4&EPA
United States
Environmental Protection
Agency
Air and
Radiation
(6604J)
EPA402-R-93-078
October 1993
(Revised April 1994)
RADON MITIGATION
STANDARDS
Electric Fan
System Failure Warning Device
Vent Pipe Running Between Sub-slab
Gravel and Roof
Sealing and Caulking
Physical Barriers Between Soil and
House Foundation
Recycled/Recyclable
Printed with Soy/Canola Ink on paper that
NHJV-7 contains a< least 5O%recyc9ed fiber
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DISCLAIMER
The U.S. Environmental Protection Agency (EPA) strives to provide accurate, complete, and
useful information. However, neither EPA nor any person contributing to the preparation of
this document makes any warranty, express or implied, with respect to the usefulness or
effectiveness of any information, method, or process disclosed in this material. Nor does
EPA assume any liability for the use of, or for damages arising from the use of, any
information, method, or process disclosed in this document.
Mention of firms, trade names, or commercial products in this document does not constitute
endorsement or recommendation for use.
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CONTENTS
Page
1.0 Background 1
2.0 Purpose 1
3.0 Participants 1
4.0 Scope 1
5.0 Assumption 1
6.0 Implementation 1
7.0 Limitations 2
8.0 Reference Documents 3
9.0 Description of Terms 4
10.0 General Practices 6
11.0 Building Investigation 7
12.0 Worker Health and Safety 9
13.0 Systems Design 10
14.0 Systems Installation 10
14.1 General Requirements 10
14.2 Radon Vent Pipe Installation Requirements 11
14.3 Radon Vent Fan Installation Requirements 12
14.4 Suction Pit Requirement for Sub-Slab Depressurization (SSD) Systems ... 12
14.5 Sealing Requirements 13
14.6 Electrical Requirements 14
14.7 Drain Installation Requirements 14
14.8 HVAC Installation Requirements 15
15.0 Materials 15
16.0 Monitors and Labeling 16
17.0 Post-Mitigation Testing 17
18.0 Contracts and Documentation 17
APPENDIX Mitigation Project Record (Form) A-l
11
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RADON MITIGATION STANDARDS
1.0 BACKGROUND
The 1988 Indoor Radon Abatement Act
(IRAA) required the Environmental
Protection Agency (EPA) to develop a
voluntary program to evaluate and provide
information on contractors who offer radon
control services to homeowners. The Radon
Contractor Proficiency (RCP) Program was
established to fulfill this portion of the
IRAA. In December 1991, EPA published
"Interim Radon Mitigation Standards" as
initial guidelines for evaluating the
performance of radon mitigation contractors
under the RCP Program. Over the past six
years, the effectiveness of the basic radon
mitigation techniques set forth in the,
"Interim Standards" has been validated in
field applications throughout the United
States. This experience now serves as the
basis for the more detailed and final Radon
Mitigation Standards (RMS) set forth in this
document.
2.0 PURPOSE
The purpose of the RMS is to provide radon
mitigation contractors with uniform
standards that will ensure quality and
effectiveness in the design, installation, and
evaluation of radon mitigation systems in
detached and attached residential buildings
three stories or less in height. The RMS is
intended to serve as a model set of
requirements which can be adopted or
modified by state and local jurisdictions to
fulfill objectives of their specific radon
contractor certification or licensure
programs.
3.0 PARTICIPANTS
Minimum requirements are established in
the RMS for individuals nationwide who
perform radon remediation work and wish to
participate in the RCP Program. To
participate in EPA's RCP Program, the
mitigation contractor shall have completed
all RCP training and examination
requirements, be listed in the current RCP
Listing Report, and shall agree to follow the
provisions of the RMS.
4.0 SCOPE
The requirements addressed in the RMS
include the following categories of
contractor activity: General Practices,
Building Investigation, Worker Health and
Safety, Systems Design, Systems
Installation, Materials, Monitors and
Labeling, Post-Mitigation Testing, and
Contracts and Documentation.
5.0 ASSUMPTION
Before applying the provisions of the RMS,
it is assumed that appropriate radon/radon
decay product measurements have been
performed within the structure, and that the
owner has decided that radon remediation is
necessary.
6.0 IMPLEMENTATION
6.1 The RMS includes requirements for
installation of radon remediation systems
and provides a basis for evaluating the
quality of those installations. It may be
adopted by state regulatory agencies for
state or local radon mitigation contractor
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licensure programs. It may also be used as
a reference during inspection of in-progress
or completed radon mitigation work.
6.2 Contractors shall personally conduct
follow-up inspection of any radon mitigation
systems installed by their firm or by
subcontractors to insure conformance with
the requirements of the RMS. This
requirement shall include the post-mitigation
testing prescribed in paragraph 17.0.
6.3 EPA will evaluate reports of non-
compliance with the RMS that are referred
to the Agency by states and other agencies
that monitor radon mitigation services.
Based on its evaluation, EPA may initiate
established RCP program de-listing
procedures against contractors that the
Agency or States (with certification
programs) find are in violation of the
mandatory provisions of the RMS (See
paragraph 6.4). In addition, EPA or its
agent may conduct inspections of radon
mitigation projects. State radon program
personnel or their contracted representatives
are considered EPA agents for conducting
such inspections.
6.4 Those provisions of the RMS that are
considered to be mandatory are prefaced by
the term "shall." Provisions that are
considered good practice but which are not
mandatory are prefaced by the terms
"should" or "recommended."
6.5 The RMS will be updated as
necessary, and in response to technological
advances and field experience.
7.0 LIMITATIONS
7.1 Although the provisions of the RMS
have been carefully reviewed for potential
conflicts with other regulatory requirements,
adherence to the RMS does not guarantee
compliance with the applicable codes or
regulations of any other Federal, state, or
local agency having jurisdiction.
7.2 Where discrepancies exist between
provisions of the RMS and local codes or
regulations, local codes shall take
precedence. However, where compliance
with local codes necessitates a deviation
from the RMS, EPA recommends that RCP
•listed contractors report the deviation in
writing to the appropriate EPA Regional
Office and the appropriate state regulatory
official within 30 days. It should be noted
that EPA is not requiring the reporting that
is recommended in this paragraph. States
with radon contractor certification programs
may require that contractors give prior
notification of their intent to deviate from
the RMS for research or other purposes.
7.3 The RMS is not intended to be used
as a design manual, and compliance with its
provisions will not guarantee reduction of
indoor radon concentrations to any specific
level.
7.4 The RMS shall not apply to radon
mitigation systems installed prior to its
effective date, except when a previously
installed system is altered. "Altering" radon
mitigation systems does not include activities
such as replacing worn out equipment, or
providing new filters, while leaving the
remainder of the system unchanged. Mitiga-
tion systems installed prior to the effective
date of the RMS should be in compliance
with the requirements in force at that time
(i.e. EPA Interim Radon Mitigation Stand-
ards, December 15, 1991, as amended by
the Addendum on Backdrafting of October
1, 1992). If a radon mitigation system is
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found that does not comply with current
standards, contractors should recommend to
clients that the system be upgraded or
altered to meet current standards.
7.5 Because of the wide variation in
building design, size, operation and use, the
RMS does not include detailed guidance on
how to select the most appropriate
mitigation strategy for a given building.
That guidance is provided in the documents
referenced in paragraphs 8.1, 8.2, and 8.3.
7.6 The provisions of the RMS are
limited to proven technologies and methods.
Publication of this standard is not intended,
however, to inhibit research and evaluation
of other innovative radon mitigation
techniques. When such .research is
conducted, a performance standard shall be
applied, i.e., post-mitigation radon levels
shall be at or below EPA's action level
(currently 4 pCi/L), and the systems design
criteria in paragraph 13.0 shall be applied.
Contractors who expect to deviate from
proven radon mitigation technologies and
methods (as defined in the RMS and other
EPA references in Section 8.0) for purposes
of research on innovative mitigation
techniques, shall obtain prior approval from
state regulatory offices, document the non-
standard techniques, and inform the client of
the deviation from standard procedures. In
cases where radon mitigation is not regula-
ted by the state, contractors shall obtain
prior approval from a Regional EPA office.
7.7 At this time, the RMS does not
include standards for installing systems to
mitigate radon in water. However, EPA is
currently developing a standard that will
regulate radon levels in domestic water
supplies. Following publication of that
standard, the RMS may be revised, as
appropriate, to include standards for
installation of systems that are effective in
reducing radon levels in water.
8.0 REFERENCE DOCUMENTS
The following documents are sources of
additional radon mitigation information and
are recommended reading for contractors
participating in the RCP program.
8.1 EPA Training Manual, "Reducing
Radon In Structures," (Third Edition),
January 1993.
8.2 "Radon Reduction Techniques for
Detached Houses, Technical Guidance
(Second Edition)" EPA/625/5-87/019,
January 1988.
8.3 "Application of Radon Reduction
Methods," EPA/625/5-88/024, August 1988.
8.4 "Indoor Radon and Radon Decay
Product Measurement Device Protocols,"
EPA 402-R-92-004, July, 1992.
8.5 "Protocols for Radon and Radon
Decay Product Measurements in Homes,"
EPA 402-R-92-003, June, 1993.
8.6 "A Citizen's Guide To Radon
(Second Edition)" EPA 402-K92-001, May
1992.
8.7 "Consumer's Guide to Radon Reduc-
tion," EPA, 402-K92-003, August, 1992.
8.8 "Home Buyer's and Seller's Guide to
Radon," EPA 402-R-93-003, March, 1993.
8.9 "ASHRAE Standard 62-1989,"
Appendix B, Positive Combustion Air
Supply.
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8.10 "National Gas Code," Appendix H
(p.2223.1-98), 1988, Recommended
Procedure for Safety Inspection of an
Existing Appliance Installation.
8.11 "Chimney Safety Tests User's
Manual," Second Edition, January 12, 1988,
Scanada Shelter Consortium Inc., for
Canada Mortgage and Housing Corp.
8.12 OSHA "Safety and Health Regula-
tions for Construction, Ionizing Radia-
tion," 29 CFR 1926.53.
8.13 OSHA "Occupational Safety and
Health Regulations, Ionizing Radiation,"
29 CFR 1910.96.
8.14 NIOSH" Guide to Industrial Respira-
tory Protection," DHHS (NIOSH) Publica-
tion No. 87-116, September, 1987.
8.15 NCRP "Measurement of Radon and
Radon Decay Daughters in Air," NCRP
Report No. 97, Nov 1988.
8.16 EPA "Handbook, Sub-Slab
Depressurization for Low-Permeability Fill
Material," EPA/625/6-91/029, July 1991.
8.17 "Radon Reduction Techniques for
Existing Detached Houses, Technical
Guidance (Third Edition) for Active Soil
Depressurization Systems," EPA/625/R-93-
011, October, 1993.
9.0 DESCRIPTION OF TERMS
For this document, certain terms are defined
in this section. Terms not defined herein
should have their ordinary meaning within
the context of their use. Ordinary meaning
is as defined in "Webster's Ninth New
Collegiate Dictionary."
9.1 Backdrafting: A condition where the
normal movement of combustion products
up a flue, resulting from the buoyant forces
on the hot gases, is reversed, so that the
combustion products can enter the house.
Backdrafting of combustion appliances (such
as fireplaces and furnaces) can occur when
depressurization in the house overwhelms
the buoyant force on the hot gases.
Backdrafting can also be caused by high air
pressures or blockage at the chimney or flue
termination.
9.2 Backer Rod: A semi-rigid foam
material resembling a rope of various
diameters. Used to fill around pipes, etc. to
assist in making a sealed penetration. For
example, where a pipe is inserted through a
concrete slab, a length of backer rod is
jammed into the opening around the pipe.
Caulking is then applied to the space above
the backer rod and between the outside of
the pipe and the slab opening. The purpose
of the backer rod is to hold the semi-fluid
caulk in place until it sets or hardens.
9.3 Block Wall Depressurization: A
radon mitigation technique that depressurizes
the void network within a block wall
foundation by drawing air from inside the
wall and venting it to the outside.
9.4 Perimeter Channel Drain: A means
for collecting water in a basement by means
of a large gap or channel between the
concrete floor and the wall. Collected water
may flow to aggregate beneath the slot
("French Drain") or to a sump where it can
be drained or pumped away.
9.5 Certified: A rating applied by some
jurisdictions to individuals or firms that are
qualified and authorized to provide radon
testing or mitigation services within the area
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of their jurisdiction.
9.6 Client: The person, persons, or
company that contracts with a radon
mitigation contractor to install a radon
reduction system in a building.
