Cudjoe Regional Wastewater
Treatment System
Let’s Finish the Job Well
Wastewater injected in shallow wells moves to surface waters
Florida Keys National Marine Sanctuary Water Quality Protection Program
2013 Report to Congress (pg. 22)
“Wastewater
disposed into a
shallow injection well
can rise toward the
surface and
contaminate
residential canals and
other near- shore
waters as shown in
this experiment using
viral particles as
tracers (Paul 1997).”
Wastewater injected in shallow wells moves to surface waters
“Groundwater movement in the Florida Keys
is quite different than most coastal systems.
Groundwater and surface waters continuously
interact due to the porous nature of the water
table aquifer. “
“When tides are high in the Atlantic,
Atlantic surface water is pushed into the
subsurface and groundwater flows toward
Florida Bay. When tides are low,
groundwater flows toward the ocean. This
continual sloshing of groundwater controls
the overall path of the injected wastewater
and septic effluent in the subsurface, thus
increasing the possibility of surface water
contamination.”
“Submarine Groundwater Discharge, An Unseen
Yet Potentially Important Coastal Phenomenon”,
Corbett, Burnett, Chanton (National Sea Grant
College Program of NOAA) at page 5.
Wastewater injected in shallow wells moves to surface waters
“After injection into a well, the less dense buoyant wastewater
plume rises toward the surface.”
CRWWTP is
sited at a closed
landfill
“Results demonstrated that wastewater is rapidly transported upward
toward the surface and laterally, which delivers tracers placed into
injection wells to nearby surface waters after several days to weeks…”
Kevin Dillon, Gulf Coast Research Laboratory, Ocean Springs, Mississippi Tropical
Connections, page 143 (2012)
Lower Keys Waters Require Very Low Nutrient Levels
“The Florida Keys coral and seagrass
communities are dependent on very low
nutrient conditions. Any increases in nutrient
loading results in the beginning of changes in
the biotic community and can ultimately
result in green water (high chlorophyll)
and/or smothering of hard bottom
communities by benthic algae.”
William L. Kruczynski, Ph.D. Retired EPA Scientist
Florida Law acknowledges the unique geology and
fragile waters of the FKNMS
Chapter 99-395 Laws of Florida
Sec. 6. Sewage Disposal Requirements for Monroe County
• Legislature finds that the discharge of domestic
wastewater compromises the quality of the coastal
environment of the Florida Keys
• Reflects DEP’s finding that excessive nutrients constitute
one the of the most severe water quality problems facing
the State. Particular attention should be given to protect
those waters presently containing very low
nutrient concentrations.
Minimum Disposal Requirement: Provide reasonable
assurance of no harm to surface waters
If Design Capacity is 1 mgd or more:
• Deep well is mandatory
If Design Capacity is under 1 mgd:
• … “ wells designed to inject domestic wastewater in Monroe
County shall be required as part of the operation permit
application to provide reasonable assurance that operation of
the well will not cause or contribute to a violation of surface
waters standards” 6-528-630(7) F.A.C.
• …DEP shall order the point or method of discharge changed
“if it is demonstrated that a discharge, even if …otherwise in
compliance…, will cause or contribute to a violation of state
water quality standards…” FS. 403-086(10)(h)
Deep Well and 1 MGD: It is all about the Money
Monroe County Sanitary Master Plan (2000) .
“Deep well injection is
mandated in Monroe County
for effluent discharged from
plants of 1 mgd capacity and
greater. Because deep well
injection eliminates all
wastewater nutrients from
the environment, deep well
injection was also evaluated
for the 0.5 mgd plant size but
was found to be more
expensive than shallow well
injection.” Pg 3-22.
(width of wells not to scale)
AWT leaves nutrients in the water far in excess of
DEP Water Quality Standards for Lower Keys.
“The total nitrogen (TN) and total phosphorus levels in the back country
waters nearby are already too high… The addition of any further TN and
TP loads will contribute to violation of numerical nutrient standards
recently adopted by DEP.” Brian Lapointe, Ph.D. June 12, 2014
DEP’s Water Quality Standards for the Lower Keys
vs. AWT Nutrient Levels
7
6.00
6
MG / L
5
Phosphorous
4
3.00
3
2.00
2
1
Nitrogen
1.00
0.21
0.008
0
DEP WATER
QUALITY
STANDARDS
CRWS Permit
Limits: Annual
Average
CRWS Permit
Limits: Single
Sample
TOTAL PHOSPHOROUS MG/L
DEP WATER
QUALITY
STANDARDS
CRWS Permit
Limits: Annual
Average
CRWS Permit
Limits: Single
Sample
TOTAL NITROGEN MG/L
Although AWT will result in a net reduction of nutrients from
the FKNMS as a whole …
…the regional concentration will harm local waters.
RAMP-UP FLOW PROJECTIONS (MGD)
2.50
2.35
1.99
2.00
1.50
1.00
1.44
1.18
1.07
.94
1.00
.89
.72 .80
.58
0.50
0.00
2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Design
Year
2028
AADF
TMADF
Maximum Month
Peak Day
Even relatively
small levels of
discharge
during the
expected ramp
up period …
can impact the
surface waters
of the Cudjoe
Basin. Brian
Lapoint, Ph.D.
RAMP-UP FLOW PROJECTIONS (MGD)
2.50
2.35
2.26
2.20 2.21 2.22 2.24 2.25
1.99
2.00
1.44
1.50
1.10 1.11 1.11 1.12 1.12 1.13
1.00
1.00
0.89
0.72
0.91
0.66 0.80
0.50
0.45
0.35
0.41
1.00 1.01 1.01 1.02 1.02 1.03
0.88 0.89 0.89 0.89 0.90 0.90
1.18
1.07
0.94
0.58
0.17 0.36
0.16
0.00 0.14
2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Design
Year
2028
AADF
TMADF
Maximum Month
Peak Day
Even relatively
small levels of
discharge
during the
expected ramp
up period … can
impact the
surface waters
of the Cudjoe
Basin. Brian
Lapointe, Ph. D.
Cudjoe Regional Wastewater
Treatment System
Let’s Finish the Job Well