Colorado Clean-up Standards for Hydrocarbon Contaminated Soil and Groundwater

Tier 1 Risk-Based Screening Levels (RBSLs) and TPH Threshold Value

Media	Exposure Pathway	Land Use	Benzene	Toluene	Ethylbenzene	Xylenes	Naphthalene	TPH
Subsurface Soil	Leachate to Groundwater Ingestion	NA	0.26 mg/kg	170 mg/kg	200 mg/kg	1900 mg/kg	310 mg/kg	500 mg/kg
Surficial Soil	Ingestion/ Dermal/ Inhalation	Residential	4.1 mg/kg	4100mg/kg	2100 mg/kg	36000mg/kg	2,400 mg/kg	500mg/kg
Surficial Soil	Ingestion/ Dermal/ Inhalation	Industrial	12mg/kg	28000mg/kg	15000mg/kg	250000mg/kg	35,000 mg/kg	500mg/kg
Soil Vapor	Indoor Air Inhalation	Residential	2700µg/m³	> VP³	> VP³	> VP³	NA	NA
Soil Vapor	Indoor Air Inhalation	Industrial	35000µg/m³	> VP³	> VP³	> VP³	NA	NA
Groundwater	Indoor Air Inhalation	Residential	0.015mg/L	6.9mg/L	18mg/L	14mg/L	30mg/L	NA
Groundwater	Indoor Air Inhalation	Industrial	0.39 mg/L	490 mg/L	> Sol⁴	> Sol⁴	> Sol	NA
Groundwater¹	Groundwater Ingestion (MCLs)	NA	0.005mg/L	1.0 mg/L	0.68 mg/L	10 mg/L	NA	site specific

¹ The Subsurface Soil Leachate to Groundwater Ingestion and Groundwater Ingestion Pathway concentrations are considered the Action Levels.

² At sites where BTEX concentrations are below the Action Levels and TPH soil concentrations are above 500mg/kg, PAH analyses are required for the 16 Priority PAHs.

³ > VP denotes that even at a concentration equal to the vapor pressure of the chemical, a hazard quotient of 1 is not exceeded.

⁴ > Sol denotes that even at a concentration equal to the solubility of the chemical, a hazard quotient of 1 is not exceeded.

⁵ Not applicable for exposure pathway

Contact: Marilyn Hajicek, Colorado Department of Labor and Employment, Oil Inspection Section, 303-620-4032

Web Site: http://oil.cdle.state.co.us

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