Sulekha GangopadhyayCapstone PresentationFall 2017

Green Roofs and CSO Mitigation:

Evaluating green infrastructure expansion in partnership with Newtown Creek Alliance

Kingsland Wildflowers Green Roof Brooklyn, NYC

- Newtown Creek is a designated Superfund waterway in New York City, located along the border of Queens and Brooklyn counties, and connected to the East River.

- Contaminants include industrial waste, raw sewage, oil, and street trash. The sewage problem is due to the number of combined stormwater sewage outfalls emptying into the Creek.

- Newtown Creek Alliance (NCA) is a local environmental organization working on remediation of the Creek and facilitating public environmental education and community engagement with local waterways.

Introduction: Pollution in Newtown Creek

[NYS Department of Health] [Newtown Creek Alliance]

In older cities like New York, water from storm events exceed sewer system capacity, and due to the combined stormwater and sewage system, flow untreated into city waterways.

Green Infrastructure (rain gardens, bioswales, green roofs, porous streets and sidewalks, etc) may be utilized to mitigate combined sewer outflow (CSO).

CSO and Urban Systems

[NYC DEP]

[CUNY Graduate Center Academic Commons]

Combined Sewer Overflow Diagram

[Newtown Creek Alliance]

[NYC DEC]

Sewage Outfalls and Water Quality

Organisms from Newtown Creek (Ecological Restoration Project)Algal blooms in Newtown Creek due to CSO

[Newtown Creek Alliance]

[NYC DEP]

NYC DEP Green Infrastructure Typology Recommendations

[Philadelphia Water Department]

Visual Representation of Forms of Green Infrastructure

Green Infrastructure Section of NYC DEP Long Term Control Plan:

- 83 million gallons per year (MGY) reduction from GI planned or implemented in the Newtown Creek Long Term Control Plan (LTCP)

- Program implementation through 2030

- However, NC-077 as 1 outfall alone produces about 300 MGY per year (NYC DEP LTCP).

NYC DEP Outfall Map

Area of Interest: Maspeth

- Combined Sewer Outfall sewer shed on Maspeth side of Newtown Creek- Maspeth area outfall NC-077 (1 of the top 3 outfalls with high volume of discharges)- CSO outfall NC-077 in the Maspeth section of Newtown Creek has roughly 41 CSO

events and about 300 million gallons of stormwater discharge per year

[Open Sewer Atlas]

Outfall NC-077

[Oasis NYC]

Zoning Category: Industrial

Project Introduction:

- Developing building selection framework for implementation of industrial green roofs in Maspeth, Queens region in order to supplement the green infrastructure projects in the NYC DEP Long Term Control Plan

- Calculation of total stormwater diversion from CSO through green roof implementation- Policy recommendations

[Newtown Creek Alliance]

Benefits of Green Roofs

- Insulation- Energy savings- Habitat- Provide cooling- Reduce smog- Absorb rainwater

[Hazen and Sawyer Environmental Engineers]

Existing Industrial Green Roof Example in Brooklyn - Kingsland Wildflowers

Benefits:

- Absorbs stormwater

- Provides habitat for native flora and fauna

- Provides a venue for educational and community events

Financing

- NYC Green Roof Tax Abatement (GRTA) fiscal incentive- NYC DEP Green Infrastructure Grant Program - upfront cost

can be a disincentive, as the grant is dispensed through reimbursement

[Newtown Creek Alliance]

[NYC DEP]]

Drainage Typology

Potential Industrial Green Roof Areas - Maspeth Region

[Newtown Creek Alliance]Recreated GIS figure of Maspeth lot areascontaining rooftops identified via NYC

How Much Stormwater Diversion is Possible?

- Mapping prospective rooftop locations to supplement DEP Long Term Control Plan GI projects requires identifying sewer system boundaries in the area.

- Calculations involve water retention figures based on lightweight soil medium depth, selected according to building roof load bearing and cost, and total area of green roof surface.

[Google Maps]

Climate models indicate that annual average precipitation in New York State will increase by 1-8% by 2020, and the number of heavy rainfall events will increase as well.

The number of days over 1 inch of rainfall in New York City is expected to be roughly 13 in the 2020s, and roughly 3 for rainfall over 2 inches (ClimAID, NYSERDA).

Precipitation Patterns

Absorption Capacity of Soil Medium

A 2-inch rain event would create 1,667 cubic feet or 12,470 gallons of rainwater per 10,000 square foot of green roof (1/6 of a foot of rain multiplied by 10,000 feet of area = 1,667 cubic feet). This is roughly half of total soil capacity.

Since 1 cubic foot of soil material can absorb up to an almost 4" storm, 6 inches of this medium is adequate for approximately a 2” rain event.

1 cubic foot of lightweight green roof medium could potentially hold 0.33 cubic feet or 2.4 gallons of water (Professor Paul Mankiewicz, 12/7/17)

Therefore, 10,000 square feet of medium at this thickness could capture a maximum of 24,000 gallons of stormwater.

The total amount of available roof space in Maspeth is roughly 5,893,077 square feet (NYC MapPLUTO). A two-inch rain event would produce about 982,180 gallons (1/6 foot of rain multiplied by 2,893,077 square feet) of water total across this area, which would then be easily accommodated by 6-12” of the growing medium and diverted from the combined sewer outfall.

This amount of capture would amount to about 13.4% diversion. However, an additional consideration is space limitations on some roofs due to other uses, and NCA will focus on industrial roof spaces above 10,000 square feet in Maspeth.

Stormwater Diversion from Green Roof Implementation in Maspeth

CSO outfall NC-077 in the Maspeth section of Newtown Creek has roughly 41 CSO events per year, and an outflow of roughly 300 million gallons per year, averaging out to about 7,317,073 million gallons per event.

Accompanying strategies to achieve greater stormwater diversion include:

- Increasing outreach and public engagement in order to facilitate greater participation in green roof implementation projects

- Changing the reimbursement method of delivering the GI grant in order to incentivize property owners

- Implementation of a stormwater fee based on level of runoff created by impermeable surfaces on individual properties, and refining standards for new construction.

Conclusion and Recommendations

[Newtown Creek Alliance]

Thank You

[Newtown Creek Alliance]

City of New York. (2017). NYC Open Data. Retrieved from: https://opendata.cityofnewyork.us/

Daniel J. Bliss, Ronald D. Neufeld, and Robert J. Ries. Stormwater Runoff Mitigation Using a Green Roof. Environmental Engineering Science. February 2009, 26(2): 407-418. https://doi.org/10.1089/ees.2007.0186.

Enman, S. (2017). Newtown Creek: How to fix the combined sewage overflow problem. The Brooklyn Eagle.

EPA. (2017). Superfund Site: Newtown Creek. Retrieved from: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0206282

Horton, R., D. Bader, C. Rosenzweig, A. DeGaetano, and W.Solecki. 2014. Climate Change in New York State: Updating the 2011 ClimAID Climate Risk Information. New York State Energy Research and Development Authority (NYSERDA), Albany, New York.

Mankiewicz, P. (2009). Green Roofs and Local Temperature. Living Architecture Monitor. Volume 11, No. 1.

Mentens, J, Raes D., Hermy, M. (2006) “Green roofs as a tool for solving the rainwater runoff problem in the urbanized 21st century?” Landscape and Urban Planning. Volume 77, Issue 3.

Navarro, M. (2010). Exxon Mobil Settles State Suit on Newtown Creek Cleanup. New York Times. Retrieved from: http://www.nytimes.com/2010/11/18/nyregion/18newtown.html?mcubz=0

New York DEC. (2017). Retrieved from: www.dec.ny.gov

NYC DEP. (2017). Newtown Creek CSO Long Term Control Plan. Retrieved from: http://www.nyc.gov/html/dep/html/cso_long_term_control_plan/newtown_creek_ltcp.shtml

Newtown Creek Alliance (2017) Retrieved from: www.newtowncreekalliance.orgNYC Oasis. Retrieved from: http://www.oasisnyc.net/map.aspx

NYC Solar Map. Retrieved from: https://www.nysolarmap.com/

NYC Dept. of Buildings. (2017). Retrieved from: https://www1.nyc.gov/site/buildings/business/green-roofs.page

NYC DEC. (2017). Stormwater. Retrieved from: http://www.dec.ny.gov/chemical/8468.html

Sources

NYC Dept. of Planning (2017). North Brooklyn Industry Plan. Retrieved from: https://www1.nyc.gov/site/planning/plans/north-brooklyn-vision-plan/north-brooklyn-vision-plan-updates.page

NYC Dept. of Planning (2017). NYC MapPLUTO. Retrieved from: https://www1.nyc.gov/site/planning/data-maps/open-data.page

NYC Parks (2013). Green Roofs. Retrieved from: https://www.nycgovparks.org/pagefiles/53/Citywide-Services-Green-Roof_2.pdf

Northeast Regional Climate Center. (2017). Cornell. Retrieved from: http://www.nrcc.cornell.edu/

City of New York. (2017). NYC Open Data. Retrieved from: https://opendata.cityofnewyork.us/

Open Sewer Atlas NYC. (2017). Retrieved from www.openseweratlas.tumblr.com

Philadelphia Water Department. (2017). Stormwater. Retrieved from: http://www.phila.gov/water/wu/stormwater/pages/default.aspx

Smith, P. (2013) The Toxins Lurking in Newtown Creek. New York Magazine. Retrieved from: http://nymag.com/news/intelligencer/newtown-creek-2013-12/

Stein, J. and Kuz, Z. (2016). Fluid Frontiers: Stormwater management research in the Red Hook Sewershed, Brooklyn. Pratt Institute.

Valderrama, A., Lochner, J., Koval, M. (2017). Catalyzing Green Infrastructure on Private Property: Recommendations for a Green, Equitable, and Sustainable New York City. NRDC. Retrieved from https://www.nrdc.org/sites/default/files/green-infrastructure-recommendations-at-a-glance.pdf

Wilson, W. (2016). Stormwater. University of Chicago Press.

[Newtown Creek Alliance]