Owners and operators using vapor monitoring (testing or
monitoring for vapors within the soil gas of the excavation zone) must comply
with the requirements of this section. Except as otherwise provided in WAC
173-360A-0610(3)
or 173-360A-0615(3),
vapor monitoring may be either passive (monitoring for presence of regulated
substance) or active (monitoring for presence of tracer compound).
(1)
Site conditions.
(a) The materials used as backfill must be
sufficiently porous (e.g., gravel, sand, crushed rock) to readily allow
diffusion of vapors from releases into the excavation area.
(b) The stored regulated substance, or a
tracer compound placed in the UST system, must be sufficiently volatile (e.g.,
gasoline) to result in a vapor level that is detectable by the monitoring
devices located in the excavation zone in the event of a release from the UST
system.
(c) The measurement of
vapors by the monitoring device must not be rendered inoperative by the
groundwater, rainfall, or soil moisture or other known interferences so that a
release could go undetected for more than thirty days.
(d) The level of background contamination in
the excavation zone must not interfere with the method used to detect releases
from the UST system.
(2)
Site evaluations. In the
UST excavation zone, the site must be
evaluated to ensure compliance with the requirements in subsection (1) of this
section and to establish the number and positioning of monitoring wells that
will detect releases within the
excavation zone from any portion of the
tank or
piping being monitored that routinely contains product.
(a)
Performance. Site
evaluations must be performed by or under the direct supervision of a service
provider certified in accordance with Part 9 of this chapter.
(b)
Reporting. Site evaluations
must be reported to the
department within thirty days of the installation of
the vapor monitoring system. The report must be submitted with the checklist
required for the installation (WAC
173-360A-0300 (5)(b)). The report must be
completed by the
service provider. The report must identify the
service
provider and their certification type and number.
(3)
Monitoring wells.
(a) Monitoring wells must be clearly marked
and secured to avoid unauthorized access and tampering.
(b) Monitoring wells must be constructed,
maintained, and decommissioned in accordance with chapter
173-160
WAC.
(4)
Vapor
monitors.
(a) Vapor monitors must be
designed and operated to detect any significant increase in concentration above
background of the regulated substance stored in the UST system, a component or
components of that substance, or a tracer compound placed in the UST
system.
(b) Vapor monitors must
also be operated in accordance with the manufacturer's instructions and any
conditions or limitations specified in the certification of the
equipment.
