4.0 Population, Water Demand,
and Wastewater Flow Projections
In determining the feasible alternatives for the regionalization of water and wastewater service in Bamberg County, it is necessary that population, water usage projections, and wastewater flow projections be calculated to provide a basis for sizing and locating the optimal regionalization components.
The five (5) entities in Bamberg County that provide public water service have graciously provided information and/or SCDHEC records on current water usage and wastewater flows. The water usage and wastewater flows for each of these entities, along with projected population growth and due consideration for industrial development potential, provide a foundation for determining the projected future water usage and wastewater flows for Bamberg County.
4.1 Population Data
and Population Projections
The State of South Carolina Office of Research and Statistics (SCORS) provided the base population data and population projections. Demographic and population data determined by the 2000 Census, included in Appendix M, was provided for the entire planning area and for selected entities within the planning area. Population for the various service areas was approximated based on census block data.
The population projections for each identified municipality were calculated based on the projected percentage of change for the entire County as determined by SCORS. SCORS has prepared population estimates for Bamberg County in five (5) year increments through the year 2030 using the year 2000 actual census data as a baseline. Unfortunately, SCORS projects a decrease in the residential population within Bamberg County over the next twenty (20) years. The existing and projected service area populations are included in Table 4.1-1.
Table 4.1-1-Existing Population
and Population Projections for Existing Water Service Areas
Note: Above estimates are based on total municipal populations instead of existing water or wastewater customer base.
Additionally, it should be noted that the population of Bamberg County has been slowly decreasing since the early 1900’s. Notwithstanding these declining population trends, the leaders of Bamberg County are making efforts to reverse these trends as evidenced by their proactive industrial recruiting efforts and the commissioning of this study.
4.2 Projected Areas
of Industrial Development
There are several existing industrial parks and industrial sites in Bamberg County. Potential water demands and wastewater flows from these areas must be considered for the long term planning of water and wastewater system regionalization. The Bamberg County Airport Industrial Park, located along U.S. Highway 78, is supplied with water service by the City of Denmark Department of Waterworks. The Cross Rhodes Industrial Park, located along U.S. Highway 301, is supplied with water and wastewater service by the BBPW. There are also several vacant industrial buildings in Bamberg County, including the Holland Atlantic Hitch Facility in Denmark and the NIBCO Facility in Denmark. Both facilities are provided with water and wastewater services by the City of Denmark Department of Waterworks.
It is also important to note that approximately eighty percent (80%) of the population within Bamberg County resides north of the Little Salkehatchie River. A population density map of Bamberg County, depicted in Exhibit AA, clearly demonstrates this. The majority of future economic and industrial development within the County is expected to occur near the water and wastewater service areas of the City of Denmark and/or the BBPW. The corridor between the City of Bamberg and the City of Denmark would appear to be quite suitable for industrial and economic development due to its geographic location between these cities, the availability of water service, and the proximity to the airport.
4.3 Water Demand Projections
In order to evaluate future supply, storage, and distribution capacities, it is important to project total water usage based on the anticipated population to be served. System evaluations allow analysis of the current and projected usage with respect to their capacities in order to address existing and potential problems which may create maintenance issues or to meet SCDHEC requirements. The number of water customers was projected based on the municipal populations projected by SCORS, which can be found in Table 4.1-1. This growth rate is coupled with a one percent (1%) annual increase in customers due to system expansions and economic development. The one percent (1%) annual increase is believed to be a modest and nominal assumption for the expansion of service and economic development. Additionally, the potential regionalization of the water system may provide water services to more residents of Bamberg County which further supports the assumption of a modest one percent (1%) annual increase in customers. The total customers of each municipal water system are then projected in Table 4.3-1.
Table 4.3-1 Water Customer Projections
With these relatively modest projections, a net increase of about 812 customers is expected from 2006 to 2030 for the areas within and around the existing public water systems in Bamberg County. A disaggregation of the designations and types of customers based on information obtained from the water purveyors and the SCDHEC is presented in Table 4.3-2.
Table 4.3-2 Disaggregated Water Customer Projections
For conceptual planning and projection of anticipated supply needs, it is assumed that each resident will consume 100 gallons per day. The assumption of 100 gallons of water usage per resident per day, found in the Ten State Standards for Water Works Design, is widely accepted for new water systems. According to the 2000 Census, the average household within Bamberg County consisted of approximately 2.5 persons. For purposes of water and wastewater studies, the term Equivalent Residential Unit (ERU) can be defined as an entity for which the average water consumption or wastewater generated by customer that is equivalent to the average water consumption or wastewater generated by a single-family home. For purposes of this study, an ERU in Bamberg is presumed to have an average water usage of 250 GPD. After deducting the usage associated with the residential customers, non-residential ERU’s will be determined by the average daily water usage calculations based on system usage divided by 250 GPD. The non-residential average daily water usage calculation, total projected water usage, and total ERU’s related to both residential and non-residential usage per municipal system is presented in Table 4.3-3.
