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ADVISORY—ACTIVE SOIL GAS INVESTIGATIONS <br /> Figure 1 <br /> Typical Single and Nested Soil Gas Probe Design & Purge Volume Calculation <br /> Surface <br /> Gas Tight Fitting <br /> Probe Box (optional) �~ <br /> Bentonite Grout <br /> (if permanent) <br /> or <br /> Hydrated Bentonite <br /> (if semi-permanent) <br /> Tubing <br /> (metal,nylon,PEEK,tefion0) <br /> W <br /> DBT -1 Ft Dry Granular Bentonite DBT <br /> ST Probe Tip ST <br /> I*-BD-►1 --`��-1 Ft Sand f <br /> TL <br /> Legend Bentonite Grout <br /> BD = borehole diameter(inches) (if permanent) <br /> or <br /> BLV=borehole linear volume (ml/ft) Hydrated Bentonite <br /> DBT=dry bentonite thickness (ft) (if semi-permanent) <br /> DBV=dry bentonite volume (ml) <br /> ID = tubing inner diameter(inch) -1 Ft Dry Granular Bentonite <br /> PV= purge volume (ml) <br /> ST=sand pack thickness(ft) Probe Tip--,_SV=sand pack volume (ml) <br /> T <br /> TL =tubing length (ft) --1 Ft Sand-. �t_� DBT <br /> TLV=tubing linear volume(ml/ft) `- <br /> TV=tubing volume (ml) ST <br /> PEEK=Polyetheretherketone <br /> I•-BD*-I <br /> X 6 if tubing ID=3/16" _ <br /> (1)TV=TL x TLV = (TL) X 16 if tubing ID =5/16" = ml <br /> X_if tubing ID = 4 = <br /> X 350 if BD= 2 1/8" _ <br /> (2) DBV= DBT x BLV = (DBT) X 820 if BD =3 114" = ml <br /> X if BD = <br /> X 280 if BD= 2 1/8" = <br /> (3)SV=ST x BLV= (ST) X 660 if BD= 3 114" = ml <br /> X if BD= <br /> Note: porosity of 50%used for dry bentonite and <br /> 40%used for#3 sand pack to calculate BLV. 1 PV= (1)TV+ (2) DBV+(3)SV= ml <br /> April 2012 11 <br />