Presented by thomas j. Haglund, general manager UNITENDED CONSEQUENCES OF THE MOST EPIC DROUGHT IN RECORDED HISTORY? Impacts to wastewater systems Presented by thomas j. Haglund, general manager Tuolumne utilities district, sonora February 8, 2018

Overview of TUD’s sonora regional wastewater treatment facility The District utilizes approximately 140 miles of pipeline to collect between 400-500 million gallons of sewage per year (based on average precipitation).

Sewer Connections – 6,174 direct, 8,955 total (THCSD and JSD) A look at the numbers Sewer Connections – 6,174 direct, 8,955 total (THCSD and JSD) The original facility was constructed in the late 1970’s Operates 29 Sewer Lift Stations Maintains 140 miles of sanitary sewer collection system Operates two Wastewater Treatment Plants Maintains 10 miles of Recycled Water Pipeline 100% of the wastewater is recycled

Drought related unintended consequences to tud wastewater collection system 29 sewer lift stations in mountainous terrain experienced increased maintenance Due to lower flows Geography of area created difficult flow scenarios Increase in solids settling in pipes; increase in blockages Significant increase in flushing operations to promote flow in collection system More fats, oils and grease issues Increase in lateral pipeline work orders Increase in odors Increase in root intrusion

Lack of water in the system impacts wastewater treatment Comparison: the peak flow at the regional plant experienced a 35% reduction as a result of extreme conservation measures Treatment Process: produced higher concentration in wastewater and required water to be recirculated in the system in order to create a balance in the treatment process Wastewater treatment Operators regulated the flows and added water where needed to adequately process solids Impacts to agriculture through loss of use of reclaimed water; increased pressure for supplementing with use of raw water supply (district recycles 100% of wastewater supply)

Adaptation strategies and financial impacts Undertaking study for treatment process modifications Increasing Difficulty in meeting wdr’s Increased collection system maintenance Proactive pipe patching and lining projects Installing odor control filtration Increased costs are particularly difficult for the significant disadvantaged community (dac) areas the District serves.

Water system issues Age of water concerns in tanks as a result of lower usage Disinfection by-product management challenges Higher water temperatures in tanks Bio film formation Taste and odor complaints Gambled with potable supply by trying to gauge use while maintaining lower tank storage levels to overcome problems experienced Exacerbation of water loss factor in ditches by reducing flow

end