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Stormwater Management, Groundwater Recharge and Water Quality Analysis
For
1980 Swarthmore LLC
30 S. Hope Chapel Road (CR 547)
Block 20901, Lot 15
Township of Jackson
Ocean County, New Jersey
Prepared by:
D DYNAMIC ENGINEERING
5 Greentree Centre, Suite 406
Marlton, NJ 08053
(732) 974-0198
Rodman R. Ritchie, PE, PP
NJ Professional Engineer License #43547
August 2023
Last Revised February 2026
DEC #3342-99-007
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TABLE OF CONTENTS
Page No.
SITE DESCRIPTION AND PROJECT OVERVIEW ..... - 1
DESIGN OVERVIEW ..... - 1
EXISTING DRAINAGE CONDITIONS ..... - 3
PROPOSED DRAINAGE CONDITIONS ..... - 4
STORMWATER MANAGEMENT SYSTEM DESIGN ..... - 6
GREEN INFRASTRUCTURE COMPLIANCE ..... - 6
WATER QUALITY COMPLIANCE ..... - 8
GROUNDWATER RECHARGE COMPLIANCE ..... - 8
GROUNDWATER MOUNDING ..... - 8
PINELANDS NITROGEN REMOVAL REQUIREMENT ..... - 9
STORM SEWER DESIGN ..... - 9
SOIL EROSION AND SEDIMENT CONTROL COMPLIANCE ..... - 9
CONCLUSION ..... - 12
APPENDIX
NRCS Web Soil Survey
Hydrograph Summary Reports – Existing & Proposed Conditions 2, 10, & 100-year
Hydrograph Summary Reports – Existing & Proposed Water Quality Storm
Hydrograph Comparison – Study Area Road Undetained 2, 10 & 100-year
Stormwater Collection System Calculations (Pipe Sizing)
Conduit Outlet Protection Calculations
Groundwater Recharge Calculation
Groundwater Mounding Calculation
Basin Drain Time Calculations
Offsite Stability Failure Analysis
Report of Geotechnical & Stormwater Basin Area Investigation, prepared by Dynamic Earth, LLC
Drainage Area Maps
Nitrogen Removal Exhibit
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1. SITE DESCRIPTION AND PROJECT OVERVIEW
The subject site is located at 30 South Hope Chapel Road (C.R. 547) in the Township of Jackson, Ocean County, New Jersey. The site is identified as Block 20901, Lot 15 on the Township of Jackson Tax Map Sheet #209. The subject site is currently developed with one 2,164 SF single family home, three one-story garages and a contractor's yard. The property is bounded to the north by residential uses with wooded areas, commercial uses and East Veterans Highway beyond, to the south by Garden Street with residential uses beyond, to the east by S. Hope Chapel (CR 547) with commercial uses beyond, and to the west by residential uses with wooded areas beyond.
The proposed project consists of the development of a 3-story office building. The office building will consist of a total footprint of 4,937 SF, and a total square footage of 14,979 SF. The proposed project will also include associated site improvements including parking areas, landscaping, lighting, stormwater management facilities, and utilities.
2. DESIGN OVERVIEW
This report has been prepared to define and analyze the stormwater drainage conditions that would occur as a result of the development of the subject site. Based upon the fact that the proposed development will result in more than 1 acre of land disturbance, increase in impervious coverage by more than 1/4 acre, and increase motor vehicle surfaces by more than 1/4 acre, this project is classified as a “major development” as defined in NJAC 7:8 and NJAC 7:50. Therefore, the proposed development has been designed to meet the stormwater water runoff quantity, quality, and groundwater recharge standards, as set forth by the Township of Jackson Land Use Ordinance, NJAC 7:8 and NJAC 7:50.
The following documents and data were used in the support of the design of the project.
A survey entitled “Boundary, Location & Topographic Survey” prepared by Dynamic Survey, LLC, dated October 22, 2021;
Site Plans entitled “Preliminary and Final Site Plan” prepared by Dynamic Engineering Consultants, PC dated August 25, 2023;
Geotechnical Report entitled “Report of Geotechnical & Stormwater Basin Area Investigation Report” prepared by Dynamic Earth, LLC dated June 24, 2022;
NRCS Web Soil Survey
NJDEP Stormwater Management Best Management Practices Manual
NJDEP New Jersey Pinelands Comprehensive Management Plan
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The hydrology for the site was calculated using the NRCS Runoff Equation and Dimensionless Unit Hydrograph as noted in Part 630, Hydrology National Engineering Handbook. The following particular references were used:
Curve Numbers were established via Chapter 9 – Hydrological Soil-Cover Complexes
Time of Concentration were calculated in accordance with Chapter 15
Rainfall Distributions are based on NOAA Type D rainfall distribution
The Delmarva Unit Hydrograph was utilized
The rainfall depths are based on Ocean County NOAA Atlas 14 Data as noted below:
| Return Period | NOAA Atlas 14 Rainfall Depth (inches) |
|---|---|
| 2 Year Storm - Current | 3.42 |
| 2 Year Storm - Projected | 4.04 |
| 10 Year Storm - Current | 5.38 |
| 10 Year Storm - Projected | 6.34 |
| 100 Year Storm - Current | 9.48 |
| 100 Year Storm - Projected | 11.41 |
Based upon the Ocean County Soil Survey, the soil types native to the site include:
| Soil Type | Soil Type Name | Hydrologic Soil Group |
|---|---|---|
| DofgB | Downer gravelly sand loam, gravelly substratum, 2 to 5 percent slopes | A |
Based on the methodology and data noted above a hydrologic evaluation of the NJDEP Water Quality, 2-, 10-, and 100-year storm event was prepared.
This report will address compliance with the following standards:
Groundwater Recharge Standards (NJAC 7:50-56.84(a)6.iv(1))
Stormwater Runoff Quality Standards (NJAC 7:8-5.5 and NJAC 7:50-56.84(a)6.iv(6))
Stormwater Runoff Quantity Standards (NJAC 7:8-5.6 and NJAC 7:50-56.84(a)6))
Calculation of Stormwater Runoff (NJAC 7:8-5.7 and NJAC 7:50-56.84(a)6)
Green Infrastructure Standards (NJAC 7:8-5.3 and NJAC 7:50-56.84(a)6)
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3. EXISTING DRAINAGE CONDITIONS
The area to be analyzed consists of approximately 1.17 acres and is comprised of mostly grassy area, with a residential building, garages, and asphalt paving. Currently, the stormwater runoff generated by the existing site drains to the western and eastern portions of the site via overland flow. Due to commercial development that occurred since 1981 without application to the Pinelands Commission the subject site has been evaluated using an Historical Area Map from 1972 as depicted in the Existing Drainage Area Map included in the Appendix of this report.
Point of Analysis #1 – Existing Study Area West
Existing Study Area West: This area consists of 1.020 acres and is comprised of mostly grassy area, a one-story house, two (2) garages, and asphalt paving. Under existing conditions, the stormwater runoff generated by the existing site drains to the western portion of the site via overland flow.
Existing Conditions Input Summary Table
| Drainage Area Name | Drainage Area (acres) | Time of Concentration (minutes) | Curve Number (CN) |
|---|---|---|---|
| Ex. Study Area West (Perv) | 0.93 | 8.8 | 39 |
| Ex. Study Area West (Imp) | 0.09 | 2.0 | 98 |
| Ex. Total | 1.02 | - | - |
Existing Conditions Flow Summary Table
| Current Rainfall Conditions | Projected Rainfall Conditions | |||||
| Drainage Area Name | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) |
|---|---|---|---|---|---|---|
| Ex. Study Area West Total | 0.19 | 0.30 | 1.51 | 0.23 | 0.45 | 2.37 |
Point of Analysis #2 - Existing Study Area Road
Existing Study Area Road: This area consists of 0.150 acres and is comprised of mostly grassy area, concrete, and asphalt paving as well as a portion of the existing South Hope Chapel Road (C.R. 547) right-of-way along the subject property frontage. Under existing conditions, the stormwater runoff generated by the existing site drains to the eastern portion of the site via overland flow.
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Existing Conditions Input Summary Table
| Drainage Area Name | Drainage Area (acres) | Time of Concentration (minutes) | Curve Number (CN) |
|---|---|---|---|
| Ex. Study Area Road (Perv) | 0.12 | 1.0 | 39 |
| Ex. Study Area Road (Imp) | 0.03 | 1.0 | 98 |
| Ex. Total | 0.15 | - | - |
Existing Conditions Flow Summary Table
| Current Rainfall Conditions | Projected Rainfall Conditions | |||||
| Drainage Area Name | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) |
|---|---|---|---|---|---|---|
| Ex. Study Area Road Total | 0.06 | 0.10 | 0.30 | 0.08 | 0.13 | 0.44 |
4. PROPOSED DRAINAGE CONDITIONS
The proposed development will incorporate one (1) underground infiltration basin and one (1) manufactured treatment device (MTD) into the layout of the facility for stormwater management. The basin is designed to detain, treat, and infiltrate a portion of stormwater runoff generated by the development in order to meet the stormwater management requirements. The proposed site conditions have been evaluated using the following drainage sub-watershed areas as depicted on the Proposed Drainage Area Map included in the Appendix of this report.
Point of Analysis #1 – Study Area West
Study Area WQ MTD A-110: This area consists of 0.63 acres in the central portion of the site which includes open space and impervious areas. Under proposed conditions, stormwater runoff generated by this area flows to proposed inlets via overland flow and through the pipe conveyance system to the proposed MTD and underground infiltration basin. Stormwater from the basin is released through an outlet control structure to the proposed stormwater conveyance system and discharged via the proposed scour hole.
Study Area Roof: This area consists of 0.11 acres in the central portion of the site which includes only the roof of the proposed building. Under proposed conditions, stormwater runoff generated by this area flows to proposed stormwater management infrastructure via channel flow within the proposed roof leader the proposed pipe conveyance system to the proposed underground infiltration basin. Stormwater from the basin
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is released through an outlet control structure to the proposed stormwater conveyance system and discharged via the proposed scour hole.
Study Area West Undetained: The area consists of 0.31 acres in the northern, southern, and western portions of the site which includes open, grassy areas. Under proposed conditions, stormwater runoff captured in this area will run offsite via overland flow.
Proposed Conditions Input Summary Table
| Drainage Area Name | Drainage Area (acres) | Time of Concentration (minutes) | Curve Number (CN) |
|---|---|---|---|
| Study Area WQ MTD A-110 – Imp. | 0.61 | 1.9 | 98 |
| Study Area WQ MTD A-110 – Perv. | 0.02 | 2.9 | 39 |
| Study Area WQ MTD A-110 – Total | 0.63 | -- | -- |
| Study Area Roof – Imp. | 0.11 | 0.8 | 98 |
| Study Area Roof – Total | 0.11 | -- | -- |
| Study Area West Undetained – Perv. | 0.31 | 2.7 | 39 |
| Study Area West Undetained – Total | 0.31 | -- | -- |
Proposed Conditions Flow Summary Table
| Current Rainfall Data | Projected Rainfall Data | |||||
| Drainage Area Name | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) |
|---|---|---|---|---|---|---|
| Study Area WQ MTD A-110 – Total | 1.30 | 2.05 | 3.65 | 1.54 | 2.42 | 4.41 |
| Study Area Basin A – Total | 1.53 | 2.42 | 4.30 | 1.81 | 2.86 | 5.20 |
| Study Area West – Total | 0.00 | 0.02 | 0.80 | 0.00 | 0.05 | 1.22 |
Point of Analysis #2 – Study Area Road Undetained
Study Area Road Undetained: The area consists of 0.12 acres in the eastern portion of the site which includes open, grassy areas and asphalt pavement. Under proposed conditions, stormwater runoff captured in this area will run offsite via overland flow.
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Proposed Conditions Input Summary Table
| Drainage Area Name | Drainage Area (acres) | Time of Concentration (minutes) | Curve Number (CN) |
|---|---|---|---|
| Study Area Road Undetained – Imp. | 0.04 | 0.4 | 98 |
| Study Area Road Undetained – Perv. | 0.08 | 4.8 | 39 |
| Study Area Road Undetained – Total | 0.12 | -- | -- |
Proposed Conditions Flow Summary Table
| Current Rainfall Data | Projected Rainfall Data | ||||
| Q2 (CFS) | Q10 (CFS) | Q100 (CFS) | Q2 (CFS) | Q10 (CFS) | Q100 (CFS) |
|---|---|---|---|---|---|
| 0.08 | 0.13 | 0.32 | 0.10 | 0.13 | 0.43 |
Study Area Road Undetained – Total
5. STORMWATER MANAGEMENT SYSTEM DESIGN
A summary of each basin's water surface elevation (WSEL) and outflow rated for the Water Quality, 2-, 10-, and 100-year storm event for current conditions are provided below. These WSELs and outflows assume normal operating conditions for each basin. Routing calculations for the basin are included in the Appendix.
Basin A Summary Table
| Storm Event (years) | Water Surface Elevation (ft) | Outflow (CFS) |
|---|---|---|
| 2-Year Current | 117.82 | 0.70 |
| 2- Year Projected | 117.98 | 0.70 |
| 10-Year Current | 118.37 | 0.70 |
| 10- Year Projected | 118.68 | 0.70 |
| 100-Year Current | 119.50 | 1.33 |
| 100- Year Projected | 120.00 | 1.62 |
| WQ Storm | 117.70 | 0.70 |
6. GREEN INFRASTRUCTURE COMPLIANCE
The basin noted above has been designed to comply with the stormwater runoff quantity, quality, and groundwater recharge requirements for the proposed development as applicable. The basin has been designed in accordance with NJAC 7:8, NJAC 7:50 and the New Jersey Stormwater Best Management Practices. The table below summarizes the design considerations for each basin, see the Site Plan details for additional information.
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Small-Scale Infiltration Basins (Table 5-1 – Quantity, Quality, & Recharge)
| Design Criteria | Required | Provided |
|---|---|---|
| Total Drainage Area | -- | Basin A: 0.74 Acres |
| Min. Storage Volume below 1st Orifice (Net Increase of Impervious 10 Year Storm Volume) | Basin A: 0.101 ac-ft | Basin A: 0.392 ac-ft |
| Max. Contributory DA | 2.5 acres | Basin A: 0.787 Acres |
| Max. Drain Time | 72 hours | Basin A: 24.65 hours |
| Separation from SHWT | 2 feet | Basin A: 11.7 feet, additional testing required (SPP-1) |
| Design Permeability Rate | Min. = 0.5 in/hr Max. = 10 in/hr | Basin A: 10 in/hr (SPP-1) |
| Max. Depth of WQ Storm | 2 feet | Basin A: 0.20 ft |
| Pretreatment | 80% TSS Removal BMP upstream of Underground Basin A | Hydro International Up-Flo Filter |
7. WATER QUANTITY CONTROL COMPLIANCE
The site has been designed to meet the flow reduction requirements as noted in NJAC 7:8-5.6(b)3. The points of analysis have been identified on the Drainage Area Maps as previously described. Below is a summary table demonstrating compliance with the flow reduction requirements. Peak Flow Reduction Calculations are included within the appendix of this report.
Point of Analysis #1 (Study Area West)
| Storm Event | Existing Peak Flow (CFS) | Required Reduction | Max. Allowable Peak Flow (CFS) | Proposed Peak Flow (CFS) |
|---|---|---|---|---|
| 2-Year Current | 0.25 | 0.50 | 0.125 | 0.00 |
| 2- Year Projected | 0.23 | 0.50 | 0.115 | 0.00 |
| 10-Year Current | 0.41 | 0.25 | 0.225 | 0.01 |
| 10- Year Projected | 0.45 | 0.25 | 0.338 | 0.04 |
| 100-Year Current | 1.81 | 0.20 | 1.208 | 0.88 |
| 100- Year Projected | 2.37 | 0.20 | 1.896 | 1.27 |
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Point of Analysis #2 (Study Area Road)
The post-construction runoff hydrographs for the current and projected 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. Refer to appendix for hydrograph comparisons of this point of analysis.
