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

1.  2006 LTBMU Urban Stormwater BMP Effectiveness Monitoring Synthesis
    Report -- Nicole Beck

2.  Cultured Ecology Pilot Test Results -- Steven Patterson

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

**2006 LTBMU Urban Stormwater BMP Effectiveness Monitoring Synthesis
Report** -- Nicole Beck

Catherine introduced Nicole with a statement from the Forest Service
listing the intended purposes of the BMP effectiveness monitoring
synthesis and acknowledging that Nicole was put in the awkward position
of evaluating the work of her peers without the anonymity common to peer
views. The purposes of the synthesis of BMP effectiveness data (from FS
Comprehensive Urban Runoff Treatment Effectiveness Monitoring (CURTEM)
projects and a few CTC monitoring projects) was to make more accessible
the BMP effectiveness results, and the lessons learned from BMP
effectiveness monitoring to improve project implementation and future
BMP effectiveness monitoring. While there was little new data to fill in
the gaps about BMP effectiveness for the Tahoe TMDL, the FS is hopeful
that the recommendation in the report will be used to improve future BMP
effectiveness monitoring and reporting.

Nicole described the process by which the synthesis was performed
including the utilization of a standard review form (included as
Appendix A in the report) for the preliminary review of BMP
effectiveness monitoring reports, subsequent interviews with principle
investigators, data analysis, and report synopses. The standard review
form is separated into sections to evaluate the quality of the study
objectives and design, data collection approach and consistency, report
presentation, and conclusion and recommendations. Due to the variation
and inconsistencies in data collection and analysis between reports, the
Nomenclature of Pollutants section in Nicole's synthesis report
recommends particular species for analysis of nitrogen, phosphorus, and
sediment based on analytical procedures and common practices.

The three types of BMPs monitored for effectiveness in the reports
reviewed were dry detention basins, wet basins, and mechanical treatment
structures. Tables were developed to show the useful and recommended
meta data that should be collected for each of these BMP types to
improve comparability of monitoring data and results, and the degree to
which each report contained the recommended data. In addition to the
effectiveness data that it is typically collected for all BMP types like
event mean concentrations (EMCs) for inflow, outflow, and percent
removal for target pollutants, additional meta data for basins should
include flow path length, hydraulic residence time, depth to ground
water, and vegetation characteristics. In general, basins provide good
reductions in Total Suspended Solids (TSS), but are typically limited in
removing dissolved nutrients (best outflow concentrations for NO~x~ ≥
250 μg/L, SRP ≥ 50 μg/L). Nicole found that basin monitoring was
typically weak in relation to assessing the impacts to ground water
(because it was usually limited to surface water monitoring) and that
100% retention was considered 100% treatment. Nicole also found that
EMCs were determined by three different methods depending on the data
collected and that the various methods did not always produce consistent
results. It is recommended that sediment monitoring, which has been
typically limited to just TSS, should begin to include particle size
monitoring in response to the finding that fine sediments are
responsible for up to 65% of the lost of clarity in Lake Tahoe. The
monitoring of mechanical treatment improvements (various commercial
vaults and filters, and sediment traps) could be improved by determining
the cost benefit in terms of sediment removed, and the impacts of
maintenance on effectiveness. There were a few other CURTEM reports that
were reviewed in the synthesis effort that did not fall within the three
BMP types; one on source control which contains good advice for
utilizing cost effective parameters for monitoring improvements, and a
few others on chemically enhanced BMPs for removing nutrients and
sediment which raise concerns about the potential ecological impacts of
coagulants and flocculants.

The lessons learned for more effective monitoring and implementation of
BMPs are contained in Nicole's recommendations for managers,
implementers, and researchers. The recommendations include performing
longer term high-resolution monitoring, development of monitoring plans,
technical review of monitoring plan design and results reports,
development of rapid assessment methodologies that can be linked to high
resolution findings, make monitoring data more accessible, development
of clearer BMP and monitoring objectives, and build on existing
knowledge from monitoring and research. The report recommends monitoring
BMPs for continuous hydrology and performing water balances to better
ascertain the how the BMPs are operating. The report also recommends
additional analysis of the raw BMP effectiveness monitoring data to
develop more consistent results for better comparability and the
development of a quantitative database for all BMP effectiveness meta
data as an adaptive management and TMDL tool.

The 2006 LTBMU Urban Stormwater BMP Effectiveness Monitoring Synthesis
Report can be found on the LTBMU's publications ftp site at:
<http://www.fs.fed.us/r5/ltbmu/publications/>, and Nicole Beck can be
contacted at: [nbeck@2ndnatureinc.com](../nbeck@2ndnatureinc.com).

