Beaufort Jasper Water And Sewer Authority Cherry Point Wastewater Treatment Plant

FACILITY BASIC INFORMATION

Plant Name: Cherry Point Water Reclamation Facility

Location: Okatie, Beaufort County, South Carolina

Operating Authority: Beaufort-Jasper Water & Sewer Authority (BJWSA)

Design Capacity: 7.5 MGD (Expanded)

Current Average Flow: ~3.5 – 4.5 MGD

Population Served: ~40,000+ residents (est.)

Service Area: Okatie, Sun City Hilton Head, Bluffton, Pritchardville

Receiving Water Body: Great Swamp (Tributary to New River) & Public Reuse Irrigation

NPDES Permit Number: SC0045781

Read more4D-Printed Smart Materials For Water Treatment

Year Commissioned: 1997 (Major expansions in 2004, 2021)

1. INTRODUCTION

The Cherry Point Water Reclamation Facility (CPWRF) serves as a cornerstone of wastewater infrastructure for the rapidly developing Southern Beaufort County region. Operated by the Beaufort-Jasper Water & Sewer Authority (BJWSA), this advanced secondary treatment facility is critical to maintaining the ecological balance of the sensitive Lowcountry estuarine environment while supporting high-density residential developments, including Sun City Hilton Head.

Recently expanded to a rated capacity of 7.5 million gallons per day (MGD), the facility is distinguished by its aggressive approach to water reuse. It functions as a zero-discharge facility during dry weather, diverting highly treated effluent for irrigation use on local golf courses and residential common areas. The plant is also notable for its sustainable biosolids management, utilizing passive solar drying technology to reduce waste volume. As BJWSA’s strategic hub in the Okatie area, Cherry Point exemplifies the integration of capacity growth with environmental stewardship in a coastal zone.

2. FACILITY OVERVIEW

A. Service Area & Coverage

The CPWRF service area encompasses the high-growth corridor of Okatie and Bluffton in Beaufort County. The primary contributors to the collection system are the large-scale planned communities of Sun City Hilton Head and Riverbend, as well as commercial developments along the Highway 170 and Highway 278 corridors. The collection system relies on a network of lift stations designed to navigate the flat coastal topography, conveying flow to the centralized headworks at Cherry Point.

B. Operational Capacity

Following the Phase 3 expansion completed circa 2021, the facility’s design capacity increased from 5.0 MGD to 7.5 MGD. The plant is designed to handle significant diurnal peaks associated with the residential nature of its service base. Current average daily flows hover between 3.5 and 4.5 MGD, providing a safe operational buffer for near-term regional growth. Long-term planning by BJWSA anticipates potential future expansions to 11.25 MGD to accommodate projected population influxes in the Jasper and Beaufort county border regions.

C. Discharge & Compliance

The facility operates under a stringent NPDES permit regulating discharge into the Great Swamp, a tributary of the New River. The receiving waters are classified as Freshwaters (FW), requiring high-level removal of Biochemical Oxygen Demand (BOD), Ammonia-Nitrogen, and Suspended Solids to prevent eutrophication. Uniquely, the plant prioritizes water reclamation; a significant percentage of effluent is treated to reuse standards and distributed via a “purple pipe” system for irrigation, reducing potable water demand and limiting discharge into the Great Swamp.

3. TREATMENT PROCESS

The Cherry Point WRF utilizes an oxidation ditch configuration with Biological Nutrient Removal (BNR) capabilities, followed by tertiary filtration and UV disinfection to meet reuse standards.

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A. PRELIMINARY TREATMENT

Raw wastewater enters the headworks where it undergoes physical screening and grit removal.

• Screening: Mechanical fine screens remove plastics, rags, and large debris to protect downstream pumps and aeration equipment. Screenings are washed, compacted, and disposed of off-site.
• Grit Removal: A vortex grit removal system separates heavy inorganic solids (sand, coffee grounds) from the organic waste stream to prevent accumulation in the oxidation ditches.
• Odor Control: The headworks are enclosed and vented to a chemical or biological scrubber system to mitigate odors, a critical requirement given the facility’s proximity to residential zones.

B. SECONDARY TREATMENT

The biological treatment core consists of oxidation ditches. This extended aeration process provides a large hydraulic retention time, allowing for robust breakdown of organics and nitrification.

• Configuration: The plant utilizes multiple oxidation ditch trains (rotors/brushes or jet aeration) to circulate mixed liquor.
• Biological Nutrient Removal (BNR): The process is tuned for nitrification (ammonia conversion to nitrate) and denitrification. Anoxic zones are created within the ditch or in selector basins to facilitate the reduction of total nitrogen, essential for protecting the New River watershed.
• Clarification: Mixed liquor flows to secondary clarifiers (circular center-feed units) where biological floc settles. The clear supernatant overflows the weirs, while Return Activated Sludge (RAS) is pumped back to the ditches.

C. TERTIARY TREATMENT & FILTRATION

To meet “Public Access” reuse standards, the secondary effluent undergoes tertiary filtration.

• Filtration Technology: The facility utilizes deep bed sand filters or cloth media disk filters to remove remaining suspended solids, reducing turbidity to levels acceptable for unrestricted irrigation.
• Target Performance: Turbidity is consistently maintained below 2 NTU to ensure the efficacy of the downstream UV disinfection.

D. DISINFECTION

The facility utilizes Ultraviolet (UV) Disinfection rather than chlorination.

• Method: Flow passes through banks of UV lamps submerged in channels. The UV light scrambles the DNA of bacteria and viruses, rendering them unable to reproduce.
• Benefits: This method eliminates the formation of carcinogenic disinfection byproducts (DBPs) such as trihalomethanes, which is preferable for water sprayed on golf courses and residential lawns.