8. WATER QUALITY COMPLIANCE
In accordance with NJAC 7:8-5.5, stormwater quality standards are applicable when a major development results in an increase of one-quarter acre or more of regulated motor vehicle surface. The proposed development utilizes the following BMP in order to meet the required 80% TSS removal rate as annual average:
| Green Infrastructure BMP | TSS Removal Rate per BMP Manual |
|---|---|
| Hydro International Up-Flo Filter | 80% |
9. GROUNDWATER RECHARGE COMPLIANCE
The project has been designed to satisfy the groundwater recharge requirements set forth in NJAC 7:50-56.84(a)6.iv(1) by infiltrating the total runoff generated from the net increase in impervious surfaces by a 10-year, 24-hour storm. HydroCAD Stormwater Modeling Software has been utilized to verify satisfaction of the recharge requirement. Groundwater Recharge Calculations are included within the appendix of this report.
| Groundwater Recharge Summary | |
| Pre-Development 10-Year Impervious Volume | 0.046 AC-FT |
|---|---|
| Post-Development 10-Year Impervious Volume | 0.366 AC-FT |
| Net Volume to be Infiltrated | 0.320 AC-FT |
| Volume below Lowest Orifice | 0.392 AC-FT |
10. GROUNDWATER MOUNDING
The proposed underground infiltration basin has been designed to retain and infiltrate the total runoff volume generated from the net increase in impervious surfaces by the 10-year, 24-hour storm, per NJAC 7:50 requirements. The total volume that is required to be retained and infiltrated is 13,939 cubic feet. The volume requirement is met by modeling exfiltration within HydroCAD for the proposed underground infiltration basin. This provides approximately 17,075 cubic feet of water to be infiltrated during the 10-year projected rainfall event. When utilizing the infiltrated volume the maximum mound during the 10-year storm is 8.664 feet. Seasonal High Groundwater was not encountered during the field tests, therefore the termination elevation for SPP-1 (105.8) was used to determine the approximate height of the mound during the 10-year storm. The mound during the 10-year storm could reach a maximum elevation of 114.46 which is 3.04 feet below the
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proposed bottom of basin (elevation 117.50). Therefore, no negative impacts are anticipated. The ground water mounding calculations can be found in the appendix of this report.
11. PINELANDS NITROGEN REMOVAL REQUIREMENT
The project has been designed to satisfy the Nitrogen removal requirements set forth in NJAC 7:50 through the use of an underground basin with a manufactured treatment device. The grading and stormwater conveyance system has been designed to route runoff from motor vehicle surface, landscaped areas and roofs to a proposed underground basin with a MTD to comply with the required nitrogen removal of 53.2%, the proposed Nitrogen removal rate is 59.0%. Further it is noted that the proposed roof and sidewalk areas are not generating nitrogen; therefore 100% nitrogen removal has been provided within those areas. The Pinelands Nitrogen Removal calculations and Exhibit can be found in the Appendix of this report.
12. STORM SEWER DESIGN
The proposed stormwater management collection system has been designed to have hydraulic capacity for the 25-year storm event. The Rational Method was used to determine inflow rates to each structure and Manning's Equation was used to establish pipe capacity. In accordance with the NJDEP BMP Manual Chapter 5, weighted runoff coefficients were computed for each drainage area based on land cover and hydrologic soil group. The time of concentration was calculated for each area. Rainfall intensity was based upon the Trenton Rainfall intensity curve. Supporting calculations and the Inlet Drainage Area Map can be found in the appendix.
13. SOIL EROSION AND SEDIMENT CONTROL COMPLIANCE
The project has been designed to comply with the Standards for Soil Erosion and Sediment Control in New Jersey. Soil erosion control measures such as a stabilized construction entrance, inlet protection and silt fence are shown on the plans. In addition, conduit outlet protection is proposed at the outflow point of the storm sewer system with supporting calculations included in the Appendix of this report. Finally, this project has been designed to satisfy the off-site stability standards set forth in the Standards for Soil Erosion and Sediment Control in New Jersey.
As noted previously, the proposed peak flows meet the necessary requirements set forth in NJAC 7:8-5.6 and NJAC 7:50-56.84(a)6), thereby achieving off-site stability.
Special consideration shall be given to the use of infiltration for peak flow modifications as follows:
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Point Of Discharge Stability Analysis
When infiltration practices are proposed, an alternate analysis (failure analysis) must be provided which ignores infiltration (no dead storage volume available, no static or dynamic infiltration loss rates in the routing calculations, etc.) and demonstrates that no erosion will occur at the point of discharge if infiltration fails to function. Flow rates based solely upon basin inlet and outlet hydraulics must be used in comparison to Table 21-1 (below) to document a stable outlet.
A failure analysis has been provided within the Appendix of this report, which ignores infiltration and demonstrates that no erosion will occur at the point of discharge if infiltration fails to function. To summarize, when disregarding any infiltration and dead storage within the proposed basin the peak outflow for the 25 year storm is 1.06 CFS which complies with the point discharge requirements within the Standards for Soil Erosion and Sediment Control in New Jersey.
Downstream (Off-Site) Stability Analysis
Infiltration may be used to meet peak flow reduction requirements (outlined below) for the purposes of documenting stability of the downstream receiving channel, provided that the complete loss of infiltration function does not result in an increase in peak flow values above the predevelopment levels.
Analysis below the points of discharge to the downstream receiving channel have been provided below.
Point of Discharge - Methods for Achieving Stability
1. Well-defined waterway below the point of discharge:
There is a well-defined waterway (Dove Mill Branch Tributary) below the point of discharge; therefore, this method will be used.
Retain pre-developed runoff characteristics. Do not increase the rate of runoff from the development.
As documented in the subsections above, there is a decrease in the rate of runoff from the development to all points of analysis.
Analyze the waterway or channel for stability under the planned rate of discharge using the Standard for Grassed Waterways or Standard for Channel Stabilization, as appropriate. Peak flows from the 2-and 10-year storms shall be analyzed.
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As noted above, the proposed peak flows meet the above reductions, thereby achieving off-site stability, therefore; this section is not applicable.
C. Modify the waterway or channel to a stable design condition.
As noted above, the proposed peak flows meet the above reductions, thereby achieving off-site stability, therefore; this section is not applicable.
Downstream of the Point of Discharge (Off-Site Stability Analysis)
In addition to ensuring erosion does not occur at the point of discharge, areas downstream and beyond the immediate area of site development may be damaged due to erosive forces resulting from extended duration of hydrograph peak flows. An unintended consequence of the practice of detaining and slowly releasing stormwater is the ability for peak flows to be sustained for longer periods of time, offering an opportunity for upstream discharges to coincide with project site discharges. The resulting combined discharge may be equal to or even exceed that of the pre-development condition.
To limit the potential for such an occurrence the designer may choose either of two approaches for downstream stability protection:
Examine hydraulic characteristics of the receiving stream channel considering upstream discharge in combination with site discharge to assess channel stability. The scope and scale of the analysis shall be appropriate to the scale of the project and the post development peak discharge rate and volume. Of particular concern are hydraulic control points, (culverts, bridges, etc.), bends in streams and sudden changes in channel cross sections downstream of the discharge point. The following may be utilized to assess stability:
The proposed design utilizes approach 2 as described below.
In lieu of performing a comprehensive watershed analysis, design a detention facility that reduces peak flows to the following levels. Infiltration may be used to meet these criteria:
2-year storm – 50% of the predevelopment peak
10-year storm – 75% of the predevelopment peak
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The post-construction runoff hydrographs for the current and projected two-, 10-, and 100-year storm events do not exceed, at any point in time, the pre-construction runoff hydrographs for the same storm events.
Reductions in peak flows are to be compared to pre-developed drainage area points of discharge in the event that drainage is re-directed in the post developed condition. Reductions are only required of the developed or modified portions of the project site.
As documented in the subsections above, the proposed peak flows meet the above reductions, thereby achieving off-site stability.
14. CONCLUSION
The proposed development has been designed to control stormwater runoff in a manner consistent with the existing drainage patterns. In addition, the proposed development satisfies the runoff quantity, quality and groundwater recharge requirements set forth by the Township of Jackson Land Use Ordinance, Pinelands CMP and NJAC 7:8 through the use of the proposed small-scale underground infiltration basins. With this stated, it is evident that the proposed development will not have a negative impact on the existing drainage conditions, water quality or groundwater recharge on-site or within the vicinity of the subject site.
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APPENDIX
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NRCS WEB SOIL SURVEY
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MAP LEGEND
The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.
Date(s) aerial images were photographed: Jun 4, 2022—Jul 22, 2022
Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.
Soil Survey Area: Ocean County, New Jersey
Survey Area Data: Version 20, Aug 30, 2022
This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.
Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.
| B | |
|---|---|
| B/D | |
| C | C/D |
| D | Not rated or not available |
| Soil Rating Points | |
| A | |
| A/D | |
Please rely on the bar scale on each map sheet for map measurements.
Soil Rating Points
The soil surveys that comprise your AOI were mapped at 1:24,000.
MAP INFORMATION
Hydrologic Soil Group—Ocean County, New Jersey
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Hydrologic Soil Group—Ocean County, New Jersey
Hydrologic Soil Group
| Map unit symbol | Map unit name | Rating | Acres in AOI | Percent of AOI |
|---|---|---|---|---|
| DofgB | Downer gravelly sandy loam, gravelly substratum, 2 to 5 percent slopes | A | 1.2 | 100.0% |
| Totals for Area of Interest | 1.2 | 100.0% | ||
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
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Hydrologic Soil Group—Ocean County, New Jersey
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
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HYDROGRAPH SUMMARY REPORTS – EXISTING & PROPOSED CONDITIONS 2, 10, & 100-YEAR
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Project Notes
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NRCS-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Defined 1 rainfall events from NJ-DEP IDF
Defined 1 rainfall events from NJ-DEP IDF
Printed 2/10/2026
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| 2026-02 Existing and Proposed | |
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
|---|---|
| HydroCAD\textregistered 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC | Page 3 |
2026-02 Existing and Proposed Prepared by Dynamic Engineering HydroCAD\textregistered 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Printed 2/10/2026 Page 4
Rainfall Events Listing (selected events)
Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC
1 2-Year-Current NOAA 24-hr D Default 24.00 1 3.42 2
2 2-Year-Projected NOAA 24-hr D Default 24.00 1 4.04 2
3 10-Year-Current NOAA 24-hr D Default 24.00 1 5.38 2
4 10-Year-Projected NOAA 24-hr D Default 24.00 1 6.34 2
5 100-Year-Current NOAA 24-hr D Default 24.00 1 9.48 2
6 100-Year-Projected NOAA 24-hr D Default 24.00 1 11.41 2
| Area Listing (selected nodes) | ||
| Area (acres) | CN | Description (subcatchment-numbers) |
|---|---|---|
| 1.470 | 39 | >75% Grass cover, Good, HSG A (3S, 7S, 11S, 14S, 19S) |
| 0.710 | 98 | Paved parking, HSG A (4S, 6S, 10S, 12S) |
| 0.160 | 98 | Roofs, HSG A (4S, 15S) |
| 2.340 | 61 | TOTAL AREA |
Page 24
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2026-02 Existing and Proposed Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 5 2026-02 Existing and Proposed Prepared by Dynamic Engineering
HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Soil Listing (selected nodes) Ground Covers (selected nodes)
Area (acres) Soil Group Subcatchment Numbers HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers
2.340 HSG A 3S, 4S, 6S, 7S, 10S, 11S, 12S, 14S, 15S, 19S 1.470 0.000 0.000 0.000 0.000 1.470 >75% Grass cover, Good
0.000 HSG B 3S, 7S, 11S,
0.000 HSG C 14S,
0.000 HSG D 19S
0.000 Other 0.710 0.000 0.000 0.000 0.000 0.710 Paved parking 4S, 6S,
2.340 TOTAL AREA 10S, 12S
0.160 0.000 0.000 0.000 0.000 0.160 Roofs 4S, 15S
2.340 0.000 0.000 0.000 0.000 2.340 TOTAL AREA
Page 25
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Printed 2/10/2026
Page 7
Pipe Listing (selected nodes)
| Line# | Node Number | In-Invert (feet) | Out-Invert (feet) | Length (feet) | Slope (ft/ft) | n | Width (inches) | Diam/Height (inches) | Inside-Fill (inches) | Node Name |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 10S | 0.00 | 0.00 | 297.0 | 0.0035 | 0.011 | 0.0 | 15.0 | 0.0 | |
| 2 | 11S | 0.00 | 0.00 | 297.0 | 0.0035 | 0.011 | 0.0 | 15.0 | 0.0 | |
| 3 | 15S | 0.00 | 0.00 | 207.0 | 0.0100 | 0.010 | 0.0 | 8.0 | 0.0 | |
| 4 | 21P | 117.50 | 117.40 | 22.0 | 0.0045 | 0.013 | 0.0 | 15.0 | 0.0 |
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 8
| Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points | ||
| Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN | ||
| Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method | ||
| Subcatchment3S: Ex. Study Area West | Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=0.01" Flow Length=98' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
|---|---|---|
| Subcatchment4S: Ex. Study Area West | Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=3.19" Flow Length=248' Tc=10.0 min CN=98 Runoff=0.19 cfs 0.024 af | |
| Subcatchment6S: Ex. Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=3.19" Flow Length=82' Slope=0.0150 ' /" Tc=10.0 min CN=98 Runoff=0.06 cfs 0.008 af | |
| Subcatchment7S: Ex. Study Area Road | Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=0.01" Flow Length=61' Slope=0.0100 ' /" Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment10S: Study Area WQ MTD | Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=3.19" Flow Length=352' Tc=10.0 min CN=98 Runoff=1.30 cfs 0.162 af | |
| Subcatchment11S: Study Area WQ MTD | Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=0.01" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment12S: Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=3.19" Flow Length=35' Slope=0.0322 ' /" Tc=10.0 min CN=98 Runoff=0.06 cfs 0.008 af | |
| Subcatchment14S: Study Area West | Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=0.01" Flow Length=48' Slope=0.0850 ' /" Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment15S: Study Area Roof (Imp) | Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=3.19" Flow Length=207' Slope=0.0100 ' /" Tc=10.0 min CN=98 Runoff=0.23 cfs 0.029 af | |
| Subcatchment19S: Study Area Road | Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=0.01" Flow Length=58' Slope=0.0300 ' /" Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Pond 21P: Basin A Routing (StormBrixx) Discarded=0.70 cfs | Peak Elev=117.82' Storage=937 cf Inflow=1.53 cfs 0.191 af 0.191 af Primary=0.00 cfs 0.000 af Outflow=0.70 cfs 0.191 af | |
| Link 5L: Ex Study Area West (Total) | Inflow=0.19 cfs 0.024 af Primary=0.19 cfs 0.024 af | |
| Link 8L: Existing Study Area Road (Total) | Inflow=0.06 cfs 0.008 af Primary=0.06 cfs 0.008 af | |
| Link 10L: Study Area Study Area WQ MTD A-110 (Total) | Inflow=1.30 cfs 0.162 af Primary=1.30 cfs 0.162 af | |
| Link 14L: Study Area West (Total) | Inflow=0.00 cfs 0.000 af Primary=0.00 cfs 0.000 af | |
| Link 16L: Study Area Basin A (Total) | Inflow=1.53 cfs 0.191 af Primary=1.53 cfs 0.191 af | |
Page 26