**Cultured Ecology Pilot Test Results** -- Steven Patterson

Steven presented the results of a pilot scale study of the use of
cultured periphyton to treat stormwater runoff for fine sediment and
dissolved nutrients. This project was funded by the USEPA through the
Nevada Tahoe Conservation District, and Steve was assisted by the Tahoe
Environmental Research Center and the Desert Research Institute. This
technology is being developed as a potential advance treatment of
stormwater runoff to provide the 30 to 40 % pollutant load reductions
proposed in the Lake Tahoe Clarity technical TMDL. Periphyton is an
assemblage of algae, cyanobacteria, diatoms, bacteria, and other
organisms that grow under water attached to submerged surfaces.
Periphyton exists as a mucilaginous matrix that captures fine sediments,
and consumes dissolved nutrients directly from the water column even at
low concentration and temperatures given enough light. The idea for
applying this technology in the Tahoe Basin came from observations of
the effectiveness of wet basins. The periphyton used in this study was
collected from natural and man made sources within Lake Tahoe and the
Basin.

The pilot scale study set-up consisted of two above ground, 150 gallon,
translucent-walled culture tanks in series followed by a 300 gallon
culture trough. The culture tanks each contained a PVC frame for a
cylindrical screen of fabric which acts as the substrate for the
attached growth of periphyton. The tank walls allowed transmission of
80% of visible light, and light transmission was enhanced by selecting
tanks that are taller than they are wide, and by installing a reflective
metal plate north of the tanks. For maximum periphyton productivity
(based on coral reef observations), a turbulent flow regime was
established within the culture tanks with a submerged air pump that
accumulates air until periodic releases. The cultured trough was modeled
after a floating wetland, but it did not provide any additional
treatment benefit to the effluent from the culture tanks and will likely
be moved to before the cultured tanks in future applications.

The pilot test monitoring consisted of collecting data related to the
periphyton harvest (biomass analysis), synthetic stormwater treatment
tests, and base flow water chemistry. Treating only a spring fed base
flow for four months, and harvesting the periphyton every 30 days, the
culture tanks were able to remove a total of 3.6 grams of phosphorus per
square meter of tank footprint (g P/m^2^), which is the basis of the
estimate that cultured periphyton can remove 10 g P/m^2^/yr. Turbidity
was consistently reduced to 13 NTU in the effluent from influent
concentrations ranging from 135 to 53 NTU. Fifty percent of the
particles removed were 11 μm or less in diameter. Nitrate concentrations
were consistently reduced to 3 μg/L in the effluent from influent
concentrations that ranged from 81 to 10 3 μg/L. Phosphorus removal
appeared to be nitrogen limited and influent concentrations ranging from
42 to 64 μg/L were reduced to a range of concentrations from 22 to 46
μg/L in the effluent.

The synthetic stormwater treatment tests were set up in two different
configurations. The first synthetic stormwater treatment test was set up
with the synthetic stormwater delivered directly from a 1000 gallon tank
with a mixer to the treatment train of the two culture tanks and one
culture trough. In the second test a pretreating fore bay was modeled by
first cycling the synthetic stormwater through a 300 gallon settling
trough, then cycling the pretreated synthetic stormwater through the two
culture tanks and one culture trough treatment train. The synthetic
stormwater was created with 2 kg of road sweepings, had a 5 in secchi
depth reading, and a turbidity of135 NTUs. The particle size
distribution was relatively unchanged by treatment. Since the culture
tanks must remain wetted, the initial volume of base flow resulted in
dilution of the synthetic concentrations. Cycling in the second test
allowed for determining the maximum treatment levels, or lowest
pollutant concentrations achievable. Again phosphorus treatment removal
was limited by low nitrogen levels and enhanced by higher nitrogen
levels, which suggests that a nitrogen and possibly carbon feed may
provide for greater phosphorus and nitrogen removal.

Extrapolating from the results of the pilot system: 8 tanks could treat
a 5000 cubic feet of storm volume over a 3 day period, and 35% of 50
million tons of phosphorus could be removed in a treatment area of 175
ha (432 acres). Future considerations for improving stormwater treatment
effectiveness by cultured periphyton and developing applications of this
technology include investigating methods of periphyton removal,
potential uses of harvested periphyton, and opportunities to test and
fund a second generation design. Steven Patterson can be contacted at:
916-524-9039 or [<spatterson5000@earthlink.net>.]{.underline}

In Attendance:

Scott Brown, NTCD\*

Scott Carrol, CTC\*

Jason Drew, NCE

Mike Elam, TRPA\*

Cynthia Gillis, CSLT

Jena Green, USGS

Steve Goldman, CTC\*

Alan Heyvaert, DRI

Lisa Huffman, MACTEC

Gretchen Huie, NTCD

Sarah Hussong Johnson, CSLT

Christine Kirick, Wood Rodgers\*

Jason Kuchnicki, NDEP\*

Theresa Loupe, USFS

Steven Patterson, BioxDesign

Joe Pepi, CTC

Ginger Peppard, WET Lab

Karin Peternel, Kennedy/Jenks

Michael Pook, NTCD

Chad Praul, Environmental Incentives

Jennifer Quickel, CSLT

Jeanne Riley, CDM

Dave Rios, NTCD\*

Catherine Schoen, USFS\*

Mark Sedlock, CTC\*

Andy Smith, WET Lab

Matt Vitale, NTCD\*

Rita Whitney, TRPA\*

Next Agenda\*: