CHAPTER 2 WATER QUANTITY EVALUATION 2.1 WATER QUANTITY MODELING 2.1.1 Model Used The computer modeling software packages RUNOFF (Huber and Dickinson 1992) and EXTRAN (Roesner and Dickinson 1992) were used to simulate stormwater runoff and transport fiom the drainage basins and through the drainage facilities of the Primary Storm Water Management Systems (PSWMS) which are the major ditches and canals that comprise the Nova Canal system. These modified programs are parts of the USEPA Stormwater Management Model (SWMM) originally developed for EPA by Camp, Dresser & McKee. The RUNOFF block of the SWMM program generates a discharge hydrograph interface file fiom watershed input information that is routed by the EXTRAN block through a network of conveyance components (culverts and ditches) representing the drainage system. -- 2.1.2 Limitations of Results The interpretation of the results and output of any computer modeling activity must take into account the reliability and the level of accuracy of the input data used to prepare the input files. The model should be calibrated using actual data from a measured storm event, whenever possible. For this study area, no existing streamflow data was available. To obtain stream flow data, continuous recording gauging stations were established at the two major outfds for the system, 1 lth Street Canal and Reed Canal, and daily stations at other locations within the Nova Canal system. Unfortunately, no major storm events occurred during the period of measurement and this data was not used to calibrate the model. The model as developed and calibrated by MPA closely reproduced the results obtained by other modelers for portions of the Nova Canal system. For calibration, the results of the model were also
Transcript
CHAPTER 2
WATER QUANTITY EVALUATION
2.1 WATER QUANTITY MODELING
2.1.1 Model Used
The computer modeling software packages RUNOFF (Huber and Dickinson 1992) and
EXTRAN (Roesner and Dickinson 1992) were used to simulate stormwater runoff and
transport fiom the drainage basins and through the drainage facilities of the Primary Storm
Water Management Systems (PSWMS) which are the major ditches and canals that comprise
the Nova Canal system. These modified programs are parts of the USEPA Stormwater
Management Model (SWMM) originally developed for EPA by Camp, Dresser & McKee.
The RUNOFF block of the SWMM program generates a discharge hydrograph interface file
fiom watershed input information that is routed by the EXTRAN block through a network
of conveyance components (culverts and ditches) representing the drainage system.
--
2.1.2 Limitations of Results
The interpretation of the results and output of any computer modeling activity must take into
account the reliability and the level of accuracy of the input data used to prepare the input
files. The model should be calibrated using actual data from a measured storm event,
whenever possible. For this study area, no existing streamflow data was available. To obtain
stream flow data, continuous recording gauging stations were established at the two major
outfds for the system, 1 lth Street Canal and Reed Canal, and daily stations at other locations
within the Nova Canal system. Unfortunately, no major storm events occurred during the
period of measurement and this data was not used to calibrate the model. The model as
developed and calibrated by MPA closely reproduced the results obtained by other modelers
for portions of the Nova Canal system. For calibration, the results of the model were also
Content Manager
Note
Note: This is only Part 2 of 3 of the Nova Canal System Watershed Management Plan: Final Engineering Report.
compared to flood elevations recorded during Tropical Storm Gordon, which occurred in
November 1994, the conditions of which were documented by MPA.
2.1.3 Input Used From Previous Modeling Efforts
The hydrologic and hydraulic parameters used in the MPA Nova Canal system SWMM model
were developed fiom information obtained fiom inventories conducted by Marshall, Provost
& Associates and data available fiom other studies of the system. Some parameters were
derived fiom previous studies performed by the City of Daytona Beach (CDM, 1989), City
of Port Orange (QLH, 1990), Volusia County (CDM, 1994), the City of South Daytona
(McKim and Creed, 1994), and the City of Holly Hill (Holly Hill Public Services Department
and D.M. Martin, 1992) which were verified before inclusion. Other parameters were
developed as original input information and was based upon field and other data.
The Nova Canal system and its drainage basin was first modeled in conjunction with the
8 Stormwater Master Plan prepared for the city of Daytona Beach. (CDM, 1989) The study
-- area for that report and the study area for this report are approximately the same. The areas
within and directly adjacent to the City of Daytona Beach (i.e., those lands north of Reed
Canal and south of 1 lth Street Canal) were investigated with greater detail than the areas
outside of the two discharge canals, areas in which most of the unincorporated areas of the
watershed are located.
Consultants for the City of Port Orange prepared a stormwater master plan that investigated
the drainage areas located south of Herbert Street that drain to Rose Bay through the
Halifax Canal (QHA, 1990). The Port Orange study focused on the major road crossings
contained within the City, including Dunlawton Boulevard, Commonwealth Boulevard, and
Nova Road. For SWMM modeling purposes, the large drainage basins in the QHA study
were divided into smaller areas by MPA.
At the time of preparation of this report, the City of South Daytona was in the midst of a
study to evaluate the drainage conditions in the City (McKim and Creed, 1994). The portions
of the unpublished study available for use in this investigation included a revised definition of
the drainage basins within South Daytona, and modification of some of the flow path
directions relative to the on@ Daytona Beach study. The South Daytona investigation also
included updated runoff coefficients. The revised drainage basin limits and the revised runoff
coefficients were used in the MPA evaluation.
In a similar manner, a drainage study by the City of Holly Hill was used to establish the basin
configuration north of 1 1 th Street (Holly Hill Public Services Department and D.M. Martin
1992). The drainage basins indicated in the study were compared to those in the original
Daytona Beach study. Revisions to the original drainage basin limits were made as required
for this study.
Some other drainage modifications have been made since some of these studies were
0 conducted and these changes were included in the SWMM model for this study. Due to
. . changes since the Holly Hill study, drainage structures were re-inventoried and verified for
use in the SWMM model. The construction plans for improvements that have been hnded
by Florida Department of Transportation (FDOT) for Nova Road were also utilized as
described in 2.1.6.
2.1.4 Topographic Information
The topographic information used in this investigation was as follows:
1. United States Geological Survey (USGS) Quadrangle maps, which provide five-foot increment contour information;
2. A topographic survey prepared by Abrams Aerial Photogrammetry in 1983 that includes the City of Daytona Beach, the City of Holly Hill, the City of Ormond Beach and some of the unincorporated portions of Volusia County (Abrams, 1983);
3. A topographic survey prepared by Abrarns Aerial Photogrammetry in 1981 that includes the City of Port Orange (Abrams, 198 1);
4. Construction plans prepared by the FDOT for Nova Road improvements; and
5 . Drainage construction plans prepared for developments in municipalities within the Nova Canal System Watershed.
2.1.5 Hydrologic Modeling (RUNOFF)
The RUNOFF block of the SWMM model was used for hydrologic modeling. The runoff
volume and the stormwater discharge hydrograph were computed for each sub-catchment or
sub-basin in the study area. A sub-catchment or sub-basin is defined as a discrete drainage
area described by common characteristics. The discharge hydrograph fiom a sub-basin was
computed by the model by routing the volume of rainfall through the sub-basin to the point
of discharge into the canal system (PSWMS).
@ Existing and hture impervious areas in the various sub-basins were identified using 1990
-- SJRWMD Geographic Information System (GIs) land cover data. The present land cover
GIs file was reviewed using aerial photographs, and land use modifications that occurred
since 1990 were included in an updated existing land cover file.
The drainage basins used in the Daytona study were compared to the basin definitions
provided by the other municipalities and FDOT in the area, and were modified to reflect
current conditions as described previously in 2.1.3. The topographic information previously
described was used as a basis to compute certain input data used in the computer model.
This calculated information consisted of drainage basin slope, basin width, drainage divides
and basin area. The RUNOFF block generates an interface file used by the EXTRAN block
t o simulate the hydraulic condition of the network representing the drainage system. The
hydrologic parameters used in the computer model are listed in the Appendix, and are
discussed in detail in Section 2.2.
2.1.6 Hydraulic Modeling (EXTRAN)
The EXTRAN block of the SWMM model was used to model the conveyance system which
transports the runoff The discharge hydrographs at the collection points generated by
RUNOFF are used as input to the EXTRAN program. The EXTRAN computer program
uses one-dimensional unsteady flow equations to model the flow through the stormwater
system (Roesner and Dickinson 1992). The EXTRAN model created for a stormwater
system can include pipes, open channels, weirs, orifices, pumps, storage basins and outflow
structures.
Topographic map and field survey information were also used in the EXTRAN block. The
topographic information was used to calculate the stormwater flood storage within each
drainage sub-basin for input to the model. The existing contours were digitally evaluated
using computer code written by MPA to determine the available storage in each basin. This
storage information was modifled where necessary to reflect the development that has
@ occurred since the topographic survey was completed. The inventory of drainage structures
from other studies was verified for this investigation and all new facilities were surveyed.
Modifications to the existing drainage system were included to account for the FDOT
construction projects related to the widening of Nova Road (SR 5A). All of the currently
funded FDOT projects were included in this investigation. Funded projects are those that
either are under construction or will be constructed with hnds available this year. An
example of an area under construction during the period of this study is the Nova Road
widening project recently completed in Holly Hill from 3rd Street north to Flomich Avenue.
An example of a h d e d project that has not been completed is the section of Nova Road from
Herbert Street to Beville Road which is scheduled to be bid October 1995. The model
considered all of the hnded projects as if they already have been constructed.
There are also fbture unfunded improvements that are scheduled to be constructed in the
Nova Canal basin that could have a sigmfkant impact to the drainage pattern, including the
widening of Nova Road at Herbert Street south to US 1. This construction activity was not
includedin the model since it may not be constructed.
The hydraulic parameters used in the model are discussed in detail in Section 2.3.
2.1.7 Water Quantity Model Schematic Layout
The hydraulic and hydrologic parameters were combined to prepare a SWMM model
schematic layout. Figures 2-la and 2-lb present the sub-basin layout utilized in the model.
The Nova Canal system watershed contains many small stormwater systems, which drain to
the main reaches of the Nova Canal. However, due to model limitations, and the intended
scope of this study, the hydraulic network used in the model did not include detailed
information about these small drainage systems. Lnstead, only the h t i n g structures within 0
..,. the systems in these areas were modeled. In cases where several pipes were discharging fiom
- the same area to the main canal, they were combined and modeled as equivalent pipes.
2.2 HYDROLOGIC PARAMETERS
2.2.1 Hydrologic Unit Areas
The initial hydrologic unit areas were derived as described in 2.1.3. The final boundaries were
verified using topographic information and field investigations. The history of the hydrologic
units, called basins, is presented briefly below.
The earliest found definition of the drainage basins, after the establishment of the Halifax
Drainage District and the initial overall watershed limit, was prepared by the FDOT as part
of their responsibility for the maintenance of Nova Road and the adjacent canal to the
roadway. The contributing drainage basins to the main reach of the Nova Canal were first
defined by FDOT with the widening of Nova Road fiom Volusia Avenue to Brentwood
Drive. (FDOT, 1970) The limits of the drainage basins created for this construction project
are reasonable illustrations of the current configurations.
The City of Daytona Beach Stormwater Master Plan also delineated the drainage basin
boundaries (CDM, 1989). This comprehensive study was used to evaluate the drainage
situation in the City of Daytona Beach, but it did not address the water quantity problems that
may be found in other communities within the Nova Canal system watershed. The drainage
basins described in this study are similar to those described by FDOT. The study also did not
include the Nova Road Canal system watershed south of Herbert Street (Halifax Canal) or
the sub-reaches of the main drainage systems in the Cities of Holly Hill or South Daytona.
Within the City of Port Orange the hydrologic units that were defined were reviewed with the
City and verified in the field. Drainage basins within the City of Holly Hill were originally
@ established by the Holly Hill Public Services Department and D.M. Martin (1992). Their
-- study delineated the major drainage basins within the City of Holly Hill that contribute to the
Nova Canal system, but does not discuss any contributing offsite basins. MPA field verified
structures in Holly Hill.
The City of South Daytona provided the preliminary output of their draft stormwater master
plan that defines the drainage systems within the City (McKim and Creed, 1994). This study
modifies the basins that were defined previously by CDM according to more detailed local
information. These revisions were included in the MPA SWMM model after field verification.
2.2.2 Rainfall
Design storm ramfhll volumes fiom the St. Johns River Water Management District (SJRWMD, 1988)
were used in stormwater modeling. The mean annual, I 0-year, 25-year, and 100-year storms
of 24-hour duration were the design storms used to evaluate the performance of the conveyance
system. Table 2-1 is a list of the rainfall events and rainfall depths used in the SWMM analysis.
A rainfall hydrograph was developed by the RUNOFF block for these volumes using the Florida
modified rainfall distribution (SJRWMD 1993).
2.2.3 Infiltration Rates and Capacities
The RUNOFF block of the computer model uses the Horton equation to estimate the amount
of rainfall infiltrating into the soil. After computing this infiltration volume and subtracting
it fiom the precipitation volume, the computer program then calculates runoff volume for each
time step. The runoff hydrograph is then routed to a receiving junction.
Site-specific injiltration data was not available for any part of the study area. The infiltration
rate parameters were estimated usingthemore general characteristics ofthe various soil hydrologic
groups. The a t r a t i o n values used in RUNOFF were selected as described in the SWMM '!i .2 .,,';: . Q useis manual (Huber and Dickinson, 1992; and Camp Dresser & McKee, 1994). Table 2-2
-- shows the Wtration rates used in the SWMM model for the different hydrologic soil types.
Presented within the City ofDaytonaBeach Stormwater Master Plan (CDM, 1989) are calibrated
infiltration values for drainage basins within the City of Daytona Beach. The infiltration rates
estimated fiom hydrologic soil types compare favorably to the City of Daytona Beach infiltration
values.
The volume of rainfall that can injiltrate is usually assumed to be held as soil storage, and the
estimate of infiltrated volume depends on the assumed antecedent moisture condition of the
soil. The antecedent moisture condition is an indication of the amount of moisture that is present
in the soil profile prior to a storm event. The antecedent moisture condition affects both the
infiltration rate and infiltration volume in the soil (SJRWMD, 1993b). The average antecedent
moisture condition (AMCII) was used for the analysis ofthe design storm flood routing response.
Once the soil storage capacity has been reached, all rainfall becomes runoe assuming the on-surface
ponding volume has also been exceeded, as is usually the case. During Tropical Storm Gordon,
the antecedent moisture condition was more severe than AMCII, meaning there was very little
infiltration potential remaining in the soil and most of the precipitation went to runoff.
2.2.4 Overland Flow Parameters: Hydraulic Lengths and Slopes
The hydraulic length is the weighted average flow length to the receiving junction for the basin
which is the point of discharge into the drainage canal. The hydraulic length for each sub-basin
was determined using aerial topography developed by Abrams (1983) for the northern portion
of the basin, and aerial topography for Port Orange, also developed by Abrams (1981). Recent
construction plans for development after those dates were referenced where necessary. The
basin slope is the average topographic change over the previously defined hydraulic length.
It was also determined using aerial topography by dividing the net difference in elevation by
the hydraulic length.
-- 2.2.5 Impervious Area
The impervious area for each sub-basin was determined using the existing condition (1988-90)
land cover maps prepared in GIs format by VC and SJRWMD. These GIs maps were verified
usiig aerial photogrammetry. Each type of existing land cover was assigned a FLUCCS code.
Each FLUCCS land use category was assigned an impervious percentage. A weighted average
method was used to determine the impervious percentage of each sub-basin for use in the
computer modeling activity. Table 2-3 presents the impervious area considered for each land
use and FLUCCS code.
Directly connected impervious area @CIA) is also included in the RUNOFF program to account
for the effects of stormwater flowing directly into a drainage system and into the receiving
water. The RUNOFF computer program limits the user to one value for the percentage of
the impervious area which is directly connected, and this value was assumed to be approximately 25%.
2.'2.6 Stage-Storage Relationships
Water storage data for each of the drainage basins within the Nova Canal system watershed
area were developed using information obtained fiom the City of Daytona Beach Stormwater
Master Plan (CDM, 1989) and the topography developed by Abrams for the northern portion
of the basin (1983) and for Port Orange (1981). This information was used to develop a stage
storage relationship for each of the junctions in the EXTRAN model into which a hydrograph
fiom RUNOFF was discharged. This stage-storage relationship represents the available storage
within the sub-basin for flood waters.
2.3 HYDRAULIC PARAMETERS
2.3.1 Structures/Facilities
The hydraulic data for the culverts, ditches, storm sewers and control structures were obtained
from the previous studies (presented in 2.1.3), FDOT construction plans, and MPA field surveys.
This data includes fist-order elevations, lengths, and structure geometries. All structures were
considered to be in a clean condition for the evaluation of the design storms, and assumptions
ofthe Manning roughness coefficient were based on the canals being maintained and fiee of debris.
A field survey of the existing structures in the main canal revealed that approximately two feet
of debris or siltation has accumulated in the bottom of many parts of the channel. An evaluation
was also performed to model the flood response of the canal in the reduced capacity condition
due to siltation.
2.3.2 Equivalent Hydraulic Conduits
Equivalent hydraulic conduits were sometimes used in the EXTRAN model to either simplify
a set of parallel culverts of equal geometry, or artificially lengthen short culverts to stabilize
the model. This was accomplished by a procedure that ensures that the equivalent conduit
has the same hydraulic characteristics as the actual conduit or group of conduits.
2.3.3 Boundary Conditions
The boundary conditions for the Nova Canal system are the assumed elevations of the receiving
water at the Halifax River for 1 lth Street Canal and Reed Canal outfalls, and Rose Bay for
the Halifax Canal. The tailwater elevations for the outfalls were determined by calculating
the one-year still water elevation for each outfd fiom information in the Flood Insurance Study
for Volusia County, Florida (FEMA, 1990). The 1 0-year, 50-year, 1 00-year, and 500-year
still water elevations were presented in this document. The one-year still water elevation was ..(.
@ determined by regression techniques and then interpolated to the outfalls which are between
-- the reference still water elevation locations.
2.4 CALIBRATION AND VERIFICATION
A stormwater model is a representation of a real hydrologic and hydraulic system. There are
several different ways to calibrate and verify the results of a storm water model to ascertain
whether or not the model reasonably represents the response of the system to a storm event.
The most accurate way is to compare the discharge or stage predicted by the model to actual
stage and discharge data for the system, if they are available. Attempts were made to collect
field stage and discharge information. However, because of the above average rainfall of 1994
during the period of this study, the response of the Nova Canal system to a rainfall event could
not be accurately ascertained fiom the obtained field data.
A less accurate method is to compare the results of the SWMM model for portions of the study
area to the results of previous studies where the land use and hydraulic system have not been
sigmflcantly altered. This method must be used when adequate discharge data is not available,
as was the case with this study. However, the predictive ability of the model after calibration
was tested using real world data fiom Tropical Storm Gordon, and the model developed by
MPA was determined to simulate the actual situation adequately for a conceptual level of evaluation
2.4.1 Calibrating and Verifying: RUNOFF
The RUNOFF results were calibrated by comparison to results fiom previous studies. The
runoff rate (the ratio of inches of runoff to inches of rainfall) was compared for each storm
event to the runoff rate predicted for the same areas in previous studies. The runoff rate was
expected to be higher than the earliest studies, which were performed when the Nova Canal
system watershed was not as heavily developed, and about the same as the most recent study
done for the City of South Daytona. In areas where the results varied widely, the infiltration
@ rates were modified to calibrate the model, which is the accepted procedure.
2.4.2 Calibrating and Verifying: EXTRAN
The EXTRAN results were compared to the results of previous studies in the absence of actual
field information. Stage information predicted by the model was also compared to peak flood
stage information obtained during Tropical Storm Gordon. This information is particularly
usefil because Gordon was a large enough storm event to be similar to the storm events used
in the model. Approximately nine inches of rainfall fell in a 24-hour period during Gordon,
which is between a 10-year and 25-year event, but because of a very saturated antecedent moisture
condition, the volume of runoff that occurred during Gordon was comparable to the 25-year
modeled event. The areas flooded during Tropical Storm Gordon are shown in Figure 2-2.
2.5 WATER QUANTITY RESULTS
The present and future land use conditions were modeled for the Nova Canal watershed using
the mean-annual, 10-year, 25-year, and 100-year storm events of 24-hour duration for evaluating
the capability of the Nova Canal system to handle the volume and flow of stormwater runoff
that is generated. Examination of the peak stages for the PSWMS were the primary method
of determining the extent of flooding and the ability of the drainage ways to convey the necessary
flow to prevent flooding. In the areas with the worst known flooding - those areas that violated
the Level of Sewice (LOS) criteria - Mher analysis of the model output data was undertaken
to determine the cause and extent of flooding. The following is a discussion of the model results
for each of the planning areas. In most casesthere was little difference between the existing
and future flood profiles due to the almost "built-out" condition of most of the watershed, and
the h r e use of stormwater management in new development. Therefore, the hture condition
will only be discussed where it deviates significantly from the existing condition.
