Anatomy of Microbially Induced Corrosion of Concrete Lined

Sewers

Harry R. Price, P.E. John R. Kosnak, P.E. NTH Consultants, Ltd.

Microbe succession diagram

After Microbial Ecology of Crown Corrosion in Sewers, Islander et al., ASCE Journal of Environmental Eng., V. 117, No. 6,1991

System History

• Majority constructed 1970 to 1975 • One section in late 1980’s and one section in early 2000’s • Tunnel Failures in 1978, 1980 and 2004 • Microbially Induced Corrosion (MIC) not visible in 1980’s • High levels of H2S observed during repairs 2004/2005 • Substantial MIC observed in 2006, 2007, 2008, 2010 and

2011 condition investigations

Scaling Spalling Over Reinforcing Steel

Hydraulic Jump

Reinforcing Steel

Missing Aggregate

Projecting Aggregate

Dry weather flow line

Scaling

Corrosion Product

Projecting reinforcing steel

Scaling

HARRY PRICE HPRICE@NTHCONSULTANTS.COM

Questions?