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Maryland ESD Spreadsheet

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					Maryland ESD Calculations - Draft 2/10/10


Project Name:
Date:

                                                data input cells
                                                calculation cells



Step 1: Complete ESD Implementation Checklist

Check all of the Following ESD Practices That Were Implemented at Site                        Yes - No - N/A
Environmental Mapping Was Conducted at Site Prior to Layout
Natural Areas Were Conserved (e.g., forests, wetlands, steep slopes, floodplains)
Stream, Wetland and Shoreline Buffers Were Reserved
Disturbance of Permeable Soils Was Minimized
Natural Flow Paths Were Maintained Across the Site
Building Layout Was Fingerprinted to Reduce Clearing and Grading at Site
Site Grading Promoted Sheetflow From Impervious Areas to Pervious Ones
Site Design Was Evaluated to Reduce Creation of Needless Impervious Cover
Site Design Was Evaluated to Maximize Disconnection of Impervious Cover
Site Design Was Evaluated to Identify Potential Hotspot Generating Area for Stormwater
Treatment
Erosion and Sediment Control Practices and Post Construction Stormwater Management
Practices Were Integrated into a Comprehensive Plan
Tree PlantingWas Used at the Site to Convert Turf Areas into Forest

Step 2: Calculate Site Imperviousness and Water Quality Volume, WQv                                             Step 3: Calculate Phosphorous Removal Requirement, RR for Critical Area Sites

Site Area, A (acres)                                                                                            New Development
Existing Impervious Surface Area (acres)                                                                        Average Annual Predevelopment Load, Lpre (lbs P / yr)                            0.00
Proposed Impervious Surface Area (acres)
                                                                                                                Redevelopment:
Existing Imperviousness, Ipre                          #DIV/0!                                                  Predevelopment Runoff Coefficient, Rvpre                                       #DIV/0!
Proposed Imperviousness, Ipost                         #DIV/0!                                                  Phosphorous Mean Concentration, C (mg/L)                                         0.3
                                                                                                                Average Annual Predevelopment Load, Lpre (lbs P / yr)                          #DIV/0!
Development Category                                   #DIV/0!
                                                                                                                Post-Development Runoff Coefficient, Rvpost                                    #DIV/0!
                                                                                                                Average Annual Post-Development Load, Lpost (lbs P / yr)                       #DIV/0!
Rainfall Depth, P (in)
Runoff Coefficient, Rv                                 #DIV/0!                                                  Removal Requirement, RR (lbs P / yr)                                           #DIV/0!
Water Quality Volume, WQv (ac-in)                      #DIV/0!
Water Quality Volume, WQv (cf)                         #DIV/0!

Step 4: Calculate Environmental Site Design (ESD) Rainfall Target, PE

% Soil Type A                                            0%
% Soil Type B                                            0%
% Soil Type C                                            0%
% Soil Type D                                            0%

Pre-Developed Condition, RCN woods                        0

New Development                                                                            Redevelopment
Soil Type A ESD Rainfall Target, PE (in)               #DIV/0!                             Soil Type A ESD Rainfall Target, PE (in)       #DIV/0!
Soil Type B ESD Rainfall Target, PE (in)               #DIV/0!                             Soil Type B ESD Rainfall Target, PE (in)       #DIV/0!
Soil Type C ESD Rainfall Target, PE (in)               #DIV/0!                             Soil Type C ESD Rainfall Target, PE (in)       #DIV/0!
Soil Type D ESD Rainfall Target, PE (in)               #DIV/0!                             Soil Type D ESD Rainfall Target, PE (in)       #DIV/0!

Site ESD Rainfall Target, P E (in)                     #DIV/0!

ESD Runoff Depth, QE (in)                              #DIV/0!
ESD Runoff Volume, ESDv (cf)                           #DIV/0!


Required Recharge Volume, Rev (ac-ft)                  #DIV/0!
Required Recharge Volume, Rev (cf)                     #DIV/0!