*..,. 0 %.. . The runoff results for this study were compared to other studies of the Nova Canal watershed,
and the results of this comparison are shown in Table 2-4. As this table shows, the early studies
of the canal primarily used small storm events to design ditch and culvert sizes and predict the
flooded areas. As acceptable flooding levels changed over time, the desired level of protection
increased, and the effect of larger storms was investigated. This is reflected in the 1989 study
by CDM and this study. Combined with the increase in the drainage area from 6,700 acres
in 1922 to 12,200 acres today, the increase in the level of development clearly shows the capacity
problem that the Nova Canal system experiences.
2.5.1 11th Street Planning Area
The major drainage ways within the 1 lth Street Planning Area include the Calle Grande Canal,
Nova Road Canal North, Railroad Canal North, Railroad Canal South, and 1 1 th Street Canal.
The flood profiles showing the modeled performance of the system for these reaches of the
canals are shown in Appendix B, and are discussed below. Throughout this section, the mean-annual
and 100-year storms events are described. Both of these events are always of 24 hour durations.
The Calle Grande Canal flows south through western Holly Hill, starting just north of Arroya
Parkway, and ending at the discharge of this sub-reach in the 1 lth Street Canal. The water
elevations in this Canal are primarily influenced by the tailwater condition predicted in the 1 1 th
Street Canal. The predicted upstream flood elevation was less than 0.5 feet higher than the
outlet for all of the modeled design storm events (Figure 1, Appendix B). Flood elevations
for the 100-year event range fiom 7.5 to 8.0 feet NGVD, and fiom 5.0 to 6.0 feet NGVD for
the mean-annual event.
The Nova Road Canal North sub-reach is the most significant contributor of flow to the 1 1 th
Street Canal outfall. This portion of the Nova Road Canal flows north to the discharge point
into the 1 lth Street Canal, and receives runoff from the sub-basins along Nova Road from Volusia
Avenue at the southern end of the reach to 1 lth Street at the northern end of the reach. In
t; Li. 8 the area west of the Nova Road Canal North, the ridge is relatively steep and contributes a
. - sigmficant volume of runoff to the canal. The southern end of the reach is within Daytona Beach,
and has flood water elevations ranging fiom more than 10.0 feet to slightly less than 9.0 feet
NGVD for the 100-year event, and from 8.0 feet to 7.0 feet NGVD for the mean-annual event.
The northern end of the reach is within Holly Hill, and has flood water elevations fiom slightly
less than 8.0 to almost 9.0 feet NGVD during the 1 OO-year event, and fiom 6.0 to 7.0 feet NGVD
for the mean annual event. This means that any property which has the elevation of the ground
surface below these elevations would experience flooding during the referenced event. The
flood profles for this area are shown in Appendix B in Figures 4 and 5 for the existing condition
and Figures 4a and 4b for the fbture condition.
The Railroad Canal North flows south along the western side of the FEC railroad north of 1 1 th
Street, and discharges into the 1 lth Street Canal. The head loss that occurs in this canal is
about one foot for the 100-year storm event and about 0.5 feet during the mean-annual event
for the 100-year storm. This means the elevation of the water surface of the canal rises by
one foot over its length. The water surface profle is steady throughout this reach, and no single
structure causes an excessively large head loss in this Canal. From the profle results, it appears
the largest factor influencing the water surface elevations in the Railroad Canal North is the
tailwater conditionin the 1 1 th Street Canal, which ranges fiom 5.0 feet NGVD for the mean-annual
event to 6.5 feet NGVD for the 100-year event at the point of discharge of the Railroad Canal
North to the 1 lth Street Canal. The flood profiles for this Canal are shown in Figure 2 and
2a of Appendix B.
The Railroad Canal South flows north along the western side of the FEC railroad and discharges
into the 1 lth Street Canal at the same location as the Railroad Canal North. This Canal has
similar conditions as the Railroad Canal North as it experiences a moderate and steady head
loss (rising water sdace over its length), but is also most strongly influenced by the tailwater
conditions in the 1 1 th Street Canal which are presented above. The flood profle for this Canal
is shown in Figures 3 and 3a in Appendix B.
-- All ofthe above canals flow into the 1 lth Street Canal. This Canal is the primary outfall to
the Halifax River for the northern half of the watershed. Because of the large volume of flow
contributed by the Nova Road Canal North reach and the additional flows fi-om the other smaller
ditches discharging to thls Canal, a large head loss is experienced through the entire reach of
the 1 lth Street Canal during all ofthe modeled storm events. The outfall for all of the storms
was set at the one-year still water elevation of 2.6 feet NGVD. The surface water elevation
reached at Nova Road, the upstream end ofthe reach, varied fiom 6.2 feet NGVD for the mean-annual
event to 7.7 feet NGVD for the 100-year event. The flood profiles for the 1 lth Street Canal
are shown in Figures 6 and 6a.
2.5.2 Airport Planning Area
The Auport Planning Area has one major canal that was modeled, known as the Navy Canal.
This reach flows southeast fiom the Volusia Mall to a crossing culvert under Clyde Morris
Boulevard, then east to the discharge point into theNovaRoad Canal Central reach along Museum
Road. At the point of discharge the water level elevations range is predicted to be 9.1 feet
NGVD during the 100-year event, and 7.5 feet NGVD during the mean-annual event. From
here the water surface elevation rises sharply to Clyde Monis Boulevard where the Navy Canal
flows through the Atlantic Coastal Ridge to the lower elevation area near the Museum of Arts
and Sciences. At the Auport, which is the upstream end ofthe system, the water surface elevations
are estimated to reach approximately 29 feet NGVD for the 100-year event, 27 feet NGVD
for the 25-year event, 26 feet NGVD for the 1 O-year event, and 23 feet NGVD for the mean-annual
event. Because of the large slope of the Canal coming off of the ridge, the velocity and flow
rate in the Navy Canal in the lower reaches is excessive and capable of causing erosion. The
flow profiles for the Airport Planning Area are shown in Figures 7 and 7a in Appendix B.
- 2.5.3 Reed Canal Planning Area
The reaches of the Nova Canal system within the Reed Canal Planning Area include the Nova
Road Canal Central, Nova Road Canal South, Stevens Canal, and Reed Canal. The flood profiles
for the existing and future conditions for these canals are shown in Appendix B, as Figures 8
through 12 in Appendix B.
The central reach ofthe Nova Road Canal begins at the drainage divide at Lnternational Speedway
Boulevard (US 92) and flows south to discharge into Reed Canal. This reach has a relatively
constant rise in the water surface elevation from Reed Canal to the drainage divide. This reach
flows through Daytona Beach at the northern end and South Daytona at the southern end.
According to the model, the stages inDaytona Beach are the highest ranging fiom about elevation
9.0 feet NGVD to 10.0 feet NGVD for the 100-year event, and from 7.0 feet NGVD to 8.0
feet NGVD for themean-annual storm. Despite the high elevations, limited flooding is experienced
in Daytona Beach because of high ground elevations in the area surrounding the canal, typically
greater than elevation 9.0 feet NGVD. The portion of the canal flowing through the City of
South Daytona was predicted to experience water surface elevations ranging from 8.0 feet
NGVD to 9.0 feet NGVD for the 100-year event, and fiom 5.0 feet NGVD to 7.0 feet NGVD
for the mean-annual event. The flood proflles for the Nova Canal Central are shown in Appendix
B in Figures 8 and 9 for the existing condition and Figures 8a and 9a for the hture conditions.
Nova Road Canal South flows north fiom Herbert Street to discharge into Reed Canal at the
intersection of Reed Canal Road and Nova Road. This reach contains several relatively small
pipes in comparison to the larger box culverts located along other portions of the Nova Road
Canal. These smaller pipes hct ion well during the mean-annual, 10-year, and 25-year storm
events, but become completely filled and begin to surcharge during the 100-year event. During
the smaller events, the water elevations at Herbert Street are only about one-half foot higher
than the elevations at the discharge point into Reed Canal, with stages reaching 5.6 feet NGVD
*;; 0 during the mean-annual event, 7.1 feet NGVD during the 10-year event, and 7.7 feet NGVD
-- during the 25-year event. During the 100-year event however, the head loss between Herbert
Street and Reed Canal Road is more than one foot due to the small culverts and the stages
at Herbert Street reach close to 9.0 feet NGVD. Flood profiles for Nova Road Canal South
are shown in Figures 12 and 12a in Appendix B.
Stevens Canal is a local drainage feature that drains the portion of City of South Daytona just
west o m . S. Highway No. 1 and south ofI3eville Road into Reed Canal. Stevens Canal experiences
a high head loss, which causes more than a 3-foot rise in water surface during the 100-year
event, and almost a 2-foot rise in water surface for the mean-annual event. This large head
loss is a result of a high volume of runoff that is routed through Stevens Canal and the inability
ofthe Canal to handle it. There are several large contributors to Stevens Canal including a directly
FDOT design for culvert sizing for canal adjacent to Nova Road.
56%
66%
2.9"/24 hr
5.3"/24 hr
SWMM Computer Model
SWMM Computer Model
CHAPTER 3
POLLUTANT LOAD EVALUATION
3.1 GENERAL
The hydrologic cycle begins with and is driven by rainfall. When rain falls onto the landscape, it
already contains inorganic chlernicals. Precipitation on the landscape can infiltrate, begin overland
flow, evaporate or be utilized by vegetation. During overland flow, additional inorganic and organic
materials become dissolved and suspended in the flowing water. Precipitation that infiltrates to
become subsurface groundwater flow can also accumulate nutrients and organic acids that are leached
fiom the soil. In the Nova Canal system, overland flow (stormwater runoff) and subsurface flow can
discharge into the drainage canals and then be transported into the Halifax River and Rose Bay, with
the accumulated materials.
The Halifax River is the ultimate receiving water for both stormwater runoff and groundwater from
@ the Auport, 1 lth Street Canal, Reed Canal and Eastside Planning Areas. Rose Bay is the receiving
water for flows fiom the Halifax Canal Planning Area. Between storms in the wet season, and during
the dry season, water flow in the canals is due to draining of the surficial aquifer. In the natural or
pre-development situation, there were no creeks or rivers discharging into the Halifax River between
the Tomoka River and Rose Bay. Instead, precipitation that did not infiltrate to the surficial aquifer
moved slowly over land to the Tomoka River or to Rose Bay, the materials in the flows being
assimilated along the way by swamp, freshwater marsh, flatwoods, and mesic hammock vegetation.
Stormwater runoff pollutants are materials proven to be hamhl to receiving waters, which, in the
case of the Ha.Uax River and Rose Bay, are estuarine systems. Urban stormwater runoff pollutants
can be nutrients,, oxygen demanding materials, suspended solids, and toxic materials. Since the
watershed is urbanized, the discharge from the Nova Canal system contains elevated levels of these
constituents after a storm. Nutrients can cause algae in the water column to increase. The direct and
indirect effects of algal growth include oxygen consumption during decomposition, turbidity
increases, sediment accumulation, and shading. Oxygen-demanding wastes can reduce the dissolved @ oxygen concentration of the water to levels that can cause stress or death to fish and shellfish.
Particles in suspension in the water column of various sizes, called suspended solids, can cause
turbidity that reduces sunlight penetration, and can cause sediment accumulation which can physically
smother benthic communities. Metals and synthetic organic chemicals, such as pesticides and
solvents, can have an effect on plant and animal growth by causing toxic responses.
Stormwater pollution is usually considered on an area-wide basis, and these loads are called non-point
source pollutant loads. By contrast, point source pollutant loads are generated over a smaller area,
an example of which is a wastewater treatment plant. In both cases, the ultimate discharge may occur
at a discrete point. Because this watershed is urbanized, the loads from Nova Canal system
watershed can be characterized as urban non-point source loads.
In order to assess the level of non-point source pollution to the receiving estuaries, the loads of
certain pollutants were estimated for existing and hture land use conditions. The following pollutant
@ loads were estimated: Total Nitrogen (TN), Total Kjeldahl Nitrogen (TKN), Total Phosphorous (TP),
Orthophosphorous (OP), Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Biochemical
Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Zinc (ZN), Lead (Pb), Cadmium (Cd),
and Copper (Cu). A computer model was used to combine land use, hydrologic, and pollutant
loading parameters to estimate existing and hture pollutant loads, as described below.
3.2 PESM MODEL
A model has been developed by the SJRWMD in order to estimate the relative magnitude of mass
loadings of non-point source pollutants for a set of distinct drainage areas. This model is called the
Pollution Load Screening Model (PLSM) (Adarnus and Bergman, 1993). For this watershed
management plan, the model was applied to the sub-basins of the Nova Canal System watershed,
using input information developed by SJRWMD and MPA. Pollutant loads generated by the PLSM
model runs were found to be comparable to pollutant loads calculated from tributary water quality
0 considerations (concentrations) for all contaminants except suspended solids (Marshall, 1993).
The PLSM model utilizes land use, soil type, and rainfall to estimate annual and area-based pollutant
loads. This GIs based model uses ARC/INFOm software with the GRID" module to perform the
evaluation by intersecting basin physical characteristics to create a database that contains the
combined acreage of each type of land use with soil type and rainfall. The model then uses the
created database to calculate pollutant loadings using unit loading factors. Land use and soil types
within the Nova Canal system watershed have been previously discussed in the physical features
section of this report.
3.3 INPUT DATA AND ANALYSIS
The pollution situations of both present and fiture land use conditions were simulated by the model.
The present land use condition was established using existing land cover maps developed in GIs
format by SJRWMD for 1988-1990. The hture land use condition was developed fiom the Volusia
@ County Comprehensive Plan, combined with SJRWMD data. The Florida Land Use and Cover
Classification System (FLUCCS) land use codes fiom the existing and fbture land use information
were reduced to ten general land uses for pollutant generation calculations. The general land use
categories used in the model are:
- Low density residential (LDR); - Medium density residential (MDR); - High density residential (HDR); - Low intensity commercial (LC); - High intensity commercial (HC); - Industrial (I); - Agriculture (AG); - Mining (M); - Recreationlopen space (RO); and - Natural areas (NA).
Table 3-1 lists the FLUCCS codes and Table 3-2 lists the general land use categories with FLUCCS
codes. Each land use has specific pollutant generation characteristics.
@I Because the current information available for pollutant loadings required the consolidation of similar
land use types into one of the ten general land use categories, the PLSM model is limited to
comparison of the model output on a watershed-wide, or regional planning area basis. As such,
individual sub-basin loads cannot be compared.
Soil types were separated into the six hydrologic groups. Each hydrologic soil group has a specific
stormwater runoff potential, with "A" soils exhibiting the lowest runoff potential and highest
infiltration capacity and "D" soils exhibiting the highest runoff potential and lowest infiltration
capacity. The dual classification soils, "AD" and "B/D", exhibit a lower runoff potential when
drainage improvements are constructed in the area (USDA, SCS 1986). This means that certain " D
soils will drain like "A" or "B" soils with drainage improvements in place and a positive outfall
available. However, to achieve this, the elevation of the surficial aquifer has to be reduced, which
is accomplished by discharging groundwater into the estuary. Because the worst case condition
occurs when the tides are in the high range of elevations and the ground is saturated, all areas with
"AID" or "B/D" soils were assumed to have runoff characteristics similar to "Dm soils. The runoff
@ coefficients by soil type used in the model are presented by Table 3-3. The quantity of pollutants
generated by a specific area is directly proportional of a hydrologic soil group.
The annual normal rainfall determined by SJRWMD was used in the analysis to determine the yearly
pollutant loading (Rao et. al., 1990). The annual normal rainfall in the study area varies fiom 48 to
49 inches per year. The volume of rainfall used to complete pollutant loads in the Nova Canal
watershed was 48 inches.
After runoff coefficient values are assigned by the model, the annual runoff volume for a specific area
is calculated by multiplying the annual precipitation by the assigned runoff coefficient. Then, the
pollutant mass loading rates were applied. The pollutant mass loading rates utilized for this study are
presented in Table 3-4. This mass loading rate was then multiplied by the annual runoff volume to
generate the potential annual load for each land uselsoil type category within a particular sub-basin.
The resulting mass loadings for each category within each sub-basin were summed to develop the
total annual loads from that sub-basin, as well as the composite annual land use load per acre. In
order to apply the model, it was assumed that all areas of the same land use/soil type category have
the same pollutant loading. The loading rates used for these assessments represent an average
condition for a stochastic set of events.
Stormwater treatment facilities constructed with more recent developments were taken into account.
For the existing land use case, only the developments that have been constructed in the last 10-15
years have been subject to stormwater management permitting requirements. Approximately 10%
of the existing land use in 1990 was considered to have stormwater management practices that would
reduce pollutant loadings (ECFRPC, 1990). In certain sub-basins, this 10% figure is probably low.
For example, the commercial area at the intersection of Nova Road and Dunlawton Avenue in Port
Orange (Halifax Canal Basin) was developed mostly after 1980, and many of the commercial
development have stormwater management facilities which were required. By contrast, in some of
the residential areas of Daytona Beach, this figure is probably high. Overall it was considered to be
a reasonable estimate.
For the model, stormwater treatment efficiencies were assumed for those developments with
stormwater management facilities based upon values reported in the literature. The stormwater
treatment system removal efficiencies assumed for the model are listed in Table 3-5. The removal
efficiencies are based upon information compiled by Wanielista and Yousef (1993). These
conservative removal efficiencies represent average values for systems that have been on-line for
several years.
Assumptions were also made regarding the future land use condition, which represent the "build-out"
situation. Where an existing urban land use was shown by the fbture land use plan to be different than
the existing land use designation for that location, the existing land use was assumed to remain. Ten
percent of all of the existing land use areas in 1990 were assumed to have stormwater treatment in
the future condition. All future development was assumed to be subject to stormwater management
regulations, and the treatment efficiencies for managed systems (Table 3-5) were applied for all fkture
Q . - development. The fhture condition does not include any retrofit of existing areas with stormwater - . . - - treatment systems. Since hture development is expected to have treatment systems, much of the
hture load will be contributed by existing developments without treatment facilities.
The output from the PLSM model was used to generate total annual and composite area-wide
stormwater pollutant loads for each sub-basin of the Nova Canal system watershed. In order to
evaluate impacts, comparisons were made by planning area and by constituent within a planning area,
on both the basis of total loadings and on loadings generated per unit area of land surface.
3.4 MODEL RESULTS - ESTIMATED POLLUTANT LOADS
3.4.1. Total Annual Loads
The estimated total annual loads by region for both the existing and the fhture land use condition for
each drainage basin are presented in Table 3-6. The sum of the loads for the Airport and the Reed
@ Canal drainage basins is also presented, as this sum represents the mass of material that is being
discharged fiom the Reed Canal outfall. In a similar fashion, the loads presented for the 1 1 th Street
Canal, all of the Eastside Planning Areas, and the Halifax Canal represent the mass of material
discharged from those outfalls.
It can be seen that loads for the 1 lth Street Canal and the Reed Canal Planning Areas are similar for
the existing land use conditions, with the 1 Ith Street Canal loads slightly higher for all constituents.
When the contribution fiom the Airport Planning Area is added to the Reed Canal Planning Area, the
mass of material from these combined areas is somewhat higher than the mass from the 1 1 th Street
Canal Planning Area. The Eastside Planning Areas are smaller in area than the others, which is
reflected in smaller total annual pollutant loads. The Halifax Canal Planning Area has existing loads
that are comparable to the Airport Planning Area. Therefore, for the existing condition, the highest
pollutant loads are being discharged fiom the Reed Canal outfall followed by the 1 lth Street Canal
outfall, the Halifax Canal outfall, and the four outfalls of the Eastside Planning Area.
For the future land use condition, also as shown in Table 3-6, the Reed Canal Planning Area had
slightly higher loads than the 1 lth Street Canal Planning Area for all parameters. The future loads
are only slightly greater than the existing situation, reflecting the fact that the Nova Canal watershed
is already approaching "build-out". Similar to the existing condition the highest pollutant loads are
discharged into the Halifax River by the Reed Canal system outfd, which is greater that the 1 lth
Street Canal outfall.
The increase in loads in the hture conditions are compared by basin in Table 3-7. It can be seen that
all pollutant loads increase slightly in the hture, except for lead. Annual loadings from lead are
expected to decrease in the future because gasoline for cars is now required to be unleaded. The
increases are generally seen to be in the 0-30% range, which is indicative of an area that is already
relatively highly urbanized, has a large area of type " D soils, and in which there is not a large amount
of remaining area available to be developed. Only in the Reed Canal Planning Area is there much land
for any appreciable future development. The developed nature of the Nova Canal system watershed
requires that retro-fit best management practices for existing development be implemented to reduce
1 nonpoint source loadings to the Halifax River and Rose Bay.
