On-Site Incineration at Weldon Spring Ordnance Works, St. Charles County, Missouri

Site Name:

Former Weldon Springs Ordnance Works


St. Charles County, Missouri

Period of

- Trial Burn - 8/14/98 to 8/16/98
- Interim Operation - 8/17/98 to 9/18/98
- Full-Scale Operation - 9/19/98 through 1999


Full-scale Remedial Action


Mr. Alan J. Zupko
Roy F. Weston, Inc.
1 Weston Way
West Chester, PA 19380-1499
(610) 701-3623

On-Site Incineration
- Excavated pipeline and combustible debris were shredded.
- Soil and shredded materials were fed through a screen to remove large debris.
- The incineration system consisted of a co-current, rotary kiln and a secondary combustion chamber (SCC).
- The kiln operated at an exit gas temperature above 1626°F and the SCC operated above 1823°F.
- Hot gases exiting the SCC passed through a two-stage spray tower and two pulse-jet baghouses in parallel.
- Treated soil and fly ash were stockpiled for compliance sampling.
- Treated soil and fly ash that met treatment standards were used as fill material at the site.

Cleanup Authority:
CERCLA and State Record of Decision (ROD) date - May 1996

Regulatory Points of Contact:
Mr. Tom Lorenz
U.S. EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7292

Mr. Ray Strebler
Missouri Department
of Natural Resources,
Hazardous Waste Program,
Division of Environmental Quality
P.O. Box 176
Jefferson City, MO 65102-0176
(573) 751-7241
Project Management:
Mr. Dan Mroz
USACE, Kansas City District
601 E. 12th Street
Kansas City, KS 64106
(816) 983-3567

Captain Jim Workman
Big Piney Building
1018 P.O. Box 200
Ft. Leonard Wood, MO 65473
(314) 498-5176

- 2,4,6-Trinitrotoluene (TNT) and 2,4- and 2,6-Dinitrotoluene (DNT)
- Maximum concentrations:
  - 510,632 mg/kg TNT
  - 7,100 mg/kg 2,4-DNT
  - 200 mg/kg 2,6-DNT
- Some soil contaminated by lead, asbestos, PCBs, and PAHs

Waste Source:
Discharge and leaks/spills of contaminated wash water and wastewater; open burning of explosives

Type/Quantity of Media Treated:
- An estimated 30,000 tons (18,000 cubic yards (CY)) of nitroaromatics-contaminated soil
- An estimated 85,230 linear feet of nitroaromatics-contaminated wooden pipeline
- Average Moisture Content: 18%
- BTU Value: 60 Btu/lb
- Pipeline: 1 linear foot weighed approximately 25 pounds; the shredded density was 0.43 tons/CY

Purpose/Significance of Application:
To provide permanent destruction of nitroaromatics-contaminated materials; no long-term waste management requirements following on-site backfill of incinerator ash.

Regulatory Requirements/Cleanup Goals:
- Destruction and Removal Efficiency (DRE) of 99.99% for POHC.
- Regulatory limits for treated soil and fly ash after incineration were 57 ppm TNT and 2.5 ppm 2,4- and 2,6-DNT.
- Treated soil and fly ash with TCLP values in excess of 5 mg/L lead were stabilized.
- Air emission requirements included control of metals, hydrogen chloride, chlorine, 2,3,7,8-tetrachlorinated dibenzo-p-dioxin toxic equivalents, carbon monoxide, total hydrocarbons, nitrous oxides, particulate matter and opacity in the stack gas.

- Sampling of treated soil and fly ash indicated that the soil and pipeline cleanup goals were met.
- Emissions data from the trial burn, interim operations and full-scale operations indicated that all emissions standards were met.

Cost Factors:
- The total cost for this project was $13,665,997. This cost is for all remedial activities performed at the site, including incineration.

The former Weldon Spring Ordnance Works included a nitroaromatics manufacturing facility operated by the Army between 1941 and 1945. Wash water and wastewater generated in the TNT and DNT production plants were discharged to settling lagoons at the WSOW prior to mid-1942 and to wastewater treatment plants via an underground wooden pipeline after mid-1942. Leaks and spills occurred at the production buildings and the wastewater pipeline. Open burning was used to dispose and/or treat off-specification material, surplus product and contaminated soil.

Nitroaromatics were detected in surface soil, shallow subsurface soil, groundwater and springs at the former WSOW. A ROD was signed in September 1996, specifying on-site incineration as the remedial technology for addressing nitroaromatics-contaminated soil and wooden pipeline at the site. Contaminated soil and pipeline at the former WSOW was identified as Operable Unit (OU) 1. Site cleanup goals were specified in the ROD.

Site work for construction of the incinerator was commenced in December 1997. Incinerator start up and shake down were performed in July and August 1997. The trial burn was conducted in August 1998. After receiving approval from EPA and MDNR of the proposed operating limits, the incinerator was put into full-scale operation in September 1998. Treatment was completed in April 1999.The incineration system consisted of a co-current, rotary kiln followed by a SCC. After confirming that treated soil and fly ash met the cleanup criteria, the materials were backfilled at the site. Demobilization of the incinerator from the site was completed in 1999.