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Group Title: Circular - University of Florida Cooperative Extension Service ; 939
Title: Excavated pond construction in Florida
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Permanent Link: http://ufdc.ufl.edu/UF00067068/00001
 Material Information
Title: Excavated pond construction in Florida
Series Title: Circular
Physical Description: 5 p. : ill. ; 28 cm.
Language: English
Creator: Haman, D. Z ( Dorota Z )
Clark, Gary A
Pitts, Donald J ( Donald James )
Publisher: Florida Cooperative Extension Service
Place of Publication: Gainesville
Publication Date: 1991
 Subjects
Subject: Ponds -- Florida   ( lcsh )
Farm ponds -- Florida   ( lcsh )
Fish ponds -- Florida   ( lcsh )
Excavation -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 5).
Statement of Responsibility: Dorota Z. Haman, G.A. Clark and D.J. Pitts.
General Note: Title from caption.
Funding: Circular (Florida Cooperative Extension Service) ;
 Record Information
Bibliographic ID: UF00067068
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 28923245

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Excavated Pond Construction in Florida1

Dorota Z. Haman, G.A. Clark and D.J. Pitts2


A pond can be a convenient and economical
source of water for agricultural use. Ponds can
provide the necessary water storage for irrigation,
livestock and fish production, fire protection or other
purposes (for more information see IFAS Bulletin
No. 257). The two basic types of ponds are
embankment ponds and excavated ponds.

A classical embankment pond can be formed by
constructing a dam or embankment across a stream or
watercourse where the depression is deep enough to
provide a water depth of at least 6 ft (1.8 m). An
excavated pond can be constructed by digging a pit or
a dugout area, typically in relatively flat topography
areas. Excavated ponds are generally small since their
capacity is obtained almost entirely by digging.
Because Florida's natural topography lacks significant
differences in slope, especially in the southern portion
of the state, excavated ponds are necessary to provide
adequate storage volumes for given surface areas.
However, in some parts of Florida the natural rolling
topography can be used to construct an embankment
pond. Even in those areas where the land may be
gentle to moderately sloping the required pond
capacity is frequently obtained by both excavation and
embankment. Some ponds required by local
regulatory agencies are used as retention areas for
runoff control, surface water quality control, wetland
preservation, and recharge of the shallow aquifer.
These retention ponds may be created by constructing
dikes across natural depressions and are a type of
embankment pond. In some areas of Florida where
naturally high water table conditions exist, such as in
South Florida, retention ponds are created by building
a dike around proposed pond areas to provide the
necessary storage.


This publication will provide information on
excavated ponds and will emphasize planning, site
investigation, construction and management
considerations.

EXCAVATED PONDS

Excavation is a pond construction method used in
relatively flat topography. The natural slope at the
site should not exceed 4 percent. Because all
material must be removed to obtain the desired
capacity, the size of a pond constructed by excavation
will be limited by excavation costs and site conditions.

Excavated ponds can be classified by the way
water enters the pond. An excavated pond can be
supplied by surface runoff, by water diverted from a
stream or a river, by water pumped from a well by
surficial aquifer sources (water table), by shallow
water table seepage, or by any combination of the
above sources. In Florida, shallow natural water
tables surficiall aquifer) and heavy rainfalls combine
to provide most of the water supply for excavated
ponds.

Excavated ponds which are supplied by surface
runoff should be located in natural depressions, in
broad natural drainage swales or paths, or to one side
of the drainage swales where the runoff can be
diverted into the pond. If the pond is constructed in
or near a natural drainage swale, excess runoff from
a full pond may be discharged through natural
drainage paths and construction of a spillway may not
be necessary.


1. This document was published March, 1991 as Circular 939, Florida Cooperative Extension Service. For more information, contact your county
Cooperative Extension Service office.
2. Associate Professor and Assistant Professor, Agricultural Engineering and Assistant Professor Southwest Florida Research and Education
Center, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville.

The Institute of Food and Agricultural Sciences is an Equal Opportunity/Affirmative Action Employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean
IWs rrSTY OF FLORIDA LIBRARIES






Excavated Pond Construction in Florida


Excavated ponds supplied by surficial groundwater
aquifers (natural high water tables) must be located in
flat or nearly flat topography. A prevailing, reliable
water table should be within 1 m (3 ft) of the ground
surface. The level of the water table indicates the
water level in the completed pond. In addition, the
shallow aquifer must be sufficiently large and
permeable to yield water at a rate that satisfies the
maximum expected demand for water. However, in
most Florida locations the yield is usually not a
limiting factor.

