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STORMWATER MANAGEMENT REPORT for 156 East Commodore Boulevard Warehouse Block 2202 Lot 3
JACKSON TOWNSHIP OCEAN COUNTY NEW JERSEY
PREPARED BY:
PROFESSIONAL DESIGN SERVICES, L.L.C. 1245 AIRPORT ROAD SUITE 1 LAKEWOOD, NJ 08701 732-363-0060 PDS Ref. No. 320157
Graham J. Macfarlane, P.E., C. M.E. NJ License No. 37110
Graham J. Macfarlane, P.E., C. M.E.
December 9, 2025
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CONTENTS
I PROJECT DESCRIPTION ..... 1 II EXISTING HYDROLOGY AND SOILS ..... 2 III REGULATORY STANDARDS ..... 3 IV METHODOLOGY ..... 7 V STORMWATER MANAGEMENT PLAN ..... 9
APPENDICES
PRE-DEVELOPED CALCULATIONS
POST-DEVELOPED CALCULATIONS
COLLECTION SYSTEM CALCULATIONS
SOIL EROSION CALCULATIONS
GROUNDWATER MOUNDING
LIST OF FIGURES
ROAD MAP
TOPOGRAPHIC MAP
SOILS MAP
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I PROJECT DESCRIPTION
Development of the subject premises known as Block 2202 Lot 3 within Jackson Township, Ocean County, NJ is proposed. The subject parcel encompasses a total land area of approximately 2.2 acres.
It is proposed to develop the site with a new multi-tenant warehouse building in accordance with the Land Use and Development Regulations of Jackson Township. Construction of a Stormwater Management system is proposed for compliance with current regulations of Jackson Township, Ocean County and the Ocean County SCD, as well as the NJ Stormwater Management Rules, NJAC 7:8. This report outlines the methodologies and results for management of the increased stormwater runoff created as a result of the development.
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II EXISTING HYDROLOGY & SOILS
The project site lies within the watershed of the South Branch of the Metedeconk River. Figure 2 is a copy of the USGS Quadrangle Topography Map with the site located. The site generally slopes from the west to east. The existing elevations range from about 110 feet above MSL to 120 feet above MSL. Figure 1 is a copy of the site's Location Map. Figure 2 is a copy of the USGS Quadrangle Topography Map with the site located. Development of the site is not restricted by the presence of freshwater wetlands, flood hazard area or Category One Riparian buffers. According to the Ocean County Soil Survey, the following soil types exist on the project site:
Soil Type% SlopeDepth to SHWT*HSG*
LasB - Lakewood Sand2-5>6 feetA
BerAr- Berryland Sand0-20-6 inchesA/D
Lakewood sand would typically comprised of 90% sand grains. Permeability of the series is rapid, and greater than 2 inches per hour; the series is considered excessively drained. The soil does not retain water for long periods of time. The soil series is not associated with flood plains, and depth to seasonal high water table is typically greater than 6 feet.
Based on the mapping, Berryland Sand is also depicted on site. This soil series is typically poorly drained, and could impose limitations on development based on high water table. However, the site specific soils investigations did not reveal these findings. We would defer to the site specific data and evaluations in lieu of the published data in the Soil Survey.
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PDS PROFESSIONAL DESIGN SERVICES, L.L.C. CONSULTING ENGINEERS, LAND SURVEYORS, PLANNERS, ENVIRONMENTAL SCIENTISTS, CONSTRUCTION SERVICES 1245 AIRPORT ROAD, SUITE 1, LAKEWOOD, NEW JERSEY 08701 PHONE 732 363 0060 FAX 732 363 0073 ENGINEERING@PDS-NJ.COM WWW.PDS-NJ.COM NEW JERSEY STATE BOARD OF P.E. & L.S. CERTIFICATE OF AUTHORIZATION NO. 24GA28125400
DCATION MAF FOR BLOCK 2202 LOT 3
TOWNSHIP OF JACKSON OCEAN COUNTY NEW JERSEY
DATE: 08/25/2025
DRAFTED BY: BK DATE: 08/25/2025 PROJECT: 320157
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SCALE IN FEET
PROFESSIONAL DESIGN SERVICES, L.L.C.
CONSULTING ENGINEERS, LAND SURVEYORS, PLANNERS, ENVIRONMENTAL SCIENTISTS, CONSTRUCTION SERVICES AIRPORT ROAD, SUITE 1, LAKEWOOD, NEW JERSEY 0870 PHONE 732 363 0060 FAX 732 363 0073 ENGINEERING@PDS-NJ.COM WWW.PDS-NJ.COM NEW JERSEY STATE BOARD OF P.E. & L.S. CERTIFICATE OF AUTHORIZATION NO. 24GA28125400
QUAD MAP
FOR
BLOCK 2202 LOT 3
TOWNSHIP OF JACKSON OCEAN COUNTY NEW JERSEY
DATE: 08/25/2025
DRAFTED BY: BK
PROJECT: 320157
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PDS
PROFESSIONAL DESIGN SERVICES, L.L.C. CONSULTING ENGINEERS, LAND SURVEYORS, PLANNERS, ENVIRONMENTAL SCIENTISTS, CONSTRUCTION SERVICES 1245 AIRPORT ROAD, SUITE 1, LAKEWOOD, NEW JERSEY 08701 PHONE 732 363 0060 FAX 732 363 0073 ENGINEERING@PDS-NJ.COM WWW.PDS-NJ.COM NEW JERSEY STATE BOARD OF P.E. & L.S. CERTIFICATE OF AUTHORIZATION NO. 24GA28125400
SOILS MAP
FOR
BLOCK 2202 LOT 3
TOWNSHIP OF JACKSON OCEAN COUNTY NEW JERSEY
DRAFTED BY: BK DATE: 08/25/2025 PROJECT: 320157
DATE: 08/25/2025
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Ⅲ
REGULATORY STANDARDS
A. Applicable Regulations
All increased stormwater runoff resulting from the proposed development must be managed both qualitatively and quantitatively in accordance with New Jersey Regulations.
The Flood Hazard Area, Freshwater Wetland Regulations and Residential Site Improvement Standards (RSIS), as administered by the New Jersey Department of Environmental Protection (NJDEP) requires the utilization of best available technology to minimize the amount of stormwater runoff, maintain existing onsite infiltration, simulate natural drainage systems and minimize the discharge of pollutants to ground or surface waters. The overall goal of the post-construction stormwater management system design shall be to meet the erosion control, groundwater recharge, stormwater runoff quantity and quality standards at N.J.A.C. 7:8-5.4 and 5.5.
The stormwater management must be designed to:
Reduce flood damage, including damage to life and property;
Minimize, to the extent practical, any increase in stormwater runoff from any new development;
Reduce soil erosion from any development or construction project;
Assure the adequacy of exiting and proposed culverts and bridges, and other in-stream structures;
Maintain groundwater recharge;
Prevent, to the greatest extent feasible, an increase in nonpoint pollution;
Maintain the integrity of stream channels for their biological functions, as well as for drainage;
Minimize pollutants in stormwater runoff from new and existing
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development in order to restore, enhance and maintain the chemical, physical, and biological integrity of the waters of the State, to protect public health, to safeguard fish and aquatic life and scenic and ecological values and to enhance the domestic, municipal, recreational, industrial and other uses of water; and
Protect public safety through the proper design and operation of stormwater management basins.
Utilize Green Infrastructure Standards outlined in NJAC 7:8-5.3 to satisfy groundwater recharge and stormwater runoff quality standards.
Analysis will utilize the New Jersey Stormwater Best Management Practices (BMP) Manual as guidance. Overall stormwater management shall take into account the following:
Existing site conditions, including: environmentally critical areas; wetlands; flood prone areas; slopes; depth to SHWT; soil type; permeability; texture; drainage area and drainage patterns; and the presence of limestone.
Designed to minimize maintenance and ensure proper functioning.
Designed, constructed and installed to be strong, durable and corrosion resistant.
Designed to meet minimum safety standards.
B. Design and Performance Standards
1. Erosion Control
The minimum design and performance standards for erosion control are those established under the Soil Erosion and Sediment Control Act, N.J.S.A. 4:24-39 et seq. and implementing rules.
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2. Groundwater Recharge
The minimum design and performance standards for groundwater recharge require compliance with either of the following:
Demonstrate through hydrologic and hydraulic analysis that the site and its stormwater management measures maintain 100 percent of the average annual pre-construction groundwater recharge volume for the site.
Demonstrate through hydrologic and hydraulic analysis that the increase of stormwater runoff volume from pre-construction to post-construction for the two-year storm is infiltrated.
3. Runoff Quantity
In order to control stormwater runoff quantity impacts one of the following must be demonstrated:
Demonstrate through hydrologic and hydraulic analysis that for stormwater leaving the site, post-construction runoff hydrographs for the 2, 10 and 100-year storm events do not exceed, at any point in time, the pre-construction runoff hydrographs for the same storm events;
Demonstrate through hydrologic and hydraulic analysis that there is no increase, as compared to the pre-construction condition, in the peak runoff rates of stormwater leaving the site for the 2, 10 and 100-year storm events and that the increase volume or change in timing of stormwater runoff will not increase flood damage at or downstream of the site. This analysis shall include the analysis of impacts of
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existing land uses and projected land uses assuming full development under existing zoning and land use ordinances in the drainage area;
Design stormwater management measures so that the post-construction peak runoff rates for the 2, 10 and 100-year storm events are 50, 75 and 80 percent, respectively, of the pre-construction peak runoff rates. The percentages apply only to the post-construction stormwater runoff that is attributable to the portion of the site on which the proposed development or project is to be constructed.
Water Quality
Stormwater management measures shall be designed to reduce the post-construction load of total suspended solids (TSS) in stormwater runoff generated from the water quality design storm by 95 percent of the anticipated load from the development site expressed as an annual average, since the site is located within the watershed of a Category One Waterway.
Direct run-off from building roof tops is not considered contaminated since it has not contacted the pavement or the ground surface, and is not subject to satisfaction of the TSS removal criteria.
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IV METHODOLOGY
The overall design will control stormwater runoff and pollutants closer to their source while providing site design measures that can significantly reduce the overall impact of land development on stormwater runoff as required by the Stormwater Management Rules. The methodology typically used to estimate the stormwater runoff peak flows and volumes for the required storm events is the 24-hour storm using the rainfall distribution recommended by the U.S. Department of Agriculture Soil Conservation Service as defined in Technical Release - 55 (TR-55) dated June 1986. The time of concentrations utilized will be calculated for each contributory area utilizing the TR-55 methodology. For the purpose of calculating runoff coefficients and groundwater recharge, a preconstruction condition of a site or portion thereof are assumed to be in good condition. A runoff coefficient or a groundwater recharge land cover for an existing condition may be used on all or a portion of the site if the hydrologic condition has existed on the site or portion of the site for at least five years without interruption prior to the time of application. The runoff computations shall account for all significant land features and structures, such as ponds, wetlands, depressions, hedgerows, or culverts, that may reduce pre-construction stormwater runoff rates and volumes. In computing stormwater runoff from all design storms, the computations consider the relative stormwater runoff rates and/or volumes of pervious and impervious surfaces separately to accurately compute the rates and volume of stormwater runoff from the site. The water quality design storm is 1.25 inches of rainfall in two hours. Water quality calculations shall take into account the distribution of rain from the water quality design storm, as reflected in the Stormwater Rules. All hydrologic and flood routing computations will utilize the HydroCad Stormwater
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Modeling Software. The stormwater drainage collection system will be designed in accordance with RSIS standards. The Rational Formula was used to compute peak runoff rates for design of the proposed internal collection system. A 10 year frequency storm was used for design as required by RSIS and the rainfall intensities were obtained from the NJDEP Rainfall Intensity Curves. The sub-areas tributary to each inlet are shown on the Drainage Area Plans. Soil erosion and sediment controls will also be employed as required by the "Standards for Soil Erosion and Sediment Control in New Jersey."
Copies of the TR-55 hydrologic computations, detention basin routings, and Rational Formula computations are contained within the appendices of this report.
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V STORMWATER MANAGEMENT PLAN
Erosion Control
The project complies with the "New Jersey Standards for Soil Erosion and Sediment Control". Certification for the project is required from the Ocean County Soil Conservation District.
Groundwater Recharge
All increased run-off from the 2 year storm event will recharge the groundwater through the stormwater management system. In accordance with the NJ Stormwater Management Rules, NJAC 7:8-5.4, the project shall maintain 100 percent of the average annual pre-construction groundwater recharge volume for the site, or demonstrate that the increase of stormwater run-off from pre-construction to post-construction for the two year storm is infiltrated.
As shown in the flood routings, the site will not produce any additional run-off during the 2 year storm event, and will provide for full recharge from any additional impervious surfaces. All run-off generated will be infiltrated on site through the rain garden/bio-retention facility and small scale infiltration basin. Since the design provides groundwater recharge of increased run-off from the 2 year storm event, the design complies with the applicable standard.
Runoff Quantity
Analysis of pre-developed conditions confirms that run-off from the project site is directed to the east property line.
The stormwater management plan consists of on-site collection system and a series of small-scale infiltration basins (SSIB), both surface and sub-surface. Pre-treatment
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forebay is provided for the surface SSIB's to provide water quality and TSS removal in accordance with adopted regulations. The overall system will maintain peak discharge rates to less than those required by State adopted Stormwater Management criteria. The following is a summary of the runoff from the site:
A. Pre-developed Conditions
Storm EventExist Peak Discharge from Site (CFS)Allowable Peak Discharge (CFS)
2 year1.430.71
10 year2.321.74
100 year5.234.18
C. Post-developed Conditions
Post-developed run-off rates are tabulated as follows:
Storm EventAllowable Permissible Peak Discharge (CFS)Post-Developed Discharge (CFS)Status
2 year0.710.24Complies
10 year1.740.95Complies
100 year4.183.71Complies
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Water Quality and Green Infrastructure
The project will allow for full infiltration from all run-off resulting from the Water Quality Design Storm. Accordingly, the project satisfies the requirement for water quality. The project complies with the applicable standards.
Green Infrastructure is complied with by using small-scale infiltration basins with pre-treatment forebay, and with direct contributory area to any component is limited to 2.5 acres (which is not required to include the component itself), and tabulated as follows:
IDDrainage AreaPre-treatment
SSIB #11.29 acresyes
SSIB #2 UG0.46 acresyes
SSIB #3 UG0.46 acresN/A for Rooftop
Maintenance
All components of the stormwater management system will be owned and maintained by the land owner. Refer to the Stormwater System Maintenance Plan for additional information.
