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determination of groundwater-flow direction and rate beneath florida bay, the florida keys, and reef tract >
1998 proposal
Project Proposal for 1998
Program: FRAGILE ENVIRONMENTS
Project Title:
Determination of Groundwater-Flow Direction and Rate Beneath Florida Bay, the Florida Keys and Reef Tract
Location of Study Area: Florida Bay and Reef Tract
Project Start Date: FY 1996
Project End Date: FY 1999
Project Number: 7242-37654
Project Chief: E. A. Shinn
Region/Division/Team/Section: Eastern/Geologic/Marine and Coastal/St.
Petersburg
E-mail:
eshinn@usgs.gov
Phone: (813) 893-3100 ext. 3030
Fax: (813) 893-3333
Mailing Address: 600 4th St. S, St. Petersburg, FL 33701
Program Element(s)/Task(s) Element 1. Task 1.6
Panel:
Collaborators, Clients:
Army Core of Engineers
Our results and ongoing monitoring activities should provide additional
means of
determining, the effectiveness of "replumbing" the everglades.
South Florida Water Management, Florida Marine Research Institute and
University of South Florida, Florida State University and University of
Miami
Department of Environmental Protection
Data provided by this study has been used by this department and is
expected to be
used in the future.
National Park Service
The park service is interested in the delivery of nutrients from below,
especially
from the so-called "river of sand."
Other Environmental Organizations and Businesses
The results of this study will have a profound impact on future development
and
tourism in the Florida Keys
Project Summary:
Treated sewage is injected into the
limestone under the Florida Keys via on-site disposal systems (OSDs). There
are 25,000 septic
tank systems, approximately 5,000 cesspools, and approximately 1,000 class
5 injection wells.
Depth of injection wells ranges from 10 to 30 m. Excessive algal growth,
coral diseases and both
marine grass and sponge mortality is perceived by the local population,
NOAA, and EPA, to be
caused by sewage nutrients leaking from groundwater on both sides of the
Florida Keys.
Determining the rate and direction of saline groundwater movement beneath
the Keys and Florida
bay is considered critical to understanding the fate and effects of
subsurface waste water
disposal in the Florida Keys.
Project Justification:
Management issues: As a result of this and related work, the state of
Florida (in 1996)
modified rules for installation of class 5 disposal wells. In addition, the
EPA, citing our earlier
work, has issued a warning statement to the State of Florida Department of
Environmental
Protection stating that "the geology of the Florida Keys is unsuitable for
class 5 disposal wells."
Reliable data on the flow direction and rate of groundwater movement in the
Florida Keys as well
as contamination levels is vitally needed.
Clients include State of Florida
DEP, EPA, NOAA (this
is a NOAA Sanctuary) ENP, and Monroe County. Monroe County is planning a
multi-billion dollar
sewage disposal system and is has been following our work very closely. The
PI meets regularly
with Monroe county and NOAA Sanctuary management and serves on the
Technical Advisory
Panel (TAP) for the Florida Keys Marine Sanctuary Water Quality Advisory
Committee.
Project Objectives:
The objectives of this research are to determine the rate, direction of
flow and
contamination levels of saline groundwater in the Florida Keys and Florida
Bay. Contamination
studies are necessary to determine if nutrient and other contaminant
levels are rising, and to
provide a baseline of data for future decision making.
Overall Strategy, Study Design, and Planned Major Products:
The strategy of this study is to use artificial tracers to determine rate
and direction of
flow. Tracers are injected into well clusters, existing sewage treatment
facilities, and
sewage disposal wells. In addition to tracer studies groundwaters will be
collected for
contamination analysis so as to provide a base-line against which the
effects of population
increase and success of future wastewater treatment facilities can be
evaluated in the future.
Overall:
Seventy eight submarine monitoring wells have been installed in the Florida
Keys
reef tract, Florida Bay and Shark river slough and an additional 14 were
installed in
Biscayne bay in conjunction with a Miami WRD modeling, study. Six
additional multi-
depth wells were installed onshore at the Keys Marine Laboratory bringing
the total
number of wells to 84. All wells were continuously cored and cores reside
at the St.
Petersburg Coastal Center. Twenty of the 84 wells were installed to form
two (200 ft
diameter) circular clusters, each with an injection well in the center. The
clusters, located on
opposite sides of Key Largo, were designed to determine groundwater flow
direction and
rate. Each is screened at two depths, (-20 and -45 ft). The following tests
have been
conducted using the well clusters: 1) three separate dye tracer tests using
fluorescein and
Rhodamine, 2) one test using a colaphage (done in conjunction with
University of South
Florida) and 3) a single test with Sulfur Hexafluoride (SF6) as the tracer.
The first two sets
of tests determined flow direction and provided sufficient information to
"zero-in" on the
actual flow rate. An additional well (100 ft from cluster) was added to
each cluster once the
direction of movement was determined. The third test (using a combination
of dyes and
SF6) provided accurate flow-rate estimates. This data facilitates the
design of future rate
and direction experiments.
