Hampton Roads Sanitation District Army Base Treatment Plant Norfolk

FACILITY BASIC INFORMATION

• Plant Name: Army Base Treatment Plant
• Location: Norfolk, Virginia
• Operating Authority: Hampton Roads Sanitation District (HRSD)
• Design Capacity: 18.0 MGD
• Current Average Flow: ~10-12 MGD
• Population Served: Serves significant portions of Norfolk and Naval Station Norfolk
• Service Area: City of Norfolk (West/North sectors), U.S. Naval Station Norfolk
• Receiving Water Body: Elizabeth River (flowing to Chesapeake Bay)
• NPDES Permit Number: VA0081256
• Year Commissioned: Original construction 1960s (Major upgrades ongoing)

1. INTRODUCTION

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The Army Base Treatment Plant is a critical infrastructure asset within the Hampton Roads Sanitation District (HRSD) portfolio, strategically located to serve the City of Norfolk and the world’s largest naval installation, Naval Station Norfolk. With a design capacity of 18.0 million gallons per day (MGD), this facility plays a pivotal role in protecting the water quality of the Elizabeth River and the lower Chesapeake Bay.

Operated by HRSD, a political subdivision of the Commonwealth of Virginia, the plant has evolved from a primary treatment facility into a sophisticated secondary treatment plant employing biological nutrient removal (BNR) to meet stringent Chesapeake Bay Total Maximum Daily Load (TMDL) requirements. Situated in a region facing significant sea-level rise challenges, the Army Base Treatment Plant is currently the focus of extensive resiliency planning and infrastructure hardening. It represents a model of municipal-federal cooperation, handling complex influent streams from both residential zones and dense military industrial operations.

2. FACILITY OVERVIEW

A. Service Area & Coverage

The Army Base Treatment Plant serves a highly urbanized and industrialized catchment area in Norfolk, Virginia. Unique among HRSD’s facilities, its service area includes Naval Station Norfolk, which houses a massive concentration of naval personnel, support facilities, and industrial ship-support operations. The collection system feeding the plant is characterized by a mix of municipal gravity lines and an extensive network of pump stations designed to navigate the flat, coastal topography of the Hampton Roads region.

B. Operational Capacity

The facility is permitted for a design flow of 18.0 MGD. Historical data indicates an average daily flow typically ranging between 10 and 12 MGD, providing the plant with adequate hydraulic buffer for wet weather events. However, due to the aging collection system in the older parts of Norfolk, the facility experiences significant peaking factors during storm events due to Inflow and Infiltration (I/I). The hydraulic peak capacity is designed to handle surges up to 35 MGD to prevent sanitary sewer overflows (SSOs).

C. Discharge & Compliance

Treated effluent is discharged into the Elizabeth River, a tidal estuary contributing to the Chesapeake Bay. The plant operates under VPDES Permit No. VA0081256, administered by the Virginia Department of Environmental Quality (DEQ). Compliance limits focus heavily on nutrients, specifically Total Nitrogen (TN) and Total Phosphorus (TP), in accordance with the Virginia Watershed General Permit Regulation for Nutrient Enriched Waters. The facility consistently meets these rigorous standards through advanced process control and chemical polishing.

3. TREATMENT PROCESS

The Army Base Treatment Plant utilizes a conventional activated sludge process modified for biological nutrient removal. The treatment train is designed to handle domestic wastewater as well as specific industrial loads associated with the naval base.

A. PRELIMINARY TREATMENT

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Raw influent enters the headworks where it passes through mechanical bar screens to remove large debris, rags, and plastics. Following screening, the flow enters aerated grit chambers. These systems reduce the velocity of the wastewater, allowing heavier inorganic materials (sand, gravel, coffee grounds) to settle while keeping organic matter in suspension. The removed grit is washed and dewatered before being hauled to a landfill. Odor control at the headworks is critical due to the plant’s proximity to active military and commercial areas; chemical scrubbers (typically utilizing sodium hypochlorite and caustic soda) are employed to neutralize hydrogen sulfide.