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Time to Drain
Time to drain for each SSIB is tabulated as follows:
Structure IDVolume of Storage to First Outlet (CF)Outflow (CF/hr) @ 1.0 in/hrTime to Drain (hrs)
SSIB #13,54417021
SSIB #2 UG2,17821810
SSIB #3 UG4,79130815.5
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APPENDIX A PRE-DEVELOPED CONDITION CALCULATIONS
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Routing Diagram for PRE DEV Prepared by Professional Design Services, Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
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PRE DEV
Prepared by Professional Design Services Printed 12/31/2025
HydroCAD\circledR 10.20-6a s/n 02223\circledC 2024 HydroCAD Software Solutions LLC Page 2
Rainfall Events Listing
Event#Event NameStorm TypeCurveModeDuration (hours)B/BDepth (inches)AMC
12 YEARNOAA 24-hrDDefault24.0013.422
210 YEARNOAA 24-hrDDefault24.0015.382
3100 YEARNOAA 24-hrDDefault24.0019.482
Rainfall Events Listing
1 2 YEAR NOAA 24-hr D Default 24.00 1 3.42
2 10 YEAR NOAA 24-hr D Default 24.00 1 5.38
3 100 YEAR NOAA 24-hr D Default 24.00 1 9.48
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PRE DEV Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Area Listing (all nodes)
Area (acres)CNDescription (subcatchment-numbers)
0.11039>75% Grass cover, Good, HSG A (1S)
0.78072Dirt roads, HSG A (1S)
0.15096Gravel surface, HSG A (2S)
0.30098Paved parking, HSG A (2S)
1.08030Woods, Good, HSG A (1S)
2.42056TOTAL AREA
Printed 12/31/2025 Page 3
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PRE DEV Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Soil Listing (all nodes)
Area (acres)Soil GroupSubcatchment Numbers
2.420HSG A1S, 2S
0.000HSG B
0.000HSG C
0.000HSG D
0.000Other
2.420TOTAL AREA
Printed 12/31/2025 Page 4
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PRE DEV
Prepared by Professional Design Services Printed 12/31/2025
HydroCAD\circledR 10.20-6a s/n 02223\circledC 2024 HydroCAD Software Solutions LLC Page 5
Ground Covers (all nodes)
HSG-A (acres)HSG-B (acres)HSG-C (acres)HSG-D (acres)Other (acres)Total (acres)Ground CoverSubcatchment Numbers
0.1100.0000.0000.0000.0000.110>75% Grass cover, Good1S
0.7800.0000.0000.0000.0000.780Dirt roads1S
0.1500.0000.0000.0000.0000.150Gravel surface2S
0.3000.0000.0000.0000.0000.300Paved parking2S
1.0800.0000.0000.0000.0001.080Woods, Good1S
2.4200.0000.0000.0000.0002.420TOTAL AREA
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PRE DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 6
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS Runoff Area=1.970 ac 0.00% Impervious Runoff Depth>0.08" Flow Length=430' Tc=19.1 min CN=47 Runoff=0.03 cfs 0.012 af Subcatchment2S: IMPERVIOUS Runoff Area=0.450 ac 66.67% Impervious Runoff Depth>2.84" Flow Length=280' Tc=2.6 min CN=97 Runoff=1.43 cfs 0.106 af Reach 3R: COMPOSITE Inflow=1.43 cfs 0.119 af Outflow=1.43 cfs 0.119 af Total Runoff Area = 2.420 ac Runoff Volume = 0.119 af Average Runoff Depth = 0.59" 87.60% Pervious = 2.120 ac 12.40% Impervious = 0.300 ac
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PRE DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 1S: POROUS
Runoff = 0.03 cfs @ 14.19 hrs, Volume= 0.012 af, Depth> 0.08" Routed to Reach 3R : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
1.080 30 Woods, Good, HSG A
0.110 39 >75% Grass cover, Good, HSG A
0.780 72 Dirt roads, HSG A
1.970 47 Weighted Average
1.970 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
2.5 140 0.0350 0.94 Shallow Concentrated Flow, Woodland Kv= 5.0 fps
1.6 190 0.0150 1.97 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps
19.1 430 Total
15.0 100 0.0450 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.42"
Subcatchment 1S: POROUS
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PRE DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 1.43 cfs @ 12.10 hrs, Volume= 0.106 af, Depth> 2.84" Routed to Reach 3R : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.150 96 Gravel surface, HSG A
0.300 98 Paved parking, HSG A
0.450 97 Weighted Average
0.150 33.33% Pervious Area
0.300 66.67% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 180 0.0110 2.13 Shallow Concentrated Flow, Paved Kv= 20.3 fps
2.6 280 Total
1.2 100 0.0200 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
Subcatchment 2S: IMPERVIOUS
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PRE DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 9
Summary for Reach 3R: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.420 ac, 12.40% Impervious, Inflow Depth > 0.59" for 2 YEAR event Inflow = 1.43 cfs @ 12.10 hrs, Volume= 0.119 af Outflow = 1.43 cfs @ 12.10 hrs, Volume= 0.119 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 3R: COMPOSITE
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PRE DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 10
Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Printed 12/31/2025 Page 10 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S: POROUS Flow Length=430' Tc=19.1 min CN=47 Runoff=0.40 cfs 0.092 af Subcatchment2S: IMPERVIOUS Flow Length=280' Tc=2.6 min CN=97 Runoff=2.28 cfs 0.172 af Reach 3R: COMPOSITE Total Runoff Area = 2.420 ac Runoff Volume = 0.264 af Average Runoff Depth = 1.31' 87.60% Pervious = 2.120 ac 12.40% Impervious = 0.300 ac
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PRE DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 1S: POROUS
Runoff = 0.40 cfs @ 12.53 hrs, Volume= 0.092 af, Depth> 0.56" Routed to Reach 3R : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
1.080 30 Woods, Good, HSG A
0.110 39 >75% Grass cover, Good, HSG A
0.780 72 Dirt roads, HSG A
1.970 47 Weighted Average
1.970 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
2.5 140 0.0350 0.94 Shallow Concentrated Flow, Woodland Kv= 5.0 fps
1.6 190 0.0150 1.97 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps
19.1 430 Total
15.0 100 0.0450 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.42"
Subcatchment 1S: POROUS
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PRE DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 12
Summary for Subcatchment 2S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 2.28 cfs @ 12.10 hrs, Volume= 0.172 af, Depth> 4.59" Routed to Reach 3R : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.150 96 Gravel surface, HSG A
0.300 98 Paved parking, HSG A
0.450 97 Weighted Average
0.150 33.33% Pervious Area
0.300 66.67% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 180 0.0110 2.13 Shallow Concentrated Flow, Paved Kv= 20.3 fps
2.6 280 Total
1.2 100 0.0200 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
Subcatchment 2S: IMPERVIOUS
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PRE DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 13
Summary for Reach 3R: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.420 ac, 12.40% Impervious, Inflow Depth > 1.31" for 10 YEAR event Inflow = 2.32 cfs @ 12.10 hrs, Volume= 0.264 af Outflow = 2.32 cfs @ 12.10 hrs, Volume= 0.264 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 3R: COMPOSITE
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PRE DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 14
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S: POROUS Flow Length=430' Tc=19.1 min CN=47 Runoff=2.68 cfs 0.406 af Subcatchment2S: IMPERVIOUS Flow Length=280' Tc=2.6 min CN=97 Runoff=4.05 cfs 0.309 af Reach 3R: COMPOSITE
Subcatchment1S: POROUS Runoff Area=1.970 ac 0.00% Impervious Runoff Depth>2.47" Flow Length=430' Tc=19.1 min CN=47 Runoff=2.68 cfs 0.406 af Subcatchment2S: IMPERVIOUS Runoff Area=0.450 ac 66.67% Impervious Runoff Depth>8.24" Flow Length=280' Tc=2.6 min CN=97 Runoff=4.05 cfs 0.309 af Reach 3R: COMPOSITE Inflow=5.23 cfs 0.715 af Outflow=5.23 cfs 0.715 af Total Runoff Area = 2.420 ac Runoff Volume = 0.715 af Average Runoff Depth = 3.55" 87.60% Pervious = 2.120 ac 12.40% Impervious = 0.300 ac
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PRE DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 15
Summary for Subcatchment 1S: POROUS
Runoff = 2.68 cfs @ 12.35 hrs, Volume= 0.406 af, Depth> 2.47" Routed to Reach 3R : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
1.080 30 Woods, Good, HSG A
0.110 39 >75% Grass cover, Good, HSG A
0.780 72 Dirt roads, HSG A
1.970 47 Weighted Average
1.970 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
2.5 140 0.0350 0.94 Shallow Concentrated Flow, Woodland Kv= 5.0 fps
1.6 190 0.0150 1.97 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps
19.1 430 Total
15.0 100 0.0450 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.42"
Subcatchment 1S: POROUS
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PRE DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 16
Summary for Subcatchment 2S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 4.05 cfs @ 12.10 hrs, Volume= 0.309 af, Depth> 8.24" Routed to Reach 3R : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.150 96 Gravel surface, HSG A
0.300 98 Paved parking, HSG A
0.450 97 Weighted Average
0.150 33.33% Pervious Area
0.300 66.67% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 180 0.0110 2.13 Shallow Concentrated Flow, Paved Kv= 20.3 fps
2.6 280 Total
1.2 100 0.0200 1.42 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
Subcatchment 2S: IMPERVIOUS
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PRE DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 17
Summary for Reach 3R: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.420 ac, 12.40% Impervious, Inflow Depth > 3.55" for 100 YEAR event Inflow = 5.23 cfs @ 12.11 hrs, Volume= 0.715 af Outflow = 5.23 cfs @ 12.11 hrs, Volume= 0.715 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 3R: COMPOSITE
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APPENDIX B POST-DEVELOPED CONDITION CALCULATIONS
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Routing Diagram for POST DEV Prepared by Professional Design Services, Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
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POST DEV
Prepared by Professional Design Services Printed 12/31/2025
HydroCAD\circledR 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 2
Rainfall Events Listing
Event#Event NameStorm TypeCurveModeDuration (hours)B/BDepth (inches)AMC
12 YEARNOAA 24-hrDDefault24.0013.422
210 YEARNOAA 24-hrDDefault24.0015.382
325 yearNOAA 24-hrDDefault24.0016.682
4100 YEARNOAA 24-hrDDefault24.0019.482
Rainfall Events Listing
1 2 YEAR NOAA 24-hr D Default 24.00 1 3.42
2 10 YEAR NOAA 24-hr D Default 24.00 1 5.38
3 25 year NOAA 24-hr D Default 24.00 1 6.68
4 100 YEAR NOAA 24-hr D Default 24.00 1 9.48
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POST DEV Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Area Listing (all nodes)
Area (acres)CNDescription (subcatchment-numbers)
0.82039>75% Grass cover, Good, HSG A (1S, 6S, 10S)
0.79098Paved parking, HSG A (2S, 11S)
0.73098Roofs, HSG A (5S, 8S)
2.34077TOTAL AREA
Printed 12/31/2025 Page 3
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POST DEV Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Soil Listing (all nodes)
Area (acres)Soil GroupSubcatchment Numbers
2.340HSG A1S, 2S, 5S, 6S, 8S, 10S, 11S
0.000HSG B
0.000HSG C
0.000HSG D
0.000Other
2.340TOTAL AREA
Printed 12/31/2025 Page 4
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POST DEV
Prepared by Professional Design Services Printed 12/31/2025
HydroCAD\circledR 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 5
Ground Covers (all nodes)
HSG-A (acres)HSG-B (acres)HSG-C (acres)HSG-D (acres)Other (acres)Total (acres)Ground CoverSubcatchment Numbers
0.8200.0000.0000.0000.0000.820>75% Grass cover, Good1S, 6S, 10S
0.7900.0000.0000.0000.0000.790Paved parking2S, 11S
0.7300.0000.0000.0000.0000.730Roofs5S, 8S
2.3400.0000.0000.0000.0002.340TOTAL AREA
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 6
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS
Subcatchment1S: POROUS Runoff Area=0.570 ac 0.00% Impervious Runoff Depth>0.00" Flow Length=310' Tc=12.9 min CN=39 Runoff=0.00 cfs 0.000 af
Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>2.91"
Subcatchment2S: IMPERVIOUS
Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>2.91" Flow Length=310' Tc=13.1 min CN=98 Runoff=1.36 cfs 0.175 af
Subcatchment5S: IMPERVIOUS Runoff Area=0.270 ac 100.00% Impervious Runoff Depth>2.92" Flow Length=180' Slope=0.0100'/' Tc=1.6 min CN=98 Runoff=0.93 cfs 0.066 af
Subcatchment6S: POROUS
Subcatchment6S: POROUS Runoff Area=0.190 ac 0.00% Impervious Runoff Depth>0.00"
Flow Length=250' Tc=12.4 min CN=39 Runoff=0.00 cfs 0.000 af
Subcatchment8S: PROP WAREHOUSE Runoff Area=0.460 ac 100.00% Impervious Runoff Depth>2.92" Flow Length=280' Slope=0.0100'/' Tc=2.6 min CN=98 Runoff=1.48 cfs 0.112 af
Runoff Area=0.060 ac 0.00% Impervious Runoff Depth>0.00" Tc=2.0 min CN=39 Runoff=0.00 cfs 0.000 af
Subcatchment10S: BY-PASS POROUS
Runoff Area=0.070 ac 100.00% Impervious Runoff Depth>2.92" Tc=2.0 min CN=98 Runoff=0.24 cfs 0.017 af
Subcatchment11S: BY-PASS
Inflow=0.24 cfs 0.040 af
Outflow=0.24 cfs 0.040 af
Reach 10: COMPOSITE
Pond 3P: SSIB #1 SURFACE BASIN Peak Elevation=111.65' Storage=3,983 cfs Inflow=1.36 cfs 0.175 af Discarded=0.09 cfs 0.081 af Primary=0.19 cfs 0.023 af Outflow=0.28 cfs 0.104 af
Pond 8P: SSIB #2 UNDERGROUND Peak Elev=108.37' Storage=0.025 af Inflow=0.93 cfs 0.066 af
Discarded=0.09 cfs 0.065 af Primary=0.00 cfs 0.000 af Outflow=0.09 cfs 0.065 af
Pond 9P: SSIB #3 UNDERGROUND Peak Elev=111.92' Storage=0.047 af Inflow=1.48 cfs 0.112 af Discarded=0.12 cfs 0.102 af Primary=0.00 cfs 0.000 af Outflow=0.12 cfs 0.102 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.369 af Average Runoff Depth = 1.89" 35.04% Pervious = 0.820 ac 64.96% Impervious = 1.520 ac
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 1S: POROUS
[73] Warning: Peak may fall outside time span
Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.570 39 >75% Grass cover, Good, HSG A
0.570 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.3 50 0.0350 2.81
0.9 160 3.00 Direct Entry, PIPE FLOW
12.9 310 Total
Subcatchment 1S: POROUS
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2S: IMPERVIOUS
Runoff = 1.36 cfs @ 12.22 hrs, Volume= 0.175 af, Depth> 2.91" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.720 98 Paved parking, HSG A
0.720 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.5 50 0.0110 1.57
0.9 160 3.00 Direct Entry, PIPE FLOW
13.1 310 Total
Subcatchment 2S: IMPERVIOUS
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 5S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.93 cfs @ 12.08 hrs, Volume= 0.066 af, Depth> 2.92" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.270 98 Roofs, HSG A
0.270 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 50 0.0100 0.94 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.7 130 3.00 Direct Entry, PIPE FLOW
1.6 180 Total
Subcatchment 5S: IMPERVIOUS
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment 6S: POROUS
[73] Warning: Peak may fall outside time span
Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.190 39 >75% Grass cover, Good, HSG A
0.190 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.3 90 0.0270 0.13 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Paved Kv= 20.3 fps
1.1 160 0.0150 2.49
12.4 250 Total
Subcatchment 6S: POROUS
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 8S: PROP WAREHOUSE BLDG
[49] Hint: Tc<2dt may require smaller dt
Runoff = 1.48 cfs @ 12.10 hrs, Volume= 0.112 af, Depth> 2.92" Routed to Pond 9P : SSIB #3 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.460 98 Roofs, HSG A
0.460 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.5 100 0.0100 1.08 Sheet Flow,
0.3 40 0.0100 2.03 Smooth surfaces n= 0.011 P2= 3.42"
0.8 140 3.00 Shallow Concentrated Flow, Paved Kv= 20.3 fps
Direct Entry, PIPE FLOW
2.6 280 Total
Subcatchment 8S: PROP WAREHOUSE BLDG
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 12
Summary for Subcatchment 10S: BY-PASS POROUS
[49] Hint: Tc<2dt may require smaller dt
[73] Warning: Peak may fall outside time span
Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac)CNDescription
0.06039>75% Grass cover, Good, HSG A
0.060100.00% Pervious Area
Tc (min)Length (feet)Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.0Direct Entry,
Subcatchment 10S: BY-PASS POROUS
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 11S: BY-PASS IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.24 cfs @ 12.09 hrs, Volume= 0.017 af, Depth> 2.92" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.070 98 Paved parking, HSG A
0.070 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
Direct Entry,
Subcatchment 11S: BY-PASS IMPERVIOUS
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POST DEV NOAA Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
NOAA 24-hr D 2 YEAR Rainfall=3.42" Printed 12/31/2025
2 YEAR Rainfall=3.42" Printed 12/31/2025 Page 14
Summary for Reach 10: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.340 ac, 64.96% Impervious, Inflow Depth > 0.21" for 2 YEAR event Inflow = 0.24 cfs @ 12.09 hrs, Volume= 0.040 af Outflow = 0.24 cfs @ 12.09 hrs, Volume= 0.040 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 10: COMPOSITE
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 15
Summary for Pond 3P: SSIB #1 SURFACE BASIN
[82] Warning: Early inflow requires earlier time span
Inflow Area = 1.290 ac, 55.81% Impervious, Inflow Depth > 1.63" for 2 YEAR event Inflow = 1.36 cfs @ 12.22 hrs, Volume= 0.175 af Outflow = 0.28 cfs @ 13.18 hrs, Volume= 0.104 af, Atten= 79%, Lag= 57.6 min Discarded = 0.09 cfs @ 13.18 hrs, Volume= 0.081 af Primary = 0.19 cfs @ 13.18 hrs, Volume= 0.023 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 111.65' @ 13.18 hrs Surf.Area= 2,939 sf Storage= 3,983 cf Plug-Flow detention time= 167.6 min calculated for 0.104 af (59% of inflow) Center-of-Mass det. time= 81.6 min ( 831.1 - 749.5 )
VolumeInvertAvail.StorageStorage Description
#1110.00'12,950 cfCustom Stage Data (Prismatic)Listed below (Recalc)
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
110.002,00000
111.002,4502,2252,225
112.003,2002,8255,050
113.004,0003,6008,650
114.004,6004,30012,950
DeviceRoutingInvertOutlet Devices
#1Discarded110.00'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 106.00'
#2Primary111.50'12.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
