipment as necessary.
E. Aesthetics shall be considered in the
design of a landfill or site. Use of artificial or natural screens shall be
incorporated into the design for site screening and noise attenuation. The
design shall reflect those requirements, if any, that are determined from the
long-range plan for the future use of the site. Noise attenuation shall be less
than 80 dBA at the facility boundary.
F. All landfills shall be equipped with
permanent or mobile telephone or radio communications except at industrial
landfills where other onsite resources are available.
G. Two survey benchmarks shall be established
and maintained on the landfill site, and their location identified or recorded
on drawings and maps of the landfill.
H. Surface water runoff. Facilities shall be
designed to provide and maintain:
1. A run-on
control system to prevent flow onto the active portion of the landfill during
the peak discharge from a 24-hour, 25-year storm;
2. A run-off control system from the active
portion of the landfill to collect and control at least the water volume
resulting from a 24-hour, 25-year storm. Run-off from the active portion of the
landfill unit shall be handled in a manner that will not cause the discharge
of:
a. Pollutants into waters of the United
States, including wetlands, that violates any requirements of the Clean Water
Act, including, but not limited to, the Virginia Pollutant Discharge
Elimination System (VPDES) requirements; and
b. A nonpoint source of pollution to waters
of the United States, including wetlands, that violates any requirement of an
areawide or statewide water quality management plan that has been approved
under § 208 or 319 of the Clean Water Act, as amended; and
3. Drainage structures shall be
installed and continuously maintained to prevent ponding and erosion, and to
minimize infiltration of water into solid waste cells.
I. A fire break of 50 feet shall be designed
between the limits of waste and all tree lines.
J. Bottom liner.
1. Sanitary landfills.
All sanitary landfills shall be underlain by a composite
liner system as follows:
a. Subtitle D
Liner System.
(1) Base preparation to protect
the liner by preventing liner failure through subsidence or structural failure
of the liner system.
(2) A lower
liner consisting of at least a two-foot layer of compacted soil or augmented
soil with a hydraulic conductivity of no more than
1x10-7 cm/sec.
(3) An upper component consisting of a
minimum 30 mil flexible membrane liner (FML). If high density polyethylene
(HDPE) is used as an FML, it shall be at least 60 mil thick. The FML component
shall be:
(a) Installed in direct and uniform
contact with the compacted soil liner;
(b) Placed in accordance with an approved
construction quality control/quality assurance program submitted with the
design plans; and
(c) Placed with a
minimum of 2.0% slope for leachate drainage.
b. Alternate Liner System. FML/Geosynthetic
Clay Liner (GCL).
(1) The alternate liner
system presented below is the minimum that is required under these regulations
requiring no demonstration. If additional components to this alternate system
are incorporated into the liner design, no demonstration will be
required.
(2) A controlled subgrade
with a minimum thickness of 12 inches shall be provided immediately beneath the
alternate liner. The controlled subgrade shall consist of soils having a
Unified Soil Classification of SC, ML, CL, MH, or CH and shall be compacted to
a minimum of 95% of the maximum dry density, as determined by ASTM D698
(Standard Proctor). The surface shall be rolled smooth and be free of rocks or
stones in excess of 0.75 inches prior to placement of the overlying GCL.
The surface shall be prepared to meet the liner
manufacturer's and the installer's specifications. The liner
manufacturer's/installer's specifications shall consider compaction, soft
areas, proof rolling, maximum grain size, rocks, and other subgrade
imperfections that may affect the liner. The liner installer shall provide
written acceptance of the subgrade before installing liner on it.
(3) A lower liner consisting of
geosynthetic clay liner (GCL) with a hydraulic conductivity of no more than
1x10-9 cm/sec. The GCL shall have appropriate
overlap between adjacent panels so as to minimize the risk of panel shrinkage
and/or transverse shortening creating panel separation, and be installed with a
minimum 12-inch overlap on the panel ends and 6-inch overlap between adjacent
panels. If the liner system will be exposed prior to the placement of a
protective cover layer for periods in excess of two months, a discussion of the
adequacy of the GCL overlap shall be included in the certification report.
Granular bentonite shall be spread on all seams prior to placement of
overlapping panels, or other means per manufacturer's specifications.
(4) An upper component consisting of a
minimum 30 mil flexible membrane liner (FML). If high density polyethylene
(HDPE) is used as an FML, it shall be at least 60 mil thick. The FML component
shall be:
(a) Installed in direct and uniform
contact with the GCL;
(b) Placed in
accordance with an approved construction quality control/quality assurance
program submitted with the design plans;
(c) Placed with a minimum of 2.0% slope for
leachate drainage; and
(d) Leachate
collection aggregate/protective cover materials shall be placed as soon as
practical following the completion of the FML installation. At a minimum, this
material should be placed within three months of final acceptance of the FML
surface by the CQA engineer.
c. Additional alternate liner systems.
(1) Additional alternate liner systems may be
approved if the owner or operator of the landfill demonstrates to the
satisfaction of the director that the proposed alternate liner system design
will ensure that the maximum contaminant levels (MCL) promulgated under §
1412 of the Safe Drinking Water Act ( 40 CFR Part 141) will not be exceeded in
the uppermost aquifer at the disposal unit boundary.
