LAND APPLICATION OF 25 YEARS OF PHOSPHORUS FERTILIZER PROCESSING RESIDUES

Chevron Chemical Company (Chevron) retained CH2M HILL to facilitate closure of their former fertilizer manufacturing plant in Ft. Madison, Iowa. One phase of this work was closure of the Complex Pond (Pond). The Pond received fertilizer by-products that were washed down by water from the fertilizer manufacturing process. Over time, solids (primarily calcium phosphate precipitates) accumulated in the bottom of the pond.Analysis of the solids indicated they contained appreciable quantities of phosphorus with a significant monetary value. Disposal to a landfill and reuse as a soil amendment were the two alternatives were evaluated:Following the alternatives analysis, it was determined the most environmentally safe, costeffective, and beneficial reuse of the solids was land-applying the materials. During fall 1998, Chevron proceeded with a program for land application of phosphorus fertilizer processing solids in Lee County, Iowa. Chevron provided the solids to the local farmers at no cost. The farmers paid for the transportation and land application costs.During fall 1998, Pond closure construction activities started. These activities included the following:Mobilizing subcontractors to the siteRemoving solids from the Pond and preparing solids for land applicationTransporting solids to farmlandsApplying solids to the fieldsTransporting Pond debris and low-quality solids offsite for disposalBack-filling, grading, and seeding the Pond areaRoughly 7,800 cubic yards (cy) of solids was excavated, processed, and applied to 2,143 acres of farmland. The land application program provided a significant positive influence on the agricultural economy of Lee County, Iowa, saved valuable landfill space, and provided a beneficial reuse of fertilizer by-products.