Download Drainage - Citrus County Board of County Commissioners

CHAPTER FIVE
INFRASTRUCTURE
ELEMENT
DRAINAGE SUBELEMENT
Updated:
EAR BASED AMENDMENTS
July 11, 2006, Ord. No. 2006-A12
December 11, 2007, Ord. No. 2007-A37
(Sanitary Sewer Sub-element)
September 16, 2008, Ord. No. 2008-A27
(Sanitary Sewer and Potable Water Sub-elements)
November 10, 2009, Ord. No. 2009-A24
(Sanitary Sewer and Potable Water Sub-elements)
February 14, 2012, Ord. No. 2012-A02
(Drainage Sub-element)
February 26, 2013, Ord. No. 2013-A04
(Potable Water Sub-element)
February 25, 2014, Ord. No. 2014-A06
(Drainage Sub-element)
February 28, 2017, Ord. No. 2017-A09
(Sanitary Sewer, Potable Water, and Drainage
Sub-elements
Infrastructure Element
Drainage Subelement
I.
INTRODUCTION
A. Purpose
Proper stormwater drainage is essential for adequate protection of the County’s water
resources and public health and safety. The potential environmental and economic
impacts of uncontrolled stormwater drainage have led to a management and
regulatory framework established by local, state, and federal government.
The purpose of this element is to establish the County’s policy directives for
managing stormwater drainage. The characteristics of drainage patterns and
associated limitations within Citrus County are incorporated into the drainage plan.
B. Terms and Concepts
1. Drainage Systems
Water flowing overland during and immediately following a storm event is called
stormwater runoff. Under the effect of gravity, water flows towards sea level
through depressions and channels or by sheetflow over flat terrain. The drainage
system may consist of natural features, manmade features, or a combination of
both.
Natural drainage systems are defined by the topography of an area. The largest
feature is the drainage basin or watershed. The boundary of a basin is referred to
as the basin divide. The basin divide is a line where the natural land elevation
directs runoff within the basin toward a common major drainage feature. A major
drainage feature is referred to as a receiving body and smaller features are
tributaries.
Manmade drainage facilities features are designed to detain, store, or convey
stormwater runoff. Swales, ditches, canals, and storm sewers are typical
conveyance structures, which collect stormwater runoff and direct it toward
downstream receiving facilities. Stormwater storage structures are classified as
either detention or retention facilities. Detention facilities are designed to
temporarily impound runoff and release it gradually to downstream portions of
the drainage system through an outlet structure. Retention facilities are
impoundments, which release stormwater by evaporation and percolation, with no
direct discharge.
2. Drainage and Stormwater Management
Stormwater runoff is highly variable and dependent upon the amount of rainfall
during each storm event and conditions of the drainage basin. Since most storm
events are relatively moderate, natural drainage features typically evolve to
accommodate moderate quantities of runoff. Periodically, severe storm events
5-120
Infrastructure Element
Drainage Subelement
create runoff volumes exceeding these drainage features holding capacities,
resulting in temporary high water levels. This periodic high water level (flood) is
a naturally occurring event and has many beneficial effects in the cycle of the
basin’s ecosystem. Flooding or high water levels are generally not perceived as a
problem until development occurs in floodprone areas.
Historically, the typical strategy adopted in response to stormwater flooding of
developed areas was to modify the drainage system to convey runoff away from
developed sites more rapidly. This strategy with increasing urbanization results in
proportionately faster runoff during storm events.
In addition to controlling flood problems, this strategy for coping with stormwater
runoff has detrimental effects on water quality. Soil eroding from development
sites and materials such as oil, grease, pesticides, and fertilizers from urban and
rural land uses are washed off by runoff, increasing the pollutant loading on
receiving waters.
The term “stormwater management” refers to comprehensive strategies for
addressing stormwater quantity and quality issues. The combined goal of
stormwater management strategies is to ensure that the volume, rate, timing, and
pollutant load of runoff after development is similar to that which occurred prior
to development. To accomplish this, a combination of structural and
nonstructural techniques is utilized. Structural techniques emphasize detention
and retention of stormwater to reduce runoff rates and provide settling and
filtration of pollution. Nonstructural techniques emphasize preservation or
simulation of natural drainage features to promote infiltration, filtering, and
reducing the rate of runoff. The objective of stormwater management is to utilize
the combination of techniques, which provides adequate pollution removal and
flood protection in the most economical manner.