9.7 Combination Foundations: Buildings
constructed with more than one foundation
type, e.g., basement/crawlspace
basement/slab-on-grade.
or
9.8 Communication Test: A diagnostic
test designed to qualitatively measure the
ability of a suction field and air flow to
extend through the material beneath a
concrete slab floor and thus evaluate the
potential effectiveness of a sub-slab
depressurization system. This qualitative
test is commonly conducted by applying
suction on a centrally located hole drilled
through the concrete slab and simultaneously
observing the movement of smoke
downward into small holes drilled in the
slab at locations separated from the central
suction hole. (See also paragraph 9.16,
Pressure Field Extension.)
9.9 Contractor: An individual listed in the
RCP program, or certified by a state which
requires adherence to the RMS.
9.10 Crawlspace Depressurization: A
radon control technique designed to achieve
lower air pressure in the crawlspace relative
to indoor air pressure by use of a fan-
powered vent drawing air from within the
crawlspace. (See also paragraph 9.14,
Mechanically Ventilated Crawlspace
System.)
9.11 Diagnostic Tests: Procedures used to
identify or characterize conditions within
buildings that may contribute to radon entry
or elevated radon levels or may provide
information regarding the performance of a
mitigation system.
9.12 Drain Tile Loop: A continuous
length of drain tile or perforated pipe
extending around all or part of the internal
or external perimeter of a basement or
crawlspace footing.
9.13 Mitigation System: Any system or
steps designed to reduce radon concen-
trations in the indoor air of a building.
9.14 Mechanically Ventilated Crawlspace
System: A radon control technique
designed to increase ventilation within a
crawlspace, achieve higher air pressure in
the crawlspace relative to air pressure in the
soil beneath the crawlspace, or achieve
lower air pressure in the crawlspace relative
to air pressure in the living spaces, by use
of a fan. (See also paragraph 9.10,
Crawlspace Depressurization.)
9.15 pCi/L: The abbreviation for
picocuries per liter which is a unit of
measure for the amount of radioactivity in a
liter of air. The prefix "pico" means a
multiplication factor of 1 trillionth.
A Curie is a commonly used measurement
of radioactivity.
9.16 Pressure Field Extension: The
distance that a pressure change is induced in
the sub-slab area, measured from a single or
multiple suction points. (See also paragraph
9.8, Communication Test.)
9.17 Radon: A naturally occurring
radioactive element (Rn-222) which exists as
a gas and is measured in picocuries per liter
(pCi/L).
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9.18 Radon Decay Products: The four
short-lived radioactive elements (Po-218,
Pb-214, Bi-214, Po-214) which exist as
solids and immediately follow Rn-222 in the
decay chain. They are measured in working
levels (WL).
9.19 Re-Entrainment: The unintended re-
entry into a building of radon that is being
exhausted from the vent of a radon
mitigation system.
9.20 Soil Gas: The gas mixture present in
soil which may contain radon.
9.21 Soil-Gas Retarder: A continuous
membrane or other comparable material
used to retard the flow of soil gases into a
building.
9.22 Stack Effect: The overall upward
movement of air inside a building that
results from heated air rising and escaping
through openings in the building envelope,
thus causing indoor air pressure in the lower
portions of a building to be lower than the
pressure in the soil beneath or surrounding
the building foundation.
9.23 Sub-Membrane Depressurization: A
radon control technique designed to achieve
lower air pressure in the space under a soil-
gas-retarder membrane laid on the crawl-
space floor, relative to air pressure in the
crawlspace, by use of a fan-powered vent
drawing air from beneath the membrane.
9.24 Sub-Slab Depressurization (Active):
A radon control technique designed to
achieve lower sub-slab air pressure relative
to indoor air pressure by use of a fan-
powered vent drawing air from beneath the
concrete slab.
9.25 Sub-Slab Depressurization (Passive):
A radon control technique designed to
achieve lower sub-slab air pressure relative
to indoor air pressure by use of a vent pipe
(without a fan) routed through the condi-
tioned space of a building and connecting
the sub-slab area to the outdoor air. This
system relies primarily on the convective
flow of warmed air upward in the vent to
draw air from beneath the concrete slab.
9.26 Working Level (WL): A unit of
radon decay product exposure rate.
Numerically, any combination of short-lived
radon decay products in one liter of air that
will result in the ultimate emission of
130,000 MeV of potential alpha energy.
This number was chosen because it is
approximately the total alpha energy
released from the short-lived decay products
in equilibrium with 100 pCi of Rn-222 per
liter of air. (See also the referenced
document in paragraph 8.15.)
9.27 Working Level Month (WLM): A
unit of exposure used to express the
accumulated human exposure to radon decay
products. It is calculated by multiplying the
average working level to which a person has
been exposed by the number of hours
exposed and dividing the product by 170.
10.0 GENERAL PRACTICES
The following general practices are required
for all contacts between radon mitigation
contractors and clients.
10.1 In the initial contact with a client,
the contractor shall review any available
results from previous radon tests to assist in
developing an appropriate mitigation
strategy.
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10.2 Based on guidance contained in "A
Citizen's Guide to Radon (Second Edition),"
(paragraph 8.6) or subsequent revisions of
that document, the contractor shall refer the
client to the discussions of interpreting
indoor radon test results and the health risk
associated with the radon level found in the
building. The "Consumer's Guide to Radon
Reduction," (paragraph 8.7) is an appro-
priate reference for providing advice on
actions to take to reduce indoor radon
levels. Similar documents developed by
states and mandated for dissemination by
state regulations may also be used as
references.
10.3 When delays in the installation of a
permanent radon control system are
unavoidable due to building conditions or
construction activities, and a temporary
system is installed, the contractor shall
inform the client about the temporary nature
of the system. A label that is readable from
at least three feet shall be placed on the
system. The label shall include a statement
that the system is temporary and that it will
be replaced with a permanent system within
30 days. The label shall also include the
date of installation, and the contractor's
name, phone number, and RCP
Identification Number. (EXCEPTION: The
30 day limit on use of a temporary
mitigation system may be extended in cases
where a major renovation or change in
building use necessitates a delay in
installation of a permanent mitigation system
that is optimized to the new building
configuration or use. The appropriate state
or local building official or radon program
official should be notified when this
exception is being applied.)
bonding chemicals containing volatile
solvents, prior to starting work the
contractor shall inform the client of the need
to ventilate work areas during and after the
use of such materials. Ventilation shall be
provided as recommended by the
manufacturer of the material.