When the water table and surface runoff cannot
provide a sufficient supply of water, an additional
water supply such as a well or a diversion from a
nearby stream may be necessary. If the water level in
the pond is above the level of the natural water table,
significant losses can occur through subsurface flow
(Fig. 1). These losses can be significant in Florida
sandy soils and will depend on the permeability of the
bank material and on the difference in height between
the pond surface and the surrounding water table.


TO\ "
PMM


Figure 1. Losses from the pond due to the high water
level.

PLANNING AN EXCAVATED POND

Design of an excavated pond is based on the
required storage capacity, depth to the water table,
other available water sources, and the stability of the
side-slope materials. The topographic conditions at
the site must allow economical construction. Cost is
a direct function of the volume of excavated material
required to obtain a certain storage capacity in the
pond. This method of construction results in the
limited practical size of excavated ponds. However,
these ponds can be designed to minimize evaporation
losses by decreasing pond surface area in proportion
to stored volume.

A rectangular shape is usually the most
convenient for excavation equipment. The size of the
pond is determined by the purpose for which water is
needed, the site conditions, and the amount of inflow
that can be expected. The required capacity of an
excavated pond fed by a shallow water table is difficult


to determine since the estimated rate of inflow into
the pond can rarely be estimated with reasonable
accuracy. Long narrow ponds will yield (or lose)
more water from (or to) the surrounding area than
square ponds. In some cases it may be necessary to
augment the pond volume with water pumped from a
nearby well or other water source. More information
on pond sizing can be found in IFAS Extension
Bulletin 257.

The proposed pond site should be thoroughly
investigated prior to design and construction. Core
samples of the soil profile should be obtained to
provide information on the permeability of the
material within all depths and below the bottom of
the proposed pond. Permeability requirements for
pond construction vary with the type of water supply
into the excavated area. For a pond supplied by a
surficial aquifer source the permeability of the
surrounding soil must be high to assure sufficient
inflow into the pond. Conversely, a pond supplied
with water from another source as discussed above
must be located in an area with low permeability soils
in order to avoid seepage losses.

Permeability is defined as the readiness with
which soil transmits water under standard field
conditions. It depends primarily on the size and
shape of the soil grains, the porosity of the soil, the
shape and arrangement of the pores, and the degree
of saturation. There are several laboratory methods
to determine permeability for a given soil.

Indications of soil permeability can also be
obtained at the sites by filling test holes with water
and observing the seepage characteristics of the
material. Permeability tests performed in the field
are frequently more representative of the actual site
conditions since the soil is not disturbed as much as
when the samples are transferred from the field to
the laboratory. The simplest method used in the field
in the presence of high water table is to dig an auger
hole into the soil below the water table. First
determine the elevation of the existing natural water
table by allowing the water surface in the hole to
reach equilibrium with the surrounding area. Next,
the water in the auger hole is pumped out to lower
the elevation of the water surface in the hole, then
the rate of rise of water in the hole is measured.
From this measurement soil permeability can be
calculated. I I
(o,3 (, c


t.1#RAWY


Page 2






Excavated Pond Construction in Florida


At sites without natural water tables, other
permeability tests must be used. An infiltration test
over a large area (13 ft or 4 m in diameter) may be
used as a field test. This avoids the soil compression
that is inherent in core sampling, which is necessary
for the lab samples. The area is diked with a ring of
soil and filled with water to form a shallow pond. A
circular pond is recommended rather than a
rectangular one because the circular pond has less
lateral and undesirable seepage loss per unit area
than a rectangular one. To perform this test water is
added to the pond area as needed to saturate the soil
in the surrounding area, then the falling water level of
the pond in the absence of added water is observed
and used to determine permeability. This rate should
be a measure of the ability of the soil to pass water
into and through the observed soil layer.

When excavated ponds are supplied by surface
runoff or by water pumped from a well, relatively
impervious soils at the site are essential to avoid
excess seepage losses. Soil materials must be
available to provide a stable, impervious fill where
needed. Clays and silty clays are the most desirable,
however sandy clays may also be satisfactory. In some
regions of the Florida Panhandle, the soils contain
sufficient clay to allow pond construction without
adding soil amendments or artificially lining the pond.
Unfortunately, most of the soils in peninsula Florida
are very sandy, and additional measures to prevent
seepage are necessary for pond construction. In some
cases the only solution may be an artificial lining
material. An artificial lining is expensive but should
be considered at sites where soils are porous or are
underlined by sands or gravel. Methods of pond
sealing are discussed in IFAS Extension Circular 870.