Step 5: Select Alternative Surfaces to Reduce Target PE and Phosphorous Removal Requirement
                                                Contributing                                                                          Critical Area Credits
Alternative Surfaces                            Drainage Area (ac)   Thickness             Effective RCN                              Credit           Credit Area
Green Roof (on Soil Type A)                                                                          0
Green Roof (on Soil Type B)                                                                          0                                 50% of S.A.            0.00
Green Roof (on Soil Type C)                                                                          0                                removed from
Green Roof (on Soil Type D)                                                                          0                                IC calculation
Permeable Pavement (Soil Type A)                                                                     0                                 50% of S.A.
Permeable Pavement (Soil Type B)                                                                     0                                removed from            0.00
Permeable Pavement (Soil Type C)                                                                     0                                IC calculation

New Development                                                                            Redevelopment
Modified CN for Soil Type A, RCN*                         0                                Modified CN for Soil Type A, RCN*                 0
Modified CN for Soil Type B, RCN*                         0                                Modified CN for Soil Type B, RCN*                 0
Modified CN for Soil Type C, RCN*                         0                                Modified CN for Soil Type C, RCN*                 0
Modified CN for Soil Type D, RCN*                         0                                Modified CN for Soil Type D, RCN*                 0

Soil Type A ESD Rainfall Target, PE (in)                0.00                               Soil Type A ESD Rainfall Target, PE (in)        0.00
Soil Type B ESD Rainfall Target, PE (in)                0.00                               Soil Type B ESD Rainfall Target, PE (in)        0.00
Soil Type C ESD Rainfall Target, PE (in)                0.00                               Soil Type C ESD Rainfall Target, PE (in)        0.00
Soil Type D ESD Rainfall Target, PE (in)                0.00                               Soil Type D ESD Rainfall Target, PE (in)        0.00

Reduced Site ESD Rainfall Target, P E (in)             #DIV/0!                                                  Critical Area Sites
                                                                                                                Post-Development Runoff Coefficient, Rvpost                    #DIV/0!
ESD Runoff Depth, QE (in)                              #DIV/0!                                                  Average Annual Post-Development Load, Lpost (lbs P / yr)       #DIV/0!
ESD Runoff Volume, ESDv (cf)                           #DIV/0!
                                                                                                                Reduced Removal Requirement, RR (lbs P / yr)                   #DIV/0!

Step 6: Select Nonstructural Practices to Treat the ESD Rainfall Target
                                                                                                                                                                                                                                                                                                        Critical Area Credits



                                                                                                                                                                                                                            Runoff
                                                                                              Contributing          Direct ESDv        ESDv from                                                                            Volume       Enhanced
                                                                                            Impervious Cover        Received by        Upstream                                                                ESDv        Remaining   Filter Volume                                                    Phosphorous             Load Reduction
Nonstructural Practices                                    PE Credit Description                  (ac)              Practice (cf)     Practices (cf)     Practice Specific Parameter(s)     PE Credit (in)   credit (cf)      (cf)           (cf)      Rev (cf)                                         Removal Efficiency      (lbs/yr)
                                                 Up to 1 inch credit provided based upon                                                                  Flow Path (ft)      East/West
Disconnection of Rooftop Runoff (A/B Soils)             disconnection flow length.                                     #DIV/0!               0                                                    0           #DIV/0!       #DIV/0!                    #DIV/0!                                                  50%                 #DIV/0!
                                                 Up to 1 inch credit provided based upon
Disconnection of Rooftop Runoff (C/D Soils)             disconnection flow length.                                     #DIV/0!               0                                                    0           #DIV/0!       #DIV/0!                    #DIV/0!                                                  25%                 #DIV/0!
                                                                                                                                                                            Contributing
                                                Up to 1 inch credit provided based upon                                                                  Disconnection        Length (ft)
                                                  disconnection and contributing flow                                                                      Length (ft)      (Impervious)
Disconnection of Non-Rooftop Runoff (A/B Soils)                 lengths.                                               #DIV/0!               0                                                    0           #DIV/0!       #DIV/0!                    #DIV/0!                                                  50%                 #DIV/0!
Disconnection of Non-Rooftop Runoff (C/D        Up to 1 inch credit provided based upon
Soils)                                            disconnection and contributing flow                                  #DIV/0!               0                                                    0           #DIV/0!       #DIV/0!                    #DIV/0!                                                  25%                 #DIV/0!
                                                Up to 1 inch credit provided based upon                                                                Minimum Width (ft)
Sheetflow to Conservation Areas (A/B Soils)             conservation area width.                                       #DIV/0!               0                                                    0           #DIV/0!       #DIV/0!                    #DIV/0!                                                  50%                 #DIV/0!
                                                Up to 1 inch credit provided based upon
Sheetflow to Conservation Areas (C/D Soils)             conservation area width.                                       #DIV/0!               0                                                    0           #DIV/0!       #DIV/0!                    #DIV/0!                                                  25%                 #DIV/0!