(a) The demonstration shall be based on the
consideration of the following factors:
(1)
The hydrogeologic characteristics of the landfill and surrounding
land;
(2) The climatic factors of
the area;
(3) The volume and
physical and chemical characteristics of the leachate;
(4) The quantity, quality, and direction of
flow of groundwater;
(5) The
proximity and withdrawal rate of the groundwater users;
(6) The availability of alternative drinking
water supplies;
(7) The existing
quality of the groundwater, including other sources of contamination and their
cumulative impacts on the groundwater, and whether the groundwater is currently
used or reasonably expected to be used for drinking water;
(8) Public health, safety, and welfare
effects; and
(9) Practicable
capability of the owner or operator.
(b) The demonstration shall be supported by
the results of a mathematical modeling study based on the EPA MULTIMED
model.1 Other models may be used if accompanied by
justification describing the reasons for inapplicability of the MULTIMED
model.2
1Sharp-Hansen, S., C. Travers,
P. Hummel, T. Allison, R. Johns, and W. B. Mills. A Subtitle D Landfill
Application Manual for the Multimedia Exposure Assessment Model (MULTIMED 2.0),
United States Environmental Protection Agency, Athens, Georgia, 1995.
2For a listing and review of
models see Travers, C.L., and S. Sharp-Hansen, Leachate Generation and
Migration at Subtitle D Facilities: A Summary and Review of Processes and
Mathematical Models, United States Environmental Protection Agency,
Environmental Research Laboratory, Athens, Georgia (1991).
2. CDD and
industrial landfills.
All landfills shall be underlain by a liner system as
follows:
a. Compacted clay:
(1) A liner consisting of at least one-foot
layer of compacted soil with a hydraulic conductivity of no more than
1x10-7 cm/sec.
(2) The liner shall be placed with a minimum
of 2.0% slope for leachate drainage.
(3) The liner shall be covered with a minimum
one-foot thick drainage layer.
b. Synthetic liners:
(1) Synthetic liner consisting of a minimum
30 mil thick flexible membrane. If high density polyethylene is used, it shall
be at least 60 mil thick. Synthetic liners shall be proven to be compatible
with the solid waste and its leachate.
(2) The liner shall be placed in accordance
with an approved construction quality control/quality assurance program
submitted with the design plans.
(3) The surface under the liner shall be a
smooth rock-free base or otherwise prepared to prevent liner failure.
(4) The liner shall be placed with a minimum
of 2.0% slope for leachate drainage.
(5) The liner shall be covered with a 12-inch
thick drainage layer for leachate removal and a six-inch thick protective layer
placed above the drainage layer, both composed of materials with a hydraulic
conductivity of 1x10-3 cm/sec or greater (lab
tested).
c. Other
liners:
(1) Other augmented compacted clays or
soils may be used as a liner provided the thickness is equivalent and the
hydraulic conductivity will be equal to or less than that for compacted clay
alone.
(2) The effectiveness of the
proposed augmented soil liner shall be documented by using laboratory
tests.
(3) The liner shall be
placed with a minimum of 2.0% slope for leachate drainage.
d. In-place soil:
(1) Where the landfill will be separated from
the groundwater by low hydraulic conductivity soil as indicated by laboratory
tests, which is natural and undisturbed, and provides equal or better
performance in protecting groundwater from leachate contamination, a liner can
be developed by manipulation of the soil to form a liner with equivalent
thickness and hydraulic conductivity equal to or less than that of the clay
liner.
(2) The liner shall be
prepared with a minimum of 2.0% slope for leachate drainage. Interior liner
slopes of 33% will be allowed provided that adequate runoff and erosion
controls are established. All interior slopes shall be supported by necessary
calculations and included in the design manual.
e. Double liners required or used in lieu of
groundwater monitoring shall include:
(1) Base
preparation to protect the liner.
(2) A bottom or secondary liner that is soil,
synthetic, or augmented soil as indicated in subdivision 2 a, b, c, or d of
this subsection.
(3) A witness or
monitoring zone placed above the bottom or secondary liner consisting of a
12-inch thick drainage layer composed of material with a hydraulic conductivity
of 1x10-3 cm/sec or greater (lab tested) with a
network of perforated pipe, or an equivalent design.
(4) The primary liner as indicated in
subdivision 2 a, b, or c of this subsection.
(5) The primary liner will be covered with a
minimum 12-inch thick drainage layer and a six-inch thick protective layer,
placed above the drainage layer, both composed of materials having a hydraulic
conductivity of 1x10-3 cm/sec or greater (lab
tested).
(6) A program for
monitoring the witness zone shall be established. The program will monitor the
quantity and quality of liquids collected from this zone and shall be designed
to detect waste constituents most likely associated with the waste accepted at
the landfill. The program will also establish a leakage action rate beyond
which groundwater contamination will be assessed through a groundwater
monitoring program in accordance with
9VAC20-81-250.
f. If five-foot separation from seasonal high
ground water can be demonstrated, a separate area may be established to receive
only stumps, brush, leaves, and land-clearing debris. Such an area may be
constructed without a liner or a leachate collection system, but may not
receive any other solid waste.
