HomeMy WebLinkAbout07.a.1) Update on nutrient studiesCentral Contra Costa Sanitary District
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June 6, 2013
TO: BOARD OF DIRECTORS
FROM: CURTIS W. SWANSON, PROVISIONAL GENERAL MANAGER U�
DANA LAWSON, SENIOR ENGINEER
SUBJECT: UPDATE ON NUTRIENT WATERSHED PERMIT
Overview
The District received an NPDES Permit that became effective April 1, 2012. The term of
the permit is five years. This permit included numeric effluent ammonia limits, and
requirements for the District to study the effects of ammonia discharges on Suisun Bay
and to evaluate alternative treatment technologies for removal of ammonia from its
discharge. The permit also included a reopener clause, whereby the permit conditions
could be modified based on data or results of the required ammonia studies.
Over the past several months, the Regional Water Quality Control Board (RWQCB) has
been advancing a plan for issuing a nutrient watershed permit for the San Francisco
Bay in response to monitoring studies that indicate the resilience of the bay to the
detrimental effects of nutrient enrichment may be weakening.
The Bay Area Clean Water Agencies ( BACWA) has met with the RWQCB staff on
several occasions this year to discuss the proposed nutrient watershed permit, the
nutrient limit setting process and related studies, and timing of a permit. The RWQCB
and BACWA desire to work collaboratively together on the elements of this permit.
Current Nutrient Studies and Engineering Studies
Under the NPDES Permit issued by the RWQCB on February 16, 2012, the District is
required to evaluate the effects of the ammonia, ammonium, and other nutrients in its
wastewater effluent discharge on Suisun Bay. The District developed a Nutrient Work.
Plan in July 2012. The nutrient studies need to be completed by September 2014 and a
report must be submitted to the RWQCB by November 2014. The five elements of the
Work Plan are listed below along with the status (in italics):
1. Participate in the Surface Water Ambient Monitoring Program sampling and
studies related to the Spring Phytoplankton Bloom progression in Suisun Bay.
Status: Sampling complete: only outstanding items are speciation (taxonomy)
work on the study samples and a final paper by the Regional Board and SFCWA.
2. Characterize nutrient forms, concentrations, and loads in the District's effluent
discharge to Suisun Bay. Status: In process — being done by all dischargers.
3. Participate in a collaborative study managed by the State and federal Water
Contractors Agency (SFWCA) of the District's contribution to ammonium
concentrations in Suisun Bay and related toxicity to copepods. Status: To be
done early 2014; may merge this study into the BACWA collaborative studies.
4. Participate in collaborative studies with Bay Area Clean Water Agencies
(BACWA) evaluating the role of ammonia and ammonium in primary productivity
and zooplankton abundance, nutrient ratios, nutrient fate and transport, and the
role of sediment biochemistry in nutrient fluxes. Status: Draft Suisun Bay
Synthesis Report issued November 2012, further studies being planned as part
of Watershed Permit efforts.
5. Determine whether existing sampling locations adequately characterize the
potential impact of the District's effluent discharge to Suisun Bay. Status: Staff
will be obtaining additional Suisun Bay data in the Spring and Fall for use in
further refining modeling efforts to meet this requirement.
The District also developed a Facility & Site Characterization Work Plan in June 2012.
The facility studies need to be completed and a report submitted to the RWQCB by
February 2014. The three elements of the Work Plan are listed below along with the
status (in italics):
1. An Existing Plant Optimization for Ammonia Removal Evaluation to determine
the extent to which ammonia - nitrogen (NH3 -N) removal can be achieved with
relatively modest changes to the existing process and improvement of facilities in
the near -term; in progress, completion expected by August 2013.
2. A Nutrient Removal Facilities Plan to investigate the applicability of both
conventional and emerging innovative technologies for the removal of NH3 -N and
nitrate /nitrite- nitrogen (NO3 -N plus NO2 -N) from the District's wastewater
discharge in the long -term with acceptable generation of greenhouse gases (e.g.
nitrous oxide); in- progress, site visits have been completed and a draft report of
the site visits has been received from HDR, completion expected by November
2013.
3. A Site Characterization Study to evaluate the suitability of property owned or
controlled by the District to provide land necessary for NH3-N and /or NO3 -N plus
NO2 -N removal facilities; Geosyntec has submitted the work plan to the
Department of Toxic Substance Control (DISC) for approval, field work is
expected to occur in July with a final report by August 2013.
Results from the Existing Plant Optimization for Ammonia Removal Evaluation, Nutrient
Removal Facilities Plan, and Site Characterization Study will be presented in the Facility
Plan and Site Characterization Report to be submitted to the RWQCB by February 28,
2014.