#3Primary113.00'24.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.09 cfs @ 13.18 hrs HW=111.65' (Free Discharge) 1=Exfiltration (Controls 0.09 cfs)
Primary OutFlow Max=0.19 cfs @ 13.18 hrs HW=111.65' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.19 cfs @ 1.25 fps) 3=Orifice/Grate (Controls 0.00 cfs)
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 16
Pond 3P: SSIB #1 SURFACE BASIN
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 17
Stage-Discharge for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.000.000.000.00112.651.720.131.59
110.050.050.050.00112.701.760.131.63
110.100.050.050.00112.751.800.131.67
110.150.050.050.00112.801.840.131.71
110.200.050.050.00112.851.880.131.74
110.250.050.050.00112.901.920.141.78
110.300.050.050.00112.951.950.141.82
110.350.050.050.00113.001.990.141.85
110.400.060.060.00113.052.470.142.33
110.450.060.060.00113.103.300.143.16
110.500.060.060.00113.154.380.144.23
110.550.060.060.00113.205.640.155.50
110.600.060.060.00113.257.070.156.92
110.650.060.060.00113.308.650.158.50
110.700.060.060.00113.3510.360.1510.21
110.750.060.060.00113.4012.190.1512.04
110.800.060.060.00113.4514.140.1513.99
110.850.070.070.00113.5016.200.1616.05
110.900.070.070.00113.5518.370.1618.21
110.950.070.070.00113.6020.630.1620.47
111.000.070.070.00113.6522.980.1622.82
111.050.070.070.00113.7025.430.1625.27
111.100.070.070.00113.7527.970.1727.80
111.150.070.070.00113.8030.590.1730.42
111.200.080.080.00113.8533.290.1733.12
111.250.080.080.00113.9036.070.1735.90
111.300.080.080.00113.9538.930.1738.76
111.350.080.080.00114.0041.140.1740.97
111.400.080.080.00
111.450.080.080.00
111.500.090.090.00
111.550.120.090.04
111.600.190.090.10
111.650.280.090.19
111.700.380.090.29
111.750.500.090.40
111.800.620.100.53
111.850.750.100.66
111.900.860.100.76
111.950.940.100.84
112.001.020.100.92
112.051.090.100.99
112.101.160.111.05
112.151.220.111.11
112.201.280.111.17
112.251.330.111.22
112.301.390.111.27
112.351.440.111.32
112.401.490.121.37
112.451.540.121.42
112.501.580.121.46
112.551.630.121.51
112.601.670.121.55
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 18
Stage-Area-Storage for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
110.002,0000
110.052,022101
110.102,045202
110.152,068305
110.202,090409
110.252,113514
110.302,135620
110.352,157728
110.402,180836
110.452,203946
110.502,2251,056
110.552,2471,168
110.602,2701,281
110.652,2931,395
110.702,3151,510
110.752,3381,627
110.802,3601,744
110.852,3821,863
110.902,4051,982
110.952,4282,103
111.002,4502,225
111.052,4872,348
111.102,5252,474
111.152,5632,601
111.202,6002,730
111.252,6382,861
111.302,6752,994
111.352,7123,128
111.402,7503,265
111.452,7883,403
111.502,8253,544
111.552,8623,686
111.602,9003,830
111.652,9383,976
111.702,9754,124
111.753,0134,273
111.803,0504,425
111.853,0874,578
111.903,1254,734
111.953,1634,891
112.003,2005,050
112.053,2405,211
112.103,2805,374
112.153,3205,539
112.203,3605,706
112.253,4005,875
112.303,4406,046
112.353,4806,219
112.403,5206,394
112.453,5606,571
112.503,6006,750
112.553,6406,931
112.603,6807,114
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
112.653,7207,299
112.703,7607,486
112.753,8007,675
112.803,8407,866
112.853,8808,059
112.903,9208,254
112.953,9608,451
113.004,0008,650
113.054,0308,851
113.104,0609,053
113.154,0909,257
113.204,1209,462
113.254,1509,669
113.304,1809,877
113.354,21010,087
113.404,24010,298
113.454,27010,511
113.504,30010,725
113.554,33010,941
113.604,36011,158
113.654,39011,377
113.704,42011,597
113.754,45011,819
113.804,48012,042
113.854,51012,267
113.904,54012,493
113.954,57012,721
114.004,60012,950
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 19
Summary for Pond 8P: SSIB #2 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 1.71" for 2 YEAR event Inflow = 0.93 cfs @ 12.08 hrs, Volume= 0.066 af Outflow = 0.09 cfs @ 12.99 hrs, Volume= 0.065 af, Atten= 91%, Lag= 54.4 min Discarded = 0.09 cfs @ 12.99 hrs, Volume= 0.065 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 10: COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 108.37' @ 12.99 hrs Surf.Area= 0.064 ac Storage= 0.025 af Plug-Flow detention time= 100.6 min calculated for 0.065 af (99% of inflow) Center-of-Mass det. time= 98.8 min (834.8 - 736.1)
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95"W x 66.33"L x 3.00"H Field A
0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside = 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside = 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 afTotal Available Storage
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.09 cfs @ 12.99 hrsHW=108.37' (Free Discharge)
1=Exfiltration ( Controls 0.09 cfs)
Primary OutFlowMax=0.00 cfs @ 5.00 hrsHW=107.50' (Free Discharge)
2=Orifice/Grate ( Controls 0.00 cfs)
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 20
Pond 8P: SSIB #2 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 12 Rows x 28.0" Wide + 13.4" Spacing x 11 + 10.0" Side Stone x 2 = 41.95' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 36 Chambers x 62.0 cf + 40.28' Header x 3.10 sf x 2 = 2,481.8 cf Chamber Storage 36 Chambers x 78.4 cf + 40.28' Header x 3.92 sf x 2 = 3,137.9 cf Displacement 8,348.3 cf Field - 3,137.9 cf Chambers = 5,210.4 cf Stone x 40.0% Voids = 2,084.2 cf Stone Storage Chamber Storage + Stone Storage = 4,565.9 cf = 0.105 af Overall Storage Efficiency = 54.7% Overall System Size = 66.33' x 41.95' x 3.00'
36 Chambers 309.2 cy Field 193.0 cy Stone
0101010101010101010
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 21
Pond 8P: SSIB #2 UNDERGROUND
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 22
Stage-Discharge for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
107.500.000.000.00
107.550.070.070.00
107.600.070.070.00
107.650.070.070.00
107.700.070.070.00
107.750.070.070.00
107.800.070.070.00
107.850.070.070.00
107.900.070.070.00
107.950.080.080.00
108.000.080.080.00
108.050.080.080.00
108.100.080.080.00
108.150.080.080.00
108.200.080.080.00
108.250.080.080.00
108.300.090.090.00
108.350.090.090.00
108.400.090.090.00
108.450.090.090.00
108.500.090.090.00
108.550.090.090.00
108.600.090.090.00
108.650.090.090.00
108.700.100.100.00
108.750.100.100.00
108.800.100.100.00
108.850.100.100.00
108.900.100.100.00
108.950.100.100.00
109.000.100.100.00
109.050.130.100.02
109.100.170.110.07
109.150.230.110.12
109.200.300.110.19
109.250.380.110.27
109.300.460.110.35
109.350.550.110.44
109.400.620.110.50
109.450.680.110.56
109.500.730.120.61
109.550.770.120.66
109.600.820.120.70
109.650.860.120.74
109.700.900.120.78
109.750.940.120.81
109.800.970.120.85
109.851.010.120.88
109.901.040.130.91
109.951.070.130.95
110.001.100.130.98
110.051.130.131.00
110.101.160.131.03
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.151.190.131.06
110.201.220.131.09
110.251.250.141.11
110.301.270.141.14
110.351.300.141.16
110.401.330.141.19
110.451.350.141.21
110.501.380.141.23
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 23
Stage-Area-Storage for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
107.500.0640.000
107.550.0640.001
107.600.0640.003
107.650.0640.004
107.700.0640.005
107.750.0640.006
107.800.0640.008
107.850.0640.009
107.900.0640.010
107.950.0640.011
108.000.0640.012
108.050.0640.013
108.100.0640.014
108.150.0640.016
108.200.0640.018
108.250.0640.020
108.300.0640.022
108.350.0640.024
108.400.0640.026
108.450.0640.028
108.500.0640.030
108.550.0640.032
108.600.0640.034
108.650.0640.036
108.700.0640.039
108.750.0640.041
108.800.0640.043
108.850.0640.045
108.900.0640.048
108.950.0640.050
109.000.0640.052
109.050.0640.055
109.100.0640.057
109.150.0640.059
109.200.0640.062
109.250.0640.064
109.300.0640.066
109.350.0640.068
109.400.0640.071
109.450.0640.073
109.500.0640.075
109.550.0640.077
109.600.0640.079
109.650.0640.081
109.700.0640.083
109.750.0640.085
109.800.0640.087
109.850.0640.089
109.900.0640.090
109.950.0640.092
110.000.0640.093
110.050.0640.094
110.100.0640.095
Elevation (feet)Surface (acres)Storage (acre-feet)
110.150.0640.096
110.200.0640.097
110.250.0640.098
110.300.0640.100
110.350.0640.101
110.400.0640.102
110.450.0640.104
110.500.0640.105
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 24
Summary for Pond 9P: SSIB #3 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 100.00% Impervious, Inflow Depth > 2.92" for 2 YEAR event Inflow = 1.48 cfs @ 12.10 hrs, Volume= 0.112 af Outflow = 0.12 cfs @ 13.25 hrs, Volume= 0.102 af, Atten= 92%, Lag= 69.2 min Discarded = 0.12 cfs @ 13.25 hrs, Volume= 0.102 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 10: COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 111.92' @ 13.25 hrs Surf.Area= 0.085 ac Storage= 0.047 af Plug-Flow detention time= 144.1 min calculated for 0.101 af (91% of inflow) Center-of-Mass det. time= 111.3 min (848.5 - 737.2)
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A
0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 Inside #1 Inside = 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside = 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 afTotal Available Storage
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.12 cfs @ 13.25 hrs HW=111.92' (Free Discharge)
1=Exfiltration ( Controls 0.12 cfs)
Primary OutFlowMax=0.00 cfs @ 5.00 hrs HW=110.80' (Free Discharge)
2=Orifice/Grate ( Controls 0.00 cfs)
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NOAA 24-hr D 2 YEAR Rainfall=3.42" Printed 12/31/2025 Page 25
POST DEV NOAA Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Pond 9P: SSIB #3 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 16 Rows x 28.0" Wide + 13.4" Spacing x 15 + 10.0" Side Stone x 2 = 55.75' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 48 Chambers x 62.0 cf + 54.08' Header x 3.10 sf x 2 = 3,311.3 cf Chamber Storage 48 Chambers x 78.4 cf + 54.08' Header x 3.92 sf x 2 = 4,186.8 cf Displacement 11,094.6 cf Field - 4,186.8 cf Chambers = 6,907.8 cf Stone x 40.0% Voids = 2,763.1 cf Stone Storage Chamber Storage + Stone Storage = 6,074.4 cf = 0.139 af Overall Storage Efficiency = 54.8% Overall System Size = 66.33' x 55.75' x 3.00'
48 Chambers 410.9 cy Field 255.8 cy Stone
101010
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 26
Pond 9P: SSIB #3 UNDERGROUND
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 27
Stage-Discharge for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.800.000.000.00
110.850.090.090.00
110.900.090.090.00
110.950.090.090.00
111.000.090.090.00
111.050.090.090.00
111.100.090.090.00
111.150.100.100.00
111.200.100.100.00
111.250.100.100.00
111.300.100.100.00
111.350.100.100.00
111.400.100.100.00
111.450.110.110.00
111.500.110.110.00
111.550.110.110.00
111.600.110.110.00
111.650.110.110.00
111.700.110.110.00
111.750.110.110.00
111.800.120.120.00
111.850.120.120.00
111.900.120.120.00
111.950.120.120.00
112.000.120.120.00
112.050.120.120.00
112.100.130.130.00
112.150.130.130.00
112.200.130.130.00
112.250.130.130.00
112.300.130.130.00
112.350.130.130.00
112.400.130.130.00
112.450.140.140.00
112.500.140.140.00
112.550.140.140.00
112.600.140.140.00
112.650.140.140.00
112.700.140.140.00
112.750.150.150.00
112.800.150.150.00
112.850.150.150.00
112.900.150.150.00
112.950.150.150.00
113.000.150.150.00
113.050.190.150.04
113.100.260.160.10
113.150.340.160.19
113.200.450.160.29
113.250.560.160.40
113.300.690.160.53
113.350.830.160.66
113.400.980.170.81
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
113.451.140.170.97
113.501.300.171.13
113.551.440.171.27
113.601.560.171.39
113.651.670.171.50
113.701.770.171.59
113.751.860.181.68
113.801.950.181.77
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POST DEV NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 28
Stage-Area-Storage for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
110.800.0850.000
110.850.0850.002
110.900.0850.003
110.950.0850.005
111.000.0850.007
111.050.0850.008
111.100.0850.010
111.150.0850.012
111.200.0850.013
111.250.0850.015
111.300.0850.016
111.350.0850.017
111.400.0850.019
111.450.0850.021
111.500.0850.024
111.550.0850.026
111.600.0850.029
111.650.0850.031
111.700.0850.034
111.750.0850.037
111.800.0850.040
111.850.0850.042
111.900.0850.045
111.950.0850.048
112.000.0850.051
112.050.0850.054
112.100.0850.057
112.150.0850.060
112.200.0850.064
112.250.0850.067
112.300.0850.070
112.350.0850.073
112.400.0850.076
112.450.0850.079
112.500.0850.082
112.550.0850.085
112.600.0850.088
112.650.0850.091
112.700.0850.094
112.750.0850.097
112.800.0850.100
112.850.0850.103
112.900.0850.105
112.950.0850.108
113.000.0850.111
113.050.0850.113
113.100.0850.116
113.150.0850.118
113.200.0850.120
113.250.0850.122
113.300.0850.124
113.350.0850.125
113.400.0850.126
Elevation (feet)Surface (acres)Storage (acre-feet)
113.450.0850.128
113.500.0850.129
113.550.0850.131
113.600.0850.133
113.650.0850.134
113.700.0850.136
113.750.0850.138
113.800.0850.139
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 29
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS
Subcatchment1S: POROUS Runoff Area=0.570 ac 0.00% Impervious Runoff Depth>0.21" Flow Length=310' Tc=12.9 min CN=39 Runoff=0.03 cfs 0.010 af
Subcatchment2S: IMPERVIOUS
Subcatchment2S: IMPERVIOUS Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>4.66" Flow Length=310' Tc=13.1 min CN=98 Runoff=2.16 cfs 0.280 af
Subcatchment5S: IMPERVIOUS Runoff Area=0.270 ac 100.00% Impervious Runoff Depth>4.66" Flow Length=180' Slope=0.0100'/' Tc=1.6 min CN=98 Runoff=1.48 cfs 0.105 af
Runoff Area=0.190 ac 0.00% Impervious Runoff Depth>0.22" Flow Length=250' Tc=12.4 min CN=39 Runoff=0.01 cfs 0.003 af
Subcatchment6S: POROUS
Subcatchment8S: PROP WAREHOUSE Runoff Area=0.460 ac 100.00% Impervious Runoff Depth>4.66" Flow Length=280' Slope=0.0100'/' Tc=2.6 min CN=98 Runoff=2.35 cfs 0.179 af
Subcatchment10S: BY-PASSPOROUS Runoff Area=0.060 ac 0.00% Impervious Runoff Depth>0.22" Tc=2.0 min CN=39 Runoff=0.00 cfs 0.001 af
Runoff Area=0.070 ac 100.00% Impervious Runoff Depth>4.66" Tc=2.0 min CN=98 Runoff=0.37 cfs 0.027 af
Subcatchment11S: BY-PASS
Inflow=1.00 cfs 0.149 af Outflow=1.00 cfs 0.149 af
Reach 10: COMPOSITE
Pond 3P: SSIB #1 SURFACE BASIN Peak Elev= $ 112.02' $ Storage=5,118 cf Inflow= $ 2.16 $ cfs 0.290 af Discarded=0.10 cfs 0.089 af Primary=0.95 cfs 0.120 af Outflow=1.05 cfs 0.209 af
Pond 8P: SSIB #2 UNDERGROUND Peak Elev=108.89' Storage=0.047 af Inflow=1.48 cfs 0.108 af
Discarded=0.10 cfs 0.088 af Primary=0.00 cfs 0.000 af Outflow=0.10 cfs 0.088 af
Pond 9P: SSIB #3 UNDERGROUND Peak Elev=112.59' Storage=0.087 af Inflow=2.35 cfs 0.179 af Discarded=0.14 cfs 0.127 af Primary=0.00 cfs 0.000 af Outflow=0.14 cfs 0.127 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.605 af Average Runoff Depth = 3.10" 35.04% Pervious = 0.820 ac 64.96% Impervious = 1.520 ac
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 30
Summary for Subcatchment 1S: POROUS
Runoff = 0.03 cfs @ 13.03 hrs, Volume= 0.010 af, Depth> 0.21" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.570 39 >75% Grass cover, Good, HSG A
0.570 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42"
0.3 50 0.0350 2.81 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.9 160 3.00 Direct Entry, PIPE FLOW
12.9 310 Total
Subcatchment 1S: POROUS
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 31
Summary for Subcatchment 2S: IMPERVIOUS
Runoff = 2.16 cfs @ 12.22 hrs, Volume=
Runoff = 2.16 cfs @ 12.22 hrs, Volume= Routed to Pond 3P : SSIB #1 SURFACE BASIN 0.280 af, Depth> 4.66"
0.280 af, Depth> 4.66"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.720 98 Paved parking, HSG A
0.720 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.5 50 0.0110 1.57
0.9 160 3.00 Direct Entry, PIPE FLOW
13.1 310 Total
Subcatchment 2S: IMPERVIOUS
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 32
Summary for Subcatchment 5S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 1.48 cfs @ 12.08 hrs, Volume= 0.105 af, Depth> 4.66" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.270 98 Roofs, HSG A
0.270 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 50 0.0100 0.94 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.7 130 3.00 Direct Entry, PIPE FLOW
1.6 180 Total
Subcatchment 5S: IMPERVIOUS
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 33
Summary for Subcatchment 6S: POROUS
Runoff = 0.01 cfs @ 13.01 hrs, Volume= 0.003 af, Depth> 0.22" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.190 39 >75% Grass cover, Good, HSG A
0.190 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.3 90 0.0270 0.13 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42"
1.1 160 0.0150 2.49 Shallow Concentrated Flow, Paved Kv= 20.3 fps
12.4 250 Total
Subcatchment 6S: POROUS
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 34
Summary for Subcatchment 8S: PROP WAREHOUSE BLDG
[49] Hint: Tc<2dt may require smaller dt
Runoff = 2.35 cfs @ 12.10 hrs, Volume= 0.179 af, Depth> 4.66" Routed to Pond 9P : SSIB #3 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.460 98 Roofs, HSG A
0.460 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.5 100 0.0100 1.08 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.3 40 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fps
0.8 140 3.00 Direct Entry, PIPE FLOW
2.6 280 Total
Subcatchment 8S: PROP WAREHOUSE BLDG
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 35
Summary for Subcatchment 10S: BY-PASS POROUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.00 cfs @ 12.50 hrs, Volume= 0.001 af, Depth> 0.22" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac)CNDescription
0.06039>75% Grass cover, Good, HSG A
0.060100.00% Pervious Area
Tc (min)Length (feet)Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.0Direct Entry,
Subcatchment 10S: BY-PASS POROUS
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 36
Summary for Subcatchment 11S: BY-PASS IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.37 cfs @ 12.09 hrs, Volume= 0.027 af, Depth> 4.66" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.070 98 Paved parking, HSG A
0.070 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
Direct Entry,
Subcatchment 11S: BY-PASS IMPERVIOUS
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 37
Summary for Reach 10: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.340 ac, 64.96% Impervious, Inflow Depth > 0.76" for 10 YEAR event Inflow = 1.00 cfs @ 12.65 hrs, Volume= 0.149 af Outflow = 1.00 cfs @ 12.65 hrs, Volume= 0.149 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 10: COMPOSITE
