At R.O. Anderson, our Water and Wastewater Infrastructure group has the capabilities to design and permit infrastructure related projects which range from simple extensions of storm, sewer, and water mains to complete design, analysis, environmental clearance, and permitting of complex sewer, water, and storm drainage systems.
The Eastern Sierra Community Services District needed to determine economical options to increase the treatment and disposal capacity to accommodate the projected growth at the Bishop Paiute Tribe. Early in the process it was determined that elevated levels of nitrogen were present in the groundwater monitoring wells downgradient of the existing evaporation/percolation ponds and effluent irrigation areas. Therefore, in addition to treatment and disposal of additional flow, the study also addressed nitrogen removal from existing flows to lessen the degradation of the groundwater.
We completed the preliminary design for a number of different treatment and irrigation options. Options were evaluated in several areas including: cost; reliability; performance; and preliminary environmental factors and the findings were presented to ESCSD.
Nitrogen may be removed in the treatment process or through careful and proper irrigation, or a combination of both methods. Through discussions with staff at the Lahontan Regional Water Quality Control Board (LRWQCB) concerning this project, it was determined that they will be enforcing antidegradation water quality standards in the Owens Valley whereby the proposed new discharge must not degrade groundwater from the existing background levels of 1 to 2 mg/L total nitrogen. Historically, LRWQCB has only enforced the beneficial use standards (less than 10 mg/L total nitrogen) and not the more stringent antidegradation standards. In order to allow total nitrogen above the existing quality the LRWQCB must make findings to support allowing the higher levels. The findings that are expected to be pursued to support limited degradation of the groundwater include: technical feasibility; cost; and public benefit.