3.4.2 Area-based Loads
Table 3-8 presents the area-based pollutant loading rates by basin, expressed as lb/ac on an annual
basis. This measure of pollutant loading is a measure of the intensity of the loading. For the existing
condition, several of the small, highly developed basins of the Eastside Planning Area have the most
intense existing loading rates. Of the larger basins, the Airport and the 1 lth Street Canal Planning
Areas have similar loading rates and are the highest, followed by the Reed Canal and Halifax Canal
Planning Areas. The low loading rate of the Wilder Boulevard basin is a result of the large area of
that basin in a golf course development. However, with the exception of the Eastside Planning Area
basins, the existing land use condition loading rates are similar for the larger basins. This reinforces
the concept of the homogeneity of the Nova Canal watershed.
8, For the h t u r e land use condition, all area-based pollutant loads increase slightly, except for the
Bellevue Avenue outfall basin, which is almost built-out in the existing land use condition.
Additionally, some of the metal loading rates, particularly lead, decrease in the fhture land use
condition.
TABLE 3-1
FLORLDA LAND USE AND COVER CLASSIFICATION SYSTEM (FLUCCS)
100 URBAN Residential, low density Residential, med. density - 2-5 dwellingslacre Residential, hgh density Commercial and Services - trailer parks, condos and motels 146 Oil & gas storage 147 Mixed commercial and services 148 Cemeteries 149 Commercial & services under construction Industrial 15 1 Food processing 152 Timber processing
1523 Pulp and paper mills 153 Mineral processing 154 Oil & gas processing 1 5 5 Other light industrial 156 Other heavy industrial
1 56 1 Ship building & repair 1562 Pre-stressed concrete plants (includes 1564 Cement plants) 1563 Metal fabrication plants
Estrac live 161 Strip mines
1611 Clays 1612 Peat 16 1 3 Heavy metals
162 Sand & gravel pits (must be active) 163 Rock quanies
1630 Limerock or dolomite 1633 Phosphates 1634 Heavy minerals
164 Oil & gas fields 165 Abandoned mines (if water-filled = 530) 166 Reclaimed = returned to natural condtion 167 Holding ponds (holds mining wastewater) Institutional 173 hhlitary 175 Governmental - (Use 170 for city halls, courthouses, police stations, office builhgs, post
oflices) Recreational 1 8 1 Swimming beach 182 Golf courses 183 Race tracks 184 Marinas & fish camps 185 Parks and zoos 187 Stadiums - facilities not associated with hgh schools, colleges, or universities Open land 192 Inactive land with street pattern but no structures
8 TABLE 3-1 Continued
FLORIDA LAND USE AND COVER CLASSIFICATION SYSTEM (FLUCCS)
200 AGRICULTURE 2 10 Cropland and pastureland
2 1 1 Improved pastures (monocult, planted forage crops) 2 12 Unimproved pastures 2 13 Woodland pastures 2 14 Row crops 2 15 Field crops 2 16 Ivbxed crop - used if crop type cannot be determined
220 Tree crops 22 1 Citrus goves 224 Abandoned tree crops
7 10 Beaches other than swimming beaches 720 Sand other than beaches 730 Exposed rocks 740 Disturbed land - use level Il classfication, code for w a l land in transition, fill areas, burned-areas
742 Borrow areas - associated with nearby fill areas for construction 743 Spoil areas
811 Axports 8 12 Railroads 8 1 3 Bus and truck terminals 8 14 Roads and highways (divided 4-lanes with medians) 8 15 Port facilities 8 16 Canals and locks 8 18 Auto parhng facilities - when not dnectly related to other land uses 8 19 Transportation facilities under construction
820 Communications 82 1 Mcrowave towers
830 Utilities 83 1 Electrical power facilities 832 Electrical power transmission lines 833 Water supply plants 834 Sewage treatment plants 835 Solid waste disposal 839 Uuhties under construction
(') - Marshall, McCully & Associates, 1994 (2) - Associated Technology and Management, 1994 (') - Camp, Dresser and McKee, 1994 (')- Mean valves for entire watershed, present land use conditions (') - Described as "dissolved phosphorous"
Banier Island
Turnbull Creek'4)
Basin 1, DeLeon Springs Area
Rural Resid., Residential
Natural, Undeveloped, Some Resid.
5.2
4.4
3.8
3.3
0.8
0.8
0.4")
0.43'''
84.2
84
450.7
426
23.1
27.9
184.8
209
0.01
0.005
0.09
0.065
0.02
0.014
0.00
0.002
:c I 551 WII~OII Jones Company
CHAPTER 4
ANALYSIS
4.1 GENERAL
In this chapter, the results of the water quantity and quality evaluations are analyzed and the
appropriate stormwater management improvements for the identified problem areas are presented.
The cost for each of the appropriate improvements is also estimated. Before presenting this detailed
information, general information about stormwater management improvements - which can be
structural, non-structural, and operation and maintenance (O&M) - is presented.
4.2 STORMWATER MANAGEMENT IMPROVEMENTS
Stormwater management improvements can be structural, non-structural, or operation and
maintenance (O&M). Structural improvements are typically capital improvement items with a -
purpose of correcting an existing problem, while non-structural improvements can include a variety
of activities but are usually considered to be policy-oriented. Operation and maintenance is typically
considered to be the day-to-day operation and upkeep of the function of the facilities. General
information about the structural, non-structural, and O&M improvements is presented below.
4.2.1 Structural Improvements
Structural improvements for water quantity problem areas have the objective of reducing or
eliminating flooding that is affecting or has the potential to affect a public or private structure, or a
roadway. Structural improvements for water quality problem areas have the objective of reducing
the pollutant loads. Whenever possible, structural improvements are designed to reduce flooding with
an associated improvement in the water quality of the receiving water. The design and construction
of stormwater improvements for the Nova Canal system watershed should integrate water quantity
and water quality considerations, including a reduction in freshwater discharges to the Halifax River.
Typically, the largest scale of stormwater improvement is a regional treatment facility. These facilities
are designed to receive stormwater runoff fiom many areas with different owners. A regional facility
is most cost effective when it is placed in a relatively undeveloped area to minimize the purchase of
the land. Due to the extent of development in the Nova Canal system watershed and the lack of
elevation difference, large regional facilities will be difficult to site. In the Nova Canal system
watershed, there are few, if any, tracts of land large enough and located in the right place for regional
facilities. Ifthere were, the ddliculty in piping the outlying existing subdivisions to a regional facility
makes regional facilities expensive. CDM (1989) evaluated regional facilities for the City of Daytona
Beach, but the prohibitive costs has kept them from being implemented.
Stormwater management system design (other than regional facilities) is driven in most of Florida
today by the requirements of the water management districts. Most of them have adapted design
criteria for specific system types that presumably result in a stormwater management facility that
achieves at least the minimum 80% removal requirement of the State Water Policy (17-90).
However, information in the literature as the result of research efforts presents a somewhat different ..hi 0 picture. It appears that most of the systems in common use for stormwater management may not be
meeting that goal.
The stormwater management facilities most commonly used in Florida are dry retention areas, swales,
exfiltration trenches, and wet detention ponds. Dry retention areas, swales and exfiltration trenches
allow infiltration of stormwater into the soil and are typically used in Type "A" soils (well-drained)
that are not limited by water table conditions. Wet detention ponds have open water and hold
stormwater for a prescribed period before releasing it. Wet ponds are typically used in higher
groundwater table areas. Each of these systems is discussed in more detail below.
Dry retention areas are used to retain stormwater on site and to recharge captured runoff to the
surficial aquifer, and subsequently to the Floridan aquifer. Dry retention areas treat primarily
suspended particles but also convert some dissolved pollutants, and are inexpensive in comparison
with other stormwater management practices. To operate successfUlly, retention areas need favorable
soils. The disadvantages of dry retention areas are that they are land intensive, but that land can often
be utilized for other purposes such as park areas. The least expensive and most hnctional retention
areas utilize existing grade and natural vegetation. As Table 4-1 shows, dry retention areas are an
efficient practice for most constituents. Dry retention areas are also effective in reducing volumes
and peak rates of runoff.
Swales are shallow, linear dry retention areas typically located adjacent to roadways and designed to
transport stormwater and infiltrate it while it is transported. Swales with swale block can reduce rates
and volumes of runoff and pollutants. They hold water for short periods after a storm event and are
aesthetically pleasing when properly designed. Swales can only be used on areas with moderate to
very good soil infiltration characteristics. Table 4-2 shows that swales are not as efficient as dry
retention, and removal efficiencies are variable according to the constituent.
Exfiltration systems are underground rock galleries with perforated pipes that store and infiltrate
stormwater into the ground. To utilize an exfiltration system, the soil must be highly permeable (usually'
soil type "A") and the seasonal high water table must be deeper than about three feet below existing
grade. Exfiltration systems are commonly used in commercial and industrial areas where space is limited
and land area valuable. The disadvantages of exfiltration systems include high initial installation and
replacement costs, and limitations in areas of high water tables. Exfiltration systems can have
applicability in retro-fit situations to achieve source reduction in existing developments in Type "A"
soils because, like swales, exfiltration trenches can be installed within the existing right-of-way. Table 4-3
shows that exfiltration trenches have an efficiency that is almost comparable to dry retention areas.
Wet detention pond systems are typically used where soil infiltration rates are limiting and the water
table is high. Wet detention ponds have a permanent pool for treatment and a temporary flood control
volume. The permanent pool provides for extended treatment of stormwater pollutants. The temporary
flood control volume detains runoff fiom a storm event to attenuate the peak discharge. Water is
released from the pond by a control structure such as a weir when the permanent pool volume is
excessed. Wet detention ponds require an accurate estimate of the seasonally high water table elevation
pJ which varies from year to year and may be difficult to determine in coastal areas. Table 4-4 shows
that the removal efficiency of wet ponds varies widely between the presented constituents.
A treatment technology that is currently being evaluated for use in urbanized watersheds is the treatment
train. A treatment train involves the use of several treatment processes in series operation to achieve
the efficiency of treatment that may not be available from any single practice. Treatment trains could
include swales, dry retention, exfiltration systems, and wet detention ponds though treatment trains
originated as alternatives to these practices in highly developed areas. Examples of unit processes
that have been used in treatment trains include bafne boxes for sediment removal, petroleum absorbents
in catch basins, oiVwater separators and cyclone separators. They are typically installed at the end
of the collecting pipe near the point of discharge. Ln a highly urbanized basin with a high percentage
of DCIA, the treatment train may be a viable alternative. However, frequent maintenance will be required
for any treatment train system because of the inherent limited storage. Unfortunately, very little
information regarding efficiency is found in the literature and most claims of efficiency made by
manufacturers have not been sufficiently proven by scientific study. (fJ
4.2.2 Non-Structural Improvements
The range of non-structural best management practices is very broad, including any method of water
quantity and quality protection that is not a physical stormwater management structure or the operation
and maintenance (O&M) of these structures. Non-structural stormwater management controls can
most simply be labeled as either regulation or information. These two general categories include
regulation of land use, construction activities and maintenance, and information for public education
and community awareness.
Governmental regulations currently exist in various forms and methods applicable to this study, as
described in Chapter One. These regulations are administered by numerous agencies at different
governmental levels of jurisdiction. For this report an analysis was performed as to what can be
.". ::. Q accomplished at the local City or County level within the study area and, accordingly, local ordinances
were reviewed and examined for applicability for this purpose.
Land use controls exist at various levels of specificity. The County's Comprehensive Plan contains
goals, objectives, and policies for existing and future land use to be implemented by the more specific
land development regulations. The County and City Zoning Ordinances set guidelines by more definite
land use standards, and the County and City Land Development Codes provides even more explicit
requirements through various methods of planning and construction, all toward attaining the ideals
of the Comprehensive Plan.
The most directly applicable regulations are the various stormwater management ordinances pertinent
to the study area. These regulations have the dual purposes of flood protection and water quality
protection. Flood protection is accomplished by many methods, some of which are mandated by the
County's participation in the Federal FIRM program, such as requiring minimum elevations for roads
and buildings. Requiring compensatory storage of displaced flood water volume is another such flood'
0 .I :. protection method to protect against inappropriate development within the flood plain. Unfortunately,
the results of this study indicate that the Federal Emergency Management Agency (FEMA) flood plain
maps do not adequately represent the areas within the Nova Canal system watershed that may be
susceptible to flood damage, as witnessed by Tropical Storm Gordon, and confirmed by the output
of the Nova Canal system watershed SWMM model. From the information obtained in this study it
is apparent that governmental jurisdictions in the Nova Canal system watershed that do not have 100-year
flood compensation regulations as well as a minimum finish floor above the 100-year peak stage should
be immediately implement regulations using the elevations established by the SWMM model for the
100-year event, as confirmed by previous studies and the impact of Tropical Storm Gordon (about
a 25-year event).
Other "non-traditional" revisions to the current Land Development Regulations could also provide
sigmiicant benefits for water quality protection. For example, reducing paved parlung requirements
for certain commercial uses and replacing these areas with grassed overflow parking (with no net
Q reduction in the total number of spaces) would reduce the stormwater volumes generated and decrease
pollutant loads. This reduces the amount of DCIA and avoids concentrations of stormwater volumes
and pollutants. Another example would be the deletion of the current allowance for groundwater
lowering in the City and County stormwater management standards thereby reducing hture freshwater
runoff flows to the Halifax River.
Public education is also a non-structural control which seeks to attain voluntary compliance with water
quality protection methods, by enlightening residents to the benefits and consequences of their actions.
One existing effective tool in this effort is the County-sponsored HalifdIndian River Task Force.
This group provides the general public with information concerning the positive and negative effects
of various methods of maintenance, fertilizerlpesticide applications, solid waste collection and
disposal, etc. The Halifdndian River Task Force has the goal of water quality improvement and,
towards that end, conducts clean-up activities that allow interested citizens to obtain hands-on experience
with water quality protection.
Volusia County Environmental Management Department currently operates a program called Enviro-net,
in which a network of concerned volunteers are trained to perform various monitoring activities in
support of on-going programs. Volunteer networks have proven .to be successhl because not only
is data being gathered, but also because citizens have the opportunity to learn about the watershed
and its receiving waters first-hand, and pass this knowledge on to others.
Other obvious avenues for environmental education include the development of information regarding
stormwater management in the form of video presentations, advertising on local television stations,
information packets specific to the study area, etc. Citizens of the watershed should be made hlly
aware of the benefits provided, and the threats that exist ifimprovements are not put in place, particularly
if they are going to stand behind the expenditure of stormwater utility hnds for structural or non-
structural improvements. A monthly newsletter for this purpose has been used successfblly in many
other stormwater utilities in Florida.
@ 4.2.3 Operation and Maintenance Improvements
From the field observations made for this study it is apparent that the primary ditch system of the Nova
Canal system requires maintenance to bring the capacity of the system back to the design condition.
The types of activities that are required are the removal of siltation that has accumulated in the open
ditch and in the culverts. In most areas it appears that the canal has not been cleaned or dredged since
the initial construction of the system. Based on SWMM modeling results, the canal flood stages are
an average of 6 inches higher during a minor storm (10-year, 24-hour) event because of the lack of
proper maintenance. Regrading the existing drainage canals to their original elevations will improve
the overall hydraulic performance of the system.
After the system has been cleaned to keep it working at its optimum, the following operation and
maintenance procedures have been suggested (CDM, 1991):
1. Canals, ditches, culverts and ponds should be kept clean and clear of debris.
2. Grassed areas in and around stormwater canals should be mowed periodically to prevent woody growth, and allow access by maintenance vehicles.
3 . Canals should be prevented f?om becoming a nuisance to residents by expelling odors or providing mosquito breeding grounds.
4. Stormwater systems should be inspected periodically to check for needed cleaning and structure repairs or replacement.
5. Accumulated sediment should be removed periodically, and never allowed to occupy more than 10% of a pond, culvert, or other stormwater facility.
Table 4-5 presents typical operation and maintenance activities for stomwater systems. Table 4-6
presents the typical desired level of service for operation and maintenance activities.
If a stormwater management system is not periodically maintained, the system will eventually fail in
controlling both water quality and quantity. For an inadequately maintained system, the cost of
replacement of a failed system will exceed the cost of maintenance. Figure 4-1 shows how the level
8 of maintenance affects both quality of service and cost. This figure is accurate for most public utilities
projects and can help determine the scheduling of system maintenance. Maintenance costs remain
relatively low during the first 75% of estimated lifetime, or time to failure. Costs then increase rapidly
after 75% ofthe system life has passed. A one dollar cost for maintenance at 75% of facility life to
restore the facility to as-new condition increases to four dollars at 87% of facility life. Maintenance
should be performed before the facility reaches the point where cost and quality begin to deteriorate
rapidly. Table 4-7 presents representative costs for stormwater system maintenance, at approximately
75% of facility life compared to replacement costs. Poorly maintained stormwater systems result in
increased liabilities, citizen discontent, and increased health risk (Eighmey, 1992).
4.3 WATER QUANTITY PROBLEM AREAS
4.3.1 General
Water quantity problem areas are deiined as areas that experience periodic flooding to the extent that
@ property damage could occur or an evacuation route could become unpassable. For roads and
homes/businesses, these are areas that do not meet the previously outlined level of service (LOS) criteria.
The water quantity problem areas identified by this study are considered to be impacts to the public's
health, safety and welfare and are not "nuisance" areas of standing water. In most areas of Florida,
standing water historically has occurred for periods of several days to six months during most years.
In coastal Florida, standing water is a common occurrence.
The SWMM model was used to evaluate the existing drainage inf7astructure in the Nova Canal system
for adequacy to protect the existing roadways or buildings from flooding during design storm events.
Typically, the water elevation from the model at a particular structure is compared to the existing
elevation in the area ofthe structure to determine the extent of flooding. The level of service (LOS)
criteria presented in Chapter 1 is the measure of acceptability of the depth and duration of flooding.
The LOS criteria can also be used to set the minimum acceptable elevation of new roadways and to
determine areas where improvements are needed to attain a more acceptable LOS. The design storms
used for this LOS evaluation are the mean annual, 10-year, 25-year, and 100-year, 24-hour events
which are the commonly used standards for coastal regions.
W e the SWMM model of the Nova Canal system allowed for an analysis of the existing drainage
system to be performed with respect to specific situations and storms, other information about the
drainage system and the watershed area allowed other more general observations to be made. From
the topographic, geographical and vegetational community information, the Nova Canal system
watershed can be categorized as a tidally iduenced coastal flood plain valley between two relict shoreline
ridges. Under natural conditions this area periodically experienced standing water which sometimes
remained for extended periods. The Nova Canal system was constructed in an attempt to relieve these
conditions. While some development within a coastal flood plain such as this is considered to be a
reasonable beneficial use of the land, the density of urban development that has taken place has
exacerbated the impacts of this periodic flooding by adding a large area of impervious surface, and
housing more residents that can then impacted. Additionally, the seasonal effects of the tide elevation
range does not appear to have been taken into account when the acceptable level of development in
this flood plain was established.
Typically, the FEMA flood insurance rate maps are the source used to determine the extent of the
100-year flood. However, the SWMM model results in this study indicates that the elevation of the
100-year flood and the extent of predicted flooding are much more extensive than are shown on the
FEMA maps. Perhaps the reason lies in the use of a riverine flood model instead of a hydrologic model
such as SWMM, or the lack of detailed topographic information utilized to determine the extent of
the flood, or both. This problem was also identified in the City of Daytona Beach Master Plan, but
FEMA has not to date adopted the flood elevations presented in the Daytona Beach report. Even
so, the City of Daytona Beach does use the 100-year flood elevations predicted by CDM (1989) for
minimum construction standards.
The Nova Canal system was originally constructed to promote agricultural development. The original
design, as best can be ascertained, allowed for standing water in the agricultural areas that the drainage
0 system was intended to promote. The canal system was not originally designed for urban development
and the associated impervious area. One consequence is that the increased impervious area has increased
the volume of runoff that the agriculture drainage system is required to handle. This caused higher
flood stages and on even wider extent of flooding. Ln simple terms, development has occurred in many
places in this watershed where it was not originally intended.
As an added problem, many of the residents of the existing developments have not lived in the coastal
plain long enough to experience the effects of high water tables, high tides and high rate and volume
rainfall events that periodically occurs in the Nova Canal system watershed. The technology of drainage
cannot assure that naturally occurring flood conditions can be alleviated during all possible storm events,
and periodic flooding should be expected in any coastal flood plain.
The evaluations performed for this study show that there are few alternatives available to alleviate
the flooding problems. The remaining vacant land is limited and the retro-fit facilities that are described
below for each planning area attempt to take advantage of these few remaining parcels. Certain- / .:, . Q s imcant , undeveloped parcels that can provide flood storage are also considered for acquisition or
protection fiom future development. The types of alternatives analyzed include:
1. Small improvements for specific problem areas,
2. Stormwater attenuation and infiltration on the sandy ridge west of Nova Road,
3. Larger treatment facilities on vacant properties vacant to the canals, and
4. Additional outfalls with no net increase in discharge.
5 . Purchase of some of the remaining undeveloped parcels to keep fiom making the problem worse.
Previous studies outlined various recommendations and improvements to the flooding conditions found
in the basin. Most of the recommendations that were made in other studies were included in the analysis
and are discussed as they apply in each planning area.