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 38
Summary for Pond 3P: SSIB #1 SURFACE BASIN
[82] Warning: Early inflow requires earlier time span
Inflow Area =1.290 ac, 55.81% Impervious, Inflow Depth > 2.70" for 10 YEAR event
Inflow =2.16 cfs @ 12.22 hrs, Volume= 0.290 af
Outflow =1.05 cfs @ 12.67 hrs, Volume= 0.209 af, Atten= 51%, Lag= 26.5 min
Discarded =0.10 cfs @ 12.67 hrs, Volume= 0.089 af
Primary =0.95 cfs @ 12.67 hrs, Volume= 0.120 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 112.02' @ 12.67 hrs Surf.Area= 3,217 sf Storage= 5,118 cf
Plug-Flow detention time = 129.4 min calculated for 0.208 af (72% of inflow) Center-of-Mass det. time = 59.2 min (812.0 - 752.7)
VolumeInvertAvail.StorageStorage Description
#1110.00'12,950 cfCustom Stage Data (Prismatic)Listed below (Recalc)
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
110.002,00000
111.002,4502,2252,225
112.003,2002,8255,050
113.004,0003,6008,650
114.004,6004,30012,950
DeviceRoutingInvertOutlet Devices
#1Discarded110.00'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 106.00'
#2Primary111.50'12.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
#3Primary113.00'24.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.10 cfs @ 12.67 hrs HW=112.02' (Free Discharge) 1=Exfiltration (Controls 0.10 cfs)
Primary OutFlow Max=0.95 cfs @ 12.67 hrs HW=112.02' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.95 cfs @ 2.84 fps) 3=Orifice/Grate (Controls 0.00 cfs)
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 39
Pond 3P: SSIB #1 SURFACE BASIN
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 40
Stage-Discharge for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.000.000.000.00112.651.720.131.59
110.050.050.050.00112.701.760.131.63
110.100.050.050.00112.751.800.131.67
110.150.050.050.00112.801.840.131.71
110.200.050.050.00112.851.880.131.74
110.250.050.050.00112.901.920.141.78
110.300.050.050.00112.951.950.141.82
110.350.050.050.00113.001.990.141.85
110.400.060.060.00113.052.470.142.33
110.450.060.060.00113.103.300.143.16
110.500.060.060.00113.154.380.144.23
110.550.060.060.00113.205.640.155.50
110.600.060.060.00113.257.070.156.92
110.650.060.060.00113.308.650.158.50
110.700.060.060.00113.3510.360.1510.21
110.750.060.060.00113.4012.190.1512.04
110.800.060.060.00113.4514.140.1513.99
110.850.070.070.00113.5016.200.1616.05
110.900.070.070.00113.5518.370.1618.21
110.950.070.070.00113.6020.630.1620.47
111.000.070.070.00113.6522.980.1622.82
111.050.070.070.00113.7025.430.1625.27
111.100.070.070.00113.7527.970.1727.80
111.150.070.070.00113.8030.590.1730.42
111.200.080.080.00113.8533.290.1733.12
111.250.080.080.00113.9036.070.1735.90
111.300.080.080.00113.9538.930.1738.76
111.350.080.080.00114.0041.140.1740.97
111.400.080.080.00
111.450.080.080.00
111.500.090.090.00
111.550.120.090.04
111.600.190.090.10
111.650.280.090.19
111.700.380.090.29
111.750.500.090.40
111.800.620.100.53
111.850.750.100.66
111.900.860.100.76
111.950.940.100.84
112.001.020.100.92
112.051.090.100.99
112.101.160.111.05
112.151.220.111.11
112.201.280.111.17
112.251.330.111.22
112.301.390.111.27
112.351.440.111.32
112.401.490.121.37
112.451.540.121.42
112.501.580.121.46
112.551.630.121.51
112.601.670.121.55
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 41
Stage-Area-Storage for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
110.002,0000
110.052,022101
110.102,045202
110.152,068305
110.202,090409
110.252,113514
110.302,135620
110.352,157728
110.402,180836
110.452,203946
110.502,2251,056
110.552,2471,168
110.602,2701,281
110.652,2931,395
110.702,3151,510
110.752,3381,627
110.802,3601,744
110.852,3821,863
110.902,4051,982
110.952,4282,103
111.002,4502,225
111.052,4872,348
111.102,5252,474
111.152,5632,601
111.202,6002,730
111.252,6382,861
111.302,6752,994
111.352,7123,128
111.402,7503,265
111.452,7883,403
111.502,8253,544
111.552,8623,686
111.602,9003,830
111.652,9383,976
111.702,9754,124
111.753,0134,273
111.803,0504,425
111.853,0874,578
111.903,1254,734
111.953,1634,891
112.003,2005,050
112.053,2405,211
112.103,2805,374
112.153,3205,539
112.203,3605,706
112.253,4005,875
112.303,4406,046
112.353,4806,219
112.403,5206,394
112.453,5606,571
112.503,6006,750
112.553,6406,931
112.603,6807,114
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
112.653,7207,299
112.703,7607,486
112.753,8007,675
112.803,8407,866
112.853,8808,059
112.903,9208,254
112.953,9608,451
113.004,0008,650
113.054,0308,851
113.104,0609,053
113.154,0909,257
113.204,1209,462
113.254,1509,669
113.304,1809,877
113.354,21010,087
113.404,24010,298
113.454,27010,511
113.504,30010,725
113.554,33010,941
113.604,36011,158
113.654,39011,377
113.704,42011,597
113.754,45011,819
113.804,48012,042
113.854,51012,267
113.904,54012,493
113.954,57012,721
114.004,60012,950
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 42
Summary for Pond 8P: SSIB #2 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 2.83" for 10 YEAR event Inflow = 1.48 cfs @ 12.08 hrs, Volume= 0.108 af Outflow = 0.10 cfs @ 13.45 hrs, Volume= 0.088 af, Atten= 93%, Lag= 82.1 min Discarded = 0.10 cfs @ 13.45 hrs, Volume= 0.088 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 10: COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 108.89' @ 13.45 hrs Surf.Area= 0.064 ac Storage= 0.047 af Plug-Flow detention time= 160.2 min calculated for 0.088 af (81% of inflow) Center-of-Mass det. time= 102.6 min (841.8 - 739.2)
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95"W x 66.33"L x 3.00"H Field A
0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 afTotal Available Storage
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.10 cfs @ 13.45 hrs HW=108.89' (Free Discharge)
1=Exfiltration ( Controls 0.10 cfs)
Primary OutFlowMax=0.00 cfs @ 5.00 hrs HW=107.50' (Free Discharge)
2=Orifice/Grate ( Controls 0.00 cfs)
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 43
Pond 8P: SSIB #2 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 12 Rows x 28.0" Wide + 13.4" Spacing x 11 + 10.0" Side Stone x 2 = 41.95' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 36 Chambers x 62.0 cf + 40.28' Header x 3.10 sf x 2 = 2,481.8 cf Chamber Storage 36 Chambers x 78.4 cf + 40.28' Header x 3.92 sf x 2 = 3,137.9 cf Displacement 8,348.3 cf Field - 3,137.9 cf Chambers = 5,210.4 cf Stone x 40.0% Voids = 2,084.2 cf Stone Storage Chamber Storage + Stone Storage = 4,565.9 cf = 0.105 af Overall Storage Efficiency = 54.7% Overall System Size = 66.33' x 41.95' x 3.00'
36 Chambers 309.2 cy Field 193.0 cy Stone
010101
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 44
Pond 8P: SSIB #2 UNDERGROUND
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 45
Stage-Discharge for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
107.500.000.000.00
107.550.070.070.00
107.600.070.070.00
107.650.070.070.00
107.700.070.070.00
107.750.070.070.00
107.800.070.070.00
107.850.070.070.00
107.900.070.070.00
107.950.080.080.00
108.000.080.080.00
108.050.080.080.00
108.100.080.080.00
108.150.080.080.00
108.200.080.080.00
108.250.080.080.00
108.300.090.090.00
108.350.090.090.00
108.400.090.090.00
108.450.090.090.00
108.500.090.090.00
108.550.090.090.00
108.600.090.090.00
108.650.090.090.00
108.700.100.100.00
108.750.100.100.00
108.800.100.100.00
108.850.100.100.00
108.900.100.100.00
108.950.100.100.00
109.000.100.100.00
109.050.130.100.02
109.100.170.110.07
109.150.230.110.12
109.200.300.110.19
109.250.380.110.27
109.300.460.110.35
109.350.550.110.44
109.400.620.110.50
109.450.680.110.56
109.500.730.120.61
109.550.770.120.66
109.600.820.120.70
109.650.860.120.74
109.700.900.120.78
109.750.940.120.81
109.800.970.120.85
109.851.010.120.88
109.901.040.130.91
109.951.070.130.95
110.001.100.130.98
110.051.130.131.00
110.101.160.131.03
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.151.190.131.06
110.201.220.131.09
110.251.250.141.11
110.301.270.141.14
110.351.300.141.16
110.401.330.141.19
110.451.350.141.21
110.501.380.141.23
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 46
Stage-Area-Storage for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
107.500.0640.000
107.550.0640.001
107.600.0640.003
107.650.0640.004
107.700.0640.005
107.750.0640.006
107.800.0640.008
107.850.0640.009
107.900.0640.010
107.950.0640.011
108.000.0640.012
108.050.0640.013
108.100.0640.014
108.150.0640.016
108.200.0640.018
108.250.0640.020
108.300.0640.022
108.350.0640.024
108.400.0640.026
108.450.0640.028
108.500.0640.030
108.550.0640.032
108.600.0640.034
108.650.0640.036
108.700.0640.039
108.750.0640.041
108.800.0640.043
108.850.0640.045
108.900.0640.048
108.950.0640.050
109.000.0640.052
109.050.0640.055
109.100.0640.057
109.150.0640.059
109.200.0640.062
109.250.0640.064
109.300.0640.066
109.350.0640.068
109.400.0640.071
109.450.0640.073
109.500.0640.075
109.550.0640.077
109.600.0640.079
109.650.0640.081
109.700.0640.083
109.750.0640.085
109.800.0640.087
109.850.0640.089
109.900.0640.090
109.950.0640.092
110.000.0640.093
110.050.0640.094
110.100.0640.095
Elevation (feet)Surface (acres)Storage (acre-feet)
110.150.0640.096
110.200.0640.097
110.250.0640.098
110.300.0640.100
110.350.0640.101
110.400.0640.102
110.450.0640.104
110.500.0640.105
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 47
Summary for Pond 9P: SSIB #3 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac,100.00% Impervious, Inflow Depth > 4.66" for 10 YEAR event Inflow = 2.35 cfs @ 12.10 hrs, Volume= 0.179 af Outflow = 0.14 cfs @ 13.59 hrs, Volume= 0.127 af, Atten= 94%, Lag= 89.8 min Discarded = 0.14 cfs @ 13.59 hrs, Volume= 0.127 af Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 112.59' @ 13.59 hrs Surf.Area= 0.085 ac Storage= 0.087 af Plug-Flow detention time= 170.1 min calculated for 0.127 af (71% of inflow) Center-of-Mass det. time= 99.5 min ( 833.8 - 734.2 )
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A
0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 Inside #1 Inside = 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside = 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 afTotal Available Storage
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.14 cfs @ 13.59 hrs HW=112.59' (Free Discharge)
1=Exfiltration ( Controls 0.14 cfs)
Primary OutFlowMax=0.00 cfs @ 5.00 hrs HW=110.80' (Free Discharge)
2=Orifice/Grate ( Controls 0.00 cfs)
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 48
Pond 9P: SSIB #3 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 16 Rows x 28.0" Wide + 13.4" Spacing x 15 + 10.0" Side Stone x 2 = 55.75' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 48 Chambers x 62.0 cf + 54.08' Header x 3.10 sf x 2 = 3,311.3 cf Chamber Storage 48 Chambers x 78.4 cf + 54.08' Header x 3.92 sf x 2 = 4,186.8 cf Displacement 11,094.6 cf Field - 4,186.8 cf Chambers = 6,907.8 cf Stone x 40.0% Voids = 2,763.1 cf Stone Storage Chamber Storage + Stone Storage = 6,074.4 cf = 0.139 af Overall Storage Efficiency = 54.8% Overall System Size = 66.33' x 55.75' x 3.00'
48 Chambers 410.9 cy Field 255.8 cy Stone
101010
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 49
Pond 9P: SSIB #3 UNDERGROUND
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 50
Stage-Discharge for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.800.000.000.00
110.850.090.090.00
110.900.090.090.00
110.950.090.090.00
111.000.090.090.00
111.050.090.090.00
111.100.090.090.00
111.150.100.100.00
111.200.100.100.00
111.250.100.100.00
111.300.100.100.00
111.350.100.100.00
111.400.100.100.00
111.450.110.110.00
111.500.110.110.00
111.550.110.110.00
111.600.110.110.00
111.650.110.110.00
111.700.110.110.00
111.750.110.110.00
111.800.120.120.00
111.850.120.120.00
111.900.120.120.00
111.950.120.120.00
112.000.120.120.00
112.050.120.120.00
112.100.130.130.00
112.150.130.130.00
112.200.130.130.00
112.250.130.130.00
112.300.130.130.00
112.350.130.130.00
112.400.130.130.00
112.450.140.140.00
112.500.140.140.00
112.550.140.140.00
112.600.140.140.00
112.650.140.140.00
112.700.140.140.00
112.750.150.150.00
112.800.150.150.00
112.850.150.150.00
112.900.150.150.00
112.950.150.150.00
113.000.150.150.00
113.050.190.150.04
113.100.260.160.10
113.150.340.160.19
113.200.450.160.29
113.250.560.160.40
113.300.690.160.53
113.350.830.160.66
113.400.980.170.81
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
113.451.140.170.97
113.501.300.171.13
113.551.440.171.27
113.601.560.171.39
113.651.670.171.50
113.701.770.171.59
113.751.860.181.68
113.801.950.181.77
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POST DEV NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 51
Stage-Area-Storage for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
110.800.0850.000
110.850.0850.002
110.900.0850.003
110.950.0850.005
111.000.0850.007
111.050.0850.008
111.100.0850.010
111.150.0850.012
111.200.0850.013
111.250.0850.015
111.300.0850.016
111.350.0850.017
111.400.0850.019
111.450.0850.021
111.500.0850.024
111.550.0850.026
111.600.0850.029
111.650.0850.031
111.700.0850.034
111.750.0850.037
111.800.0850.040
111.850.0850.042
111.900.0850.045
111.950.0850.048
112.000.0850.051
112.050.0850.054
112.100.0850.057
112.150.0850.060
112.200.0850.064
112.250.0850.067
112.300.0850.070
112.350.0850.073
112.400.0850.076
112.450.0850.079
112.500.0850.082
112.550.0850.085
112.600.0850.088
112.650.0850.091
112.700.0850.094
112.750.0850.097
112.800.0850.100
112.850.0850.103
112.900.0850.105
112.950.0850.108
113.000.0850.111
113.050.0850.113
113.100.0850.116
113.150.0850.118
113.200.0850.120
113.250.0850.122
113.300.0850.124
113.350.0850.125
113.400.0850.126
Elevation (feet)Surface (acres)Storage (acre-feet)
113.450.0850.128
113.500.0850.129
113.550.0850.131
113.600.0850.133
113.650.0850.134
113.700.0850.136
113.750.0850.138
113.800.0850.139
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 52
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS
Subcatchment1S: POROUS Runoff Area=0.570 ac 0.00% Impervious Runoff Depth>0.53" Flow Length=310' Tc=12.9 min CN=39 Runoff=0.11 cfs 0.025 af
Subcatchment2S: IMPERVIOUS
Subcatchment2S: IMPERVIOUS Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>5.81" Flow Length=310' Tc=13.1 min CN=98 Runoff=2.68 cfs 0.349 af
Subcatchment5S: IMPERVIOUS Runoff Area=0.270 ac 100.00% Impervious Runoff Depth>5.82" Flow Length=180' Slope=0.0100'/' Tc=1.6 min CN=98 Runoff=1.84 cfs 0.131 af
Runoff Area=0.190 ac 0.00% Impervious Runoff Depth>0.53"
Subcatchment6S: POROUS
Flow Length=250' Tc=12.4 min CN=39 Runoff=0.04 cfs 0.008 af
Subcatchment8S: PROP WAREHOUSE Runoff Area=0.460 ac 100.00% Impervious Runoff Depth>5.82" Flow Length=280' Slope=0.0100'/' Tc=2.6 min CN=98 Runoff=2.92 cfs 0.223 af
Subcatchment10S: BY-PASS POROUS Runoff Area=0.060 ac 0.00% Impervious Runoff Depth>0.54" Tc=2.0 min CN=39 Runoff=0.02 cfs 0.003 af
Subcatchment11S: BY-PASS Runoff Area=0.070 ac 100.00% Impervious Runoff Depth>5.82" Tc=2.0 min CN=98 Runoff=0.46 cfs 0.034 af
Inflow=1.47 cfs 0.252 af
Outflow=1.47 cfs 0.252 af
Reach 10: COMPOSITE
Pond 3P: SSIB #1 SURFACE BASIN Peak Elev= $ 112.33' $ Storage= $ 6,132 $ cf Inflow= $ 2.75 $ cfs 0.374 af Discarded= $ 0.11 $ cfs 0.093 af Primary= $ 1.30 $ cfs 0.199 af Outflow= $ 1.41 $ cfs 0.291 af
Pond 8P: SSIB #2 UNDERGROUND Peak Elev=109.14' Storage=0.059 af Inflow=1.84 cfs 0.139 af
Discarded=0.11 cfs 0.096 af Primary=0.12 cfs 0.012 af Outflow=0.22 cfs 0.108 af
Pond 9P: SSIB #3 UNDERGROUND Peak Elev=113.06' Storage=0.114 af Inflow=2.92 cfs 0.223 af Discarded=0.15 cfs 0.141 af Primary=0.05 cfs 0.004 af Outflow=0.21 cfs 0.146 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.773 af Average Runoff Depth = 3.97" 35.04% Pervious = 0.820 ac 64.96% Impervious = 1.520 ac
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 53
Summary for Subcatchment 1S: POROUS
Runoff = 0.11 cfs @ 12.55 hrs, Volume=
Runoff = 0.11 cfs @ 12.55 hrs, Volume= Routed to Pond 3P : SSIB #1 SURFACE BASIN 0.025 af, Depth> 0.53"
0.025 af, Depth> 0.53"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac) CN Description
0.570 39 >75% Grass cover, Good, HSG A
0.570 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n=0.240 P2=3.42"
0.3 50 0.0350 2.81 Shallow Concentrated Flow, Grassed Waterway Kv=15.0 fps
0.9 160 3.00 Direct Entry, PIPE FLOW
12.9 310 Total
Subcatchment 1S: POROUS
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 54
Summary for Subcatchment 2S: IMPERVIOUS
Runoff = 2.68 cfs @ 12.22 hrs, Volume= 0.349 af, Depth> 5.81" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac) CN Description
0.720 98 Paved parking, HSG A
0.720 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.5 50 0.0110 1.57
0.9 160 3.00 Direct Entry, PIPE FLOW
13.1 310 Total
Subcatchment 2S: IMPERVIOUS
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Summary for Subcatchment 5S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 1.84 cfs @ 12.08 hrs, Volume= 0.131 af, Depth> 5.82" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac) CN Description
0.270 98 Roofs, HSG A
0.270 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 50 0.0100 0.94 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.7 130 3.00 Direct Entry, PIPE FLOW
1.6 180 Total
Subcatchment 5S: IMPERVIOUS
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 56
Summary for Subcatchment 6S: POROUS
Runoff = 0.04 cfs @ 12.46 hrs, Volume= 0.008 af, Depth> 0.53" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac) CN Description
0.190 39 >75% Grass cover, Good, HSG A
0.190 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.3 90 0.0270 0.13 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Paved Kv= 20.3 fps
1.1 160 0.0150 2.49
12.4 250 Total
Subcatchment 6S: POROUS
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 57
Summary for Subcatchment 8S: PROP WAREHOUSE BLDG
[49] Hint: Tc<2dt may require smaller dt
Runoff = 2.92 cfs @ 12.10 hrs, Volume= 0.223 af, Depth> 5.82" Routed to Pond 9P : SSIB #3 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac) CN Description
0.460 98 Roofs, HSG A
0.460 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.5 100 0.0100 1.08 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.3 40 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fps
0.8 140 3.00 Direct Entry, PIPE FLOW
2.6 280 Total
Subcatchment 8S: PROP WAREHOUSE BLDG
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 58
Summary for Subcatchment 10S: BY-PASS POROUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.02 cfs @ 12.12 hrs, Volume= 0.003 af, Depth> 0.54" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac)CNDescription