C. Regulatory Framework
The U.S. Environmental Protection Agency has published rules to implement the
National Pollutant Discharge Elimination System (NPDES) as mandated under
Section 402(p) of the Clean Water Act. The State of Florida submitted a request to
the EPA for delegation of NPDES permitting. A main component of this permitting
process will be submittal of a Stormwater Pollution Prevention Plan (SWPPP) to
identify and mitigate both stormwater and non-stormwater flows.
In Florida, the DEP is responsible for regulating stormwater throughout Florida. This
regulatory role has been delegated by the DEP through a formal agreement to the
Southwest Water Management District (SWFWMD). Within Citrus County, the
SWFWMD is responsible for stormwater drainage.
5-121
Infrastructure Element
Drainage Subelement
Sections 373 and 402, F.S., provide the SWFWMD specific authority to regulate
stormwater drainage. Chapter 40D-4 and 40D-40, F.A.C., provide rules within
SWFWMD for the management and storage of surface waters.
Locally, stormwater management is regulated by the County. The Department of
Public Works administers the requirements of the Stormwater Drainage Appendices
of the LDC.
II.
INVENTORY
A. Background
The Southwest Florida Water Management District has identified watershed
management as a major component for protection of water resources and the
environment.
State Water Policy defines a watershed management goal as “an overall goal which
provides the general strategies for the management of water resources within a
watershed”.
The goal will be developed to be consistent with the Surface Water Improvement and
Management (SWIM) program(s) and the NPDES program.
The U.S. Geological Service has delineated watersheds at four levels of detail. Level
One delineations show approximately 10 watersheds in the SWFWMD up to Level
Four showing 1,000 watersheds. An interdisciplinary SWFWMD staff workgroup
has chosen 23 delineated basins, comprised of watershed from Levels One and Two
for development of preliminary watershed management goals.
The District will prepare a comprehensive surface water approach that will
encompass flood protection, water quality, natural systems management, and where
appropriate, water supply considerations. The results of this initiative will be used for
a variety of purposes including specific implementation strategies for each watershed
in conjunction with federal, state, and local agencies. Intergovernmental coordination
will then prioritize activities to provide maximum effective use of available funding.
1. Basins and Subbasins
Citrus County is divided by a drainage divide, which forms the Coastal Rivers and
Withlacoochee Basins. This drainage divide begins in the south central area of
the County and gradually curves westward below the junction of the
Withlacoochee River and the Gulf of Mexico (Figure 5-11).
The Coastal Rivers Basin is drained by the Crystal, Homosassa, Halls, and
Chassahowitzka Rivers. These river systems receive the majority of their volume
from coastal springs and the seepage of groundwater, rather than surface runoff
5-122
Infrastructure Element
Drainage Subelement
from the surrounding watershed (Glace and Radcliffe, Inc., 1981). However,
stormwater runoff is increasing due to urbanization of the lands within the
respective watersheds.
The Coastal River Basin consists of a large buffer area of saltwater marsh
bordered by a land of freshwater swamp west of US-19. Traveling east from US19 the land elevations increase to a maximum at the eastern edge of the basin,
which is located in the sand hills (Brooksville Ridge). Whereas the sand hill areas
provide excellent infiltration and recharge for stormwater runoff, the areas
bordering US-19 contain poorly drained soils that require appropriate stormwater
management techniques to protect water quality.
The Coastal Rivers Basin has been divided into 27 subbasins (Figure 5-11). The
land area contained in each subbasin is shown in Table 5-12. Since drainage
basins do not conform to political boundaries, some of these subbasins consist of
portions outside the County. Particular basins as noted were calculated to include
only that portion which is in Citrus County. The Coastal River Basin contains the
Crystal River/King’s Bay area, which is a designated SWIM project. The County,
in coordination with the City of Crystal River and SWFWMD, have implemented
strategies developed under this program, as well as, utilized them in other areas
within the Basin when applicable.
The Withlacoochee River Basin covers the eastern half and northern edge of
Citrus County (Figure 5-11). The Withlacoochee River, the major drainage
feature of the Basin has its headwaters in the Green Swamp. The river meanders
157 miles northward to the Gulf of Mexico and forms the eastern and northern
boundaries of Citrus County. This Basin is divided into 39 subbasins, which are
listed in Table 5-13.
