LDEQ’s RECAP

Soil Protective of Groundwater - SoilGW

Soil Saturation - Soilsat

SoilGW values are soil concentrations for constituents of concern that are protective of a groundwater use

Soilsat values are the maximum soil concentrations allowed for constituents of concern. Above Soilsat free product is assumed to exist.

SOILGW & SOILSAT

1. Identify the appropriate GW classification ex. Shallow groundwater - GW3NDW

Determine the GW value for the COC ex. COC is Benzene, GW3NDW = 0.013 mg/l < Watersol

2. Use GW value to calculate Csoil

ex. Csoil = 0.00668 = 7.1

)228.0*15.021.0006.0*7.61*7.1(013.0

MO-1: Determination of SoilGW forOrganic COC

3. Multiply Csoil by vertical DF of 20 ex. SoilGW = 0.00668 * 20 = 0.13

4. Multiply SoilGW by DF from Table in Appendix I ex. From Table x = 300 & Sd = 10 then DF = 15

SoilGW3 = 0.13 * 15 = 1.95

MO-1: SoilGW Organic COC cont.

5. If the SoilGW3 value from Step 4 is lower than the next more protective groundwater classification SoilGW value then use the more protective groundwater classification SoilGW value

ex. SoilGW3 = 1.95 SoilGW2 = 0.051

SoilGW3 > SoilGW2

Therefore, use SoilGW3 as the SoilGW value

MO-1: SoilGW Organic COC cont.

Soilsat = 900 =

Soilsat is not applicable to constituents that are in the solid phase at ambient temperatures (i.e., constituents having melting points less than or equal to 20o C)

7.1

)228.0*15.021.0006.0*7.61*7.1(1750

MO-1: Determination of Soilsat

If TCLP level available: SoilGW = TCLP level * 20

If TCLP level not available: SoilGW = GW1 * 100 * 20

MO-1: Determination of SoilGW for Inorganic COC

1. Identify the appropriate GW classification ex. Shallow groundwater - GW3NDW

Determine the GW value for the COC ex. COC is Benzene, GW3NDW = 0.013 mg/l < Watersol

2. Use GW value to calculate Csoil

ex. Csoil = 0.00668 =7.1

)228.0*15.021.0006.0*7.61*7.1(013.0

MO-2: Determination of SoilGW

Method 1-Organic COC:

3. Multiply Csoil by site-specific DF SoilGW3 = 0.00668*DAFSummers*DAFDomenico

4. If the SoilGW3 value from Step 3 is lower than the next more protective groundwater classification SoilGW value then use the more protective groundwater classification SoilGW value

SoilGW3 = 0.00668*DAFSummers*DAFDomenico > or < SoilGW2

If SoilGW3 > SoilGW2 use SoilGW3

If SoilGW3 < SoilGW2 use SoilGW2

MO-2: SoilGW

Method 1-Organic COC cont.

If TCLP level available: SoilGW = TCLP level * 20

If TCLP level not available: SoilGW = GW1 * 100 * 20

MO-2: Determination of SoilGW

Method 1-Inorganic COC

This method may be used when the following conditions are met:

Groundwater and soil data are available,

Groundwater concentrations are less than soil concentrations, and

Groundwater data indicate the RS GW value has been exceeded

MO-2 Determination of SoilGW

Method 2-Organic and Inorganic COC

1. Calculate site specific water/soil partition coefficient to determine SoilGW

SoilGW = (SoilSS / GWSS) * GW1,2 or 3

GWSS & SoilSS - site-specific values (see footnotes on sample requirements p. I-49)

GW1,2 or 3 - refer to Table

2. Multiply SoilGW by appropriate site-specific DF

MO-2: SoilGW

Method 2-Organic and Inorganic COC cont.

MO-2: Determination of SoilGW

Method 3-Organic and Inorganic COC

Synthetic Precipitate Leaching Procedure (SPLP) - Used to evaluate Soil Protective of GW

- SW-846 Method 1312

- SPLPConcentration < (GW RS)(20)(DAF) then SoilGW is not an issue

How is the SPLP data used to evaluate the soil to gw pathway?

SoilGW1: Compare SPLP to GW1 x DFSummers

SoilGW2: Compare SPLP to GW2 x DFSummers x DF2

SoilGW3: Compare SPLP to GW3 x DFSummers x DF3

MO-2: Determination of SoilGW

Method 3-Organic and Inorganic COC

If SPLP <, then screen out soil to gw pathway

If SPLP >, then delineate area of concern

SPLP vs TCLP

SPLP vs LRS

MO-2: Determination of SoilGW

Method 3-Organic and Inorganic COC cont’d.

FIGURE I-1

SCHEMATIC DESCRIPTION OF DOMENICO’S MODEL

Impacted Area

Leachate

v Sd

z

y

x

SECTION

PLAN

v Sw

Source Area(Contaminated Groundwater)

Source Area(Contaminated Groundwater)

Csi

Csi

Sw

B

Infiltration Rate

Ground Surface

L

L