0.06039>75% Grass cover, Good, HSG A
0.060100.00% Pervious Area
Tc (min)Length (feet)Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.0Direct Entry,
Subcatchment 10S: BY-PASS POROUS
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 59
Summary for Subcatchment 11S: BY-PASS IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.46 cfs @ 12.09 hrs, Volume= 0.034 af, Depth> 5.82" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25 year Rainfall=6.68"
Area (ac) CN Description
0.070 98 Paved parking, HSG A
0.070 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
Direct Entry,
Subcatchment 11S: BY-PASS IMPERVIOUS
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POST DEV NOA Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
NOAA 24-hr D 25 year Rainfall=6.68" Printed 12/31/2025 ns LLC Page 60
Summary for Reach 10: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.340 ac, 64.96% Impervious, Inflow Depth > 1.29" for 25 year event Inflow = 1.47 cfs @ 12.68 hrs, Volume= 0.252 af Outflow = 1.47 cfs @ 12.68 hrs, Volume= 0.252 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 10: COMPOSITE
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 61
Summary for Pond 3P: SSIB #1 SURFACE BASIN
[82] Warning: Early inflow requires earlier time span
Inflow Area = 1.290 ac, 55.81% Impervious, Inflow Depth > 3.48" for 25 year event Inflow = 2.75 cfs @ 12.23 hrs, Volume= 0.374 af Outflow = 1.41 cfs @ 12.65 hrs, Volume= 0.291 af, Atten=49%, Lag=25.4 min Discarded = 0.11 cfs @ 12.65 hrs, Volume= 0.093 af Primary = 1.30 cfs @ 12.65 hrs, Volume= 0.199 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 112.33' @ 12.65 hrs Surf.Area= 3,460 sf Storage= 6,132 cf Plug-Flow detention time= 120.4 min calculated for 0.290 af (78% of inflow) Center-of-Mass det. time= 58.6 min ( 813.8 - 755.2 )
VolumeInvertAvail.StorageStorage Description
#1110.00'12,950 cfCustom Stage Data (Prismatic)Listed below (Recalc)
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
110.002,00000
111.002,4502,2252,225
112.003,2002,8255,050
113.004,0003,6008,650
114.004,6004,30012,950
DeviceRoutingInvertOutlet Devices
#1Discarded110.00'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 106.00'
#2Primary111.50'12.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
#3Primary113.00'24.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.11 cfs @ 12.65 hrs HW=112.32' (Free Discharge) 1=Exfiltration (Controls 0.11 cfs)
Primary OutFlow Max=1.30 cfs @ 12.65 hrs HW=112.32' (Free Discharge) 2=Orifice/Grate (Orifice Controls 1.30 cfs @ 3.90 fps) 3=Orifice/Grate (Controls 0.00 cfs)
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Pond 3P: SSIB #1 SURFACE BASIN
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 63
Stage-Discharge for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.000.000.000.00112.651.720.131.59
110.050.050.050.00112.701.760.131.63
110.100.050.050.00112.751.800.131.67
110.150.050.050.00112.801.840.131.71
110.200.050.050.00112.851.880.131.74
110.250.050.050.00112.901.920.141.78
110.300.050.050.00112.951.950.141.82
110.350.050.050.00113.001.990.141.85
110.400.060.060.00113.052.470.142.33
110.450.060.060.00113.103.300.143.16
110.500.060.060.00113.154.380.144.23
110.550.060.060.00113.205.640.155.50
110.600.060.060.00113.257.070.156.92
110.650.060.060.00113.308.650.158.50
110.700.060.060.00113.3510.360.1510.21
110.750.060.060.00113.4012.190.1512.04
110.800.060.060.00113.4514.140.1513.99
110.850.070.070.00113.5016.200.1616.05
110.900.070.070.00113.5518.370.1618.21
110.950.070.070.00113.6020.630.1620.47
111.000.070.070.00113.6522.980.1622.82
111.050.070.070.00113.7025.430.1625.27
111.100.070.070.00113.7527.970.1727.80
111.150.070.070.00113.8030.590.1730.42
111.200.080.080.00113.8533.290.1733.12
111.250.080.080.00113.9036.070.1735.90
111.300.080.080.00113.9538.930.1738.76
111.350.080.080.00114.0041.140.1740.97
111.400.080.080.00
111.450.080.080.00
111.500.090.090.00
111.550.120.090.04
111.600.190.090.10
111.650.280.090.19
111.700.380.090.29
111.750.500.090.40
111.800.620.100.53
111.850.750.100.66
111.900.860.100.76
111.950.940.100.84
112.001.020.100.92
112.051.090.100.99
112.101.160.111.05
112.151.220.111.11
112.201.280.111.17
112.251.330.111.22
112.301.390.111.27
112.351.440.111.32
112.401.490.121.37
112.451.540.121.42
112.501.580.121.46
112.551.630.121.51
112.601.670.121.55
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 64
Stage-Area-Storage for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
110.002,0000
110.052,022101
110.102,045202
110.152,068305
110.202,090409
110.252,113514
110.302,135620
110.352,157728
110.402,180836
110.452,203946
110.502,2251,056
110.552,2471,168
110.602,2701,281
110.652,2931,395
110.702,3151,510
110.752,3381,627
110.802,3601,744
110.852,3821,863
110.902,4051,982
110.952,4282,103
111.002,4502,225
111.052,4872,348
111.102,5252,474
111.152,5632,601
111.202,6002,730
111.252,6382,861
111.302,6752,994
111.352,7123,128
111.402,7503,265
111.452,7883,403
111.502,8253,544
111.552,8623,686
111.602,9003,830
111.652,9383,976
111.702,9754,124
111.753,0134,273
111.803,0504,425
111.853,0874,578
111.903,1254,734
111.953,1634,891
112.003,2005,050
112.053,2405,211
112.103,2805,374
112.153,3205,539
112.203,3605,706
112.253,4005,875
112.303,4406,046
112.353,4806,219
112.403,5206,394
112.453,5606,571
112.503,6006,750
112.553,6406,931
112.603,6807,114
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
112.653,7207,299
112.703,7607,486
112.753,8007,675
112.803,8407,866
112.853,8808,059
112.903,9208,254
112.953,9608,451
113.004,0008,650
113.054,0308,851
113.104,0609,053
113.154,0909,257
113.204,1209,462
113.254,1509,669
113.304,1809,877
113.354,21010,087
113.404,24010,298
113.454,27010,511
113.504,30010,725
113.554,33010,941
113.604,36011,158
113.654,39011,377
113.704,42011,597
113.754,45011,819
113.804,48012,042
113.854,51012,267
113.904,54012,493
113.954,57012,721
114.004,60012,950
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 65
Summary for Pond 8P: SSIB #2 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 3.64" for 25 year event Inflow = 1.84 cfs @ 12.08 hrs, Volume= 0.139 af Outflow = 0.22 cfs @ 12.88 hrs, Volume= 0.108 af, Atten= 88%, Lag= 47.6 min Discarded = 0.11 cfs @ 12.88 hrs, Volume= 0.096 af Primary = 0.12 cfs @ 12.88 hrs, Volume= 0.012 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 109.14' @ 12.88 hrs Surf.Area= 0.064 ac Storage= 0.059 af Plug-Flow detention time= 151.0 min calculated for 0.108 af (77% of inflow) Center-of-Mass det. time= 86.4 min ( 828.2 - 741.8 )
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95"W x 66.33"L x 3.00"H Field A
0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 afTotal Available Storage
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W × 4.0" H Vert. Orifice/Grate C= 0.600\nLimited to weir flow at low heads
Discarded OutFlow Max=0.11 cfs @ 12.88 hrs HW=109.14' (Free Discharge) 1=Exfiltration (Controls 0.11 cfs)
Primary OutFlow Max=0.12 cfs @ 12.88 hrs HW=109.14' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.12 cfs @ 1.21 fps)
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NOAA 24-hr D 25 year Rainfall=6.68" Printed 12/31/2025 Page 66
POST DEV NOAA Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Pond 8P: SSIB #2 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 12 Rows x 28.0" Wide + 13.4" Spacing x 11 + 10.0" Side Stone x 2 = 41.95' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 36 Chambers x 62.0 cf + 40.28' Header x 3.10 sf x 2 = 2,481.8 cf Chamber Storage 36 Chambers x 78.4 cf + 40.28' Header x 3.92 sf x 2 = 3,137.9 cf Displacement 8,348.3 cf Field - 3,137.9 cf Chambers = 5,210.4 cf Stone x 40.0% Voids = 2,084.2 cf Stone Storage Chamber Storage + Stone Storage = 4,565.9 cf = 0.105 af Overall Storage Efficiency = 54.7% Overall System Size = 66.33' x 41.95' x 3.00'
36 Chambers 309.2 cy Field 193.0 cy Stone
0101010101010101010
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 67
Pond 8P: SSIB #2 UNDERGROUND
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 68
Stage-Discharge for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
107.500.000.000.00
107.550.070.070.00
107.600.070.070.00
107.650.070.070.00
107.700.070.070.00
107.750.070.070.00
107.800.070.070.00
107.850.070.070.00
107.900.070.070.00
107.950.080.080.00
108.000.080.080.00
108.050.080.080.00
108.100.080.080.00
108.150.080.080.00
108.200.080.080.00
108.250.080.080.00
108.300.090.090.00
108.350.090.090.00
108.400.090.090.00
108.450.090.090.00
108.500.090.090.00
108.550.090.090.00
108.600.090.090.00
108.650.090.090.00
108.700.100.100.00
108.750.100.100.00
108.800.100.100.00
108.850.100.100.00
108.900.100.100.00
108.950.100.100.00
109.000.100.100.00
109.050.130.100.02
109.100.170.110.07
109.150.230.110.12
109.200.300.110.19
109.250.380.110.27
109.300.460.110.35
109.350.550.110.44
109.400.620.110.50
109.450.680.110.56
109.500.730.120.61
109.550.770.120.66
109.600.820.120.70
109.650.860.120.74
109.700.900.120.78
109.750.940.120.81
109.800.970.120.85
109.851.010.120.88
109.901.040.130.91
109.951.070.130.95
110.001.100.130.98
110.051.130.131.00
110.101.160.131.03
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.151.190.131.06
110.201.220.131.09
110.251.250.141.11
110.301.270.141.14
110.351.300.141.16
110.401.330.141.19
110.451.350.141.21
110.501.380.141.23
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 69
Stage-Area-Storage for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
107.500.0640.000
107.550.0640.001
107.600.0640.003
107.650.0640.004
107.700.0640.005
107.750.0640.006
107.800.0640.008
107.850.0640.009
107.900.0640.010
107.950.0640.011
108.000.0640.012
108.050.0640.013
108.100.0640.014
108.150.0640.016
108.200.0640.018
108.250.0640.020
108.300.0640.022
108.350.0640.024
108.400.0640.026
108.450.0640.028
108.500.0640.030
108.550.0640.032
108.600.0640.034
108.650.0640.036
108.700.0640.039
108.750.0640.041
108.800.0640.043
108.850.0640.045
108.900.0640.048
108.950.0640.050
109.000.0640.052
109.050.0640.055
109.100.0640.057
109.150.0640.059
109.200.0640.062
109.250.0640.064
109.300.0640.066
109.350.0640.068
109.400.0640.071
109.450.0640.073
109.500.0640.075
109.550.0640.077
109.600.0640.079
109.650.0640.081
109.700.0640.083
109.750.0640.085
109.800.0640.087
109.850.0640.089
109.900.0640.090
109.950.0640.092
110.000.0640.093
110.050.0640.094
110.100.0640.095
Elevation (feet)Surface (acres)Storage (acre-feet)
110.150.0640.096
110.200.0640.097
110.250.0640.098
110.300.0640.100
110.350.0640.101
110.400.0640.102
110.450.0640.104
110.500.0640.105
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 70
Summary for Pond 9P: SSIB #3 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 100.00% Impervious, Inflow Depth > 5.82" for 25 year event Inflow = 2.92 cfs @ 12.10 hrs, Volume= 0.223 af Outflow = 0.21 cfs @ 13.40 hrs, Volume= 0.146 af, Atten= 93%, Lag= 78.6 min Discarded = 0.15 cfs @ 13.40 hrs, Volume= 0.141 af Primary = 0.05 cfs @ 13.40 hrs, Volume= 0.004 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 113.06' @ 13.40 hrs Surf.Area= 0.085 ac Storage= 0.114 af Plug-Flow detention time= 171.6 min calculated for 0.145 af (65% of inflow) Center-of-Mass det. time= 94.1 min ( 827.4 - 733.4 )
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A
0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 Inside #1 Inside = 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside = 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 afTotal Available Storage
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.15 cfs @ 13.40 hrs HW=113.06' (Free Discharge) 1=Exfiltration (Controls 0.15 cfs)
Primary OutFlow Max=0.05 cfs @ 13.40 hrs HW=113.06' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.05 cfs @ 0.81 fps)
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NOAA 24-hr D 25 year Rainfall=6.68" Printed 12/31/2025
POST DEV /N Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Page 71
Pond 9P: SSIB #3 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 16 Rows x 28.0" Wide + 13.4" Spacing x 15 + 10.0" Side Stone x 2 = 55.75' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 48 Chambers x 62.0 cf + 54.08' Header x 3.10 sf x 2 = 3,311.3 cf Chamber Storage 48 Chambers x 78.4 cf + 54.08' Header x 3.92 sf x 2 = 4,186.8 cf Displacement 11,094.6 cf Field - 4,186.8 cf Chambers = 6,907.8 cf Stone x 40.0% Voids = 2,763.1 cf Stone Storage Chamber Storage + Stone Storage = 6,074.4 cf = 0.139 af Overall Storage Efficiency = 54.8% Overall System Size = 66.33' x 55.75' x 3.00'
48 Chambers 410.9 cy Field 255.8 cy Stone
101010
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 72
Pond 9P: SSIB #3 UNDERGROUND
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 73
Stage-Discharge for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.800.000.000.00
110.850.090.090.00
110.900.090.090.00
110.950.090.090.00
111.000.090.090.00
111.050.090.090.00
111.100.090.090.00
111.150.100.100.00
111.200.100.100.00
111.250.100.100.00
111.300.100.100.00
111.350.100.100.00
111.400.100.100.00
111.450.110.110.00
111.500.110.110.00
111.550.110.110.00
111.600.110.110.00
111.650.110.110.00
111.700.110.110.00
111.750.110.110.00
111.800.120.120.00
111.850.120.120.00
111.900.120.120.00
111.950.120.120.00
112.000.120.120.00
112.050.120.120.00
112.100.130.130.00
112.150.130.130.00
112.200.130.130.00
112.250.130.130.00
112.300.130.130.00
112.350.130.130.00
112.400.130.130.00
112.450.140.140.00
112.500.140.140.00
112.550.140.140.00
112.600.140.140.00
112.650.140.140.00
112.700.140.140.00
112.750.150.150.00
112.800.150.150.00
112.850.150.150.00
112.900.150.150.00
112.950.150.150.00
113.000.150.150.00
113.050.190.150.04
113.100.260.160.10
113.150.340.160.19
113.200.450.160.29
113.250.560.160.40
113.300.690.160.53
113.350.830.160.66
113.400.980.170.81
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
113.451.140.170.97
113.501.300.171.13
113.551.440.171.27
113.601.560.171.39
113.651.670.171.50
113.701.770.171.59
113.751.860.181.68
113.801.950.181.77
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POST DEV NOAA 24-hr D 25 year Rainfall=6.68" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 74
Stage-Area-Storage for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
110.800.0850.000
110.850.0850.002
110.900.0850.003
110.950.0850.005
111.000.0850.007
111.050.0850.008
111.100.0850.010
111.150.0850.012
111.200.0850.013
111.250.0850.015
111.300.0850.016
111.350.0850.017
111.400.0850.019
111.450.0850.021
111.500.0850.024
111.550.0850.026
111.600.0850.029
111.650.0850.031
111.700.0850.034
111.750.0850.037
111.800.0850.040
111.850.0850.042
111.900.0850.045
111.950.0850.048
112.000.0850.051
112.050.0850.054
112.100.0850.057
112.150.0850.060
112.200.0850.064
112.250.0850.067
112.300.0850.070
112.350.0850.073
112.400.0850.076
112.450.0850.079
112.500.0850.082
112.550.0850.085
112.600.0850.088
112.650.0850.091
112.700.0850.094
112.750.0850.097
112.800.0850.100
112.850.0850.103
112.900.0850.105
112.950.0850.108
113.000.0850.111
113.050.0850.113
113.100.0850.116
113.150.0850.118
113.200.0850.120
113.250.0850.122
113.300.0850.124
113.350.0850.125
113.400.0850.126
Elevation (feet)Surface (acres)Storage (acre-feet)
113.450.0850.128
113.500.0850.129
113.550.0850.131
113.600.0850.133
113.650.0850.134
113.700.0850.136
113.750.0850.138
113.800.0850.139
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 75
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS
Subcatchment1S: POROUS Runoff Area=0.570 ac 0.00% Impervious Runoff Depth>1.57" Flow Length=310' Tc=12.9 min CN=39 Runoff=0.52 cfs 0.075 af
Subcatchment2S: IMPERVIOUS
Subcatchment2S: IMPERVIOUS Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>8.29" Flow Length=310' Tc=13.1 min CN=98 Runoff=3.82 cfs 0.498 af
Subcatchment5S: IMPERVIOUS Runoff Area=0.270 ac 100.00% Impervious Runoff Depth>8.30" Flow Length=180' Slope=0.0100'/' Tc=1.6 min CN=98 Runoff=2.61 cfs 0.187 af
Subcatchment6S: POROUS
Subcatchment6S: POROUS Runoff Area=0.190 ac 0.00% Impervious Runoff Depth>1.57"
Flow Length=250' Tc=12.4 min CN=39 Runoff=0.18 cfs 0.025 af
Subcatchment8S: PROP WAREHOUSE Runoff Area=0.460 ac 100.00% Impervious Runoff Depth>8.30" Flow Length=280' Slope=0.0100'/' Tc=2.6 min CN=98 Runoff=4.15 cfs 0.318 af
Subcatchment10S: BY-PASSPOROUS Runoff Area=0.060 ac 0.00% Impervious Runoff Depth>1.59" Tc=2.0 min CN=39 Runoff=0.12 cfs 0.008 af
Runoff Area=0.070 ac 100.00% Impervious Runoff Depth>8.30" Tc=2.0 min CN=98 Runoff=0.66 cfs 0.048 af
Subcatchment11S: BY-PASS
Inflow=3.71 cfs 0.581 af
Outflow=3.71 cfs 0.581 af
Reach 10: COMPOSITE
Pond 3P: SSIB #1 SURFACE BASIN Peak Elev= $ 113.01' $ Storage= $ 8,676 $ cf Inflow= $ 4.30 $ cfs 0.572 af Discarded= $ 0.14 $ cfs 0.101 af Primary= $ 1.91 $ cfs 0.385 af Outflow= $ 2.05 $ cfs 0.486 af
Pond 8P: SSIB #2 UNDERGROUND Peak Elev=109.52' Storage=0.076 af Inflow=2.68 cfs 0.212 af
Discarded=0.12 cfs 0.105 af Primary=0.63 cfs 0.065 af Outflow=0.74 cfs 0.170 af
Pond 9P: SSIB #3 UNDERGROUND Peak Elev=113.57' Storage=0.132 af Inflow=4.15 cfs 0.318 af Discarded=0.17 cfs 0.153 af Primary=1.32 cfs 0.075 af Outflow=1.49 cfs 0.228 af
Total Runoff Area = 2.340 ac Runoff Volume = 1.158 af Average Runoff Depth = 5.94" 35.04% Pervious = 0.820 ac 64.96% Impervious = 1.520 ac
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 76
Summary for Subcatchment 1S: POROUS
Runoff = 0.52 cfs @ 12.27 hrs, Volume= Routed to Pond 3P : SSIB #1 SURFACE BASIN 0.075 af, Depth> 1.57"
0.075 af, Depth> 1.57"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.570 39 >75% Grass cover, Good, HSG A
0.570 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.3 50 0.0350 2.81
0.9 160 3.00 Direct Entry, PIPE FLOW
12.9 310 Total
Subcatchment 1S: POROUS
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 77
Summary for Subcatchment 2S: IMPERVIOUS
Runoff = 3.82 cfs @ 12.22 hrs, Volume= Routed to Pond 3P : SSIB #1 SURFACE BASIN 0.498 af, Depth> 8.29"
0.498 af, Depth> 8.29"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.720 98 Paved parking, HSG A
0.720 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.5 50 0.0110 1.57
0.9 160 3.00 Direct Entry, PIPE FLOW
13.1 310 Total
Subcatchment 2S: IMPERVIOUS
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 78
Summary for Subcatchment 5S: IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 2.61 cfs @ 12.08 hrs, Volume= 0.187 af, Depth> 8.30" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.270 98 Roofs, HSG A