Step 7: Select Micro-Scale Practices to Treat the ESD Rainfall Target
                                                                                                                                                                                                                            Runoff
                                                                                              Contributing          Direct ESDv        ESDv from                                                                            Volume       Enhanced
                                                                                            Impervious Cover        Received by        Upstream                                                                ESDv        Remaining   Filter Volume                                                    Phosphorous             Load Reduction
Micro-Scale Practices                                      PE Credit Description                  (ac)              Practice (cf)     Practices (cf)     Practice Specific Parameter(s)          PE          credit (cf)      (cf)           (cf)      Rev (cf)          Downstream Practice            Removal Efficiency      (lbs/yr)

                                                                                                                                                       Design Volume (cf)
Rainwater Harvesting                               PE credit is based on design volume                                 #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  45%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)    Depth* (ft)
Submerged Gravel Wetlands                          PE credit is based on design volume                                 #DIV/0!               0                                  2.2            #DIV/0!        #DIV/0!       #DIV/0!                       0                                                     60%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)    Depth* (ft)
Micro-Infiltration                                 PE credit is based on design volume                                 #DIV/0!               0                                  1.6            #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  65%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)
Rain Gardens (A/B Soils)                         PE = 10" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  50%                 #DIV/0!

Rain Gardens (C/D Soils)                         PE = 10" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  25%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)
Bioretention (A/B Soils)                         PE = 15" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  75%                 #DIV/0!
                                                                                                                                                                                                                                                                  Stormwater Filtering Systems (Level
Bioretention (C/D Soils)                         PE = 15" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                     2)                           50%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)
Landscape Infiltration                           PE = 20" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  75%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)
Grass Swales (A/B Soils)                         PE = 10" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  40%                 #DIV/0!

Grass Swales (C/D Soils)                         PE = 10" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                       0                                                     20%                 #DIV/0!

                                                                                                                                                        Surface Area (sf)
Bio-swales (A/B Soils)                           PE = 15" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  75%                 #DIV/0!

Bio-swales (C/D Soils)                           PE = 15" x Surface Area / Drainage Area                               #DIV/0!               0                                                 #DIV/0!        #DIV/0!       #DIV/0!                    #DIV/0!                                                  50%                 #DIV/0!
Bio-swales (C/D Soils)                   PE = 15" x Surface Area / Drainage Area                             #DIV/0!              0                                               #DIV/0!       #DIV/0!     #DIV/0!                    #DIV/0!                                     50%            #DIV/0!

                                                                                                                                             Surface Area (sf)   Depth* (ft)
Wet Swales                                PE credit is based on design volume                                #DIV/0!              0                                 1.0           #DIV/0!       #DIV/0!     #DIV/0!                    #DIV/0!                                     40%            #DIV/0!

Step 8: Check Site Compliance for WQv, ESDv, Rev, and Load Reduction and Revise Site If Necessary

                                                  Impervious Cover Treated (ac)                     0                                                                     ESDv Treated (cf)     #DIV/0!               Total Rev (cf)   #DIV/0!              Total Load Reduction (lbs P / year)   #DIV/0!
                                                                                                                                                                        PE achieved (inches)    #DIV/0!                                          Total Load Reduction Remaining (lbs P / yr)      #DIV/0!



                                                                                                                            WQv Requirements Met Through Environmental Site Design?             #DIV/0!
                                                                                                                                                                 WQv Remaining? (cf)            #DIV/0!
                                                                                                                               Entire ESDv Treated Through Environmental Site Design?           #DIV/0!
                                                                                                                                                                 ESDv Remaining? (cf)           #DIV/0!
                                                                                                                             Rev Requirements Met Through Environmental Site Design?            #DIV/0!
                                                                                                                                                                   Rev Remaining? (cf)          #DIV/0!