11.0 BUILDING INVESTIGATION
11.1 The contractor shall conduct a
thorough visual inspection of the building
prior to initiating any radon mitigation
work. The inspection is intended to identify
any specific building characteristics and
configurations (e.g., large cracks in slabs,
exposed earth in crawlspaces, open
stairways to basements) and operational
conditions (e.g., continuously running
HVAC systems or operational windows) that
may affect the design, installation, and
effectiveness of radon mitigation systems.
As part of this inspection, clients should be
asked to provide any available information
on the building (e.g., construction
specifications, pictures, drawings, etc.) that
might be of value in determining the radon
mitigation strategy.
11.2 To facilitate selection of the most
effective radon control system and avoid the
costs of installing systems that subsequently
prove to be ineffective, it is recommended
that the contractor conduct diagnostic tests
to assist in identifying and verifying sus-
pected radon sources and entry points.
Radon grab sampling, Continuous radon
monitoring, and use of chemical smoke
sticks are examples of the type of diagnostic
testing commonly used. (See paragraph
11.4).
10.4 When the selected mitigation tech-
nique requires use of sealants, caulks, or
11.3 It is recommended that during the
building investigation, contractors routinely
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perform diagnostic tests to evaluate the
existence of, or the potential for, back-
drafting of natural draft combustion appli-
ances. Published procedures for conducting
backdrafting tests are covered in the
Reference Documents listed in Paragraphs
8.9, 8.10, and 8.11. The following
checklist has been extracted from material in
these references and may be used to test for
existing or potential backdrafting conditions:
(1) Close all windows and doors, both
external and internal.
(2) Open all HVAC supply and return
air duct vents/registers.
(3) Close fireplace and wood stove
dampers.
(4) Turn on all exhaust and air
distribution fans and combustion
appliances EXCEPT the appliance
being tested for backdrafting.
(5) Wait 5 minutes.
(6) Test to determine the indoor-outdoor
pressure differential in the room
where the appliance being tested is
located. If the pressure differential
is a negative 5 Pascals or more,
assume that a potential for
backdrafting exists.
(7) To begin a test for actual spillage of
flue gases, turn on the appliance
being tested. (If the appliance is a
forced air furnace, ensure that the
blower starts to run before
proceeding.)
(8) Wait 5 minutes.
(9) Using either a smoke tube or a
carbon dioxide gas analyzer, check
for flue gas spillage near the vent
hood.
(10) Repeat steps (4) through (9) for each
natural draft combustion appliance
being tested for backdrafting.
Seasonal and extreme weather
conditions should be considered
when evaluating pressure
differentials and the potential for
backdrafting.
If spillage is confirmed from any natural
draft combustion appliance, clients shall be
advised of the backdrafting condition and
that active (fan-powered) radon mitigation
systems cannot be installed until the
condition has been corrected. Contractors
should advise the client to contact an HVAC
contractor if correcting an existing or
potential backdrafting condition is necessary.
(See paragraph 17.3 for post-mitigation
backdrafting testing.)
11.4 If installation of a sub-slab
depressurization system is contemplated and
characteristics of the sub-slab material are
unknown, a communication test, as defined
in paragraph 9.8 is recommended.
11.5 As part of the building investigation,
a floor-plan sketch shall be developed (if not
already in existence and readily available)
that includes illustrations of the building
foundation (slab-on-grade, basement or
crawlspace area.) The sketch should include
the location of load-bearing walls, drain
fixtures and HVAC systems. It should be
annotated to include suspected or confirmed
radon entry points, results of any diagnostic
testing, the anticipated layout of any radon
mitigation system piping, and the anticipated
locations of any vent fan and system
warning devices for the envisioned
mitigation systems. The sketch shall be
finalized during installation and shall be
included in the documentation. (See
paragraph 18.2 and Appendix A.)
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12.0 WORKER HEALTH AND SAFETY
12.1 Contractors shall comply with all
OSHA, state and local standards or
regulations relating to worker safety and
occupational radon exposure. Applicable
references in the Code of Federal
Regulations and NIOSH publications are
listed in paragraphs 8.12, 8.13, and 8.14.
12.2 In addition to the OSHA and NIOSH
standards, the following requirements that
are specifically or uniquely applicable for
the safety and protection of radon mitigation
workers shall be met:
12.2.1 The contractor shall advise
workers of the hazards of exposure to radon
and the need to apply protective measures
when working in areas of elevated radon
concentrations.
12.2.2 The contractor shall have a
worker protection plan on file that is
available to all employees and is approved
by any state or local regulating agencies that
require such a plan. Exception: A worker
protection plan is not required for a
contractor who is a sole proprietor unless
required by state or local regulations.
12.2.3 The contractor shall ensure
that appropriate safety equipment such as
hard hats, face shields, ear plugs, steel-toe
boots and protective gloves are available on
the job site during cutting, drilling,
grinding, polishing, demolishing or other
activity associated with radon mitigation
projects.
12.2.4 All electrical equipment used
during radon mitigation projects shall be
properly grounded. Circuits used as a
power source should be protected by
Ground-fault Circuit Interrupters (GFCI).
12.2.5 When work is required at
elevations above the ground or floor, the
contractor shall ensure that ladders or
scaffolding are safely installed and operated.
12.2.6 Work areas shall be
ventilated to reduce worker exposure to
radon decay products, dust, or other
airborne pollutants. In work areas where
ventilation is impractical or where
ventilation cannot reduce radon levels to less
than 0.3 WL (based on a short term
diagnostic test, e.g., grab sample), the
contractor shall ensure that respiratory
protection conforms with the requirements in
the NIOSH Guide to Industrial Respiratory
Protection. (See paragraph 8.14.) (Note: If
unable to make working level measure-
ments, a radon level of 30 pCi/L shall be
used.)
12.2.7 Where combustible materials
exist in the specific area of the building
where radon mitigation work is to be
conducted and the contractor is creating any
temperatures high enough to induce a flame,
the contractor shall ensure that fire
extinguishers suitable for type A, B, and C
fires are available in the immediate work
area.
