Kleinfelder Inc.

Kleinfelder Inc. Chemical is mixed with effluent for one cell (top). Pipe distributes water to manure mixture (below).

Soaking a decommissioned wastewater lagoon with manure and industrial graywater seems an odd way to remediate contaminated soil, but a Kansas gunpowder maker has saved money while reducing its potassium perchlorate contamination.

“We wanted to initiate a voluntary cleanup as a good neighbor,” says Doug Delsemme, vice president and general counsel at Hodgdon Powder Co., Shawnee, Kan. The U.S. Environmental Protection Agency has not established a maximum contaminant level for potassium perchlorate, but the compound, an oxidizer widely used in propellants, is suspected of affecting thyroid function, says Jean Underwood, Post-Remediation Unit chief at the Kansas Dept. of Health and Environment. In 2002, KDHE detected the substance in monitoring wells near Hodgdon’s Herington, Kan., plant. The site was entered in the State Cooperative Program.

Hodgdon was treating effluent to secondary levels from an onsite 3,000-gallon-per-day wastewater plant and trucking it offsite at considerable cost. Last spring, Kleinfelder Inc.’s Topeka office began a remediation plan on three cells composed of 16,000 cu yd of soil that had once held wastewater lagoons.

On one cell, workers applied water mixed with 7,500 lb of calcium magnesium acetate (CMA) Hodgdon had purchased for remediation. On the other two, local contractor Ted Long Excavating plowed in manure from a neighboring cattle feedlot, then constructed a grid of 2-in.-dia PVC pipes in 10-ft squares to distribute effluent from Hodgdon’s wastewater plant. The manure and the effluent together performed as electron donors to degrade the perchlorate in the soil, with the effluent also adding moisture for the process.

After four months, contamination in all three cells had dropped an average of 95% from levels as high as 45 mg per kg. But the effluent and manure were free and the owner avoided disposal costs, while CMA cost $1 per lb, says Jeff Gill, Kleinfelder staff professional. Total cost came to $243,000, but Gill estimates the use of effluent and manure would save $91,000 per year. The final closure sampling is scheduled for February.