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2026-02 Existing and Proposed Prepared by Dynamic Engineering HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC NOAA 24-hr D 2-Year-Current Rainfall=3.42" Printed 2/10/2026 Page 9
Link 18L: Study Area Road Undetained (Total) Inflow=0.06 cfs 0.008 af Primary=0.06 cfs 0.008 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.232 af Average Runoff Depth = 1.19' 62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
2026-02 Existing and Proposed Prepared by Dynamic Engineering HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC NOAA 24-hr D 2-Year-Current Rainfall=3.42" Printed 2/10/2026 Page 10
| Summary for Subcatchment 3S: Ex. Study Area West (Perv) | ||
| Runoff = | 0.00 cfs @ | 24.00 hrs, Volume= |
|---|---|---|
| Routed to Link 5L : | Ex Study Area West (Total) | |
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total, Increased to minimum Tc = 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
Page 27
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.19 cfs @ 12.19 hrs, Volume= 0.024 af, Depth= 3.19" Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.1 148 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
2.0 248 Total Increased to minimum T= 10.0 min
2.0 248 Total, Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Current Rainfall=3.42" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 12 |
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.06 cfs @ 12.19 hrs, Volume= 0.008 af, Depth= 3.19"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
1.0 82 0.0150 1.32
Sheet Flow, A-B
Smooth surfaces n= 0.011 P2= 4.04"
1.0 82 Total Increased to minimum Tc = 10.0 min
1.0 82 Total, Increased to minimum Tc = 10.0 min
Subcatchment 6S: Ex. Study Area Road (Imp)
Page 28
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
Runoff = 0.00 cfs @ 24.00 hrs, Volume= 0.000 af, Depth= 0.01"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
| Area (ac) | CN | Description |
|---|---|---|
| 0.120 | 39 | >75% Grass cover, Good, HSG A |
| 0.120 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 1.0 | 61 | 0.0100 1.06 |
| Sheet Flow, A-B | ||
| Smooth surfaces | ||
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Current Rainfall=3.42" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 14 |
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 1.30 cfs @ 12.19 hrs, Volume= 0.162 af, Depth= 3.19"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Page 29
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 15
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.00 cfs @ 24.00 hrs, Volume= 0.000 af, Depth= 0.01"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perm= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total, Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Current Rainfall=3.42" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 16 |
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.06 cfs @ 12.19 hrs, Volume= 0.008 af, Depth= 3.19" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff = 0.06 cfs @ 12.19 hrs, Volume= 0.008 af, Depth= 3.19" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
0.4 35 0.0322 1.52
Sheet Flow, A-B
Smooth surfaces n= 0.011
P2= 4.04"
0.4 35 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Study Area Road Undetained (Imp)
Page 30
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 17
Summary for Subcatchment 14S: Study Area West Undetained
Runoff = 0.00 cfs @ 24.00 hrs, Volume= 0.000 af, Depth= 0.01"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.310 39 >75% Grass cover, Good, HSG A
0.310 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
2.7 48 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Current Rainfall=3.42" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 18 |
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.23 cfs @ 12.19 hrs, Volume= 0.029 af, Depth= 3.19"
Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perm= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
Page 31
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 19
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff = 0.00 cfs @ 24.00 hrs, Volume= 0.000 af, Depth= 0.01"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Current Rainfall=3.42"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
| 4.8 | 58 | Total. Increased to minimum Tc = 10.0 min |
Subcatchment 19S: Study Area Road Undetained (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Current Rainfall=3.42" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 20 |
Summary for Pond 21P: Basin A Routing (StormBrixx)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 3.10" for 2-Year-Current event |
|---|---|
| Inflow = | 1.53 cfs @ 12.19 hrs, Volume= 0.191 af |
| Outflow = | 0.70 cfs @ 12.56 hrs, Volume= 0.191 af, Atten= 54%, Lag= 22.1 min |
| Discarded = | 0.70 cfs @ 12.56 hrs, Volume= 0.191 af |
| Primary = | 0.00 cfs @ 0.00 hrs, Volume= 0.000 af |
| Routed to Link 14L : Study Area West (Total) | |
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 117.82' @ 12.56 hrs Surf.Area= 3,001 sf Storage= 937 cf
Plug-Flow detention time=6.8 min calculated for 0.191 af (100% of inflow) Center-of-Mass det. time=6.8 min (773.5 - 766.7)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W x 94.88'L x 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50' / 117.40' S= 0.0045 '/ Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.70 cfs @ 12.56 hrs HW=117.82' (Free Discharge) —3=Exfiltration ( Controls 0.70 cfs) | |||
| Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge) —1=Culvert ( Controls 0.00 cfs) —2=Orifice ( Controls 0.00 cfs) | |||
Page 32
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 21
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx® SD)
Inside = 23.7" W × 36.0" H => 5.75 sf × 3.95' L = 22.7 cf
Outside = 23.7" W × 36.0" H => 5.93 sf × 3.95' L = 23.4 cf
24 Chambers/Row x 3.95' Long = 94.88' Row Length
16 Rows x 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers x 22.7 cf = 8.728.7 cf Chamber Storage
384 Chambers x 23.4 cf = 8.998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' x 31.63' x 3.00'
384 Chambers
333.3 cy Field
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 22
Pond 21P: Basin A Routing (StormBrixx)
Page 33
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 23
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, | Inflow Depth = 0.29" for 2-Year-Current event | |
|---|---|---|---|---|
| Inflow = | 0.19 cfs @ | 12.19 hrs, | Volume= 0.024 af | |
| Primary = | 0.19 cfs @ | 12.19 hrs, | Volume= 0.024 af, | Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 24
Summary for Link 8L: Existing Study Area Road (Total)
| Inflow Area = | 0.150 ac, 20.00% Impervious, Inflow Depth = 0.64" for 2-Year-Current event |
|---|---|
| Inflow = | 0.06 cfs @ 12.19 hrs, Volume= 0.008 af |
| Primary = | 0.06 cfs @ 12.19 hrs, Volume= 0.008 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
Page 34
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 25
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Inflow Area = 0.630 ac, 96.83% Impervious, Inflow Depth = 3.09" for 2-Year-Current event
Inflow = 1.30 cfs @ 12.19 hrs, Volume = 0.162 af
Primary = 1.30 cfs @ 12.19 hrs, Volume = 0.162 af, Atten = 0%, Lag = 0.0 min
Routed to Link 16L : Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 26
Summary for Link 14L: Study Area West (Total)
| Inflow Area = | 1.050 ac, 68.57% Impervious, Inflow Depth = 0.00" for 2-Year-Current event |
|---|---|
| Inflow = | 0.00 cfs @ 24.00 hrs, Volume= 0.000 af |
| Primary = | 0.00 cfs @ 24.00 hrs, Volume= 0.000 af, Atten= 0%. Laq= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
Page 35
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 27
Summary for Link 16L: Study Area Basin A (Total)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 3.10" for 2-Year-Current event |
|---|---|
| Inflow = | 1.53 cfs @ 12.19 hrs, Volume= 0.191 af |
| Primary = | 1.53 cfs @ 12.19 hrs, Volume= 0.191 af, Atten= 0%, Lag= 0.0 min |
| Routed to Pond 21P : Basin A Routing (StormBrixx) | |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 28
Summary for Link 18L: Study Area Road Undetained (Total)
| Inflow Area = | 0.120 ac, 25.00% Impervious, Inflow Depth = 0.80" for 2-Year-Current event |
|---|---|
| Inflow = | 0.06 cfs @ 12.19 hrs, Volume= 0.008 af |
| Primary = | 0.06 cfs @ 12.19 hrs, Volume= 0.008 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
Page 36
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 29
| Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points | |||
| Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN | |||
| Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method | |||
| Subcatchment3S: Ex. Study Area West | Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=0.05" Flow Length=98' Tc=10.0 min CN=39 Runoff=0.01 cfs 0.004 af | ||
|---|---|---|---|
| Subcatchment4S: Ex. Study Area West | Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=3.81" Flow Length=248' Tc=10.0 min CN=98 Runoff=0.23 cfs 0.029 af | ||
| Subcatchment6S: Ex. Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=3.81" Flow Length=82' Slope=0.0150 /" Tc=10.0 min CN=98 Runoff=0.08 cfs 0.010 af | ||
| Subcatchment7S: Ex. Study Area Road | Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=0.05" Flow Length=61' Slope=0.0100 /" Tc=10.0 min CN=39 Runoff=0.00 cfs 0.001 af | ||
| Subcatchment10S: Study Area WQ MTD | Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=3.81" Flow Length=352' Tc=10.0 min CN=98 Runoff=1.54 cfs 0.193 af | ||
| Subcatchment11S: Study Area WQ MTD | Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=0.05" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | ||
| Subcatchment12S: Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=3.81" Flow Length=35' Slope=0.0322 /" Tc=10.0 min CN=98 Runoff=0.08 cfs 0.010 af | ||
| Subcatchment14S: Study Area West | Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=0.05" Flow Length=48' Slope=0.0850 /" Tc=10.0 min CN=39 Runoff=0.00 cfs 0.001 af | ||
| Subcatchment15S: Study Area Roof (Imp) | Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=3.81" Flow Length=207' Slope=0.0100 /" Tc=10.0 min CN=98 Runoff=0.28 cfs 0.035 af | ||
| Subcatchment19S: Study Area Road | Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=0.05" Flow Length=58' Slope=0.0300 /" Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | ||
| Pond 21P: Basin A Routing (StormBrixx) Discarded=0.70 cfs | Peak Elev=117.98' Storage=1,394 cf Inflow=1.81 cfs 0.228 af 0.228 af Primary=0.00 cfs 0.000 af Outflow=0.70 cfs 0.228 af | ||
| Link 5L: Ex Study Area West (Total) | Inflow=0.23 cfs 0.032 af Primary=0.23 cfs 0.032 af | ||
| Link 8L: Existing Study Area Road (Total) | Inflow=0.08 cfs 0.010 af Primary=0.08 cfs 0.010 af | ||
| Link 10L: Study Area Study Area WQ MTD A-110 (Total) | Inflow=1.54 cfs 0.194 af Primary=1.54 cfs 0.194 af | ||
| Link 14L: Study Area West (Total) | Inflow=0.00 cfs 0.001 af Primary=0.00 cfs 0.001 af | ||
| Link 16L: Study Area Basin A (Total) | Inflow=1.81 cfs 0.228 af Primary=1.81 cfs 0.228 af | ||
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 30
Link 18L: Study Area Road Undetained (Total) Inflow=0.08 cfs 0.010 af
Primary=0.08 cfs 0.010 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.282 af Average Runoff Depth = 1.45"
62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
Page 37
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 31
Summary for Subcatchment 3S: Ex. Study Area West (Perv)
Runoff = 0.01 cfs @ 17.02 hrs, Volume= 0.004 af, Depth= 0.05"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total, Increased to minimum Tc = 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Projected Rainfall=4.04" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 32 |
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.23 cfs @ 12.19 hrs, Volume= 0.029 af, Depth= 3.81"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B
1.1 148 0.0200 2.28 Smooth surfaces n= 0.011 P2= 4.04"
Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
2.0 248 Total, Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
Page 38
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 33
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.08 cfs @ 12.19 hrs, Volume= 0.010 af, Depth= 3.81"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
1.0 82 0.0150 1.32 Sheet Flow, A-B Smooth surfaces n = 0.011 P2= 4.04"
1.0 82 Total, Increased to minimum Tc = 10.0 min
Subcatchment 6S: Ex. Study Area Road (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 34
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
Runoff = 0.00 cfs @ 17.02 hrs, Volume= 0.001 af, Depth= 0.05" Routed to Link 8L : Existing Study Area Road (Total)
Runoff = 0.00 cfs @ 17.02 hrs, Volume= 0.001 af, Depth= 0.05"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
| Area (ac) | CN | Description |
|---|---|---|
| 0.120 | 39 | >75% Grass cover, Good, HSG A |
| 0.120 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 1.0 | 61 | 0.0100 1.06 |
| Sheet Flow, A-B | ||
| Smooth surfaces | n= 0.011 P2= 4.04" | |
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
Page 39
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 35
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 1.54 cfs @ 12.19 hrs, Volume= 0.193 af, Depth= 3.81"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B
1.3 297 0.0035 3.68 4.52 Smooth surfaces n= 0.011 P2= 4.04"
Pipe Channel, B-C
15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31'
n= 0.011 Concrete pipe, straight & clean
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 36
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.00 cfs @ 17.02 hrs, Volume= 0.000 af, Depth= 0.05"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B
0.2 46 0.0380 3.96 Grass: Short n= 0.150 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Shallow Concentrated Flow, B-C
Paved Kv= 20.3 fps
Pipe Channel, C-D
15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31'
n= 0.011 Concrete pipe, straight & clean
2.9 351 Total. Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Hydrograph
Page 40
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 37
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.08 cfs @ 12.19 hrs, Volume= 0.010 af, Depth= 3.81"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.4 35 0.0322 1.52 Sheet Flow, A-B Smooth surfaces n = 0.011 P2= 4.04"
0.4 35 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Study Area Road Undetained (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D 2-Year-Projected Rainfall=4.04" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC | Page 38 |
Summary for Subcatchment 14S: Study Area West Undetained
Runoff = 0.00 cfs @ 17.02 hrs, Volume= 0.001 af, Depth= 0.05"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
| Area (ac) | CN | Description |
|---|---|---|
| 0.310 | 39 | >75% Grass cover, Good, HSG A |
| 0.310 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 2.7 | 48 | 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04" |
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
Page 41
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 39
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.28 cfs @ 12.19 hrs, Volume= 0.035 af, Depth= 3.81"
Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perim= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 40
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff = 0.00 cfs @ 17.02 hrs, Volume= 0.000 af, Depth= 0.05"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
Page 42
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 41
Summary for Pond 21P: Basin A Routing (StormBrixx)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 3.70" for 2-Year-Projected event
Inflow = 1.81 cfs @ 12.19 hrs, Volume= 0.228 af
Outflow = 0.70 cfs @ 12.63 hrs, Volume= 0.228 af, Atten= 62%, Lag= 26.5 min
Discarded = 0.70 cfs @ 12.63 hrs, Volume= 0.228 af
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routed to Link 14L : Study Area West (Total)
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 117.98' @ 12.63 hrs Surf.Area= 3,001 sf Storage= 1,394 cf
Plug-Flow detention time= 10.0 min calculated for 0.228 af (100% of inflow) Center-of-Mass det. time= 10.0 min (773.3 - 763.3)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W x 94.88'L x 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50'/ 117.40' S= 0.0045'/' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.70 cfs @ 12.63 hrs HW=117.98' (Free Discharge) —3=Exfiltration ( Controls 0.70 cfs) | |||
| Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge) —1=Culvert ( Controls 0.00 cfs) —2=Orifice ( Controls 0.00 cfs) | |||
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 42
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx SD)
Inside = 23.7" W × 36.0" H => 5.75 sf × 3.95' L = 22.7 cf
Outside = 23.7" W × 36.0" H => 5.93 sf × 3.95' L = 23.4 cf
24 Chambers/Row × 3.95' Long = 94.88' Row Length
16 Rows × 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers × 22.7 cf = 8,728.7 cf Chamber Storage
384 Chambers × 23.4 cf = 8,998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' × 31.63' × 3.00'
384 Chambers
333.3 cy Field
Page 43
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 43
Pond 21P: Basin A Routing (StormBrixx)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 44