Watershed Permit Approach
Since issuing the NPDES Permit to the District in 2012, the RWQCB has been leaning
toward the approach of developing a nutrient watershed permit for the municipal
dischargers to San Francisco Bay rather than handling this issue on a permit -by permit
basis. Municipal wastewater treatment plants account for 50% of the nutrient loadings to
San Francisco bay in the winter and approximately 80% during the summer.
There are several reasons for this changed approach. First is the decreasing resilience
of the bay to the effects of nutrient enrichment. San Francisco Bay and estuary has long
been recognized as a nutrient - enriched estuary. Despite this fact, phytoplankton
biomass in the estuary has been much lower than expected. The low biomass was
thought to be due to strong tidal mixing, low light penetration due to high turbidity, and
grazing by invasive clams. However, since 2005, regional bay monitoring data indicates
an increase in phytoplankton biomass, an increase in chlorophyll -a levels (particularly in
Lower South Bay), an increase in undersirable cyanobacteria (blue green algae) and
their associated toxins, a small decline in dissolved oxygen concentrations, and
decreased water turbidity.
Second, for the past 10 years or so, EPA has been pushing the states to establish
numeric nutrient limits for water bodies including San Francisco Bay. The State Water
Resources Control Board started an effort to create numeric nutrient standards for San
Francisco Bay a few years ago. Nationally, nutrient standards have been established for
highly visible estuaries including Chesapeake Bay and Long Island Sound. From a
District viewpoint, it would be better for the RWQCB to set site specific nutrient limits for
San Francisco Bay rather than having EPA impose a generic national nutrient standard.
Last, the State and Federal Contractors Water Agency ( SFCWA) has focused attention
on ammonia discharges from wastewater agencies by commenting on NPDES Permit
renewals and conducting scientific studies on the detrimental effects of ammonia on
phytoplankton and zooplankton. SFCWA commented on the District's 2012 NPDES
Permit and the 2010 NPDES Permit for Sacramento County Regional Sanitation
District.
Under the collaborative approach that the RWQCB would like to pursue with BACWA
and other stakeholders, multi -year monitoring and scientific studies would be conducted
to obtain data that would be used to develop scientifically -sound nutrient limits for
municipal wastewater treatment plants. Initially, a Nutrient Watershed Permit would
include performance -based nutrient limits or triggers because there is insufficient
information to develop nutrient limits. As scientific information becomes available
through the collaborative science studies, numeric nutrient limits would be developed
and the Watershed Permits would be revised. The RWQCB believes that the
"Watershed Permit process provides dischargers with regulatory consistency and
certainty as well as allows for a careful measured response to phytoplankton biomass
trends, the potential effects of ammonium in Suisun Bay, and harmful algal blooms."
Watershed Permit Components
BACWA and the RWQCB staff are still in the early stages of discussion about such a
permit. However, the RWQCB has made it clear that there will be a nutrient watershed
permit and their goal is for it to become effective April 2014. Tentatively, components of
a nutrient watershed permit will include:
- effluent limitations
- influent & effluent monitoring requirements
- continued support of a regional monitoring program
- triggers for special provisions if harmful or nuisance algae blooms occur
- coordination of Suisun Bay studies
- treatment plant optimization and upgrade evaluations
The RWQCB has indicated that numeric limits will be required for EPA acceptance;
however these would initially be performance -based with the expectation that they
would be adjusted over permit cycles as technical justification is acquired.
Potential Impact for the District
The District's most recent permit includes most of these components already. The
District has a performance -based maximum monthly limit for ammonia, monitoring
influent and effluent, supports regional monitoring programs and is coordinating on
Suisun Bay studies (e.g. Nutrient Work Plan submitted July 2012), and is evaluating the
treatment plant for near -term optimization and long -term upgrades (e.g. Facility & Site
Characterization Work Plan submitted June 2012). A final report for the Nutrient Work
Plan elements will be submitted later this year, and a final report for the Facility & Site
Characterization Work Plan elements will be submitted by February 2014.
The District will actively participate in BACWA and RWQCB discussions regarding the
nutrient watershed permit especially as details are discussed to determine how this may
impact our treatment plant, and the ammonia studies currently underway.
The effect of nutrients on water quality in San Francisco Bay is a complex issue.
Treatment facilities for nitrification to remove ammonia from our discharge could cost up
to $100 million. The cost to remove nitrogen from our effluent would be higher. There
are political, regulatory and economic benefits to the District to deal with the effects of
nutrient discharges on a regional basis through the Watershed Permit process instead
of addressing it alone.
DUCWS