0.270 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 50 0.0100 0.94 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.7 130 3.00 Direct Entry, PIPE FLOW
1.6 180 Total
Subcatchment 5S: IMPERVIOUS
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 79
Summary for Subcatchment 6S: POROUS
Runoff = 0.18 cfs @ 12.27 hrs, Volume= 0.025 af, Depth> 1.57" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.190 39 >75% Grass cover, Good, HSG A
0.190 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.3 90 0.0270 0.13 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Paved Kv= 20.3 fps
1.1 160 0.0150 2.49
12.4 250 Total
Subcatchment 6S: POROUS
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 80
Summary for Subcatchment 8S: PROP WAREHOUSE BLDG
[49] Hint: Tc<2dt may require smaller dt
Runoff = 4.15 cfs @ 12.10 hrs, Volume= 0.318 af, Depth> 8.30" Routed to Pond 9P : SSIB #3 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.460 98 Roofs, HSG A
0.460 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.5 100 0.0100 1.08 Sheet Flow,
0.3 40 0.0100 2.03 Smooth surfaces n= 0.011 P2= 3.42"
0.8 140 3.00 Shallow Concentrated Flow, Paved Kv= 20.3 fps
Direct Entry, PIPE FLOW
2.6 280 Total
Subcatchment 8S: PROP WAREHOUSE BLDG
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 81
Summary for Subcatchment 10S: BY-PASS POROUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.12 cfs @ 12.10 hrs, Volume= 0.008 af, Depth> 1.59" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac)CNDescription
0.06039>75% Grass cover, Good, HSG A
0.060100.00% Pervious Area
Tc (min)Length (feet)Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.0Direct Entry,
Subcatchment 10S: BY-PASS POROUS
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 82
Summary for Subcatchment 11S: BY-PASS IMPERVIOUS
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.66 cfs @ 12.09 hrs, Volume= 0.048 af, Depth> 8.30" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100 YEAR Rainfall=9.48"
Area (ac) CN Description
0.070 98 Paved parking, HSG A
0.070 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
Direct Entry,
Subcatchment 11S: BY-PASS IMPERVIOUS
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 83
Summary for Reach 10: COMPOSITE
[40] Hint: Not Described (Outflow=Inflow)
Inflow Area = 2.340 ac, 64.96% Impervious, Inflow Depth > 2.98" for 100 YEAR event Inflow = 3.71 cfs @ 12.31 hrs, Volume= 0.581 af Outflow = 3.71 cfs @ 12.31 hrs, Volume= 0.581 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 10: COMPOSITE
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 84
Summary for Pond 3P: SSIB #1 SURFACE BASIN
[82] Warning: Early inflow requires earlier time span
Inflow Area = 1.290 ac, 55.81% Impervious, Inflow Depth > 5.32" for 100 YEAR event Inflow = 4.30 cfs @ 12.23 hrs, Volume= 0.572 af Outflow = 2.05 cfs @ 12.70 hrs, Volume= 0.486 af, Atten= 52%, Lag= 28.4 min Discarded = 0.14 cfs @ 12.70 hrs, Volume= 0.101 af Primary = 1.91 cfs @ 12.70 hrs, Volume= 0.385 af Routed to Reach 10: COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 113.01' @ 12.70 hrs Surf.Area= 4,004 sf Storage= 8,676 cf Plug-Flow detention time= 108.1 min calculated for 0.486 af (85% of inflow) Center-of-Mass det. time= 59.5 min (818.6 - 759.0)
VolumeInvertAvail.StorageStorage Description
#1110.00'12,950 cfCustom Stage Data (Prismatic)Listed below (Recalc)
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
110.002,00000
111.002,4502,2252,225
112.003,2002,8255,050
113.004,0003,6008,650
114.004,6004,30012,950
DeviceRoutingInvertOutlet Devices
#1Discarded110.00'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 106.00'
#2Primary111.50'12.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
#3Primary113.00'24.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.14 cfs @ 12.70 hrs HW=113.01' (Free Discharge) 1=Exfiltration (Controls 0.14 cfs)
Primary OutFlow Max=1.88 cfs @ 12.70 hrs HW=113.01' (Free Discharge) 2=Orifice/Grate (Orifice Controls 1.86 cfs @ 5.57 fps) 3=Orifice/Grate (Weir Controls 0.02 cfs @ 0.26 fps)
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 85
Pond 3P: SSIB #1 SURFACE BASIN
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 86
Stage-Discharge for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.000.000.000.00112.651.720.131.59
110.050.050.050.00112.701.760.131.63
110.100.050.050.00112.751.800.131.67
110.150.050.050.00112.801.840.131.71
110.200.050.050.00112.851.880.131.74
110.250.050.050.00112.901.920.141.78
110.300.050.050.00112.951.950.141.82
110.350.050.050.00113.001.990.141.85
110.400.060.060.00113.052.470.142.33
110.450.060.060.00113.103.300.143.16
110.500.060.060.00113.154.380.144.23
110.550.060.060.00113.205.640.155.50
110.600.060.060.00113.257.070.156.92
110.650.060.060.00113.308.650.158.50
110.700.060.060.00113.3510.360.1510.21
110.750.060.060.00113.4012.190.1512.04
110.800.060.060.00113.4514.140.1513.99
110.850.070.070.00113.5016.200.1616.05
110.900.070.070.00113.5518.370.1618.21
110.950.070.070.00113.6020.630.1620.47
111.000.070.070.00113.6522.980.1622.82
111.050.070.070.00113.7025.430.1625.27
111.100.070.070.00113.7527.970.1727.80
111.150.070.070.00113.8030.590.1730.42
111.200.080.080.00113.8533.290.1733.12
111.250.080.080.00113.9036.070.1735.90
111.300.080.080.00113.9538.930.1738.76
111.350.080.080.00114.0041.140.1740.97
111.400.080.080.00
111.450.080.080.00
111.500.090.090.00
111.550.120.090.04
111.600.190.090.10
111.650.280.090.19
111.700.380.090.29
111.750.500.090.40
111.800.620.100.53
111.850.750.100.66
111.900.860.100.76
111.950.940.100.84
112.001.020.100.92
112.051.090.100.99
112.101.160.111.05
112.151.220.111.11
112.201.280.111.17
112.251.330.111.22
112.301.390.111.27
112.351.440.111.32
112.401.490.121.37
112.451.540.121.42
112.501.580.121.46
112.551.630.121.51
112.601.670.121.55
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 87
Stage-Area-Storage for Pond 3P: SSIB #1 SURFACE BASIN
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
110.002,0000
110.052,022101
110.102,045202
110.152,068305
110.202,090409
110.252,113514
110.302,135620
110.352,157728
110.402,180836
110.452,203946
110.502,2251,056
110.552,2471,168
110.602,2701,281
110.652,2931,395
110.702,3151,510
110.752,3381,627
110.802,3601,744
110.852,3821,863
110.902,4051,982
110.952,4282,103
111.002,4502,225
111.052,4872,348
111.102,5252,474
111.152,5632,601
111.202,6002,730
111.252,6382,861
111.302,6752,994
111.352,7123,128
111.402,7503,265
111.452,7883,403
111.502,8253,544
111.552,8623,686
111.602,9003,830
111.652,9383,976
111.702,9754,124
111.753,0134,273
111.803,0504,425
111.853,0874,578
111.903,1254,734
111.953,1634,891
112.003,2005,050
112.053,2405,211
112.103,2805,374
112.153,3205,539
112.203,3605,706
112.253,4005,875
112.303,4406,046
112.353,4806,219
112.403,5206,394
112.453,5606,571
112.503,6006,750
112.553,6406,931
112.603,6807,114
Elevation (feet)Surface (sq-ft)Storage (cubic-feet)
112.653,7207,299
112.703,7607,486
112.753,8007,675
112.803,8407,866
112.853,8808,059
112.903,9208,254
112.953,9608,451
113.004,0008,650
113.054,0308,851
113.104,0609,053
113.154,0909,257
113.204,1209,462
113.254,1509,669
113.304,1809,877
113.354,21010,087
113.404,24010,298
113.454,27010,511
113.504,30010,725
113.554,33010,941
113.604,36011,158
113.654,39011,377
113.704,42011,597
113.754,45011,819
113.804,48012,042
113.854,51012,267
113.904,54012,493
113.954,57012,721
114.004,60012,950
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 88
Summary for Pond 8P: SSIB #2 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 5.52" for 100 YEAR event Inflow = 2.68 cfs @ 12.08 hrs, Volume= 0.212 af Outflow = 0.74 cfs @ 12.35 hrs, Volume= 0.170 af, Atten=72%, Lag=15.9 min Discarded = 0.12 cfs @ 12.35 hrs, Volume= 0.105 af Primary = 0.63 cfs @ 12.35 hrs, Volume= 0.065 af Routed to Reach 10: COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 109.52' @ 12.35 hrs Surf.Area= 0.064 ac Storage= 0.076 af Plug-Flow detention time= 113.4 min calculated for 0.169 af (80% of inflow) Center-of-Mass det. time= 54.7 min (800.7 - 746.0)
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95"W x 66.33"L x 3.00"H Field A
0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 afTotal Available Storage
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W × 4.0" H Vert. Orifice/Grate C= 0.600\nLimited to weir flow at low heads
Discarded OutFlow Max=0.12 cfs @ 12.35 hrs HW=109.52' (Free Discharge) 1=Exfiltration (Controls 0.12 cfs)
Primary OutFlow Max=0.63 cfs @ 12.35 hrs HW=109.52' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.63 cfs @ 2.82 fps)
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 89
Pond 8P: SSIB #2 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 12 Rows x 28.0" Wide + 13.4" Spacing x 11 + 10.0" Side Stone x 2 = 41.95' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 36 Chambers x 62.0 cf + 40.28' Header x 3.10 sf x 2 = 2,481.8 cf Chamber Storage 36 Chambers x 78.4 cf + 40.28' Header x 3.92 sf x 2 = 3,137.9 cf Displacement 8,348.3 cf Field - 3,137.9 cf Chambers = 5,210.4 cf Stone x 40.0% Voids = 2,084.2 cf Stone Storage Chamber Storage + Stone Storage = 4,565.9 cf = 0.105 af Overall Storage Efficiency = 54.7% Overall System Size = 66.33' x 41.95' x 3.00'
36 Chambers 309.2 cy Field 193.0 cy Stone
010101
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 90
Pond 8P: SSIB #2 UNDERGROUND
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 91
Stage-Discharge for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
107.500.000.000.00
107.550.070.070.00
107.600.070.070.00
107.650.070.070.00
107.700.070.070.00
107.750.070.070.00
107.800.070.070.00
107.850.070.070.00
107.900.070.070.00
107.950.080.080.00
108.000.080.080.00
108.050.080.080.00
108.100.080.080.00
108.150.080.080.00
108.200.080.080.00
108.250.080.080.00
108.300.090.090.00
108.350.090.090.00
108.400.090.090.00
108.450.090.090.00
108.500.090.090.00
108.550.090.090.00
108.600.090.090.00
108.650.090.090.00
108.700.100.100.00
108.750.100.100.00
108.800.100.100.00
108.850.100.100.00
108.900.100.100.00
108.950.100.100.00
109.000.100.100.00
109.050.130.100.02
109.100.170.110.07
109.150.230.110.12
109.200.300.110.19
109.250.380.110.27
109.300.460.110.35
109.350.550.110.44
109.400.620.110.50
109.450.680.110.56
109.500.730.120.61
109.550.770.120.66
109.600.820.120.70
109.650.860.120.74
109.700.900.120.78
109.750.940.120.81
109.800.970.120.85
109.851.010.120.88
109.901.040.130.91
109.951.070.130.95
110.001.100.130.98
110.051.130.131.00
110.101.160.131.03
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.151.190.131.06
110.201.220.131.09
110.251.250.141.11
110.301.270.141.14
110.351.300.141.16
110.401.330.141.19
110.451.350.141.21
110.501.380.141.23
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 92
Stage-Area-Storage for Pond 8P: SSIB #2 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
107.500.0640.000
107.550.0640.001
107.600.0640.003
107.650.0640.004
107.700.0640.005
107.750.0640.006
107.800.0640.008
107.850.0640.009
107.900.0640.010
107.950.0640.011
108.000.0640.012
108.050.0640.013
108.100.0640.014
108.150.0640.016
108.200.0640.018
108.250.0640.020
108.300.0640.022
108.350.0640.024
108.400.0640.026
108.450.0640.028
108.500.0640.030
108.550.0640.032
108.600.0640.034
108.650.0640.036
108.700.0640.039
108.750.0640.041
108.800.0640.043
108.850.0640.045
108.900.0640.048
108.950.0640.050
109.000.0640.052
109.050.0640.055
109.100.0640.057
109.150.0640.059
109.200.0640.062
109.250.0640.064
109.300.0640.066
109.350.0640.068
109.400.0640.071
109.450.0640.073
109.500.0640.075
109.550.0640.077
109.600.0640.079
109.650.0640.081
109.700.0640.083
109.750.0640.085
109.800.0640.087
109.850.0640.089
109.900.0640.090
109.950.0640.092
110.000.0640.093
110.050.0640.094
110.100.0640.095
Elevation (feet)Surface (acres)Storage (acre-feet)
110.150.0640.096
110.200.0640.097
110.250.0640.098
110.300.0640.100
110.350.0640.101
110.400.0640.102
110.450.0640.104
110.500.0640.105
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 93
Summary for Pond 9P: SSIB #3 UNDERGROUND
[82] Warning: Early inflow requires earlier time span
Inflow Area = 0.460 ac, 100.00% Impervious, Inflow Depth > 8.30" for 100 YEAR event Inflow = 4.15 cfs @ 12.10 hrs, Volume= 0.318 af Outflow = 1.49 cfs @ 12.27 hrs, Volume= 0.228 af, Atten= 64%, Lag= 10.6 min Discarded = 0.17 cfs @ 12.27 hrs, Volume= 0.153 af Primary = 1.32 cfs @ 12.27 hrs, Volume= 0.075 af Routed to Reach 10 : COMPOSITE Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 113.57' @ 12.27 hrs Surf.Area= 0.085 ac Storage= 0.132 af Plug-Flow detention time= 134.7 min calculated for 0.228 af (72% of inflow) Center-of-Mass det. time= 64.8 min (797.2 - 732.4)
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A
0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 afTotal Available Storage
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.17 cfs @ 12.27 hrs HW=113.56' (Free Discharge) 1=Exfiltration (Controls 0.17 cfs)
Primary OutFlow Max=1.30 cfs @ 12.27 hrs HW=113.56' (Free Discharge) 2=Orifice/Grate (Orifice Controls 1.30 cfs @ 2.61 fps)
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 94
Pond 9P: SSIB #3 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 16 Rows x 28.0" Wide + 13.4" Spacing x 15 + 10.0" Side Stone x 2 = 55.75' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 48 Chambers x 62.0 cf + 54.08' Header x 3.10 sf x 2 = 3,311.3 cf Chamber Storage 48 Chambers x 78.4 cf + 54.08' Header x 3.92 sf x 2 = 4,186.8 cf Displacement 11,094.6 cf Field - 4,186.8 cf Chambers = 6,907.8 cf Stone x 40.0% Voids = 2,763.1 cf Stone Storage Chamber Storage + Stone Storage = 6,074.4 cf = 0.139 af Overall Storage Efficiency = 54.8% Overall System Size = 66.33' x 55.75' x 3.00'
48 Chambers 410.9 cy Field 255.8 cy Stone
[○1○1○
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 95
Pond 9P: SSIB #3 UNDERGROUND
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 96
Stage-Discharge for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
110.800.000.000.00
110.850.090.090.00
110.900.090.090.00
110.950.090.090.00
111.000.090.090.00
111.050.090.090.00
111.100.090.090.00
111.150.100.100.00
111.200.100.100.00
111.250.100.100.00
111.300.100.100.00
111.350.100.100.00
111.400.100.100.00
111.450.110.110.00
111.500.110.110.00
111.550.110.110.00
111.600.110.110.00
111.650.110.110.00
111.700.110.110.00
111.750.110.110.00
111.800.120.120.00
111.850.120.120.00
111.900.120.120.00
111.950.120.120.00
112.000.120.120.00
112.050.120.120.00
112.100.130.130.00
112.150.130.130.00
112.200.130.130.00
112.250.130.130.00
112.300.130.130.00
112.350.130.130.00
112.400.130.130.00
112.450.140.140.00
112.500.140.140.00
112.550.140.140.00
112.600.140.140.00
112.650.140.140.00
112.700.140.140.00
112.750.150.150.00
112.800.150.150.00
112.850.150.150.00
112.900.150.150.00
112.950.150.150.00
113.000.150.150.00
113.050.190.150.04
113.100.260.160.10
113.150.340.160.19
113.200.450.160.29
113.250.560.160.40
113.300.690.160.53
113.350.830.160.66
113.400.980.170.81
Elevation (feet)Discharge (cfs)Discarded (cfs)Primary (cfs)
113.451.140.170.97
113.501.300.171.13
113.551.440.171.27
113.601.560.171.39
113.651.670.171.50
113.701.770.171.59
113.751.860.181.68
113.801.950.181.77
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POST DEV NOAA 24-hr D 100 YEAR Rainfall=9.48" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 97
Stage-Area-Storage for Pond 9P: SSIB #3 UNDERGROUND
Elevation (feet)Surface (acres)Storage (acre-feet)
110.800.0850.000
110.850.0850.002
110.900.0850.003
110.950.0850.005
111.000.0850.007
111.050.0850.008
111.100.0850.010
111.150.0850.012
111.200.0850.013
111.250.0850.015
111.300.0850.016
111.350.0850.017
111.400.0850.019
111.450.0850.021
111.500.0850.024
111.550.0850.026
111.600.0850.029
111.650.0850.031
111.700.0850.034
111.750.0850.037
111.800.0850.040
111.850.0850.042
111.900.0850.045
111.950.0850.048
112.000.0850.051
112.050.0850.054
112.100.0850.057
112.150.0850.060
112.200.0850.064
112.250.0850.067
112.300.0850.070
112.350.0850.073
112.400.0850.076
112.450.0850.079
112.500.0850.082
112.550.0850.085
112.600.0850.088
112.650.0850.091
112.700.0850.094
112.750.0850.097
112.800.0850.100
112.850.0850.103
112.900.0850.105
112.950.0850.108
113.000.0850.111
113.050.0850.113
113.100.0850.116
113.150.0850.118
113.200.0850.120
113.250.0850.122
113.300.0850.124
113.350.0850.125
113.400.0850.126
Elevation (feet)Surface (acres)Storage (acre-feet)
113.450.0850.128
113.500.0850.129
113.550.0850.131
113.600.0850.133
113.650.0850.134
113.700.0850.136
113.750.0850.138
113.800.0850.139
Page 134 Download HTML
APPENDIX C COLLECTION SYSTEM CALCULATIONS
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STORM SEWER TABULATION
PROFESSIONAL DESIGN SERVICES, L.L.C. 1245 AIRPORT ROAD, SUITE 1 LAKEWOOD, NJ 08701 (732) 363-0060
COMPUTED BY: ___ DATE: 12/9/2025
DESIGN STORM FREQUENCY: 25____ YEAR
INTENSITY CURVE: ___
PDS# 320157
LOCATION RUNOFF DATA SEWER DESIGN DATA
STRUCTURE # TIME OF CONCENTRATION PIPE MATERIAL MANNINGS AN 3
UPSTREAM DOWNSTREAM AREA WEIGHT OF RUNOFF COEFFICIENT TOTAL OVERLAND THROUGH AREA (7 A) THROUGH AREA (T P) ACCUMULATED RAINFALL INTENSITY PEAK RUNOFF DIAMETER LENGTH SLOPE CAPACITY AT FULL FLOW VELOCITY AT FULL FLOW VELOCITY ACTUAL
(AC) C A × C (3A × C) (MIN) (MIN) (MIN) (IN/HR) (CFS) (INCHES) (FT) (%) (CFS) (FPS)
(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16)
5 FES 1 0.18 30 0.05 0.05 15 15 5.7 0.3 15 153 0.50 5.9 4.8
O/S 3 2 1.3 15 10 0.50 5.9 4.8
2 3 0.16 80 0.13 0.13 15 15 5.7 2.0 15 47 0.50 5.9 4.8
3 4 0.16 80 0.13 0.26 15 1 16 5.5 2.7 15 161 0.50 5.9 4.8
4 FES 2 0.03 80 0.02 0.28 15 1 17 5.3 2.8 15 52 0.50 5.9 4.8
9 MH 5 0.23 60 0.14 0.14 15 15 5.7 0.8 15 43 0.50 5.9 4.8
8 MH 7 0.24 70 0.17 0.17 15 15 5.7 1.0 15 47 0.50 5.9 4.8
6 FES 3 0.14 90 0.13 0.13 15 15 5.7 0.8 15 5 0.50 5.9 4.8
O/S 1 MH 6 1.9 15 30 0.50 5.9 4.8
O/S 2 MH 6 0.6 15 20 0.50 5.9 4.8
MH 6 7 2.5 15 39 0.50 5.9 4.8
7 FES 4 0.07 90 0.06 0.06 15 15 5.7 2.8 15 12 0.50 5.9 4.8
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APPENDIX D SOIL EROSION COMPUTATIONS
Adherence to the Standards for Soil Erosion and Sediment Control Standards requires basin routings based upon the presumption that the basins and recharge systems are full to the elevation of the first outlet structure for the 2 and 10 year storm events. The enclosed routings show that safe passage of the 2 and 10 year storm events will result for all cases, indicating compliance.