12.2.8 Pending development of an
approved personal radon exposure device
and a protocol for its use, contractors shall
record employee exposure to radon at each
work site, based on: (1) the highest pre-
mitigation indoor radon or working level
measurement available, and (2) the time
employees are exposed (without respirator
protection) at that level (See paragraph
12.2.6.) (Note: This approach is not
intended to preclude the alternative use of
on-site radon or radon decay product
measurements to determine exact exposure.)
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Consistent with OSHA Permissible Exposure
Limits, contractors shall ensure that
employees are exposed to no more than 4
working level months (WLM) over a 12
month period. (An equilibrium ratio of 50
percent shall be used to convert radon
exposure to WLM.)
12.2.9 In any planned work area
where it is suspected that friable asbestos
may exist and be disturbed, radon mitigation
work shall not be conducted until a
determination is made by a properly trained
or accredited person that such work will be
undertaken in a manner which complies with
applicable asbestos regulations.
12.2.10 When mitigation work
requires the use of sealants, adhesives,
paints, or other substances that may be
hazardous to health, contractors shall
provide employees with the applicable
Material Safety Data Sheets (MSDS) and
explain the required safety procedures.
13.0 SYSTEMS DESIGN
13.1 All radon mitigation systems shall be
designed and installed as permanent, integral
additions to the building, except where a
temporary system has been installed in
accordance with paragraph 10.3.
13.2 AH radon mitigation systems shall be
designed to avoid the creation of other
health, safety, or environmental hazards to
building occupants, such as backdrafting of
natural draft combustion appliances.
13.3 All radon mitigation systems shall be
designed to maximize radon reduction and in
consideration of the need to minimize excess
energy usage, to avoid compromising
moisture and temperature controls and other
comfort features, and to minimize noise.
13.4 All radon mitigation systems and
their components shall be designed to
comply with the laws, ordinances, codes,
and regulations of relevant jurisdictional
authorities, including applicable mechanical,
electrical, building, plumbing, energy, and
fire prevention codes.
14.0 SYSTEMS INSTALLATION
14.1 General Requirements
14.1.1 All components of radon
mitigation systems installed in compliance
with provisions of the RMS shall also be in
compliance with the applicable mechanical,
electrical, building, plumbing, energy and
fire prevention codes, standards, and
regulations of the local jurisdiction.
14.1.2 The contractor shall obtain
all required licenses and permits, and
display them in the work areas as required
by local ordinances.
14.1.3 Where portions of structural
framing material must be removed to
accommodate radon vent pipes, material
removed shall be no greater than that
permitted for plumbing installations by
applicable building or plumbing codes.
14.1.4 Where installation of a radon
mitigation system requires pipes or ducts to
penetrate a firewall or other fire resistance
rated wall or floor, penetrations shall be
protected in accordance with applicable
building, mechanical, fire, and electrical
codes.
14.1.5 When installing radon
mitigation systems that use sump pits as the
suction point for active soil depressurization,
if sump pumps are needed, it is
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recommended that submersible sump pumps
be used. (See paragraphs 14.5.1, 14.7.4,
15.7, and 15.8.)
14.2 Radon Vent Pipe Installation
Requirements
14.2.1 All joints and connections in
radon mitigation systems using plastic vent
pipes shall be permanently sealed with
adhesives as specified by the manufacturer
of the pipe material used. (See paragraph
14.3.7 for exception when installing fans,
and paragraph 14.2.7 for exception when
installing vent pipes in sumps.) Joints or
connections in other vent pipe materials
shall be made air tight.
14.2.2 Attic and external piping
runs in areas subject to sub-freezing
conditions should be protected to avoid the
risk of vent pipe freeze-up.
14.2.3 Radon vent pipes shall be
fastened to the structure of the building with
hangers, strapping, or other supports that
will adequately secure the vent material.
Existing plumbing pipes, ducts, or
mechanical equipment shall not be used to
support or secure a radon vent pipe.
14.2.4 Supports for radon vent pipes
shall be installed at least every 6 feet on
horizontal runs. Vertical runs shall be
secured either above or below the points of
penetration through floors, ceilings, and
roofs, or at least every 8 feet on runs that
do not penetrate floors, ceilings, or roofs.
14.2.5 To prevent blockage of air
flow into the bottom of radon vent pipes,
these pipes shall be supported or secured in
a permanent manner that prevents their
downward movement to the bottom of
suction pits or sump pits, or into the soil
beneath an aggregate layer under a slab.
14.2.6 Radon vent pipes shall be
installed in a configuration that ensures that
any rain water or condensation within the
pipes drains downward into the ground
beneath the slab or soil-gas retarder
membrane.
14.2.7 Radon vent pipes shall not
block access to any areas requiring
maintenance or inspection. Radon vents
shall not be installed in front of or interfere
with any light, opening, door, window or
equipment access area required by code. If
radon vent pipes are installed in sump pits,
the system shall be designed with removable
or flexible couplings to facilitate removal of
the sump pit cover for sump pump
maintenance.
14.2.8 To prevent re-entrainment of
radon, the point of discharge from vents of
fan-powered soil depressurization and block
wall depressurization systems shall meet all
of the following requirements: (1) be above
the eave of the roof, (2) be ten feet or more
above ground level, (3) be ten feet or more
from any window, door, or other opening
into conditioned spaces of the structure that
is less than two feet below the exhaust
point, and (4) be ten feet or more from any
opening into an adjacent building. The total
required distance (ten feet) from the point of
discharge to openings in the structure may
be measured either directly between the two
points or be the sum of measurements made
around intervening obstacles. Whenever
possible, the exhaust point should be
positioned above the highest eave of the
building and as close to the roof ridge line
as possible.
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14.2.9 When a radon mitigation
system is designed to draw soil gas from a
perimeter drain tile loop (internal or
external) that discharges water through a
drain line to daylight or a soakaway, a one-
way flow valve, water trap, or other control
device should be installed in or on the
discharge line to prevent outside air from
entering the system while allowing water to
flow out of the system.
14.3 Radon Vent Fan Installation
Requirements
14.3.1 Vent fans used in radon
mitigation systems shall be designed or
otherwise sealed to reduce the potential for
leakage of soil gas from the fan housing.
14.3.2 Radon vent fans shall be
sized to provide the pressure difference and
air flow characteristics necessary to achieve
the radon reduction goals established for the
specific mitigation project. Guidelines for
sizing vent fans and piping can be found in
the references cited in paragraphs 8.1,8.16,
and 8.17.