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, | Inflow Depth = 0.38" for 2-Year-Projected event | ||
|---|---|---|---|---|---|
| Inflow = | 0.23 cfs @ | 12.19 hrs, | Volume= 0.032 af | ||
| Primary = | 0.23 cfs @ | 12.19 hrs, | Volume= 0.032 af, | Atten= 0%, | Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
Page 44
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 45
Summary for Link 8L: Existing Study Area Road (Total)
| Inflow Area = | 0.150 ac, 20.00% Impervious, Inflow Depth = 0.80" for 2-Year-Projected event |
|---|---|
| Inflow = | 0.08 cfs @ 12.19 hrs, Volume= 0.010 af |
| Primary = | 0.08 cfs @ 12.19 hrs, Volume= 0.010 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 46
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
| Inflow Area = | 0.630 ac, 96.83% Impervious, Inflow Depth = 3.69" for 2-Year-Projected event |
|---|---|
| Inflow = | 1.54 cfs @ 12.19 hrs, Volume= 0.194 af |
| Primary = | 1.54 cfs @ 12.19 hrs, Volume= 0.194 af, Atten= 0%, Lag= 0.0 min |
| Routed to Link 161 : Study Area Basin A (Total) | |
Routed to Link 16L : Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Page 45
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 47
Summary for Link 14L: Study Area West (Total)
| Inflow Area = | 1.050 ac, 68.57% Impervious, Inflow Depth = 0.01" for 2-Year-Projected event |
|---|---|
| Inflow = | 0.00 cfs @ 17.02 hrs, Volume= 0.001 af |
| Primary = | 0.00 cfs @ 17.02 hrs, Volume= 0.001 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 48
Summary for Link 16L: Study Area Basin A (Total)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 3.70" for 2-Year-Projected event |
|---|---|
| Inflow = | 1.81 cfs @ 12.19 hrs, Volume= 0.228 af |
| Primary = | 1.81 cfs @ 12.19 hrs, Volume= 0.228 af, Atten= 0%, Lag= 0.0 min |
| Routed to Pond 21P : Basin A Routing (StormBrixx) | |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
Hydrograph
Page 46
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2026-02 Existing and Proposed NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 49
Summary for Link 18L: Study Area Road Undetained (Total)
| Inflow Area = | 0.120 ac, 25.00% Impervious, Inflow Depth = 0.99" for 2-Year-Projected event |
|---|---|
| Inflow = | 0.08 cfs @ 12.19 hrs, Volume= 0.010 af |
| Primary = | 0.08 cfs @ 12.19 hrs, Volume= 0.010 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 50
| Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points | ||
| Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN | ||
| Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method | ||
| Subcatchment3S: Ex. Study Area West | Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=0.28" Flow Length=98' Tc=10.0 min CN=39 Runoff=0.05 cfs 0.022 af | |
|---|---|---|
| Subcatchment4S: Ex. Study Area West | Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=5.14" Flow Length=248' Tc=10.0 min CN=98 Runoff=0.30 cfs 0.039 af | |
| Subcatchment6S: Ex. Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=5.14" Flow Length=82' Slope=0.0150 /' Tc=10.0 min CN=98 Runoff=0.10 cfs 0.013 af | |
| Subcatchment7S: Ex. Study Area Road | Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=0.28" Flow Length=61' Slope=0.0100 /' Tc=10.0 min CN=39 Runoff=0.01 cfs 0.003 af | |
| Subcatchment10S: Study Area WQ MTD | Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=5.14" Flow Length=352' Tc=10.0 min CN=98 Runoff=2.05 cfs 0.261 af | |
| Subcatchment11S: Study Area WQ MTD | Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=0.28" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment12S: Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=5.14" Flow Length=35' Slope=0.0322 /' Tc=10.0 min CN=98 Runoff=0.10 cfs 0.013 af | |
| Subcatchment14S: Study Area West | Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=0.28" Flow Length=48' Slope=0.0850 /' Tc=10.0 min CN=39 Runoff=0.02 cfs 0.007 af | |
| Subcatchment15S: Study Area Roof (Imp) | Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=5.14" Flow Length=207' Slope=0.0100 /' Tc=10.0 min CN=98 Runoff=0.37 cfs 0.047 af | |
| Subcatchment19S: Study Area Road | Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=0.28" Flow Length=58' Slope=0.0300 /' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.002 af | |
| Pond 21P: Basin A Routing (StormBrixx) Discarded=0.70 cfs | Peak Elev=118.37' Storage=2,530 cf Inflow=2.42 cfs 0.309 af 0.309 af Primary=0.00 cfs 0.000 af Outflow=0.70 cfs 0.309 af | |
| Link 5L: Ex Study Area West (Total) | Inflow=0.30 cfs 0.061 af Primary=0.30 cfs 0.061 af | |
| Link 8L: Existing Study Area Road (Total) | Inflow=0.10 cfs 0.016 af Primary=0.10 cfs 0.016 af | |
| Link 10L: Study Area Study Area WQ MTD A-110 (Total) | Inflow=2.05 cfs 0.262 af Primary=2.05 cfs 0.262 af | |
| Link 14L: Study Area West (Total) | Inflow=0.02 cfs 0.007 af Primary=0.02 cfs 0.007 af | |
| Link 16L: Study Area Basin A (Total) | Inflow=2.42 cfs 0.309 af | |
Link 16L: Study Area Basin A (Total) Inflow=2.42 cfs 0.309 af Primary=2.42 cfs 0.309 af
Page 47
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2026-02 Existing and Proposed Prepared by Dynamic Engineering HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC NOAA 24-hr D 10-Year-Current Rainfall=5.38" Printed 2/10/2026 Page 51
Link 18L: Study Area Road Undetained (Total) Inflow=0.10 cfs 0.015 af Primary=0.10 cfs 0.015 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.408 af Average Runoff Depth = 2.09" 62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
| 2026-02 Existing and Proposed | NOAA 24-hr D 10-Year-Current Rainfall=5.38" | |
|---|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 | |
| HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC | Page 52 |
Summary for Subcatchment 3S: Ex. Study Area West (Perv)
Runoff = 0.05 cfs @ 12.93 hrs, Volume= 0.022 af, Depth= 0.28"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total, Increased to minimum Tc= 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
Page 48
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 53
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.30 cfs @ 12.19 hrs, Volume= 0.039 af, Depth= 5.14" Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.1 148 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
2.0 248 Total Increased to minimum Tc = 10.0 min
2.0 248 Total, Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 10-Year-Current | Rainfall=5.38" |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 54 |
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.10 cfs @ 12.19 hrs, Volume= 0.013 af, Depth= 5.14" Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
1.0 82 0.0150 1.32
Sheet Flow, A-B
Smooth surfaces n= 0.011 P2= 4.04"
1.0 82 Total Increased to minimum Tc = 10.0 min
1.0 82 Total, Increased to minimum Tc = 10.0 min
Subcatchment 6S: Ex. Study Area Road (Imp)
Page 49
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 55
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
Runoff = 0.01 cfs @ 12.93 hrs, Volume= 0.003 af, Depth= 0.28"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
| Area (ac) | CN | Description |
|---|---|---|
| 0.120 | 39 | >75% Grass cover, Good, HSG A |
| 0.120 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 1.0 | 61 | 0.0100 1.06 |
| Sheet Flow, A-B | ||
| Smooth surfaces | n= 0.011 P2= 4.04" | |
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 10-Year-Current | Rainfall=5.38'' |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 56 |
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 2.05 cfs @ 12.19 hrs, Volume= 0.261 af, Depth= 5.14" Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total Increased to minimum Tc = 10.0 min
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Page 50
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 57
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.00 cfs @ 12.93 hrs, Volume= 0.000 af, Depth= 0.28"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perm= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total, Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 10-Year-Current | Rainfall=5.38'' |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 58 |
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.10 cfs @ 12.19 hrs, Volume= 0.013 af, Depth= 5.14" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff = 0.10 cfs @ 12.19 hrs, Volume= 0.013 af, Depth= 5.14" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Page 51
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 59
Summary for Subcatchment 14S: Study Area West Undetained
Runoff = 0.02 cfs @ 12.93 hrs, Volume= 0.007 af, Depth= 0.28"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.310 39 >75% Grass cover, Good, HSG A
0.310 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.7 48 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
| 2026-02 Existing and Proposed | NOAA 24-hr D | 10-Year-Current | Rainfall=5.38" |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 60 |
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.37 cfs @ 12.19 hrs, Volume= 0.047 af, Depth= 5.14"
Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perm= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
Page 52
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 61
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff = 0.00 cfs @ 12.93 hrs, Volume= 0.002 af, Depth= 0.28"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 10-Year-Current Rainfall=5.38"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
| 4.8 | 58 | Total Increased to minimum Tc = 10.0 min |
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 10-Year-Current | Rainfall=5.38" |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 62 |
Summary for Pond 21P: Basin A Routing (StormBrixx)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 5.01" for 10-Year-Current event |
|---|---|
| Inflow = | 2.42 cfs @ 12.19 hrs, Volume= 0.309 af |
| Outflow = | 0.70 cfs @ 12.76 hrs, Volume= 0.309 af, Atten= 71%, Lag= 34.5 min |
| Discarded = | 0.70 cfs @ 12.76 hrs, Volume= 0.309 af |
| Primary = | 0.00 cfs @ 0.00 hrs, Volume= 0.000 af |
| Routed to Link 14L: Study Area West (Total) | |
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 118.37' @ 12.76 hrs Surf.Area= 3,001 sf Storage= 2,530 cf
Plug-Flow detention time= 18.8 min calculated for 0.309 af (100% of inflow) Center-of-Mass det. time= 18.8 min (777.0 - 758.2)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W x 94.88'L x 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50' / 117.40' S= 0.0045'' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0'' Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.70 cfs @ 12.76 hrs HW=118.37' (Free Discharge) —3=Exfiltration ( Controls 0.70 cfs) | |||
| Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge) —1=Culvert ( Controls 0.00 cfs) —2=Orifice ( Controls 0.00 cfs) | |||
Page 53
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 63
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx® SD)
Inside = 23.7" W x 36.0" H => 5.75 sf x 3.95" L = 22.7 cf
Outside = 23.7" W x 36.0" H => 5.93 sf x 3.95" L = 23.4 cf
24 Chambers/Row x 3.95' Long = 94.88' Row Length
16 Rows x 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers x 22.7 cf = 8.728.7 cf Chamber Storage
384 Chambers x 23.4 cf = 8.998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' x 31.63' x 3.00'
384 Chambers
333.3 cy Field
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 64
Pond 21P: Basin A Routing (StormBrixx)
Page 54
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 65
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, | Inflow Depth = 0.71" for 10-Year-Current event | |
|---|---|---|---|---|
| Inflow = | 0.30 cfs @ | 12.19 hrs, | Volume= 0.061 af | |
| Primary = | 0.30 cfs @ | 12.19 hrs, | Volume= 0.061 af, | Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 66
Summary for Link 8L: Existing Study Area Road (Total)
| Inflow Area = | 0.150 ac, 20.00% Impervious, Inflow Depth = 1.26" for 10-Year-Current event |
|---|---|
| Inflow = | 0.10 cfs @ 12.19 hrs, Volume= 0.016 af |
| Primary = | 0.10 cfs @ 12.19 hrs, Volume= 0.016 af, Atten= 0%, Laq= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
Page 55
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 67
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Inflow Area = 0.630 ac, 96.83% Impervious, Inflow Depth = 4.99" for 10-Year-Current event
Inflow = 2.05 cfs @ 12.19 hrs, Volume = 0.262 af
Primary = 2.05 cfs @ 12.19 hrs, Volume = 0.262 af, Atten = 0%, Lag = 0.0 min
Routed to Link 16L : Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 68
Summary for Link 14L: Study Area West (Total)
| Inflow Area = | 1.050 ac, 68.57% Impervious, Inflow Depth = 0.08" for 10-Year-Current event |
|---|---|
| Inflow = | 0.02 cfs @ 12.93 hrs, Volume= 0.007 af |
| Primary = | 0.02 cfs @ 12.93 hrs, Volume= 0.007 af, Atten= 0%. Laq= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
Page 56
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 69
Summary for Link 16L: Study Area Basin A (Total)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 5.01" for 10-Year-Current event |
|---|---|
| Inflow = | 2.42 cfs @ 12.19 hrs, Volume= 0.309 af |
| Primary = | 2.42 cfs @ 12.19 hrs, Volume= 0.309 af, Atten= 0%, Lag= 0.0 min |
| Routed to Pond 21P : Basin A Routing (StormBrixx) | |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 70
Summary for Link 18L: Study Area Road Undetained (Total)
| Inflow Area = | 0.120 ac, 25.00% Impervious, Inflow Depth = 1.50" for 10-Year-Current event |
|---|---|
| Inflow = | 0.10 cfs @ 12.19 hrs, Volume= 0.015 af |
| Primary = | 0.10 cfs @ 12.19 hrs, Volume= 0.015 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
Page 57
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 71
| Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method | ||
| Subcatchment3S: Ex. Study Area West | Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=0.55" Flow Length=98' Tc=10.0 min CN=39 Runoff=0.14 cfs 0.042 af | |
|---|---|---|
| Subcatchment4S: Ex. Study Area West | Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=6.10" Flow Length=248' Tc=10.0 min CN=98 Runoff=0.36 cfs 0.046 af | |
| Subcatchment6S: Ex. Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=6.10" Flow Length=82' Slope=0.0150 /" Tc=10.0 min CN=98 Runoff=0.12 cfs 0.015 af | |
| Subcatchment7S: Ex. Study Area Road | Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=0.55" Flow Length=61' Slope=0.0100 /" Tc=10.0 min CN=39 Runoff=0.02 cfs 0.005 af | |
| Subcatchment10S: Study Area WQ MTD | Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=6.10" Flow Length=352' Tc=10.0 min CN=98 Runoff=2.42 cfs 0.310 af | |
| Subcatchment11S: Study Area WQ MTD | Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=0.55" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.001 af | |
| Subcatchment12S: Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=6.10" Flow Length=35' Slope=0.0322 /" Tc=10.0 min CN=98 Runoff=0.12 cfs 0.015 af | |
| Subcatchment14S: Study Area West | Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=0.55" Flow Length=48' Slope=0.0850 /" Tc=10.0 min CN=39 Runoff=0.05 cfs 0.014 af | |
| Subcatchment15S: Study Area Roof (Imp) Flow Length=207' Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=6.10" Flow Length=207' Slope=0.0100 /" Tc=10.0 min CN=98 Runoff=0.44 cfs 0.056 af | ||
| Subcatchment19S: Study Area Road | Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=0.55" Flow Length=58' Slope=0.0300 /" Tc=10.0 min CN=39 Runoff=0.01 cfs 0.004 af | |
| Pond 21P: Basin A Routing (StormBrixx) Discarded=0.70 cfs Peak Elev=118.68' Storage=3,445 cf Inflow=2.86 cfs 0.367 af | ||
| Link 5L: Ex Study Area West (Total) | Primary=0.00 cfs 0.000 af Outflow=0.70 cfs 0.367 af | |
| Link 8L: Existing Study Area Road (Total) | Primary=0.45 cfs Inflow=0.45 cfs 0.088 af | |
| Link 10L: Study Area Study Area WQ MTD A-110 (Total) | Primary=0.45 cfs 0.088 af Inflow=0.13 cfs 0.021 af | |
| Link 14L: Study Area West (Total) | Primary=0.13 cfs 0.021 af Inflow=2.42 cfs 0.311 af | |
| Link 16L: Study Area Basin A (Total) | Primary=2.42 cfs 0.311 af Inflow=0.05 cfs 0.014 af | |
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 72
Link 18L: Study Area Road Undetained (Total) Inflow=0.13 cfs 0.019 af
Primary=0.13 cfs 0.019 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.509 af Average Runoff Depth = 2.61"
62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
Page 58
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 73
Summary for Subcatchment 3S: Ex. Study Area West (Perv)
Runoff = 0.14 cfs @ 12.53 hrs, Volume= 0.042 af, Depth= 0.55"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total, Increased to minimum Tc = 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 10-Year-Projected Rainfall=6.34" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 74 |
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.36 cfs @ 12.19 hrs, Volume= 0.046 af, Depth= 6.10"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B
1.1 148 0.0200 2.28 Smooth surfaces n= 0.011 P2= 4.04"
Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
2.0 248 Total, Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
Page 59
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 75
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.12 cfs @ 12.19 hrs, Volume= 0.015 af, Depth= 6.10"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
