**[Topic List:]{.underline}**

1.  Caltrans Media Filter Pilot Studies in the Tahoe Basin - Mark
    Keisler, Dipen Patel, and Stefan Schuster

2.  Apalachee Phase 1 -- Nottaway Basin Treatment Train Effectiveness
    Monitoring - Alfred Knotts

**[Topic Summary:]{.underline}**

**Caltrans Media Filter Pilot Studies in the Tahoe Basin** - Mark
Keisler, Dipen Patel, and Stefan Schuster

Two full scale pilot infiltration basins with activated alumina media
filters were installed along US50 adjacent to the airport. One basin was
sized with a surface area 3% of the treated road surface. The second was
sized to 1% of the treated road surface to allow higher loading of the
filter and better prediction of media life. Each basin has automated
samplers at the inflow and outflow locations. At least 28 events were
sampled at each of the four sampling sites over the past 3 years and
several constituents were measured with the goal of meeting LRWQCB
surface discharge effluent limits. Overall, the reduction in turbidity,
TSS, and total phosphorus (TP) was about 80% although only TP met the
LRWQCB limits. Total Nitrogen (TN) was reduced approximately 50% at both
sites and one of the sites met the LRWQCB limit.

The test highlighted a couple of interesting issues. First, events
immediately after installation generated elevated pH and concentrations
of dissolved aluminum, however, as the basin aged the pH and
concentrations were more in line with expectations. One of the basins
developed a ½ inch layer of fine sediment on top of the filter surface
which limited flow through the treatment area and ultimately required
removal. The sediment layer was attributed to a nearly constant
groundwater flow intercepted by the conveyance system between the basin
and the road way.

Monitoring of the site was challenging for several reasons. Snow and ice
build up would prevent normal flow of precipitation events resulting in
a large effluent flow after a thaw. Sampling of a single rain or melt
event could be difficult because the event may be multi-phase. Finally,
it was difficult to isolate one event from another if the previous event
had not fully infiltrated.

Cost to construct each site was approximately \$300k, activated alumina
\$30k (but recently doubled or tripled in cost), and maintenance was
approximately \$150k per site per year.

**Apalachee Phase 1 -- Nottaway Basin Treatment Train Effectiveness
Monitoring**

\- Alfred Knotts

As part of the Apalachee Phase 1 effort, a treatment system was
installed in 2005 at the end of Nottaway Drive that includes a
pretreatment vault with oil baffles, a detention pond, and sand filter.
The event monitoring program is just beginning and only preliminary test
data was presented.

The presentation (attached) has extensive narrative in the slides, but a
couple of things should be emphasized.

\- For non-overflow events, the sequence of water through the treatment
system is to the pre-treatment vault, basin, sand filter, then to the
effluent (see slide 26).

\- The basin is designed to drain within 72 hours for vector control
reasons.

\- The monitoring of the new system has just begun.

In Attendance:

Scott Brown, NTCD\*

Scott Carrol, CTC\*

Scott Cecchi, CTC

Jeff Curtis, ECO:LOGIC

Mike Elam, TRPA\*

Chris Ennes, NDOT

Ellery Foster, TRPA

Eric Friedlander, Avalex Inc.

Cynthia Gillis, CSLT\*

Steve Goldman, CTC\*

Kim Gorman, Lahontan RWQCB

Earl Hagadorn, Private consultant

Elizabeth Harrison, NDSL

Lisa Huffman, MACTEC\*

Mark Keisler, CalTrans

Alfred Knotts, EDOT

Jason Kuchnicki, NDEP\*

Nova Lance-Seghi, Placer Co.

Errik Larson, TRPA

Theresa Loupe, USFS\*

Kansas McGahan, Placer Co.

Charlie Miller, Entrix

Derek Norpchen, TRPA

Dipen Patel, CSUS - OWP

Dave Rios, NTCD\*

Steve Rodriguez, Lumos

Tim Rowe, USGS-WRD

Catherine Schoen, USFS\*

Jessica Schwing, TRPA

Mark Sedlock, CTC\*

Andy Smith, WET Lab\*

Penny Stewart, CTC

Chris Twomey, c2me

Matt Vitale, NTCD\*

Rita Whitney, TRPA\*

Russ Wigart, CTC

Next Agenda\*: