OPEN SEWER ATLAS NYC A GIS EXPLORATION OF COMBINED SEWER INFRASTRUCTURE AND INTERVENTION STRATEGIES AT THE COMMUNITY SCALE

NYGEOCON 2015

Korin Tangtrakul

openseweratlas.tumblr.com

Project History – Red Hook BACKGROUND

COMBINED SEWER SYSTEM

70% About of the city’s sewershed

area is combined

WATER QUALITY IMPACT

SEWERSHED ISSUES

• Street flooding and

sewer backups

impacted the area.

• Through stakeholder

interviews, came to

realize these issues

were not isolated to

Hurricane Sandy!

HURRICANE SANDY – RED HOOK

• Data and maps on the

sewer system in Red

Hook was VERY

challenging to find.

RED HOOK SEWERSHED

• 311 complaints were

very easy to map and

showed consistent

sewer system issues.

CONSISTENT ISSUES IN RED HOOK

LACK OF DATA!

LACK OF DATA!

Open Sewer Atlas NYC is an

open data source for sewer

infrastructure and sub-

sewersheds or drainage areas

of interceptor sewer lines for

the priority sewersheds of

CSO-problem areas.

An exercise of GIS analysis to demystify New York City’s sewer system

WHAT IS OPEN SEWER ATLAS NYC?

Gowanus Newtown Creek Alley Creek Bronx River Jamaica Bay

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4 SCOPE OF WORK

• To better understand the

sewer system, we looked at

issues at the “sewershed”,

“sub-sewershed” and

“CSO-shed” level.

RED HOOK SEWERSHED

OPENSEWERATLAS.TUMBLR.COM/MAP

FINAL PRODUCTS

DRAINAGE AREAS

311 COMPLAINTS

LANDUSE

FINAL PRODUCTS

OSANYC WORKSHOP

• Bushwick and

surrounding

neighborhoods

• 2,275 acres

• Almost 200,000

people

NCB-015

NEWTOWN CREEK OUTFALL

• 570 million gallons of CSO discharge enters

Newtown Creek from NCB-015.*

• 0.4 inches of rainfall is enough to overload the

system and result in a combined sewer overflow.*

*Sources Sampling Approach Memorandum, Remedial Investigation/Feasibility Study, Newtown Creek

NCB-015

• Almost 90% of the

area is impervious*

*Calculated using 2010 LiDAR model of land cover

NCB-015

• Water consumption is about 20 million gallons

a day (25 million gallons with air conditioning).*

*Calculated using 2014 CEQR Technical

Manual, and assuming residential

consumption of 75 gallons/person/day

QUANTIFYING CSO

• Stormwater runoff is about 70 million

gallons in a 1.2 inch storm.*

*Calculated using 2010 land cover, assuming .2 runoff coefficient

for grass/shrub, .3 for bare earth, .95 for buildings and roads, and

.85 for tree canopy and other (assumed to be mostly sidewalk).

These runoff coefficients were found in NYC DEP’s green

infrastructure guidelines, 2012. According to DEP, 90% of storms

are 1.2 inches or less.

QUANTIFYING CSO

• Mitigating 45 million gallons of

stormwater/wastewater in a 1.2 inch

storm may prevent CSO from NCB-015.* *Assumes the current capacity manages about .4 inches of rain, or 21.2 million gallons of stormwater runoff.

QUANTIFYING CSO

QUANTIFYING IMPACT

• CSOs 101

• Green Infrastructure Grants

• Build-your-own Downspout

Planter

WORKSHOP SERIES

QUESTIONS?