Jetty_Park_Stormwater_Calculations.pdf
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- Solicitation number
- RFQ-25-4
- Issued by
- Florida
About this file
This document is a Stormwater Management System Calculations report prepared by Construction Engineering Group for the St. Johns River Water Management District, focusing on a dry retention treatment system for the Jetty Park project located in Port Canaveral, Florida. The report details a proposed stormwater management solution required to compensate for a parking area expansion, utilizing a dry retention system that will provide treatment for Basin01, Basin02, and Basin05. The project involves redesigning an existing stormwater pond to meet the requirements of previously permitted SJRWMD Permit Nos. 16830-4 and 16830-3, with a new control structure replacing a damaged existing one.
The calculations demonstrate that the proposed dry retention area will recover within 17 hours, which is well within the allowed 72-hour period, and will provide over 100% of the required treatment volume. The total project area includes 3.18 acres of impervious surface and 5.39 acres of pervious surface, with a total basin area of 8.57 acres. The total required treatment volume is 25,755 cubic feet, with the design providing 25,903 cubic feet of treatment volume. The soils report indicates an average seasonal high water table of 2 feet, and the design satisfies all requirements of both the St. Johns River Water Management District and the Canaveral Port Authority.
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STORMWATER MANAGEMENT
SYSTEM CALCULATIONS
JETTY PARK
STORMWATER
PREPARED FOR:
ST. JOHNS RIVER WATER MANAGEMENT DISTRICT
PREPARED BY:
2651 W. Eau Gallie Blvd.
Melbourne, FL 32935
Board of Professional Engineering License No. 0008097
David M. Tom, P.E.
FL PE #56699
AUGUST 10, 2017 CEG No. 160215 jmannon Image jmannon Typewritten Text 8/18/17
INTRODUCTION
This report includes detailed points on compliance and design calculations for the proposed dry retention treatment system required to compensate for the pond area removed for the expansion of the parking area. The proposed project is located in Port Canaveral, Florida as identified on the attached Figure 3.
The proposed location for the parking expansion is between the playground area and the existing drive aisles. The proposed dry retention system meets the same requirements as the previously permitted SJRWMD Permit Nos. 16830-4 and 16830-3.
The required treatment volume is calculated as treatment volume only, no impaired water body calculations are required, and no modeling of storm events is required for direct discharge into the Atlantic Ocean. The dry retention system will provide over 100% of the required treatment volume. MODRET Version 6.1 for is the software utilized to demonstrate the dry retention system recovers the provided treatment volume within the required 72-hour period. The proposed dry retention pond will provide treatment for Basin01, Basin02, and Basin05. Basin01 is consistent with previously permitted with revised impervious area to account for new parking area. The pond provides compensatory treatment volume for Basin02 and the proposed bait shop along the west side of Basin05 as calculated.
Basin05 has been reduced, with the previously constructed boat launch area removed as it no longer drains into this system. Figure 1 shows the revised Post- Development Plan with Basin01 and Basin05 combined. Basin02 is not shown since it is consistent with the previously approved design. Figure 2 shows the previously approved Post-Development Plan along with the area that was removed from Basin05. The redesigned dry pond will utilize the existing outfall pipe, but will provide a new control structure as the existing one has been damaged.
The soils report from the previously approved stormwater calculations was utilized to determine the seasonal high water table, and infiltration rates. The average seasonal high water table is 2 feet, consistent with the previous model.
ANALYSIS OF RESULTS
The enclosed MODRET model results demonstrate that the dry retention area recovers within 17 hours, which is less than the allowed 72-hour period.
Therefore, the proposed design satisfies all requirements of the St. Johns River Water Management District and the Canaveral Port Authority.
PROJECT: JETTY PARK STORMWATER
DATE: Aug-17
ENGINEER: Cydney Sims
Elevations: Finished floor NA feet
Pond top of bank 6.00 feet
Pond bottom 5.00 feet
Overflow weir invert 6.00 feet
Post-Development Basin Data:
Type Area (acres)
Impervious 3.18
Pervious 5.39
Total 8.57
Elevation Area Avg. Area Volume Sum. Volume
(Feet) (Sq. Ft.) (Sq. Ft.) (Cu. Ft.) (Cu. Ft.)
6.00 28,429 25,903
25,903 25,903
5.00 23,376 0
Treatment Volume:
1) Volume from 0.5 inch of runoff from total area
(0.5 in.)(total area)(43,560 sf/ac) = 15,555 cu. ft.