TABLE 5-12
COASTAL RIVERS BASIN
Subbasin
Area (acres)
Subbasin
Area (acres)
C-1
40,967
C-15
1,690
C-2
13,594
C-16
657
C-3
2,773
C-17
3,996
C-4
3,240
C-18
547
C-5
3,140*
C-19
6,575
C-6
1,631
C-20
680
C-7
2,149
C-21
2,182
C-8
1,466
C-22
7,221
C-9
812
C-23
5,781
C-10
1,051
C-24
6,465
C-11
1,153
C-25
1,785
C-12
10,626
C-26
88,760*
C-13
13,407
C-27
1,377
C-14
1,690
Note: *Area of Basin within Citrus County
Source: Glace and Radcliffe, Inc., 1981
Prepared by: Citrus County Community Development Division, 1986
5-123
Infrastructure Element
Drainage Subelement
TABLE 5-13
WITHLACOOCHEE RIVER BASIN
Subbasin
Area (acres)
Subbasin
Area (acres)
W-1
2,094
W-21
1,381
W-2
5,748
W-22
2,773
W-3
1,093
W-23
8,230
W-4
13,028*
W-24
900
W-5
1,387
W-25
4,885
W-6
3,636
W-26
1,965
W-7
10,257*
W-27
6,511
W-8
1,644
W-28
1,230
W-9
2,747
W-29
2,571
W-10
1,230
W-30
3,453
W-11
2,213
W-31
3,398
W-12
753
W-32
1,253
W-13
2,130
W-33
2,002
W-14
2,610
W-34
1,702
W-15
2,525
W-35
5,811*
W-16
1,286
W-36
7,686
W-17
4,623
W-37
16,621
W-18
9,972
W-38
4,011
W-19
1,747
W-39
12,635
W-20
3,737
Note: *Area of Basin within Citrus County
Source: Glace and Radcliffe, Inc., 1981
Prepared by: Citrus County Division of Planning, 1966
2. Environmental Factors
There are many factors, which affect the surface water drainage of a basin or
watershed. These factors include climate, topography, geology, hydrology, and
soils. The following discussion summarizes these factors by characterizing
drainage within Citrus County. A more detailed discussion is contained within
the Conservation Element.
The climate of Citrus County is typical of a low-lying subtropical area. The
summers are warm and relatively humid, while winters are mild and relatively
dry. Citrus County receives 55 inches of rainfall annually. More than one-half of
the annual rainfall occurs during the months of June through September.
5-124
Infrastructure Element
Drainage Subelement
5-125
Infrastructure Element
Drainage Subelement
Topography of the County is characterized by low-lying, flat terrain, karst
geology, a thin soil profile and extensive salt and freshwater wetlands along the
coastal lowlands. The topography gradually rises in elevation and varies in
landscape traveling eastward from the coast. Paralleling US-19 on the east is a
nearly level sand terrace with elevation from 10 to 20 feet above mean sea level.
East of this terrace a sand ridge is encountered where the land rises as high as 237
feet above mean sea level and 180 feet along the ridge crest. East of the sandhills
the land elevations decrease towards Lake Tsala Apopka and the Withlacoochee
River.
Surficial geology of the County consists of sand with a scattered distribution of
clays in the Central Ridge Area and karst geology along both the east and west
portions of the County. Due to topographic and geologic features runoff is
generally greater in the Coastal, Lakes, and River Areas of the County, rather than
the Central Ridge. Stormwater in the Central Ridge permeates through the sand
layers, whereas in the lake and coastal areas, stormwater permeability is inhibited
by water table and soil characteristics.
Soil associations within the County are categorized based on limitations to
drainage. These soil groups with limitations on permeability should be
considered during the review of proposed impacts to water quality relating to
various stormwater management alternatives. Soil types have direct relationships
with stormwater management parameters such as: permeability, erosion potential,
infiltration, and filtration. These parameters control both the quantity and quality
of water, which recharges the aquifer or becomes runoff.
The hydrology of the County is characterized by the surface waters of the
Withlacoochee River and the Tsala Apopka Plain, the Coastal Rivers, and the
high recharge area of the Central Ridge. The hydrologic characteristics of the
major surface water features demonstrate that the Withlacoochee River receives a
significant portion of its flow outside of Citrus County (Green Swamp and related
watersheds) and the coastal rivers are primarily fed by groundwater discharge.
A significant portion of rainfall in the County percolates to the Floridan aquifer or
a surficial aquifer, providing a regeneration of groundwater necessary for water
consumption, protection against increased sinkhole activity, and the maintenance
of hydrologic levels in wetlands, springs, and waterbodies. It is important to
retain historical aquifer recharge rates in order to maintain aquifer levels.