In addition to permeability tests, the core sample
holes may be used to determine the existing level of
the water table from the shallow aquifer. The depth
to the water table generally varies throughout the
year. Therefore, several observations may be
necessary to help with design. The performance of
other nearby ponds may provide useful information
with respect to the suitability of the proposed site and
for design purposes.

Larger ponds should be equipped with some
drainage facilities. A drain pipe is necessary to
facilitate maintenance and fish management. On flat
topography a pump may be necessary to drain the
pond.


EXCAVATED POND CONSTRUCTION

Proper construction practices should be followed
to ensure safety and to reduce potential problems.
After the pond site has been selected, an area or
areas for spoil placement (excavated material) should
be located. Stake the boundaries of the pond and
spoil placement locations with the depth of cut from
the ground surface to the pond sides or bottom
clearly marked on the stakes. All woody vegetation
should be cleared from these areas.

The type of excavating equipment for construction
will depend on availability, climate, and physical
conditions at the site. During dry periods most types
of equipment can be used. The most common are
tractor-pulled wheeled scrapers, draglines, and
bulldozers. Inefficiency in transporting material limits
the use of a bulldozer for excavation to relatively
small ponds. Dragline excavators are commonly used
for pond construction in the high natural water table
areas of Florida. This is the only type of equipment
that will operate under saturated soil conditions.

It is desirable to keep topsoil separated from
subsoil materials during excavation. Place topsoil
material in a location where it can be accessed after
excavation has been completed. After excavation, this
material should be placed on the surface of the side
slopes, berms, spoil banks and spillways. These areas
should be seeded or plugged with a grass or other
cover material for erosion control. The grass or
cover material should require minimal maintenance,
be tolerant to local drought or wet conditions, and be
relatively easy to establish.

INLETS

If the runoff is entering the pond through a
confined channel or ditch rather than through a broad
shallow waterway or watercourse, the pond inlet must
be protected against erosion. A steel or concrete
culvert can be placed in the ditch and extended over
the side of the excavation (see Fig. 2). The extended
portion of the pipe should be either cantilevered or
supported with timbers. Pipe diameters depend on
the peak rate of inflow and must be appropriately
sized (see Table 1). If the water is carrying significant
amounts of silt or suspended particles, a
sedimentation area or filtration strip planted with
grass should be provided above the pond to remove
the sediment before water enters the pond.


Page 3







Excavated Pond Construction in Florida


\


Figure 2. Cantilivered pipe delivering runoff to the
pond.


Table 1. The diameter of the inlet pipe or pipes based
on the peak rate of runoff that can be expected into
excavated ponds*.

Pipe Pond inflow GPM
diameter Q (ft3/sec)
(inches)**

15 0 to 6 0 to 2694 (2700)
18 6 to 9 2700 to 4000
21 9 to 13 4000 to 5800
24 13 to 18 5800 to 8100
30 18 to 30 8100 to 13500***
*After SCS Engineering Field Manual.
**Inlet pipe size based on a free outlet and a
minimum pipe slope of 1.0 percent with the
water level 0.5 foot above the top of the pipe
at the upstream end.
***It is recommended that for larger flow
rates a design expert be consulted before inlet
construction.


SPILLWAYS

It may be necessary to provide a system which can
be used to drain the pond as both a management and
maintenance practice. If gravity drainage is not
possible, a pumping system will be necessary. In
addition, surface drainage may be necessary to
properly route excessive water inflows. This may be
accomplished through drainage culverts or grassed
spillways. Concrete spillways are expensive but may
be necessary on larger ponds and where excessive
flows may be expected. An emergency spillway is not
required on ponds with no runoff discharging into
them.


If an excavated pond is located on sloping terrain,
part of the excavated material can be used to build a
small dam on the lower side of the pond to increase
the pond's capacity. Care must be taken that failure
of this dike does not result in adverse downstream
impacts. An emergency earth spillway is necessary to
pass excess storm runoff around the small dam. If the
pond is being supplied by surface runoff, the capacity
of the emergency spillway should be sufficient to
discharge the maximum outflow expected for a rainfall
frequency of once in 25 years. For large ponds the
design rainfall is 100 years. The emergency spillway
may consist of a concrete or vegetated earthen
spillway, a conduit (pipe), or a combination of a
vegetated spillway and a conduit. If a vegetated
spillway is used, the crest of the spillway should be at
least .06 m (.2 ft) above the normal reservoir water
elevation.

A trickle spillway is usually designed to provide
flood protection or to reduce the frequency of
operation of the emergency spillway. For more detail
on sizing requirements of spillways, the reader is
advised to contact a licensed engineer or consult with
the local Soil Conservation Service.

