Current through Register Vol. 41, No. 3, September 23, 2024
A. Each owner seeking to comply with
9VAC5-40-5820 C 2 a shall site
active collection wells, horizontal collectors, surface collectors, or other
extraction devices at a sufficient density throughout all gas producing areas
using the following procedures unless alternative procedures have been approved
by the board as provided in
9VAC5-40-5820 C 2 a (3) and (4):
1. The collection devices within the interior
and along the perimeter areas shall be certified to achieve comprehensive
control of surface gas emissions by a professional engineer. The following
issues shall be addressed in the design: depths of refuse, refuse gas
generation rates and flow characteristics, cover properties, gas system
expandability, leachate and condensate management, accessibility, compatibility
with filling operations, integration with closure end use, air intrusion
control, corrosion resistance, fill settlement, and resistance to the refuse
decomposition heat.
2. The
sufficient density of gas collection devices determined in subdivision A 1 of
this section shall address landfill gas migration issues and augmentation of
the collection system through the use of active or passive systems at the
landfill perimeter or exterior.
3.
The placement of gas collection devices determined in subdivision A 1 of this
section shall control all gas producing areas, except as provided by
subdivisions A 3 a and A 3 b of this section.
a. Any segregated area of asbestos or
nondegradable material may be excluded from collection if documented as
provided under
9VAC5-40-5890 F. The documentation
shall provide the nature, date of deposition, location and amount of asbestos
or nondegradable material deposited in the area, and shall be provided to the
board upon request.
b. Any
nonproductive area of the landfill may be excluded from control, provided that
the total of all excluded areas can be shown to contribute less than 1.0% of
the total amount of NMOC emissions from the landfill. The amount, location, and
age of the material shall be documented and provided to the board upon request.
A separate NMOC emissions estimate shall be made for each section proposed for
exclusion, and the sum of all such sections shall be compared to the NMOC
emissions estimate for the entire landfill. Emissions from each section shall
be computed using the following equation:
Qi =
2kL0Mi(e-kti)(CNMOC)(3.6
X 10-9)
where
Qi = NMOC emission rate from the
ith section, megagrams per year
k = methane generation rate constant,
year-1
L0 = methane generation potential,
cubic meters per megagram solid waste
Mi = mass of the degradable solid
waste in the ith section, megagrams
ti = age of the solid waste in the
ith section, years
CNMOC = concentration of
nonmethane organic compounds, parts per million by volume
3.6 X 10-9 = conversion
factor
The values for k and CNMOC
determined in field testing shall be used, if field testing has been performed
in determining the NMOC emission rate or the radii of influence (this is
distance from the well center to a point in the landfill where the pressure
gradient applied by the blower or compressor approaches zero). If field testing
has not been performed, the default values for k, L0 and
CNMOC provided in
9VAC5-40-5860 B 1 or the
alternative values from
9VAC5-40-5860 B 5 shall be used.
The mass of nondegradable solid waste contained within the given section may be
subtracted from the total mass of the section when estimating emissions
provided the nature, location, age, and amount of the nondegradable material is
documented as provided in subdivision A 3 a of this section.
B. Each owner seeking to comply with
9VAC5-40-5820 C 2 a (1) shall
construct the gas collection devices using the following equipment or
procedures:
1. The landfill gas extraction
components shall be constructed of polyvinyl chloride (PVC), high density
polyethylene (HDPE) pipe, fiberglass, stainless steel, or other nonporous,
corrosion-resistant material of suitable dimensions to: convey projected
amounts of gases; withstand installation, static, and settlement forces; and
withstand planned overburden or traffic loads. The collection system shall
extend as necessary to comply with emission and migration standards. Collection
devices such as wells and horizontal collectors shall be perforated to allow
gas entry without head loss sufficient to impair performance across the
intended extent of control. Perforations shall be situated with regard to the
need to prevent excessive air infiltration.
2. Vertical wells shall be placed so as not
to endanger underlying liners and shall address the occurrence of water within
the landfill. Holes and trenches constructed for piped wells and horizontal
collectors shall be of sufficient cross section so as to allow for their proper
construction and completion including, for example, centering of pipes and
placement of gravel backfill. Collection devices shall be designed so as not to
allow indirect short circuiting of air into the cover or refuse into the
collection system or gas into the air. Any gravel used around pipe perforations
should be of a dimension so as not to penetrate or block
perforations.
3. Collection devices
may be connected to the collection header pipes below or above the landfill
surface. The connector assembly shall include a positive closing throttle
valve, any necessary seals and couplings, access couplings and at least one
sampling port. The collection devices shall be constructed of PVC, HDPE,
fiberglass, stainless steel, or other nonporous material of suitable
thickness.
C. Each owner
seeking to comply with
9VAC5-40-5820 C 2 a (1) shall
convey the landfill gas to a control system in compliance with
9VAC5-40-5820 C 2 c through the
collection header pipe(s). The gas mover equipment shall be sized to handle the
maximum gas generation flow rate expected over the intended use period of the
gas moving equipment using the following procedures:
1. For existing collection systems, the flow
data shall be used to project the maximum flow rate. If no flow data exists,
the procedures in subdivision C 2 of this section shall be used.
2. For new collection systems, the maximum
flow rate shall be in accordance with
9VAC5-40-5850 C 1.
Statutory Authority
§ 10.1-1308 of the Code of Virginia; §§
110, 111, 123, 129, 171, 172, and 182 of the Clean Air Act; 40 CFR Parts 51 and
60.
