The Sierra Foothill Charter School (SFCS), previously known as the Cathey’s Valley Elementary School, operates a water system with one active well. The single well solely serves the school property and is located at the southeast portion of the school site. The existing well contains a concrete slab and supporting infrastructure of three water tanks and a pumphouse. In June 2016, the single active well for the SFCS was taken offline after a sample for nitrate-N levels taken exceeded the Maximum Contaminant Level (MCL) of 7-10 mg/L nitrate-N regulated by the State Water Resources Control Board, Division of Drinking Water (DDW). The data for the nitrate-N levels were plotted with precipitation and results showed that nitrate spikes follow seasonal precipitation, which indicates nitrate is transported to the well following seasonal recharge. Based on this pattern, it is likely nitrate-N levels sampled in the well may have reduced to an acceptable quality, but the Mariposa County Unified School District would like a second well installed and constructed to avoid any future issues. The original well will remain in use for irrigation purposes.
The proposed new well will be located on the SFCS school site (APN: 016-280-005-000), but at a different location from the existing well (400 feet apart). The proposed well will be drilled to an estimated 700 feet below ground surface (bgs) or less depending on the geology. Associated chlorination treatment and hydropneumatics pressure systems and other appurtenances necessary for the production and treatment of domestic water will be installed. The Project will also add two new 2,500-gallon water storage tanks, a pump house to house the booster pumps, and six (6) inch diameter pipeline connection of approximately 100 feet to the existing distribution system. Pipeline excavation will be limited to 3.5 feet deep or less.
Operations and maintenance of the proposed Project would be consistent with that of the existing well. Due to the exceedances of water quality standards, water is currently delivered in 3,000 gallon increments every two (2) weeks by truck and then utilized from an on-site storage tank.