If your industrial operations include
stormwater runoff, then the National Pollutant Discharge Elimination System (NPDES)
Permitting Program is one of your concerns. If you need to obtain a permit to
discharge storm water, part of that permit application includes collecting and
analyzing outflow samples, under fairly demanding meteorological conditions. The
Skywatch Weather Center can help you satisfy these requirements.
Valid outflow runoff sampling requires:
grab sample taken during the first 30 minutes of discharge due to the
flow-weighted composite sample taken during the entire event or during the
first 3 hours of the event
storm event must produce greater than 0.10 inches of precipitation
must be at least 72 hours of dry weather since the last storm event
variance in duration of the event should not exceed 50% from the average
or median storm event in the area*
variance in total rainfall of the event should not exceed 50% from the
average or median storm event in the area*
The documentation of the storm event
requires several items of information, some of which must be recorded on site,
and some of which require access to meteorological information on a continuous
basis for your area. These data include:
of the storm event
of the storm
rainfall recorded during the storm event
of hours since the previous measurable storm event
maximum outfall flow rate during the storm event
form of the precipitation (rainfall or snowmelt)
Even if your company is capable
of gathering and analyzing the samples, it can be a time-consuming job to track
the weather in order to know when enough dry weather has occurred, when the rain
is going to start, and to document the average or median storm event statistics
for the area. There may be rain in your area, but you end up with a sampling
crew sitting on their hands for several hours, waiting for it to start. Worse
yet, the rain never hits your little corner of the world, you've wasted a whole
shift, and you've got to crank up the troops to do it again at the next threat
The Skywatch Weather Center is
ready to help you. Once you hire us, we track the weather for your location
until we identify a storm event which will satisfy the sampling requirements.
You get notified in enough time to set up for sampling, with details on the
storm's onset and expected duration updated until you get the desired sample. We
also provide documentation on the normal statistics for your area, based upon
data from National Weather Service sites in the vicinity.
All of these features are
available for a fixed rate, based solely on the number of valid samples and
outflow locations you need to characterize. Whether we have to monitor the
weather for a week or a month to get you that sample, it still only costs you
that fixed fee. Discounts are available for:
sampling points at a facility,
all corporate activity nationwide,
sampling scheduled on a year to year basis.
For further information, and to
discuss your specific situation, call our Sales Department at 1-888-818-7250.
*If feasible. Some sites have such light
rainfall events that it might not be possible to get 0.10 inches of
precipitation in a 3 hour period. In another location, the precipitation during
a particular season may be so sporadic that the only episode during the season
must be used, even though it doesn't meet the "should not exceed 50% from
average or median rainfall" criteria.
For more information on the regulations,
check out the EPA Headquarters
A comprehensive presentation of the
standard is available at the EPA
Region 6 website.
The Federal Register listing of the Phase 2
regulations is available at 64
Fed. Reg. 68722.
For more information contact our webmaster
or call us at 1-800-SKYWATC(H) 1-800-759-9282
Copyright © 2005, Air Science Consultants, Inc.