K. Each site design shall include a
decomposition gas venting system or gas management system (see
9VAC20-81-200) , except at CDD and
industrial landfills if the owner or operator can demonstrate to the department
that gas formation is not a concern.
L. Leachate control and monitoring systems
are subject to the requirements in
9VAC20-81-210.
M. A groundwater monitoring system shall be
installed at all landfills in accordance with
9VAC20-81-250, except for the
exemption of double-lined CDD or industrial landfills referenced in this
section.
N. Final contours of the
finished landfill shall be specified. Design of final contours shall consider
subsequent site uses, existing natural contours, surface water management
requirements, and the nature of the surrounding area. The final elevation of
the landfill shall be limited by the structural capacity of the liner and
leachate collection and removal system and by stability of foundation and
slopes. The final contour shall not cause structural damage or collapse of the
leachate collection system.
O.
Finished side slopes shall be designed as set forth in
9VAC20-81-160 D 3 of this
part.
P. All landfills shall be
constructed in accordance with approved plans, which shall not be subsequently
modified without approval by the department.
Q. Construction quality assurance program.
1. General.
a. A construction quality assurance (CQA)
program is required for all landfill units. The program shall ensure that the
constructed unit meets or exceeds all design criteria and specifications in the
permit. The program shall be developed and implemented under the direction of a
CQA officer who is a professional engineer.
b. The CQA program shall address the
following physical components, where applicable:
(1) Foundations;
(2) Low-hydraulic conductivity soil
liners;
(3) Synthetic membrane
liners;
(4) Leachate collection and
removal systems including an 18-inch protective layer;
(5) Gas management components; and
(6) Final cover systems.
2. Written CQA plan. The owner or
operator shall develop and implement a written CQA plan that shall include
observations, inspections, tests, and measurements. The plan shall identify
steps that will be used to monitor and document the quality of materials and
the condition and manner of their installation. The CQA plan shall include:
a. Identification of applicable units, and a
description of how they will be constructed;
b. Identification of key personnel in the
development and implementation of the CQA plan, and CQA officer
qualifications;
c. A description of
inspection and sampling activities for all unit components identified in
subdivision 1 b of this section including observations and tests that will be
used before, during, and after construction to ensure that the construction
materials and the installed unit components meet the design specifications. The
description shall cover sampling size and locations; frequency of testing; data
evaluation procedures; acceptance and rejection criteria for construction
materials and constructed components; plans for implementing corrective
measures; and data or other information to be recorded;
d. Structural stability and integrity of all
components of the unit identified in subdivision 1 b of this
subsection;
e. Proper construction
of all components of the liners, leachate collection and removal system, gas
management system if required under subsection K of this section, and final
cover system, according to permit specifications and good engineering
practices, and proper installation of all components (e.g., pipes) according to
design specifications;
f.
Conformity of all materials used with design and other material
specifications;
g. The permeability
of the soil liner.
(1) The ability of the soil
to be used as a liner material must be demonstrated using a test pad. At least
one test pad shall be required for every source of low permeability liner soil.
If soil sources are consistent (i.e. similar USCS soil type, liquid and plastic
limits, grain size distribution, moisture density relationship, and
permeability characteristics) one test pad will be adequate provided that the
third-party quality control firm agrees. In the event that soils are not
uniform within a borrow source an additional test pad shall be constructed for
each soil type.
The test pad shall establish the range of criteria
(compaction, moisture content, USCS classification, and grain size) that can be
expected to achieve a low permeability soil liner meeting the requirements of
the permit. To achieve these results the test pad's permeability shall be
correlated with grain size analysis, liquid and plastic limits, moisture
content, relative compaction, remolded permeability, undisturbed Shelby tube
sample permeability, and the in-situ permeability determined by field tests
performed on the test pad.
(2) Following the completion of the test pad
the remaining low permeability liner system shall be certified by testing the
constructed liner to determine its conformance to the acceptable criteria
established during the test pad construction. Such tests shall include
compaction, moisture content, grain size, and the liquid and plastic limits of
the soil. Any area that does not conform to the established criteria shall be
further tested by obtaining an undisturbed Shelby tube sample of the
constructed liner and performing a laboratory permeability on it. In addition
to testing any liner areas that do not conform to the established test pad
acceptance criteria, a minimum of one additional laboratory permeability test
shall be performed on each acre of constructed liner.
3. Certification. Once
construction is complete, the owner or operator shall submit to the department
by certified mail or other equivalent method with a return receipt or hand
delivery a certification signed by the CQA officer that the approved CQA plan
has been successfully carried out and that the unit meets the requirements of
this section. Documentation supporting the CQA officer's certification shall be
submitted to the department upon request. An additional professional engineer's
certification is required under the provisions of
9VAC20-81-490 A. Wastes shall not
be accepted until the facility receives a Certificate to Operate (CTO) per
9VAC20-81-490 A.
Statutory Authority
§ 10.1-1402 of the Code of Virginia; 42 USC §
6941 et seq.; 40 CFR Part 258.