B. PRIMARY TREATMENT

Wastewater flows to primary clarifiers (circular configuration). Here, flow velocity is further reduced to allow settleable solids to drop to the bottom as primary sludge, while grease and oils float to the surface for skimming. The primary treatment stage typically removes 50-60% of Total Suspended Solids (TSS) and 30-35% of Biochemical Oxygen Demand (BOD), significantly reducing the organic load on the subsequent biological stage.

C. SECONDARY TREATMENT (Activated Sludge)

The biological heart of the plant consists of aeration basins configured for nutrient removal. The basins utilize fine-bubble diffusion to maximize oxygen transfer efficiency.
To meet Chesapeake Bay nutrient limits, the plant utilizes a configuration (such as MLE or Step-Feed) that incorporates anoxic zones. In these zones, nitrate produced during aeration is recycled and converted to nitrogen gas by denitrifying bacteria, significantly reducing Total Nitrogen levels. Ferric salts or alum are added to precipitate phosphorus, ensuring compliance with Total Phosphorus limits. Following aeration, the mixed liquor flows to secondary clarifiers where the biological biomass separates from the treated water.

D. DISINFECTION

The Army Base plant utilizes chlorination (using sodium hypochlorite) for disinfection to eliminate pathogenic organisms. Following the contact tanks, the effluent undergoes dechlorination (using sodium bisulfite) to remove residual chlorine, which is toxic to aquatic life, before the final discharge into the Elizabeth River.

E. SOLIDS HANDLING

As part of HRSD’s regional integration strategy, solids handling at the Army Base plant is minimized compared to standalone facilities. Primary and waste activated sludge (WAS) are thickened (often via gravity thickening or rotary drum thickeners) and pumped through HRSD’s extensive force main network to the Atlantic Treatment Plant or other regional processing centers for digestion, dewatering, and final disposal. This regional approach centralizes the production of Class A or Class B biosolids and allows for the generation of energy via biogas at the central processing hubs.

4. INFRASTRUCTURE & FACILITIES

A. Physical Plant

The site occupies a compact footprint adjacent to the Elizabeth River terminals and rail lines. The facility layout is dense, necessitating vertical integration and careful hydraulic profile management. Key structures include the Administration Building, Control Center, Headworks Building, and the Blower Building which houses the turbo blowers supplying air to the aeration basins.

B. Energy Systems

Energy management is a priority for HRSD. The Army Base plant has undergone retrofits to replace older centrifugal blowers with high-efficiency turbo blowers with air foil bearings, significantly reducing the electrical load required for aeration. Variable Frequency Drives (VFDs) are standard on all major pumps (influent, RAS, WAS) to match energy consumption with hydraulic demand.

C. Odor Control

Given the facility’s location near the Naval Station and commercial port operations, odor control is paramount. The plant utilizes dual-stage chemical scrubbers and activated carbon polishing units to treat foul air extracted from the headworks, primary clarifiers, and sludge holding tanks. Real-time H2S monitoring ensures that odor threshold limits remain compliant with community standards.

5. RECENT UPGRADES & MAJOR PROJECTS

Current Major Project: Boat Harbor and Army Base Interceptor Improvements

• Project Scope: Comprehensive rehabilitation and replacement of the interceptor force mains connecting the Army Base and Boat Harbor service areas. This includes upgrades to major pump stations to increase reliability and reduce SSO potential.
• Drivers: Aging infrastructure (some pipes >50 years old), consent decree compliance, and climate resiliency.
• Technical Highlights: Implementation of corrosion-resistant materials and smart-sewer sensors for real-time flow monitoring.

Nutrient Removal Optimization (2015-2020)

• Scope: Upgrades to the aeration control systems and chemical feed facilities to enhance nitrogen and phosphorus removal reliability.
• Result: Consistent compliance with the aggressive Chesapeake Bay Watershed Implementation Plan (WIP) targets.