Runoff from storm events can cause significant detriment to water quality and the
safety of the residents. Appropriate measures for controlling and treating runoff
are necessary for protection of the public health, safety, and welfare.
5-126
Infrastructure Element
Drainage Subelement
3. Development Pressures
Land development impacts the natural drainage patterns and function of land
areas. Development or urbanization increases the amount of impervious surfaces,
thus, increases the amount and rate of stormwater runoff. Rainfall, which
contacts impervious surfaces, washes oil, grease, sediments, residuals, and other
pollutants into the receiving bodies. Runoff also transports sediments, fertilizers,
pesticides, herbicides, and increases the leachate from agricultural, landscaped,
residential, and other similar land areas.
Stormwater runoff conveys many pollutants including suspended solids, heavy
metals, nitrogen, phosphorus, pesticides, herbicides, fertilizers, and organic
materials. These pollutants have degrading effects on water quality. The addition
of pollutants of this nature reduces dissolved oxygen concentrations, increase
eutrophication, increase public health risks, increase siltation, and reduce aesthetic
values.
Increasing volumes and runoff rates from an urbanizing landscape can lead to the
flooding of low-lying areas and areas, which previously had no flooding
problems. As development continues, runoff rates and volumes increase.
B. Stormwater Drainage Plans and Studies
1. Citrus County: Stormwater Drainage Study
Glace and Radcliffe, Inc., completed a stormwater drainage study in July 1981 for
Citrus County. This study delineates subbasin boundaries, identified existing
control structures, identified wetland and recharge areas, and recommended
stormwater management practices.
Conclusions from the stormwater drainage study are listed below:
•
•
•
•
•
•
Citrus County has many well-defined drainage basins and adequately
sized drainage structures.
The growth and urbanization, which is occurring in Citrus County, could
have deleterious effects on water quality.
As growth continues, the County will become more urbanized and the rate
of delivery of stormwater in the respective basins and subbasins will
increase.
The County should take action to protect area water quality and preserve
its vital natural resources.
The County should implement regulations as required to enhance
stormwater management contribution to life and environmental quality.
The County should be cognizant that the implementation of both structural
and nonstructural alternatives for stormwater management may be
5-127
Infrastructure Element
Drainage Subelement
required in the future and that the appropriation of funds to accomplish
these stormwater objectives will be necessary.
Specific recommendations from the stormwater drainage study are:
•
•
•
•
The County Commission accepted this report as the basis for making
future decisions on stormwater management practices and implementing
future improvements to the County’s primary drainage system.
The County proceed with the adoption of stormwater management
regulations.
The County perform site specific, stormwater management evaluations
using this study as a database.
The County administer proper land use and water conservation regulations
and prohibit development in these flood prone areas where it would be
detrimental and not in the best interest of Citrus County.
2. Five Year Plan: Drainage Improvements
The Drainage Improvements Plan prepared by the Department of Technical
Services in October 1986 provided a prioritized list of improvements through the
year 1990. These improvements were estimated to cost approximately $582,000
to the year 1990. Additional projects are added each year as older projects are
completed. A current listing of projects is contained within the Capital
Improvements Element.
Each project within the drainage improvement plan was evaluated based on seven
factors, which include:
•
•
•
•
•
•
•
Residential Units Affected
Commercial Units Affected
County Roads Affected
Frequency of Flooding
Length of Time-Standing Water
Average Daily Traffic/Affected Roadways
Flooding Area (acreage)
These factors were inventoried and a score was calculated. The point score was
then divided by the estimated cost to rank the project in priority order.
These improvements were generally site specific in areas experiencing flooding
conditions during various storm events. The Department of Technical Services
was responsible for the planning and design of such improvements and the
Department of Public Works was responsible for the construction and
maintenance of the facilities. In many cases the improvements were remedial and
may be of emergency nature. Since the improvements are not the portion of a
comprehensive drainage plan for the subdivision or a portion of a stormwater
5-128
Infrastructure Element
Drainage Subelement
master plan for a subbasin, the pollutant and filtering functions were not always
met.
3. Beverly Hills Stormwater Study and Plan
This study was prepared for Citrus County in December 1982. The Beverly Hills
Development was platted prior to stormwater drainage design requirements in the
County. Numerous drainage problems occurred within the subdivision. The
County authorized the preparation of this study to develop an overall stormwater
master plan for Beverly Hills, Units One through Five. The initial design was
intended to comprehensively address and effectively manage stormwater
drainage. Based on this study, the County has addressed problem drainage areas
in many areas of Beverly Hills. This program is ongoing.
