F.2.4 Laboratory conditions

example being that of sampling for PAHs and PCBs. If other COC that require

different sorbent traps are present, additional flux chambers will need to be used.

All samples should be thoroughly homogenized before conducting bulk sediment

analysis and volatile emissions testing.

F.2.4 Laboratory conditions

Testing can be conducted at laboratory ambient temperatures or the

chambers can be placed in temperature controlled water baths to give colder or

warmer sediment temperatures.

F.2.5 Laboratory volatile emissions test procedure

The step-by-step procedure for conducting volatiles emissions testing is

outlined below:

Step 1 Loading flux chamber. Fill flux chamber with a known amount of

sediment to the top of the sediment well (10 cm in height). Ensure that the

sediment surface is as level as possible to promote laminar air flow over the

surface. Seal the chamber using an o-ring and threaded fasteners.

Step 2 Trap attachment. Apply contaminant-specific air sampling tube

to the exit port of the chamber. Sampling tubes can be arranged in a series to

ensure capture of all contaminants if contaminant trap breakthrough is a

possibility. If sediment is extremely wet and trap material retention capacity is

affected by moisture, a moisture retention trap, such as a tube loaded with

Drierite, can be added in-line prior to trap (Figure F-2).

Step 3 Carrier air application. If laboratory "house" air or compressed

air is used, it should be passed through adsorbent traps to remove potential

contaminants prior to use. Attach a flow meter to the air entrance port, followed

by a line to compressed air supply (Figure F-2). If a vacuum pump is used to

pull air over the sediment surface, first attach drier tube (if needed), followed by

absorbent trap, flow meter, and then attach vacuum pump tube to exit side of

flow meter. Pass or pull dry air over the sediment surface at a rate of 1.7 L/min.

(This will ensure maximum contaminant fluxes from the sediment).

Step 4 Sampling. The length of sampling and total sampling period will

be dependent upon contaminant concentrations in the sediment. If

concentrations are relatively low, a longer sampling interval (i.e., 24-hr

continuous sample) may be necessary to ensure trap contaminant concentrations

are above analytical detection limits. An example sampling regime used in

previous laboratory investigations consisted of sampling at intervals of 6 hr, 24

hr, 7 days, 10 days, and 14 days.

A sample laboratory schematic is shown in Figure F-2.

Appendix F Laboratory Evaluation of Volatile Emissions and Volatile Dispersion Modeling