12 in/ft
2) Volume from 1.25 inches of runoff from impervious area
(1.25 in.)(imperv. area)(43,560 sf/ac) = 14,429 cu. ft.
12 in/ft
3) Therefore, greater volume = 15,555 cu. ft.
Total Required Treatment Volume Basin01 and Basin05 = 15,555 cu. ft.
Total Required Treatment Volume Basin02 = 10,200 cu. ft.
Total Required Treatment Volume = 25,755 cu. ft.
Total Provided Treatment Volume = 25,903 cu. ft.
BASIN DATA AND CALCULATIONS
Stage/Storage Volume:
Basin01 & Basin05
BASIN DATA AND CALCULATIONS
DRY RETENTION RECOVERY MODELING
MODRET
SUMMARY OF UNSATURATED & SATURATED INPUT PARAMETERS
PROJECT NAME : Jetty Park Stormwater
POLLUTION VOLUME RUNOFF DATA USED
UNSATURATED ANALYSIS INCLUDED
Pond Bottom Area 23,376.00 ft²
Pond Volume between Bottom & DHWL 25,755.00 ft³
Pond Length to Width Ratio (L/W) 4.00
Elevation of Effective Aquifer Base -7.50 ft
Elevation of Seasonal High Groundwater Table 2.00 ft
Elevation of Starting Water Level 5.00 ft
Elevation of Pond Bottom 5.00 ft
Design High Water Level Elevation 6.00 ft
Avg. Effective Storage Coefficient of Soil for Unsaturated Analysis 0.18
Unsaturated Vertical Hydraulic Conductivity 13.00 ft/d
Factor of Safety 2.00
Saturated Horizontal Hydraulic Conductivity 13.00 ft/d
Avg. Effective Storage Coefficient of Soil for Saturated Analysis 0.21
Avg. Effective Storage Coefficient of Pond/Exfiltration Trench 1.00
Hydraulic Control Features:
Top Bottom Left Right
Groundwater Control Features - Y/N N N N N Distance to Edge of Pond 0.00 0.00 0.00 0.00 Elevation of Water Level 0.00 0.00 0.00 0.00
Impervious Barrier - Y/N N N N N Elevation of Barrier Bottom 0.00 0.00 0.00 0.00
Analysis Date: 8/11/2017
TIME - RUNOFF INPUT DATA
PROJECT NAME: JETTY PARK STORMWATER
STRESS
PERIOD
NUMBER
INCREMENT
OF TIME
(hrs)
VOLUME
OF RUNOFF
(ft³)
Unsat 1.99 12,623.04
1 1.00 13,279.96
2 8.63 0.00
3 8.63 0.00
4 8.63 0.00
5 8.63 0.00
6 8.63 0.00
7 8.63 0.00
8 8.63 0.00
9 8.63 0.00
Analysis Date: 8/11/2017
SUMMARY OF RESULTS
PROJECT NAME : Jetty Park Stormwater
CUMULATIVE
TIME
(hrs)
WATER
ELEVATION
(feet)
INSTANTANEOUS
INFILTRATION
RATE (cfs)
AVERAGE
INFILTRATION
RATE (cfs)
CUMULATIVE
OVERFLOW
(ft³)
Analysis Date: 8/11/2017
00.00 - 0.00 2.000 0.000 *
0.00000
0.00 2.000 1.55724
1.27816
2.99 5.471 0.99908 0.00
0.19501
11.62 5.236 0.16257 0.00
0.13012
20.25 5.079 0.11359 0.00
0.09707
26.06 5.000 0.08770 0.00
0.07834
37.50 4.867 0.07239 0.00
0.06644
46.12 4.787 0.06228 0.00
0.05811
54.75 4.717 0.05500 0.00
0.05189
63.37 4.655 0.04946 0.00
0.04703
72.00 4.598 0.00
Maximum Water Elevation: 5.471 feet @ 2.99 hours Recovery @ 26.057 hours
* Time increment when there is no runoff
Maximum Infiltration Rate: 4.288 ft/day
EXHIBITS
csims Polygon csims Callout
THIS AREA WAS REMOVED AND IS NOW INCLUDED IN THE NEW BOAT RAMP
| 2017-08-18T12:54:33-0400 | |
| David M. Tom, PE |
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