4. Highlands Stormwater Study
The Highlands Stormwater Study was commissioned by the County to address
drainage problems within a portion of the Inverness Highlands Subdivision. This
study covers a land area of approximately 1,110 acres. The study identified
drainage patterns and problems. Strategically located properties were acquired
through an assessment program and some drainage facilities have been
constructed. This project is ongoing and is revisited periodically as development
and infill occur.
III.
NEEDS ASSESSMENT
A. Stormwater Drainage Regulation
1. Citrus County
Citrus County’s stormwater drainage regulations are embodied in the Citrus
County Land Development Code and Appendices C.O. 90-14. These regulations
contain level of service standards for drainage facilities and specific design
standards.
The Department of Public Works is responsible for enforcement of this ordinance.
Their main role in administering these ordinances lies within the subdivision
(plat) review procedures. The construction of a single family residence is
conditionally exempt from requirements of this ordinance. The conditional
exemption does not include requirements of Section 3, Subsections (4) and (5),
which state:
5-129
Infrastructure Element
Drainage Subelement
(4) Special Cases
“Single family dwellings, including duplexes, shall be constructed in such a
manner as to prevent flooding from stormwater entering the site from
adjacent properties, including roadways.
Residential sites within a Master Drainage Area shall provide approved
drainage methods, as to prevent direct runoff onto adjacent properties. All
other residential sites shall be graded in such a manner as to provide on-site
retention of the first one (1) inch of stormwater runoff for the developed area
of the lot and to prevent direct runoff onto adjacent properties.
(5) All Systems (including Special Cases)
Whenever stormwater runoff is designed to enter any body of water, including
roadside ditches and swales, special engineering features designed to remove,
oils, suspended soils, and other objectionable materials shall be required.
To the maximum extent possible, designs shall include methods to retain
stormwater in natural recharge areas.”
The Department of Public Works is responsible for planning engineering and for
the construction and maintenance of drainage facilities for the County operated
facilities.
The Land Development Code contains requirements that drainage facilities and
conveyance systems be constructed to meet specific storm duration events. These
specific standards are located in Appendix A and B of the Land Development
Code.
A summary of requirements for stormwater management include:
•
•
•
•
•
•
Calculations for runoff shall consider the entire contributory watershed
including area outside of the subdivision
Natural collection facilities which direct runoff from the subdivision on to
adjacent properties must be perpetuated to the extent of protecting the
upland owners interest; however, such facilities must not be incorporated
into the drainage design for the subdivision
The collection of stormwater runoff shall be by positive gravity means
without the use of siphons, pumps, or similar devices
Calculations shall be based on commonly accepted engineering
procedures such as S.C.S, TR-55 or the rational method (Q=CIA).
All developers must retain or detain only the additional runoff caused by
their development
If, prior to development, stormwater flows either from or through the site
under review to an adjacent property, that predevelopment peak runoff
5-130
Infrastructure Element
Drainage Subelement
•
•
•
rate shall be calculated and, with either detention or retention facilities
incorporated in the drainage design, post development drainage shall be
performed which demonstrate that the peak runoff rates onto adjacent
properties will not be increased during a 25-year, 24-hour storm event
(open basin) or a 100-year, 24-hour storm event (closed basin)
It shall also be demonstrated that for the same design storm, there will be
no increase in backwater onto an upstream property and that any increase
in volume of runoff will have been detained and released at a time which
will not cause any increased flooding downstream
It shall be demonstrated that the design of all site drainage facilities shall
not cause flooding of public streets or buildings during a 25-year, 24-hour
storm event (open drainage system). 3-year, 24-hour storm event for
closed drainage system (curb and gutter)
Culverts within an open drainage system shall be designed to discharge a
10-year frequency storm without static head at the entrance and a 25-year
frequency storm utilizing available head at the entrance
2. Southwest Florida Water Management District (SWFWMD)
The SWFWMD surface water management rules (Chapter 40D-4 and 40D-40,
F.A.C.) provide regulations for the construction and operation of any new surface
water management system or the alteration of any surface water management
system. Exemptions from the surface water management rules included specified
agricultural and mining lands, permitted development prior to October 1, 1984,
and the construction of single-family residences (refer to Chapters 40D-4 and
40D-40 for specific list of exemptions).
