Crane Flat Yosemite Institute Campus Septic System Repair
• System #1 serves a trailer with a single occupant. The current septic tank is substandard; it allows snowmelt infiltration during the spring which results in an overflow of effluent to the surface. This project proposes a lift station from system #1 to system #3 (the bathhouse system) in order to eliminate the substandard tank.
• System #2 serves the campus kitchen. The drain field on this system is required to be closed during periods of high water as measured on system #3. This project proposes two repairs to this system:
a) Installation of a 2" piezometer to the level of 15' below grade. This will allow independent monitoring and operation of this system during times of high groundwater.
b) Installation of a lift station to the treatment tanks on system #3. This will allow for greater access for pump trucks during the winter, when high groundwater occasionally requires pumping instead of discharging to the drain field.
• System #3 serves the bathhouse. This project proposes the following changes to system #3.
a) Piezometer #5 is the main monitoring piezometer for this system, and is located to a depth of 9' below grade. The proposal is to extend this piezometer to a depth of 15' below grade in order to monitor groundwater levels before they reach the 9' depth and the system must be closed down.
b) Yosemite Institute and NPS Facilities Management are investigating drain field replacement options for system #3, to alleviate issues associated with high groundwater. In order to gather information required for locating the best site, a new 2" piezometer would be located on the hillside west of campus (see map) to a depth of 15'.
c) Upon analysis of the piezometer data gathered throughout the winter/spring, YI will work with NPS, the California Regional Water Quality Control Board, and an engineer to develop a plan for a replacement drain field in an appropriate location. Exact details of this plan will be submitted to NPS for final approval.
This project proposes the following repairs to the three septic systems located at Yosemite Institute's Crane Flat campus.