Upcoming: Coastal Resiliency and Hardening (2024-2030)

• Context: The Hampton Roads region is experiencing some of the highest rates of relative sea-level rise on the U.S. East Coast.
• Scope: HRSD is implementing a district-wide resiliency plan. For Army Base TP, this involves elevating critical electrical switchgear, hardening perimeter flood walls, and installing flood-proof doors and barriers on critical process buildings.
• Budget: Part of a district-wide multi-billion dollar long-term capital plan.

6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

A. Permit Requirements

The facility operates under a VPDES permit that mandates strict control over conventional pollutants and nutrients. Key parameters include:

• BOD5: Monthly average limits typically < 30 mg/L (often achieving < 5 mg/L).
• TSS: Monthly average limits typically < 30 mg/L (often achieving < 5 mg/L).
• Total Nitrogen (TN): Annual aggregate load limits applicable to the James/Elizabeth River basin.
• Total Phosphorus (TP): Strict limitations to prevent eutrophication in the Bay.
• Bacteria: Enterococci limits for saltwater discharge.

B. Compliance History

The Army Base Treatment Plant maintains an exemplary compliance record. HRSD has received numerous NACWA (National Association of Clean Water Agencies) Peak Performance Awards for this facility, recognizing years of operation with zero permit violations. The plant plays a vital role in HRSD’s district-wide “bubble permit” strategy for nutrients, allowing the district to balance nutrient loads across multiple facilities to achieve net environmental benefits.

7. OPERATIONAL EXCELLENCE

A. Staffing & Certification

The plant is staffed by Virginia Class I Licensed Wastewater Operators. HRSD maintains a rigorous internal training program, widely regarded as one of the best in the industry, comprising apprenticeship programs and continuous education in biological process control and fluid mechanics.

B. Technology & Innovation

The facility utilizes a robust SCADA (Supervisory Control and Data Acquisition) system for real-time monitoring. HRSD is a leader in “Smart Utility” implementation, utilizing predictive analytics to optimize chemical dosing and aeration setpoints based on incoming flow and load modeling.

8. CHALLENGES & FUTURE PLANNING

A. Sea Level Rise & Subsidence

The most pressing technical challenge for the Army Base Treatment Plant is recurrent flooding. Norfolk is subject to land subsidence and rising sea levels, which threaten hydraulic grade lines and physical asset integrity. Future planning involves raising outfall weirs and potentially installing effluent pumping stations to discharge against higher high-tide conditions.

B. SWIFT (Sustainable Water Initiative for Tomorrow)

While the Army Base plant is not currently a primary SWIFT injection site, HRSD’s SWIFT program aims to treat wastewater to drinking water standards and recharge the Potomac Aquifer. In the long-term district master plan, flows from the Army Base service area may eventually be integrated into the SWIFT network to reduce surface discharges into the Elizabeth River effectively to zero.

9. COMMUNITY & REGIONAL IMPACT

The Army Base plant is an economic enabler for the region. By providing reliable wastewater treatment for Naval Station Norfolk, the facility supports national security operations and the thousands of jobs associated with the base. Environmentally, the plant’s rigorous nutrient removal has contributed directly to the recovering health of the Elizabeth River, evidenced by the return of oysters and varied fish species to the harbor.

10. TECHNICAL SPECIFICATIONS SUMMARY

11. FAQ SECTION

Technical Questions

1. What is the design capacity of the Army Base Treatment Plant?
The plant has a permitted design capacity of 18.0 MGD.

2. Does the facility perform on-site solids digestion?
No. Solids are typically thickened and pumped via force main to HRSD’s regional solids handling facilities (such as the Atlantic Plant) for digestion and processing.

3. Is the plant part of the SWIFT program?
Currently, the Army Base plant is not a direct SWIFT aquifer recharge site, but it is integrated into the HRSD system which is pivoting toward SWIFT implementation district-wide.

General Questions

4. Does this plant serve the Naval Base?
Yes, the Army Base Treatment Plant is the primary treatment facility for wastewater generated by Naval Station Norfolk.

5. How does the plant handle flooding?
The plant is undergoing active resiliency upgrades, including hardening of electrical infrastructure and flood-proofing buildings to withstand sea-level rise and storm surges.