Vironex Environmental Field Services

Soil Vapor Sampling
There are four primary soil vapor sampling methods using Direct Push Technology (DPT) in conjunction with the Vacuum Volume System:

In Line Sampling
Tedlar Bag Sampling
Summa Canister Sampling
Monitoring Points

In Line Sampling
A common practice when a mobile laboratory is on site and the client desires immediate results.
Tedlar Bag Sampling
Used when the client wishes to capture the soil vapor sample for shipment to a fixed lab, or in cases where the sampling is proceeding rapidly and the on site mobile laboratory requires temporary storage.
Summa Canister Sampling
Is less common, however, it offers a reliable method for collecting, storing and shipping samples to a fixed laboratory.
Monitoring Points
Can be installed for extended soil vapor monitoring.
Soil vapor collection is accomplished using the following tools and a supplies:

Expendable Drive Point
Expendable Point Holder
PRT Adapter
Tubing (typically polyethylene or Teflon)

Soil Vapor Sampling
Vironex uses Direct Push Technology (DPT) to collect soil gas samples to depths in excess of 50 feet below ground surface (bgs) in most soil conditions. Each DPT rig is equipped with a Vacuum/Volume System Pump and a Direct Read Flow Meter. Vironex utilizes the Geoprobe Post Run Tubing (PRT) System with Ľ-inch polyethylene tubing and expendable or retractable drive points.
Soil Vapor Sampler Standard Operating Procedure
California's Interim Final Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air

	5 Feet Sample Depth	10 Feet Sample Depth	15 Feet Sample Depth	20 Feet Sample Depth	25 Feet Sample Depth	30 Feet Sample Depth	35 Feet Sample Depth	40 Feet Sample Depth
One Purge Volume	28.3 ml 0 min 8.4 sec	50.6 ml 0 min 15.1 sec	72.9 ml 0 min 21.8 sec	95.2 ml 0 min 28.5 sec	117.5 ml 0 min 35.2 sec	139.8 ml 0 min 41.94 sec	162.1 ml 0 min 48.6 sec	184.4 ml 0 min 55.3 sec
Three Purge Volumes	50.6 ml 0 min 15.4 sec	95.2 ml 0 min 28.5 sec	139.8 ml 0 min 41.9 sec	184.4 ml 0 min 55.3 sec	229.0 ml 1 min 8.7 sec	273.6 ml 1 min 22.0 sec	318.2 ml 1 min 35.4 sec	362.8 ml 1 min 48.8 sec
Six Purge Volumes	139.8 ml 0 min 41.7 sec	237.6 ml 1 min 22.0 sec	407.4 ml 2 min 1.0 sec	541.2 ml 2 min 42.3 sec	675.0 ml 3 min 22.5 sec	808.8 ml 4 min 2.6 sec	942.6 ml 4 min 42.8 sec	1,076.4 ml 5 min 22.9 sec

Purge Calculations:
1. Tubing (0.25 in OD, 0.17 inch ID)
a. Volume = 4.46 ml per foot internal volume
2. Vapor Point Holder and Post Run Tubing Adapter
a. Volume = 6 ml internal volume

Volume Formula: A (B x C) + D = E
A = Number of Purge Volumes
B = 1 foot of tubing, 4.46 ml
C = Depth
D = Point Holder, 6 ml
E = Volume to be purged

Time Formula (F ÷ E) x G = H
E = Volume to be purged
F = Purge Rate, 200 ml (cc) per min
G = 60 seconds
H = Purge Time in seconds at 200 ml (cc) per min

Los Angeles Regional Water Quality Control Board Soil Vapor SOP
San Mateo County Soil Vapor Guidelines