Agenda - 06-02-2004-9d - Laserfiche WebLink

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~~~~~n~,-~ B~ MEMORANDUM TO: Ccunty Commissioners John Link, County Manager COPIES: Gwen Harvey, Assistant County Manager Rosie Summers, Health Director Pam Jones, Purchasing/Central Services Director Lori Taft, Recreations and Parks Director David Stancil, ERCD Director Mike Nicklaus, AIA, Innovative Design Barrett Kays, PhD, Landis, Inc, FROM: Ron Holdway, Environmental Health Director Tom Konsler, Environmental Health Supervisor Paul Thames, PE, County Engineer DATE: May 27, 2004 SUBJECT: County staff identified issues and recommendations related to proposed expansion of wastewater treatment system serving the County's Northern Human Services Center Background Qrange County's Northern Human Services Center (NHSC) has had a history of wastewater treatment system issues related to system regulatory compliance, operation and capacity. The system currently serving the facility - a relatively high capacity (2400 gallon per day [gpd]) pump conventional septic system -was completed and put into operation under near-emergency conditions (mandatory decommissioning of existing system) in early 1994, This system replaced an existing discharging sand filter system (discharging to the No, 1 sedimentation structure protecting Lake Qrange) that was non-complaint under the then (and still) current state wastewater treatment and watershed protection regulations, The pump-conventional septic system currently in use was designed by County Environmental Health and Engineering staff and permitted under local environmental health rules by the County Health Department, The system design was limited to a 2400 gpd capacity because, after extensive site evaluation of the entirety of the NHSC property by County Environmental Health Specialists and Soil Scientists, it was determined that a maximum of 2400 gpd could be accommodated in a contiguous nitrification field (a small non-contiguous nitrification field area was located west of the building and reserved as repair area), The new system was permitted with far less than the 100% nitrification field repair area typically required for such systems because the construction of the new system was regulated as an emergency repair, Soon after the new system became operational, system flow recording instrumentation indicated that it was being overloaded by wastewater flow often significantly in excess of system design rapacity. Comparison of wastewater flow and potable water flaw (from the on-site well) data indicated that there were several probable sources of excess flow: heavy though sporadic use of the building facilities during organized athletic/recreational events (basketball/softball league play); malfunctioning toilets and urinals; and infiltration of ground water during prolonged rainy