Alternative Media Filters
Description
Alternative media filters use filtration media other than
sand, such as peat, compost, activated alumina, or
zeolite to filter out, or strain, particles and
particle-bound constituents found in stormwater.
Stormwater pollutants are removed through physical,
chemical, and biological processes, including
filtration, adsorption, microbial activity, and
decomposition. Common constituents that are removed
include total suspended solids (TSS), total phosphorus,
total metals, microbiological constituents, and litter,
but alternative media filters can also have the
potential to remove dissolved constituents such as
metals, nutrients, and trace organics (which sand
filters do not remove particularly well).
Experience
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Kristar Perk Filter™
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The Kristar Perk Filter™ Study is a laboratory
evaluation of the hydraulic and treatment
performance of a proprietary canister filter
BMP. Clean water was used to estimate hydraulic
capacity at different water depths up to bypass
conditions. Pollutant removal was estimated by
measuring the water quality before and after
loading the filters with synthetic stormwater.
Both ground silica and street dust were used as
a sediment source.
OWP Tasks
- Developed Study Plan
- Conducted Laboratory Experiments
- Analyzed Data
- Provided Consultation for Product
Development
- Prepared Reports
-
Caltrans Tahoe Basin Small-Scale Pilot
Studies – Alternative Media Filters
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The Caltrans Tahoe Basin Stormwater Pilot
Program consists of both small-scale and
full-scale pilot studies. Small-scale
alternative media filter columns were
constructed and operated intermittently to treat
discrete batches of stormwater collected from
various runoff events. Filters that use media
other than sand have the potential to remove
dissolved constituents such as nutrients,
metals, and trace organics that are not removed
particularly well by sand. The primary objective
of this study was to determine the expected
performance of alternative media filters in
removing turbidity and nutrients from Tahoe
stormwater runoff. As well as determining the
performance of various alternative media (e.g.,
activated alumina, limestone, iron oxide), this
study evaluated the effect of chemical addition
and the hydraulic benefits of fabric
prefiltration and graded media.
OWP Tasks
- Assisted in Study Planning
- Reviewed Experimental Designs and
Methods
- Provided Technical Assistance
- Assessed Study Results
- Reviewed Study Reports and
Recommendations
-
Caltrans Tahoe Basin Full-Scale Pilot
Studies – Alternative Media Filters
-
As part of the Caltrans Tahoe Basin Stormwater
Pilot Program, six full-scale Austin-type
filters and two small footprint vault filters
were designed, constructed, and monitored on Hwy
50 and SR 267. These alternative media filters
utilized activated alumina, iron-modified
activated alumina, or limestone media. Filters
that use media other than sand have the
potential to remove dissolved constituents such
as nutrients, metals, and trace organics that
are not removed particularly well by sand. The
objectives of these studies were to determine
the effectiveness of alternative media filters
in removing fine particles, turbidity, and
nutrients; hydraulic performance of the filters
in the alpine climate; maintenance requirements;
and construction and maintenance costs. These
data were compared to regulatory effluent
limits, and load removal assessments were made
to compare with expected requirements in the
Lake Tahoe TMDL.
OWP Tasks
- Assisted in Study Planning
- Reviewed Designs of Monitoring
Systems
- Provided Technical Assistance During
Design, Construction, and Monitoring
- Assessed Study Results
-
Caltrans Compost Stormwater Filter
System
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The CSF System Study was a two-year study
conducted in Orange County along State Route 73.
The primary objective was to assess the
effectiveness of the existing stormwater Best
Management Practices (BMPs)—the CSF Systems.
Other objectives included assessing the quality
of runoff from State Route 73, assessing if the
CSF Systems were exporting nutrients, and
assessing if exporting nutrients were resulting
in the impairment of water quality and
beneficial uses. For each of three sites,
influent and effluent water quality samples were
collected and compared. Visual inspections of
the receiving waters assessed whether
eutrophication was occurring.
OWP Tasks
- Assisted in Study Planning
- Provided Monitoring Assistance
- Reviewed Data Assessment and
Reporting
-
Kristar TreePod® Filter
-
The Kristar TreePod® study was a laboratory
evaluation of the hydraulic and pollutant
reduction performance of a non-proprietary,
modular bioretention BMP for stormwater
treatment. Clean water was used to estimate
hydraulic capacity at different water depths up
to bypass conditions. Pollutant removal was
estimated by measuring the water quality of the
influent and effluent of the filter.
Representative influent concentrations were
achieved by using street dust that was collected
from street sweepers and sieved to exclude
particles larger than 75 microns.
OWP Tasks
- Developed Study Plan
- Conducted Laboratory Experiments
- Analyzed Data
- Provided Consultation for Product
Development
- Prepared Reports
