Gowanus Canal Waterbody/Watershed Assessment … · Gowanus Canal Waterbody/Watershed Assessment...

Gowanus Canal Waterbody/Watershed Assessment and Preliminary Facility Plan

April 20, 2004

NYCDEP Bureau of Environmental Engineering 1


April 20, 2004


I )esignatcd Uses & Regulatory Issues

• Designated Use is Class SD - Fish Survival Dissolved Oxygen: Never-Less-Than 3.0 mgll No coliform bacteria standards

• New York State 303(d) List (2002, and Draft 2004) Use Affected: Pollutant: Source: Scheduled for TMDL

Fish Propagation Oxygen Demand Urban I Storm I CSO

• Waterbody Inventory I Priority Waterbody List (2002) Use Impairment: Severity: Pollutants:

Source:

• Aquatic Life, Recreation, Aesthetics Precluded, Impaired, Stressed [respectively] Oxygen Demand, Pathogens, Floatables, Odors, Oil and Grease, Nutrients

CSOs, sediment, urban runoff, stormwater, industrial


April 20, 2004



April 20, 2004


l"ield Investigations and Monitoring

• DEP Harbor Survey

• Applying Data from Past USA Project FSAPs 2001 Harbor-Wide lchthyoplankton 2001-2002 Harbor-Wide Epibenthic Recruitment and Survival 2002 Tributary Benthos Characterization

• FSAPs Specific to Gowanus Canal: 2003 Subtidal Benthos and lchthyoplankton Characterization 2003 Tributary Toxicity Characterization

2003 Bathymetry Survey

• 2003 USACE Ecosystem Restoration Investigations Benthic Sampling (ecological characterization) Sediment Sampling (chemical characterization) Subsurface Exploration

•

Data Review Zones

O • -2 -3 • • o s

Past and Present DEP Water Quality Monitoring

e 11"1"18f' Hatbot Plarriog (1989-1991)

• Ha-~(ongoing)

• Hs-~ Trlbulaoy Monilotlng (ongoing)

• Sentinel ~(ongoing)

A


April 20, 2004


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April 20, 2004



April 20, 2004


Preliminar\ Assessment Findings

• Water Quality At Head End Is Dominated By Flushing Tunnel Operation Water quality conditions in Gowanus Canal are dependent on those of New Yor1< Hamor,

especially atthe head end- effect is diminished moving downstream Sedimentation is significantly reduced at the head end by the induced currents of the Flushing

Tunnel- sediments are spread downstream instead of just at head end

• Water Quality Standards Compliance Dissolved Oxygen (Fishable)

Designated standards (Class SD) are met

Upgrade of standard to Class I rntty also he possih le

other state and federal exuosure~'duration criteria are most tv met

Total Coliform (Swimmable) Secondary contact recreation criteria are met

Primary contact recreation criteria are not met all the time

• Toxicity and Toxics Water column toxicity- negative Sedimenttoxicity- positive, indicating poor benthic conditions and habitat limitations Sediment contaminant concentrations are similar to New York Harbor waters and other

• tributaries 13

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• CSO Discharges Are A Small Component of Overall Dissolved Oxygen Deficit Gowanus Pump Station and other csos upstream of Hamilton Avenue account tor less than 1 mg/L of overall deficit at critical time (July)

• 100% CSO Abatement Wi II Not Achieve Exposure/Duration Criteria All The Time Implementing additional cso abatement controls will still not achieve the criteria

• 14


April 20, 2004


\VatcrbodY Vv'atcrshcd Planning . ~-

• Waterbody/Watershed Assessment Objectives: Integrate DEP planning programs/projects Coordinate with non-DEP activities Clearly define reasonably attainable waterbodylwatershed use goals Develop a preliminary waterbodylwatershed plan

• Assessment Findings Indicated That: Increasing pump station capacity improves CSO capture and reduces loads Increasing the Flushing Tunnel rate will improve overall water quality

conditions throughout Gowan us Canal

• USA Additional Engineering Analysis Focused On:

• Increasing pump station capacities further Constructing retention and instream facilities Additional low-cost retrofit and/or system adjustments Cost-effective floatables controls

16


April 20, 2004


\Vhat 1 s Attainable and Appropriate'?

