Agenda - 06-06-2000-10 - Laserfiche WebLink

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The Town of Hillsborough's existing wastewater treatment plant has a permitted capacity of 3.0 million gallons per day (mgd). The average daily wastewater flow to that plant is currently 0.9 mgd, but peak flows in excess of 2.0 mgd have been experienced. Peak flows at the sewer plant do not necessarily track with peak water consumption days. Peak sewer flaws are generally a consequence of high storm and ground water infiltratian/inflow events such as intense rainstorms and prolonged periods of wet weather. On average, the Town currently produces 0.7 mgd more treated water than is returned as wastewater. Much of this difference can be explained as losses within the water distribution system but some of the difference is due to the fact that the Town has a number of water customers that are not sewer customers. Looking at the Town's water use projections and assuming a consumptive loss (from such activities as evaporation during washing/drying clothes, cooking, watering lawns and the like) often percent, it is probable that the Town's total additional wastewater treatment demand will approach 1.1 mgd. By 2010, the Town's total average daily wastewater flow and demand should be around 2.0 mgd with peak flows topping out in excess of the Town's current 3.0 mgd wastewater treatment capacity. In addition to expanding its water supply and treatment capacity, the Town will be forced to expand its wastewater treatment capacity. It will also have to improve the wastewater treatment plant's nitrogen removal efficiency to comply with the recently adopted Neuse River Basin rules. II. Efland Sewer S stem Ca aei The existing "Wastewater Collection and Purchase Contract" between Orange County and the Town of Hillsborough calls for the Town to allocate 380,000 gpd of its wastewater treatment capacity to the Efland sewer system. Furthermore, the contract calls for the Town to notify the County when the Town's remaining treatment capacity is less than 500,000 gpd if the County's 380,000 gpd allocation has not been fully utilized. The Town is also required to provide the County with notice of the timetable necessary for it to provide the County with wastewater treatment service for the unused portion of the reserved wastewater treatment capacity. Under average daily flow conditions, the Town's current wastewater treatment capacity is sufficient to treat the its own projected wastewater flow as well as provide for the County's 380,000 gpd wastewater flow through the year 2010. However, it is likely that the Town will have to either expand its treatment capacity or reduce storm and ground water inflow/infiltration capacity to meet its own peak daily flows, regardless of any increase in flow from the Efland system, at some time prior to 2010. The average daily wastewater flow from the Efland system currently approaches 30,000 gpd, leaving an excess capacity (from a contractual standpoint) of approximately 350,000 gpd. The existing infrastructure of the Efland system is capable of collecting and pumping well in excess of the 380,000 gpd contractual wastewater treatment capacity. The key concern related to capacity demands of the Efland system is timing: the relationship between the timing of the Efland system's increasing demand for wastewater treatment and the timing of Hillsborough's increasing demand and wastewater treatment plant expansion. This timing will ultimately be a key criteria, perhaps the key criteria, in the process of approving the extension of wastewater collection services to a development or other type of wastewater customer in Efland.