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RBCA Tool Kit Exercise

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Groundwater protection : Tier 1 compliance point

Point ofcompliance=Point of exposure

(on site)

compliance point (receptor) are located closed to the source

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Tier 1 On - Site Off - SiteLand Use: residential NA

Gw Use: residential NA

4Note. All on site exposure pathways have been selected with residential land use. This scenario provides risk based cleanup standards, which are protective for unrestricted, land use.

1. GwExposure

Select Residential receptor and Affected groundwater andAffected soils as source media

2. Surface SoilExposure

Select Residential receptor and select constructon Workerexposure

3. Air Exposure Select Residential receptor and Affected Soils, Groundwater, andSurface Soils as source media for outdoor Air and Indoor Air.Also select Construction Worker exposure for Outdoor Air.

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4. Commands and Options: select Exposure factors and target Risks. Note that the default exposure parameters are already entered. Select return to exposure pathway, then main screen

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Exposure Factor and Target Risk Limits

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Note. The Exposure Pathways button is now green. Select Constituent of Concern

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Constituent of Concern

Select COCs: Select Add/Insert. Highlight Xylene (mixed Isomers) from the list of chemicals and choose Select. Also select Toluene ecc.

Rapresentative COC concentration: input directly the COC concentration data for GW and Soil or Click Claculate to enter Site Data.

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Costituent of Concern: Enter Site Data, if there are different measure point. In this case RBCA can evaluate the mean, the maximum, or the UCL value, depending on wich is the best approximation.

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1. Define Transport models

2. Define Soil, GW and Air Parameters

Main Screen

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1. Vertical Transport, Surface Soil Column. Select “Combination surface soil /Johnson & Ettinger models, for Outdoor air. Select Johnson & Ettinger model” for indoor air. Select “ASTM Model” for soil to GW leaching.

2. Command and Options: Select Main Screen.

Transport Models

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1. Select each parameter screen from the main screen and review the default parameters provided. Return to the main screen.

Note: All the input buttons have green dots indication that all required model inputs have been entered

• Soil Parameters

• GW Parameters

• Air Parameters

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Soil Paramaters

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Groundwater Paramaters

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Air Paramaters

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Review Output

Review the Exposure Flowchart, COC Chem Parameters, Input data Summary and User-Spec. COC data output screens to ensure that the model input parameters where entered correctly. Select Baseline Risks.

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Baseline Risks Select Risk by All Pathways. Record maximum individual COC risk levels on the table below

Outdoor Air Indoor Air Soil Groundwater

Carcirogen Risk 1.9E-6 4.9E-4 3.3E-6 6.6E-4

Hazard Quotient 9.2E-2 23 8.6E-2 2.7E+1

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• Which pathways controls the overall benzene RBSL for soil ?

Cleanup Standards. RBSL Soil

• What is the pathway specific RBSL for benzene for the Soil to indoor air Pathway? 0.015 mg/l

Soil leaching to gw

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What is the pathway specific RBSL for benzene and MTBE to groundwater ingestion ? (Benzene: 2.9E-3 mg/L; MTBE: 3.7E-1 mg/L). These are also the applicable RBSL for benzene and MTBE.

RBSL Gw

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Point ofcompliance

(edge of site)

compliance point (receptor) might be located at some distance from the source

Groundwater protection : Tier 2 compliance point

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Tier 2 On - Site Off - SiteLand Use: residential NA

Gw Use: none Residential, srf. water

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Main Screen 1. Which type of RBCA Analysis: select Tier 2. This allow calculation of SSTLbased on off-site receptors

2. RBCA Evaluation Process: Select Exposure Pathways.

ExposurePathways

1. Groundwater Exposure: set on-site receptor to None. Set off-site 1 to MCL.Set off-site 2 to S.W. (for Surface water discharge). Select swiming and fishconsumption for GW Discharge Water Exposure.

2. Gw Exposure: Under Distance to Gw receptor, enter 100 m for off-site 1 and200 m for off-site 2 for both affected groundwater and affected soils

3. Command and Options: Select Main Screen

Note: Transport models and Gw Parameters now require additional input. SlectTransport Models

Note: Select Set Units to change unit

TransportModels

3. Gw Diluition Attenuation Factor: select "Domenico equation with dispersiononly"

4. Command and Options: Select Main Screen. Select GW Parameters

GWParameters

4. Groundwater discharge to Surface Water. Enter 4500 cm for plume widthand 200 cm for plume thickness. Enter 100000 cm3/sec as the surface waterflowrate.

5. Command and Options: Select Main Screen

Note: All the input buttons have green dots indications that all required modelinputs have been entered.

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ExposurePathways

1. Groundwater Exposure: set on-site receptor to None. Set off-site 1 to MCL.Set off-site 2 to S.W. (for Surface water discharge). Select swiming and fishconsumption for GW Discharge Water Exposure.

2. Gw Exposure: Under Distance to Gw receptor, enter 100 m for off-site 1 and200 m for off-site 2 for both affected groundwater and affected soils

3. Command and Options: Select Main Screen

Note: Transport models and Gw Parameters now require additional input. SlectTransport Models

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Control the Exposure Pathway Flowchart to be sure the selected exposure pathways were correct.

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Transport Model Gw parametrs now require additonal information

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TransportModels

1. Gw Diluition Attenuation Factor: select "Domenico equation withdispersion only"

2. Command and Options: Select Main Screen. Select GW Parameters

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Gw parametrs now require additonal information

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GWParameters

1. Groundwater discharge to Surface Water. Enter 4500 cm for plume widthand 200 cm for plume thickness. Enter 100000 cm3/sec as the surface waterflowrate.

2. Command and Options: Select Main Screen

Note: All the input buttons have green dots indications that all required modelinputs have been entered.

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Review Output

Cleanup Standards Verify the applicable Soil and Gw SSTL on thefinal table (SSTL and CRF)

Baseline Risks. Groundwater What is the NAF value for the gw pathwayfor benzene? For MTBE?

Transient DomenicoAnalysis. Domenico ModSummary

What is the time to reach POE concentrationlimit for benzene at off-site receptor 1 for theGw pathway?

Transient DomenicoAnalysis. Transient AnalysisWorksheet

Select Benzene as the COC. Leave gw as thesource medium. On the Conc. vs Dist. graph,chenge the y-axis scale to log. Approximatelyhow long does it take Benzene conc. Toreach steady state at the off-site 1 receptor?From the Conc. vs Time graph, how longdeos it take for the benzene concentration toreach the MCL at off site 1 receptor?

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SSTL for Groundwater and Soil

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Baseline Risks.Groundwater

What is the NAF value for the gw pathway for benzene?For MTBE?(10; 10)

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Transient DomenicoAnalysis. DomenicoMod Summary

What is the time to reach POE concentration limit forbenzene at off-site receptor 1 for the Gw pathway?(7.9 E-1 Yr)

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Transient DomenicoAnalysis. Transient AnalysisWorksheet

Select Benzene as the COC. Leave gw as the source medium.On the Conc. vs Dist. graph, chenge the y-axis scale to log.Approximately how long does it take Benzene conc. To reachsteady state at the off-site 1 receptor? (3-4 yr)

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Transient Domenico Analysis.Transient Analysis Worksheet

From the Conc. vs Time graph, how long deos ittake for the benzene concentration to reach theMCL at off site 1 receptor? (0,9 yr)

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COC Chemical Parameters