Step 9: Determine Reduced RCN and Required Channel Protection Volume (CPv) Based Upon PE Achieved

Reduced RCN for Type A Soils                  #DIV/0!
Reduced RCN for Type B Soils                  #DIV/0!
Reduced RCN for Type C Soils                  #DIV/0!
Reduced RCN for Type D Soils                  #DIV/0!

Composite Reduced RCN                         #DIV/0!

Q (in)                                        #DIV/0!
CPv Treatment Required (cf)                   #DIV/0!

Step 10: Select Structural Practices to Meet the CPv
                                                                                                                                                                               Critical Area Credits
                                           Contributing         Direct ESDv            ESDv from                              Enhanced                                         Phosphorous         Load
                                         Impervious Cover       Received by        Upstream Practices    Treatment Volume   Filter Volume                                         Removal       Reduction
Structural Practices                           (ac)             Practice (cf)             (cf)                 (cf)               (cf)           Rev (cf)                        Efficiency      (lbs/yr)
Stormwater Ponds (Level 1)                                         #DIV/0!                  0                                                      0                                 50%         #DIV/0!
Stormwater Ponds (Level 2)                                         #DIV/0!                  0                                                      0                                 75%         #DIV/0!
Stormwater Wetlands (Level 1)                                      #DIV/0!                  0                                                                                        50%         #DIV/0!
Stormwater Wetlands (Level 2)                                      #DIV/0!                  0                                                                                        75%         #DIV/0!
Stormwater Filtering Systems (Level 1)                             #DIV/0!                  0                                                        0                               60%         #DIV/0!
Stormwater Filtering Systems (Level 2)                             #DIV/0!               #DIV/0!                                                     0                               65%         #DIV/0!
Stormwater Infiltration (Level 1)                                  #DIV/0!                  0                                                                                        60%         #DIV/0!
Stormwater Infiltration (Level 2)                                  #DIV/0!                  0                                                                                        90%         #DIV/0!

                                                                         Total structural CPv provided          0                                        Total Load Reduction (lbs P / year)    #DIV/0!
                                                                             CPv Requirement Met?            #DIV/0!                          Total Load Reduction Remaining (lbs P / yr)       #DIV/0!
                                                                                      CPv Remaining          #DIV/0!