8 4.3.2 Canal Maintenance
The main reaches of the Nova Canal system was constructed in the 1920's. The records that are available
indicate that the there have been no major maintenance activities performed on it since it was constructed.
A limited survey of the existing canal indicated that some of the major drainage structures have serious
obstructions that limit flow. The average depth of the siltation in the drainage structures that were
investigated is about two feet. Additionally, partial blockages were observed in some of the canals
north of 1 lth Street and in the Halifax Canal. Siltation and blockage was also observed in the Nova
Road Canal structures.
To evaluate the potential effect of canal maintenance, the Nova Canal system was evaluated using
the SWMM model specifically to analyze the effect of maintenance. An adequately maintained condition
is defined as all drainage structures being able to flow full without obstructions. An un-maintained
condition as modeled herein is defined as all drainage structures having a decreased capacity due to
siltation, blockage or collapse. For the model, the assumed amount of blockage or siltation was two-
feet on the bottom of the canal or drainage structure. Using the SWMM model of the canal system,
the 10-year, 24-hour storm was routed through the maintained and un-maintained system configurations.
The results of the routing showed that during this storm event the water levels in the un-maintained
canal system could stage as high as the 1 00-year, 24-hour storm event levels for a maintained canal
system configuration. In most cases the un-maintained system produced stages at least as high as the
25-year, 24-hour storm event level in a maintained canal. As another comparison, the un-maintained
condition produced stages that were between 0.5 and 1.0 feet higher than the 10-year flood level in
a maintained canal. The flood profiles are shown in Figures 4G through 14G in Appendix B.
From the results of this modeling effort, it appears that returning the canal system to the origtnal design
section and cleaning the existing culverts will result in lower peak flood stages for the entire canal system
of about .05 feet. The estimated cost for the relatively large-scale canal maintenance activity is shown
in Table 4-8, and is about $2 million.
0 4.3.3 11th Street Planning Area
In the 1 lth Street Planning Area, there are many locations that experience nuisance flooding, even
on small rain events. In Holly Hill, for example, there are areas where the topography is so flat that
water ponds during an average wet season storm. In Tropical Storm Gordon, many local roads in
this planning area were impassable for a time. However, since the evacuation roadways (U.S. Highway
No. 1 and Nova Road) are built at relatively high elevations, the evacuation routes in this planning
area appear to be adequately protected. Some homes were flooded in this area during Tropical Storm
Gordon, but not to the extent of flooding experienced in the Reed Canal planning area. A level of
service analysis was performed for this planning area and violations of the LOS criteria are shown in
Table 4-9.
The 1 lth Street Canal discharge reach was evaluated for LOS violations. Nuisance flooding in areas
adjacent to this canal occurred during Tropical Storm Gordon, but no LOS violations were identified
by the model. The 1 1 th Street Canal receives flows fiom the surrounding canals, the Nova Canal ~ o r t h , '
. . 3..
52.: 0 the Calle Grande Canal, the Railroad Canal Nonh, and the Railroad Canal South. As such the tadwater
conditions in the 1 I t . Street Canal affect flood stages in the other reaches and sub-reaches. Flooding
that occurs in other canals can often be attributed to a high tailwater elevation in the 1 lth Street Canal.
The 1 lth Street Canal is already flowing at maximum capacity, and increasing the discharge capacity
is not an option due to limited right of way and permitting restrictions. Fortunately, no areas in violation
of the LOS were identified that are caused by the overflow of the 1 lth Street Canal. Due to the high
flows and volumes of storm water, the construction of detention ponds along the 1 lth Street Canal
have little impact on reducing the stages in the 1 lth Street Canal, unless they are extremely large.
Because of this, no water quantity improvements alternatives were identified for the 1 1 th Street Canal.
The northernmost reach that discharges into the 1 lth Street Canal is the Calle Grande Canal. At the
upstream end of the Calle Grande Canal is the Riviera Oaks Subdivision which is the most sigmilcant
problem area in the 1 lth Street Planning Area. From the model results, the elevations at the upstream
end of the Calle Grande Canal reached an elevation of 8.0 feet NGVD for the 100-year event. This -
0 exceeds the f i s h floor elevation of approximately 20% ofthe homes within the Riviera Oaks Subdivision.
During the 25-year event flood stages reach approximately 7.6 feet, which still results in the flooding
of a couple of houses. This area experienced severe flooding during Tropical Storm Gordon. The peak
flood elevation as a result of the Tropical Storm Gordon event was estimated to be over 9.0 feet NGVD.
This is approximately one foot higher than the 100-year flood elevations predicted by the SWMM
model. Some of this difference may be attributed to decreased canal capacity by silt and debris. Three
alternatives were evaluated to solve the flooding problems there.
The first alternative considered for flood protection within Riviera Oaks Subdivision was rerouting
the runoff from this area. This alternative includes removing the subdivision drainage system from
discharging directly into the Calle Grande Canal and routing the runoff to an undeveloped area to the
north. A schematic diagram of this alternative is shown in Figure 4-2. Constructing a dike at the southern
end ofthe subdivision will route the stormwater coming fiom the west directly to the Calle Grande
Canal. This will also prevent runoff fiom the canal fiom flowing back into the subdivision. Runoff
fiom the subdivision can be routed to the north through two 48-inch culverts to a new retention area- 6 : .
conceptually located on some vacant land north of the subdivision. The pond was sized to hold both
the runoff fiom Riviera Oaks and the Arroya Parkway area. A required pond size of about ten acres
was estimated to be necessary to prevent house flooding during the 100-year event. Results fiom the
model with these improvements in place showed that the flood elevations in the Riviera Oaks Subdivision
reached 7.1 feet during theJ00-vear Storm event. This would result in some road flooding on Rio Way,
but would not result in any flooding of houses. For the 10-year event, with the improvements in place - the flood elevations reached 6.3 feet NGVD, which protects both the roads and houses fiom flooding.
An outfall will need to be provided for the pond connecting it back to the Calle Grand Canal. This
connection should have a bacldlow preventer, for occasions when the elevations in the Calle Grande
Canal are high. For modeling purposes, however, it was assumed that no runoff could discharge to
the canal due to a high tailwater condition, thereby simulating the worst case. The estimated cost of
this improvement is $930,000 including land cost and is itemized in Table 4-10.
Another alternative is similar to the recommended improvements for the Riviera Oaks Subdivision *,::j
made in a previous study (CDM, 1987). This recommendation included the construction of a dike
to protect the subdivision and a stormwater pumping station to lower the flood elevations. This alternative
also included a stormwater treatment pond to the north of the property. The approximate 1995 cost
for this improvement is $1,500,000.
The third alternative explored for this problem area is the raising of the finish floor of the homes above
the 100-year storm event. The number of homes that have finish floor elevations below the 100-year
flood stage predicted by the SWMM model is 52. The estimated cost to raise a slab-on-grade house
including the associated site grading is about $20,000. The total cost to raise all of the 52 homes above
the 100-year storm flood elevation is $1,040,000. This construction will not solve the road flooding
and access problems during storm events, but will have the lowest annual maintenance cost.
The next reach investigated within the 1 1 th Street Planning Area is the Nova Road Canal North. The
flow profile for this reach is shown in Appendix B. Some local flooding is associated in the sub-basins' 0 draining to this canal during the larger storm events. This flooding predominately occurs in the City
of Holly Hill to the east of the Canal, and is primarily limited to road flooding with only isolated house
flooding. Several of the LOS violations shown in Table 4-9 are located along this Canal reach. Two
of the violations are along Nova Road, but each has less than 0.5 feet of flooding, and flooding only
lasts for a couple of hours. The 10-year local road violations along this Canal are on 2nd Street and
Madison Avenue. One alternative previously identified by others for this reach was the construction
of an additional outfall into the Halifax River for Nova Road Canal at North Street through a water
quality detention pond. When this alternative was modeled on SWMM, this alternative lowered the
peak flood stages in Nova Canal at the point of connection, but had little impact on elevation in the
canal more than a half mile from the connection with the new outfall. The estimated 1995 cost for
this improvement is $28.6 million dollars. The predicted flood profile for the 100-year event for this
alternative is shown in Figures 4C and 5C in Appendix B.
In the Railroad Canal North, flooding is experienced up to an elevation of 7.4 feet NGVD during the 'i.-.i 0
100-year event under existing and future conditions. While some roads are flooded under these conditions,
only isolated house flooding occurs. During the 10-year event, Walker Street and 8th Street were
roads identified by the model to be in violation of the LOS. However, there are other local streets
that cross the canal in this area, so the flooding of these roads is not considered to be a major problem.
The elevations in this canal are primarily controlled by the tailwater condition in the 1 lth Street Canal,
and any improvements along the Railroad Canal North would have little impact on the flood elevations.
Therefore, no alternatives for structural improvements were identified along this reach.
The Railroad Canal South has s i d a r conditions to the Railroad Canal North, in that flood stages reach
about 7.6 feet NGVD during the 100-year storm event. These are the result of a high tailwater condition
in the 1 lth Street Canal rather than inadequate drainage capacity. Therefore, like the Railroad Canal
North, no structural improvements were evaluated.
Flooding was experienced along both the North and South Railroad Canals during Tropical Storm'
Gordon. Flood elevations in these areas reached an elevation of approximately 7.0 feet NGVD, which
is close to the predicted flood elevations for these canals during a 25-year storm event.
A drainage study performed for the City of Holly Hill (Holly Hill Public Services Department and
D.M. Martin, 1992) included much of the area within the 1 lth Street Planning Area. Recommendations
from this report primarily dealt with regrading of canal sections and replacing undersized culverts,
some of which were too small to be included in the SWMM model. The study described the effects
ofthe 1 1 th Street Canal tailwater elevation on the other canal reaches located in Holly Hill. Improvements
to the 1 1 th Street Canal were recommended to be implemented prior to the reconstruction of any canals
located in Holly Hill. The primary improvement recommended for the 1 lth Street Canal in the Holly
Hill study is regrading (cleaning) the canal. The other recommendations in this report mostly include
the replacement of some existing metal culverts with concrete structures. The results of the MPA
investigation indicate that the maintenance and reconstruction of the ditches and culverts will provide
positive drainage impacts.
8 4.3.4 Airport Planning Area
Under natural (pre-development) conditions, the Auport Planning Area drained very slowly westward
to the upper Tomoka River. When the Daytona Beach International Airport was built by the Navy
in the 19401s, the ridge to the east of the Auport site was breached by the ditch system which discharged
into the Nova Road Canal at the current intersection of Museum Road. The ditch through the ridge
is called the Navy Canal. The Navy Canal also conveys groundwater that drains from the ridge into
the Navy Canal and then into the Nova Canal system, creating a base flow condition that continues
for long periods after storms and into the dry season. This groundwater discharge deprives the sudcial
and the Floridian aquifers of recharge waters. Even though potable supply wells for this area are now
located west of the study area and loss of recharge capability at this location may not impact potable
water supplies, this "mining" of groundwater removes the freshwater pressure that protects against
saltwater intrusion. This groundwater flow reduces the capacity of both the Navy Canal and this reach
of the Nova Road Canal but, in previous studies, was not even considered in the drainage assessments.
a The Navy Canal diverts floodwater that used to be relieved through the Tomoka River into the Nova
Canal system. This contributes to overtopping of the canal bank. Before development of the flood
plain occurred in the area between U.S. Highway No. 1 and Nova Road, the over toppiig of the banks
and flooding ofthe lowest-lying areas did not create a serious flooding problem. But the urban development
that has occurred has increased the impervious area, filled the natural flood plain storage, and placed
private property where floodwater naturally stood. Therefore, the flooding problems that occur near
the discharge of the Navy Canal into the Nova Road Canal are caused not only by diversion of floodwater
and groundwater base flow but also by the allowed intensity of urban development.
The Navy Canal is the only major drainage canal draining runoff from the Au-port Planning Area to
the Nova Canal system. Although the model shows that some flooding is predicted in the vicinity of
the airport, only existing vacant land in the eastern portion of the airport floods during the 1 OO-year
event. This was substantiated by the conditions that occurred during Tropical Storm Gordon, where
the runways and commercial buildings on the eastern side of the airport were dry while most of the
0 vacant land surrounding the runways became flooded. Since no property was predicted to be damaged
during the 100-year storm event, no specific problem areas were identified in the Aqor t Planning Area.
Museum Boulevard is the only road in this area whichviolated the LOS, as shown in Table 4- 1 1. However,
this roadway is not an evacuation route and the overtopping of this road provides for equalization
of storage for waters coming from the Navy Canal that would otherwise have to be conveyed by Nova
Road Canal, and is thus not considered a major problem.
The volume and peak flow rate of runoff predicted to be discharged into the Nova Canal system from
the w o r t Planning Area has the potential to have a negative impact on flood stages within the Reed
Canal Planning Area. To alleviate this impact, alternatives were examined to attenuate the peak flow
coming fiom the Navy Canal. A detention pond and detention areas dedicated for flood storage are
proposed improvements. Figures 4-3 and 4-4 show the location of the improvements and the extent
of temporary flooding. The combination of a flow control structure in conjunction with an additional
300 ac-ft of storase in the basin was found to reduce the stages in the Nova Road Canal at the Navy
Canal discharge point by about 0.5 feet and not significantly increase the area of flooding in the Airport-
@ Planning Area. This would cause ponding of water temporarily in areas below an elevation of 29 feet
NGVD, some ofwhich are not currently inundated under large storm events. This can also be accomplished
by excavation of areas above the ground water table but not as cost-effectively. The estimated cost
of the control structure, piping, and a storage basin is $2.7 million dollars and is itemized in Table 4-12.
Another improvement that will provide a lowering of the stage in the Nova Road Canal is the diversion
of additional flow fiom the downstream portion of Navy Canal to the low lying areas located west
of Nova Road and north and south of Museum Road. These improvements include the construction
of diversion culverts under South Street and Museurn Road to allow stormwater to flow to the existing
low areas. Some of these areas are already protected from development by a conservation easement
for a mitigation project. These areas will provide storm surge storage and also water quality benefits.
The limited existing development on the area should not be affected since building finished floor elevations
appear to provide adequate protection with the exception of some of the on@ buildings at the Museum
of Arts and Sciences. The area to the north of Museum Boulevard already floods during some storm
0 events, and would only provide water qualtty treatment for the Navy Canal during these events. The
estimated cost of this improvement is $2 10,000 and is itemized in Table 4- 13. Additional protection
in the form of berms around buildings with walkovers may also be needed which can be determined
by additional evaluations during the design phase.
4.3.5 Reed Canal Planning Area
Under natural conditions, water probably stood in the lowest parts of the Reed Canal Planning Area
for extended periods of time during an average wet season. The presence of Tuscawilla soils, still
evident in Tuscawilla Park in Daytona Beach and the remaining mesic hammock vegetation that still
exists to the south of International Speedway Boulevard confirm that these lands were naturally very
poorly drained. Most of the areas bounded by Nova Road and U.S. Highway No. 1EEC Railroad
is considered to be type " D soils, which indicated that the Soil Conservation Service did not consider
that these soils could have improved drainage characteristics, even with the installation of a drainage
system. Soils that can be improved with the addition of drainage improvements are typically classified
as "A/D" or "BID.
One reason for the poor drainage characteristics of this part of the Reed Canal Planning Area is the
presence of the Atlantic Coastal Ridge in a more predominant fiom than is expressed north of U.S. 92
(International Speedway Drive). he-elevations of the ridge in the western part of this planning area
are as high as 50 to 60 feet NGVD in many locations, but the ridge drops steeply to the east to elevations
of 10.0 feet NGVD and lower on the flat terrace. In certain area where ditches have been dug to convey
runoff fiom an existing development to the Nova Road Canal, groundwater can seep out of the ridge
into the ditch and contribute to the base flow in the Nova Canal System.
As discussed in the previous section, the Navy Canal contributes a significant flow to the Nova Canal
system and to the Reed Canal Planning Area. Therefore, before considering alternatives for improving
the conditions in this drainage basin, reductions to the flow fiom t h e ~ a v ~ Canal must be implemented.
8 Improvements in the Auport Planning Area will reduce the cost of improvements in the Reed Canal
Planning Area significantly.
Serious flooding occurred in the Reed Canal planning area during Tropical Storm Gordon. Several
subdivisions just to the east of Nova Road in South Daytona contained flooded homes. The City of
Daytona Beach also reported flooding in subdivisions east of Nova Road. It appears that the worst
flooding in the planning area occurred in the Big Tree Village subdivision in South Daytona. Most
of these areas were also predicted to flood by the SWMM model, and flooding in most of these area
violated the 10-year level of service (LOS) criteria. This means that this area is very susceptible to
flooding during almost any worse-than-average event. The LOS violations in the Reed Canal Planning
Area are listed in Table 4-14.
The Nova Road Canal Central is the northernmost reach of the drainage system in the Reed Canal
Planning Area. The northern portion of this canal (which flows through the City of Daytona Beach)
reaches peak flood stages of elevation 9.0 to 10.0 feet NGVD during the 100-year storm event. The
northernmost part of the canal reach is a closed culvert with the surrounding ground elevation generally
greater than 9.0 feet NGVD, and the finished floor elevations are generally above 10.0 feet NGVD.
The model also predicted flooding for the 100-year event in Daytona Beach at the intersections of
Nova Road and Volusia Avenue and Nova Road and Orange Avenue. These are also dips in Nova
Road which are predicted to experience flooding for about 2 hours during the 100-year event. Other
roads in the developed area to the east ofNovaRoad are also predicted to be flooded during the 100-year
event, and these are identified in Table 4-14. The southern portion of this reach flows through South
Daytona as an open channel, and the model predicted peak flood elevations of 7.0 to 9.0 feet NGVD
during the 100-year event.
In this part of the reach there are many places in South Daytona where the finish floor elevations are
below the predicted peak flood stages of 7.0 to 9.0 feet NGVD. There are also places where the ditch
bank that confines the Nova Canal system is below 7.0 feet. In particular, along Restanick Road, the canal
over-topped the ditch bank during Tropical Storm Gordon and contributed to severe flooding conditions
:+.:> 8 in the Big Tree Village subdivision. The City of South Daytona has maintained a temporary pump
at this location for the past several years, but this pump was not effective during Tropical Storm Gordon.
The Nova Road Canal Central reach which runs fiom Lnternational Speedway Boulevard to Reed Canal
Road was modeled assuming an as-built condition for improvements on Nova Road that are to be
constructed by the FDOT within the next two years between Herbert Street and Beville Avenue. The
construction drawings for this section of roadway show that the northbound lanes of Nova Road are
going to be located on the east side of the canal with the canal located between the north and southbound
tr&c lanes. The construction of the northbound lane on the east side of Nova Canal should act as
a dike that will keep the canal from overtopping the east bank and flowing into the low lying areas
in South Daytona. However, there is a potential for runoff generated by these lower areas to become
trapped behind the higher berm. Many local roads failed the 10-year LOS criteria under these conditions,
and they are identiiied in Table 4-14. A larger, permanent pump station is currently being considered
to remove trapped runoff. The cost for a pump station in the Big Tree Village subdivision utilizing
the existing Martin Paving Company borrow pit was estimated at $650,625, as shown on Table 4-15.
0 The improvements previously described in the Airport Planning Area are predicted to partially lower
the peak flood stages in the Nova Road Canal Central in northern South Daytona, but the model does
not show that they will lower stages between Big Tree Road and Reed Canal Road. To reduce the
water level in the Nova Road Canal in this area, a detention area located at the southwest comer of
Nova Road and Big Tree Road was modeled to receive runoff that flows fiom the west off the ridge
down Big Tree Road. A schematic diagram of this improvement is shown in Figure 4-5. This detention
area in conjunction with the Airport Planning Area storage reduced flood stages between Big Tree
Road and Reed Canal Road. When it was modeled, this detention area also prevented the flood stages
from getting high enough to overtop Nova Road once it has been widened between Herbert Street
and Beville Road. The estimated cost to construct the Big Tree Road detention facility is $2.2 million.
The itemized costs are listed in Table 4-16.
0 ... Even with the canal contained in its banks, the flood stages are still higher than many finished floor
elevations of many homes in the neighborhoods discharging into the Nova Road Canal Central in
South Daytona. To prevent the Nova Road Canal Central from backflowing into these neighborhoods,
backnow preventors can be installed at the end of the discharge pipes fiom the neighborhoods. Since
this d l increase internal flooding in these subdivisions it will also be necessary to construct a pumped
system that will relieve local flooding in each subdivision or group of subdivisions. The City of South
Daytona has proposed installing backflow preventors and a permanent pump station to replace the
temporary pump currently in place on Restarrick Road. The operation of the 25 cfs pump station was
modeled with SWMM to determine the effect of the additional water into the Nova Road Canal. The
results of the modeling effort showed that the pumped discharge into the Canal had negligible effect
on the stage in the system.