1.0 82 0.0150 1.32 Sheet Flow, A-B Smooth surfaces n = 0.011 P2= 4.04"
1.0 82 Total, Increased to minimum Tc = 10.0 min
Subcatchment 6S: Ex. Study Area Road (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D 10-Year-Projected Rainfall=6.34" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 76 |
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
Runoff = 0.02 cfs @ 12.53 hrs, Volume= 0.005 af, Depth= 0.55"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
| Area (ac) | CN | Description |
|---|---|---|
| 0.120 | 39 | >75% Grass cover, Good, HSG A |
| 0.120 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 1.0 | 61 | 0.0100 1.06 |
| Sheet Flow, A-B | ||
| Smooth surfaces | n= 0.011 P2= 4.04" | |
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
Page 60
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 77
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 2.42 cfs @ 12.19 hrs, Volume= 0.310 af, Depth= 6.10" Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 78
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.00 cfs @ 12.53 hrs, Volume= 0.001 af, Depth= 0.55"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total. Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Page 61
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 79
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.12 cfs @ 12.19 hrs, Volume= 0.015 af, Depth= 6.10"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.4 35 0.0322 1.52 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
0.4 35 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Study Area Road Undetained (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D 10-Year-Projected Rainfall=6.34" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 80 |
Summary for Subcatchment 14S: Study Area West Undetained
Runoff = 0.05 cfs @ 12.53 hrs, Volume= 0.014 af, Depth= 0.55"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
| Area (ac) | CN | Description |
|---|---|---|
| 0.310 | 39 | >75% Grass cover, Good, HSG A |
| 0.310 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 2.7 | 48 | 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04" |
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
Page 62
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 81
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.44 cfs @ 12.19 hrs, Volume= 0.056 af, Depth= 6.10"
Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perim= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D 10-Year-Projected Rainfall=6.34" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 82 |
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff = 0.01 cfs @ 12.53 hrs, Volume= 0.004 af, Depth= 0.55" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
Page 63
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 83
Summary for Pond 21P: Basin A Routing (StormBrixx)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 5.95" for 10-Year-Projected event
Inflow = 2.86 cfs @ 12.19 hrs, Volume= 0.367 af
Outflow = 0.70 cfs @ 12.86 hrs, Volume= 0.367 af, Atten= 75%, Lag= 40.0 min
Discarded = 0.70 cfs @ 12.86 hrs, Volume= 0.367 af
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af
Routed to Link 14L : Study Area West (Total)
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 118.68' @ 12.86 hrs Surf.Area= 3,001 sf Storage= 3,445 cf
Plug-Flow detention time= 26.6 min calculated for 0.367 af (100% of inflow)
Center-of-Mass det. time= 26.6 min ( 782.3 - 755.7 )
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W x 94.88'L x 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50'/ 117.40' S= 0.0045'/' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.70 cfs @ 12.86 hrs HW=118.68' (Free Discharge)\n uparrow3=Exfiltration ( Controls 0.70 cfs) | |||
| Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge)\n uparrow1=Culvert ( Controls 0.00 cfs)\n uparrow2=Orifice ( Controls 0.00 cfs) | |||
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 84
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrix Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf
24 Chambers/Row x 3.95' Long = 94.88' Row Length
16 Rows x 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers x 22.7 cf = 8,728.7 cf Chamber Storage
384 Chambers x 23.4 cf = 8,998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af Overall Storage Efficiency = 97.0% Overall System Size = 94.88' x 31.63' x 3.00'
384 Chambers
333.3 cy Field
Page 64
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 85
Pond 21P: Basin A Routing (StormBrixx)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 86
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, | Inflow Depth = 1.04" for 10-Year-Projected event | |
|---|---|---|---|---|
| Inflow = | 0.45 cfs @ | 12.22 hrs, | Volume= 0.088 af | |
| Primary = | 0.45 cfs @ | 12.22 hrs, | Volume= 0.088 af, | Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
Page 65
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 87
Summary for Link 8L: Existing Study Area Road (Total)
| Inflow Area = | 0.150 ac, 20.00% Impervious, Inflow Depth = 1.66" for 10-Year-Projected event |
|---|---|
| Inflow = | 0.13 cfs @ 12.20 hrs, Volume= 0.021 af |
| Primary = | 0.13 cfs @ 12.20 hrs, Volume= 0.021 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 88
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Inflow Area = 0.630 ac, 96.83% Impervious, Inflow Depth = 5.93" for 10-Year-Projected event
Inflow = 2.42 cfs @ 12.19 hrs, Volume = 0.311 af
Primary = 2.42 cfs @ 12.19 hrs, Volume = 0.311 af, Atten = 0%, Lag = 0.0 min
Routed to Link 16L: Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Page 66
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 89
Summary for Link 14L: Study Area West (Total)
| Inflow Area = | 1.050 ac, 68.57% Impervious, Inflow Depth = 0.16" for 10-Year-Projected event |
|---|---|
| Inflow = | 0.05 cfs @ 12.53 hrs, Volume= 0.014 af |
| Primary = | 0.05 cfs @ 12.53 hrs, Volume= 0.014 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 90
Summary for Link 16L: Study Area Basin A (Total)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 5.95" for 10-Year-Projected event
Inflow = 2.86 cfs @ 12.19 hrs, Volume = 0.367 af
Primary = 2.86 cfs @ 12.19 hrs, Volume = 0.367 af, Atten = 0%, Lag = 0.0 min
Routed to Pond 21P: Basin A Routing (StormBrixx)
Routed to Pond 21P : Basin A Routing (StormBrixx)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
Hydrograph
Page 67
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2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 91
Summary for Link 18L: Study Area Road Undetained (Total)
| Inflow Area = | 0.120 ac, 25.00% Impervious, Inflow Depth = 1.94" for 10-Year-Projected event |
|---|---|
| Inflow = | 0.13 cfs @ 12.20 hrs, Volume= 0.019 af |
| Primary = | 0.13 cfs @ 12.20 hrs, Volume= 0.019 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 92
| Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points | ||
| Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN | ||
| Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method | ||
| Subcatchment3S: Ex. Study Area West | Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=1.83" Flow Length=98' Tc=10.0 min CN=39 Runoff=0.98 cfs 0.142 af | |
|---|---|---|
| Subcatchment4S: Ex. Study Area West | Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=9.24" Flow Length=248' Tc=10.0 min CN=98 Runoff=0.54 cfs 0.069 af | |
| Subcatchment6S: Ex. Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=9.24" Flow Length=82' Slope=0.0150'/' Tc=10.0 min CN=98 Runoff=0.18 cfs 0.023 af | |
| Subcatchment7S: Ex. Study Area Road | Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=1.83" Flow Length=61' Slope=0.0100'/' Tc=10.0 min CN=39 Runoff=0.13 cfs 0.018 af | |
| Subcatchment10S: Study Area WQ MTD | Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=9.24" Flow Length=352' Tc=10.0 min CN=98 Runoff=3.63 cfs 0.470 af | |
| Subcatchment11S: Study Area WQ MTD | Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=1.83" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.02 cfs 0.003 af | |
| Subcatchment12S: Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=9.24" Flow Length=35' Slope=0.0322'/' Tc=10.0 min CN=98 Runoff=0.18 cfs 0.023 af | |
| Subcatchment14S: Study Area West | Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=1.83" Flow Length=48' Slope=0.0850'/' Tc=10.0 min CN=39 Runoff=0.33 cfs 0.047 af | |
| Subcatchment15S: Study Area Roof (Imp) | Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=9.24" Flow Length=207' Slope=0.0100'/' Tc=10.0 min CN=98 Runoff=0.65 cfs 0.085 af | |
| Subcatchment19S: Study Area Road | Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=1.83" Flow Length=58' Slope=0.0300'/' Tc=10.0 min CN=39 Runoff=0.09 cfs 0.014 af | |
| Pond 21P: Basin A Routing (StormBrixx) Discarded=0.71 cfs | Peak Elev=119.50' Storage=5,809 cf Inflow=4.30 cfs 0.557 af 0.505 af Primary=0.62 cfs 0.052 af Outflow=1.33 cfs 0.557 af | |
| Link 5L: Ex Study Area West (Total) | Inflow=1.51 cfs 0.211 af Primary=1.51 cfs 0.211 af | |
| Link 8L: Existing Study Area Road (Total) | Inflow=0.30 cfs 0.041 af Primary=0.30 cfs 0.041 af | |
| Link 10L: Study Area Study Area WQ MTD A-110 (Total) | Inflow=3.65 cfs 0.473 af Primary=3.65 cfs 0.473 af | |
| Link 14L: Study Area West (Total) | Inflow=0.80 cfs 0.099 af Primary=0.80 cfs 0.099 af | |
| Link 16L: Study Area Basin A (Total) | Inflow=4.30 cfs 0.557 af | |
Link 16L: Study Area Basin A (Total) Inflow=4.30 cfs 0.557 af Primary=4.30 cfs 0.557 af
Page 68
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\textregistered 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 93
Link 18L: Study Area Road Undetained (Total) Inflow=0.27 cfs 0.037 af
Primary=0.27 cfs 0.037 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.895 af Average Runoff Depth = 4.59"
62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
2026-02 Existing and Proposed Prepared by Dynamic Engineering HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC NOAA 24-hr D 100-Year-Current Rainfall=9.48" Printed 2/10/2026 Page 94
Summary for Subcatchment 3S: Ex. Study Area West (Perv)
Runoff = 0.98 cfs @ 12.22 hrs, Volume= 0.142 af, Depth= 1.83"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total, Increased to minimum Tc= 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
Hydrograph
Page 69
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 95
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.54 cfs @ 12.19 hrs, Volume= 0.069 af, Depth= 9.24" Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B
1.1 148 0.0200 2.28 Smooth surfaces n= 0.011 P2= 4.04"
Shallow Concentrated Flow, B-C
Unpaved Kv= 16.1 fps
2.0 248 Total Increased to minimum Tc = 10.0 min
2.0 248 Total. Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 100-Year-Current | Rainfall=9.48'' |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 96 |
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.18 cfs @ 12.19 hrs, Volume= 0.023 af, Depth= 9.24"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
1.0 82 0.0150 1.32
Sheet Flow, A-B
Smooth surfaces n= 0.011
P2= 4.04"
1.0 82 Total, Increased to minimum Tc = 10.0 min
Subcatchment 6S: Ex. Study Area Road (Imp)
Page 70
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 97
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
Runoff = 0.13 cfs @ 12.22 hrs, Volume= 0.018 af, Depth= 1.83"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.120 39 >75% Grass cover, Good, HSG A
0.120 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
1.0 61 0.0100 1.06 Sheet Flow, A-B Smooth surfaces n = 0.011 P2= 4.04"
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 100-Year-Current Rainfall=9.48" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 98 |
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 3.63 cfs @ 12.19 hrs, Volume= 0.470 af, Depth= 9.24" Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total Increased to minimum Tc = 10.0 min
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Page 71
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 99
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.02 cfs @ 12.22 hrs, Volume= 0.003 af, Depth= 1.83"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perm= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total, Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 100-Year-Current | Rainfall=9.48'' |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 100 |
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.18 cfs @ 12.19 hrs, Volume= 0.023 af, Depth= 9.24" Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
0.4 35 0.0322 1.52
Sheet Flow, A-B
Smooth surfaces n= 0.011 P2= 4.04"
0.4 35 Total Increased to minimum Tc = 10.0 min
0.4 35 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Study Area Road Undetained (Imp)
Page 72
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 101
Summary for Subcatchment 14S: Study Area West Undetained
Runoff = 0.33 cfs @ 12.22 hrs, Volume= 0.047 af, Depth= 1.83"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.310 39 >75% Grass cover, Good, HSG A
0.310 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
2.7 48 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
| 2026-02 Existing and Proposed | NOAA 24-hr D | 100-Year-Current | Rainfall=9.48" |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 102 |
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.65 cfs @ 12.19 hrs, Volume= 0.085 af, Depth= 9.24" Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perm= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
Page 73
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 103
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff = 0.09 cfs @ 12.22 hrs, Volume= 0.014 af, Depth= 1.83"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 100-Year-Current Rainfall=9.48"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
| 4.8 | 58 | Total Increased to minimum Te = 10.0 min |
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D | 100-Year-Current | Rainfall=9.48″ |
|---|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 | |
| HydroCAD\circledR 10.20-8a s/n 08640 | © 2025 HydroCAD Software Solutions LLC | Page 104 |
Summary for Pond 21P: Basin A Routing (StormBrixx)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 9.04" for 100-Year-Current event |
|---|---|
| Inflow = | 4.30 cfs @ 12.19 hrs, Volume= 0.557 af |
| Outflow = | 1.33 cfs @ 12.73 hrs, Volume= 0.557 af, Atten= 69%, Lag= 32.5 min |
| Discarded = | 0.71 cfs @ 12.73 hrs, Volume= 0.505 af |
| Primary = | 0.62 cfs @ 12.73 hrs, Volume= 0.052 af |
| Routed to Link 14L: Study Area West (Total) | |
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 119.50' @ 12.73 hrs Surf.Area= 3,001 sf Storage= 5,809 cf
Plug-Flow detention time=37.4 min calculated for 0.557 af (100% of inflow) Center-of-Mass det. time=37.3 min (788.0 - 750.6)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W x 94.88'L x 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside = 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside = 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50' / 117.40' S= 0.0045'' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0'' Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.71 cfs @ 12.73 hrs HW=119.49' (Free Discharge) —3=Exfiltration ( Controls 0.71 cfs) | |||
| Primary OutFlow Max=0.62 cfs @ 12.73 hrs HW=119.49' (Free Discharge) —1=Culvert (Passes 0.62 cfs of 6.91 cfs potential flow) —2=Orifice (Orifice Controls 0.62 cfs @ 3.17 fps) | |||
Page 74
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 105
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx® SD)
Inside = 23.7" W x 36.0" H => 5.75 sf x 3.95' L = 22.7 cf
Outside = 23.7" W x 36.0" H => 5.93 sf x 3.95' L = 23.4 cf
24 Chambers/Row x 3.95' Long = 94.88' Row Length
16 Rows x 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers x 22.7 cf = 8.728.7 cf Chamber Storage
384 Chambers x 23.4 cf = 8.998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' x 31.63' x 3.00'
384 Chambers
333.3 cy Field
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 106
Pond 21P: Basin A Routing (StormBrixx)
Page 75
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 107
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, Inflow Depth = 2.49" for 100-Year-Current event |
|---|---|---|
| Inflow = | 1.51 cfs @ | 12.21 hrs, Volume= 0.211 af |
| Primary = | 1.51 cfs @ | 12.21 hrs, Volume= 0.211 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 108
Summary for Link 8L: Existing Study Area Road (Total)
| Inflow Area = | 0.150 ac, 20.00% Impervious, Inflow Depth = 3.32" for 100-Year-Current event |
|---|---|
| Inflow = | 0.30 cfs @ 12.21 hrs, Volume= 0.041 af |
| Primary = | 0.30 cfs @ 12.21 hrs, Volume= 0.041 af, Atten= 0%, Laq= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
Page 76
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 109
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Inflow Area = 0.630 ac, 96.83% Impervious, Inflow Depth = 9.00" for 100-Year-Current event
Inflow = 3.65 cfs @ 12.19 hrs, Volume = 0.473 af
Primary = 3.65 cfs @ 12.19 hrs, Volume = 0.473 af, Atten = 0%, Lag = 0.0 min
Routed to Link 16L : Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 Time (hours)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 110
Summary for Link 14L: Study Area West (Total)
