Soil Sampling and NAPLANAL

Transcription

1 ESTCP Soil Sampling and NAPLANAL Duke Engineering and Services SEAR Workshop

2 Representative Elementary Volume (REV) S r v 2 v 1 v 0 S r Domain of Microscopic Effects Domain of Porous Medium The Accuracy of Soil Samples The Accuracy for Remedial of Soil Design Samples for Remedial Design Domain of REV Inhomogeneous Medium Homogeneous Medium v 0 v 1 v v 2 Est. range of REV for NAPL in soil = cm 3 = to 0.3 ft 3 Volume of typical soil sample = cm = to 0.01 ft 3 SEAR Soil Sampling and NAPLANAL 2

3 DNAPL in Soil from OU 2, Hill AFB, UT SEAR Soil Sampling and NAPLANAL 3

4 DNAPL Soil Sampling Focus Average Saturation N SEAR Soil Sampling and NAPLANAL 4

5 Calculating Saturation Feenstra et al. (1991) Assesses whether NAPL is present Mott (1995): SOILCALC Assesses presence of NAPL Estimates NAPL composition Assumes NAPL does not occupy pore space, can t calculate S N Mariner et al. (1997): NAPLANAL SEAR Soil Sampling and NAPLANAL 5

6 NAPLANAL SEAR Soil Sampling and NAPLANAL 6

7 Partitioning Theory DNAPL AIR WATER SOLID SEAR Soil Sampling and NAPLANAL 7

8 NAPLANAL Calculates: NAPL saturation NAPL composition VOC concentrations in each phase NAPL composition and volume in water-napl emulsions ( s = 0) SEAR Soil Sampling and NAPLANAL 8

9 SEAR SEAR Soil Sampling and NAPLANAL 9 i s s s i n n i a a i w w i t t C C C C C s s n n a a w w t Mass of i = sum of mass of I in all phases: Total density = weighted average of all densities: Conservation of Mass

10 NAPLANAL Needs FIELD Total concentrations for each component Volumetric water content Soil porosity f oc DATABASE K oc for each component K H for each component Molecular weight of each component Densities Soil, water, air, NAPL SEAR Soil Sampling and NAPLANAL 10

11 How to Sample Objective: Recover all the sediment and the interstitial fluids! Types of samplers Solinst Cohesionless Sediment Sampler Fine-grained soils Split Spoon Coarse-grained soils CME Continuous Tube (wireline) Cryogenic sampler (USGS) SEAR Soil Sampling and NAPLANAL 11

12 Soil Sampling Methods Continuous sampling throughout the zone of interest: Get samples from critical zones But you can save $$ if you do not need upper zone sampled SEAR Soil Sampling and NAPLANAL 12

13 Soil Sampling Methods (cont.) Direct push Geoprobe with plastic tube sample liners Advantage Low cost if conditions are well suited Limitations Depth and coarse-grained or resistant sediments SEAR Soil Sampling and NAPLANAL 13

14 Soil Sampling Methods (cont.) Things to avoid Wash rigs (lots of water flooding) Air rigs (lots of SVE) Miscommunication with the driller SEAR Soil Sampling and NAPLANAL 14

15 How to Sample Things to do (EPA Method 5035) Use in-the-field preservation (methanol)...volatilization losses can randomly reduce VOC concentrations by one to three orders of magnitude. Hewitt et al., 1995 EnCore sampler SEAR Soil Sampling and NAPLANAL 15

16 Soil Sampling Protocols SEAR Soil Sampling and NAPLANAL 16

17 Procedure Prepare Core Sub-sample Screen (PID) Log Photograph Weigh and record SEAR Soil Sampling and NAPLANAL 17

18 Preparation Get Amber jars, methanol, scale (2,000 gm) Permanent ID (methanol dissolves labels and ink!) Tare jars Fill jars (50 ml for coarse sediment) Weigh and record Don t forget replicates and blanks! SEAR Soil Sampling and NAPLANAL 18

19 Sample Fast! 2 parts methanol to 1 part soil (make a dummy) Don t splash! Clean threads and tighten lids Put on ice Tighten lids SEAR Soil Sampling and NAPLANAL 19

20 Ship Weigh and record Pack well and use adsorbent Label and ship properly Flammable Numbers 24-hr phone SEAR Soil Sampling and NAPLANAL 20

21 NAPLANAL Input NAPLANAL Field Sample name/id Vadose or saturated zone Porosity or water content f oc Number of NAPL components Example Input LC34B10-15 Saturated Porosity ~ 30% f oc = components c-dce, PCE, TCE, t-dce SEAR Soil Sampling and NAPLANAL 21

22 NAPLANAL Input (cont.) Target analytes expressed in the form: mg contaminant kg soil SEAR Sample Depth c-dce PCE TCE t-dce ft bgs mg/kg mg/kg mg/kg mg/kg LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B LC34B SEAR Soil Sampling and NAPLANAL 22

23 NAPLANAL Solves In saturated zone, a and C a = 0 User picks or w as unknown In vadose zone, you need to know w Water sample: porosity = 1.0 SEAR Soil Sampling and NAPLANAL 23

24 NAPLANAL Output Sample Name Identification: LC34B10-15 Model used: Liquid saturated & porosity known Porosity (Volume Frac.): 0.3 Fraction organic carbon (f oc ): NAPLANAL ANALYSIS RESULTS: Name c-dce PCE TCE t-dce (mg/kg)* = mg per kg of soil sample (wet soil) (mg/kg)^ = mg per kg of solid (dry soil) Water Volume Frac. (L/L) Bulk Density (kg/l) NAPL Volume Frac. (L/L) NAPL Density (kg/l) Soil Volume Frac. (L/L) 0.7 Porosity (Volume Frac.) 0.3 NAPL Saturation (%) SEAR Soil Sampling and NAPLANAL 24 SEAR Total Mass (mg/kg)* Mass in Water (mg/kg)* Mass in Soil (mg/kg)* Mass in NAPL (mg/kg)* Conc. in Water (mg/l) Sorbed in Soil (mg/kg)^ Conc. in NAPL (kg/l) Mole Fraction in NAPL

25 Presence of DNAPL in Soil For OU 2, Hill AFB soil with: f oc =.0001 = 0.28 moisture content =.09 TCE > 345 mg/kg TCA > 62 mg/kg PCE > 23 mg/kg SEAR Soil Sampling and NAPLANAL 25

26 Other Soil Data Total VOC concentration Bulk density Soil f oc : TOC - minus VOCs! Porosity Grain size XRD: Clay minerals Wettability Capillary desaturation SEAR Soil Sampling and NAPLANAL 26

27 Characterizing Capillary Barriers Clay type (XRD) Entry pressure Mercury intrusion Centrifuge Pressure cell Gamma logging contacts Cone penetrometer data SEAR Soil Sampling and NAPLANAL 27

28 Any Questions? SEAR Soil Sampling and NAPLANAL 28