Note that computations are based upon no ex-filtration from any SSIB, and the presumption that it is full to the first outlet.
1. Rip Rap Apron
for Tw > 1/2 Do
q=Q/Wo La=3(q/Do^{0.5}) Wa=3Wo+0.4La D50=(0.02q^{1.33})/Tw
for Tw <1/2 Do
q=Q/Wo La= 1.8(q/Do^{0.5}) + 7Do W= 3Wo + La D50=(0.02q^{1.33})/Tw
IDQ 25qTwWoLaWaD50 (inches)
FES 10.300.240.121.250.654.00.30
FES 22.82.240.121.256.06.26
FES 30.80.640.121.251.74.51.1
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2.Scour Hole
FES # 4 use scour hole
Let y=Do
D50=0.0082 q1.33/(Tw)
Find D50 = 0.09
Use D50 = 3 inches
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OCSCD
Prepared by Professional Design Services Printed 12/31/2025
HydroCAD\circledR 10.20-6a s/n 02223\circledC 2024 HydroCAD Software Solutions LLC Page 2
Rainfall Events Listing (selected events)
Event#Event NameStorm TypeCurveModeDuration (hours)B/BDepth (inches)AMC
12 YEARNOAA 24-hrDDefault24.0013.422
210 YEARNOAA 24-hrDDefault24.0015.382
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OCSCD
Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Area Listing (all nodes)
Area (acres)CNDescription (subcatchment-numbers)
0.60039>75% Grass cover, Good, HSG A (1S, 6S, 10S)
0.79098Paved parking, HSG A (2S, 11S)
0.73098Roofs, HSG A (5S, 8S)
2.12081TOTAL AREA
Printed 12/31/2025 Page 3
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OCSCD
Prepared by Professional Design Services HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC
Soil Listing (all nodes)
Area (acres)Soil GroupSubcatchment Numbers
2.120HSG A1S, 2S, 5S, 6S, 8S, 10S, 11S
0.000HSG B
0.000HSG C
0.000HSG D
0.000Other
2.120TOTAL AREA
Printed 12/31/2025 Page 4
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OCSCD
Prepared by Professional Design Services Printed 12/31/2025
HydroCAD\circledR 10.20-6a s/n 02223\circledC 2024 HydroCAD Software Solutions LLC Page 5
Ground Covers (all nodes)
HSG-A (acres)HSG-B (acres)HSG-C (acres)HSG-D (acres)Other (acres)Total (acres)Ground CoverSubcatchment Numbers
0.6000.0000.0000.0000.0000.600>75% Grass cover, Good1S, 6S, 10S
0.7900.0000.0000.0000.0000.790Paved parking2S, 11S
0.7300.0000.0000.0000.0000.730Roofs5S, 8S
2.1200.0000.0000.0000.0002.120TOTAL AREA
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 6
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS
Subcatchment1S: POROUS Runoff Area=0.350 ac 0.00% Impervious Runoff Depth>0.00" Flow Length=310' Tc=12.9 min CN=39 Runoff=0.00 cfs 0.000 af
Subcatchment2S: IMPERVIOUS
Subcatchment2S: IMPERVIOUS Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>2.91" Flow Length=310' Tc=13.1 min CN=98 Runoff=1.36 cfs 0.175 af
Subcatchment5S: IMPERVIOUS Runoff Area=0.270 ac 100.00% Impervious Runoff Depth>2.92" Flow Length=180' Slope=0.0100'/' Tc=1.6 min CN=98 Runoff=0.93 cfs 0.066 af
Subcatchment6S: POROUS
Subcatchment6S: POROUS Runoff Area=0.190 ac 0.00% Impervious Runoff Depth>0.00"
Flow Length=250' Tc=12.4 min CN=39 Runoff=0.00 cfs 0.000 af
Subcatchment8S: PROP WAREHOUSE Runoff Area=0.460 ac 100.00% Impervious Runoff Depth>2.92" Flow Length=280' Slope=0.0100'/' Tc=2.6 min CN=98 Runoff=1.48 cfs 0.112 af
Runoff Area=0.060 ac 0.00% Impervious Runoff Depth>0.00" Tc=2.0 min CN=39 Runoff=0.00 cfs 0.000 af
Subcatchment10S: BY-PASS POROUS
Runoff Area=0.070 ac 100.00% Impervious Runoff Depth>2.92" Tc=2.0 min CN=98 Runoff=0.24 cfs 0.017 af
Subcatchment11S: BY-PASS
Inflow=2.25 cfs 0.362 af
Outflow=2.25 cfs 0.362 af
Reach 10: COMPOSITE
Pond 3P: SSIB #1 SURFACE BASIN Peak Elev=111.97' Storage=4,951 cf Inflow=1.36 cfs 0.175 af Discarded=0.00 cfs 0.000 af Primary=0.87 cfs 0.171 af Outflow=0.87 cfs 0.171 af
Pond 8P: SSIB #2 UNDERGROUND Peak Elev=109.35' Storage=0.068 af Inflow=0.93 cfs 0.066 af
Discarded=0.00 cfs 0.000 af Primary=0.44 cfs 0.064 af Outflow=0.44 cfs 0.064 af
Pond 9P: SSIB #3 UNDERGROUND Peak Elev=113.49' Storage=0.129 af Inflow=1.48 cfs 0.112 af Discarded=0.00 cfs 0.000 af Primary=1.09 cfs 0.110 af Outflow=1.09 cfs 0.110 af
Total Runoff Area = 2.120 ac Runoff Volume = 0.369 af Average Runoff Depth = 2.09" 28.30% Pervious = 0.600 ac 71.70% Impervious = 1.520 ac
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 1S: POROUS
Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.350 39 >75% Grass cover, Good, HSG A
0.350 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42"
0.3 50 0.0350 2.81 Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.9 160 3.00 Direct Entry, PIPE FLOW
12.9 310 Total
Subcatchment 1S: POROUS
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2S: IMPERVIOUS
Runoff = 1.36 cfs @ 12.22 hrs, Volume= Routed to Pond 3P : SSIB #1 SURFACE BASIN 0.175 af, Depth> 2.91"
0.175 af, Depth> 2.91"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.720 98 Paved parking, HSG A
0.720 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.5 50 0.0110 1.57
0.9 160 3.00 Direct Entry, PIPE FLOW
13.1 310 Total
Subcatchment 2S: IMPERVIOUS
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 5S: IMPERVIOUS
Runoff = 0.93 cfs @ 12.08 hrs, Volume= 0.066 af, Depth> 2.92" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.270 98 Roofs, HSG A
0.270 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 50 0.0100 0.94 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.7 130 3.00 Direct Entry, PIPE FLOW
1.6 180 Total
Subcatchment 5S: IMPERVIOUS
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment 6S: POROUS
Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.190 39 >75% Grass cover, Good, HSG A
0.190 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.3 90 0.0270 0.13 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Paved Kv= 20.3 fps
1.1 160 0.0150 2.49
12.4 250 Total
Subcatchment 6S: POROUS
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 8S: PROP WAREHOUSE BLDG
Runoff = 1.48 cfs @ 12.10 hrs, Volume= 0.112 af, Depth> 2.92" Routed to Pond 9P : SSIB #3 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.460 98 Roofs, HSG A
0.460 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.5 100 0.0100 1.08 Sheet Flow,
0.3 40 0.0100 2.03 Smooth surfaces n= 0.011 P2= 3.42"
0.8 140 3.00 Shallow Concentrated Flow, Paved Kv= 20.3 fps
Direct Entry, PIPE FLOW
2.6 280 Total
Subcatchment 8S: PROP WAREHOUSE BLDG
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 12
Summary for Subcatchment 10S: BY-PASS POROUS
Runoff = 0.00 cfs @ 20.00 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac)CNDescription
0.06039>75% Grass cover, Good, HSG A
0.060100.00% Pervious Area
Tc (min)Length (feet)Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.0Direct Entry,
Subcatchment 10S: BY-PASS POROUS
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 11S: BY-PASS IMPERVIOUS
Runoff = 0.24 cfs @ 12.09 hrs, Volume= Routed to Reach 10 : COMPOSITE 0.017 af, Depth> 2.92"
0.017 af, Depth> 2.92"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2 YEAR Rainfall=3.42"
Area (ac) CN Description
0.070 98 Paved parking, HSG A
0.070 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
Direct Entry,
Subcatchment 11S: BY-PASS IMPERVIOUS
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 14
Summary for Reach 10: COMPOSITE
Inflow Area = 2.120 ac, 71.70% Impervious, Inflow Depth > 2.05" for 2 YEAR event Inflow = 2.25 cfs @ 12.18 hrs, Volume= 0.362 af Outflow = 2.25 cfs @ 12.18 hrs, Volume= 0.362 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 10: COMPOSITE
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 15
Summary for Pond 3P: SSIB #1 SURFACE BASIN
Inflow Area =1.070 ac, 67.29% Impervious, Inflow Depth > 1.96" for 2 YEAR event
Inflow =1.36 cfs @ 12.22 hrs, Volume= 0.175 af
Outflow =0.87 cfs @ 12.51 hrs, Volume= 0.171 af, Atten= 36%, Lag= 16.9 min
Discarded =0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Primary =0.87 cfs @ 12.51 hrs, Volume= 0.171 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Starting Elev= 111.50' Surf.Area= 2,825 sf Storage= 3,544 cf Peak Elev= 111.97' @ 12.51 hrs Surf.Area= 3,177 sf Storage= 4,951 cf (1,408 cf above start)
Plug-Flow detention time= 220.0 min calculated for 0.089 af (51% of inflow) Center-of-Mass det. time= 28.4 min (777.9 - 749.5 )
Center-of-Mass det. time= 28.4 min (777.9 - 749.5)
VolumeInvertAvail.StorageStorage Description
#1110.00'12,950 cfCustom Stage Data (Prismatic)Listed below (Recalc)
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
110.002,00000
111.002,4502,2252,225
112.003,2002,8255,050
113.004,0003,6008,650
114.004,6004,30012,950
DeviceRoutingInvertOutlet Devices
#1Discarded110.00'1.000 in/hr Exfiltration X 0.00 over Surface area Conductivity to Groundwater Elevation = 106.00'
#2Primary111.50'12.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
#3Primary113.00'24.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.00 cfs @ 5.00 hrs HW=111.50' (Free Discharge)
Discarded OutFlow Max=0.00 cfs @ 5.00 hrs HW=1111.50' (Free Discharge) 1=Exfiltration (Controls 0.00 cfs)
Primary OutFlow Max=0.87 cfs @ 12.51 hrs HW=111.97' (Free Discharge) 2=Orifice/Grate (Orifice Controls 0.87 cfs @ 2.61 fps) 3=Orifice/Grate (Controls 0.00 cfs)
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 16
Pond 3P: SSIB #1 SURFACE BASIN
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 17
Summary for Pond 8P: SSIB #2 UNDERGROUND
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 1.71" for 2 YEAR event
Outflow = 0.93 cfs @ 12.08 hrs, Volume= 0.066 af
Discarded = 0.44 cfs @ 12.18 hrs, Volume= 0.064 af, Atten= 53%, Lag= 5.8 min
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Starting Elev= 109.00' Surf.Area= 0.064 ac Storage= 0.052 af
Peak Elev= 109.35' @ 12.18 hrs Surf.Area= 0.064 ac Storage= 0.068 af (0.016 af above start)
Plug-Flow detention time= 491.1 min calculated for 0.011 af (17% of inflow)
Plug-Flow detention time= 491.1 min calculated for 0.011 af (17% of inflow) Center-of-Mass det. time= 34.4 min (770.5 - 736.1)
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95'W x 66.33'L x 3.00'H Field A 0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration X 0.00 over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.00 cfs @ 5.00 hrsHW=109.00' (Free Discharge)
1=Exfiltration ( Controls 0.00 cfs)
Primary OutFlowMax=0.44 cfs @ 12.18 hrsHW=109.35' (Free Discharge)
2=Orifice/Grate (Orifice Controls 0.44 cfs @ 1.96 fps)
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 18
Pond 8P: SSIB #2 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 12 Rows x 28.0" Wide + 13.4" Spacing x 11 + 10.0" Side Stone x 2 = 41.95' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 36 Chambers x 62.0 cf + 40.28' Header x 3.10 sf x 2 = 2,481.8 cf Chamber Storage 36 Chambers x 78.4 cf + 40.28' Header x 3.92 sf x 2 = 3,137.9 cf Displacement 8,348.3 cf Field - 3,137.9 cf Chambers = 5,210.4 cf Stone x 40.0% Voids = 2,084.2 cf Stone Storage Chamber Storage + Stone Storage = 4,565.9 cf = 0.105 af Overall Storage Efficiency = 54.7% Overall System Size = 66.33' x 41.95' x 3.00'
36 Chambers 309.2 cy Field 193.0 cy Stone
010101
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 19
Pond 8P: SSIB #2 UNDERGROUND
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 20
Summary for Pond 9P: SSIB #3 UNDERGROUND
Inflow Area =0.460 ac,100.00% Impervious, Inflow Depth > 2.92" for 2 YEAR event
Inflow =1.48 cfs @ 12.10 hrs, Volume= 0.112 af
Outflow =1.09 cfs @ 12.16 hrs, Volume= 0.110 af, Atten= 27%, Lag= 4.0 min
Discarded =0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Primary =1.09 cfs @ 12.16 hrs, Volume= 0.110 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Starting Elev= 113.00' Surf.Area= 0.085 ac Storage= 0.111 af Peak Elev= 113.49' @ 12.16 hrs Surf.Area= 0.085 ac Storage= 0.129 af (0.018 af above start)
Plug-Flow detention time = (not calculated: initial storage exceeds outflow) Center-of-Mass det. time = 22.4 min (759.6 - 737.2)
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A
0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 Inside #1 Inside = 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside = 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration X 0.00 over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.00 cfs @ 5.00 hrsHW=113.00' (Free Discharge)
1=Exfiltration ( Controls 0.00 cfs)
Primary OutFlowMax=1.07 cfs @ 12.16 hrsHW=113.48' (Free Discharge)
2=Orifice/Grate (Orifice Controls 1.07 cfs @ 2.23 fps)
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 21
Pond 9P: SSIB #3 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 16 Rows x 28.0" Wide + 13.4" Spacing x 15 + 10.0" Side Stone x 2 = 55.75' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 48 Chambers x 62.0 cf + 54.08' Header x 3.10 sf x 2 = 3,311.3 cf Chamber Storage 48 Chambers x 78.4 cf + 54.08' Header x 3.92 sf x 2 = 4,186.8 cf Displacement 11,094.6 cf Field - 4,186.8 cf Chambers = 6,907.8 cf Stone x 40.0% Voids = 2,763.1 cf Stone Storage Chamber Storage + Stone Storage = 6,074.4 cf = 0.139 af Overall Storage Efficiency = 54.8% Overall System Size = 66.33' x 55.75' x 3.00'
48 Chambers 410.9 cy Field 255.8 cy Stone
101010
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OCSCD NOAA 24-hr D 2 YEAR Rainfall=3.42" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 22
Pond 9P: SSIB #3 UNDERGROUND
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Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1S: POROUS
Subcatchment1S: POROUS Runoff Area=0.350 ac 0.00% Impervious Runoff Depth>0.21" Flow Length=310' Tc=12.9 min CN=39 Runoff=0.02 cfs 0.006 af
Subcatchment2S: IMPERVIOUS
Subcatchment2S: IMPERVIOUS Runoff Area=0.720 ac 100.00% Impervious Runoff Depth>4.66" Flow Length=310' Tc=13.1 min CN=98 Runoff=2.16 cfs 0.280 af
Subcatchment5S: IMPERVIOUS Runoff Area=0.270 ac 100.00% Impervious Runoff Depth>4.66" Flow Length=180' Slope=0.0100'/' Tc=1.6 min CN=98 Runoff=1.48 cfs 0.105 af
Runoff Area=0.190 ac 0.00% Impervious Runoff Depth>0.22"
Subcatchment6S: POROUS
Flow Length=250' Tc=12.4 min CN=39 Runoff=0.01 cfs 0.003 af
Subcatchment8S: PROP WAREHOUSE Runoff Area=0.460 ac 100.00% Impervious Runoff Depth>4.66" Flow Length=280' Slope=0.0100'/' Tc=2.6 min CN=98 Runoff=2.35 cfs 0.179 af
Runoff Area=0.060 ac 0.00% Impervious Runoff Depth>0.22" Tc=2.0 min CN=39 Runoff=0.00 cfs 0.001 af
Subcatchment10S: BY-PASS POROUS
Runoff Area=0.070 ac 100.00% Impervious Runoff Depth>4.66" Tc=2.0 min CN=98 Runoff=0.37 cfs 0.027 af
Subcatchment11S: BY-PASS
Inflow=3.32 cfs 0.591 af
Outflow=3.32 cfs 0.591 af
Reach 10: COMPOSITE
Pond 3P: SSIB #1 SURFACE BASIN Peak Elev= $ 112.25' $ Storage= 5, 884 cf Inflow= $ 2.16 $ cfs 0.286 af Discarded= $ 0.00 $ cfs 0.000 af Primary= $ 1.22 $ cfs 0.281 af Outflow= $ 1.22 $ cfs 0.281 af
Pond 8P: SSIB #2 UNDERGROUND Peak Elev=109.53' Storage=0.076 af Inflow=1.48 cfs 0.108 af
Discarded=0.00 cfs 0.000 af Primary=0.64 cfs 0.106 af Outflow=0.64 cfs 0.106 af
