15 SEP 93
e. Very High
Greater than 200 pCi/l.
8. DETERMINATION OF RADON POTENT: AR 200-1, Chapter 11 establishes a
program for measuring indoor radon in existing buildings on Army
installations and buildings owned or leased by the Army (CONUS and
OCONUS). The measurements were to be completed by the fourth quarter
of FY 91. Each installation is required to maintain records of the
radon measurements and to make annual reports on all radon mitigation
activities. The pre-mitigation measurements in existing buildings
will be the basis for potential radon levels for new facilities.
Design criteria will be based upon the highest radon measurements in
existing buildings in close proximity to the new facility. Where the
new facility is in a remote location, the highest measurements on the
installation will determine the design criteria. In cases where
existing radon data are not available, soil-based radon and radium
measurement may provide useful information in evaluating radon
potentials. Procedures for using soil gas measurements to estimate
radon potentials are still evolving, contact EPA for the most up-to-
barriers to seal radon entry routes and active sub-slab suction
systems to remove radon gas from the soil under floor slabs and
around below grade walls. The objective of both passive and active
design strategies is to prevent radon entry to interior spaces.
potential radon concentration, are listed in Table 1 by letter codes.
The letter codes are described below and indicated on the details in
(1) Passive Barriers, Letter Code A. Passive barriers are
required for facility priorities 1 through 4 and for all potential
radon concentration levels. Passive barriers include 6 mil
polyethylene sheet in crawl spaces and under floor slabs on grade,
capillary water barrier below floor slabs on grade, dampproofing or
waterproofing and protection board on below grade walls, sealants in
all joints in floor slabs, below grade walls and around all pipe and
conduit penetrations. Provide solid courses in hollow masonry walls
to prevent gas passage through the internal voids. Joint sealants
will be selected and installed according to TM 5-805-6 and CEGS 07920.
Polyethylene sheets will be lapped 12 inches and sealed with adhesives
or pressure sensitive tape and sealed at foundation walls with mastic.
Capillary water barrier will be according to CEGS 02221, dated March
1991, except the last sentence in the Note under Paragraph 3.16 is not
(2) Sub-slab Suction Systems, Letter Codes B, C, and D. Sub-
slab suction systems consist of 4 inch diameter perforated PVC pipe
laid in the capillary water barrier below floor slabs which are used