Table 4.3-3 Non-Residential Average Daily Water Usage and ERU’s
Note: 400,000 GPD to the City of Denmark via a master meter not included in BBPW usage.
The total ERU calculations allow the associated water usage of each system to be expressed in terms of a typical demand associated with residential usage. The ERU’s for each municipal system were projected with a one percent (1%) annual increase in a manner similar to customer projections. Table 4.3-4 estimates the anticipated water usage for each municipality and the potential regional system based on the projected growth of total usage by 2030.
Table 4.3-4 Anticipated Water Usage
Note: 400,000 GPD to the City of Denmark via a master meter not included in BBPW usage or capacity.
It is important to note that Table 4.3-4 does not include elevated storage requirements to achieve minimal fire flow protection. Additionally, the projected municipal water usage does not include potential new customers that may be provided with domestic water service due to extension of new water mains for interconnecting existing water systems. It is anticipated that the City of Denmark will reach its existing supply capacity prior to the year 2010. Due to the regional interconnection between the City of Denmark and the BBPW, however, all of the City of Denmark’s water needs can be supplied by the BBPW. The BBPW has an anticipated surplus in 2010 and is quite capable of supplying additional water to the City of Denmark. All of these existing public water systems in Bamberg County, except for the City of Denmark, are anticipated to have a surplus of water supply capacity. It is important to recognize again that approximately seventy-five percent (75%) of the existing groundwater supply capacity within Bamberg County is owned, operated, and maintained by the BBPW. Any regional water system must include the BBPW to foster economic development within the region.
4.4 Wastewater Generation Projections
Projections of the future anticipated wastewater flows were based on water usage, historical rates of wastewater generation from certain key customers, and historical rates of flow at the active WWTP’s. For purposes of this study, water usage is assumed to be equivalent to wastewater generation. This being the case, the wastewater flow generated by each residential customer is assumed to be 250 GPD. Customer data was compiled from each of three (3) public wastewater service purveyors and records maintained by the SCDHEC. Additionally, a modest and nominal projection of one percent (1%) annual increase was assumed for the expansion of service and economic and industrial development within the existing service areas. Wastewater customer projections are tabulated in Table 4.4-1.
Table 4.4-1 Wastewater Customer Projections
The BBPW and the City of Denmark provided wastewater service to approximately seventy-eight percent (78%) and ninety-seven (97%) of their water customers in 2006, respectively. A disaggregation of wastewater customers by their designation, based on information obtained from the three (3) wastewater purveyors and SCDHEC’s historical records, is tabulated in Table 4.4-2. The City of Denmark provides wastewater service to more residential customers than the BBPW, even though the City of Bamberg has a larger population than the City of Denmark.
Table 4.4-2 Disaggregated Wastewater Customer Projections
Assuming that a typical residence in Bamberg County contains an average of 2.5 persons per household, as indicated by the 2000 Census, approximately 6,917 persons in Bamberg County are supplied with wastewater service. SCORS estimates the current population of Bamberg County to be approximately 15,810. Accordingly, approximately fifty-six percent (56%) of Bamberg County residents are not currently provided with wastewater service. For purposes of this study, it is assumed that the average wastewater flows from the non-residential customers are equal to non-residential average daily water demand as indicated in Table 4.3-3 of the anticipated water usage projections. The total number of wastewater ERU’s per public wastewater service purveyor is tabulated in Table 4.4-3.
Table 4.4-3 Wastewater ERU’s
The total number of ERU’s for these three (3) public wastewater service purveyors is estimated based on 250 GPD per ERU being discharged to the wastewater system. The anticipated wastewater flows for each wastewater service purveyor are projected in Table 4.4-4, assuming an annual one percent (1%) increase in wastewater flows due to growth within the existing service area.
Table 4.4-4 Anticipated Wastewater Flows
Based on the projected increases in wastewater flows, both the BBPW and the Town of Ehrhardt would be expected to need expansions of their treatment capacity over the evaluated time period. Current flows at the WWTP’s considered in conjunction with the current numbers of customers would not support these projected needs for expansion, but as the standards of living are raised (as is hoped with increased economic and industrial development), the per capita water usage is expected to rise closer to the assumed value of 250 GPD per capita. It should also be noted that if wastewater service were regionalized between the three (3) existing wastewater service purveyors, there would be a combined treatment capacity of approximately 2.115 MGD, thereby resulting in a surplus of treatment capacity.