1. INTRODUCTION
The Red Hook Wastewater Resource Recovery Facility (WRRF) serves as a cornerstone of the New York City Department of Environmental Protection’s (NYC DEP) wastewater infrastructure for northwestern Brooklyn. Commissioned in 1987, it is one of the 14 treatment plants comprising the city’s vast water resource recovery network. While it carries the “Red Hook” name due to its primary sewershed, the physical plant is strategically situated near the Brooklyn Navy Yard in the Vinegar Hill neighborhood, treating a design dry weather flow of 60 million gallons per day (MGD).
As a critical asset located directly on the East River waterfront, the Red Hook WRRF has become a focal point for urban climate resiliency engineering. following the devastating impacts of Superstorm Sandy in 2012. The facility represents a blend of conventional secondary treatment technologies and modern adaptation strategies, managing wastewater for approximately 200,000 residents while adhering to strict State Pollutant Discharge Elimination System (SPDES) requirements. Today, the plant stands as a case study in retrofitting mid-sized urban treatment facilities for climate resilience while maintaining operational continuity in a dense metropolitan environment.
2. FACILITY OVERVIEW
A. Service Area & Coverage
The Red Hook WRRF services a diverse urban catchment area of approximately 3,185 acres in Northwestern Brooklyn. The sewershed includes high-density residential neighborhoods such as Brooklyn Heights and Park Slope, mixed-use areas in Boerum Hill, and industrial zones along the Gowanus Canal and Red Hook waterfront. The collection system is primarily a Combined Sewer System (CSS), meaning the plant must manage significant flow variability during precipitation events. The drainage area relies on several major pump stations, including the Gowanus Pump Station, to convey flow to the treatment works.
B. Operational Capacity
The facility is rated for a dry weather design capacity of 60 MGD. During wet weather events, the plant is designed to handle up to 2x its design dry weather flow (approximately 120 MGD) through primary treatment and disinfection to mitigate Combined Sewer Overflows (CSOs). Historical flow trends indicate an average daily flow ranging between 30 and 45 MGD, suggesting adequate dry-weather reserve capacity. However, peak hydraulic loading during storm events remains a critical operational parameter, necessitating robust flow throttling and bypass management protocols.
C. Discharge & Compliance
Treated effluent is discharged into the East River, a tidal strait connecting Upper New York Bay and Long Island Sound. Compliance is monitored under the New York State Department of Environmental Conservation (NYSDEC). Key compliance parameters include Carbonaceous Biochemical Oxygen Demand (CBOD), Total Suspended Solids (TSS), pH, Settleable Solids, and Fecal Coliform. The facility operates under strict Total Maximum Daily Load (TMDL) constraints for nitrogen to protect the water quality of the Long Island Sound and New York Harbor estuary.
3. TREATMENT PROCESS
The Red Hook WRRF utilizes a conventional Step Aeration Activated Sludge process, the standard configuration for the majority of NYC DEP’s facilities due to its efficiency in footprint-constrained urban sites.
A. PRELIMINARY TREATMENT
Raw influent enters the headworks where it undergoes physical screening to protect downstream pumps and process equipment. The facility employs mechanical bar screens to remove large debris (rags, plastics, wood). Following screening, flow enters aerated grit chambers where velocity is reduced to allow inorganic solids (sand, gravel, coffee grounds) to settle while keeping organic matter in suspension. The removed grit and screenings are washed, compacted, and hauled off-site to landfills.
B. PRIMARY TREATMENT
Wastewater flows into rectangular primary settling tanks. Here, the velocity is further reduced, allowing approximately 60-70% of Total Suspended Solids (TSS) and 30-40% of BOD to settle as primary sludge. Floating grease and oils are skimmed from the surface. The primary sludge is collected via chain-and-flight mechanisms and pumped to the solids handling train.
C. SECONDARY TREATMENT (Step Aeration)
The biological treatment phase utilizes the Step Aeration Activated Sludge process. In this configuration, primary effluent is introduced at multiple points along the length of the aeration tanks, while Return Activated Sludge (RAS) enters at the head of the tank. This distribution evens out the oxygen demand across the basin, preventing localized hypoxia and allowing for higher organic loading rates compared to plug-flow systems.
Aeration System: The tanks are equipped with diffusers providing oxygen for the microbial biomass. Air is supplied by large centrifugal blowers housed in the main pump and power building.
Secondary Clarification: The mixed liquor flows to final settling tanks where the biological floc separates from the treated water. A portion of the settled sludge is returned to the aeration tanks (RAS), while the excess biomass is removed as Waste Activated Sludge (WAS).
D. DISINFECTION
The clarified effluent undergoes disinfection using Sodium Hypochlorite (liquid chlorine solution). The facility utilizes contact tanks designed to provide sufficient detention time (typically 15-30 minutes at peak flow) to ensure pathogen inactivation before discharge into the East River. Residual chlorine is monitored to ensure it meets SPDES limits.
E. SOLIDS HANDLING
Red Hook WRRF processes solids on-site but operates within the larger NYC integrated biosolids management plan.
- Thickening: Combined primary and secondary sludge is thickened, typically using gravity thickeners, to increase solids concentration and reduce volume.
- Digestion: The facility operates anaerobic digesters. These enclosed tanks maintain mesophilic temperatures (approx. 95°F) to break down volatile solids, reducing sludge volume and pathogen content while producing methane gas (biogas).
- Dewatering: Digested sludge is dewatered using centrifuges to produce a “cake” suitable for transport.
- Disposal: The biosolids cake is transported off-site for beneficial reuse (such as soil amendment or landfill cover) or disposal, managed by centralized NYC DEP contracts.