B. Capacity and Performance of Facilities
The capacity and performance of drainage facilities refers to the capacity of
conveyance channels, and the relation to water quantity and quality, respectively. A
comprehensive study of drainage facilities was conducted in the Stormwater Drainage
Study, (Glace and Radcliffe, Inc., 1981). This study stated that Citrus County has
many well defined drainage basins and adequately sized drainage structures.
Areas of the County without stormwater drainage facilities or adequately designed
facilities are numerous. These areas have a mixture of drainage problems relating to
lack of facilities, soils with low infiltration rates, and poor subdivision designs. These
areas are found in the Coastal, Lakes, and River and Central Ridge Areas of the
County.
Existing drainage facilities have not been analyzed for either capacity or performance.
In many cases, the post-development peak has not been reached and facilities appear
to be designed and constructed over capacity, due to the lack of standing water.
5-131
Infrastructure Element
Drainage Subelement
IV.
DRAINGE PLAN
A. Level of Service
The County’s regulations shall utilize the 25-year, 24-hour storm event (open basin)
and a 100-year, 24-hour storm event (closed basin) for the construction of drainage
facilities and require the water quality treatment of the first one-half inch of runoff.
This storm event is utilized as a level of service for predevelopment and postdevelopment stormwater requirements. The SWFWMD was delegated responsibility
to regulate stormwater from the DEP in accordance with Chapter 62-25, F.A.C. The
SWFWMD utilizes the 100-year, 24-hour storm event in their stormwater design
requirements. The County also uses the 100-year, 24-hour storm event and the
retention of the first one-half inch of runoff for the drainage level of service for all
new subdivisions or planned developments. The SWFWMD requires retention of the
first one-half inch up to one and a half inches of runoff depending on the basin type,
location, and physical characteristics of the development.
Existing regulations and programs, which govern land use and development of natural
drainage features, are contained within the LDC. They include regulations that
address the protection of natural drainage inclusion of protective measures for natural
drainage features.
The level of service for drainage plans and facilities for all new subdivision or
planned development is as follows:
1. For open basins - the retention of the first one-half inch of runoff or a volume
of 50 percent more for discharge into Outstanding Florida Waters (OFW)
(water quality/pollution) and the 25-year, 24-hour storm event (water
quantity/flooding);
2. For closed basins - the retention of the first one-half inch of runoff or a
volume of 50 percent more for discharge into (OFW) (water quality/pollution)
and the 100-year, 24-hour storm event (water quantity/flooding).
The County regulations require that the first one-half inch of runoff is retained on-site
for single-family residences (except when a Master Drainage Plan is in place).
The County’s adopted level of service has been adjusted to match the SWFWMD
water quality and water quantity criteria.
5-132
Infrastructure Element
Drainage Subelement
B. Natural Features and Drainage
Natural features and drainage are important to preserve. These features include high
recharge areas and natural drainage patterns. Protection of these functions and
resources is beneficial in multiple areas: 1) filtering and recharging our potable water
supply aquifers, 2) reducing the potential of increased sinkhole activity, 3)
maintenance of flows to streams and springs, 4) providing natural filtering prior to
discharge into surface waters, and 5) reducing the costs of developing drainage
systems in areas where natural features are utilized in conjunction with manmade
drainage facilities.
Development standards in areas of high recharge are necessary to preserve the
functions of such lands. Drainage facilities in recharge areas shall utilize facilities
which maintain the volume of historical recharge and provide adequate filtering and
water quality treatment to prevent nutrients and contaminants from entering the
potable aquifer. In all cases, no drainage is allowed to discharge into sinkholes or
direct openings to aquifers providing potable water (refer to the Conservation
Element for groundwater protection measures). Where the likelihood of sinkholes
exists, all proposed drainage retention and water quality treatment areas should be
inspected through geotechnical testing for the presence of cavities and voids beneath
the proposed location.
Natural drainage patterns are important to preserve, as they are the lands existing
drainage facilities. If development of the watershed does not include a
comprehensive analysis of such drainage, the result is a basin, which will have
potentially expensive and hazardous conditions.
C. Stormwater Drainage Plans
Currently, there are limited (Homosassa Southfork) stormwater drainage plans for
establishing a unified effort to adequately facilitate stormwater drainage, although the
County currently is entering into a Memorandum of Understanding (MOU) with the
SWFWMD. The MOU will provide for detailed aerial photography and mapping,
watershed analysis, watershed development impact modeling, and identification of
needed projects, among other things. Many efforts and expenditures are being made
to correct drainage problems throughout the County. The development of master
drainage plans for subbasins or small groups of subbasins can establish the desired
goal for meeting stormwater needs within affected subbasins. These plans can
coordinate the individual improvements within a subbasin to meet the overall
stormwater drainage needs and requirements.