14.3.3 Radon vent fans used in
active soil depressurization or block wall
depressurization systems shall not be
installed below ground nor in the
conditioned (heated/cooled) space of a
building, nor in any basement, crawlspace,
or other interior location directly beneath the
conditioned spaces of a building.
Acceptable locations for radon vent fans
include attics not suitable for occupancy
(including attics over living spaces and
garages), garages that are not beneath
conditioned spaces, or on the exterior of the
building.
14.3.4 Radon vent fans shall be
installed in a configuration that avoids
condensation buildup .in the fan housing.
Whenever possible, fans should be installed
in vertical runs of the vent pipe.
14.3.5 Radon vent fans mounted on
the exterior of buildings shall be rated for
outdoor use or installed in a water tight
protective housing.
14.3.6 Radon vent fans shall be
mounted and secured in a manner that
minimizes transfer of vibration to the
structural framing of the building.
14.3.7 To facilitate maintenance and
future replacement, radon vent fans shall be
installed in the vent pipe using removable
couplings or flexible connections that can be
tightly secured to both the fan and the vent
pipe.
14.3.8 The intakes of fans used in
crawlspace pressurization, or in pressurizing
the building itself, shall be screened or
filtered to prevent ingestion of debris or
personal injury. Screens or filters shall be
removable to permit cleaning or replacement
and building owners shall be informed of the
need to periodically replace or clean such
screens and filters. This information shall
also be included in the documentation. (See
paragraph 18.5)
14.4 Suction Pit Requirement for Sub-
Slab Depressurization (SSD) Systems
14.4.1 To provide optimum pressure
field extension of the sub-slab
communication zone, adequate material shall
be excavated from the area immediately
below the slab penetration point of SSD
system vent pipes.
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14.5 Sealing Requirements
14.5.1 Sump pits that permit entry
of soil-gas or that would allow conditioned
air to be drawn into a sub-slab
depressurization system shall be covered and
sealed. The covers on sumps that
previously provided protection or relief from
surface water collection shall be fitted with
a water or mechanically trapped drain.
Water traps should be fitted with an
automatic supply of priming water. (See
paragraph 15.7 for details on sump cover
and sealing materials.)
14.5.2 Openings around radon vent
pipe penetrations of the slab, the foundation
walls, or the crawlspace soil-gas retarder
membrane shall be cleaned, prepared, and
sealed in a permanent, air-tight manner
using compatible caulks or other sealant
materials. (See paragraph 15.5.) Openings
around other utility penetrations of the slab,
walls, or soil-gas retarder shall also be
sealed.
14.5.3 Where a Block Wall
Depressurization (BWD) system is used to
mitigate radon, openings in the tops of such
walls and all accessible openings or cracks
in the interior surfaces of the walls shall be
closed and sealed with polyurethane or
equivalent caulks, expandable foams, or
other fillers and sealants. (See paragraphs
15.5 and 15.6.) Openings or cracks that are
determined to be inaccessible or beyond the
ability of the contractor to seal shall be
disclosed to the client and included in the
documentation.
14.5.4 Openings, perimeter channel
drains, or cracks that exist where the slab
meets the foundation wall (floor-wall joint),
shall be sealed with urethane caulk or
equivalent material. When the opening or
channel is greater than 1/2 inch in width, a
foam backer rod or other comparable filler
material shall be inserted in the channel
before application of the sealant. This
sealing technique shall be done in a manner
that retains the channel feature as a water
control system. Other openings or cracks in
slabs or at expansion or control joints should
also be sealed. Openings or cracks that are
determined to be inaccessible or beyond the
ability.of the contractor to seal shall be
disclosed to the client and included in the
documentation.
14.5.5 When installing baseboard-
type suction systems, all seams and joints in
the baseboard material shall be joined and
sealed using materials recommended by the
manufacturer of the baseboard system.
Baseboards shall be secured to walls and
floors with adhesives designed and
recommended for such installations. If a
baseboard system is installed on a block wall
foundation, the tops of the blockwall shall
be closed and sealed as prescribed in
paragraph 14.5.3.
14.5.6 Any seams in soil-gas
retarder membranes used in crawlspaces for
sub-membrane depressurization systems
shall be overlapped at least 12 inches and
should be sealed. To enhance the
effectiveness of sub-membrane
depressurization systems, the membrane
should also be sealed around interior piers
and to the inside of exterior walls.
14.5.7 In combination
basement/crawlspace foundations, where the
crawlspace has been confirmed as a source
of radon entry, access doors and other
openings between the basement and the
adjacent crawlspace shall be closed and
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sealed. Access doors required by code shall
be fitted with air tight gaskets and a means
of positive closure, but shall not be
permanently sealed. In cases where both the
basement and the adjacent crawlspace areas
are being mitigated with active SSD and
SMD systems, sealing of the openings
between those areas is not required.
14.5.8 When crawlspace
depressurization is used for radon
mitigation, openings and cracks in floors
above the crawl-space which would permit
conditioned air to pass out of the living
spaces of the building, shall be identified,
closed, and sealed. Sealing of openings
around hydronic heat or steam pipe
penetrations shall be done using non-
combustible materials. Openings or cracks
that are determined to be inaccessible or
beyond the ability of the contractor to seal
shall be disclosed to the client and included
in the documentation.
14.6 Electrical Requirements
14.6.1 Wiring for all active radon
mitigation systems shall conform to
provisions of the National Electric Code and
any additional local regulations.
14.6.2 Wiring may not be located in
or chased through the mitigation installation
ducting or any other heating or cooling
ductwork.
14.6.3 Any plugged cord used to
supply power to a radon vent fan shall be no
more than 6 feet in length.
14.6.4 No plugged cord may
penetrate a wall or be concealed within a
wall.
14.6.5 Radon mitigation fans
installed on the exterior of buildings shall be
hard-wired into an electrical circuit.
Plugged fans shall not be used outdoors.
14.6.6 If the rated electricity
requirements of a radon mitigation system
fan exceeds 50 percent of the circuit
capacity into which it will be connected, or
if the total connected load on the circuit
(including the radon vent fan) exceeds 80
percent of the circuit's rated capacity, a
separate, dedicated circuit shall be installed
to power the fan.
