Worksheet 2
Directly Connected Impervious Area (DCIA)
Project Tracking #:
Date:
This worksheet is a tool designed to help the designer maximize the advantages of incorporating disconnected impervious area into the design.
Employing non-structural stormwater management alternatives to minimize the effects of postdevelpment conditions stormwater runoff may result in a
reduction of structural stormwater management facilities and therefore a reduction in project cost.
Submit a single Worksheet 2 for each project site. List information for each area draining to an SMP or bypassing the SMP(s) separately. All area
within the limits of earth disturbance should be accounted for within the listed drainage areas. The drainage area labels used in the table should be
consistent with those used on plan sheets. Additional worksheets may be submitted if there are more than 10 drainage areas in the proposed condition.
Note: Drainage area boundaries may extend beyond the limits of earth disturbance. Only impervious area within the limits of earth disturbance,
excluding any public right-of-way area, should be included in the tables (Columns 5 through 17).
Cell Color Coding Key: Blank or Black - Designer Input; Red - Calculated by Spreadsheet; Blue - Populated by Spreadsheet
Site Information
1a. Development Type:
1b. Watershed:
1c. Public Sewer Type:
1d. Flood Management District:
2. Total Earth Disturbance Area (LOD)
sf…… Total area where activity will move or change the surface of the land,
including public right-of-way.
sf…… Total area where activity will move or change the surface of the land,
3. On-Site Earth Disturbance Area
excluding public right-of-way.
sf…… Total existing impervious area within the earth disturbance area,
4. On-site Existing Impervious Area
excluding public right-of-way.
Total Post-Development Impervious Area
This table itemizes all impervious cover areas within the LOD before disconnected impervious areas are applied. All green roof and porous pavement areas
must be included in this table.
SMP/Bypass Drainage Area
5. Post-Development
Roof Area (sf)
Total
0
6. Post-Development Ground
Level Impervious Area (sf)
7. Total Post-Development
Impervious Area (sf)
0
0
0
0
0
0
0
0
0
0
0
0
Disconnected Impervious Cover Areas (DIC)
See Section 3.2 of the Stormwater Management Guidance Manual for more information on disconnected impervious cover.
SMP/Bypass Drainage Area
Total
Roof-Level DIC
8. Disconnected
9. Green Roof
Roof Area (sf)
Area (sf)
0
0
Ground-Level DIC
10. Porous Pavement 11. Disconnected Pavement
Area (sf)
Area (sf)
0
0
12. Total DIC
Area (sf)
0
0
0
0
0
0
0
0
0
0
0
Version 3.0 Last Modified 7/1/2015
Worksheet 2
Directly Connected Impervious Area (DCIA)
Project Tracking #:
Date:
Disconnected Impervious Cover (DIC): Tree Disconnection Credits
Tree disconnection credit area may only be applied to ground-level DCIA within the limits of earth disturbance. See Section 3.2 of the Stormwater Management
Guidance Manual for more information. See Appendix I of the Manual for lists of approved and prohibited tree species.
SMP/Bypass Drainage Area
13. Number of New Trees
Total
14. New Tree
Disconnection Credit
Area (sf)
15. Existing Tree
Disconnection
Credit/Canopy
Area (sf)
0
0
0
0
0
0
0
0
0
0
0
0
16. Total Tree
Disconnection
Credit Area (sf)
17. Adjusted
Total Tree
Disconnection
Credit Area (sf)
0
0
0
0
0
0
0
0
0
0
0
0
0
Total Disconnected Impervious Cover (DIC) and Directly Connected Impervious Area (DCIA)
18. Total Ground-Level DIC
19. Total Roof-Level DIC
20. Total DIC
0 sf………
0 sf………
0 sf………
Sum of Columns 10, 11, and 17.
21. Total Ground-Level DCIA
22. Total Roof-Level DCIA
23. Total DCIA
0 sf………
0 sf………
0 sf………
Column 6 - Line 18 (Total Ground-Level DIC)
Sum of Columns 8 and 9
Sum Line 18 &19 (Total Roof-Level & Ground-Level DIC)
Column 5 - Line 19 (Total Roof-Level DIC)
Column 7 - Line 20 (CANNOT BE NEGATIVE) & should = Line 21 + Line 22
The DCIA value should be used only for Water Quality and Channel Protection calculations. Flood Control calculations should be based on actual surface types
and include all contributing areas.
When infiltration is infeasible for all or a portion of the Water Quality Volume (WQv), 100% of the WQv that is not infiltrated must be routed through an acceptable
pollutant-reducing practice. See Table 3.2-2 in Section 3.2 for a list of acceptable practices.
Redevelopment Percent Reduction in Impervious Area
Projects are exempt from the Channel Protection and Flood Control requirements if the total post-development DCIA within the
limits of earth disturbance (excluding public right-of-way) is at least 20% less than predevelopment impervious area.
24. Percent Reduction in Impervious Area
0 %...... ((Line 4 - Line 23)/Line 4) x 100%
Percent Disconnection of Post-Development Impervious Area
Redevelopment projects that disconnect at least 95% of the post-development impervious area and are exempt from the Channel
Protection and Flood Control requirements are eligible for PWD Stormwater Plan Review's expedited Disconnection Green
expedited review. Refer to Section 2.4 of the Manual.
25. Percent disconnected post-development impervious area
0 %..............(Line 20/Column 7 Total) x 100%
Surface Green Review Eligibility
Development projects that proposed to manage 100% of the first 1.5 inches of runoff from all post-development impervious area
through a combination of disconnection practices and bioretention/bioinfiltration basins are eligible for PWD Stormwater Plan
Review's expedited Surface Green Review. Refer to Section 2.4 of the Manual.
26. DCIA proposed to be managed by bioretention/bioinfiltration
sf
27. Post-development impervious area managed to meet the Surface Green Review requirement
0%
((Line 26+ Line20)/Column 7 Total) x 100%
Eligibility: This project is not eligible for the expedited Surface Green Review.
Proceed to Worksheet 3A. Complete one Worksheet 3A for each SMP.
Version 3.0 Last Modified 7/1/2015