Tools for cleaning up petroleum contaminated sites

Petroleum cleanup guidance

• Guidance for remediation of petroleum contaminated sites (2016) (also known as "TPH Guidance" or "Total Petroleum Hydrocarbons Guidance"). This document consolidates all the technical information for cleaning up petroleum-contaminated sites into one document. It also helps people learn how to meet the requirements of the state's cleanup law, the Model Toxics Control Act (MTCA), when cleaning up petroleum contamination.

• Guidance for Silica Gel Cleanup in Washington State (Nov. 2023) provides details on using silica gel cleanup (SGC) to analyz diesel and heavy oil range organics when using the Ecology's NWTPH-Dx analytical method for petroleum hydrocarbons at a cleanup site regulated under the Model Toxics Control Act cleanup regulations.

• Guidance on remediation of petroleum contaminated ground water by natural attenuation (2005) provides technical information for using natural attenuation to clean up petroleum contaminated groundwater. 

• Toxicity Data and Physical/Chemical Properties for Petroleum Mixtures (July 2024).

• Calculation of Method B and Method C cleanup levels for petroleum mixtures (Nov. 2023)

Tools

We’ve developed Excel-based tools to help you calculate cleanup levels for petroleum contaminated sites. The packages on this page are specific to sites with petroleum contamination. If you have a site with other contaminants, check out our contamination cleanup tools page.

Tip: Download the Excel files to your computer rather than opening in a browser. Tools may not function correctly when opened directly from the website.

MTCATPH Workbook Tool

The Workbook for calculating cleanup levels for petroleum contaminated sites (MTCATPH 12.0 Excel workbook version 12.0) is a tool that allows you to calculate cleanup levels for petroleum mixtures for 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 petroleum leaching into groundwater and drinking water. This tool does not include options for evaluating potential MTCA air quality concerns via the vapor pathway. For more information about the vapor pathway, please visit our Vapor Intrusion page.

We updated the workbook in April 2025 to include more soil leaching model outputs, including density of NAPL, volumetric NAPL content, and NAPL saturation (see section 3.3.4 of User's Guide).

MTCATPH workbook user's guide

• The User's Guide for the MTCATPH Workbook Version 12.0 answers questions about the tool, shows you how to use it, and helps you understand the results.

Natural attenuation of petroleum contaminated groundwater

This tool is split into two packages. Use them to predict when natural attenuation will allow groundwater cleanup levels to be met or to demonstrate that levels have been met. 

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.
• Open Package A of the Natural Attenuation Analysis Tool.

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.
• The percent of mass that can be broken down naturally.
• The amount of source material that must be removed to let natural breakdown reach a target level by a certain date.
• Open Package B of the Natural Attenuation Analysis Tool.

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.