14.6.7 An electrical disconnect
switch or circuit breaker shall be installed in
radon mitigation system fan circuits to
permit deactivation of the fan for
maintenance or repair by the building owner
or servicing contractor (Disconnect switches
are not required with plugged fans).
14.7 Drain Installation Requirements
14.7.1 If drains discharge directly
into the soil beneath the slab or through
solid pipe to a soakaway, the contractor
should install a drain that meets the
requirements in paragraph 14.5.1.
14.7.2 If condensate drains from air
conditioning units terminate beneath the
floor slab, the contractor shall install a trap
in the drain that provides a minimum 6-inch
standing water seal depth, reroute the drain
directly into a trapped floor drain, or
reconnect the drain to a condensate pump.
14.7.3 Perimeter (channel or
French) drains should be sealed with backer
rods and urethane or comparable sealants in
a manner that will retain the channel feature
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as a water control system. (See paragraph
14.5.4.)
14.7.4 When a sump pit is the only
system in a basement for protection or relief
from excess surface water and a cover is
installed on the sump for radon control, the
cover shall be recessed and fitted with a
trapped drain meeting the requirements of
paragraph 14.5.1.
14.8 HVAC Installation Requirements
14.8.1 Modifications to an existing
HVAC system, which are proposed to
mitigate elevated levels of radon, should be
reviewed and approved by the original
designer of the system (when possible) or by
a licensed mechanical contractor.
14.8,2 Foundation vents, installed
specifically to reduce indoor radon levels by
increasing the natural ventilation of a
crawlspace, shall be non-closeable. In areas
subject to sub-freezing conditions, the
existing location of water supply and
distribution pipes in the crawlspace, and the
need to insulate or apply heat tape to those
pipes, should be considered when selecting
locations for installing foundation vents.
14.8.3 Heat Recovery Ventilation
(HRV) systems shall not be installed in
rooms that contain friable asbestos.
14.8.4 In HRV installations, supply
and exhaust ports in the interior shall be
located a minimum of 12 feet apart. The
exterior supply and exhaust ports shall be
positioned to avoid blockage by snow or
leaves and be a minimum of 10 feet apart.
14.8.5 Contractors installing HRV
systems shall verify that the incoming and
outgoing airflow is balanced to ensure that
the system does not create a negative
pressure within the building. Contractors
shall inform building owners that periodic
filter replacement and inlet grill cleaning are
necessary to maintain a balanced airflow.
This information shall also be included in
the documentation.
14.8.6 Both internal and external
intake and exhaust vents in HRV systems
shall be covered with wire mesh or
screening to prevent entry of animals or
debris or injury to occupants.
15.0 MATERIALS
15.1 All mitigation system electrical
components shall be U.L. listed or of
equivalent specifications.
15.2 As a minimum, all plastic vent pipes
in mitigation systems shall be made of
Schedule 20 PVC, ABS or equivalent piping
material. Schedule 40 piping or its
equivalent should be used in garages and in
other internal and external locations subject
to weathering or physical damage.
15.3 Vent pipe fittings in a mitigation
system shall be of the same material as the
vent pipes. (See paragraph 14.3.7 for
exception when installing vent fans, and
paragraph 14.2.7 for exception when install-
ing radon vent pipes in sump pit covers.
15.4 Cleaning solvents and adhesives used
to join plastic pipes and fittings shall be as
recommended by manufacturers for use with
the type of pipe material used in the
mitigation system.
15.5 When sealing cracks in slabs and
other small openings around penetrations of
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the slab and foundation walls, caulks and
sealants designed for such application shall
be used. Urethane sealants are
recommended because of their durability.
15.6 When sealing holes for plumbing
rough-in or other large openings in slabs and
foundation walls that are below the ground
surface, non-shrink mortar, grouts,
expanding foam, or similar materials
designed for such application shall be used.
15.7 Sump pit covers shall be made of
durable plastic or other rigid material and
designed to permit air-tight sealing. To
permit easy removal for sump pump
servicing, the cover shall be sealed using
silicone or other non-permanent type
caulking materials or an air-tight gasket.
15.8 Penetrations of sump covers to
accommodate electrical wiring, water
ejection pipes, or radon vent pipes shall be
designed to permit air-tight sealing around
penetrations, using caulk or grommets.
Sump covers that permit observation of
conditions in the sump pit are
recommended.
15.9 Plastic sheeting installed in
crawlspaces as soil-gas retarders shall be a
minimum of 6 mil (3 mil cross-laminated)
polyethylene or equivalent flexible material.
Heavier gauge sheeting should be used when
crawlspaces are used for storage, or frequent
entry is required for maintenance of utilities.
15.10 Any wood used in attaching soil-gas
retarder membranes to crawlspace walls or
piers shall be pressure treated or naturally
resistant to decay and termites.
16.0 MONITORS AND LABELING
16.1 All active soil depressurization and
block wall depressurization radon mitigation
systems shall include a mechanism to
monitor system performance and warn of
system failure. The mechanism shall be
simple to read or interpret and be located
where it is easily seen or heard by building
occupants and protected from damage or
destruction.
16.2 Electrical radon mitigation system
monitors (whether visual or audible) shall be
installed on non-switched circuits and be
designed to reset automatically when power
is restored after service or power supply
failure. Battery operated monitoring devices
shall not be used unless they are equipped
with a low-power warning feature.
16.3 Mechanical radon mitigation system
monitors, such as manometer type pressure
gauges, shall be clearly marked to indicate
the range or zone of pressure readings that
existed when the system was initially
activated.
16.4 A system description label shall be
placed on the mitigation system, the electric
service entrance panel, or other prominent
location. This label shall be legible from a
distance of at least three feet and include the
following information: "Radon Reduction
System," the installer's name, phone
number, and RCP Identification Number,
the date of installation, and an advisory that
the building should be tested for radon at
least every two years or as required or
recommended by state or local agencies. In
addition, all exposed and visible interior
radon mitigation system vent pipe sections
shall be identified with at least one label on
each floor level. The label shall read,
"Radon Reduction System."
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16.5 The circuit breakers controlling the
circuits on which the radon vent fan and
system failure warning devices operate shall
be labeled "Radon System."
17.0 POST-MITIGATION TESTING
17.1 After installation of an active radon
control system (e.g., SSD), the contractor
shall re-examine and verify the integrity of
the fan mounting seals and all joints in the
interior vent piping.
