Public Works Department - Stormwater Management

Watershed Reports
Milldam Creek

Entire study pdf (90 pages - 284 MB) - print quality

Entire study pdf (90 pages - 142 MB) - viewing quality

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Table of Contents

1. Executive Summary
2. Introduction
3. Watershed Issues & Background
   
   
4. Computer Modeling     (entire Section #4- 16 pages - 141.4 MB)

   4.1 Data Sources & Processing

   4.2 Methodology

   4.3 Model Development & Selection of Parameters

   4.3.1  SWMM RUNOFF & EXTRAN Blocks
   4.3.2  SWMM Engine, Numerical Solutions, Time Steps
   4.3.3  Rainfall Hyetographs
   4.3.4  Subarea Delineation
   4.3.5  Subcatchment Width
   4.3.6  Subcatchment Slope
   4.3.7  Subcatchment Imperviousness, Roughness & Depression Storage
   4.3.8  Subcatchment Basins
   4.3.9  Green-Ampt Soils Parameters
   4.3.10  Drainage Network Discretization (Links and Nodes)
   4.3.11  Missing Pipe & Channel Data
   4.3.12  Treatment of EXTRAN Flooding
   4.3.13  Channel Roughness
   4.3.14  Outfall Boundary Conditions

   4.3.15  Important Considerations and Implications Regarding Boundary Conditions and Return Periods

   
   

   4.4 Figure 4.4 -

   4.5 Figure 4.5 -

   4.6 Figure 4.6 -

5. Modeling Scenarios & Computer Files 
   

   5.1 Vertical Datum

   5.2 Existing (2003) Conditions Models

   5.3 Future Conditions Models

6. Modeling Results
   

   6.1 Existing (2003) Conditions Maximum Water Surface Elevations

   6.2 Future Conditions Maximum Water Surface Elevations

7. Master Drainage Plan Improvements
   

   7.1 New 32-Foot Bridge at Campostella Road

   7.2 Widen Channel to 40 Feet Between Campostella Road and Military Highway

   7.3 New 6x6 Box Culvert at Military Highway

   7.4 New Stormwater Management Basins East of Battlefield Boulevard

Appendix A.  Subcatchment Imperviousness & Soil Parameters

Appendix B.  Pro-Rata Share Program Evaluation

B.1  Introduction
B.2  Pro Rata Share Calculations Options

B.2.1  Pro Rata Share Calculations Based on a Billing Unit
B.2.2  Pro Rata Share Calculations Based on Actual Measurement of All Parcels
B.2.3  Pro Rata Share Calculations Using Rational Coefficients
B.2.4  Pro Rata Share Based on a Flat Rate
B.2.5  Summary of Calculation Methods

B.3  Credits
B.4  Recommended Improvements inthe Milldam Creek Watershed

For more information, please contact:

Sam Sawan
P.E. Senior Stormwater Engineer
Chesapeake Public Works Department
Engineering

Phone: 757-382-6101
FAX: 757-382-8537

Email