The Excel spreadsheets and statistical packages on this page can help you plan cleanups, calculate cleanup levels, and show that your cleanup is happening as planned.
Tools just for petroleum contamination
Since about 95 percent of cleanup sites in Washington are contaminated by petroleum, we've assembled tools for cleaning up petroleum contaminated sites in one place. You'll find several of the tools on this page, plus extra guidance for managing the challenges of cleaning up petroleum contamination (known as "petroleum remediation").
A tip when using these tools: Select “Save” or “Save As” instead of “Open” when the download dialog box opens. Tools may not function correctly when opened directly from the website.
Statistical guidance and tools
These tools help you calculate compliance and background levels. They include tests you must use to show you’re meeting requirements of the state's cleanup law, the Model Toxics Control Act (MTCA). The statistical programs help you calculate upper confidence limits and background values for describing your site. It’s not always obvious what data means just by looking at it, so the statistical guidance can help.
- MTCAStat 97: Site Module allows you to calculate whether you’re in compliance with your site’s cleanup levels. It helps answer, for example: if one sample is above your cleanup level, does it mean your remediation failed?
- MTCAStat 97: Background Module allows you to calculate background levels at your site. Some of the harmful chemicals you’ll need to clean up can also occur naturally. This tool helps identify the “natural background level” for certain chemicals at your site so we can adjust your cleanup levels.
- Statistical guidance for Ecology site managers has information about compliance, background statistics, and toxics cleanup.
Workbooks for calculating cleanup levels
These tools allow you to calculate cleanup levels for two media:
- Soil using MTCA Methods B or C, and
- Groundwater using MTCA Method B.
These cleanup levels protect against harm from direct contact with soil. They also protect against harm from vapor inhalation and from petroleum leaching into groundwater and drinking water.
Although the tools can provide information about potential MTCA air quality concerns (Vapor Pathway), they do not provide air cleanup levels. For more information about the vapor pathway, please visit our Vapor Intrusion page.
Additional help for these workbooks
If you're new to the workbooks, check out the user's guide first. It answers questions, shows how to use the workbooks, and helps you understand your results: Workbook tools for calculating soil and ground water cleanup levels under the Model Toxics Control Act Cleanup Regulation: users guide 11.1.
Troubleshooting Excel compatibility helps address common problems when using different versions of Excel.
Natural attenuation of petroleum contaminated groundwater
Natural attenuation means relying on natural processes to decrease (or "attenuate") concentrations of contaminants in soil and groundwater. You can use this tool to predict when natural attenuation will allow groundwater cleanup levels to be met, or to demonstrate that levels have been met. This tool is split into two packages.
Package A will answer questions about:
- Plume stability.
- Length of time for groundwater concentrations to reach a target level.
- The site’s ability to break down contamination.
- The possibility that changing groundwater elevation is affecting concentrations.
Package B will answer questions about:
- Distance a dissolved plume will extend without intervention.
- Length of time until a target location reaches a cleanup level.
- Percent of mass that can be broken down naturally.
- Amount of source material that must be removed to let natural breakdown reach a target level by a certain date.
Additional help for the natural attenuation package
User's manual: Natural attenuation analysis tool package for petroleum-contaminated ground water (2005) provides guidance under MTCA on how to evaluate the feasibility and performance of natural attenuation for groundwater contaminated with petroleum hydrocarbons.