4. INFRASTRUCTURE & FACILITIES
A. Physical Plant
The site is characterized by its compact, urban footprint. Unlike sprawling suburban plants, Red Hook utilizes shared walls and vertical integration where possible. The architecture features the distinct brick styling common to NYC municipal infrastructure of the 1980s, designed to blend somewhat with the industrial aesthetic of the Navy Yard district.
B. Odor Control
Given the facility’s location adjacent to the rapidly developing Navy Yard and residential Vinegar Hill, odor control is a paramount operational priority. The plant employs carbon absorption systems and chemical scrubbers at high-odor generation points, including the headworks, thickeners, and sludge loading docks. The “stack” visible at the plant is part of the ventilation and dispersion system designed to minimize ground-level impact.
C. Energy Systems
The facility is a major energy consumer, with aeration blowers and main sewage pumps being the primary loads. NYC DEP has implemented aggressive energy management strategies, including the utilization of digester gas (biogas) in boilers to heat the digesters and facility buildings, offsetting natural gas consumption.
5. RECENT UPGRADES & MAJOR PROJECTS
NYC DEP Resiliency Program (Post-Sandy) – Approx. $15-25 Million
Project Context: During Superstorm Sandy (2012), the Red Hook WRRF, like many NYC waterfront assets, faced significant storm surge risks. The East River surged, threatening electrical substations and pump galleries.
Scope of Improvements:
- Flood Protection: Installation of flood-proof doors and barriers at critical building entry points.
- Equipment Hardening: Elevation of critical electrical distribution equipment, switchgear, and backup generators above the FEMA 100-year flood elevation plus freeboard.
- Pumping Systems: Installation of submersible pumps capable of operating even if dry wells are compromised.
- Sealing: Watertight sealing of wall penetrations and conduit entry points to prevent subterranean water ingress.
State of Good Repair & Energy Efficiency
Ongoing capital projects focus on replacing aging mechanical components from the original 1987 installation. This includes:
- Upgrades to main sewage pumps and motors with Variable Frequency Drives (VFDs) for better process control and energy savings.
- Replacement of centrifuge thickening equipment to improve solids capture rates.
- LED lighting retrofits across the facility to reduce base electrical load.
6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE
A. Permit Requirements
The facility operates under a NYSDEC SPDES permit. Strict limits are placed on:
- TSS & BOD5: Standard secondary treatment requirement of 30 mg/L (monthly average) and 85% removal efficiency.
- Nitrogen: As part of the Long Island Sound Nitrogen TMDL, the plant contributes to the aggregate load reduction goals for the East River zone.
B. CSO Management
The Red Hook sewershed is a major contributor to Combined Sewer Overflows. The NYC DEP “Long Term Control Plan” (LTCP) for the Gowanus Canal and East River involves strategies to maximize flow to the Red Hook WRRF during storms. This includes bending weirs and optimizing pump station logic to treat as much wet weather flow as possible before bypassing occurs.
7. CHALLENGES & FUTURE PLANNING
A. Climate Change & Sea Level Rise
As a waterfront facility, Red Hook faces the dual threat of rising sea levels (threatening hydraulic grade lines and gravity discharge) and increased precipitation intensity (overwhelming the combined sewer system). Future planning integrates “Cloudburst” management strategies in the sewershed to detain water before it reaches the plant.
B. Gowanus Canal Superfund Interaction
The Gowanus Canal, a federal Superfund site, lies within the Red Hook WRRF catchment area. EPA mandates regarding CSO reductions into the canal directly impact the operational strategy of the Red Hook facility. This includes the construction of future CSO retention tanks (e.g., the RH-034 and OH-007 tanks) which will store excess flow during storms and pump it to the Red Hook WRRF for treatment once capacity becomes available.
8. TECHNICAL SPECIFICATIONS SUMMARY
| Parameter | Specification |
|---|---|
| Facility Type | Secondary Treatment (Activated Sludge) |
| Operating Authority | NYC DEP (Bureau of Wastewater Treatment) |
| Year Commissioned | 1987 |
| Design Capacity (Dry) | 60 MGD |
| Wet Weather Capacity | ~120 MGD (2x Dry Flow) |
| Process Technology | Step Aeration Activated Sludge |
| Disinfection | Sodium Hypochlorite (Chlorination) |
| Solids Handling | Anaerobic Digestion, Centrifuge Dewatering |
| Receiving Water | East River (Class I Saline Surface Water) |
| Collection System | Combined Sewer System (CSS) |
| Staffing | ~50-60 (Operations, Maintenance, Admin) |
9. FAQ SECTION
Technical Questions
1. Does the Red Hook WRRF perform nutrient removal?
While the plant performs carbonaceous removal (BOD), it is not a designated Biological Nutrient Removal (BNR) facility in the same capacity as plants discharging into Jamaica Bay. However, it operates under aggregate nitrogen load limits for the East River/Long Island Sound TMDL.
2. How are biosolids managed at Red Hook?
Solids are thickened and digested anaerobically on-site. The resulting sludge is dewatered via centrifuges. NYC DEP typically manages the final biosolids product through contracts for land application or landfilling outside the city limits.
3. How does the plant handle wet weather flows?
The plant can hydraulically pass up to twice its design dry weather flow. Flows exceeding this capacity in the collection system may discharge via Combined Sewer Overflow (CSO) outfalls to prevent treatment process washout and basement backups.
Public Interest Questions
4. Does the Red Hook plant smell?
Like all wastewater facilities, odors are generated. However, the plant utilizes enclosed tanks and activated carbon scrubbing towers to treat foul air before it is released. Odor complaints are tracked closely by NYC DEP.
5. Can the public tour the Red Hook WRRF?
Generally, the facility is closed to the public for security and safety reasons. However, NYC DEP occasionally offers tours for educational groups, universities, or during special events like “Open House New York” (though the Newtown Creek facility is more commonly used for tours).