Inflow Area = 1.050 ac, 68.57% Impervious, Inflow Depth = 1.14" for 100-Year-Current event
Inflow = 0.80 cfs @ 12.63 hrs, Volume= 0.099 af
Primary = 0.80 cfs @ 12.63 hrs, Volume= 0.099 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
Page 77
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 111
Summary for Link 16L: Study Area Basin A (Total)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 9.04" for 100-Year-Current event
Inflow = 4.30 cfs @ 12.19 hrs, Volume = 0.557 af
Primary = 4.30 cfs @ 12.19 hrs, Volume = 0.557 af, Atten = 0%, Lag = 0.0 min
Routed to Pond 21P: Basin A Routing (StormBrixx)
Routed to Pond 21P : Basin A Routing (StormBrixx)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 112
Summary for Link 18L: Study Area Road Undetained (Total)
| Inflow Area = | 0.120 ac, 25.00% Impervious, Inflow Depth = 3.69" for 100-Year-Current event |
|---|---|
| Inflow = | 0.27 cfs @ 12.20 hrs, Volume= 0.037 af |
| Primary = | 0.27 cfs @ 12.20 hrs, Volume= 0.037 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
Page 78
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 113
Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment3S: Ex. Study Area West Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=2.87"
Flow Length=98' Tc=10.0 min CN=39 Runoff=1.73 cfs 0.222 af
Subcatchment4S: Ex. Study Area West Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=11.17"
Flow Length=248' Tc=10.0 min CN=98 Runoff=0.64 cfs 0.084 af
Subcatchment6S: Ex. Study Area Road Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=11.17"
Flow Length=82' Slope=0.0150 /" Tc=10.0 min CN=98 Runoff=0.21 cfs 0.028 af
Subcatchment7S: Ex. Study Area Road Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=2.87"
Flow Length=61' Slope=0.0100 /" Tc=10.0 min CN=39 Runoff=0.22 cfs 0.029 af
Subcatchment10S: Study Area WQ MTD Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=11.17"
Flow Length=352' Tc=10.0 min CN=98 Runoff=4.37 cfs 0.568 af
Subcatchment11S: Study Area WQ MTD Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=2.87"
Flow Length=351' Tc=10.0 min CN=39 Runoff=0.04 cfs 0.005 af
Subcatchment12S: Study Area Road Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=11.17"
Flow Length=35' Slope=0.0322 /" Tc=10.0 min CN=98 Runoff=0.21 cfs 0.028 af
Subcatchment14S: Study Area West Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=2.87"
Flow Length=48' Slope=0.0850 /" Tc=10.0 min CN=39 Runoff=0.58 cfs 0.074 af
Subcatchment15S: Study Area Roof Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=11.17"
Flow Length=207' Slope=0.0100 /" Tc=10.0 min CN=98 Runoff=0.79 cfs 0.102 af
Subcatchment19S: Study Area Road Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=2.87"
Flow Length=58' Slope=0.0300 /" Tc=10.0 min CN=39 Runoff=0.17 cfs 0.022 af
Pond 21P: Basin A Routing (StormBrixx) Peak Elev=120.00' Storage=7,267 cf Inflow=5.20 cfs 0.675 af Discarded=0.71 cfs 0.572 af Primary=0.91 cfs 0.103 af Outflow=1.62 cfs 0.675 af
Link 5L: Ex Study Area West (Total) Inflow=2.37 cfs 0.306 af Primary=2.37 cfs 0.306 af
Link 8L: Existing Study Area Road (Total) Inflow=0.44 cfs 0.057 af Primary=0.44 cfs 0.057 af
Link 10L: Study Area Study Area WQ MTD A-110 (Total) Inflow=4.41 cfs 0.573 af Primary=4.41 cfs 0.573 af
Link 14L: Study Area West (Total) Inflow=1.22 cfs 0.177 af Primary=1.22 cfs 0.177 af
Link 16L: Study Area Basin A (Total) Inflow=5.20 cfs 0.675 af Primary=5.20 cfs 0.675 af
| 2026-02 Existing and Proposed | NOAA 24-hr D 100-Year-Projected Rainfall=11.41" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC | Page 114 |
Link 18L: Study Area Road Undetained (Total) Inflow=0.38 cfs 0.049 af
Inflow=0.38 cfs 0.049 af Primary=0.38 cfs 0.049 af
Total Runoff Area = 2.340 ac Runoff Volume = 1.161 af Average Runoff Depth = 5.95"
62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
Page 79
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 115
Summary for Subcatchment 3S: Ex. Study Area West (Perv)
Runoff = 1.73 cfs @ 12.21 hrs, Volume= 0.222 af, Depth= 2.87"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total, Increased to minimum Tc = 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
| 2026-02 Existing and Proposed | NOAA 24-hr D 100-Year-Projected Rainfall=11.41" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 116 |
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.64 cfs @ 12.19 hrs, Volume= 0.084 af, Depth=11.17"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.1 148 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
2.0 248 Total, Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
Hydrograph
Page 80
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 117
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.21 cfs @ 12.19 hrs, Volume= 0.028 af, Depth=11.17"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
1.0 82 0.0150 1.32 Sheet Flow, A-B Smooth surfaces n = 0.011 P2= 4.04"
1.0 82 Total, Increased to minimum Tc = 10.0 min
Subcatchment 6S: Ex. Study Area Road (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC Page 118
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
Runoff = 0.22 cfs @ 12.21 hrs, Volume= 0.029 af, Depth= 2.87"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
| Area (ac) | CN | Description |
|---|---|---|
| 0.120 | 39 | >75% Grass cover, Good, HSG A |
| 0.120 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 1.0 | 61 | 0.0100 1.06 |
| Sheet Flow, A-B | ||
| Smooth surfaces | ||
| n= 0.011 P2= 4.04" | ||
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
Page 81
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 119
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 4.37 cfs @ 12.19 hrs, Volume= 0.568 af, Depth=11.17"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 120
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.04 cfs @ 12.21 hrs, Volume= 0.005 af, Depth= 2.87"
Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total. Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
Page 82
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 121
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.21 cfs @ 12.19 hrs, Volume= 0.028 af, Depth=11.17"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.4 35 0.0322 1.52 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
0.4 35 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Study Area Road Undetained (Imp)
| 2026-02 Existing and Proposed | NOAA 24-hr D 100-Year-Projected Rainfall=11.41" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC | Page 122 |
Summary for Subcatchment 14S: Study Area West Undetained
Runoff = 0.58 cfs @ 12.21 hrs, Volume= 0.074 af, Depth= 2.87"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
| Area (ac) | CN | Description |
|---|---|---|
| 0.310 | 39 | >75% Grass cover, Good, HSG A |
| 0.310 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 2.7 | 48 | 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04" |
| 3.7 | 48 | Total Increased to minimum Te = 10.0 min |
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
Page 83
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 123
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.79 cfs @ 12.19 hrs, Volume= 0.102 af, Depth=11.17"
Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
0.8 207 0.0100 4.50 1.57
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC Page 124
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff = 0.17 cfs @ 12.21 hrs, Volume= 0.022 af, Depth= 2.87"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
Runoff
Page 84
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 125
Summary for Pond 21P: Basin A Routing (StormBrixx)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 10.94" for 100-Year-Projected event
Inflow = 5.20 cfs @ 12.19 hrs, Volume= 0.675 af
Outflow = 1.62 cfs @ 12.72 hrs, Volume= 0.675 af, Atten= 69%, Lag= 32.1 min
Discarded = 0.71 cfs @ 12.72 hrs, Volume= 0.572 af
Primary = 0.91 cfs @ 12.72 hrs, Volume= 0.103 af
Routed to Link 14L : Study Area West (Total)
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 120.00' @ 12.72 hrs Surf.Area= 3,001 sf Storage= 7,267 cf
Plug-Flow detention time= 40.1 min calculated for 0.675 af (100% of inflow)
Center-of-Mass det. time= 40.1 min ( 788.9 - 748.8 )
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W x 94.88'L x 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf x 40.0% Voids ACO StormBrixx SD 1 x 384 Inside #1 Inside= 23.7"W x 36.0"H => 5.75 sf x 3.95'L = 22.7 cf Outside= 23.7"W x 36.0"H => 5.93 sf x 3.95'L = 23.4 cf 384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50'/ 117.40' S= 0.0045'/' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.71 cfs @ 12.72 hrs HW=119.99' (Free Discharge) —3=Exfiltration ( Controls 0.71 cfs) | |||
| Primary OutFlow Max=0.91 cfs @ 12.72 hrs HW=119.99' (Free Discharge) —1=Culvert (Passes 0.91 cfs of 8.73 cfs potential flow) —2=Orifice (Orifice Controls 0.91 cfs @ 4.66 fps) | |||
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 126
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx SD)
Inside = 23.7" W × 36.0" H => 5.75 sf × 3.95' L = 22.7 cf
Outside = 23.7" W × 36.0" H => 5.93 sf × 3.95' L = 23.4 cf
24 Chambers/Row × 3.95' Long = 94.88' Row Length
16 Rows × 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers × 22.7 cf = 8,728.7 cf Chamber Storage
384 Chambers × 23.4 cf = 8,998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' × 31.63' × 3.00'
384 Chambers
333.3 cy Field
Page 85
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 127
Pond 21P: Basin A Routing (StormBrixx)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 128
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, Inflow Depth = 3.60" for 100-Year-Projected event |
|---|---|---|
| Inflow = | 2.37 cfs @ | 12.21 hrs, Volume= 0.306 af |
| Primary = | 2.37 cfs @ | 12.21 hrs, Volume= 0.306 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 129
Summary for Link 8L: Existing Study Area Road (Total)
Inflow Area = 0.150 ac, 20.00% Impervious, Inflow Depth = 4.53" for 100-Year-Projected event
Inflow = 0.44 cfs @ 12.20 hrs, Volume = 0.057 af
Primary = 0.44 cfs @ 12.20 hrs, Volume = 0.057 af, Atten = 0%, Lag = 0.0 min
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 130
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
| Inflow Area = | 0.630 ac, 96.83% Impervious, Inflow Depth = 10.91" for 100-Year-Projected event |
|---|---|
| Inflow = | 4.41 cfs @ 12.19 hrs, Volume= 0.573 af |
| Primary = | 4.41 cfs @ 12.19 hrs, Volume= 0.573 af, Atten= 0%, Lag= 0.0 min |
| Routed to Link 16L : Study Area Basin A (Total) | |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Page 87
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 131
Summary for Link 14L: Study Area West (Total)
| Inflow Area = | 1.050 ac, 68.57% Impervious, Inflow Depth = 2.02" for 100-Year-Projected event |
|---|---|
| Inflow = | 1.22 cfs @ 12.55 hrs, Volume= 0.177 af |
| Primary = | 1.22 cfs @ 12.55 hrs, Volume= 0.177 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 132
Summary for Link 16L: Study Area Basin A (Total)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 10.94" for 100-Year-Projected event
Inflow = 5.20 cfs @ 12.19 hrs, Volume = 0.675 af
Primary = 5.20 cfs @ 12.19 hrs, Volume = 0.675 af, Atten = 0%, Lag = 0.0 min
Routed to Bond 21P: Basin A Routing (StormBrixx)
Routed to Pond 21P : Basin A Routing (StormBrixx)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
Hydrograph
Page 88
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2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 133
Summary for Link 18L: Study Area Road Undetained (Total)
Inflow Area = 0.120 ac, 25.00% Impervious, Inflow Depth = 4.94" for 100-Year-Projected event
Inflow = 0.38 cfs @ 12.20 hrs, Volume = 0.049 af
Primary = 0.38 cfs @ 12.20 hrs, Volume = 0.049 af, Atten = 0%, Lag = 0.0 min
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
Page 89
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HYDROGRAPH SUMMARY REPORTS – WATER QUALITY STORM
Page 90
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Project Notes
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NRCS-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Defined 1 rainfall events from NJ-DEP IDF
Defined 1 rainfall events from NJ-DEP IDF
Printed 2/10/2026
Page 2
Page 91
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Rainfall Events Listing (selected events)
2026-02 Existing and Proposed Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 3
Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC
1 WQ NJ DEP 2-hr Default 2.00 1 1.24 2
| 2026-02 Existing and Proposed | |
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
|---|---|
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 4 |
026-02 Existing and Proposed
Prepared by Dynamic Engineering Printed 2/10/2026 hydroCAD\textregistered 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 3
| Area Listing (selected nodes) | ||
| Area (acres) | CN | Description (subcatchment-numbers) |
|---|---|---|
| 1.470 | 39 | >75% Grass cover, Good, HSG A (3S, 7S, 11S, 14S, 19S) |
| 0.710 | 98 | Paved parking, HSG A (4S, 6S, 10S, 12S) |
| 0.160 | 98 | Roofs, HSG A (4S, 15S) |
| 2.340 | 61 | TOTAL AREA |
Page 92
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2026-02 Existing and Proposed Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 5 2026-02 Existing and Proposed Prepared by Dynamic Engineering
HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Soil Listing (selected nodes) Ground Covers (selected nodes)
Area (acres) Soil Group Subcatchment Numbers HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers
2.340 HSG A 3S, 4S, 6S, 7S, 10S, 11S, 12S, 14S, 15S, 19S 1.470 0.000 0.000 0.000 0.000 1.470 >75% Grass cover, Good
0.000 HSG B 3S, 7S, 11S,
0.000 HSG C 14S,
0.000 HSG D 19S
0.000 Other 4S, 6S,
2.340 TOTAL AREA 0.710 0.000 0.000 0.000 0.000 0.710 Paved parking 10S, 12S
0.160 0.000 0.000 0.000 0.000 0.160 Roofs 4S, 15S
2.340 0.000 0.000 0.000 0.000 2.340 TOTAL AREA
Page 93
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Printed 2/10/2026
Page 7
Pipe Listing (selected nodes)
| Line# | Node Number | In-Invert (feet) | Out-Invert (feet) | Length (feet) | Slope (ft/ft) | n | Width (inches) | Diam/Height (inches) | Inside-Fill (inches) | Node Name |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 10S | 0.00 | 0.00 | 297.0 | 0.0035 | 0.011 | 0.0 | 15.0 | 0.0 | |
| 2 | 11S | 0.00 | 0.00 | 297.0 | 0.0035 | 0.011 | 0.0 | 15.0 | 0.0 | |
| 3 | 15S | 0.00 | 0.00 | 207.0 | 0.0100 | 0.010 | 0.0 | 8.0 | 0.0 | |
| 4 | 21P | 117.50 | 117.40 | 22.0 | 0.0045 | 0.013 | 0.0 | 15.0 | 0.0 |
2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
NJ DEP 2-hr WQ Rainfall=1.24"
Printed 2/10/2026
Page 8
| Time span=0.00-72.00 hrs, dt=0.03 hrs, 1441 points | ||
| Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN | ||
| Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method | ||
| Subcatchment3S: Ex. Study Area West | Runoff Area=0.930 ac 0.00% Impervious Runoff Depth=0.00" Flow Length=98' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
|---|---|---|
| Subcatchment4S: Ex. Study Area West | Runoff Area=0.090 ac 100.00% Impervious Runoff Depth=1.02" Flow Length=248' Tc=10.0 min CN=98 Runoff=0.17 cfs 0.008 af | |
| Subcatchment6S: Ex. Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=1.02" Flow Length=82' Slope=0.0150 1/'' Tc=10.0 min CN=98 Runoff=0.06 cfs 0.003 af | |
| Subcatchment7S: Ex. Study Area Road | Runoff Area=0.120 ac 0.00% Impervious Runoff Depth=0.00" Flow Length=61' Slope=0.0100 1/'' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment10S: Study Area WQ MTD | Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=1.02" Flow Length=352' Tc=10.0 min CN=98 Runoff=1.12 cfs 0.052 af | |
| Subcatchment11S: Study Area WQ MTD | Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=0.00" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment12S: Study Area Road | Runoff Area=0.030 ac 100.00% Impervious Runoff Depth=1.02" Flow Length=35' Slope=0.0322 1/'' Tc=10.0 min CN=98 Runoff=0.06 cfs 0.003 af | |
| Subcatchment14S: Study Area West | Runoff Area=0.310 ac 0.00% Impervious Runoff Depth=0.00" Flow Length=48' Slope=0.0850 1/'' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Subcatchment15S: Study Area Roof (Imp) | Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=1.02" Flow Length=207' Slope=0.0100 1/'' Tc=10.0 min CN=98 Runoff=0.20 cfs 0.009 af | |
| Subcatchment19S: Study Area Road | Runoff Area=0.090 ac 0.00% Impervious Runoff Depth=0.00" Flow Length=58' Slope=0.0300 1/'' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.000 af | |
| Pond 21P: Basin A Routing (StormBrixx) Discarded=0.70 cfs | Peak Elev=117.70' Storage=580 cf Inflow=1.33 cfs 0.061 af 0.061 af Primary=0.00 cfs 0.000 af Outflow=0.70 cfs 0.061 af | |
| Link 5L: Ex Study Area West (Total) | Inflow=0.17 cfs 0.008 af Primary=0.17 cfs 0.008 af | |
| Link 8L: Existing Study Area Road (Total) | Inflow=0.06 cfs 0.003 af Primary=0.06 cfs 0.003 af | |
| Link 10L: Study Area Study Area WQ MTD A-110 (Total) | Inflow=1.12 cfs 0.052 af Primary=1.12 cfs 0.052 af | |
| Link 14L: Study Area West (Total) | Inflow=0.00 cfs 0.000 af Primary=0.00 cfs 0.000 af | |
| Link 16L: Study Area Basin A (Total) | Inflow=1.33 cfs 0.061 af Primary=1.33 cfs 0.061 af | |
Page 94
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2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 9