E. SOLIDS HANDLING

BJWSA employs a sustainable approach to solids management at Cherry Point.

• Digestion: Waste Activated Sludge (WAS) is stabilized via aerobic digestion, reducing volatile solids and vector attraction.
• Dewatering: Digested sludge is thickened and dewatered, typically using belt filter presses or screw presses.
• Solar Drying: The dewatered cake is processed in passive solar drying greenhouses. Automated “moles” or tillers churn the sludge, allowing solar heat to dry the material to a high-solids content (Class A or near Class A equivalent). This significantly reduces the volume and weight of material requiring landfill disposal or land application.

4. INFRASTRUCTURE & FACILITIES

A. Physical Plant

The site is characterized by its modern layout, designed to blend with the surrounding Lowcountry landscape. The most distinct architectural features are the large, translucent greenhouse structures used for biosolids drying. The site includes a dedicated administration building, SCADA control room, and fully equipped laboratory for compliance testing.

B. Energy Efficiency

BJWSA has integrated energy efficiency into the plant’s design. The oxidation ditches utilize Variable Frequency Drives (VFDs) on rotors and pumps to match energy consumption with biological demand. The solar drying operation represents a significant energy offset, utilizing passive solar energy to remove water from biosolids rather than gas-fired thermal drying.

C. Odor Control

Odor control is a Tier-1 operational priority. The facility utilizes covered headworks and biofiltration units. Air from the primary odor-generating sources is forced through organic media beds where naturally occurring bacteria oxidize odorous compounds (H2S) into non-odorous byproducts.

5. RECENT UPGRADES & MAJOR PROJECTS

Cherry Point Capacity Expansion Phase 3 (2019-2021)

Great Swamp Effluent Management System

While not strictly “in-plant,” BJWSA has invested heavily in the wetlands dispersion system. This project ensures that during wet weather periods when irrigation demand is low, the effluent released into the Great Swamp mimics natural sheet flow, enhancing nutrient uptake by the wetland ecosystem before the water reaches the New River.

6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

The Cherry Point WRF operates under strict regulatory oversight by the South Carolina Department of Environmental Services (SCDES / formerly DHEC).

• Permit Type: NPDES & Land Application (ND) Permit.
• Reuse Standards: The facility meets standards for “Unrestricted Urban Reuse,” allowing the water to be used on public access areas like golf courses and parks.
• Nutrient Limits: Strict limits on Total Nitrogen (TN) and Total Phosphorus (TP) are enforced to protect the Port Royal Sound watershed, which is designated as Outstanding Resource Waters (ORW) in many areas.
• Compliance Record: The facility maintains a high compliance record, frequently earning the “Peak Performance Award” from the National Association of Clean Water Agencies (NACWA).

7. OPERATIONAL EXCELLENCE

Staffing: The plant is staffed by state-certified biological wastewater operators. BJWSA maintains a strong internal training program, requiring operators to hold or pursue “A” level South Carolina Biological Wastewater Physical/Chemical certifications.

Automation: The facility is monitored 24/7 via a centralized SCADA system. This allows for real-time adjustment of Dissolved Oxygen (DO) levels in the oxidation ditches and automated flow pacing for chemical feed and UV intensity.

8. CHALLENGES & FUTURE PLANNING

Current Challenges

• Growth Management: The Okatie/Bluffton corridor is one of the fastest-growing areas in the state. Keeping infrastructure construction ahead of developer demand is a constant logistical and financial challenge.
• Wet Weather Management: While the reuse system is efficient, extended periods of rain reduce irrigation demand, forcing the plant to discharge to the Great Swamp. Managing hydraulic peaks during hurricane season is a critical resilience concern.

Future Planning

BJWSA’s Capital Improvement Plan (CIP) identifies the potential need for a future expansion to 11.25 MGD. This “Phase 4” expansion would likely involve the addition of parallel treatment trains and potentially membrane technologies (MBR) if regulatory limits on nutrients tighten further. The Authority is also exploring aquifer storage and recovery (ASR) to store reclaimed water during wet months for use during dry months.

9. TECHNICAL SPECIFICATIONS SUMMARY

10. FAQ SECTION

Technical Questions

1. Does Cherry Point WWTP use membranes for treatment?
Currently, the plant relies on oxidation ditches and tertiary media filtration. While Membrane Bioreactor (MBR) technology is used at other BJWSA facilities (like the Purrysburg WTP), Cherry Point utilizes conventional advanced treatment. Future expansions may consider membranes.

2. What is the hydraulic retention time (HRT) of the oxidation ditches?
While specific operational variables fluctuate, oxidation ditches in this configuration typically operate with an HRT of 18-24 hours to ensure complete nitrification and sludge stabilization.

3. How does the solar drying system work?
Dewatered sludge is spread in a thin layer inside a greenhouse. An automated “mole” travels through the sludge, turning it over to expose wet surfaces. Solar heat evaporates the moisture, reducing the sludge volume by up to 75%.

Public Interest Questions

4. Is the reclaimed water safe for lawns?
Yes. The “purple pipe” water meets strict DHEC standards for public contact. While it is not potable (drinking) water, it is highly treated and disinfected, making it safe for irrigation.

5. What causes odors near the plant?
Occasional odors can occur during upset conditions or solids processing. However, the plant utilizes chemical scrubbers and biofilters to scrub air before it is released. Residents can report odors directly to BJWSA.

6. Does the plant discharge into the river?
The plant primarily seeks to reuse water for irrigation. When demand is low (winter or rainy days), highly treated effluent is released into the Great Swamp, which acts as a natural buffer before water reaches the New River.