                                                                                                                   Total Rev provided (cf)       #DIV/0!
                                                                                                                  Rev Requirement Met?           #DIV/0!
                                                                                                                    Rev Remaining? (cf)          #DIV/0!
                   Target PE Tables
                                  Hydrologic Soil Group A                                                        Hydrologic Soil Group B                      Hydrologic Soil Group C                Hydrologic Soil Group D                                             Hydrologic Soil Group A                                                #DIV/0!   This number determines the row to use in the Soil Group tables (based upon impervious percentage) when calculating a reduced RCN.
                         %I              RCN*                  PE                                   %I                   RCN*              PE           %I           RCN*               PE     %I    RCN*                      PE          %I          RCN*   1    1.2        1.4                  1.6   1.8   2    2.2   2.4   2.6         1
                        0%                40                    1                                  0%                     61                1          0%              74                1    0%       80                       1         0%            40    38   38         38                   38    38    38   38    38    38         2                                          0%           2
                        1%                40.5                  1                                  1%                    61.5               1          1%             74.5               1    1%      80.5                      1         5%            43    38   38         38                   38    38    38   38    38    38         3                                          1%           3
                        5%                43                    1                                  5%                     63                1          5%              75                1    5%       81                       1         10%           46    38   38         38                   38    38    38   38    38    38         4                                          5%           3
                        6%                43.5                  1                                  6%                    63.5               1          6%             75.5               1    6%      81.5                      1         15%           48    38   38         38                   38    38    38   38    38    38         5                                          6%           4
                        10%               46                    1                                  10%                    65                1          10%             76                 1   10%      82                       1         20%           51    40   38         38                   38    38    38   38    38    38          6                                        10%           4
                        11%               46.5                  1                                  11%                   65.5               1          11%            76.5                1   11%     82.5                      1         25%           54    41   40         39                   38    38    38   38    38    38          7                                        11%           5
                        15%                48                   1                                  15%                    67                1          15%             78                 1   15%      83                       1         30%           57    42   41         39                   38    38    38   38    38    38          8                                        15%           5
                        16%               48.5                 1.2                                 16%                   67.5              1.2         16%            78.5                1   16%     83.5                      1         35%           60    44   42         40                   39    38    38   38    38    38          9                                        16%           6
                        20%                51                  1.2                                 20%                    68               1.2         20%             79                1    20%      84                       1         40%           61    44   42         40                   39    38    38   38    38    38         10                                        20%           6
                        21%               51.5                 1.6                                 21%                   68.5              1.6         21%            79.5              1.2   21%     84.5                     1.2        45%           66    48   46         41                   40    38    38   38    38    38         11                                        21%           7
                        25%                54                  1.6                                 25%                    70               1.6         25%             80               1.2   25%      85                      1.2        50%           69    51   48         42                   41    38    38   38    38    38         12                                        25%           7
                        26%               54.5                 1.6                                 26%                   70.5              1.6         26%            80.5              1.6   26%     85.5                     1.2        55%           72    54   50         42                   41    39    38   38    38    38         13                                        26%           8
                        30%                57                  1.6                                 30%                    72               1.6         30%             81               1.6   30%      85                      1.2        60%           74    57   52         44                   42    40    38   38    38    38         14                                        30%           8
                        31%               57.5                 1.8                                 31%                   72.5              1.8         31%            81.5              1.6   31%     85.5                     1.6        65%           77    61   55         47                   44    42    40   38    38    38         15                                        31%           9
                        35%                60                  1.8                                 35%                    74               1.8         35%             82               1.6   35%      86                      1.6        70%           80    66   61         55                   50    45    40   38    38    38
                                                                                                                                                                                                                                                                                                                                           16                                        35%           9
                        36%               60.5                 1.8                                 36%                   74.5              1.8         36%            82.5              1.8   36%     86.5                     1.6        75%           84    71   67         62                   56    48    40   38    38    38         17                                        36%          10
                        40%                61                  1.8                                 40%                    75               1.8         40%             84               1.8   40%      87                      1.6        80%           86    73   70         65                   60    52    44   40    38    38         18                                        40%          10
                        41%               61.5                 1.8                                 41%                   75.5              1.8         41%            84.5              1.8   41%     87.5                     1.8        85%           89    77   74         70                   65    58    49   42    38    38         19                                        41%          11
                        45%                66                  1.8                                 45%                    78               1.8         45%             85               1.8   45%      88                      1.8        90%           92    81   78         74                   70    65    58   48    42    38
                                                                                                                                                                                                                                                                                                                                           20                                        45%          11
                        46%               66.5                 1.8                                 46%                   78.5              1.8         46%            85.5              1.8   46%     88.5                     1.8        95%           95    85   82         78                   75    70    65   57    50    39         21                                        46%          12
                        50%                69                  1.8                                 50%                    80               1.8         50%             86               1.8   50%      89                      1.8       100%           98    89   86         83                   80    76    72   66    59    40         22                                        50%          12
                        51%               69.5                  2                                  51%                   80.5              1.8         51%            86.5              1.8   51%     89.5                     1.8                                                                                                                                                   51%          13
                        55%                72                   2                                  55%                    81               1.8         55%             86               1.8   55%      90                      1.8                                                                                                                                                   55%          13
                        56%               72.5                  2                                  56%                   81.5               2          56%            86.5               2    56%     90.5                     1.8                                       Hydrologic Soil Group B                                                                                     56%          14
                        60%                74                   2                                  60%                    83                2          60%             88                2    60%      91                      1.8         %I          RCN*    1   1.2        1.4                1.6     1.8    2   2.2   2.4   2.6                                                  60%          14
                        61%               75.5                 2.2                                 61%                   83.5               2          61%            88.5               2    61%     91.5                     1.8        0%            61    55   55         55                 55      55    55   55    55    55                                                   61%          15
                        65%                77                  2.2                                 65%                    85                2          65%             90                2    65%      92                      1.8        5%            63    55   55         55                 55      55    55   55    55    55                                                   65%          15
                        66%               77.5                 2.2                                 66%                   85.5              2.2         66%            90.5               2    66%     92.5                     1.8        10%           65    55   55         55                 55      55    55   55    55    55                                                   66%          16
                        70%                80                  2.2                                 70%                    87               2.2         70%             91                2    70%      93                      1.8        15%           67    55   55         55                 55      55    55   55    55    55                                                   70%          16
                        71%               80.5                 2.2                                 71%                   87.5              2.2         71%            91.5               2    71%     93.5                     1.8        20%           68    60   55         55                 55      55    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     71%          17
                        75%               84                   2.2                                 75%                    89               2.2         75%             92               2     75%      94                      1.8        25%           70    64   61         58                   55    55    55   55    55    55