17.2 After installation of any active radon
mitigation system, the contractor shall
measure suctions or flows in system piping
or ducting to assure that the system is
operating as designed. (Note: When SSD
systems are installed and activated, a test of
pressure field extension is a good practice,
particularly when there is uncertainty
regarding the permeability of materials
under all parts of the slab.)
17.3 Immediately after installation and
activation of any active (fan-powered) sub-
slab depressurization or block wall
depressurization system in buildings
containing natural draft combustion
appliances, the building shall be tested for
backdrafting of those appliances. Any
backdrafting condition that results from
installation of the radon mitigation system
shall be corrected before the system is
placed in operation. (Procedures and a
checklist for conducting backdrafting tests
are covered in the reference documents
listed in paragraphs 8.9, 8.10, and 8.11, and
in paragraph 11.3.)
17.4 Upon completion of radon mitigation
work, a test of mitigation system
effectiveness shall be conducted using an
RMP listed test device and in accordance
with EPA testing protocols or state
requirements. This test should be conducted
no sooner than 24 hours nor later than 30
days following completion and activation of
the mitigation system(s). This test may be
conducted by the contractor, by the client,
or by a third party testing firm. If this test
is conducted by the mitigation contractor,
and the test results are accepted by the client
as satisfactory evidence of system
effectiveness, further post-mitigation testing
is not required. However, to avoid the
appearance of conflict of interest, the
contractor shall recommend to the client that
a mitigation system effectiveness test be
conducted by an independent RMP listed or
state certified testing firm or by the client.
The contractor should request a copy of the
report of any post-mitigation testing
conducted by the client or by an independent
testing firm.
17.5 To ensure continued effectiveness of
the radon mitigation system(s) installed, the
contractor shall advise the client to retest the
building at least every two years or as
required or recommended by state or local
authority. Retesting is also recommended if
the building undergoes significant alteration.
AND
18.0 CONTRACTS
DOCUMENTATION
18.1 EPA recommends that contractors
provide the following written information to
clients prior to initiation of work:
(1) The contractor's RCP Program
identification number.
(2) A statement that describes the
planned scope of the work and that
includes an estimate of the time
needed to complete the work.
(3) A statement describing any known
hazards associated with chemicals
used in or as part of the installation.
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(4) A statement indicating compliance
with and implementation of all EPA
standards and those of other agencies
having jurisdiction (e.g., code
requirements).
(5) A statement describing any system
maintenance that the building owner
would be required to perform.
(6) An estimate of the installation cost
and annual operating costs of the
system.
(7) The conditions of'any warranty or
guarantee.
18.2 EPA recommends that RCP listed
contractors keep records of all radon
mitigation work performed and maintain
those records for 3 years or for the period
of any warranty or guarantee, whichever is
longer. These records should include:
(1) The Building Investigation Summary
and floor plan sketch. (See Appendix
A.)
(2) Pre- and post-mitigation radon test
data.
(3) Pre- and post-mitigation diagnostic
test data.
(4) Copies of contracts and warranties.
(5) A narrative or pictorial description
of mitigation system(s) installed.
18.2.1 Appendix A contains a
suggested standard format for compiling
mitigation project records.
18.3 Other records or bookkeeping
required by local, state, or Federal statutes
and regulations shall be maintained for the
period(s) prescribed by those requirements.
18.4 EPA recommends that health and
safety records, including worker radon
exposure logs, be maintained for a minimum
of 20 years.
18.5 Upon completion of the mitigation
project, contractors shall provide clients
with an information package that includes:
(1) Any building permits required by
local codes.
(2) Copies of the Building Investigation
Summary and floor plan sketch. (See
Appendix A.)
(3) Pre-and post-mitigation radon test
data.
(4) Copies of contracts and warranties.
(5) A description of the mitigation
system installed and its basic
operating principles.
(6) A description of any deviations from
the RMS or State requirements.
(7) A description of the proper operating
procedures of any mechanical or
electrical systems installed, including
manufacturer's operation and
maintenance instructions and
warranties.
(8) A list of appropriate actions for
clients to take if the system failure
warning device indicates system
degradation or failure.
(9) The name, telephone number, and
RCP Identification Number of the
contractor, and the phone number of
the state radon office.
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APPENDIX A
MITIGATION PROJECT RECORD
RCP Contractor's Name (Sy.'ten Designer)
RCP Identification Number
Contractor's Address
Company Name
Company Address
Client's Name
Client's Address
Type of Building:
D
a
a
Detached Home
Townhome
Other (Describe)
Results
Pre-Mitigation Test
a Homeowner
o RMP Listed Company
n Mitigation Contractor
Post Mitigation Test
n Homeowner
o RMP Listed Company
n Mitigation Contractor
Mitigation Method Used:
a Sub-slab depressurization
o Sub-membrane depressurization
D Block wall depressurization
Test Device(s) Used
o Activated Charcoal
a Electret
n Alpha Track
n Continuous Monitor (Type)
Test Device(s) Used
D Activated Charcoal
a Electret
a Alpha Track
D Continuous Monitor (Type)
n Ventilation
o Pressurization
n Other (Describe)_
Building Investigation Summary and Floor Plan Sketch
Mitigation Standard.)
(See Paragraphs 11.0, 11.5, and 18.2 in the
Use the grid pattern sheet on page 2 of this form to sketch the foundation plan and dimensions of the
building. At the top of page 2 is a list of suggested items for entry on the sketch. If a sub-slab or sub-
membrane depressurization system is installed, the routing of the vent piping in the basement and/or
crawlspace areas should be included, as well as pipe drops into the concrete slab or plastic membrane.
If a fan has been included in the system, describe its location and the location of any monitoring or
system failure warning device(s).
Signature
The contractor performing the Building Investigation, designing the mitigation system, and certifying its
operational performance should sign this Project Record.
Mitigation Contractor
Date
A-l
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APPENDIX A (Continued)
Floor Plan Sketch
(Scale: _ )
Suggested items to include in the sketch:
Foundation dimensions.
Stairways.
Grade-level, walk-out areas from basement.
Heating, Ventilating, Air Conditioning Equipment.
Ductwork.
Ductwork under slabs.
Foundation vents.
Access doors to crawlspaces.
Locations of radon entry.
Open areas to crawlspaces from basements.
Piers and Lolly columns.
Footings located inside the foundation perimeter.
Sump holes/pumps.
Floor drains.
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