5-133
Infrastructure Element
Drainage Subelement
D. Regional Stormwater Drainage Plans
A regional stormwater drainage plan is proposed for the County Road 491 roadway
improvements from W. Laurel Street to south of W. Audubon Park Path. Currently,
stormwater management facilities within the county are provided individually by each
development, whether it is through a single site or as part of an overall master
planned development or a subdivision.
These systems, especially the stormwater ponds, typically require a large amount of
land to assure that the requirements for collecting and treating the stormwater from
any rain event are met. These systems can also be costly to design, permit and
construct.
Citrus County has a number of commercial sites that have already been developed
utilizing the concept of regional drainage. For many of these a regional drainage
retention pond accepts the stormwater for all of the projects parcels, especially the out
parcels, allowing them to be developed along the valuable highway frontage without
the need for their own onsite drainage pond. In addition, regional stormwater
management system can be utilized for roadway projects with an adjacent
commercial developments.
The development of regional stormwater ponds benefits both the County and the
development community by reducing the amount of land area required for a
stormwater system and releasing a larger portion back to the overall project area for
future development.
5-134
Infrastructure Element
Drainage Subelement
V.
GOALS, OBJECTIVES, AND POLICIES
Goal #9 - To develop a comprehensive stormwater drainage program including
design requirements, unified drainage plans, and protection of natural
drainage features and functions.
Level of Service
Objective 9.1
The Land Development Code shall contain requirements for
stormwater facility design and Level of Service.
Policy 9.1.1
The level of service for drainage plans and facilities for all new
nonresidential development, subdivision or planned development
is as follows:
1. For open basins - the retention of the first one-half inch of
runoff or a volume of 50 percent more for discharge into
OFW (water quality/pollution) and the 25-year, 24-hour
storm event (water quantity/flooding); Stormwater
discharges from any site shall conform to the water quality
standards used by SWFWMD, DEP and the rules and
regulations adopted or implemented by the Citrus County
Board of County Commissioners.
2. For closed basins - the retention of the first one-half inch
of runoff or a volume of 50 percent more for discharge into
OFW (water quality/pollution) and the 100-year, 24-hour
storm event (water quantity/flooding). No stormwater
runoff shall be allowed to drain directly through any
sinkhole or other karst feature. Stormwater discharges
from any site shall conform to the water quality standards
used by SWFWMD, DEP and the rules and regulations
adopted or implemented by the Citrus County Board of
County Commissioners.
3. For all spring and spring run basins – all stormwater
discharges from any site shall conform to water quality
standards used by SWFWMD, DEP and the rules and
regulations adopted or implemented by the Citrus County
Board of County Commissioners.
If and when an interlocal agreement is enacted, the agreement will
supersede this policy.
Policy 9.1.2
The County shall ameliorate the future discharge of inadequately
treated stormwater runoff into waters and wetlands of the state by
requiring the following:
5-135
Infrastructure Element
Drainage Subelement
a. Redevelopment projects shall include water quality
treatment to the greatest degree possible to not exceed that
required for new development.
b. All other projects shall ensure that water quality treatment
for the first one-half inch of runoff be retained on-site, or in
the case of runoff entering any body of water designated an
Outstanding Florida Water (OFW), a volume of 50 percent
more shall be required. Stormwater discharge shall
conform to the standards used by SWFWMD, DEP and the
rules and regulations adopted or implemented by the Citrus
County Board of County Commissioners.
Policy 9.1.3
The County shall coordinate with the SWFWMD and FDEP to
create a single permitting procedure for addressing
stormwater/drainage requirements of new developments.
Policy 9.1.4
All stormwater management and drainage systems proposed to be
constructed in karst sensitive areas, areas with known sinkholes,
and areas with shallow depth to limestone bedrock, shall be
evaluated for the presence of sinkholes through appropriate
geotechnical testing. All proposed Drainage Retention Areas
(DRAs) shall be tested for the presence of cavities and voids
beneath them. DRAs and other stormwater storage and treatment
facilities, but not conveyance facilities, shall not be located over
unfilled voids.