                                                                                                                                                                                                                                                                                                                                                                                     75%          17
                        76%               84.5                 2.4                                 76%                   89.5              2.2         76%            92.5              2     76%     94.5                     1.8        30%           72    65   62         59                   55    55    55   55    55    55                                                   76%          18
                        80%                86                  2.4                                 80%                    91               2.2         80%             93               2     80%      94                      1.8        35%           74    66   63         60                   56    55    55   55    55    55                                                   80%          18
                        81%               86.5                 2.4                                 81%                   91.5              2.2         81%            93.5              2     81%     94.5                     1.8        40%           75    66   63         60                   56    55    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     81%          19
                        85%               89                   2.4                                 85%                    92               2.2         85%             94               2     85%      95                      1.8        45%           78    68   66         62                   58    55    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     85%          19
                        86%               89.5                 2.6                                 86%                   92.5              2.4         86%            94.5              2     86%     95.5                     1.8        50%           80    70   67         64                   60    55    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     86%          20
                        90%               92                   2.6                                 90%                    94               2.4         90%             95               2     90%      96                      1.8        55%           81    71   68         65                   61    55    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     90%          20
                        91%               92.5                 2.6                                 91%                   94.5              2.6         91%            95.5              2.2   91%     96.5                     2          60%           83    73   70         67                   63    58    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     91%          21
                        95%               95                   2.6                                 95%                    96               2.6         95%             97               2.2   95%      97                      2          65%           85    75   72         69                   65    60    55   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     95%          21
                        96%               95.5                 2.6                                 96%                   96.5              2.6         96%            97.5              2.2   96%     97.5                     2          70%           87    77   74         71                   67    62    57   55    55    55
                                                                                                                                                                                                                                                                                                                                                                                     96%          22
                       100%               98                   2.6                                100%                    98               2.6         100%            98               2.2   100%     98                      2          75%           89    79   76         73                   69    65    59   55    55    55                                                  100%          22
                                                                                                                                                                                                                                          80%           91    81   78         75                   71    66    61   55    55    55
                   Additional numbers added in from original tables to facilitate percentage or curve number rounding.
                                                                                                                                                                                                                                          85%           92    82   79         76                   72    67    62   55    55    55

                                                                                                                                                                                                                                          90%           94    84   81         78                   74    70    65   59    55    55
Green Roof Curve Number Credits                                                                                                                  Rev                                                                                      95%           96    87   84         81                   77    73    69   63    57    55
Roof Thickness                0                    2                    3                4                  6                       8            A                           0.38                                                        100%           98    89   86         83                   80    76    72   66    59    55
Effective RCN                 0                   94                   92               88                 85                      77            B                           0.26

