Site work for a water / sewer project in Summerville, South Carolina. Completed plans call for site work for a water / sewer project.

As of April 26, 2023, project has been under construction since last month, and is expected to be completed in 3 years. The owner has determined a prequalified list of construction managers. Dorchester County owns and operates the Lower Dorchester Wastewater Treatment Plant (WWTP). The County has a National Pollutant Discharge Elimination System (NPDES) permit for an annual average design flow of 8 million gallon per day (mgd) with permit limits for expansion to 10 and 12 mgd. The WWTP is located 0.78 mile from the confluence with the Ashley River near the Charleston County line. The Lower Dorchester WWTP serves approximately 44,000 people. The majority of the influent flow is pumped to the WWTP. Dorchester County wishes to expand the Lower Dorchester WWTP to accommodate growth in the service area. The projected wastewater flow in the Lower Dorchester service area is anticipated to exceed the Lower Dorchester WWTP permitted capacity of 8 mgd over the next 20-year planning period. The County has currently committed 9 mgd of capacity at the Lower Dorchester WWTP. Additionally, the County has received firm requests for an additional 4.5 mgd of capacity, which is commensurate with the anticipated growth per the County's Comprehensive Plan. It is anticipated that the majority of the growth in the Lower Dorchester service area will occur within the next 5 to 10 years. Therefore, an expansion of the Lower Dorchester WWTP from 8 to 16 mgd is necessary to prepare for the anticipated near-term growth. The County is also anticipating growth in an area north of the Lower Dorchester service area, characterized as the Central Dorchester service area, within the next 5 to 15 years. An initial capacity of 4 mgd has been identified for a proposed Central WWTP with a future expansion to 8 mgd. The Preliminary Engineering Report (PER) for the proposed Central WWTP is being prepared as a separate document from this Basis of Design Report (BODR) for the Lower Dorchester WWTP expansion project. The proposed Central WWTP is discussed in this BODR due to the re-distribution of the County's ultimate oxygen demand (UOD) wasteload allocation between the two treatment facilities.