Policy 9.1.5
If there is an existing or historic sinkhole on the proposed
development, or indication that a sinkhole may develop in the
future, then a detailed geological/geotechnical investigation shall
be required. This investigation must be conducted by a certified
geologist or professional engineer experienced in hydrogeology
and a report submitted to the County for consideration. The
geologic investigation shall be comprehensive enough that
recommendations for site planning, engineering design and
construction techniques may be made. The County shall approve
or deny development proposals based upon the scale of the
development and the hazards revealed within the investigation.
Policy 9.1.6
No stormwater structure or facility, other than stormwater swales,
shall be located over or adjacent to an existing sinkhole unless it is
determined by a certified geologist or professional engineer
experienced in hydrogeology that the area is safe and that there is
no subsurface connection that may cause contamination or damage
to the groundwater.
5-136
Infrastructure Element
Drainage Subelement
Objective 9.2
Citrus County will establish a program to ensure that drainage
facilities meet existing and projected demand throughout the
planning period, maximize the use of existing facilities, and
discourage urban sprawl by using drainage levels of service and
requiring development to retain stormwater on site and connect to
existing drainage facilities.
Policy 9.2.1
All development is required to connect to existing facilities, meet
drainage levels of service, and retain stormwater on site.
Natural Features and Drainage
High Recharge
Objective 9.3
The development of drainage facilities in areas of high recharge
shall incorporate pollutant and filter functions into site drainage
plans.
Policy 9.3.1
Basins, swales, and culverts shall be designed to protect
groundwater and surface water quality and quantity in all new
developments.
Policy 9.3.2
The Land Development Code shall contain minimum standards for
recharge of stormwater in areas of high recharge. Postdevelopment recharge volumes and water quality shall equal or
improve historical pre-development conditions as provided by the
standards used by the SWFWMD, DEP and the rules and
regulations adopted or implemented by the Citrus County Board of
County Commissioners.
Policy 9.3.3
The County is exempt from pollutant and filtering functions in
cases of emergency actions.
Policy 9.3.4
The County will adopt and require stormwater Best Management
Practices (BMPs) for all stormwater management systems located
in all areas of the County.
Natural Drainage
Objective 9.4
Natural drainage features shall be protected and included in Master
Stormwater Drainage Plans.
Policy 9.4.1
Natural drainage features shall be analyzed in all development
plans and measures to protect the natural drainage features will be
incorporated into the County Land Development Code.
5-137
Infrastructure Element
Drainage Subelement
Policy 9.4.2
A public or private stormwater utility, MSTU or other applicable
mechanism shall be adopted by 2007 to provide the financial basis
for stormwater master planning and retrofitting projects.
Stormwater Drainage Plans
Objective 9.5
The County shall implement stormwater master plans, emphasizing
facility capacity of drainage systems as the basis for a watershed
based approach to stormwater management. The County shall
utilize the report to Plan Oversight Committee from the
Stormwater Level of Service Convention Committee in
development of the master plans.
Policy 9.5.1
The County will coordinate and work with the SWFWMD to
develop comprehensive watershed master plans through the
mechanism of a Memorandum of Understanding (MOU). The
MOU will assist with the development and implementation of a
variety of flood prevention and control projects, water quality
projects, detailed flood plain analysis, and watershed modeling.
Existing Deficiencies and Coordination
Objective 9.6
The County shall correct existing drainage deficiencies identified
in the Five-year Drainage Improvements Plan, prevent future
discharge of inadequately treated runoff, and implement a program
to identify, prioritize, and correct drainage deficiencies.
Policy 9.6.1
The program to identify, prioritize, and correct drainage
deficiencies shall be coordinated with the preparation of Master
Stormwater Drainage Plans and shall include measures to correct
system capacity, pollution loading, and recharge functions of
drainage systems.
Policy 9.6.2
The program to implement the correction of existing facilities shall
follow the schedule in the Capital Improvements Element.
Policy 9.6.3
Proposed capital improvement projects will be evaluated and
ranked according to the following level guidelines:
Level One - whether the project is needed to protect public health
and safety, to fulfill the County’s legal commitment to provide
facilities and services, to preserve or achieve full use of existing
facilities, or if permitted capacity has been reached.
5-138
Infrastructure Element
Drainage Subelement
Level Two - whether the project increases efficiency of use of
existing facilitates, prevents or reduces future improvement costs,
provides service to developed areas lacking full service, or
promotes infill development.
Level Three - where the project represents a logical extension of
facilities and services within a designated service area.
Policy 9.6.4
The County will continue a program to coordinate the expansion or
extension of drainage facilities with other local governments to
meet future needs.
5-139