The Au-port Planning Area storage and diversion, the Big Tree Road detention facility storage, and
one-way valves on discharges fiom the existing subdivisions on Nova Road in South Daytona were
modeled concurrently for the Nova Central system. The backnow preventors caused the canal stage ("J
to increase over the existing condition, and served to negate any improvement gained by construction
of the Big Tree Road detention facility. However, the peak stages in the Nova Road Central Canal
reach (between Reed Canal Road and B e d e Road) did not overtop the FDOT proposed banks during
the 100-year storm event. These flood profiles are shown in Figures 8D, 9D, and 12D in Appendix B.
After evaluating upstream improvements, the Reed Canal reach of the Nova Canal system was analyzed.
Like the 1 Ith Street Canal, the water elevation in Reed Canal determines the tailwater conditions for
the other contributing reaches. According to the model, there are few problem areas adjacent to Reed
Canal. The only major problem is flooding of the property at the southeast comer of Nova Road and
Reed Canal Road, at the upstream end of Reed Canal. According to the model, the peak flood elevations
for this area reach 7.7 feet NGVD during the 100-year event. The ground elevations in this area are
around 5.0 feet NGVD. Few reasonable alternatives for improvements exist for this small area due
to the elevations that surround the property. An increase in the Reed Canal discharge would alleviate
this small flooding area, but it is not anticipated that such an increase would be allowed. Because of
0 the diculty in lowering stages in Reed Canal, flooding problems at this location can only be alleviated
with land use policy decisions rather than structural improvements. The existing land use facilities
where flooding occurs is industrial and includes a used auto parts facility and a truck repair and storage
area. Due to the potential for polluted runoff from these areas, these businesses should be encouraged
to relocate to higher areas where there is less of a possibility of effecting the W a x River. Estimating
the cost to relocate these businesses is beyond the scope of this report. However, purchase of this
parcel to provide a flood storage area would assure that this potential pollution source is eliminated.
Also contributing to Reed Canal is the Nova Road Canal South reach which runs from Herbert Street
to Reed Canal Road. Like the Nova Road Canal Central, the portion of this canal between Reed Canal
Road and Madeline Avenue is scheduled for improvements that include a road on both sides. The
SWMM model predicted that the 100-year flood stages in this area will range between 7.5 feet NGVD
and 8.0 feet NGVD. At these elevations the canal will not overtop the proposed FDOT improved
road. These elevations do, however, exceed the elevation of some of the surrounding areas discharging
to the Nova Road Canal, and back flow preventors were considered to be in place in running the model.. :*: :- 0 Runoff storage or pumping will need to be implemented on a site specific basis in the developments
which cannot adequately handle the ponding runoffwhich occurs when the back flow preventors are closed.
The portion of the Nova Road Canal South reach south of Madeline Avenue wdl not have any portion
of Nova Road to the east of the canal. Despite this, the existing banks are at least elevation 10.0 feet
NGVD for the reach south ofMadeline Avenue and the maximum flood stages in this area do not exceed
9.0 feet NGVD during the 100-year event. As such, the banks of the canal will not be overtopped
in this area.
Similar to the Railroad Canals in Holly Hill in the 1 lth Street Canal Planning Area, Stevens Canal was
dug to alleviate the flooding in the area just west of the ridge that exists along U.S. Highway No. 1
between Beville Road and Reed Canal Road. Only about one-half of the length of Stevens Canal is
within a dedicated right-of-way or easement. According to the SWMM model, the stages in Stevens
Canal reach an elevation of approximately 8.5 feet NGVD at Beville Road and an elevation of 8.0 feet
+: ' NGVD at Big Tree Road during the 1 00-year event. At these elevations, Stevens Canal has the potential to
overtop its banks north of Big Tree Road, an area identified as a 10-year LOS violation in Table 4-14.
This canal is presently limited by the existing conveyance capacity. Increasing canal capacity between Big
TreeRoad and Reed Canal Road can reduce headloss in the canal and reduce the upstream flood elevations.
The improvements modeled for the Stevens Canal area include doubling the width of Stevens Canal
between Big Tree Road and Reed Canal Road, but keeping the existing pipes. This was shown to
reduce the head loss in the Stevens Canal reaches, while the peak discharge into Reed Canal will only
increase slightly because the final culvert will not allow much additional flow. To compensate for this
additional flow for regulatory purposes, Stevens Canal was modeled with a connection to the Martin
Paving Company shell pit near Nova Road to provide peak flow attenuation storage and water quality
treatment. The estimated cost to construct these improvements is $1.5 million. The itemized construction
costs are listed in Table 4-17. The flood profile for this canal is shown in Figure 11E in Appendix B.
Other studies have been completed to help resolve some of the flooding problems in the Reed Canal
Planning Area. The City of Daytona Beach study (CDM, 1989) described several alternatives to control
the flooding in this basin. As in this study, the City of Daytona Beach study evaluated the detention
of the runoff from the Airport Planning Area. The recommendations of the Daytona Beach study
suggested that the airport improvements could be combined with other improvements to decrease the
flood stages in this basin. The City of Daytona Beach study also suggested that the construction of
an additional outfd with a regional detention facility would help relieve flooding problems in the Reed
Canal Planning area. The estimated 1995 cost for this improvement as presented in the City of Daytona
Beach report (CDM., 1989) is $28.6 million dollars.
The Reed Canal Planning Area contains the most serious flooding problems in the Nova Canal system
watershed. A number of improvements have been suggested for this area as presented above. The
estimated cost to implement all these improvements is $5.3 million. Table 4-18 is a summary of the
improvements along with the associated cost. Each individual improvement will lower the predicted
0 peak 100-year flood elevation in the system, but all improvements are needed to have a significant
reduction in current flooding problems.
4.3.6 Halifax Canal Planning Area
According to the model, the Halifax Canal planning area has several areas that are predicted to have
water quantity problems. In these areas the canal overtops its banks and inundates the adjacent property.
One of the primary factors causing LOS violations is the undersized culvert under. Commonwealth
Boulevard. The existing culvert is a 48" x 72" elliptical corrugated metal pipe.
The consulting engineer for the City of Port Orange has recommended that this culvert be replaced
with a two 6' x 10' box culverts. The other structures that are located between Dunlawton Boulevard
and Commonwealth Boulevard and also recommend to be replaced with structures that have a cross
sectional area of at least 80 square feet. It is also recommended that the structures upstream ofDunlawton
Boulevard be re-evaluated when more information became available (QLH, 1990). With all of the-
recommended improvements in place, the City of Port Orange study predicted a peak stage elevation
of 6.53 feet NGVD.
The rainfall associated with Tropical Storm Gordon produced flood stages in the Halifax Canal that
were above the 100-year flood elevation predicted by the model. The storm flooded several homes
and closed some of the roadways in the basin. In particular, homes along Spruce Creek Road and
in the vicinity of Dunlawton Boulevard and Powers Avenue were flooded. Spruce Creek Road, an
arterial roadway, was closed. A hurricane evacuation route, Dunlawton Boulevard, was also closed
because of flooding. The 36-inch culvert located close to the intersection of Spruce Creek Road and
Jackson Street was washed out during the storm. This 36-inch pipe was replaced with a 48-inch pipe
which is still smaller than the up and down stream culvert sizes.
The first alternative that was modeled was the replacement of the culvert under Commonwealth Blvd
with two 6' x 10' box culverts. The intermediate culverts located between Dunlawton Boulevard and
Commonwealth Boulevard were modeled at their existing sue. The model in this configuration predicted
peak flood elevations of 5.6 feet NGVD and 6.2 feet NGVD during the 100-year event at the
Commonwealth Boulevard and Dunlawton Boulevard canal crossings, respectively. Based on these
results it appears that only the Commonwealth Boulevard structure needs to be modified to reduce
the flood elevations in the canal. The estimated cost to replace the Commonwealth Boulevard structure
is $220,000. The itemized listing of the estimated costs for this improvement are included in Table 4-19.
Many of the other canal crossings are driveways and the canal will still carry the design flow even when
they are overtopped. In fact, it is important that no additional restrictive culverts be placed and the
existing driveways should remain as is to allow this overtopping to occur during design storm events.
Otherwise, additional downstream flooding will occur.
Even with the Commonwealth Boulevard improvements in place, Dunlawton Boulevard is not protected
&om flooding during the 100-year event which is a violation of the LOS criteria for an evacuation route.
The level of predicted flooding under existing conditions is shown in Table 4-20. Examination of the
topographic survey indicates that flood waters can overtop Dunlawton Boulevard at Ruth Street at'.
an elevation of 6.10 feet NGVD. Alternatives that were investigated to lower the 100-year flood stages
enough to protect Dunlawton Boulevard included the widening of most canals and the expansion of
most culverts. Theseimprovements helped but did not reduce the water level enough to protect Dunlawton
Boulevard at Ruth Avenue. Therefore, the only way to protect the road from flooding during the
100-year event is to raise the road to a centerline elevation of at least 7.0 feet NGVD. This would
entail filling the roadway by adding a maximum of 12 inches of pavement to the road at the lowest
point, replacing the curbing and regrading the right-of-way. The estimated cost is $410,000, as presented
in Table 4-2 1.
Another location of flooding in the Halifax Canal Planning Area is in the vicinity of Canalview Boulevard,
south of Dunlawton Boulevard. Flooding at this road is in violation of the 10-year LOS, and the level
of flooding is shown in Table 4-20.
@ 4.3.7 Eastside Planning Area
The sub-basins in the Eastside Planning Area only flow to the Nova Canal System during major storms.
For most storms, these areas discharge directly to the Halifax River, and, technically are actually a
part of the Halifax River watershed. Since they can flow to Nova Canal system on major storms, and
extreme event analysis is part of this evaluation, it was proper to include them in the SWMM model
and in this evaluation.
Only two areas in the Eastside Planning Area violate the LOS criteria, and these are listed in Table 4-22.
Both of these are at the upstream end ofthe system, and are close to Nova Road. Improvements discussed
above for other planning areas can help to reduce flooding in these two areas.
Some of the areas of the Eastside Planning Area have type "A" soils. For water quality improvements,
exfiltration systems in the well-drained soils of this planning area will be recommended to decrease
the direct discharge of the "first-flush" of stormwater runoff to the Halifax River. However, these-
exfiltration systems may not have any measurable effect on the water quantity problems in the Eastside
Planning Area.
4.4 WATER QUALITY PROBLEM AREAS
The pollutant load evaluation presented in Chapter 3 determined that there are large quantities of pollutants
being discharged into the Halifax River and Rose Bay from the Nova Canal system watershed. For
comparison purposes, Table 4-23 presents the acreage, total annual load (lbs), and area-based loading
rate (lblac) for the Indian River Lagoon/Mosquito Lagoon, Turnbull Creek, Halifax River, and Tomoka
River (draft form) watersheds as well as the Nova Canal system watershed for existing land use suspended
solids loads. As can be seen, the Nova Canal system watershed is about the same size as the Indian
RiverMosquito Lagoon and Turnbull Creek watersheds and smaller than the other two. However,
on an area basis, the suspended solids loading rate is about two times the loading rates for the other
coastal watersheds.
0 Based on the results of the PLSM modeling effort, it can be said that the Nova Canal watershed is
relatively homogeneous fiom a pollutant loading point of view, and almost all of the sub-basins have
a relatively high loading rate. The largest mass of pollutants is discharged by the Reed Canal outfall,
followed by 1 lth Street Canal outfall, and the Halifax Canal outfall. If there are any "hot spots", they
are the outfdls fiom the Eastside Planning Areas, which technically are direct discharges into the Halifax
.&ver and should be considered to be part ofthe Halifax River watershed. Table 4-24 presents a comparison
of area-based pollutant loading rates for several land use conditions in other watersheds of Volusia
County. As can be seen, the loading rate for the representative basin of the Nova Canal system watershed
is the highest of all presented.
All drainage basins are expected to experience an increase in pollutant loads for the hture land use
condition. This increase will only be slight because the Nova Canal system- watershed is already highly
developed. This increase will occur despite the fact that future development will be required to install
stormwater treatment systems because the current state of stormwater treatment technology does not
attain 100% removal efficiencies. This is congruous with the findings of CDM (1994) in Daytona Beach-
and Holly Hill areas of the Halifax River watershed - that fhture loads were essentially the same as
the present land use loads. On an area-wide basis, none of the drainage basins have an intensity of
pollutant loading sipficantly higher than any of the others, though the overall loading rates are high
and indicative of urban areas. The fact that most of the urbanization has taken place on soils that, under
natural conditions, were " D soils, increases the pollutant loading rate and the total annual pollutant load
compared to an area with soils that can achieve greater infiltration of runoff. From a pollution abatement
point of view, " D soils and a high groundwater table make for conditions that are difficult for designing
cost-effective retro-fit improvements. Dry retention areas, swales, and exfiltration systems, that work
well in "A" soils can not be used for stormwater treatment in most of the Nova Canal system watershed.
To evaluate the relative magnitude of non-point source loading, a comparison of point and non-point
source loads was made. Table 4-25 presents the following:
1. Municipal wastewater treatment plant loads discharging into the Halifax River (point sources),
2. Non-point source loads from the Halifax River watershed for the existing land use,
3. Non-point source loads from the Nova Canal system watershed for the existing land use, and
4. Estimated pre-development non-point source loads to the natural receiving water.
The point source and Halifax River watershed non-point source loads were taken from the Halifax
River Watershed Management Plan by Camp, Dresser and McKee (1994). The existing land use loads
to the Halifax River and Rose Bay from the Nova Canal system watershed are from this report. The
estimated natural or pre-development non-point source loads were computed using the loading rate
for the Turnbull Hammock watershed (Marshall, McCully & Associates, 1994) presented in Table 4-24.
The areas contributing to the Halifax River, Tomoka River, and Rose Bay receiving waters under natural
conditions were estimated by the following:
1. The 1 1 th Street Canal Planning Area and the Bay Street and Madison AvenueICypress Street Outfall were assumed to naturally contribute to downstream Tomoka River,
2. The Airport Planning Area was assumed to naturally contribute to upstream TomokaRiver,
3. The Halifax River watershed, as presented by CDM (1994) was assumed to naturally contribute to the Halifax River, and
4. The Reed Canal, MagnoliaILive Oak Street, Wilder Boulevard, Bellevue Avenue, and Halifax Canal Planning Areas were assumed to naturally contribute to Rose Bay.
Because of the Nova Canal system, the W a x River is currently receiving direct flows and stormwater
loads that were transmitted to the Tomoka River and Rose Bay under natural conditions. The Nova
Canal system short-circuits the natural hydraulic pattern of freshwater flow into the Halifax River.
Comparing loads between point and non-point source discharges, point source loads (wastewater treatment
plant discharges) are smaller for every constituent except total phosphorous. The current point source
load of phosphorous is about equal to the total non-point source load to the Halifax River. In general,
the following observations can be made regarding non-point source loads compared to point source
loads for the other constituents:
1. Non-point source total nitrogen (TN) loads are about two times the value for point sources,
2. Non-point source solids loads are about 35 times the point source loads,
3 . Non-point source loads for oxygen demanding wastes (BOD and COD) are almost seven times the point source loads, and
4. Non-point source loads for metals (Pb, Zn, Cu, and Cd) are over 30 times the point source loads.
Thus, it appears that non-point source loads have a much greater pollution potential than point source
loads. Removing the discharges fiom wastewater treatment plants into the Halifax River are an important
part of a plan to improve water quality in the Halifax River. However, without providing treatment
for non-point source loads, particularly those being contributed by the Nova Canal system watershed,
the Halifax River will still continue to receive the bulk of pollutant loads fiom non-point sources.
When the estimated natural or pre-development loads to the W a x River were compared to the existing
point and non-point source loads (Table 4-25), the following observations can be made:
1. The estimated pre-development total nitrogen (TN) load was about thirty percent of the current non-point source load, and about twenty-five percent of the current total point plus nonpoint source loads,
2. The estimated pre-development total phosphorous (TP) load was about ten percent of the existing non-point source load and about four percent of the current combined point and non-point source loads,
3. The estimated pre-development total suspended solids load was about ten percent of the existing non-point source load and about nine percent (about the same) for the current combined point and non-point source loads,
4. The estimated pre-development BOD load was about seven percent of the existing non- point source load and about sii percent (about the same) for the current combined point and non-point source loads, and
5. The estimated pre-development metal loads (Pb and Zn) were about eleven percent of the existing nonpoint source loads and about the same for the current combined loads.
j, : :. 0 This rudimentary loading analysis indicates that point plus non-point source loads should be reduced
by about 90% to achieve material loads that are close to the pre-development conditions. Since the
largest relative loads are non-point source loads, most of the reduction needs to be in non-point source
loads. In any urbanized basin this is a dacult job, but it is made even more difficult by the large areas
of " D soils that are present in the Nova Canal system watershed. Because almost all sub-basins had
high loading rates, any developed area without stormwater treatment facilities in this watershed can
be targeted for improvements.
The remaining undisturbed andlor undeveloped parcels between Nova Road and U. S. Highway No. 1
should be considered for acquisition or for a very limited level, if any, of development. These areas
are not only important because of the need for additional flood plain storage, but many of these areas
may be able to be used for stormwater treatment. Considering that the retro-fit of existing development
in the Nova Canal system watershed will take an extended period of time, the preservation of these
parcels for potential use in the hture for water quality improvement is one of several good reasons
to consider an acquisition program as part of both water quantity and water quality improvements. 0 As was discussed earlier in this chapter, swales, dry retention areas, and exiiltration trench systems
only work where the soils are well drained and the water table during the wet season is well below
existing grade. These conditions only exist on the extreme east and west sides of the watershed. On the
east, adjacent to U.S. Highway No. 1, the ridge has primarily commercial development upon it, with
a high percentage of impervious area. Swales and retention areas would not be as suitable in this area
as exfiltration systems, due to the lack of available land. Edtra t ion systems can be installed beneath
existing pavement, although additional open space in these areas would be functional for stormwater
management as well as adding some aesthetic improvement to some of the areas that are extensively
paved. The loss of paved parking, if taken for stormwater management, would probably be opposed
by many merchants. Additionally, in this area, the topography is such that the grade falls away from
U.S. Highway No. 1, meaning that any exfiltration system installation would need to be placed on the
back (west side) of the lot, and the exflltration system would not be able to be placed in the public
right-of-way. However, to obtain a ball-park cost for exfiltration for this easterly area, it was assumed
Q that the existing grade elevation and water table conditions were suitable f?om about 5th Street in Holly
Hill south to Live Oak Street in Daytona Beach, a distance of about 12,150 feet. At $50/linear foot,
a cost of about $600,000 is estimated for exfiltration systems. These exfiltration systems would not
be continuous or linear, and would need to be designed with site specific information.
A slight rise in the center of the watershed, in the vicinity of Oleander Street and Virginia Drive may
also be suitable for an exfiltration system. However, the length of suitable soils along these roads is
only 1,300 feet. The cost for this section of exfiltration system is estimated at about $65,000. Installing
exfiltration in this area reduces both stormwater runoff flows and pollutants that would otherwise run
into the Nova Canal system.
In the west side of the watershed, any developed area above elevation 15.0 feet NGVD that is not
equipped with stormwater management facilities should be considered as a candidate for exfiltration
systems or swales. Retro-fit of older development with exfiltration systems or swales will reduce both
existing runoff and pollutants before they run off of the ridge into the Nova Canal system. This practice Q of "source reduction" allows the facilities that will have to be installed in the areas of poor soils to
be smaller in size and therefore less expensive because the volume of flow and mass of pollutants has
been reduced. One problem with swales or exfiltration systems in the western part of the watershed
is that there are a number of mobile home parks in which the streets are private, and access easements
would need to be obtained for construction of facilities and for operation and maintenance.
To obtain a ball park cost estimate,,it was assumed that there are approximately 240,000 linear feet
ofexisting roadway (46 miles) in this western ridge area that could be retro-fittedwith swales or edtration
pipe systems. This estimate was based on the subdivisions that were existing on the 1981 and 1983
Abrams aerial topography above the elevation 15.0 feet NGVD contour. Ln about 20% of the area,
the density of development is so high that swales cannot be used, and only exflltration systems are
assumed to be applicable. In other areas, constraints such as steep grades also mean that wales cannot
be used. If it is assumed that 35% of the area can be served by exfiltration systems at a cost of $50/foot,
an estimated cost for exfiltration systems in this western ridge area is about $4.2 million.
Usiig swales for the remaining 65% ofthis western ridge area, at a cost of $1 5tfoot for swale construction, i ." ., i .
wiUcost approximately $2.34 d i o n . The combined estimated cost for exfiltration and swaleirnprovements
in the western ridge area is therefore about $6.5 million. This must only be considered to be a ball-park
estimate, as site specific items such as pavement replacement, utility conflicts, etc. obviously were
not considered.