FILTER STRIP DESIGN

Sediment leaving agricultural land is often a
significant source of pond nonpoint pollution. This
sediment delivery can be reduced by grass filter strips
near the edge of the field or the disturbed area.
Filter strips increase the hydraulic roughness of the
flow surface, reducing the flow velocity and thus the
transport capacity. Since concentrated flows tend to
submerge the grass and decrease the roughness, filter
strips are most effective when flow is shallow and
enters the strip uniformly along its length. Thus, care
in placement and maintenance of filter strips is
advised. Assistance in the design of filter strips is
available through the Soil Conservation Service.

SEALING PONDS

The selection of a sealing method depends largely
on the proportions of coarse grained sand and gravel
and fine materials like silt and clay in the soil. A soil
scientist should be consulted before a sealing method
is selected. In some cases it may be necessary to
perform a laboratory test of the materials from the
selected site. For more information of pond sealing
methods the reader is referred to IFAS Extension
Circular 870.


Page 4






Excavated Pond Construction in Florida

ALGAE CONTROL

Excessive algae growth often occurs within ponds
and can result in many problems. The algae can be
effectively treated with copper sulfate (CuSO4).
Applications of 1 to 2 ppm (1.4 to 2.7 pounds per
acre foot) CuSO4 are sufficient and safe to treat algae
growth and should be applied when the pond water
temperature is above 600 F. Treatments may be
repeated at 2- to 4-week intervals, depending on the
nutrient load in the pond. Copper sulfate should be
thoroughly mixed into the pond (i.e., sprinkled into
the wake of a boat). As with other biocides,
distribution into surface water must be in compliance
with EPA regulations.

Copper sulfate can be harmful to fish if alkalinity,
a measure of the water's capacity to neutralize acid,
is low. Alkalinity is measured volumetrically by
titration with sulfuric acid (H2S04) and is reported in
terms of equivalent calcium carbonate (CaCO3).
Table 2 provides a reference for determining the
amount of copper sulfate to add given different
alkalinity levels. Repeated use of copper sulfate can
result in a toxic accumulation of copper for aquatic
plants.

Table 2. Copper Sulfate (CuSO4) Levels Safe
for fish.

Alkalinity Value Addition of Copper
(CaCO3, mg/1) Sulfate

below 40 do not use
40-60 1.0 lb per acre-ft of water
60-100 1.3 lb per acre-ft of water
over 100 2.7 lb per acre-ft of water
1 ppm = 2.7 lb per acre-ft
(Dupress and Huner, 1984)



SUMMARY

Construction of excavated ponds in Florida, with
emphasis on planning, site investigation, and
management considerations, was presented. Due to
the relatively flat topography in many parts of Florida,
excavated ponds are constructed quite frequently
throughout the state. Ponds can provide a convenient


Page 5


and economical source of water for agricultural use.
However, proper management and maintenance may
be necessary to avoid pond degradation due to
erosion, seepage losses, algae blooms, or other
undesirable conditions.

REFERENCES

Clark G.A., C.D. Stanley, F.S. Zazueta, E.E. Albrets.
1988. Farm Ponds in Florida Irrigation Systems.
Institute of Food and Agricultural Sciences,
University of Florida, Gainesville FL. Extension
Bulletin 257.

Dupress H.K. and J.V. Huner. 1984. Third Report of
the Fish Farmer. United States Department of
Interior, Fish and Wildlife Service. Washington,
D.C. 202 pp.

Flanagan D.C., G.R. Foster, W.H. Neibling, and J.P.
Burt. 1990. Simplified Equations for Filter Strip
Design. Transactions of the ASAE 32(6):2001-
2007.

Haman D.Z., A.G. Smajstrla, F.S. Zazueta, G.A.
Clark. 1990. Selecting a Method for Sealing Ponds
in Florida. Institute of Food and Agricultural
Sciences, University of Florida. Gainesville FL.
Extension Circular 870.

Ogrosky H.O. and V. Mockus. 1964. Hydrology of
Agricultural Land. In: Handbook of Applied
Hydrology, Ed. V.T. Chow. McGraw-Hill, New
York.

Soil Conservation Service. 1984. Ponds and
Reservoirs, Chapter 11. In: Engineering Field
Manual. United States Department of
Agriculture, Soil Conservation Service,
Washington, D.C.

U.S. Army Corps of Engineer Service. 1970.
Laboratory Soils Testing. Manual EM 1110-2-1906
Department of the Army, Office of the Chief of
Engineers, Washington, D.C.

U.S. Department of Agriculture, Soil Conservation
Service. 1982. Ponds Planning Design,
Construction. Agricultural Handbook Number
590.2.









HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






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