GrayLime: Development of an Environmentally Useful Co-Product Reuse Program, 1998 Environmental Conference Proceedings

Robert W. Martin

Grays Harbor Paper, L.P.

Jess A. Brown

Tetra Tech EM, Inc.

In 1994, the Grays Harbor Paper L.P. (GHP) initiated a beneficial reuse program utilizing the wastewater treatment primary clarifier solids (PCS) generated at their non-integrated paper mill located in Hoquiam, Washington. This program has operated successfully because GHP has partnered with the regulatory community and end users. GHP has successfully acquired and maintained an agricultural registration from the Washington State Department of Agriculture utilizing the PCS as an agricultural liming product under the trade name GrayLime. GHP has completed technical studies and continues to monitor product quality to support the GrayLime product registration and to provide usable product information for end users.

This presentation will provide an overview of the agricultural registration process in Washington, a summarization of the technical studies completed to support this project, and the GrayLime Land Application Program. These include an ongoing product characterization program, a laboratory pH incubation study and a two-year supplemental nitrogen field study. The objectives of these studies were to document product quality, to evaluate the pH-adjusting capacity of the GrayLime to calculate application rates, and to calculate the optimum amount of supplemental nitrogen required to balance the carbon applied with GrayLime.