Underground Storage Tanks Program

Northwest Total Petroleum Hydrocarbon Analytical Methods

The UST Cleanup Rules (OAR 340-122-0218(d)(A)) require the use of the Northwest Total Petroleum Hydrocarbon (NWTPH) Analytical Methods for samples "used to demonstrate compliance with remediation levels." The NWTPH methods were developed to satisfy UST cleanup rules in both Oregon and Washington. These methods include:

• NWTPH-HCID
  which is a qualitative and semi-quantitative screen to determine the presence and type of petroleum products that may exist in water or soil. This method may be used in place of the current TPH-HCID.
• NWTPH-Gx
  which is a qualitative and quantitative method for volatile petroleum products such as aviation and automotive gasolines, mineral spirits, Stoddard solvent and naphtha. This method may be used in place of the current TPH-G.
• NWTPH-Dx
  which is a qualitative and quantitative method for semi-volatile petroleum products such as jet fuels, kerosene, diesel oils, hydraulic fluids, mineral oils, lubricating oils and fuel oils. This method may be used in place of the current TPH-418.1 Modified or TPH-D.

For more information:

• View the Northwest TPH Analytical Methods on the DEQ Laboratory's Web Site.
• To obtain a printed copy of the Northwest TPH Analytical Methods, please call the UST Cleanup Program's information request line, 1-800-742-7878 (toll-free within Oregon), or DEQ's Land Quality Division, 503-229-5913. Copies may also be obtained from UST Program staff in any of the DEQ Regional Offices.
• Laboratory personnel with specific technical questions about the methods should contact the manager of DEQ's Organic Analytical and General Chemistry Lab, at 503-693-5745.

[print version]