. EXISTING PAVEMENT
CONDEMNED PROPERTY I
ROADSIDE' MEDIAN -"
expansion through urban
areas typically require
condemnation of expensive
commercial and residential
ROADSIDE TREATMENT SWALES
Within the basin of this impact, there are usually numerous untreated discharges entering
the same water body. In some cases, these untreated discharges emanate from areas that
have poor drainage, and residents are unable to afford an appropriate retrofit project to
remedy these water management problems. The environmental result associated with
expending resources to address such problems may be better than what would result from
building a stormwater treatment facility for the new or expanded road. Additionally, the
social benefits derived from addressing the existing urban problem may far outweigh any
social benefit that may be attributed to treating the road's stormwater drainage.
Figure 9 is an illustration of a hypothetical situation that involves a highway expansion
through an urban/commercial area adjacent to the Indian River Lagoon. Here an existing
two-lane road is planned for expansion to a four-lane divided highway with conventional
water quality treatment. Even the bridged portion of the expansion has some type of water
quality treatment. This approach requires that for a two-mile road expansion,
approximately 20 acres of additional right-of-way be acquired for the purpose of
accommodating the water quality treatment. The additional cost associated with providing
the land and facilities for the conventional treatment is in excess of $15 million.
In addition to the direct economic costs, the resulting road project requires the
displacement of three homes, reduces the parking of adjacent businesses, and results in an
unsightly and potentially dangerous open water management system. Due to the typically
high water tables that are found in areas adjacent to the lagoon, these swales and ponds
will have standing water in them most of the time, thus creating increased maintenance
The project area depicted in the examples is located in an older part of the municipality and
is typical of Florida development of the late 1950's and early 60's. Single family homes
were built at or near grade with unpaved roads for access and septic tanks for sewage
treatment. The neighborhood is subject to occasional street flooding, inoperative or failing
septic systems, and during minor rain events, the dirt roads wash into the lagoon creating
considerable harm to the estuary.
If water quality mitigation was acceptable and the maximization of the environmental
result per dollar spent was the goal, a more beneficial outcome is possible. Figure 10
illustrates how the alternative system might be configured. The design incorporates some
treatment of the run-off from the new road pavement by the use of swales and sediment
trap catch basins. The emphasis, however, is placed offsite at the described neighborhood.
Here the roads are paved, a treatment system is in place and some fiscal resources are