25I - AGMT - OCWD ASSESSMENT - Laserfiche WebLink

Home Browse Search

CITY OF SANTA ANA Well No. 22 Nitrate Mitigation and Re h a b l i la ti 0-n Study presents the average nitrate levels and flow rates for the wells. Well No. 32 data was based on historical records and the desire of the City to pump at 2,500 gpm. Table 3 -1. Well Nitrate Levels Table 3 -2 presents the worst case scenario of pumping various combinations of wells into Garthe Reservoir and the anticipated nitrate levels. The predicted nitrate levels were calculated from the mass balance of well flow rates and nitrate levels in accordance with the City's 2010 nitrate blending plan. Flow from Well No. 32 was then added to each of the pumping scenarios to determine the impact on the reservoir nitrate level. As indicated below, the addition of Well No. 32 to each of the blending scenarios would increase the total combined nitrate levels in Garthe Reservoir anywhere from 1.6 mg/L to 4.8 mg/L. Although the combined nitrate levels in the reservoir would increase, they would still meet the City's goal of achieving less than half the MCL. The 2010 blending plan indicates that the actual 3 -year average nitrate level was about 11 mg/L, which was less than most of the operating scenarios in the blending plan. If Well No. 32 flows were to be included, it would probably increase the actual level anywhere from 2 to 5 mg/L. Table 3 -2. Garthe Reservoir - Worst Case Scenario Pumping Combinations In order to convey the flows to Garthe Reservoir, approximately 3,250 feet of new pipeline would need to be constructed as shown on Figure 1. From Well No. 32 the new pipeline would head southerly in Westwood Avenue then west in Memory Lane and then turn south on Bristol Street terminating at Garthe Reservoir. Summarized below are design issues that would need to be addressed in regards to this alignment selection: PAP00599 \0086\Hngm ,1ng \05\ We11-32- Nitrate- Mitlgatlon\Deaft Report\02textdoax - 6 - TETRA TECH 251 -24