2. Stormwater Management Design Criteria
Mitigate the peak rate of stormwater runoff to
pre-existing levels (Boston Water and Sewer
Commission requirement)
• 2- and 10-year storm events
Encourage groundwater recharge
(City of Boston requirement)
• Swales, Pervious Pavement, Perforated Pipes
Mitigate the project’s infrastructure costs
(Owner’s requirement)
• Strive for non-redundant systems
– i.e.: green roof versus below grade perforated
pipe detention system
3. Low Impact Development (LID) Initiatives
Jackson Square intends to utilize:
Green Roof Systems
Rain Gardens
Vegetated Swales
Pervious Pavements
4. Jackson Square – Existing Conditions
Columbus Avenue at Centre Street, Boston, MA
Site I: 60,287 sf CN=86
Site II: 216,929 sf CN=94
Site III: 212,187 sf CN=90
* Urban Fill – “D” Soils
5. Jackson Square – Conventional Utility Plan
Site I: 60,287 sf CN=94
Site II: 216,929 sf CN=95
Site III: 212,187 sf CN=91
1. Underground
detention systems
2. Conventional catch
basin & pipe systems
3. Conventional Roofs
6. Jackson Square – Proposed Green Improvements
Site I: 60,287 sf CN=88
Site II: 216,929 sf CN=89
Site III: 212,187 sf CN=87
1. 50%-75% Green roofs
2. Rain Gardens
3. Vegetated Swales
7. Comparing Design Alternatives
Curve Number (CN) Value Comparison:
Existing Conventional Green Roof
CN Value CN Value CN Value
Site I 86 94 88
Site II 94 95 89
Site III 90 91 87
8. Jackson Square LID Initiatives
Green Roof Systems Components of Green Roofs
Essential
Waterproofing Membrane
Root barrier
Drainage Layer
Filter Fabric
Growing Medium (Substrate)
Vegetation
Optional
Membrane Protection layer
Insulation
Water Retention Layer
Erosion Protection Layer
Irrigation System
Water Features, Walkways,
Curbs, Railings, Lighting
12. Any Questions?
THANK YOU!
Contact Information
John M. Schmid, P.E., Senior Project Manager
Nitsch Engineering
186 Lincoln Street, Suite 200
Boston, MA 02111
(617) 338-0063
jschmid@nitscheng.com