Additional monitoring wells will be installed (approximately 20 wells at 10
sites) to
evaluate the "river of sand" hypothesis. These wells will be drilled in
central, northern and
western Florida Bay in the vicinity of Flamingo. Waters will be collected
for chemical
analysis to determine if contaminated waters are entering the bay from
below, (i.e. the deep
Floridan aquifer or shallow Biscayne aquifer) If water levels permit, we
will also install a
series of wells in the Taylor slough area of the southern Everglades. These
wells will
support another related fragile environments projects.
The overall future direction of this project is shifting toward nutrient
and contaminant
monitoring and evaluation of the "river of sand" hypothesis. Water samples
will
be collected biannually for the remainder of the study.
Timeline:
1997
1. Install 20 to 25 additional monitoring wells.
2. Conduct additional tracer studies using both well clusters and
existing (working disposal wells).
3.Sample wells for chemical analyses.
1998
1 . Continue tracer studies.
2. Sample wells biannually for nutrient and other chemical analyses.
3. Drill additional wells as needed.
4. Model cross keys ground water flow and tidal pumping using visual
mod flow.
5. Begin synthesis of results (Shinn, Reich Hickey and Tihanaky)
1999
1. Sample wells biannually
2. Complete synthesis of results
3. Produce several publications
Planned Deliverables/Products:
Papers will be given orally at national annual meetings (One was given at
GSA in
1995 and at AAPG in 1997. A methods paper by Reich has been published.
Final products
(report) will be delivered to various clients including State of Florida
Department of
Environmental Protection, Federal EPA , NOAA, (Florida Keys National Marine
Sanctuary) Everglades National Park, and Monroe County planning department.
Planned Outreach Activities:
Ongoing outreach activities have already made this one of the most highly
visible
projects in south Florida. These outreach efforts will continue. Highlights
of the study
appear in a video USGS outreach video, and in "The Geology of Florida"
produced by the
State Geological Survey. Highlights of the study have also appeared on PBS
television
special, "The Aquarius Habitat."
Prior Accomplishments in Proposed Area of Work:
New Directions, Expansion of Continuing Project (if applicable):
Accomplishments and Outcomes, Including Outreach:
Tracer tests in the well clusters have shown: 1) tidal pumping and higher
sea level
in Florida bay is the major force driving groundwater movement, 2)
groundwater
movement is primarily perpendicular to the Florida Keys thus major flow is
towards the
east and the reef tract (there is also flow toward Florida Bay), 3) the
maximum rate of flow
(towards the east) is 3.5 m/day. (approximately 100 m/month or 1 km/year).
Collaborative studies with USGS Reston based VIRD research group using CFCs
and Oxygen and Hydrogen isotopic data support limited movement of Florida
Bay
groundwater into the inner reef tract east of Key Largo.
This study has already led to modifications of State regulations for
installation of
sewage disposal wells. Because of our work the EPA has determined that "the
geology of
the Florida Keys is not suitable for the use of waste disposal wells."
Highlights of the study appear in a video USGS outreach video, and in "The
Geology of Florida" produced by the State Geological Survey. Highlights
of the study
have also appeared on PBS television special, "The Aquarius Habitat." )
Deliverables, Products Completed:
Shinn E. A., Reich C. D., Hickey, D. T., Bohlke, J. K., Plummer, L. N.,
Coplen, T. B.,
Busenbeberg, E., Chariton J., Burnett, W., Dillon, K., Corbett, R., 1996,
Assessing the
Origin and Fate of Ground Water in the Florida Keys, Florida Bay Science
Conference,
Program and Abstracts.
Reich, C. D., 1996, Diver-operated manometer simple device for measuring
hydraulic
head in underwater wells, Journal of Sedimentary Research Vol. 66, No.5, p.
1032-1034.
Shinn, E. A., Reich, C. D., Hickey, T. D., Tihansky, A. B. 1997, Geology
and tidal
pumping in the Florida Keys, AAPG annual meeting Dallas TX. abstracts p
106-107
Shinn, E. A., Reich C. D., Halley, R. B., Reese, R. S. 1995, Hydrogeologic
aspects of
sewage disposal in the Florida Keys GSA annual meeting New Orleans, abstract
Required Expertise:
1997 - Expertise in carbonate sedimentology, survey and sampling
techniques, coring, well
installation, boat operations, diving, GPS, Nutrient analyses, Flurometer
analysis.
1998 - Same as above but including modeling with visual modflow.
1999 - Ability to synthesis all of the results into a final report,
articles and presentations.
Names of Key Project Staff:
1997 - Shinn, Reich, Hickey and Tihansky
1998 - Shinn, Reich, Hickey, and Tihansky
1999 - Shinn, Reich, Hickey, and Tihansky
Major Equipment/Facility Needs:
1997: Coring platform, boat, cement,, coring equipment and miscellaneous
supplies for
completing wells (bits, rod, casing, PVC pipe, screens, cement, sand etc.)
1998: Same a above, and computer upgrades, lab facilities.
1999: Same as above.
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