Section 742.227 Demonstration of Compliance with Soil Gas Remediation Objectives for the Outdoor and Indoor Inhalation Exposure Routes

Section 742.227  Demonstration of Compliance with Soil

Gas Remediation Objectives for the Outdoor and Indoor Inhalation Exposure

Routes

a)         For

purposes of the outdoor inhalation exposure route and the indoor inhalation

exposure route, compliance with soil gas remediation objectives developed under

any tier shall be demonstrated in accordance with this Section by comparing the

contaminant concentrations of discrete samples at each sample point to the

applicable soil gas remediation objective.

b)         This

Section applies to exterior soil gas samples for the outdoor inhalation

exposure route, near-slab soil gas samples collected outside of an existing

building for the indoor inhalation exposure route, and exterior soil gas

samples collected at the footprint of a potential building for the indoor

inhalation exposure route.  Proposals to use sub-slab soil gas data for the

indoor inhalation exposure route shall follow Section 742.935(c).

c)         Sample

points shall be determined by the program under which remediation is performed.

d)         When collecting soil gas

samples:

1)         Use

rigid-wall tubing made of nylon or Teflon

®

or other material

approved by the Agency;

2)         Use

gas-tight, inert containers to hold the sample. For light sensitive or

halogenated volatile chemicals, these containers shall be opaque or

dark-colored;

3)         Purge three volumes

before obtaining each discrete soil gas sample;

4)         Use a

helium tracer or other leak apparatus detection system approved by the Agency;

and

5)         Limit the flow rate to

200 ml/min.

e)         Soil

gas samples shall be analyzed using a National Environmental Laboratory

Accreditation Program (NELAP) certified laboratory.

f)         Soil

gas remediation objectives shall be compared to concentrations of soil gas

collected at a depth at least 3 feet below ground surface and above the

saturated zone.