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Below is the evaluation summary for the 4343 Mortensen Road, Manteca Irrigation Well (APN <br /> 24120004)-well permit application. <br /> The evaluation, with assumptions as noted, indicates that the proposed Irrigation well is located in an <br /> area of low domestic/residential well density (1 well per section), but is not likely to interfere <br /> significantly with existing off-site wells, create unreasonable groundwater level declines/reductions in <br /> aquifer storage or to create issues with infrastructure due to subsidence and it can be approved pending <br /> any other issues that you might have with the application. <br /> Summary: <br /> - Extraction rate—600 GPM with anticipated pumping schedule 756,000 Gal/day or 2.08 GPM <br /> - Proposed new well is in an area of low domestic/residential well density (14 well per section). At <br /> least one domestic well is located approximately 1,100 feet South of the proposed Ag well <br /> - Based on the extraction rate of 600 GPM, The Theis drawdown chart predicts less than 5 feet of <br /> drawdown if the well is more than 110 feet away. <br /> - Online databases do not specify any irrigation wells located within 2,000 feet of the proposed well <br /> location. Review of aerial imagery indicates an irrigation well is present approximately 2200 feet <br /> West. <br /> - This well is proposed to replace the existing irrigation well for the 51.67-acre Almond orchard. <br /> - The applicant proposes: well depth of 550 feet, a well grout seal of 200 feet, and a maximum <br /> pumping rate of 600 GPM. <br /> - Groundwater levels estimated by DWR well data range between 62.9 (3/2/1960)to 99.4 <br /> (10/20/1970) feet below ground surface over the past fifty years.Water levels fluctuate <br /> approximately 7 to 16 feet between seasonal high and low levels. <br /> - The permit application proposes a minimum well casing/grout seal of 200 feet and appears to <br /> target the Riverbank aquifer with water-bearing zones anticipated to be under unconfined to <br /> locally confined conditions. <br /> - The annual total extracted volume is estimated to be approximately 40.079 million gallons, a <br /> peak pumping rate of 600 GPM, and an annualized/seasonal pumping rate of approximately 133 <br /> (R2) GPM. <br /> - The aquifer volume below the 51.67-acre parcel contains an estimated 3,348 acre-feet of water <br /> storage.The proposed extraction volume of 123 acre-feet per year is approximately 3.7%of the <br /> estimated aquifer storage beneath the parcel without regard to recharge each season and is <br /> considered sustainable. <br /> - The proposed well is not located within the extents of the Corcoran Clay, subsurface water- <br /> bearing sediments are semi-consolidated to consolidated, and the proposed well is not located <br /> in an area where subsidence is currently indicated,therefore subsidence is unlikely to be of <br /> significance or to create issues. <br /> r <br /> Steven Shih, REHS <br /> Program Coordinator <br /> San Joaquin County <br /> Environmental Health Department <br />