Preview attachment MW NOx mean 3d v2 (1).pdf
MW NOx mean 3d v2 (1).pdf
1.2 MB
by Percy D’Angelo & Rob Robbins
Charlotte County operates four waste treatment plants (WTPs) that use secondary
treatment systems that fail to remove most nutrients such as nitrogen. This means that
the treatment plant effluent that is shipped throughout the county as reclaim water for
irrigation (the purple pipes) has high levels of nitrogen that are discharged back into the
environment. Not surprisingly Charlotte Harbor has a nitrogen problem. Nitrogen feeds
the growth of algae.
The numbers are troubling. Using County test data for reclaim water Rob Robbins and
Percy Angelo have sent analyses to the County showing that the nitrogen discharge in
WTP effluent throughout the County is on the order of 190 tons annually (34.9 mg/L
x1.3 billion gallons of annual discharge) to golf courses, condo associations and
businesses. Unless turf grasses are cut, bagged and removed the nitrogen taken up
by them simply goes back into the environment as the clippings break down.
The West County sewage treatment plants seems to be the least efficient of the County
plants in removing nitrogen. Based on data from the County their effluents are
frequently in the range of 20 to 30 mg/L Total Nitrogen.
The State is aware of the problem of nutrients in reclaim water and a statute requires
that WTPs be upgraded to Advanced Wastewater Treatment (AWT) to discharge no
more than 3mg/L, a level one tenth of the levels currently discharged by the West
County plants. Yet the County currently has no plans to upgrade Rotonda to AWT, and
the upgrade schedule for its other plants is three and more years away.
Besides the delay in improving water quality in Charlotte Harbor this delay in installing
AWT has costly implications for many residents because the County in its Sewer Master
Plan (SMP) has pretended that it needs to solve its water quality problems by requiring
certain communities to convert their septic systems to sewer. Rob Robbins has
researched the technical work underlying the SMP. That work began with a 2013 study
of the East West Spring Lake area. That study involved some 50 monitoring wells
which for the most part showed no problems. The study reports, “Of the 50+ samples
taken during each monitoring period, it is noted that the majority of the wells
demonstrated little to no significant impact.” In fact the majority of samples were below
the limit of detection.
The County utility then hired Brian Lapointe who identified three septic systems which
had failed and were under enforcement action, and tested those. No surprise, he found
high levels of nitrogen at the three cherry picked locations.
Besides the clear error of testing, opposite of random and designed to show problems,
what is also notable is that by the County’s own previous testing of the area it was clear
that those three failed septics did not impact the surrounding groundwater. The
contamination from them had not spread. Aside from the failed septics themselves
somewhat higher nitrogen levels were basically found along US 41 where they were
likely caused by highway stormwater or even leaking sewer lines.
A map showing the test results in graphic fashion is below. The three failed septics are
in purple. The initial 50 or so wells in red. And the height of the columns shows the
relative degree of the nitrogen readings. The lowest levels are so low as to be below
detection.
Lapointe’s decision to study septic by cherry picking the failed ones is like studying a
hurricane to understand the everyday weather. Lapointe’s “inappropriate statistical
methods” in other studies have been criticized by an FDEP scientist in a peer reviewed
study. Yet his work is the basis for the County’s decision in the SMP to require septic to
sewer conversion throughout the county.
This decision has many unfortunate results. Most basically it has caused great expense
and difficulty for many homeowners forced to convert. It has allowed the County to
continue connecting new subdivisions and adding sewage to treatment plants which are
not providing effective treatment, then discharging their effluent back into the
environment as reclaim. Pretending you are providing treatment however does not fool
Mother Nature, which means that when the septic to sewer process is done we still will
not have eliminated the impairments in the Harbor but will have wasted much money
and caused much unnecessary grief.
Sarasota County looked at these very issues and decided to suspend its septic to sewer
process and accelerate conversion to AWT. This is what Charlotte County should do.
Full disclosure, our community of Cape Haze is one of those scheduled for septic to
sewer conversion. We have specifically asked the County if there is any testing
showing problems with septic in our area and have been told there is none. (In fact
groundwater flow for most of West County is toward the west, not toward the Harbor at
all). As far as we can tell the ONLY testing showing problems anywhere in the County
is testing of those three Lapointe wells in East West Spring Lake, testing which showed
only a localized impact and no movement toward the Harbor.
Reclaim water discharge is not the only contribution to Harbor impairments which needs
to be studied. Stormwater in the County is also likely a significant contributor to
nitrogen in the environment as it picks up fertilizer, reclaim and other nitrogen sources
on its way to our Harbor. Stormwater, reclaim, sewer line breaks (frequent in Charlotte)
and failed septic need to all be considered. The current County SMP is obsolete as it
does not even recognize the mandate to install AWT or the possibility of multiple
contamination sources in the Harbor.