BMP Monitoring Sites - Urban Drainage and Flood Control District

UDFCD BMP MONITORING SITES
Permeable Interlocking Concrete Pavement
gravel and C-33 sand. In a trench beneath the sand, a perforated
pipe collects the filtered water and conveys it to a catch basin.
There is an orifice plate at the end of the pipe where a pressure
transducer measures the flow into the catch basin from the PICP.
There is also a weir plate at the outlet of the catch basin with a
levelogger that measures the flow leaving the catch basin. The difference
between the flow passing the orifice plate and the flow passing the weir
plate is equal to the runoff that bypassed the PICP and entered the
catch basin through the grate.
The sampling equipment is stored in a metal box in the island adjacent
to the PICP. A rain gage on a post near the storage box measures
rainfall and signals the ISCO sampler inside the box to begin sampling
after 0.1 inches of rain falls. The sampler then draws a sample of water
from the PICP runoff after a designated flow has passed, and then
every 15 minutes until 12 hours after the storm has ended.
There is also a control watershed located a few hundred feet northeast of the
PICP watershed. The control watershed consists primarily of traditional asphalt
pavement and is used to compare results of treated runoff to untreated, direct
runoff. Stormwater runoff from the control watershed is collected in a grated
catch basin located in the northeast corner of the parking lot. The water leaves
the catch basin by passing through a weir plate where a pressure transducer
measures the flow. The sampling equipment is stored
in a metal box adjacent to the parking lot in a manner
similar to the PICP sampling configuration.