Link 18L: Study Area Road Undetained (Total) Inflow=0.06 cfs 0.003 af
Primary=0.06 cfs 0.003 af
Total Runoff Area = 2.340 ac Runoff Volume = 0.074 af Average Runoff Depth = 0.38"
62.82% Pervious = 1.470 ac 37.18% Impervious = 0.870 ac
2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment 3S: Ex. Study Area West (Perv)
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.930 39 >75% Grass cover, Good, HSG A
0.930 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
8.4 47 0.0350 0.09 Sheet Flow, A-B Woods: Light underbrush n= 0.400 P2= 4.04" Using McCuen-Spiess flow length
0.4 51 0.0200 2.28 Shallow Concentrated Flow, B-C Unpaved Kv= 16.1 fps
8.8 98 Total. Increased to minimum Tc = 10.0 min
Subcatchment 3S: Ex. Study Area West (Perv)
Runoff
Page 95
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2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 4S: Ex. Study Area West (Imp)
Runoff = 0.17 cfs @ 1.17 hrs, Volume= 0.008 af, Depth= 1.02" Routed to Link 5L : Ex Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.040 98 Paved parking, HSG A
0.050 98 Roofs, HSG A
0.090 98 Weighted Average
0.090 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.9 100 0.0300 1.82 Sheet Flow, A-B
1.1 148 0.0200 2.28 Smooth surfaces n= 0.011 P2= 4.04"
Shallow Concentrated Flow, B-C
Unpaved Kv= 16.1 fps
2.0 248 Total Increased to minimum Tc = 10.0 min
2.0 248 Total, Increased to minimum Tc = 10.0 min
Subcatchment 4S: Ex. Study Area West (Imp)
| 2026-02 Existing and Proposed | NJ DEP 2-hr WQ Rainfall=1.24" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 12 |
Summary for Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff = 0.06 cfs @ 1.17 hrs, Volume= 0.003 af, Depth= 1.02"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.030 98 Paved parking, HSG A
0.030 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec)
1.0 82 0.0150 1.32
Sheet Flow, A-B
Smooth surfaces n= 0.011 P2= 4.04"
1.0 82 Total. Increased to minimum
Subcatchment 6S: Ex. Study Area Road (Imp)
Runoff
Page 96
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2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 7S: Ex. Study Area Road (Perv)
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Routed to Link 8L : Existing Study Area Road (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
| Area (ac) | CN | Description |
|---|---|---|
| 0.120 | 39 | >75% Grass cover, Good, HSG A |
| 0.120 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 1.0 | 61 | 0.0100 1.06 |
| Sheet Flow, A-B | ||
| Smooth surfaces | n= 0.011 P2= 4.04" | |
1.0 61 Total, Increased to minimum Tc = 10.0 min
Subcatchment 7S: Ex. Study Area Road (Perv)
| 2026-02 Existing and Proposed | NJ DEP 2-hr WQ Rainfall=1.24" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 14 |
Summary for Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
Runoff = 1.12 cfs @ 1.17 hrs, Volume= 0.052 af, Depth= 1.02" Routed to Link 10L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 10S: Study Area WQ MTD A-110 (Imp)
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2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 15
Summary for Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Routed to Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perm= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total, Increased to minimum Tc = 10.0 min
Subcatchment 11S: Study Area WQ MTD A-110 (Perv)
2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC Page 16
Summary for Subcatchment 12S: Study Area Road Undetained (Imp)
Runoff = 0.06 cfs @ 1.17 hrs, Volume= 0.003 af, Depth= 1.02"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff = 0.06 cfs @ 1.17 hrs, Volume= 0.003 af, Depth= 1.02"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Page 98
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2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 17
Summary for Subcatchment 14S: Study Area West Undetained
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Routed to Link 14L : Study Area West (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.310 39 >75% Grass cover, Good, HSG A
0.310 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
2.7 48 0.0850 0.29 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
2.7 48 Total, Increased to minimum Tc = 10.0 min
Subcatchment 14S: Study Area West Undetained
2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC Page 18
Summary for Subcatchment 15S: Study Area Roof (Imp)
Runoff = 0.20 cfs @ 1.17 hrs, Volume= 0.009 af, Depth= 1.02" Routed to Link 16L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perm= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 15S: Study Area Roof (Imp)
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2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\circledR 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC Page 19
Summary for Subcatchment 19S: Study Area Road Undetained (Perv)
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00"
Routed to Link 18L : Study Area Road Undetained (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NJ DEP 2-hr WQ Rainfall=1.24"
| Area (ac) | CN | Description |
|---|---|---|
| 0.090 | 39 | >75% Grass cover, Good, HSG A |
| 0.090 | 39 | 100.00% Pervious Area |
| Tc (min) | Length (feet) | Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) |
| 4.8 | 58 | 0.0300 0.20 |
| Sheet Flow, A-B | ||
| Grass: Short n= 0.150 P2= 4.04" | ||
| 4.8 | 58 | Total Increased to minimum Tc = 10.0 min |
4.8 58 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area Road Undetained (Perv)
| 2026-02 Existing and Proposed | NJ DEP 2-hr | WQ Rainfall=1.24" |
|---|---|---|
| Prepared by Dynamic Engineering | Printed | 2/10/2026 |
| HydroCAD\circledR 10.20-8a s/n 08640\circledC 2025 HydroCAD Software Solutions LLC | Page 20 |
Summary for Pond 21P: Basin A Routing (StormBrixx)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 1.00" for WQ event | ||
|---|---|---|---|
| Inflow = | 1.33 cfs @ | 1.17 hrs, Volume= | 0.061 af |
| Outflow = | 0.70 cfs @ | 1.43 hrs, Volume= | 0.061 af, Atten= 48%, Lag= 15.3 min |
| Discarded = | 0.70 cfs @ | 1.43 hrs, Volume= | 0.061 af |
| Primary = | 0.00 cfs @ | 0.00 hrs, Volume= | 0.000 af |
| Routed to Link 14L : Study Area West (Total) | |||
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 117.70' @ 1.43 hrs Surf.Area= 3,001 sf Storage= 580 cf
Plug-Flow detention time=7.8 min calculated for 0.061 af (100% of inflow) Center-of-Mass det. time=7.8 min (87.9 - 80.1)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W × 94.88'L × 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf × 40.0% Voids\nACO StormBrixx SD 1 × 384 Inside #1\nInside= 23.7"W × 36.0"H => 5.75 sf × 3.95'L = 22.7 cf\nOutside= 23.7"W × 36.0"H => 5.93 sf × 3.95'L = 23.4 cf\n384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50' / 117.40' S= 0.0045'' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0'' Vert. Orifice C= 0.600 Limited to weir flow at low heads |
| #3 | Discarded | 117.50' | 10.000 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = -4.00' |
| Discarded OutFlow Max=0.70 cfs @ 1.43 hrs HW=117.70' (Free Discharge) —3=Exfiltration ( Controls 0.70 cfs) | |||
| Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=117.50' (Free Discharge) —1=Culvert ( Controls 0.00 cfs) —2=Orifice ( Controls 0.00 cfs) | |||
Page 100
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
NJ DEP 2-hr WQ Rainfall=1.24"
Printed 2/10/2026
Page 21
Pond 21P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx® SD)
Inside = 23.7" W × 36.0" H => 5.75 sf × 3.95' L = 22.7 cf
Outside = 23.7" W × 36.0" H => 5.93 sf × 3.95' L = 23.4 cf
24 Chambers/Row x 3.95' Long = 94.88' Row Length
16 Rows x 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers x 22.7 cf = 8.728.7 cf Chamber Storage
384 Chambers x 23.4 cf = 8.998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' x 31.63' x 3.00'
384 Chambers
333.3 cy Field
2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
NJ DEP 2-hr WQ Rainfall=1.24"
Printed 2/10/2026
Page 22
Pond 21P: Basin A Routing (StormBrixx)
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 Time (hours)
Inflow Outflow Discarded Primary
Page 101
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
NJ DEP 2-hr WQ Rainfall=1.24"
Printed 2/10/2026
Page 23
Summary for Link 5L: Ex Study Area West (Total)
| Inflow Area = | 1.020 ac, | 8.82% Impervious, Inflow Depth = 0.09" for WQ event |
|---|---|---|
| Inflow = | 0.17 cfs @ | 1.17 hrs, Volume= 0.008 af |
| Primary = | 0.17 cfs @ | 1.17 hrs, Volume= 0.008 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 5L: Ex Study Area West (Total)
2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.2
Prepared by Dynamic Engineering Printed 2/10/202
HydroCAD\circledR 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 2
Summary for Link 8L: Existing Study Area Road (Total)
| Inflow Area = | 0.150 ac, 20.00% Impervious, Inflow Depth = 0.20" for WQ event | ||
| Inflow = | 0.06 cfs @ | 1.17 hrs, Volume= | 0.003 af |
|---|---|---|---|
| Primary = | 0.06 cfs @ | 1.17 hrs, Volume= | 0.003 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 8L: Existing Study Area Road (Total)
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
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NJ DEP 2-hr WQ Rainfall=1.24"
Printed 2/10/2026
Page 25
Summary for Link 10L: Study Area Study Area WQ MTD A-110 (Total)
Inflow Area = 0.630 ac, 96.83% Impervious, Inflow Depth = 0.99" for WQ event
Inflow = 1.12 cfs @ 1.17 hrs, Volume = 0.052 af
Primary = 1.12 cfs @ 1.17 hrs, Volume = 0.052 af, Atten = 0%, Lag = 0.0 min
Routed to Link 16L : Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 10L: Study Area Study Area WQ MTD A-110 (Total)
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 Time (hours)
2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\textregistered 10.20-8a s/n 08640\circledR 2025 HydroCAD Software Solutions LLC
Summary for Link 14L: Study Area West (Total)
| Inflow Area = | 1.050 ac, 68.57% Impervious, Inflow Depth = 0.00" for WQ event |
|---|---|
| Inflow = | 0.00 cfs @ 0.00 hrs, Volume= 0.000 af |
| Primary = | 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 14L: Study Area West (Total)
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2026-02 Existing and Proposed
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
NJ DEP 2-hr WQ Rainfall=1.24"
Printed 2/10/2026
Page 27
Summary for Link 16L: Study Area Basin A (Total)
| Intlow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 1.00" for WQ event |
|---|---|
| Inflow = | 1.33 cfs @ 1.17 hrs, Volume= 0.061 af |
| Primary = | 1.33 cfs @ 1.17 hrs, Volume= 0.061 af, Atten= 0%, Lag= 0.0 min |
| Routed to Pond 21P : Basin A Routing (StormBrixx) | |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 16L: Study Area Basin A (Total)
2026-02 Existing and Proposed NJ DEP 2-hr WQ Rainfall=1.24"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD\textregistered 10.20-8a s/n 08640\circledR 2025 Page 28
Summary for Link 18L: Study Area Road Undetained (Total)
| Inflow Area = | 0.120 ac, 25.00% Impervious, Inflow Depth = 0.26" for WQ event | ||
| Inflow = | 0.06 cfs @ | 1.17 hrs, Volume= | 0.003 af |
|---|---|---|---|
| Primary = | 0.06 cfs @ | 1.17 hrs, Volume= | 0.003 af, Atten= 0%, Lag= 0.0 min |
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 18L: Study Area Road Undetained (Total)
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HYDROGRAPH COMPARISON – STUDY AREA ROAD
UNDETAINED 2, 10 & 100-YEAR
Page 105
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NOAA 24-hr D 2-Year-Current Rainfall=3.42"
Printed 2/10/2026
2026-02 Existing and Proposed NOAA 24-hr
Prepared by Dynamic Engineering
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Primary Comparison
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NOAA 24-hr D 2-Year-Projected Rainfall=4.04"
Printed 2/10/2026
2026-02 Existing and Proposed NOAA 24-hr D
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Primary Comparison
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NOAA 24-hr D 10-Year-Current Rainfall=5.38"
Printed 2/10/2026
2026-02 Existing and Proposed NOAA 24-hr D
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Primary Comparison
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Primary (cfs)
Primary Comparison
2026-02 Existing and Proposed NOAA 24-hr D 10-Year-Projected Rainfall=6.34"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
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NOAA 24-hr D 100-Year-Current Rainfall=9.48"
Printed 2/10/2026
2026-02 Existing and Proposed NOAA 24-hr D
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Primary Comparison
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Link 8L
Link 18L
Primary Comparison
Primary (cfs)
2026-02 Existing and Proposed NOAA 24-hr D 100-Year-Projected Rainfall=11.41"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
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STORMWATER COLLECTION SYSTEM
CALCULATIONS (PIPE SIZING)
Page 112
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Stormwater Collection System Calculations
NOTES:
Project: Proposed Office Building Job #: 3342-99-007 Location: Jackson, NJ Design Storm: 25 yr NJDEP Computed By: NC Checked By: RTO Date: 2/13/2026 Last Revised: 1) Design method used is Rational Method, unless otherwise noted. 2) Refer to Weighted Runoff Coefficient table for calculation of incremental areas and C values
Start Node INLET A-310 OCS A-100 INLET A-203 INLET A-220 INLET A-210 INLET A-200 INLET A-200 INLET A-210 Stop Node MTD 15" FES INLET A-210 INLET A-210 Upstream Inlet Area (acres) 0.10 (N/A) 0.10 0.10 0.10 0.10 0.10 System Intensity (in/h) 7.045 8.020 7.700 7.700 7.507 7.143 7.365 Upstream Inlet Tc (hours) 0.100 0.000 0.100 0.100 0.100 Flow (cfs) 4.18 3.02 0.72 0.72 1.56 3.57 1.39 Capacity (Full Flow) (cfs) 6.21 4.44 3.82 3.82 3.82 Velocity (Out) (ft/s) 4.48 4.28 1.39 1.25 1.57 3.94 1.40 Diameter (in) 18 15 15 15 15 15 Section Type Circle Circle Concrete 0.013 0.013 0.013 0.013 0.013 Material 0.013 0.013 0.013 0.013 0.013 Manning's n 17 22 152 87 132 91 147 Length (ft) 0.0035 0.0050 0.0035 0.0035 0.0035 Slope (ft/ft) 118.37 117.50 119.73 119.45 119.15 118.69 118.69 119.20 Start Invert (ft) 118.31 117.40 119.20 119.15 118.31 118.26 120.10 119.83 119.75 119.63 119.63 HGL In (ft) 119.23 118.10 119.75 119.75 HGL Out (ft) 119.09 118.10 119.75 119.75
Page 113
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CONDUIT OUTLET PROTECTION CALCULATIONS
Page 114
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D DYNAMIC ENGINEERING
Preformed Scour Hole Design
| Project: | Proposed Office Building |
|---|---|
| Job #: | 3342-99-007 |
| Location: | Jackson, NJ |
| Design Storm: | 25-Year |
| Computed By: | NC |
| Checked By: | |
| Date: | 2/10/2026 |
Discharge not in Basin, Therefore Tailwater is less than 0.5 x Do
| Discharge Point ID | POI AREA WEST |
|---|---|
| Q (25-yr storm cfs) | 0.7 |
| Inside Height of Outlet Culvert, Do (in) | 15 |
| Inside Height of Outlet Culvert, Do (ft) | 1.3 |
| Tailwater (ft), TW | 0.25 |
| Bottom Length of Scour Hole, L1=3 Do (ft) | 3.75 |
| Width of Culvert, Wo (in) | 15 |
| Width of Culvert, Wo (ft) | 1.3 |
| Bottom Width of Scour Hole, W1=2 Wo (ft) | 2.50 |
When using Y = (.5)(Do):
| Where Y = .5 Do, Y(ft) | 0.625 |
|---|---|
| Median Stone Diameter*, D50 (ft) | 0.02 |
| Overall Length of Scour Hole, L2 (ft) | 7.50 |
| Overall Width of Scour Hole, W2 (ft) | 6.25 |
When using Y = (D0):
| Where Y = Do, Y(ft) | 1.250 |
|---|---|
| Median Stone Diameter*, D50 (ft) | 0.02 |
| Overall Length of Scour Hole, L2 (ft) | 11.25 |
| Overall Width of Scour Hole, W2 (ft) | 10.00 |
Use D50 equal to 6 inches
Use D50 equal to 6 inches
Equations used:
Tw=0.2*Do (If Tw cannot be computed)
Where Y=1/2 Do
D50=(0.0125/Tw)*(q^1.33)
Where Y=Do
D50=(0.0082/Tw)*(q^1.33)
Notes: ___
The use of scour holes shall comply with county or local ordinances which would restrict the use of such devices due to the possible problems with mosquito breeding.
No bends or curves at the intersection of the conduit and apron or scour hole will be permitted.
There shall be no overfall from the end of the apron to the receiving material.
The thickness of the riprap lining, filter, and quality shall meet the requirements in the Riprap Standard Section of the Standards for Soil Erosion Control in New Jersey.
Use a D50 of 6 inches minimum.
Page 115
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GROUNDWATER RECHARGE CALCULATION
Page 116
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Pinelands Net Impervious 10 Year Infiltration Calculations
Page 117
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GROUNDWATER MOUNDING CALCULATIONS
Page 118
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Input Values
10.00 R Recharge rate (permeability rate) (in/hr) Specific yield, Sy (dimensionless)
0.150 Sy default value is 0.15; max value is 0.2 provided that a lab test data is submitted Horizontal hydraulic conductivity (in/hr)
50.00 Kh Kh = 5xRecharge Rate (R) in the costal plan; Kh=R outside the coastal plan
47.500 x 1/2 length of basin (x direction, in feet)
16.000 y 1/2 width of basin (y direction, in feet)
6.74 t Duration of infiltration period (hours)
10.00 hi(0) Initial thickness of saturated zone (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.