After source reduction has been accomplished in those areas ofthe watershed where swales and eatration
systems can be installed, the remaining area can be considered for pollution abatement and water quantity
improvements. This area between Nova Road and U.S. Highway No. l/FEC Railroad is an area of
poorly-drained soils and very little topographic relief. It is also an area that is intensely developed,
with little uncommitted open area. Even in the remaining undeveloped areas, the water table is high
and wet detention ponds become land intensive.
Wet detention facilities do not require well-drained soils or deep wet season water tables. However,
in a highly urbanized basin such as the Nova Canal Watershed, the construction ofwet detention facilities
63 could require the purchase of multiple existing homes, which is usually expensive. Therefore, alternative
techniques were evaluated to accomplish pollutant load reduction.
Alternatives considered for this area for water quality improvements include management practices
that are operation and maintenance intensive. These processes have come to be known as treatment
trains. They generally consist ofunit processes in series, each ofwhich treats a certain type of constituent.
For example, a sophisticated treatment train may include a baffle box to remove larger particles, an
oiYwater separator for oils and greases, and alum injection followed by a settling pond area for finer
sediments and nutrient control. Unfortunately, only the bafne box concept has been adequately tested
for use, with progress being made towards proving the applicability of the other unit processes.
In the area between Nova Road and U.S. Highway No. l/FEC W o a d within the watershed limits,
there are approximately 5,500 acres. For the purposes of evaluation, the weighted impervious percentage
average for these areas was assumed to be 50%, meaning the impervious area is about 2,750 acres.
0 Using an area of 5 acres for each baffle box, about 550 baffle boxes would be needed. At a cost of
$20,000 per large b d e box, a total cost for baffle boxes of about $1 1 million is estimated for baffle
box construction.
Baffle boxes must be cleaned almost every week during the wet season (6 months). The estimated
annual maintenance cost for the 550 baflle boxes is $330,000. Baffle boxes are not the most efficient
devices but their use can help to make other downstream improvements more effective. An example
of a baffle box is shown in Figure 4-6.
The use of existing features such as existing lakes and undeveloped low areas was also investigated
for water quality improvements. Along the Railroad Canal North and South there are several areas
that are lower than the surrounding area and have potential for use as a natural treatment facility and
for flood water storage. Without clearing the natural vegetation, the water transported by the ditch
can be forced out of the banks onto these parcels, where some removal of suspended solids and nutrients
would occur. However, ifwetland species are present, pre-treatment in a wet detention pond before-
discharge onto the parcels may be required. The cost for construction ofthis diversion facility is presented
as Tables 4-26 and 4-27 and is estimated at about $290,000 for the areas north of 1 1 th Street and $994,000
for areas south of 1 lth Street. A schematic diagram of these improvements are shown in Figure 4-7.
On Reed Canal, the City of South Daytona has considered the acquisition and utilization of a parcel
of land east of the FEC Railroad, behind the Rinker Materials Company industrial site, for a settling
basin and sediment management site. Though the site is too small to achieve high efficiency of suspended
solids removal, a wet detention pond on part of this site as well as an area for handling sediment material
removed fiom Reed Canal would benefit water quality. The cost of purchasiig this parcel, constructing
a wet detention pond and an area for sediment storage and handling is presented in Table 4-28, and
is estimated at $2,100,000. A schematic diagram of these improvements are shown in Figure 4-8.
Just to the south of the intersection of Reed Canal Road and Nova Road is a former County borrow
pit that is now used as a park (Reed Canal Park). The mobile home parks and subdivisions to the west
I.;.,: Q3 direct their drainage via several ditches to the Nova Road Canal South reach. While parts of these
subdivisions are in areas with sufficient elevation for exfiltration systems or swales, there is also si@cant
area on the downslope that cannot utilize these practices. As one alternative, an interceptor storm
sewer can be constructed to convey stormwater fiom these facilities into the County park lake for treatment.
At the present time, the lake is not connected to Nova Road Canal, and some utilization of the lake
for fishing has been observed. However, this lake is not a natural lake, and even through water quality
within it is probably very good and may deteriorate with the introduction of stormwater runoff, there
are few options in this area for treatment facilities. The cost of a storm sewer to collect runoff fiom
the surrounding area is estimated at about $125,000, as shown in Table 4-29.
In the same vicinity north of Reed Canal Road there are several relatively large lakes that appear to
have been dug for the fill that was placed adjacent to it, on which developments were constructed.
The ditch along Big Tree Road near the Nova Road intersection could be diverted into the lake nearest
Big Tree Road, then through two other lakes before discharge into the Nova Road Canal. A control
..(I
structure would be needed during times ofhigh water, such as Tropical Storm Gordon, as the developments- - 3,. : ' 0 surrounding the lakes have roadway elevations below the stages reached in Nova Road Canal during
this storm, but the development was somewhat protected by the berm along the east side of the canal,
the storage that was available in the lake, and the finished floor elevation of the existing residential
units. The cost ofthis flow diversion was estimated at about $120,000, as shown by Table 4-30. Figure 4-5
shows a schematic of this improvement.
At the outfall of the Wider Boulevard storm sewer system, one of the Eastside basins, there is an area
of open water and salt marsh vegetation on an island upon which has been placed a radio antenna.
There is a dirt road leading to the antenna, which forces the tidal flow through a small culvert under
the dirt road. The Wider Boulevard outfd may be able to be diverted into this area for wet detention.
While the regulatory agencies have not embraced this concept of in-river detention, there is another
part of the island that is composed of spoil material fiom dredging operations. This dredge spoil could
be used to help build a containment berm on the east side of the open water, with the disturbed spoil
area brought back to natural grade with the habitat restored as mitigation for the utilization of the open
water area for treatment and construction of the berms. With the addition of mitigation activities, the
regulatory agencies may be willing to re-consider the concept oflimited use ofin-river detention, particularly
at this location. The estimated cost for this facility, presented in Table 4-3 1, is $530,000.
For the area between Nova Road and U.S. Highway No. 1 within the watershed, none of the treatment
alternatives presented above reduce the volume of fiesh water being conveyed to the Halifax River.
The goal of a swimmable/fishable Halifax River means that this problem must be addressed, which
is directly related to the water quantity (flood) problems. Suggesting a reduction of flow given the
flooding problems of Tropical Storm Gordon may be considered to be a waste of time and effort.
However, theNova Canal system at the present time is not managed, and, as has been presented previously,
has not maintained. During many dry years, if flow control devices were in place at the outfalls, flows
could be significantly reduced, particularly after source reduction improvements have been accomplished.
In years such as 1994, with a higher-than-normal rainfall volume, flood reliefwould be needed. However,
without a comprehensive system management program in place, and committed governmental agencies
that are capable of looking beyond jurisdictional limits, improvement of the water quality in the ~a l i fax-
River does not appear to be an achievable goal.
4.5 ADDITIONAL OUTFALLS
Without in-depth consideration, it is thought that increasing the discharge of water from the Nova
Canal system to the Halifax River will alleviate flooding problems in the watershed if the flow can be
large enough and the conveyance capacity throughout the system is adequate to cany that flow. Increasing
the discharge means the construction of additional outfalls andlor increasing the size of the existing
outfds. Most of the capital improvements that are discussed above utilize storage to accomplish the
same fbnction as increasing the discharge rate. The provision of additional storage has a benefit that
is primarily confined to the specific reach near the improvement within the Nova Canal system. The
outfd discharge rate and the outfall conditions are so important hydraulically that increased outfall
discharge rate has a wider ranging effect, but not as wide ranged as might be thought. Additional analysis
was performed using SWMM to evaluate the affect of an increased discharge.
Before beginning an analysis of the effect of additional outfalls, the reaches of the Nova Canal system
that will not benefit fiom additional outfall capacity can be eliminated fiom consideration. The Halifax
Canal, which begins at Herbert Street and ends at the discharge point in Rose Bay, flows south, away
fiom the other reaches of the Nova Canal system. Additional outfalls to the Halifax River will have
little effect on the hydraulics of the Halifax Canal. Therefore, the Halifax Canal which discharges into
the Rose Bay OFW was not considered in the analysis. Sdar ly , because the systems in the Eastside
Planning Area only overtlow into the Nova Canal system on an intermittent basis and primarily discharge
into the Halifax River, they were also eliminated from the analysis.
Several alternatives for new discharge locations were evaluated based on the water quantity and water
quality problems in the 1 1 th Street, w o r t and Reed Canal Planning Areas. In running the SWMM
model, it was found that as the capacity of the outfall is increased, a point is reached at which little
reduction is seen in the elevation of the water surface for the main reaches, despite increases in the
size of the outfd. Therefore, for this analysis, the size of the outfall was considered to be maximized
when the water surface profiles showed that there was no reduction in water elevation with increased' ,$ -1 I:,.. 0 outfall size at a reference location for a particular storm.
In order to evaluate the effect of new discharges, the 25-year storm event was used for flow rate
comparisons as this criteria is typically used by the regulatory agencies in the evaluation of stormwater
management system hydraulics. However, when evaluating flood elevations or reductions of water
surface elevations, the 100-year event was used as this is the typical criteria for flood evaluations.
Using both events for the comparisons allowed for a comprehensive evaluation to be performed.
To evaluate the effect of additional outfds on the elevation ofthe water surface in the canal, two additional
outfds were added to the SWMM model. The most effective increase in capacity was achieved with
two additional outfds between the 1 lth Street Canal and Reed Canal, and an additional outfd at or
near Reed Canal Road (or an increase in Reed Canal discharge capacity). The outfall locations were
chosen based on the need for water level reduction in the canal and right-of-way availability between
Nova Canal and the Halifax River. The additional outfalls that were modeled were placed between
6th Street and Mason Avenue in Holly Hill (North Outfall) and between Bellevue and Wider Boulevard
in Daytona Beach (South Outfall). These improvements are shown on Figures 4-9 and 4-10, and are
referred to as Alternative 1. Ln order to achieve a 1.0 to 1.5 feet reduction in flood stages during the
100-year event over most of the Nova Canal system between 1 1 th Street and Herbert Street, double
10' x 10' box culverts and a single 10' x 10' box culvert were modeled to connect the main reach of
the Nova Canal system along Nova Road to the North Outfall and to the South Outfall, respectively.
To increase the discharge at Reed Canal, an additional 10' x 10' box culvert parallel to the existing
canal was simulated along Reed Canal Road. Other increases in existing culvert sizes along the main
reach of the Nova Canal are also required to achieve the maximum discharge, including the box culvert
between Orange Avenue and Third Street and the driveway culvert crossings between Reed Canal
Road and Herbert Street.
According to the SWMM model, the maximum effective discharge that can be obtained fiom the Nova
Canal system is 2200 cfs for the 25-year, 24-hour storm. When discharge at the outfall structures was
increased even further in sue for each of the four outfall locations, little reduction in flood stages was
0 seen. When the system is operating at maximum flow, a 1.0-1.5 feet reduction in water level in the
canal is predicted compared to the existing canal configuration in a clean condition.
To evaluate the effect of other improvements on the behavior of the maximum discharge configuration,
several other scenarios were examined. The maximum water level reduction was achieved with the
addition of storage by including the Big Tree Viage Retention Area and the Airport Detention Area.
With these improvements, the flood stages were reduced slightly between International Speedway
Boulevard (U. S. 92) and Reed Canal Road. Backflow preventors were also modeled with the maximum
discharge configuration. This caused the water level to increase slightly south of Reed Canal Road
because the backflow preventors reduce the available storage in South Daytona.
For the 25-year storm event the peak discharge of 2200 cfs is more than double the existing condition.
However, based on discussions with the regulatory agencies, this improvement would not be allowed
because the adverse impact on the quality of the W a x River would be expected to be severe. Allowing
0 these impacts to occur is also contrary to the mission of the Halifhxhdian River Task Force, to achieve
a swimmableJfishable Halifax River. Therefore, increasing the discharge to the maximum allowable
is not recommended for inclusion in a capital improvements plan for this watershed.
The second alternative modeled (Alternative 2) was the construction of additional outfalls as described
above, but with no total increase from all four outfalls above the existing condition peak discharge
or volume for the 25-year storm event. For the existing outfalls at 1 lth Street and Reed Canal, this
requires a reduction in the existing discharge. This can be accomplished by providing storage and
constructing a control structure. For Alternative 2, for the two new outfalls, on-line retention or detention
areas with control structures were also modeled. The box culverts would connect the main reach
of the Nova Canal system to a detention pond, which would then overflow through a control structure
into a smaller box culvert discharging to the Halifax River.
The North Outfall was modeled with a double 10' x 10' box culvert leading to staged detention ponds,
with a total surface area of about 25 acres. These ponds overflow through a control structure into- 0 ': a 6' x 8' box culvert discharging to a final detention pond directly adjacent to the Halifax River, then
into the River. Figure 4-9 shows the layout of the North Outfall Alternative 2 improvements. The
South Outfall was modeled with a 10' x 10' box culvert leading to a detention facility northeast of the
intersection of Bellevue Avenue and Nova Road. This detention facility is approximately 25 acres
in size, and has an outfall structure overflowing into a 5' x 8' box culvert discharging to the Halifax
River. Figure 4-9 shows the layout ofthe proposed South Outfall improvements. Along the existing
1 1 th Street Canal, detention areas for the Railroad Canals (North and South) as proposed in Section 4.4
are included for peak flow attenuation and treatment. Combining these with a control structure for
the 1 lth Street Canal outfall reduces the peak discharge fiom this canal by approximately 40% during
the 25-year event.
Similar irnprovements can be implemented on Reed Canal to reduce the discharge. The Reed Canal
regional treatment facility proposed in Section 4.4 wdl increase the storage in the system, and a control
structure at the Reed Canal discharge will be needed to reduce the discharge. These improvements
reduce the peak discharge coming fiom Reed Canal by about 40% during the 25-year event. The Big
Tree Retention Area and the Auport Detention Area along with larger culverts in some locations are
included in this alternative. For the Nova Canal North reach, the SWMM model of Alternative 2 predicts
a 0.5 to 1.0 feet decrease in 100-year, 24-hour stormwater levels for most of the reach. For the Nova
Canal Central reach, there is approximately a 1.0 feet decrease in the 100-year flood stage.
For the Nova Canal South, a slightly less than 0.5 foot improvement is predicted in the water level
for the 100-year event. The itemized costs for improvements for Alternative 2 are shown in Tables
4-32 through 4-36.
Fi y r e s showing the flood profiles for the main reaches of Nova Canal for Alternatives 1 and 2 are
presented in Appendix B along with the existing condition 100-year flood profile. Figures 4i and 5i
show flood profiles for the Nova Canal North, Figures 8i and 9i show the Nova Canal Central, and
Figure 12i shows the Nova Canal South.
The cost for both of these alternatives was estimated and is presented by Tables 4-37 and 4-38. L' !<:. . : 0 Alternative 1 was estimated to cost about $44 million and Alternative 2 was estimated to cost about
$37.6 million. For comparison, all of the recommended improvements presented in the previous sections
of this report are estimated to cost a total of slightly more than $3 1 million.
Neither of these alternatives using two additional outfalls yield a large enough reduction in flood stages
to eliminate all of the flooding problems associated with the Nova Canal system. From modeling results
it appears that it probably is not possible to achieve a two to three foot reduction in flood stages during
the 100-year event with only two additional outfds, which would protect all areas of the watershed
fiom flooding. This is due to capacity and hydraulic gradient limitations of the canal itself, limiting
the volume of water discharged through a s i d e outfall. Because the estimated cost of two additional
outfalls is greater than $3 0 million, any more than two additional outfalls cannot be shown to be a substantial
enough benefit to justifi the large expenditure.
8 The use of additional outfalls was previously evaluated in the City of Daytona Beach Stormwater Master
Plan (CDM, 1989). The proposed improvements in this 1989 plan achieved a reduction in canal stages
of about one foot for most of the reach for the 25-year, 24-hour storm event. The major difference
between the alternatives presented above, and the improvements evaluated in the Daytona Beach study
was the location ofthe north outfall. The additional outfalls in the Daytona Beach study resulted in
an increase in the existing discharge, but treatment was proposed in a wet detention facility located
in the Cypress Street area. This detention area has since been used for treatment of runoff for Cypress
Street improvements.
4.6 FLOOD PLAIN PROTECTION AND RESTORATION
The Nova Canal system watershed is a highly developed basin. There are relatively few undeveloped
parcels remaining, some of which have been cleared of natural vegetation, and some of those have
also been filled. Some of these parcels have not developed because of their flood prone nature. However,
unless changes to current Comprehensive Land Use Plans andlor Land Use Regulation are made, these 'ZY' ' .' , , ., 0 areas are expected to eventually be developed and filled. Since most of these are within the limit of
the 100-year flood as predicted by the SWMM model, this will reduce existing flood plain storage
and exacerbate the existing flooding problems. One solution to avoid this problem is the implementation
of a flood plain protection and restoration program. Storage for flood waters can be protected by
purchasing undisturbed parcels within the flood plain and maintaining the existing available storage
on those sites. Flood plain restoration can be accomplished by purchasiig parcels that are not developed
but may be higher in elevation because of %g, which can then be excavated to provide flood storage,
and in some cases provide treatment resulting in a water quality benefit.
To assess the current situation, vacant parcels that currently provide or could potentially provide flood
plain storage were identified from 1994 aerial photographs. These parcels are numbered and shown
on Figures 4-1 1A and 4-1 1B. Table 4-39 presents the acreage and location of each of these parcels.
All of the identified parcels were scored individually according to criteria that evaluated the condition
of the site. The factors that determined the score for the vacant parcels for this analysis include:
1. Whether the site is presently cleared, undisturbed, or partially cleaned;
2. Whether the soils on the site are hydric, not hydric or, hydric on part of the site;
3 . Where the site is adjacent to, close to, or away fiom the canal;
4. Whether the site is currently under government ownership, not under government ownership, or partly under governmental ownership;
5 . Whether the elevation of the site is relatively low, moderately low or, not low; and
6 . Whether the site is within the flood plain, not within the flood plain, or partially in the flood plain.
Table 4-40 presents the result of the evaluation of the vacant parcels using these factors. Each parcel
is shown to be rated with a high, medium, or low priority for use for flood plain protection or restoration.
The thresholds for these relative values were chosen somewhat arbitrarily, according to groupings
that appeared after the scores were totaled. It should be noted that this is only, an initial prioritization,
and hrther analysis needs to be performed for each site to determine the viability for purchase.
This inventory only examined parcels that are not developed. Developed parcels which were originally
or are currently in the flood plain should also be considered for acquisition. Developed lots which
have been abandoned can be the most usehl, because they can sometimes be acquired at a relatively
low price. Once developed parcels have been obtained, any impervious area can be removed and the
site can be regraded to the most beneficial elevations for both flood plain restoration and use for recreational
facilities. Control structures can be installed to maximize the storage capability of the site.
Some of the vacant parcels may not be suitable for maximhhg storage, particularly those with wetlands
or other limiting factors. In other cases, negotiations with the land owner may allow the allowable
intensity of development of the land use to be Limited so that the parcel remains usel l for flood storage,
and yet does not need to be actually purchased. In some cases, the negotiated settlement may need
to include cash payment for loss of potential land use. However, when the parcel has value for active
recreation as well as for flood storage, the parcel should be acquired.
Q Some of the parcels may no longer be connected directly to the Nova Canal system because of a road
bed or a berm that separates the land area fiom the waters of the canal. In those cases the parcel will
need to be reconnected through the use of pipes and control structures. In particular, parcels that are
also used for other purposes besides flood storage (such as parks) will be most usefbl if the flow of
flood waters into the site is controlled in some manner.
The cost of purchasing all of the "high priority" parcels shown in Table 4-40 is estimated to be between
$10 and $13 million. The parcels have not been identified according to the municipality or unincorporated
area where they are located because this improvement should be seen as an improvement that provides
benefit throughout the watershed. In contrast, an improvement such as a pump station is typically very
limited in the area of benefit, usually only in the subdivision or several subdivisions of a single municipality
in which the pump station is located. Because of this, acquisition of existing vacant land to protect
the flood plain should have a high priority as a capital improvement because benefit can be received
for both water quantity and water quality by acquiring or controlling the land use of significant parcels.
TABLE 4-1
POLLUTANT REMOVAL EFFIClENClES FOR DRY RETENTION AREAS
SOURCE: Karkowski and Vickstrom, 1993
Constituent
BOD
Total Suspended Solids
Total Nitrogen
Total Phosphorous
Removal Efficiency
92%
85%
91%
61%
TABLE 4-3
POLLUTANT REMOVAL EFFICIENCIES FOR EXFILTRATION TRENCHES
SOURCE: Karkowski and Vickstrom, 1993
-- Constituent
BOD
Total Suspended Solids
Total Nitrogen
Total Phosphorous
Trace Metals
Removal Efficiency
60- 100%
60- 100%
40-80%
40-80%
90%
TABLE 4-4
WET DETENTION POND EFFICZENCLES FOR FIRST FLUSH TREATMENT
% of Removal Eff~cie of Removal EIXciency
SOURCE: Wanielista and Yousef, 1993
TABLE 4-5
TYPICAL OPERATION AND MAINTENANCE ACTMTIES FOR STORMWATER SYSTEMS
Mechanically and manually clean storm sewers
Construct, replace, repair small drainage structures
Mechanically and manually clean small drainage structures
Herbicide weeds that will impede the flow in ditch systems
Clean canal and off-system ditches with draghes
Clean limited access canals with special equipment
Clean roadside ditches with scoop
Clean roadside ditches with ditchmaster
Environmental gardening
TABLE 4-6
STORMWATER SYSTEM OPERATION AND MAINTENANCE
I Storm sewer cleaning and repair I Once each year I
ACTIVITIES AND LEVEL OF SERVICE
I Storm sewers serving major urban areas
. . . . . . . . . . Activity
I Two to three limes each year
Desired Level of Service . . . . .
I
Storm sewers prone to clogging
Canals and ditches prone to a build-up of material 1 Oncer each year
Two to three times each year
Street sweeping
Canal and dltch cleaning
TABLE 4-7 REPRESENTATIVE COSTS FOR STORMWATER SYSTEM
Once each week
Every five years
1 storm sewers I -- I $266,667/mile
iVIAINTENANCE AND REPLACEMENT
Item
Structures
Ditches
Canals
I I
Annual Maintenance Cost. Replacement Cost
SOURCE: Eighney, 1992
$95/structure
$10,365/mile
$2,52O/de
$1 2,50O/structure
$50,00O/rmle
$1 1 5,00O/mile
TABLE 4-8
I 90,000 I L.F. I
MAJOR CANAL MAINTENANCE ESTIMATED COST i ! Item [ Quantity
I I I I
L
Unit / Unit Cost I
Escavation & Disposal I I I I
Total Cost
Head wall Repair I I I I
I Esmated Total Cost I
125,000
Contingency
Engineering
($26.50 per linear foot of canal)
25 % I $35 1,875
C.Y.
100
15 %
EA. $450.00
$263,906
$10.00
$45,000
$1,250,000
TABLE 4-10
11 th STREET CANAL PLANNING AREA RIVERA OAKS SUBDlVISION IMPROVEMENT PLAN ESTIMATED COST
Engineering
Estimated Total Cost
15 % $120,938
$927,188
TABLE 4-1 1
I Museum Boulevard 1 7.5 1 8.38 ( 1 0 - y ~ Local Road I
AIRPORT PLANNING AREA LOS VIOLATIONS
*County Owned
. . .
LOS violation "Location
TABLE 4-12 AIRPORT PLANNING AREA
DETENTION POND ESTIMATED -- COST
TABLE 4-13 AIRPORT PLANNING AREA
MUSEUM ROAD DETENTION AREAS ESTIMATED COST
Engineering
Estimated Total Cost
* Land currently being used as mitigation for museum construction
Road , Elevation.:..
' ~ l o o d Elevation .:..
15 % $221,719
$2,699,844
TABLE 4-14
I Nova Rd. & Volusia Ave, I 9.8 I 10.27 1 100-vr Evacuation R o a r
REED CANAL PLANNING AREA LOS VIOLATIONS
Location
Nova Rd. & Orange Ave.
Orange Ave. East of Nova Rd.
Daytona Gardens Subdivision north of South St.
Road Elevation Flood Elevation (N GVD)
h d g e Crest Subdivision northwest of Beville Rd. & Nova Rd.
Mobile Home Park northeast of Beville Road & Nova Rd.
Golfiriew Subdivision at upstream end of Stevens Canal
(NGVD) LOS Violation
9.2
8.3
6.5
Big Tree Village
Mobile Home Park northeast of Reed Canal & Nova Kd.
8.2
7.5
6.2
Palm Grove Subdivision northeast of Reed Canal & Nova Rd.
9.48
9.77
9.87
6.7
7.5
100-yr Local Road
1 0-yr l x a l Road
I 0-yr Local Road
9.58
9.84
7.37
7.5
-
1 0-yr Local Road
1 0-IT I x a l Road
1 0-IT Local Road
7.83
9.5
I 0-yr Local Road
1 0-IT I.mal Road
8.94 1 0-yr Local Road
TABLE 4-15 REED CANAL PLANNING AREA BIG TREE VILLAGE
TABLE 4-16 REED CANAL PLANNING AREA
BIG TREE ROAD DETENTION FACILITY ESTlMATED COST
I clearing
Land Aquisition
I control ~ rmc~ures 1 5 1 Es. 1$5,000.00 I $25,000 I
Item
Aerial Sunleylng
I Dike Construction 1 1,800 1 L.F. I $100.00 1 $180,000 1
Unit Cost
$25.00
3 5
1 Contingency
Total Cost
$75,000
Quantity / Unit
I Engineering
3,000
Ac.
I Estimated Total Cost I
Ac .
$35,000.00 $1,225,000
TABLE 4-1 7 REED CANAL PLANNING AREA
STEVENS CANAL EXPANSION ESTIMATED COST
TABLE 4-18 REED CANAL IMPROVEMENTS SUMMARY TABLE
._ Cost
$2,185,000
$282,110
$733,125
Improvement
Big Tree Detention Area
Stevens Canal Espansion
Big Tree Village1 Martin Paving Pond
Description of Improvement
Detention area created using existing contours and berms
Widening of lower section of Stevens Canal where ROW is available
Pumping runoff fi-om the Big Tree V~llage Subdivision to a detention pond
TABLE 4-19 HALIFAX CANAL PLANNING AREA COMfilON W EALTH
BOULEVARD CULVERT IMPROVEMENTS EST]R,IATED COST - Item . . / Quantity 1 Unit 1 Unit Cost 1 Total Cost I
: . , ..' . . I
Escavation & Disposal I
Contingency I
Asphalt Base & Pavement
6' s 10' Bos Culvert
Headwalls
TABLE 4-20 HALIFAX CANAL PLANNING AREA LOS VIOLATIONS
(') - Marshall, McCully & Associates, 1994 (2) - Associated Technology and Management, 1994 (') - Camp, Dresser and McKee, 1994 (')- Mean valves for entire watershed, present land use conditions ('I - Described as "dissolved phosphorous"
DeLand Ridge0) Basin 1, DeLcon Springs Area
,LUTANT LOADING RAT
8.1
4.1
1.5
5 2
Nova Canal Reed Canal Planning Area
Mosquito Barrier Island Lagoon"'
Indian h v e r Turnbull Lagoon(') Ilammock
Tumbull Turnbull Creek"' Creek(4'
- - OP TSS
Mixed-Use Urban
Residential
Natural, Undeveloped
Kural Resid., Residential
Natural, Undeveloped, Some Resid.
ES FOR EXISTING CONDITIONS . -. -. . . . .-- . - - . ----. .- . .- . -- . . - . , . . . . . . . . . . - . .- . . . . . .- . . . . . .- . - . . . . - . -- .. T i f 1 B r 1 COD Pb 1 z n
489 304 0.54 0.39
4.4
TABLE 4-25 A COMPARISON OF EXISTlNG POlNT SOURCE LOADS, EXISTING NON-POLNT SOURCE LOADS,
Halifax River Watershed Nonpoint Source Loads 193,20 1
Nova Canal Watershed Existing Land Use A. Halifax River B. Rose Bay
Estimated Pre-Development Nonpoint Source Loads(2) A. Halifax River B. Tomoka River
Upstream Downstream
C. R o x Bay
TKN
76,565
LND --- EST
. TP
5 1,043
34,099
(I) Point sources are considered to be only wastewater treatment plant discharges. (2) Pre-development loads are assumed to be indicative of the natural (undeveloped) condition.
TABLE 4-26 1 lTH STREET PLANNING AREA
ILROAD CANAL NORTH RETENTION AREA ESTIMATED COST
Item S T = /
Aerial Surveying
Land Acquisi~ion
Clearing
1,000
5
Estimated Total Cost 1 $288,938.00 1
Ac .
Ac.
Control Structures
Contingency
Engineering
TABLE 4-27 11 th STREET PLANNING AREA
$25.00
$35,000.00
1
I Aerial Surveying
$25,000.00
$175,000.00
RAILROAD CANAL SOUTH RETENTION AREA ESTIMATED COST
1,000 1 Ac. I $25.00 I $25,000 I
Ea.
25%
15%
Total Cost 1
Contingency
$50,250.00
$37,688.00
$1,000.00
I .I
Unit Cost j Item
Land Aquisition
Clearing
Control Structures
Engineering
$1,000.00
. . . . . .
Quantity I Unit
I Estimated Total Cost
19
0
1
Ac.
Ac.
Ea.
$35,000.00
$1,500.00
$1,000.00
$665,000
$0
$1,000
TABLE 4-28
REED CANAL PLANNING AREA REED CANAL REGIONAL TREAT-WENT FACILITY
I Land Aquisition I 11 I Ac. 1 $40,000.00 1 $440,000
I Clearing I ' I
I Engineering
Excavation
Control Structures
- - - - - - -
I Estimated Total Cost I $2,136,125
TABLE 4-29
200,000
2
REED CANAL PLANNING AREA REED CANAL PARK LAKE WATER QUALITY TREATMENT
. . . . .
Item I Quantity I U n i t : [ Unit Cost ( 5
al . . . Cost. I
C.Y.
Ea.
Surveying 1 100 1 Ac. I EIOO.00 I $10,000 I
$5.00
$5,000.00
$1,000,000
$10,000
I I I I
36" Jack and Bore I I I I
Estimated Total Cost I 1 1122,188 1
Contingency I I
150
Engineering I 15%
25%
$15,938
L.F.
$2 1,250
$500.00 $75,000
TABLE 4-30
I Estimated Total Cost
REED CANAL PLANNING AREA BIG TREE ROAD DETENTION POND ROUTING
. . Total Cost
S 1.250
%SO,OOO
$20,000
$12,000
%20,8 13
$1 5,609
. .
Item
Surveying
36" RCP
Control Structures
Headwalls
Contingency
Enmneerine:
TABLE 4-31 EASTSIDE PLANNING AREA
WILDER BOULEVARD RIVER DETENTION AND MITIGATION
Item
Aenal Surveplng
Excavation
Berm Construction
Control Structures
Unit Cost "
$1.25
$50.00
$5,000.00
$4,000.00
Quantity '
1,000
1,000
4
3
Unit
Ac .
C.Y.
L.F.
Ea.
Quantity
500
20,000
2,000
1
25%
15%
. Unit . .'
L.F.
L.F.
Ea.
Ea.
$70,375
$5933 1
$456,406
Unit Cost
$25.00
$5.00
$100.00
$5,000.00
Contingency
Engineering
Total Cost
Total Cost
$12,500
$100,000
$200,000
$5,000
25%
15%
TABLE 4-32
NORTH OUTFALL BOX CULVERT lNSTALLATION ESTIMATED COST
Trench Eseavation with Dewatering I 60,000 I C.Y. I $10.00 1 $600,000 I 10 x 10 Bos Culvert I 4,000 I L.F. I $500.00 I $2,000,000 I 6 s 8 Box Culvert 1 7,000 1 L.F. 1 $400.00 1 $2,800,000 I Pavemcnt Cut and Repair 1 900 1 S.Y. 1 $25.00 1 $22,500 I Sodding
Contingency I I
TABLE 4-33
20,000
Engineering I I
Aerial Surveying
Estimated Total Cost
S.Y.
15 %
1 $8,242,266
25 %
$1,075,078
I I I I
$1,433,438
$2.50
Land Acquisition I I I I
$50,000
Clearing I I I I
I contingency
25
Excavation and Disposal I I I I
I Engineering
25
Control Structures
Ac.
325,000
Ac.
6
Estimated Total Cost
$50,000
C.Y.
$4,265,78 1
$1,250,000
$1,000 $25,000
$5
$30,000 Ea.
$1,625,000
$5,000
TABLE 4-34
I Trench Excavation with Dewatering
NOVA ROAD CANAL BOX CULVERT ADDITION ESTIMATED COST i ,; . . .
Item . . . . . " . . . . . . -
Surveying
I
I Estimated Total Cost I 1 $5,092,344 1
I I
TABLE 4-35
~ o t a l c o s t
$12,500
Sodding
Unit Cost
$1.25
Quantity I Unit:
12,000
$885,625 Contingency
..... 10,000
$30,000 S.Y.
25 %
SOUTH OUTFALL BOX CULVERT INSTALLATION ESTIMATED COST
L.F.
$2.50
I I 1 I
. . . Item . . , , .:
Sweymg
I I I I
Unit-Cost .
$1.25
$200,000 fight-of-way Purchase
I I I I
.
Quantity 8,000
Total Cost
$10,000
$600,000
I I I I
Unit .
L.F.
4
Trench Excavation with Dewatering
10 s 10 Box Culvert
I I I I
I Contingency
60,000 C.Y.
$500
$3,200,000 5 x 8 Box Culvert
Pavement Cut and Repair I 900 I S.Y. I $25 I I I I
1 Engineering
Ac.
$10
$500,000 1,000
$22,500
$50,000
L.F.
Sodding
$400 8,000
S.Y. 20,000
Estimated Total Cost
L.F.
$6,587,344
$2.50 $50,000
TABLE 4-36
SOUTH OUTFALL DETENTION AREAS ESTIMATED COST Item
I Aerial Surveying 1 1,500 1 Ac. 1 $25 1 $37,500 1 I I I I
I Excavation and Disposal 1 325,000 1 C.Y. I $5 I $1,625,000 I
Land Acquisition 1 I I I
I Control Structures 1 2 1 Ea. 1 $10.000 ( $20,000 1
ADDITIONAL OUTFALL ALTERNATIVE 2 ESTIMATED COST I 1 IklPROVEMENT COST
North Outfall Box Culvert
I Nova Road Canal MoMications I $5,100,000 I
$8,300,000
North Outfall Detention Areas I
$4,300,000 I
South Outfall Box Culvert
South Outfall Detention Areas
Additional Previously Recommended Improvements
$6,600,000
$4,300,000
$9,000,000
Total %37,600,000
TABLE 4-39
A LIST OF VACANT PARCELS IN THE NOVA CANAL SYSTEM WATERSHED THAT COULD HAVE
ALUE FOR PROTECTION AND RESTORATION OF THE FLOODPLAIN
63 IParque Dr; s. of Hand Ave & west of U.S. 1 Parque Dr; s. of Hand Ave & west of U.S. 1 State Ave; south Calle Grande Ave & west of U.S. 1 Laurel Oaks Circle; north of Fleming Ave & south of Hand Ave Arroya P h c . to Arron Circle & Calle Grande west of U.S. 1 Area between Golf Ave & Alabama Ave extended to Nova on west & Timber Trace on east. Area between Alabama Ave & Flomich St estended to Nova on west & Puzniston Ave on east. Between Tuscaloosa Ave & Mobile Ave extended from Flornich St. 1 Sherries Ln to Mammoth Cave west of U.S. 1 Evergreen Ave to Nova Rd west U.S. 1 Area between Kings Rd & Nova Rd estended from Manetee Circle to Walker St. From Walker St to middle of 8th & 10th st. west of U.S. 1 From Palm Terrace to 10th St west of Nova Rd Area between 1 lth St & 10th St next to Chlppewa Tr west of U.S. 1 Area from Flamingo Dr to 8th St behveen Lakewood Dr & Ronnie Circle . .
Area from 9th St to 6th St extended from Williarnsburg Dr to Holly St From 6th to 5th St behveen Nova Rd & Center Ln Area between Derbyshue Rd to Nova Rd & Brentwood Dr Madison Ave west of Nova Rd Behveen Madison Ave & North St west of Nova Rd Between Cavanah Dr & Center St east of Nova Rd Between 3rd & 2nd St eastt of Nova & west of Center Ln Between Mason Park Dr & Thomasson Ave extended from 2nd to Mason St. West of Clyde Moms Blvd between Dunn Ave and International Speedway Blvd. Behveen International Speedway Blvd. & Catalina Dr west of Clyde Moms Area east of Clyde Moms Blvd between Shyview Ln & Bcllcvue Ave Between Orange Ave & International Speedway west of Nova Rd Between Museum Blvd & Orange Ave west of Nova Rd Between Maley St and Kottle St east of Nova Rd Between Park Dr & Cedar St east of Nova Rd From Clyde Moms Blvd to Owasso St Extended from Museum Blvd & Bellevue Ave Between Owasso St & Bellevue Ave west of Nova Rd From Bellevue Ave to Glen Blvd between Terrace Ave & Nova Rd Between Clyde Morris & Midway Blvd west of Nova Rd
TABLE 4-39 (Continued)
A LIST OF VACANT PARCELS IN THE NOVA CANAL SYSTEM WATERSHED THAT COULD HAVE
VALUE FOR PROTECTION AND RESTORATION OF THE FLOODPLAIN
3 j 1 39 I Between South St & Bellevue Ave east of Nova Rd Between Nova Rd GatePark Dr south of Bellewe Ave Between Bcville Rd & June Ter west of Nova Rd From Nova Rd to Boulder Dr south to Big Tree Rd Behveen Boulder Dr & Big Tree Rd Behveen Old Kings Rd & Big Tree Rd west of Nova Rd Between Big Tree & Pearson Way to Nova Rd Area between Santana Dr & Amapola Ln & Nova Rd Behveen Piedmont Av & Nova Rd Betxeen Reed Canal & Old Sunbeam Dr East side of U.S. 1 north of Reed Canal South of Reed Canal behveen Davey Rd & Brook Circle From Reed Canal behveen Sauls St & Lantern Dr From Reed Canal between Gaslight Dr & Oak Lea Dr Between Clairmont Ln & McDonald Charles St west of U.S. 1 Between Piedmont Ave & Spring Dr west of Nova Rd Between Nova Rd & Jackson St extended fiom Walton Blvd to Four Seasons Blvd Between Hardwood Ave & Gordon St west of Nova Rd Behveen Old Hammock Rd & Gate Circle to Nova Rd Behveen Opportunity Ct & U.S. 1 Between Charles St & Herbert St west of U.S. 1 Between Herbert St & Powers Ave west of U.S. 1 Off of Dunlawton between Jackson St & Oak St Between Kokomo Circle & Dunlawton Between Dunlawton & New Haven Ct Between Dunlawton & New Haven Ct Behveen Spruce Creek Dr & Frederick Dr west of U.S. 1 Between Spruce Creek Dr & Frederick Dr west of U.S. 1 Behveen Tarrytown Dr & Nova Rd Behveen Lakeland Dr & Nova Rd Behveen Farmbrook Circle & Poncianna Dr east of Nova Between Kokomo Circle & Dunlawton
TABLE 4-40 +?!. ,&.:2:; Q RELATIVE PMORITY LIST FOR VACANT PARCELS
WITH THE POTENTIAL FOR VALUE AS PART OF A PROTECTION AND RESTORATION PROGRAM IN TEE NOVA CANAL SYSTEM WATERSHED -
1 2 1 2 2 1 1 9 I High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority High Priority
Medium Priority Medium Priority Medium Priority Mehum Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medlum Priority Medlum Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority Medium Priority
"q 6 TABLE 4-40 (Continued)
RELATIVE PRIORITY LIST FOR VACANT PARCELS WITH THE POTENTIAL FOR VALUE AS PART OF A PROTECTION AND
Cleared: I-Cleared or Disturbed 1.5-Partially Cleared 2-Forested Hydnc Soils: 1-All Hydric Soils 1.5-Some Hydric Soils 2-No Hydric Soils Canal Proximity: 1 -Adjacent to Canal 2-Close to Canal 3-Distant tiom Canal
Government Ownership: 1 Government Owned 1.5-Partially Government Owned 2-Not Government Owned
Elevation: 1 -Low Elevation 2-Medium Elevation 3-High Elevation Flood Plain: 1-Within the Flood Plain 2-Partially Within the Flood Plain 3-Not Within the Flood Plain
Non-structural improvements were discussed in a general manner in Section 4. Non-
structural improvements usually require a relatively small cost compared to capital
improvements. Specific non-structural improvements that are recommended to be
implemented in the Nova Canal system watershed are as follows:
1. The remaining existing undeveloped areas should be purchased to the extent possible by budgeting constraints, to preserve the existing flood plain storage. These parcels could be used for a variety of uses. Uncleared parcels could be managed as passive parks. Disturbed but undeveloped parcels could be evaluated for use as wet-detention facilities, or for ball-parks or other active parkland facilities that do not require any fill activities.
2. A flood plain reclamation program should be implemented to identi@ critical developed areas that could be acquired and returned to a field storage area with a hydraulic connection to the canal. An example of a parcel that fits the intent of this non-structural improvement is the large commercial lot at the southeast corner of the Reed Canal R o a m o v a Road intersection.
A minimum finish floor elevation one foot above the 100-year flood stage as predicted by the SWMM model should be established by incorporation in each municipal entity's Land Use Regulations. Rainfall from Tropical Storm Gordon produced flood stages greater than elevation 9.0 feet NGVD in many areas . Except in areas near the outfalls where a reduction may be warranted, elevation 9.0 feet NGVD is recommended as a reasonable estimate of the 100- year flood in the Nova Canal system watershed. The City of Daytona Beach currently uses flood stages predicted in the City of Daytona Beach Stormwater Master Plan (CDM 1989) for finished flood elevation standards. These flood elevations are similar to those predicted in this study, and are reasonable development criteria.
