HomeMy WebLinkAbout09 11 2009 St Johns River Water Mgmt District Permit 40-061-68172-12 Stormwater Master PlanSt. Johns River Water Management District
Environmental Resource Permit Application
Stormwater Report
for
Sebastian Municipal Airport
Stormwater Master Plan Update
RAI Response #2
SEBAS-TLNN
MUNICIPAL AIRPORT
August 2009
Index and Certification Page
St. Johns River Water Management District
Environmental Resource Permit Application
Drainage Report
Stormwater Master Plan Update
August 17, 2009
Drainage Report Narrative & Figures
Drainage Computations
24 Pages
Appendix B
Project Plans Appendix D
Patricia Therrien
State of Florida P.E. Number 52120
THE LPA GROUP INCORPORATED
615 Crescent Executive Court, Suite 200
Orlando, FL 32817
407-306-0200/0460(Fax)
FL Registration 0004307
Addendum to Stormwater Master Plan Update
Table of Contents
Introduction.......................................................................................................... 3
Soils / Groundwater Information........................................................................4
Floodplain / Wetland Information.......................................................................5
ExistingConditions.............................................................................................5
Stormwater Management....................................................................................5
Proposed Conditions and Analysis...................................................................7
WaterQuality.....................................................................................................10
Summary............................................................................................................13
Permit Application.............................................................................Appendix
A
Drainage Computations....................................................................Appendix
B
• Attenuation Summary
• Proposed Conditions Data
o Curve Number Calculation
o Stage -Storage Table
o Phosphorus Loading Analysis
• Existing Conditions ICPR Input / Output
o Input Data
o Node Minimum / Maximum
o Basin Summary Report
• Proposed Conditions ICPR Input / Output
o Input Data
o Node Minimum / Maximum
o Basin Summary Report
• Supplemental Information
Construction Plans............................................................................Appendix D
fl
Figures
Figure No. Description
1
Aerial Map
2
Quadrangle Map
3
Soils Map
4
100-year Flood FEMA Map
5
FLUCSFS Land Use Map\
5a
Verified Land Use and Cover Map
6
Pre -Development Drainage Map
7
Post -Development Drainage Map
8
Ditch Exhibit
9
Surface Waters
Tables
Table No. Description Page
1
Summary of Soils Information ................................... 4
2
Summary of Drainage Areas ..................................... 8
3
Summary of Project Area .......................................... 9
4A
Summary of Treatment Volume ...............................
10
4B
Summary of Treatment Volume ...............................
10
4C
Summary of Treatment Volume ...............................
11
4D
Summary of Treatment Volume ...............................
11
5
Summary of Basins .................................................
12
6
Summary of Tailwater Conditions ............................
13
7
Summary of Peak Stages ........................................
14
8
Summary of Peak Flows ..........................................
14
4
INTRODUCTION
The City of Sebastian wishes to provide improvements to the
Sebastian Municipal Airport (Airport). The improvements include
the construction of the Maintenance Building, extension of Airport
Drive East, and a stormwater management facility. Figure 1
shows a location map for the site and Figure 2 is the USGS quad
map. This site is within the jurisdictional limits of Indian River
County and the St. Johns River Water Management District
(SJRWMD). The existing golf course ponds (Pond 1 and Pond 3)
and two additional dry retention ponds will be used to provide
treatment and attenuation for the Stormwater Master Plan Update,
which includes current proposed development of Airport Drive
East and Maintenance Building which has been previously
permitted under Permit No. 40-061-68172-14. Please see Figure
7 Proposed Drainage Map.
The Airport is located in Sebastian, Florida (Indian River County)
in Section 22, Township 30 South, Range 38 East and Sections
28 and 29, Township 31 South, Range 38 East. Roseland Road
borders the site to the west and Airport Drive East to the
southeast. The Airport is located approximately one mile west of
the Indian River and 600 feet east of the South Prong of the
Sebastian Creek.
The total property area for the Airport is approximately 615.97
acres. The project acreage for which this permit modification
application is sought is approximately 86.24 acres. The proposed
impervious area for which the permit is sought is approximately
24.97 acres, included in Basins Airport Drive East A, Airport Drive
East B, Airport Drive East C, Maintenance Building A,
Maintenance Building B, Runway Basin, Depression 3, Hangar A,
Pond 1, and Pond 3 only. This acreage includes previously
permitted Airport Drive East Extension and Maintenance Building
(Permit No. 40-061-68172-14).
The site contains a number of small ditch systems. Some of these
ditch systems are piped to or outfall directly to the Sebastian
Creek west of the Airport. Other ditches drain off the property to
the east. There are also a number of low areas throughout the site
that do not drain off the Airport property during the 25-year 24-
hour storm event. The permitting for these ditches was not found
in SJRWMD or the Florida Department of Environmental
Protection databases.
Stormwater runoff from Airport Drive East A and Airport Drive East
B will collected into two dry retention ponds (Airport Drive East A
Pond and Airport Drive East B Pond) which will provided treatment
and attention. The two dry retention ponds will drain through the
existing double 6" metal pipes and will be conveyed to golf course