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

Browse Search

(1/24/03 through 4/24/03), far exceeding the proposed four-day flow equalization '~~ capacity; and • the consultant's projected 3000 gpd maximum average daily wastewater flow (based nn flow numbers generated by the maximum building use capacity) does not appear to address potentially significant flows associated with or generated by park use or potential development of park and ride facilities; and • significant components of existing peak flow appear to include leaking plumbing fixtures (toilets continuing to run after flushing), extended building use (athletic events) and ground water inflow/intrusion (during prolonged periods of wet weather). While providing water efficient fixtures will significantly reduce normal water use, it will probably not eliminate fixture malfunction, nor will it address the inflow problem, much of which occurs as groundwater leakage into and through the permeable joints of the aged and inaccessible wastewater lines (under building slab); and • use of the existing field places significant limits on future use or landscaping of facility's front lawn area; and • given the nature of and demand on the County's capital improvement program, it may be difficult to fund additional system expansion/improvement in the future. Step 3 does appear to be a viable option for an expanded capacity wastewater treatment system at the NHSC, in that it does provide a 6000 gpd treatment and subsurface disposal capacity. There is some question as to the need to provide the 4-day 12,000 gpd flow equalization component included in this alternative. It is the County staff opinion that a system providing a 6000 gpd treatment capacity will be sufficient to address average daily flaws of 3000 gpd as well as short-term (heavy facility use) and long-term (infiltration) peak flows without the use of a flow equalization component.. Staff recommends that the BOCC consider an alternative, designated as Step 3A, which is identical to the consultant's Step 3, in that it has a 6000 gpd capacity primary treatment (septic tanks), 6000 gpd secondary treatment (Living Machine) and 6000 gpd subsurface disposal (nitrification field located on the Vincent property), but does not have the proposed 12,000 gpd flow equalization component. The Step 3A alternative would provide the same level of actual treatment and environmental protection as the Step 3 alternative while achieving a level of construction cost savings (unknown at this time) realized by omitting the flow equalization component.. Preliminary discussion with state environmental health regulatory/permitting staff indicates that the operation of this system will probably require daily visits by a Grade II-certified wastewater treatment plant operator either having an additional subsurface disposal certification or working in conjunction with a second operator having a subsurface disposal certification„ If the state does ultimately determines such operating procedures are to be integrated into the system permitting requirements, the required expertise would have to be secured on a contract basis (within the Environmental Health staff there are individuals certified as subsurface operators but none certified or likely to be certified as Grade II operators). The minimum estimated annual out-of-pocket costs for a contract Grade II operator (with Environmental Health providing a coordinating subsurface operator) is $40,000. Comparison of Treatment System Technology Other than Living Machine Staff recognizes that the BOCC has expressed a preference to provide the NHSC with a wastewater treatment system that utilizes advanced or "cutting edge" technology such as that provided by the proposed Living Machine technology secondary treatment component.