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CITY OF SANTA ANA Well No. 32 Nitrate M i t I g a ti on and Rehabilitation Study Bristol Street: • Six lanes (three lanes in each direction, with a raised median in some portions) with heavy traffic with a combination of commuter, local resident, and school traffic Phased construction across the signalized intersection at Bristol Street and Memory Lane • Santiago Creek crossing — there is a bridge there the pipe will either need to be bored and jacked under the creek or hung from the bridge • Bristol is congested with existing utilities: — Sewer — Water — Underground dry utilities (gas, electric, telephone, cable) — Storm Drain • Provisions for maintaining access to a church on west side of street need to be provided • No residences fronting street • Commercial area at the intersection of Bristol and Memory Lane Memory Lane: Four lanes (two lanes in each direction) Existing utilities consist of: — Existing sewer and water within the street — Overhead utilities • Residential area but no residences front street Westwood Avenue: • Two travel lanes, one in each direction • Overhead utilities • Provisions for maintaining access to a church and a public park need to be provided The size of the pipeline is dependent on how the Garthe reservoirs are used for blending. There are two options. The first is to send flows during start-up to Garthe Reservoir until the half the MCL goal is achieved and then divert the flow back into the distribution system. The second is to send all flows to Garthe Reservoir and then use the pump station at Garthe Reservoir to pump back into the system. The City has stated that the area of the distribution system Well No. 32 discharges into historically experiences low service pressures when the well is not operating. Operating the well into the system improves the service pressure delivered to the City's customers. The City would prefer to keep the well connected to the distribution system within Westwood Avenue. However, Well No. 18, located at the Garthe Reservoir site is in decline. Well No. 18 was drilled in 1956 and production has lessened over time with the City estimating that the well probably only has about 10 years of useful life remaining. Upon the loss of Well No. 18, the City could replace the ground water flows that went into Garthe Reservoir with the ground water pumped from Well No. 32. Summarized below are the design issues that will need to be considered for each alternative: Alternative 1— Utilize Garthe for Blending Only There is a hydraulic grade difference of 140 feet between the distribution system (272 feet) and the Garthe Reservoir high water level (132 feet). This impacts the operation of the well pump. 2. Well pump horsepower of 300 hp with a design flow rate of 2,500 gpm. PMOOS9T00WEngineering \OS_ _Well -32- Nitrate- MitigationOmfl Report \02text`25 1 _275 TETRA TECH