Low Impact Development Manual for Michigan - OSEH - University ...

Case Study: Constructed Linear Sand Filter
City of Wayne, MI
This BMP is a two-chambered linear concrete structure that improves water
quality by providing sedimentation and filtration to the stormwater runoff.
The site for this BMP serves a 0.9 acre parking lot at two senior citizen
housing complexes in the City of Wayne, Michigan. The drainage area to
the filter is approximately 0.8 acres. This filter inflow is a sheet flow from
the parking lot through a linear steel grating.
The filter consists of two chambers. The first chamber is a sedimentation
chamber, and the second is the filtration chamber. Runoff enters the filter
structure through grates located in the parking lot next to an existing curb.
The runoff overflows the weir between the two chambers and passes through
an 18-inch sand filtration layer and a four- inch gravel drain bed. A fourinch
perforated collector pipe runs along the length of the gravel layer to
collect the filtered runoff. Geotechnical filter fabric is installed between the
sand and the gravel layers. There is a clearwell chamber in the downstream
side of the structure to capture the filtered runoff from the perforated pipe
and the overflow runoff from the filter overflow weir.
The available depth of storage volume above the filtering material on this
site is 1.8 feet. The width of the two chambers was fixed at 2 feet each. The
design filtering material permeability is 3.5 ft/day. The maintenance of the
filter includes cleaning the filtering material, and possibly replaced, if the
treatment rate of the filter media becomes unacceptable due to clogging. In
addition, the sedimentation chamber must be cleaned as required depending
on the volume of sediments in the chamber.
Sand filter in the City of Wayne, MI
Source: Wayne County Department of Environment
Project Type Constructed filter
Estimated Total
Project Cost
Maintenance
Responsibility
Case Study Site Considerations
$10,000
Wayne County
Project Contact Razik Alsaigh, 313-967-2283
Applicability of sand filters in
the Rouge River Watershed is
considered to be substantial.
Sand filters could be installed
in fully-developed areas in
which land for more conventional
and less expensive
BMPs is unavailable. Example
locations could include small
convenience stores, industrial
sites, small tributaries to lakes,
and other identified problem
areas.
LID Manual for Michigan – Chapter 7 Page 158