• Juvenile And Adult Fish Survival Supported Most species avoid dissolved oxygen concentrations less than 3 mg/L Many will enter even if bottom concentrations are < 3 mg/L, if rest of water

column> 3 mg/L Improvements in water quality conditions are expected to increase abundance

and diversity of aquat1c life Gowan us Canal is not as ignificant resource for overall ecosystem

• Sediment Improvements More oxygenated sediments Greater benthic abundance and diversity Better food base for other aquatic I ife Less toxic

• Stakeholder Team Consensus for Secondary Contact Recreation

• Aesthetic Conditions Consistent with Planned and Proposed Increase in Access to Shorelines by Local Community

• 18


April 20, 2004



April 20, 2004


Additional Lngineering 1\lternati ves

• Constructing Retention Facilities Gowanus Pump Station

2nd Avenue Pump Station

• lnstream Alternatives lnstream Aeration

Dredging

• Increasing Pump Station Capacities Gowanus Pump Station

Nevins Street Pump Station 2nd Avenue Pump Station

• Additional Low-Cost Retrofit And/Or System Adjustments Weir Adjustments in Red HooY. and Owls Head WPCP Regulators

• Cost-Effective Floatables

• Modernizing Gowanus Canal Flushing Tunnel

Controls In-line and end-of-pipe netting systems Periodic skimmer vessel cleaning

• Cost Benefit !\ na 1 vsi s Retention

• Constructing Retention Facilities Can Attain 90% CSO Abatement Requires constructing two facilities at a cost nearing $200,000,000

Requires acquiring property and increasing long-term burden on local community

Will not fully achieve compliance with fishable/swimmable water quality standards

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21


April 20, 2004


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Sedimentation Distribution and Dredging

• Projected Benthic Habitat Improvements Gowan us Canal Flushing Tunnel operation upgrade minimizes the Total Organic

Carbon (TO C) content of the sediments in Gowan us Canal Minimizing TOC in sediments facilitates increased benthic taxa abundance

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April 20, 2004



April 20, 2004


Pn .. diminarv \Vat...:rbodv \Vatershed hwilit v . . Plan ( eonr)

• Modernize Gowanus Canal Flushing • Rehabilitate/Reconstruct OH-007 Tunnel Clean existing grit chamber and b<lffle

Modemized pumping system and add Inspect, evaluate & design improvements redundancy Reconstruct to facilitate maintenance Increase flushing rate Eliminate downtime

Reduces floatables discharges

Improves water quality conditions • Periodic Waterbody Floatables

Skimming • Bond-Lorraine Sewer Cleaning & When Gowan us Pump Station screening

Repair is exceeded Increase conveyance capacity Once/Twice per average year Reduces overflows Mal ntams aestnetl cs

• Regulator Weir Adjustments • Pursue Remedial Dredging with Raise weir at RH.035 USACE Reduces overflows Dredge to 6 feet below mean low water

($18,000,000 full cost) To restore habitat and improve

aesltletics (odors, exposed sediments)

• 27


April 20, 2004


Class SO Dissolved Oxygen Standard

100

to

§: 80

70 .. ... !! . !!! 50 c. E .., 0

30 ..,

Projection Seanario:

100% cso Abat.l'notl'll

20

10

0 I For an Average Precipitation Year

0 1000 1000 3000 4000 5000 S00C1 7000 8000 toOO

Gowanus Canal - Distance from Head (feet)


April 20, 2004


Basel me= 1985 Gowanus Pump Stat1on Improvements Facility Plan= Gowanus Canal Flush1ng Tunnel React1vat1on


April 20, 2004


J)J-:p· s Next Steps

• Implement Waterbody!Watershed Facility Plan

• Request Water Quality Standards Review and Revision by New York State Department of Environmental Conservation Review/revise aquatic life, recreation & aesthetics

Recommend consideration as an Urban Tributary with: Fishable dissolved oxygen standards

Secondary contact recreation

Aesthetics consistent with community needs

• Continue Local Sponsorship And Coordination With Ongoing U.S. Army Corps Of Engineers' Gowanus Canal Ecosystem Restoration Feasibility Study Identify opportunities/benefits of remediation to improve habitat

• 33

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