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ADVISORY—ACTIVE SOIL GAS INVESTIGATIONS <br /> Figure 1 <br /> Typical Single and Nested Soil Gas Probe Design & Purge Volume Calculabon <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.teflon@) <br /> T T <br /> DBT -1 Ft Dry Granular Bentonite DBT <br /> ST Probe Tip ST <br /> [-*-BD ��---1 Ft Sand j <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 <br /> SV= sand pack volume (ml) T <br /> TL =tubing length (ft) --1 Ft Sand DBT <br /> TLV=tubing linear volume (ml/ft) _X_ <br /> TV =tubing volume (ml) <br /> PEEK= Polyetheretherketone ST <br /> 1-0-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 = <br /> X 350 if BD = 2 1/8" _ <br /> (2) DBV= DBT x BLV = (DBT) X 820 if BD = 3 1/4" = 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 '/4" = 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 />