KTC-03-03 / SPR 224-01-1F
"Environmental Impacts of Bridge Cleaning Operations", T. Hopwood II, S. Palle, R. Younce
ABSTRACT
Cleaning
(washing) operations of existing leaded paints on bridges were
studied to determine the level of lead
contamination in the resulting wastewater. Twelve experimental overcoating
projects were let on bridges with various
types of existing paint in varying states of deterioration. The projects
employed different washing pressures ranging from
2500 psi to 10000 psi and various wash nozzles (fan and 0o spinner
tips). KYTC standard filtration was used on 10
projects and 2 projects used an experimental filtration unit having
a sand filter and two types of chemical filter media.
Prior to painting, the existing paint was analyzed for thickness, adhesion,
and lead content. Wastewater generated
during maintenance painting operations (potable, unfiltered and filtered)
was sampled and analyzed for lead content
(total and dissolved), total suspended solids and pH. No clear correlations
were obtained between lead in the wastewater,
wash pressures, nozzle type, or any of the existing paint parameters
tested. The sand filter and chemical filter media of
the experimental filtration unit provided significant removal of lead
from wastewater.