BMP Monitoring Sites - Urban Drainage and Flood Control District

UDFCD BMP MONITORING SITES
Pervious Concrete Pavement
AASHTO #67 and the west pad used AASHTO #8. Below the surface, there
are two lateral flow barriers in the form of concrete walls. At each barrier, the
filtered water is collected in perforated pipes and carried to a manhole located
adjacent to the pervious concrete pavement. Inside the manhole a riser pipe with
an orifice is sized to drain the entire gravel pore volume of each cell
in 6 hours or more. A riser pipe with a levelogger is located just upstream of
each manhole to measure the flow coming from each cell. All flows from the
pervious concrete pavement are combined and discharge east of the site through
a V-notched weir where a pressure transducer measures the depth of flow
and sends the data into the sampler.
Adjacent to the pervious concrete pavement watershed is a control
watershed of traditional asphalt pavement used to compare results of treated
runoff to untreated, direct runoff. Stormwater runoff from the control watershed is
collected in a sump catch basin at the northeast corner of the site. Water is
conveyed a short distance to the outfall and flows through an H-flume where
flow is measured by a pressure transducer.
The sampling equipment is stored in a shed near the outlet works. A rain gage
on top of the shed measures rainfall and signals the ISCO samplers inside the
shed to begin sampling after 0.1 inches of rain falls. The samplers then draw a
sample of water from both the pervious concrete pavement runoff and the control
runoff after ??? cfs has passed, and then every 15 minutes until 12 hours after
the storm has ended.