Page 119
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BASIN DRAIN TIME CALCULATIONS
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Infiltration Basin Drain time Calculations
| Project: | Proposed Office Building | Computed By: |
|---|---|---|
| Job #: | 3342-99-007 | Checked By: |
| Location: | Jackson, NJ | Date: |
NC
8/9/23
Revised:
02/10/2026
Basin Name: Prop. StormBrixx
Effective Depth of Runoff to be Infiltrated = Volume of Runoff to be Infiltrated / Surface Area of Infiltration Area = 7,267 cubic feet
3,040 square feet
2.39 feet
20 inches per hour
10 inches per hour
Effective Depth of Runoff to be Infiltrated / Design Recharge Rate = Time to Empty Basin =
2.87 hours**
*Note : Factor of Safety of 2 is applied to the Field Tested Recharge Rate to establish the Design Recharge Rate**Note : Time to Empty Basin must be less than 72 hours. Therefore; Drain time is less than 72 Hours, therefore, design is acceptable
Page 121
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OFFSITE STABILITY FAILURE ANALYSIS
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Routing Diagram for 2026-02 Offsite Stability
Prepared by Dynamic Engineering, Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
2026-02 Offsite Stability
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Project Notes
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NRCS-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Defined 1 rainfall events from NJ-DEP IDF
Defined 1 rainfall events from NJ-DEP IDF
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Rainfall events imported from "NJ-Rain.txt" for 6614 NJ Ocean-D
Printed 2/10/2026
Page 2
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Rainfall Events Listing (selected events)
Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC P2 (inches)
1 25-Year NOAA 24-hr D Default 24.00 1 6.68 2 4.04
| 2026-02 Offsite Stability | |
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
|---|---|
| HydroCAD\textregistered 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC | Page 4 |
| Area Listing (selected nodes) | ||
| Area (acres) | CN | Description (subcatchment-numbers) |
|---|---|---|
| 0.020 | 39 | >75% Grass cover, Good, HSG A (19S) |
| 0.610 | 98 | Paved parking, HSG A (18S) |
| 0.110 | 98 | Roofs, HSG A (16S) |
| 0.740 | 96 | TOTAL AREA |
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2026-02 Offsite Stability
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Printed 2/10/2026
Page 5
2026-02 Offsite Stability
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Printed 2/10/2026
Page 6
Soil Listing (selected nodes)
Ground Covers (selected nodes)
| Area (acres) | Soil Group | Subcatchment Numbers | HSG-A (acres) | HSG-B (acres) | HSG-C (acres) | HSG-D (acres) | Other (acres) | Total (acres) | Ground Cover | Subcatchment Numbers |
|---|---|---|---|---|---|---|---|---|---|---|
| 0.740 | HSG A | 16S, 18S, 19S | 0.020 | 0.000 | 0.000 | 0.000 | 0.000 | 0.020 | >75% Grass cover, Good | 19S |
| 0.000 | HSG B | 0.610 | 0.000 | 0.000 | 0.000 | 0.000 | 0.610 | Paved parking | 18S | |
| 0.000 | HSG C | 0.110 | 0.000 | 0.000 | 0.000 | 0.000 | 0.110 | Roofs | 16S | |
| 0.000 | HSG D | 0.740 | 0.000 | 0.000 | 0.000 | 0.000 | 0.740 | TOTAL AREA | ||
| 0.000 | Other | |||||||||
| 0.740 | TOTAL AREA |
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2026-02 Offsite Stability
Prepared by Dynamic Engineering
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC
Printed 2/10/2026
Page 7
| Pipe Listing (selected nodes) | ||||||||||
| Line# | Node Number | In-Invert (feet) | Out-Invert (feet) | Length (feet) | Slope (ft/ft) | n | Width (inches) | Diam/Height (inches) | Inside-Fill (inches) | Node Name |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 16S | 0.00 | 0.00 | 207.0 | 0.0100 | 0.010 | 0.0 | 8.0 | 0.0 | |
| 2 | 18S | 0.00 | 0.00 | 297.0 | 0.0035 | 0.011 | 0.0 | 15.0 | 0.0 | |
| 3 | 19S | 0.00 | 0.00 | 297.0 | 0.0035 | 0.011 | 0.0 | 15.0 | 0.0 | |
| 4 | 17P | 117.50 | 117.40 | 22.0 | 0.0045 | 0.013 | 0.0 | 15.0 | 0.0 | |
2026-02 Offsite Stability NOAA 24-nt D 25-Year Rainfall=0.68 , P2=4.04
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 8
Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment16S: Study Area Roof (Imp) Runoff Area=0.110 ac 100.00% Impervious Runoff Depth=6.44" Flow Length=207' Slope=0.0100 /" Tc=10.0 min CN=98 Runoff=0.46 cfs 0.059 af
Subcatchment18S: Study Area WQ MTD Runoff Area=0.610 ac 100.00% Impervious Runoff Depth=6.44" Flow Length=352' Tc=10.0 min CN=98 Runoff=2.55 cfs 0.327 af
Subcatchment19S: Study Area WQ MTD Runoff Area=0.020 ac 0.00% Impervious Runoff Depth=0.66" Flow Length=351' Tc=10.0 min CN=39 Runoff=0.00 cfs 0.001 af
Pond 17P: Basin A Routing (StormBrixx) Peak Elev=120.31' Storage=8,183 cf Inflow=3.02 cfs 0.388 af Outflow=1.06 cfs 0.300 af
Link 18L: Study Area Study Area WQ MTD A-110 (Total) Inflow=2.56 cfs 0.329 af Primary=2.56 cfs 0.329 af
Link 19L: Study Area Basin A (Total) Inflow=3.02 cfs 0.388 af Primary=3.02 cfs 0.388 af
Total Runoff Area = 0.740 ac Runoff Volume = 0.388 af Average Runoff Depth = 6.28
Total Runoff Area = 0.740 ac Runoff Volume = 0.388 af Average Runoff Depth = 6.28"
2.70% Pervious = 0.020 ac 97.30% Impervious = 0.720 ac
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2026-02 Offsite Stability NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 16S: Study Area Roof (Imp)
Runoff = 0.46 cfs @ 12.19 hrs, Volume= 0.059 af, Depth= 6.44"
Routed to Link 191 : Study Area Basin A (Total)
Routed to Link 19L : Study Area Basin A (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Area (ac) CN Description
0.110 98 Roofs, HSG A
0.110 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs)
0.8 207 0.0100 4.50 1.57 Pipe Channel, A-B 8.0" Round Area= 0.3 sf Perim= 2.1' r= 0.17' n= 0.010 PVC, smooth interior
0.8 207 Total, Increased to minimum Tc = 10.0 min
Subcatchment 16S: Study Area Roof (Imp)
| 2026-02 Offsite Stability | NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC | Page 10 |
Summary for Subcatchment 18S: Study Area WQ MTD A-110 (Imp)
Runoff = 2.55 cfs @ 12.19 hrs, Volume= 0.327 af, Depth= 6.44"
Routed to Link 18L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Area (ac) CN Description
0.610 98 Paved parking, HSG A
0.610 98 100.00% Impervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
0.6 55 0.0302 1.62 Sheet Flow, A-B Smooth surfaces n= 0.011 P2= 4.04"
1.3 297 0.0035 3.68 4.52 Pipe Channel, B-C 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
1.9 352 Total, Increased to minimum Tc = 10.0 min
Subcatchment 18S: Study Area WQ MTD A-110 (Imp)
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2026-02 Offsite Stability NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 19S: Study Area WQ MTD A-110 (Perv)
Runoff = 0.00 cfs @ 12.38 hrs, Volume= 0.001 af, Depth= 0.66"
Routed to Link 18L : Study Area Study Area WQ MTD A-110 (Total)
Runoff by SCS TR-20 method, UH=Delmarva, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Area (ac) CN Description
0.020 39 >75% Grass cover, Good, HSG A
0.020 39 100.00% Pervious Area
Tc (min) Length (feet) Slope (ft/ft) Velocity (ft/sec) Capacity (cfs) Description
1.4 8 0.0125 0.10 Sheet Flow, A-B Grass: Short n= 0.150 P2= 4.04"
0.2 46 0.0380 3.96 Shallow Concentrated Flow, B-C Paved Kv= 20.3 fps
1.3 297 0.0035 3.68 4.52 Pipe Channel, C-D 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.011 Concrete pipe, straight & clean
2.9 351 Total, Increased to minimum Tc = 10.0 min
Subcatchment 19S: Study Area WQ MTD A-110 (Perv)
| 2026-02 Offsite Stability | NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04" |
|---|---|
| Prepared by Dynamic Engineering | Printed 2/10/2026 |
| HydroCAD ® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC | Page 12 |
Summary for Pond 17P: Basin A Routing (StormBrixx)
| Inflow Area = | 0.740 ac, 97.30% Impervious, Inflow Depth = 6.28" for 25-Year event |
|---|---|
| Inflow = | 3.02 cfs @ 12.19 hrs, Volume= 0.388 af |
| Outflow = | 1.06 cfs @ 12.67 hrs, Volume= 0.300 af, Atten= 65%, Lag= 29.0 min |
| Primary = | 1.06 cfs @ 12.67 hrs, Volume= 0.300 af |
| Routed to nonexistent node 14L | |
Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs
Peak Elev= 120.31' @ 12.67 hrs Surf.Area= 3,001 sf Storage= 8,183 cf
Plug-Flow detention time=244.3 min calculated for 0.300 af (77% of inflow) Center-of-Mass det. time=155.0 min (910.0 - 755.0)
| Volume | Invert | Avail.Storage | Storage Description |
|---|---|---|---|
| #1A | 117.50' | 0 cf | 31.63'W × 94.88'L × 3.00'H Field A |
| #2A | 117.50' | 8,729 cf | 8,999 cf Overall - 8,999 cf Embedded = 0 cf × 40.0% Voids\nACO StormBrixx SD 1 × 384 Inside #1\nInside= 23.7"W × 36.0"H => 5.75 sf × 3.95'L = 22.7 cf\nOutside= 23.7"W × 36.0"H => 5.93 sf × 3.95'L = 23.4 cf\n384 Chambers in 16 Rows |
8,729 cf Total Available Storage
Storage Group A created with Chamber Wizard
| Device | Routing | Invert | Outlet Devices |
|---|---|---|---|
| #1 | Primary | 117.50' | 15.0" Round Culvert L= 22.0' RCP, groove end projecting, Ke= 0.200 Inlet / Outlet Invert= 117.50' / 117.40' S= 0.0045'' Cc= 0.900 n= 0.013, Flow Area= 1.23 sf |
| #2 | Device 1 | 118.81' | 6.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads |
Primary OutFlow Max=1.06 cfs @ 12.67 hrs HW=120.31' (Free Discharge)
1=Culvert (Passes 1.06 cfs of 9.70 cfs potential flow)
2=Orifice (Orifice Controls 1.06 cfs @ 5.38 fps)
Page 128
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2026-02 Offsite Stability NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 13
Pond 17P: Basin A Routing (StormBrixx) - Chamber Wizard Field A
Chamber Model = ACO StormBrixx SD 1 (ACO StormBrixx® SD)
Inside = 23.7" W x 36.0" H => 5.75 sf x 3.95' L = 22.7 cf
Outside = 23.7" W x 36.0" H => 5.93 sf x 3.95' L = 23.4 cf
24 Chambers/Row x 3.95' Long = 94.88' Row Length
16 Rows x 23.7" Wide = 31.63' Base Width
36.0" Chamber Height = 3.00' Field Height
384 Chambers x 22.7 cf = 8.728.7 cf Chamber Storage
384 Chambers x 23.4 cf = 8.998.6 cf Displacement
Chamber Storage = 8,728.7 cf = 0.200 af
Overall Storage Efficiency = 97.0%
Overall System Size = 94.88' x 31.63' x 3.00'
384 Chambers
333.3 cy Field
2026-02 Offsite Stability NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 14
Pond 17P: Basin A Routing (StormBrixx)
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2026-02 Offsite Stability NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 15
Summary for Link 18L: Study Area Study Area WQ MTD A-110 (Total)
Inflow Area = 0.630 ac, 96.83% Impervious, Inflow Depth = 6.26" for 25-Year event
Inflow = 2.56 cfs @ 12.19 hrs, Volume = 0.329 af
Primary = 2.56 cfs @ 12.19 hrs, Volume = 0.329 af, Atten = 0%, Lag = 0.0 min
Routed to Link 191: Study Area Basin A (Total)
Routed to Link 19L : Study Area Basin A (Total)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Fixed water surface Elevation= 117.75'
Link 18L: Study Area Study Area WQ MTD A-110 (Total)
2026-02 Offsite Stability NOAA 24-hr D 25-Year Rainfall=6.68", P2=4.04"
Prepared by Dynamic Engineering Printed 2/10/2026
HydroCAD® 10.20-8a s/n 08640 © 2025 HydroCAD Software Solutions LLC Page 16
Summary for Link 19L: Study Area Basin A (Total)
Inflow Area = 0.740 ac, 97.30% Impervious, Inflow Depth = 6.28" for 25-Year event
Inflow = 3.02 cfs @ 12.19 hrs, Volume= 0.388 af
Primary = 3.02 cfs @ 12.19 hrs, Volume= 0.388 af, Atten= 0%, Lag= 0.0 min
Routed to Pond 17P : Basin A Routing (StormBrixx)
Primary outflow = Inflow, Time Span = 0.00-72.00 hrs, dt = 0.05 hrs
Link 19L: Study Area Basin A (Total)
Hydrograph
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STORMWATER BASIN AREA INVESTIGATION REPORT, PREPARED BY DYNAMIC EARTH, LLC
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DRAINAGE AREA MAPS
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Plotted: 02/13/26 – 10:31 AM, By: cmancilla
File: P:\DECPC PROJECTS\3342 Sterling Education Group LLC\99-007 Jackson\Dwg\DA Maps\D334299007EDAM3.dwg, ----> 01 EXISTING DRAINAGE AREA MAP
THIS PLAN SET IS FOR PERMITTING PURPOSES ONLY AND MAY NOT BE USED FOR CONSTRUCTION
DRAWN BY: DESIGNED BY: CHECKED BY: CHECKED BY:
MFD MJP RTO -
PROJECT: 3 PROPOSED OFFICE BUILDING BLOCK 20901, LOT 15 30 SOUTH HOPE CHAPEL ROAD (C.R. 547) TOWNSHIP OF JACKSON, OCEAN COUNTY, NEW JERSEY 3 02/12/26 REV. PER TOWNSHIP, COUNTY & SCD COMMENTS CAM
2 07/10/25 REV. PER PINELANDS COMMENTS RPK
1 04/18/25 REV. PER PINELANDS COMMENTS YL
REV. DATE COMMENTS BY
811
PROTECT YOURSELF
ALL STATES REQUIRE NOTIFICATION OF EXCAVATORS, DESIGNERS, OR ANY PERSON PREPARING TO DISTURB THE EARTH'S SURFACE ANYWHERE IN ANY STATE
OR STATE SPECIFIC DIRECT PHONE NUMBERS VISWWW.CALL811.COM
DYNAMIC ENGINEERING
PERMITTING
ENVIRONMENTAL
TRAFFIC • SURVEY • PLANNING & ZONING
5 Greentree Centre, Suite 406
Marlton, NJ 08053
T: 856.334.2000 | F: 732.974.3521
Offices conveniently located at:
Lake Como, New Jersey • T: 732.974.0198
Chester, New Jersey • T: 908.879.9229
Marlton, New Jersey • T: 856.334.2000
Newark, New Jersey • T: 973.755.7200
Toms River, New Jersey • T: 732.687.0000
Newtown, Pennsylvania • T: 267.685.0276
Philadelphia, Pennsylvania • T: 215.253.4888
Bethlehem, Pennsylvania • T: 610.598.4400
Allen, Texas • T: 972.534.2100
Houston, Texas • T: 281.789.6400
Austin, Texas • T: 512.646.2646
Delray Beach, Florida • T: 561.921.8570
www.dynamicec.com
RICHARD T. ORTIZ
PROFESSIONAL ENGINEER
NEW JERSEY LICENSE No. 60149
RODMAN R. RITCHIE
PROFESSIONAL ENGINEER NEW JERSEY LICENSE No. 43547
EXISTING DRAINAGE AREA MAP
SCALE: (H) 1"=20'
(V) DATE/(08/11/2)
PROJECT No: 3342-99-007
1
OF 2 | Rev. #: 3
(IN FEET)
INCH = 20 FT.
OF 2 3
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Plotted: 02/13/26 – 10:31 AM, By: cmancilla
File: P:\DECPC PROJECTS\3342 Sterling Education Group LLC\99-007 Jackson\Dwg\DA Maps\D334299007PDAM3.dwg, ----> 02 PROPOSED DRAINAGE AREA MAP
(IN FEET)
INCH = 20 FT.
Page 134
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Plotted: 02/13/26 – 10:31 AM, By: cmancilla
File: P:\DECPC PROJECTS\3342 Sterling Education Group LLC\99-007 Jackson\Dwg\DA Maps\D334299007PIAM3.dwg, ----> 03 INLET AREA MAP
THIS PLAN TO BE UTILIZED FOR LIGHTING PURPOSES ONLY
(IN FEET)
INCH = 20 FT.
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NITROGEN REMOVAL EXHIBIT
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Plotted: 02/13/26 – 10:28 AM, By: cmancilla
File: P:\DECPC PROJECTS\3342 Sterling Education Group LLC\99-007 Jackson\Dwg\Exhibits (Misc)\Nitrogen Exhibit\D334299007Nitrogen3.dwg, ----> NITROGEN EXHIBIT
(IN FEET)
INCH = 20 FT.
| THIS PLAN SET IS FOR PERMITTING PURPOSES | ONLY AND MAY NOT BE USED FOR CONSTRUCTION | CHECKED BY: | RTO | MJP | PROJECT: | 1980 SWARTHMORE LLC | PROPOSED OFFICE BUILDING | BLOCK 20901, LOT 15 | 30 SOUTH HOPE CHAPEL ROAD (C.R. 547) | TOWNSHIP OF JACKSON, OCEAN COUNTY, NEW JERSEY |
|---|---|---|---|---|---|---|---|---|---|---|
| DESIGNED BY: | YL | YL | YL | PROJECT: | 1980 SWARTHMORE LLC | PROPOSED OFFICE BUILDING | BLOCK 20901, LOT 15 | TOWNSHIP OF JACKSON, OCEAN COUNTY, NEW JERSEY | ||
| DRAWN BY: | 811 | 811 | 811 | PROJECT: | 1980 SWARTHMORE LLC | PROPOSED OFFICE BUILDING | PROPOSED OFFICE BUILDING | TOWNSHIP OF JACKSON, OCEAN COUNTY, NEW JERSEY | ||
| Knewh's below Call before you dg. | 811 | 811 | 811 | 811 | PROJECT: | 1980 SWARTHMORE LLC | PROPOSED OFFICE BUILDING | PROPOSED OFFICE BUILDING | ||
| FOR STATE SPECIFIC DIRECT PHONE NUMBERS VISIT: WWW.CALL811.COM | ||||||||||
| DYNAMIC ENGINEERING | ||||||||||
| LAND DEVELOPMENT CONSULTING • PERMITTING GEOTECHNICAL • ENVIRONMENTAL TRAFFIC • SURVEY • PLANNING & ZONING | ||||||||||
| 5 Greentree Centre, Suite 406 | ||||||||||
| Marlton, NJ 08053 | ||||||||||
| T: 856.334.2000 | F: 732.974.3521 | ||||||||||
| Offices conveniently located at: | ||||||||||
| Loke Corrio, New Jersey • T: 722.974.0178 | ||||||||||
| Charlott, New Jersey • T: 908.879.9229 | ||||||||||
| Newark, New Jersey • T: 856.334.2000 | ||||||||||
| Tom's River, New Jersey • T: 973.755.7200 | ||||||||||
| Newtown, Pennsylvania • T: 732.687.0000 | ||||||||||
| Philadelphia, Pennsylvania • T: 267.685.00276 | ||||||||||
| Bethlehem, Pennsylvania • T: 610.598.4400 | ||||||||||
| Allen, Texas • T: 972.534.2100 | ||||||||||
| Houshou, Texas • T: 281.109.6440 | ||||||||||
| Austin, Texas • T: 512.646.2646 | ||||||||||
| Delray Beach, Florida • T: 561.921.8570 | ||||||||||
| www.dynamic.ice.com | ||||||||||
| RICHARD T. ORTIZ | ||||||||||
| PROFESSIONAL ENGINEER | ||||||||||
| NEW JERSEY LICENSE No. 60149 | ||||||||||
| RODMAN R. RITCHIE | ||||||||||
| PROFESSIONAL ENGINEER | ||||||||||
| NEW JERSEY LICENSE No. 43547 | ||||||||||
| TITLE: | ||||||||||
| NITROGEN | ||||||||||
| EXHIBIT | ||||||||||
| SCALE: (H) 1"=20" (V) | DATE: | |||||||||
| PROJECT No: | 10/11/2024 | |||||||||
| 3342-99-007 | ||||||||||
| SHEET No: | Rev. #: | |||||||||
OF 1 3