ETL 1110-3-438
15 SEP 93
required is not quantifiable for inclusion in construction contracts.
Therefore, the installation or user agency will be responsible for
post construction radon measurement and mitigation.
11. POST CONSTRUCTION RADON MITIGATION: When post construction radon
measurements are greater than 4 pci/l, mitigation systems designed
into the facility will be activated incrementally until the radon
level is reduced to less than 4 pci/l. The incremental steps are as
follows:
a.
Activate sub-slab suction systems or power ventilate crawl
spaces.
(1) Install passive vent stack(s) to sub-slab systems for low
and moderate radon levels. If subsequent radon measurements
are greater than 4 pci/ 1, then install exhaust fans for
active vent stack.
(2) Install active vent stack(s) with exhaust fans for high and
very high radon levels.
b.
Increase interior positive air pressure.
c.
Increase the outside-air exchange rate.
12. DESIGN DETAILS:
a.
The following design details are generic in nature to depict
a variety of typical conditions that are adaptable to specific
building designs. Some details shown may not be applicable to every
building; unique conditions are not included. Each detail and/or
portions thereof are identified with letter codes that relate to
Table 1. Additional design guidance may be found in the EPA
publications listed in Paragraphs 3.a.(2), (3), and (4).
b.
Reinforcing for concrete and masonry construction shall be
provided according to specific design requirements and is not
indicated in the following details. Minimum reinforcement to control
shrinkage cracks in concrete slabs on grade will be 6x6-wl.4xwl.4
welded wire fabric.
6
A-8
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