The Dorchester County Water & Sewer Department serves 35,000 sanitary sewer customers. The Charleston Water System bills 4,300 customers for the department. The current sewer service area covers approximately 556 square miles.
The department owns and operates two wastewater treatment facilities: the Upper Wastewater Treatment Plant in Saint George and the Lower Wastewater Treatment Plant in North Charleston. It is comprised of 165 pump stations, approximately 150 miles of force main, approximately 13,500 manholes, and approximately 565 miles of gravity sewer line. 
There are two other sewer providers in the county.  They are the Town of Harleyville and Summerville Commissioners of Public Works (CPW). 

Upper Wastewater Treatment Plant

The Upper Wastewater Treatment Plant (WWTP) is an 1.8 MGD activated sludge wastewater treatment plant which handles flows from St. George and other surrounding communities.  The Upper WWTP has a reclaim water distribution line which can be activated with the installation of a Reclaimed Water Storage Tank and high head service pumps. Plant effluent is disinfected with chlorine and dechlorinated using sulfur dioxide before discharged into Polk Swamp.  The sludge generated from the activated sludge process is dewatered using two screw presses.  The dewatered sludge is disposed at a sanitary landfill.  

Lower Wastewater Treatment Plant

The Lower WWTP is an 8 million gallons per day (MGD) activated sludge plant which is currently undergoing an expansion to 16 MGD. A more detailed description of the expansion is found under Wastewater Plant Upgrade.  The Lower WWTP handles flows from Ridgeville, Givhans, and Wescott Areas of the County.  The WWTP disinfects the wastewater effluent using UV disinfection before discharging into Coosaw Creek.  This WWTP is designed to produce reclaimed water which is sold to local industries.  The generated sludge from the activated sludge process is dewatered using centrifuges before disposal in a sanitary landfill.

Wastewater Plant Upgrade

The Lower WWTP is expanding from 8 million gallons per day (MGD) capacity to 16 MGD capacity to handle projected increased flows from residential and industrial development.  This project includes partial demolition of the existing Lower Dorchester WWTP, construction of two new clarifiers and two new aeration basins, rehabilitation of two existing aeration basins, new solids handling facilities, a new preliminary treatment facility, construction of new disinfection facilities and construction of maintenance facilities.  Once completed, the expanded Lower Dorchester WWTP will provide the necessary capacity to accommodate projected growth to 2050. 

The Project has been broken into three phases. The following is a description of each phase:

Phase 1                                                                                                              Phase 1 of the Project will expand the capacity of the Lower Dorchester WWTP from 8 MGD to 10 MGD and demolish several structures in preparation for further expansion.  Structures to be demolished include:

• Abandoned aeration basins 1 & 2
• Abandoned UV disinfection system
• Existing Sludge Digesters 1 & 2
• Existing Sludge Dewatering Beds
• Abandoned RAS Pump Stations 1 & 2
• Existing Maintenance Building
• Existing Clarifiers 3 & 4

Also included in Phase 1 are:

• Installation of a new electrical feed to accommodate the increased power requirements for the expansion.
• Installation of aeration diffusers to expand the capacity of the Lower Dorchester WWTP from 8 MGD to 10 MGD
• Installation of blowers to provide air to the newly installed aeration diffusers
• Installation of emergency generator to power aeration blowers during power failure
• Purchase of two long lead time pieces of electrical equipment – Main Panelboard and Generator

Phase 2

Phase 2 of the project includes construction of structural components for Aeration Basins 1 & 2 and prepurchase of major process equipment. 

Phase 3

Phase 3 of the project includes:

• Installation of aeration equipment for the new Aeration Basins
• Construction of the Maintenance Building
• Construction of Preliminary Treatment Facility
• Construction of UV disinfection system
• Construction of Tertiary Filter Complex
• Construction of Sludge Thickening Building
• Construction of Sludge Holding Building
• Construction of two new Clarifiers
• Construction of Jockey Influent Pump Station
• Construction of Electrical and Blower Building

The total cost of the WWTP is $201 million.

Wastewater Master Plan Update

The Original Wastewater Master Plan was updated to reflect the current status of projects under development.  In this update, project with current development proposals or plans were prioritized  Any projects without development plans were reassigned to a later timeframe.  Due to a reduction in flow requirements for the Ridgeville Industrial Park, additional wastewater capacity was allocated for use by other developments.  This Master Plan update, reflects these changes.