Agenda - 06-29-2000-9f - Laserfiche WebLink

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36 .; MEMORANDUM TO: Robert Davis - FROM: Paul Thames, PE, County Engineer COPIES: John Link, County Manager Geof Gledhill, Caunty Attorney DA'T'E: May 1, 2000 SUBJECT: Richmond Hi11s sewer system layout This memorandum represents my formal comment to the Planning Department relative to the proposed sewer collection system and its connection to the existing Efland sewer system for Habitat for Humanity's Richmond Hills subdivision. It is clear that the development of the Richmond Hills subdivision, at least to the extent of obtaining more than 401ots from the acreage owned by Habitat for Humanity, requires that wastewater be pumped from Richmond Hills into the portion of existing gravity wastewater collection system that passes nearby. It is also clear, from the viewpoint of an engineering and sewer utility professional, that the integration of centralized wastewater pumping stations into a wastewater collection system is not a desirable alternative and thus avoided whenever possible. Pumping stations are avoided because, even in the best light, they are a nuisance. Pumping stations are a source of odors; they require constant preventive maintenance (twice a week or more); equipment failures tend to be time consuming, complicated and expensive to repair; and sewerage spills at pumping stations represent the overwhelming majority of all system spill incidents. As the NC Divisiorl of Water Quality (DWQ) has recently adopted a policy of zero tolerance for sewerage spills, pumping stations also represent a serious exposure to substantial environment fines and adverse publicity. The disadvantages cited above are particularly manifest when considering the use. of pumping stations in the Efland sewer system. The added disadvantages applicable specifically to the Efland sewer system are a consequence of the absence of a County utility department with the ability to respond quickly to pumping stations problems. Maintenance of the system's one existing pumping station is currently provided under a contractual arrangement by Orange Water and Sewer Authority (OWASA). For nearly twelve years, OWASA has provided perfectly adequate service and response for the Efland wastewater pumping station. However, OWASA's ability to respond quickly in an emergency is limited by a number of factors: 1) OWASA's operating staff are located in Chapel Hill and have a response time that would fall between 30 minutes and one hour under optimum conditions; 2) it is unlikely that area residents who might be involved in reporting amalt-unction at a pumping station would know to call OWASA directly; and 3) in the event of an area•wide emergency such as a hurricane, OWASA maintenance staff may not be able to get through to Efland and, in any event, would probably be fully occupied in dealing with OWASA's own infrastructure.