a detailed evaluation procedure are described to provide
guidance on determining the most appropriate methods for
performing stormwater monitoring.
and when choosing sampling locations.
•;Bacteria growth within sampling streams can cause
problems for both the accuracy of the tests and
the maintenance of monitoring systems. Preventive
measures vary with the parameters being tested for, but
can include chlorination or water-jet cleaning systems.
Having identified appropriate monitoring methods, airports
should compare capital and annual costs analysis on
the methods and support systems. The costs involved in
monitoring the parameters include utilities, consumables,
operation labor, maintenance labor, laboratory analytical work,
and replacement and repair.
IMPLEMENTATION BEST PRACTICES
Once parameters and monitoring methods have been
determined, airports can begin selecting needed materials and
implementing the monitoring process at sampling locations.
While methods must be selected to custom fit the needs of
each airport, there are general implementation guidelines that
should be observed:
Long-term utility needs at the sample site include
potable water supplies for cleaning systems; a heating
system, particularly for solutions with minimum
recommended storage temperatures; and, depending
on the summertime climate, air-conditioning or other
•;Collect samples where the sample stream is well-mixed to ensure accurate monitoring of all parameters.
Typically, turbulent streams or streams flowing in a
concentrated area provide well-mixed samples. Avoid
sampling locations where flow is not mixed well, such as
near outfalls or surface water, or where two flows join.
Regular and skillful maintenance is critical and should be
taken seriously. A regular maintenance routine should
check for functioning of equipment, replace worn or broken
tubing, check and replace calibration standard fluids, and
replace malfunctioning probes. Preventive maintenance
should be performed during the off-season as well.
For more detailed information on monitoring systems
and models, cleaning systems, maintenance plans, and
best practices, go to http://www.trb.org/Publications/
•;As most sampling will occur during the winter, weather
hazards should be accounted for in implementation plans
Mark R. Ervin, P.E., is senior environmental engineer for Gresham,
Smith and Partners. He may be reached at email@example.com.