                                                                                                                                                 C                           0.13
Permeable Pavement Curve Number Credits                                                                                                          D                           0.07
                                                                                                                                                                                                                                                                         Hydrologic Soil Group C
                         Effective Curve Number based on soil type
Thickness          A                B              C                                                                                                                                                                                       %I          RCN*    1   1.2        1.4                  1.6   1.8    2   2.2   2.4   2.6
              0                  0              0                       0                                                                                                                                                                 0%            74    70   70         70                   70    70    70   70    70    70
              6                 76             84                      93                                                                                                                                                                 5%            75    70   70         70                   70    70    70   70    70    70
              9                 62             65                      77                                                                                                                                                                 10%           76    70   70         70                   70    70    70   70    70    70
             12                 40             55                      70                                                                                                                                                                 15%           78    70   70         70                   70    70    70   70    70    70
                                                                                                                                                                                                                                          20%           79    70   70         70                   70    70    70   70    70    70
N-1 Rooftop Disconnection P E Credits                                                                                                                                                                                                     25%           80    72   70         70                   70    70    70   70    70    70
                                                 Disconnection Flow Path Length (ft)                                                                                                                                                      30%           81    73   72         71                   70    70    70   70    70    70
Western Shore                   0                  15                  30               45                  60                     75                                                                                                                  35%    82   74         73                   72    70    70   70    70    70    70
Eastern Shore                   0                  12                  24               36                  48                     60                                                                                                                  40%    84   77         75                   73    71    70   70    70    70    70
PE                              0                 0.2                 0.4              0.6                 0.8                      1                                                                                                                  45%    85   78         76                   74    71    70   70    70    70    70
                                                                                                                                                                                                                                          50%           86    78   76         74                   71    70    70   70    70    70
N-2 Disconnection of Non-Rooftop Runoff                                                                                                                                                                                                   55%           86    78   76         74                   71    70    70   70    70    70
                                                   Ratio of Disconnection Length to Contributing Length                                          Yes                                                                                      60%           88    80   78         76                   73    71    70   70    70    70
Impervious Ratio                0                0.2                  0.4             0.6                  0.8                      1            No                                                                                       65%           90    82   80         77                   75    72    70   70    70    70
Pervious Ratio                  0                0.1                  0.2             0.3                  0.4                    0.5            N/A                                                                                      70%           91    82   80         78                   75    72    70   70    70    70
PE                              0                0.2                  0.4             0.6                  0.8                      1                                                                                                     75%           92    83   81         79                   75    72    70   70    70    70
                                                                                                                                                                                                                                          80%           93    84   82         79                   76    72    70   70    70    70
N-3 Sheet Flow to Conservation Areas                                                                                                                                                                                                      85%           94    85   82         79                   76    72    70   70    70    70
                  Minimum Conservation Area Width                                                                                                                                                                                         90%           95    86   83         80                   77    73    70   70    70    70
Min. Width                     0             50                         75             100                                                                                                                                                95%           97    88   85         82                   79    75    71   70    70    70
PE                             0            0.6                        0.8               1                                                                                                                                               100%           98    89   86         83                   80    76    72   70    70    70



                                                                                                                                                                                                                                     Hydrologic Soil
                                                                                                                                                                                                                                        Group D
                                                                                                                                                                                                                                           %I          RCN*   1    1.2        1.4                  1.6   1.8   2    2.2   2.4   2.6

                                                                                                                                                                                                                                          0%            80    77   77         77                   77    77    77   77    77    77


                                                                                                                                                                                                                                          5%            81    77   77         77                   77    77    77   77    77    77


                                                                                                                                                                                                                                          10%           82    77   77         77                   77    77    77   77    77    77


                                                                                                                                                                                                                                          15%           83    77   77         77                   77    77    77   77    77    77


                                                                                                                                                                                                                                          20%           84    77   77         77                   77    77    77   77    77    77
                                                                                                                                                                                                                                          25%           85    78   77         77                   77    77    77   77    77    77
                                                                                                                                                                                                                                          30%           85    78   77         77                   77    77    77   77    77    77
                                                                                                                                                                                                                                          35%           86    79   78         78                   77    77    77   77    77    77
                                                                                                                                                                                                                                          40%           87    82   81         79                   77    77    77   77    77    77
                                                                                                                                                                                                                                          45%           88    82   81         79                   78    77    77   77    77    77

                                                                                                                                                                                                                                          50%           89    83   82         80                   78    77    77   77    77    77


                                                                                                                                                                                                                                          55%           90    84   82         80                   78    77    77   77    77    77


                                                                                                                                                                                                                                          60%           91    85   83         81                   78    77    77   77    77    77




                                                                                                                                                                                                                                          65%           92    85   83         81                   78    77    77   77    77    77

                                                                                                                                                                                                                                          70%           93    86   84         81                   78    77    77   77    77    77

                                                                                                                                                                                                                                          75%           94    86   84         81                   78    77    77   77    77    77

                                                                                                                                                                                                                                          80%           94    86   84         82                   79    77    77   77    77    77

                                                                                                                                                                                                                                          85%           95    86   84         82                   79    77    77   77    77    77
                                                                                                                                                                                                                                          90%           96    87   84         82                   79    77    77   77    77    77
                                                                                                                                                                                                                                          95%           97    88   85         82                   80    78    77   77    77    77
                                                                                                                                                                                                                                         100%           98    89   86         83                   80    78    77   77    77    77

				
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