RISC - Risk-Integrated Software for Cleanups

In 1993, BP made a business decision in the U.S. to develop a standardized approach for conducting soil and groundwater risk assessments across all ‘downstream’ activities (service stations through refineries). The rationale was that the company needed to ensure that the latest thinking on fate and transport, exposure, statistical analyses and toxicological criteria were adopted and applied uniformly across its businesses. It would also help ensure that BP spoke with a consistent voice when approaching regulators and the community on this vital issue. Eventually it became clear that a software package containing embedded fate and transport models with intuitive user inputs offered the most convenient and flexible means of implementing this objective. This would enable the process to be readily standardized, communicated and transferred, while still allowing a risk application to be individually tailored to the regulatory regime of the particular business or country. By developing the code in-house, BP would also be able to rapidly adopt new algorithms or approaches (e.g. indoor air models), thus keeping the process evergreen.  RISC (previously referred to as BP RISC) Versions 1.0 and 2.0 of the code were released in January, 1994 and August, 1995, respectively, with the former pre-dating the publication of the ASTM standard Risk-Based Corrective Action Applied at Petroleum Release Sites, commonly known as RBCA . Version 3.0, released in September, 1997, was a major upgrade that allowed back-calculations to be performed, i.e. soil and groundwater clean-up targets to be calculated for an input value of acceptable risk.

• Customizable chemical database with more than 100 chemicals.
• An excel spreadsheet based on the RBCA algorithms that can be used to replicate the tiered RBCA process.
• Detailed user's manual with three in-depth example problems.
• Ability to determine risk-based TPH (total petroleum hydrocarbon) targets using the TPH fractions proposed by the U.S. Air Force led TPH Working Group.
• Ability to calculate additive risk due to multiple pathways, compound and receptors (such as a resident exposed as both a child and an adult).
• Monte Carlo capabilities for probabilistic risk evaluation.
• Fate and transport models that distinguish between presence or absence of phase-separated product (NAPL) in the source zone.

• Irrigation pathways, i.e. water used for gardening but not for indoor usage
• Vegetables grown in contaminated soil
• Two new vapor models , where the vapors are allowed to biodegrade during transport through the unsaturated zone
• Models for surface water and sediment contamination from impacted groundwater and direct comparison with relevant national standards for these media
• The use of groundwater MCLs (maximum concentration levels) and surface water concentrations in addition to acceptable risk levels as the criteria for back-calculating clean-up targets
• The ability to calculate a site-specific target level (SSTL) for a TPH mixture using the site-specific measured concentrations of the TPH fractions detected in the soil

• Food web screening models for terrestrial and aquatic ecological risk assessments
• Output tables and charts are now created directly in Excel
• Particulate emission model added
• New plant uptake model (Trapp and Matthies, 1995)
• RISC5 model chemical database has been expanded to ~120 chemicals (from 80)
• User can choose to use either reference concentrations and unit risk factors, or,  inhalation reference doses and inhalation slope factors
• All chemical toxicity values updated to be current with USEPA values
• Chemical database is much easier to edit and generate summary tables of chemical properties
• Mass balanced, depleting source, added to indoor and outdoor air models
• References provided (on-line and in Excel tables) for all chemical and receptor parameters
• New human receptor profiles added (including ones for additive receptor
• User can add new receptor and soil profiles and/or may customize default values
• Sediment was added as a media of concern for human health risk (dermal contact and ingestion exposure pathways)
• New databases:
  Ecological receptors and receptor-specific information, mammalian and avian toxicity values, worm and plant toxicity values, soil and plant screening values

• Ingestion of soil
• Dermal contact with soil
• Ingestion of groundwater
• Dermal contact with groundwater
• Inhalation in the shower
• Inhalation of outdoor air
• Inhalation of indoor air
• Ingestion of surface water
• Dermal contact with surface water

• Johnson and Ettinger indoor air model
• Volatilisation from groundwater to indoor and outdoor air
• Outdoor box model
• Unsaturated zone model
• Saturated zone model

• Estimate human health risk from exposure to contaminated media,
• Estimate risk-based clean-up levels in various media,
• Perform simple fate and transport modeling, and
• Evaluate potential ecological impacts to surface water and sediment.