Pond 9P: SSIB #3 UNDERGROUND Peak Elev=113.70' Storage=0.136 af Inflow=2.35 cfs 0.179 af Discarded=0.00 cfs 0.000 af Primary=1.59 cfs 0.176 af Outflow=1.59 cfs 0.176 af
Total Runoff Area = 2.120 ac Runoff Volume = 0.601 af Average Runoff Depth = 3.40" 28.30% Pervious = 0.600 ac 71.70% Impervious = 1.520 ac
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Summary for Subcatchment 1S: POROUS
Runoff = 0.02 cfs @ 13.03 hrs, Volume= 0.006 af, Depth> 0.21" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.350 39 >75% Grass cover, Good, HSG A
0.350 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.3 50 0.0350 2.81
0.9 160 3.00 Direct Entry, PIPE FLOW
12.9 310 Total
Subcatchment 1S: POROUS
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Summary for Subcatchment 2S: IMPERVIOUS
Runoff = 2.16 cfs @ 12.22 hrs, Volume= 0.280 af, Depth> 4.66" Routed to Pond 3P : SSIB #1 SURFACE BASIN
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.720 98 Paved parking, HSG A
0.720 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.7 100 0.0300 0.14 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42" Shallow Concentrated Flow, Grassed Waterway Kv= 15.0 fps
0.5 50 0.0110 1.57
0.9 160 3.00 Direct Entry, PIPE FLOW
13.1 310 Total
Subcatchment 2S: IMPERVIOUS
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Summary for Subcatchment 5S: IMPERVIOUS
Runoff = 1.48 cfs @ 12.08 hrs, Volume= Routed to Pond 8P : SSIB #2 UNDERGROUND 0.105 af, Depth> 4.66"
0.105 af, Depth> 4.66"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.270 98 Roofs, HSG A
0.270 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 50 0.0100 0.94 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.7 130 3.00 Direct Entry, PIPE FLOW
1.6 180 Total
Subcatchment 5S: IMPERVIOUS
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Summary for Subcatchment 6S: POROUS
Runoff = 0.01 cfs @ 13.01 hrs, Volume= 0.003 af, Depth> 0.22" Routed to Pond 8P : SSIB #2 UNDERGROUND
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.190 39 >75% Grass cover, Good, HSG A
0.190 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
11.3 90 0.0270 0.13 Sheet Flow, Grass: Dense n= 0.240 P2= 3.42"
1.1 160 0.0150 2.49 Shallow Concentrated Flow, Paved Kv= 20.3 fps
12.4 250 Total
Subcatchment 6S: POROUS
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Summary for Subcatchment 8S: PROP WAREHOUSE BLDG
Runoff = 2.35 cfs @ 12.10 hrs, Volume= Routed to Pond 9P : SSIB #3 UNDERGROUND 0.179 af, Depth> 4.66"
0.179 af, Depth> 4.66"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.460 98 Roofs, HSG A
0.460 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.5 100 0.0100 1.08 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.42"
0.3 40 0.0100 2.03 Shallow Concentrated Flow, Paved Kv= 20.3 fps
0.8 140 3.00 Direct Entry, PIPE FLOW
2.6 280 Total
Subcatchment 8S: PROP WAREHOUSE BLDG
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Summary for Subcatchment 10S: BY-PASS POROUS
Runoff = 0.00 cfs @ 12.50 hrs, Volume= 0.001 af, Depth> 0.22" Routed to Reach 10 : COMPOSITE
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac)CNDescription
0.06039>75% Grass cover, Good, HSG A
0.060100.00% Pervious Area
Tc (min)Length (feet)Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.0Direct Entry,
Subcatchment 10S: BY-PASS POROUS
☐ Runoff
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Summary for Subcatchment 11S: BY-PASS IMPERVIOUS
Runoff = 0.37 cfs @ 12.09 hrs, Volume= Routed to Reach 10 : COMPOSITE 0.027 af, Depth> 4.66"
0.027 af, Depth> 4.66"
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10 YEAR Rainfall=5.38"
Area (ac) CN Description
0.070 98 Paved parking, HSG A
0.070 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
Direct Entry,
Subcatchment 11S: BY-PASS IMPERVIOUS
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OCSCD NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 31
Summary for Reach 10: COMPOSITE
Inflow Area = 2.120 ac, 71.70% Impervious, Inflow Depth > 3.34" for 10 YEAR event Inflow = 3.32 cfs @ 12.18 hrs, Volume= 0.591 af Outflow = 3.32 cfs @ 12.18 hrs, Volume= 0.591 af, Atten=0%, Lag=0.0 min
Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Reach 10: COMPOSITE
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Summary for Pond 3P: SSIB #1 SURFACE BASIN
nflow Area = 1.070 ac, 67.29% Impervious, Inflow Depth > 3.21" for 10 YEAR event
nflow = 2.16 cfs @ 12.22 hrs, Volume= 0.286 af
Outflow = 1.22 cfs @ 12.58 hrs, Volume= 0.281 af, Atten= 43%, Lag= 21.1 min
Discarded = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Primary = 1.22 cfs @ 12.58 hrs, Volume= 0.281 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Starting Elev= 111.50' Surf.Area= 2,825 sf Storage= 3,544 cf Peak Elev= 112.25' @ 12.58 hrs Surf.Area= 3,402 sf Storage= 5,884 cf (2,340 cf above start)
Plug-Flow detention time= 164.2 min calculated for 0.199 af (69% of inflow)
Plug-Flow detention time = 164.2 min calculated for 0.199 af (69% of inflow) Center-of-Mass det. time = 27.0 min (777.3 - 750.3)
VolumeInvertAvail.StorageStorage Description
#1110.00'12,950 cfCustom Stage Data (Prismatic)Listed below (Recalc)
Elevation (feet)Surf.Area (sq-ft)Inc.Store (cubic-feet)Cum.Store (cubic-feet)
110.002,00000
111.002,4502,2252,225
112.003,2002,8255,050
113.004,0003,6008,650
114.004,6004,30012,950
DeviceRoutingInvertOutlet Devices
#1Discarded110.00'1.000 in/hr Exfiltration X 0.00 over Surface area Conductivity to Groundwater Elevation = 106.00'
#2Primary111.50'12.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
#3Primary113.00'24.0" x 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlow Max=0.00 cfs @ 5.00 hrs HW=111.50' (Free Discharge)
Discarded OutFlow Max=0.00 cfs @ 5.00 hrs HW=1111.50' (Free Discharge) 1=Exfiltration (Controls 0.00 cfs)
Primary OutFlow Max=1.22 cfs @ 12.58 hrs HW=112.25' (Free Discharge) 2=Orifice/Grate (Orifice Controls 1.22 cfs @ 3.67 fps) 3=Orifice/Grate (Controls 0.00 cfs)
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Pond 3P: SSIB #1 SURFACE BASIN
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Summary for Pond 8P: SSIB #2 UNDERGROUND
Inflow Area = 0.460 ac, 58.70% Impervious, Inflow Depth > 2.83" for 10 YEAR event
Inflow = 1.48 cfs @ 12.08 hrs, Volume= 0.108 af
Outflow = 0.64 cfs @ 12.19 hrs, Volume= 0.106 af, Atten= 56%, Lag= 6.5 min
Discarded = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Primary = 0.64 cfs @ 12.19 hrs, Volume= 0.106 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Starting Elev= 109.00' Surf.Area= 0.064 ac Storage= 0.052 af Peak Elev= 109.53' @ 12.19 hrs Surf.Area= 0.064 ac Storage= 0.076 af (0.024 af above start)
Plug-Flow detention time= 236.1 min calculated for 0.053 af (49% of inflow)
Plug-Flow detention time= 236.1 min calculated for 0.053 af (49% of inflow) Center-of-Mass det. time= 29.7 min (769.0 - 739.2)
VolumeInvertAvail.StorageStorage Description
#1A107.50'0.048 af41.95'W x 66.33'L x 3.00'H Field A 0.192 af Overall - 0.072 af Embedded = 0.120 af x 40.0% Voids
#2A107.83'0.057 afADS N-12 24" x 36 Inside #1 Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 36 Chambers in 12 Rows 40.28' Header x 3.10 sf x 2 = 249.8 cf Inside
0.105 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded107.50'1.000 in/hr Exfiltration X 0.00 over Surface area Conductivity to Groundwater Elevation = 105.00'
#2Primary109.00'8.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.00 cfs @ 5.00 hrsHW=109.00' (Free Discharge)
1=Exfiltration ( Controls 0.00 cfs)
Primary OutFlowMax=0.64 cfs @ 12.19 hrsHW=109.53' (Free Discharge)
2=Orifice/Grate (Orifice Controls 0.64 cfs @ 2.89 fps)
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Pond 8P: SSIB #2 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 12 Rows x 28.0" Wide + 13.4" Spacing x 11 + 10.0" Side Stone x 2 = 41.95' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 36 Chambers x 62.0 cf + 40.28' Header x 3.10 sf x 2 = 2,481.8 cf Chamber Storage 36 Chambers x 78.4 cf + 40.28' Header x 3.92 sf x 2 = 3,137.9 cf Displacement 8,348.3 cf Field - 3,137.9 cf Chambers = 5,210.4 cf Stone x 40.0% Voids = 2,084.2 cf Stone Storage Chamber Storage + Stone Storage = 4,565.9 cf = 0.105 af Overall Storage Efficiency = 54.7% Overall System Size = 66.33' x 41.95' x 3.00'
36 Chambers 309.2 cy Field 193.0 cy Stone
0101010101010101010
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Pond 8P: SSIB #2 UNDERGROUND
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OCSCD NOAA 24-hr D 10 YEAR Rainfall=5.38" Prepared by Professional Design Services Printed 12/31/2025 HydroCAD® 10.20-6a s/n 02223 © 2024 HydroCAD Software Solutions LLC Page 37
Summary for Pond 9P: SSIB #3 UNDERGROUND
Inflow Area = 0.460 ac,100.00% Impervious, Inflow Depth > 4.66" for 10 YEAR event
Inflow = 2.35 cfs @ 12.10 hrs, Volume= 0.179 af
Outflow = 1.59 cfs @ 12.17 hrs, Volume= 0.176 af, Atten= 32%, Lag= 4.5 min
Discarded = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Primary = 1.59 cfs @ 12.17 hrs, Volume= 0.176 af
Routed to Reach 10 : COMPOSITE
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Starting Elev= 113.00' Surf.Area= 0.085 ac Storage= 0.111 af Peak Elev= 113.70' @ 12.17 hrs Surf.Area= 0.085 ac Storage= 0.136 af (0.025 af above start)
Plug-Flow detention time= 288.6 min calculated for 0.065 af (36% of inflow)
Plug-Flow detention time= 288.6 min calculated for 0.065 af (36% of inflow) Center-of-Mass det. time= 18.8 min (753.0 - 734.2)
VolumeInvertAvail.StorageStorage Description
#1A110.80'0.063 af55.75'W x 66.33'L x 3.00'H Field A 0.255 af Overall - 0.096 af Embedded = 0.159 af x 40.0% Voids
#2A111.13'0.076 afADS N-12 24" x 48 Inside #1 Inside = 23.8"W x 23.8"H => 3.10 sf x 20.00'L = 62.0 cf Outside = 28.0"W x 28.0"H => 3.92 sf x 20.00'L = 78.4 cf 48 Chambers in 16 Rows 54.08' Header x 3.10 sf x 2 = 335.3 cf Inside
0.139 af Total Available Storage
Storage Group A created with Chamber Wizard
DeviceRoutingInvertOutlet Devices
#1Discarded110.80'1.000 in/hr Exfiltration X 0.00 over Surface area Conductivity to Groundwater Elevation = 108.00'
#2Primary113.00'12.0" W x 6.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads
Discarded OutFlowMax=0.00 cfs @ 5.00 hrsHW=113.00' (Free Discharge)
1=Exfiltration ( Controls 0.00 cfs)
Primary OutFlowMax=1.57 cfs @ 12.17 hrsHW=113.69' (Free Discharge)
2=Orifice/Grate (Orifice Controls 1.57 cfs @ 3.15 fps)
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Pond 9P: SSIB #3 UNDERGROUND - Chamber Wizard Field A
Chamber Model = ADS N-12 24" (ADS N-12® Pipe) Inside= 23.8"W x 23.8"H => 3.10 sf x 20.00"L = 62.0 cf Outside= 28.0"W x 28.0"H => 3.92 sf x 20.00"L = 78.4 cf 28.0" Wide + 13.4" Spacing = 41.4" C-C Row Spacing 3 Chambers/Row x 20.00' Long +2.33' Header x 2 = 64.67' Row Length +10.0" End Stone x 2 = 66.33' Base Length 16 Rows x 28.0" Wide + 13.4" Spacing x 15 + 10.0" Side Stone x 2 = 55.75' Base Width 4.0" Stone Base + 28.0" Chamber Height + 4.0" Stone Cover = 3.00' Field Height 48 Chambers x 62.0 cf + 54.08' Header x 3.10 sf x 2 = 3,311.3 cf Chamber Storage 48 Chambers x 78.4 cf + 54.08' Header x 3.92 sf x 2 = 4,186.8 cf Displacement 11,094.6 cf Field - 4,186.8 cf Chambers = 6,907.8 cf Stone x 40.0% Voids = 2,763.1 cf Stone Storage Chamber Storage + Stone Storage = 6,074.4 cf = 0.139 af Overall Storage Efficiency = 54.8% Overall System Size = 66.33' x 55.75' x 3.00'
48 Chambers 410.9 cy Field 255.8 cy Stone
101010
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Pond 9P: SSIB #3 UNDERGROUND
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APPENDIX E GROUNDWATER MOUNDING
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SSIB #1 SURFACE BASIN
Input Values
Input Values
1.00 R
0.150 Sy
Specific yield, Sy (dimensionless)
20.00 Kh
35.000 x
Horizontal hydraulic conductivity (in/hr)
15.000 y
20.00 Kh Kh = 5xRecharge Rate (R) in the costal plan; Kh=R outside the coastal plan
24.00 t
35.000 x 1/2 length of basin (x direction, in feet)
10.00 h(0)
15.000 y 1/2 width of basin (y direction, in feet)
12.337 h(max)
24.00 t Duration of infiltration period (hours)
10.00 hi(0) Initial thickness of saturated zone (feet)
2.337 Δ h(max)
12.337 h(max) Maximum thickness of saturated zone (beneath center of basin at end of infiltration period)
Ground-water Distance from center of basin in x
2.337 Δ h(max) Maximum groundwater mounding (beneath center of basin at end of infiltration period)
1.00 R Recharge rate (permeability rate) (in/hr)
0.150 Sy default value is 0.15; max value is 0.2 provided that a lab test data is submitted
Mounding, in feet direction, in feet
Distance from
2.337 0
Disclaimer
This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater mounding beneath hypothetical stormwater infiltration basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions.
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SSIB #3 UNDERGROUND
Input Values
1.00 R
0.150 Sy
20.00 Kh
28.000 y
12.00 t
10.00 hi(0)
h(max)
2.756 Δ h(max)
Maximum thickness of saturated zone (beneath center of basin at end of infiltration period)
33.000 x
Maximum groundwater mounding (beneath center of basin at end of infiltration period)
Ground-water center of basin in x
Mounding, in feet direction, in feet
0 0
2.756 0
2.681 10
2.446 20
2.018 30
1.451 40
1.011 50
0.690 60
0.461 70
0.302 80
0.194 90
Disclaimer
This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater Mounding Beneath Hypothetical Stormwater Infiltration Basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions.
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Input Values
1.00 R Recharge rate (permeability rate) (in/hr)
0.150 Sy Specific yield, Sy (dimensionless)
20.00 Kh default value is 0.15; max value is 0.2 provided that a lab test data is submitted
33.000 x Horizontal hydraulic conductivity (in/hr)
21.000 y Kh = 5xRecharge Rate (R) in the costal plan; Kh=R outside the coastal plan
20.00 t 1/2 length of basin (x direction, in feet)
10.00 hi(0) 1/2 width of basin (y direction, in feet)
12.745 h(max) Duration of infiltration period (hours)
2.745 Δ h(max) Initial thickness of saturated zone (feet)
Ground-water Distance from center of basin in x Maximum thickness of saturated zone (beneath center of basin at end of infiltration period)
Mounding, in feet direction, in feet Maximum groundwater mounding (beneath center of basin at end of infiltration period)
2.745 0 Groundwater Mounding, in feet
2.680 10 Groundwater Mounding, in feet
2.472 20 Groundwater Mounding, in feet
2.086 30 Groundwater Mounding, in feet
1.569 40 Groundwater Mounding, in feet
1.166 50 Groundwater Mounding, in feet
0.864 60 Groundwater Mounding, in feet
0.636 70 Groundwater Mounding, in feet
0.464 80 Groundwater Mounding, in feet
0.335 90 Groundwater Mounding, in feet
Disclaimer
This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater mounding beneath hypothetical stormwater infiltration basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions.