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CITY OF SANTA ANA Well No. 32 Nitrate Mitigation and Rehabilitation Study 3. PROJECT ALTERNATIVES The alternatives consist of a variety of several options that include the following: 1. No action 2. Blending in the distribution system at the following locations: • Garthe Reservoir • Memory Lane Pressure Reducing Facility (blending Well No. 32 water into the well water from the City's easterly sources) 3. Utilizing treatment technologies to reduce the nitrate levels located either on -site at Morrison Park or at Garthe Reservoir 3.1 No Action A no action scenario would result in the City operating Well No. 32 as it had in the past. The well would be started and pumped to waste until the nitrate level dropped to acceptable levels before allowing the groundwater to enter the distribution system. The pump to waste time varied based on the concentration of nitrate detected. The City has reported that the pumping time varied as much as 6 to 18 hours. The City would then be discharging anywhere between 900,000 to 2,700,000 gallons of groundwater to waste. Well No. 32 waste flows are piped from the well and discharged to Santiago Creek, located adjacent to Garthe Reservoir. The City must coordinate with Riverview Golf Course located downstream as the City discharges into Serrano Creek which merges downstream with the Santa Ana River. Riverview Golf Course lies within the Santa Ana River and course operations are impacted due to the well discharge. Therefore, the City's operation of Well No. 32 would remain constrained both by the nitrate level in the groundwater and the impacts to the golf course. 3.2 Blending in the Distribution System High - nitrate groundwater is largely managed by blending the groundwater with water from other sources that has lower nitrate concentrations. This approach is common for drinking water treatment in larger municipalities and obviously requires a second, low- nitrate water source. 3.2.1 Blending in Garthe Reservoir The City prepared a nitrate blending and monitoring plan in 2010 for both Garthe and Walnut Reservoirs. One of the potential alternatives is to blend water from Well No. 32 into Garthe Reservoir. The blending plan was reviewed to determine whether it would be feasible to blend Well No. 32 water into the reservoir. Garthe Reservoir site consists of three reservoirs with a total of 16 million gallon storage capacity, Wells 18, 24, 36, and 39 and six booster pumps. The City provides an ongoing nitrate blending treatment process in which high nitrate water from Well No. 18 and Well No. 24 are blended with low nitrate water from Well Nos. 36 and 39. The wells are staged in the SCADA system to utilize the low nitrate wells first (i.e., Well Nos. 36 and 39) followed by the high nitrate wells. The staging of the wells is based on the reservoir level. The control logic in the station's Remote Terminal Unit is programmed to prevent Well 18 and Well 24 from coming on alone (i.e., Well Nos. 36 or 39 have to be running first). Table 3 -1 P:V' 00597 \008ylrngineoing\OS\_We11J2- Nitrate - Mitigation \Dian Report \02text dot 51 .13 3 TETRA TECH