4. Future development should be required to provide flood plain compensation for any fill placed in the areas below the 100-year flood stage as predicted by the SWMM model. For simplicity purposes, utilizing elevation 9.0 feet NGVD as a reference elevation may be advisable. On many of the currently undeveloped parcels between Nova Road and U.S. Highway No. l/FEC Railroad, this restriction may preclude or limit development.
5 . An education program should be established throughout the watershed to help residents understand the limitations placed upon them because of their location in the coastal flood plain. The effects of adverse events, such as Tropical Storm Gordon, are easily forgotten until the conditions recur. An informational document should be sent to all stormwater utility customers monthly, or at least on an annual basis.
6. A co-operative effort should be implemented with respect to ownership, operation, and maintenance of the Nova Canal system. This is discussed in more detail in Chapter 7.
5.4 RECOMMENDED WATER QUANTITY AND QUALITY STRUCTURAL IMPROVEMENTS
5.4.1 General
Based upon the water quantity (Chapter 2) and water quality (Chapter 3) evaluations,
problem areas were identified and improvements to alleviate them were presented in
Chapter 4. In general, it can be said that from the information obtained during this study, it
appears that most flooding problems have been caused by development that was allowed in
areas of the coastal flood plain where development should have been restricted. There was
a reliance on the Nova Canal system to protect the residences and businesses and a
misunderstanding of the synergistic effects of extreme storm events, saturated soils, and high
tidal conditions. Pollutant loading problems have been caused by the intensity of development'
that occurred before stormwater treatment was required. Structural improvements were
developed that address both of these identified problems.
The purpose of this section is to discuss the recommended structural improvements for the
five planning areas. In all planning areas, source reduction is the most important structural
improvement, so that facilities needed for either water quantity or water quality purposes can
be minimized in size and cost. Recommended activities have been developed to address the
most severe problem areas. These recommendations are based on achieving a reasonable
levels of service (LOS) basin-wide as presented previously and the need for action in specific
cases due to severe or fiequent flooding problems or high pollutant loadings. Because of the
level of urbanization found in this basin, site-specific local problem areas and nuisance
flooding problems are not addressed within the scope of this study.
5.4.2 11th Street Canal Planning Area
The most significant flooding problem in the 1 lth Street Canal Planning Area occurs within
the Rivera Oaks subdivision. This particular subdivision has been investigated previously by
others, so alternative methods to alleviate flooding problems in this area were developed.
The least costly activity over the lifetime of the homes within this subdivision is to raise the
approximately 52 homes that are the most susceptible to flooding. The capital cost to
accomplish this is estimated at about $1 million, with no annual maintenance costs. However,
this alternative may not be possible to implement politically, so a more acceptable
recommendation is presented below.
An alternative for flood prevention within the Riviera Oaks Subdivision is to reroute runoff
away from this area. This includes physically separating the subdivision fiom the influence
of the Calle Grande Canal and routing the subdivision runoff to a detention facility on an i ' +,f:- 0 undeveloped area to the north. A dike would need to be constructed at the southern end of
-- the subdivision to ensure that stormwater flows corning from the ridge to the west go directly
into the Calle Grande Canal and not into the subdivision. Runoff from the subdivision can
then be routed to the north through two 48-inch culverts to a new 10-acre detention pond.
An outfall will be provided for this pond, connecting back to the Calle Grande Canal. This
outfall should be fitted with a back flow preventer to prevent high stages in the Calle Grande
Canal fiom filling the pond. This would still result in some road flooding on Rio Way, but
would not result in flooding of houses. The estimated cost of this improvement is $930,000
including land cost. The estimated annual maintenance cost for the culverts and the pond is
about $25,000 per year.
Source reduction and water quality improvements that have been identified for this planning
area include eatration systems and swales in the area west of Nova Road. For the Daytona
Beach Community College (DBCC) campus and other areas with a high percentage of DCIA,
exfiltration systems will allow the construction of the systems with no loss of parking. The
cost of an exfiltration system to replace the existing storm sewer that serves the DBCC
campus is about $550,000. Petroleum absorbents should be used in the inlets to capture oil
and grease. In the neighborhoods just to the east and north of DBCC and in the Derbyshire
Road area, field evaluations during the conceptual design phase should be undertaken to
determine areas where swales can be constructed. Where swales are not suitable, exfiltration
systems are recommended to be installed. The exfiltration systems and swales west of Nova
Road in the 1 lth Street Canal Planning Area are estimated to cost $1.2 million. On the east
side of the planning area, an exfiltration system for source reduction in the well drained soils
is estimated to cost about $2.2 million.
In the area between Nova Road and the U.S. Highway No. 1/FEC Railroad, alternative
technologies must be developed. Baffle-boxes have been identified as part of a unit process
treatment train. If adequate efficiencies cannot be obtained by treatment train processes, it
is recommended that existing developed land be purchased for the construction of wet
("-J -." detention facilities, or a combination of treatment train/wet detention be utilized to achieve
adequate treatment levels. A rudimentary cost estimate of $4 million has been assumed for
treatment train technology improvements.
Where possible, it is recommended that certain existing undeveloped parcels be used for the
diversion of flows fiom existing sub-reach ditches. One specific recommended improvement
is the diversion of flows from the Railroad Canal North and South into existing undeveloped
parcels adjacent to the ditch. The estimated cost of this land purchase and minor structures
is about $1.3 million. Before this improvement is implemented, a wetland determination
should be made on the subject parcels.
The recommended structural improvements for the 1 lth Street Canal Planning Area are
summarized in Table 5- 1.
5.4.3 Airport Planning Area
Navy Canal is the major drainage way serving the Purport Planning Area. The volume and
peak rate of runoff predicted to be transported from this basin to the Nova Canal system has
the potential to have a major impact on flood stages fbrther downstream within the other
planning areas. Therefore, reduction of the flow rate by attenuating the peak discharge is the
functional intent of the recommended structural improvements for this planning area. The
recommended improvements are a combination of a 300 ac-ft detention basin and a control
structure. The estimated cost of this improvement is about $2.7 million dollars. This
improvement will also provide water quality improvements by removing suspended solids.
Another recommended improvement for the Airport Planning Area is the diversion of the
downstream portion of Navy Canal to the low lying areas west of Nova Road and north and
south of the Navy Canal. These improvements include the construction of culverts under
South Street and Museum Road to d o w stormwater to flow to low areas and equalize. This
0 improvement will also provide water quality improvements as well. The estimated cost of this
improvement is about $210,000.
A culvert to enclose the Navy Canal as it passes through the ridge, to eliminate seepage of
groundwater into the Nova Canal system, is recommended, but costly. The estimated cost
of this recommended improvement is $1,500,000. However, this base flow from the Navy
Canal reduces the usable capacity of the land for runoff conveyance. The reduction of base
flow makes conveyance capacity available for stormwater runoff.
The recommended structural improvements for the Airport Planning Area are summarized in
Table 5-2.
5.4.4 Reed Canal Planning Area
The Reed Canal Planning Area is the most flood prone area in the Nova Canal system
watershed. Improvements in the Airport Planning Area should aid to lower the peak flood
stages in the Nova Road Canal Central reach in the northern part of the City of South
Daytona, but will not lower stages hrther south between Big Tree Road and Reed Canal
Road. To reduce the stages in this reach of the canal, a diversionldetention basin is
recommended to be constructed at the southeast comer of Nova Road and Big Tree Road,
to take runoff that presently flows fiom the west down Big Tree Road. This detention area,
in conjunction with the improvements discussed previously in the Airport Planning Area,
reduces flood stages between Big Tree Road and Reed Canal Road by between 0.5 and 1.0
feet. These improvements would prevent flood waters fiom overtopping Nova Road in the
part of the planning area where the worst flooding occurs when the upcoming improvements
by FDOT are completed. The estimated cost to construct the Big Tree Road Detention
Facility is about $2.2 million.
- Even with the canal contained in its banks by the storage provided by the Big Tree Road
Detention Facility, the 100-year event- flood stages are still higher than many of the finished
floors of homes in the neighborhoods adjacent to Nova Road Canal Central in South Daytona.
To prevent the Nova Road Canal Central fiom backflowing into these neighborhoods, the
system was modeled with backflow preventers in the discharge pipes fiom these
neighborhoods in South Daytona. The estimated cost of bacldlow preventers is
approximately $5,000 for each 24-inch pipe. Backflow preventors are not recommended as
an improvement except as a last resort. Typically, runoff trapped behind the closed valve
requires that either a pump station be constructed, or specsc houses be flood proofed. Since
there are other alternatives that can accomplish the same function without a loss of flood plain
storage, backflow preventors should only be utilized sparingly if at all.
Flooding problems within the Reed Canal Planning Area are also associated with the Stevens
Canal. The recommended improvement for Stevens Canal include doubling the width of the
ditch between Big Tree Road and Reed Canal Road, but keeping the existing pipes. For
regulatory purposes, compensating for this additional flow will require Stevens Canal to be
connected to a shell pit near Nova Road, to provide storage and treatment. The estimated
cost to construct these improvements is about $285,000.
Source reduction to reduce canal water levels and other water quality improvements in the
Reed Canal Planning Area are similar to the recommendations for the 1 lth Street Canal
Planning Area. West ofNova Road, in areas with elevations above 15.0 NGVD, exfiltration
systems or swales in existing developments without stormwater management facilities are
recommended. In several instances, the density of existing development is very high and there
are no available areas for swales. Swale and exfiltration systems also reduce the flow in the
Nova Road Canal Central reach will also be achieved, which is a water quantity benefit and
reduces the cost of downstream improvements. The cost of exfiltration systems and swales
0 , . in this planning area is estimated at $2,000,000.
For the area between Nova Road and the U.S. Highway No. l/FEC Railroad, treatment train
technologies are recommended if efficiencies can be proven to be acceptable. An allowance
of $4 million for the estimated cost of treatment train technology has been assumed for the
purposes of this study. If'treatment train technology cannot adequately provide the needed
treatment efficiencies, the construction of wet detention facilities on existing developed
parcels is recommended. The Big Tree Road Detention Facility described above will help to
achieve water quality benefits, as well. The cost of this facility is about $2.2 million. Another
recommended improvement in this immediate area is the diversion of the ditch system along
Big Tree Road east of Nova Road, through three existing man-made lakes. The cost of this
improvement was estimated at $120,000. Runoff from subdivisions west of Nova Road can
be diverted by a collector storm sewer system to Reed Canal Lake. The estimated cost of this
conveyance improvement is $1 20,000.
0 Another water quality improvement recommended for the Reed Canal Planning Area is the
1' construction of a detention basin on the property behind the Rinker Material Company site
in South Daytona. This facility can also be used for handling and treating sediments that have
been dredged fiom Reed Canal, and for a detention basin. The cost of this facility was
estimated as $2.1 million.
The recommended structural improvements for the Reed Canal Planning Area are summarized
by Table 5-3.
5.4.5 Halifax Canal Planning Area
The Halifax Canal Planning Area has several water quantity problem areas that can be
attributed to the canal overtopping its banks and inundating property surrounding the canal.
Based on the results of the SWMM model of the Hahfax Canal and drainage evaluations
performed by others, the culvert located under Commonwealth Boulevard is recommended
0 to be replaced. The recommended improvement is a double 6' x 10' culvert, also
recommended previously by the City of Port Orange drainage consultant. The estimated cost
for this improvement is about $21 5,000.
Another recommended water quantity improvement for this are. is the raising of the elevation
of Dunlawton Boulevard near Ruth Avenue, to ensure that this evacuation route is open
during severe storm events. The estimated cost for this recommended improvement is
about $41 0,000.
Water quality improvements recommended for the Halifax Canal Planning Area differ fiom
the recommendations for the 1 lth Street Canal and Reed Canal Planning Areas. There are
only limited areas of the Halifax Canal Planning Area that have soils and groundwater
characteristics that are amenable to dry retention areas, swales, or exfiltration trenches.
Where it is possible, these source reduction improvements should be utilized. The estimated
cost of edltration systems in this planning area is about $775,000 and for swales is about
$430,000.
Where the canal alignment shifts to the east, the ridge area with well-drained soils that is
amenable to exfiltration systems and swales no longer falls within the drainage basin. The
Halifax Canal drains an area of tidally influenced flood plain that is densely developed in
certain areas. Because most of this development occurred before stormwater treatment was
required, these areas are sources of urban stormwater runoff pollution. The water table is
high in these areas during the wet season, meaning water quality improvements are limited
to treatment train technology and will be relatively expensive. It may be more economical in
the long run to purchase blocks of developed land in the lowest elevation areas and construct
detention pond facilities. However, a cost of $2 million was assumed for treatment train
technology improvements in the Halifax Canal Planning Area.
The recommended structural improvements for the Halifax Canal Planning Area are
summarized in Table 5-4.
5.4.6 Eastside Planning Area
There were no water quantity problem areas identified in the Eastside Planning Area. The
sub-basins in this planning area are directly connected to the Halifax River through storm
sewer systems and only contribute runoff to the Nova Canal system during large storm events.
However, water quality improvements in this area should have a high priority. The sub-basins
in this planning area contribute the highest pollutant loads of any planning area within the
watershed. Almost all of the pollutants are directly discharged into the Halifax River because
all of the sub-basins contain a large percentage of directly connected impervious area (DCIA).
To reduce both pollutant loads and freshwater flows, exfiltration systems on private
commercial property along U.S. Highway No. 1 are recommended. The cost of these
exfiltration systems is estimated to be about $600,000.
In the other parts of this planning area, treatment train technology improvements are
recommended. However, the area is densely developed with a high percentage of commercial
land use. Although the utilization of treatment train facilities may need to be intensive, and
annual maintenance costs high, it was not considered practical that commercial property
would be purchased and converted to stormwater treatment facilities. Additionally, since in-
river detention facilities have not in the past been permitted by the regulatory agencies, they
were not recommended except as presented below. In-river facilities were recommended in
the City of Daytona Beach Stormwater master Plan (1989). The estimated cost of treatment
train technology facilities in this planning area is $1.0 million.
The Wilder Boulevard sub-basin outfall has an area near the discharge point that may be
suitable for a detention facility. Part ofthis area is salt marsh which would require mitigation
through restoration of an adjacent area that has been used for the deposition of spoil from a
dredging project. Without the mitigation opportunity, this improvement would not be
recommended. However, there are other few proven alternatives for treatment in this basin.
The estimated cost of this detention facility including mitigation is about $460,000.
The recommended structural improvements for the Eastside Planning Area are summarized
by Table 5-5.
5.4.7 Additional Outfalls
Several of the recommendations discussed previously reduce flood stages for specific portions
of the Nova Canal, but do not reduce flood stages across the entire length of the Nova Canal
system. Therefore alternatives which result in a significant decrease in flood stages
throughout the system were analyzed. To obtain the maximum reduction in flood stages,
additional outfalls would need to be added at many locations along the length of the Canal.
However, this results in a very large increase in the peak flow and volume of freshwater being
discharged to the Halifax River, and it will not eliminate all of the problems. Construction
of enough outfalls of sacient size to achieve complete flood protection for all structures in
the watershed would also be prohibitively expensive and would result in a fbrther
deterioration of the water quality of the Halifax River. Therefore, this alternative is not
recommended for implementation.
A modification of the above concept in which additional outfalls are added but the overall
volume and peak flow are not increased above the current rate and volume was developed.
As analyzed, this alternative included the addition of two outfalls connecting the middle
portion of the Nova Canal to the Halifax River with control structures installed at all
discharge points, including the existing ones. The goal of this improvement is to reduce flood
stages along Nova Canal without an increase in the 25-year storm event peak flow or
volume. To achieve this goal detention ponds with control structures were also needed
before the flows could be discharged from the new outfalls. For the existing 1 Ith Street
outfall the previously recommended ponds along the North and South Railroad Canals are
needed along with a control structure in the main reach of the 1 lth Street Canal to reduce the
0 . . .- . . existing peak flow being discharged to the Halifax River. For Reed Canal, the previously
recommended pond to the southeast of Reed Canal Road and the FEC railroad is needed
along with a control structure in the main reach of the Reed Canal.
With the existing flows from the 1 lth Street Canal and Reed Canal reduced, the north Outfall
and South Outfall will need to be constructed as described in Chapter 4. Control structures
on these new outfds will atlow the discharge to be controlled so that the volume and rate of
flow can be held to the existing level, or less. With control structures on all outfalls, it will
be possible to reduce the discharge during periods of drought and dry seasons. This would
be beneficial to the surfjcial aquifer and to the Halifax River. If needed, the control structures
could then be opened so that flow is achieved during an extreme event. The control
structures would also serve to resist the tidal flow of the Halifax River into the Nova Canal
system. However, before these improvements can be constructed, a method of operating and
maintaining the control structures must be developed (see Chapter 7). The estimated cost of
all improvements associated with two additional outfalls but no increase in discharge is $37.6
d o n . A summary of the improvements included in this alternative is presented in Table 5-6.
When deciding whether or not to implement this improvement, several things must be
considered. First, adding two additional outfalls and associated wet detention facilities only
reduce the flood stage by about 1.0 to 1.5 feet during the 100-year storm event. This will not
completely eliminate flooding in the area between U.S. Highway No. 1 and Nova Road.
Some of the lowest developed properties will still have the potential to flood during extreme
storm events and should be flood-proofed, raised, or acquired. Second, there have already
been serious discussions regarding eliminating freshwater discharges to estuarine systems at
the regulatory agencies. To achieve an improvement in the water quality of the Halifax River,
the discharge of stormwater runoff to the Halifax River will have to be reduced significantly
if it cannot be eliminated. Other flood prevention solutions such as impervious area
reduction, purchasing tracts of low lying developed lands, and raising or flood-proofing
homes are also needed with the construction of additional outfalls, significantly increasing the
cost. Therefore, the construction of additional outfalls without an increase in discharge rate
is only recommended as a temporary solution, and is only recommended if a flow reduction
schedule is also adopted.
5.4.8 Land Acquisition
In Chapter 4, a prioritized list of existing vacant parcels was presented (Table 4-38). The cost
of purchasing all of the high priority parcels was estimated to be between $10 and $13
million. It is recommended that these parcels be acquired as soon as possible, as they may
become developed if not purchased in the near future. It is also recommended that
the medium priority parcels be considered fbrther for additional storage. It is also
recommended that a plan for restoration of the flood plain be developed that includes the
purchase of key developed parcels, which can also be used for water quality improvements
as described herein.
5.5 RECOMMENDATIONS SUMMARY
Recommended structural improvements which require the expenditure of capital funds, non-structural
improvements, and operation and maintenance improvements have been identified. The
recommendations in this report are the minimum that should be undertaken to protect property
and the remaining natural resources. The restoration of the canal to the original design cross
section and the cleaning of the culverts under road crossings is a primary O&M improvement
recommendation. Based on computer modeling, some of the problem areas can be attributed
to blocked pipes or canals. Rainfall that resulted from Tropical Storm Gordon produced flood
stages above those predicted by the SWMM model for a similar storm or in past drainage studies.
This implies that canal maintenance should be a priority. An engineered program for canal
maintenance will also improve water quality by allowing hture sediment to accumulate in the
canal at specific locations where it can be removed periodically and not be washed into the
Halifax River.
A summary of the recommended structural improvements that have been identified (except
additional outfalls) are presented as a Capital Improvements Program (CIP) in Table 5-7. As
can be seen, the total estimated cost of all structural improvements except additional outfalls
is approximately $3 1 million. Some of the improvements in Table 5-7 were needed with the
additional outfds to achieve a desirable level of flood stage reduction. If additional outfalls
are to be considered, an additional $28.5 million will need to be added to the $3 1 million of
improvements presented in Table 5-7. The estimated cost of purchasing significant existing
vacant parcels for flood plain protection is between $10 and $1 3 million. Therefore, the total
cost for the improvements presented in this report, if hlly implemented, is about $70 million.
To obtain an estimate of the revenue generating capability of the Nova Canal system watershed,
it was assumed that all equivalent residential drainage units (EDU) within the watershed would
be charged $3/per month per EDU. Under this assumption approximately $2 million per year
is generated in this watershed. At this rate of collection, if all money was available for improvements,
the structural improvements recommended herein could be constructed in about 35 years.
As a comparison, if $1 million is used each year to raise the existing homes that were flooded
by Tropical Storm Gordon, it would take 10 years to raise 500 homes. There is no annual
maintenance cost associated with a house that has been raised but flooded roads will still remain.
Most likely, a combination of the structural improvements presented, raising some homes, and
increasing the drainage fee in the Nova Canal system watershed will be needed to alleviate the
flooding problems in the watershed and improve the water quality in the Halifax River.
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