KTC-03-30
"Evaluation of Methods to Protect Water Quality in Karst Areas: Phase I", J. Webster, D. Ramalingam, S. Palle
ABSTRACT
The primary focus of this report is
two-fold; to provide a literature review on what has been previously
learned about highway runoff in relation to karsts aquifers and to
characterize a karsts highway site in Kentucky that can be used to
evaluate a variety of best management practices. From research findings,
the main sources of pollutants in highway runoff came from vehicles,
atmospheric fallout, and precipitation. The behavior of pollutants and
their interaction with the environment can dictate where they will be
found and how to best minimize their effects. Although it would seem
that traffic volumes would greatly influence the accumulation of
pollutants on roadways, past studies have not proven this. Instead, no
clear relationship between traffic and water quality has been reported.
Removal processes such as air turbulence (both natural and the result of
vehicles) limit the accumulation of solids and other pollutants on road
surfaces, thereby obscuring the relationship between the traffic volume
and runoff loads. Of the various precipitation characteristics,
intensity was found to have the greatest impact on the type and quantity
of pollutants found in highway runoff. This was expected due to the
greater velocity traveled by runoff during high rain intensity events
which does not allow suspended particles a chance to settle out and
often results in greater friction along the runoff travel routes. In all
experiments previously conducted, highway paving material appears to
have minimal impact. Of the best management practices examined,
vegetated controls received the highest recommendation because of their
wide adaptability, low costs, and minimal maintenance requirements.
Water quality testing results from the location off I-65 South
demonstrated very low levels of select pollutants, when compared to
national averages. The existing vegetative controls in the highway
median and along the drainage paths are considered to be effective at
mitigating a large quantity of runoff from reaching the drainage point
into sinkhole.