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1 DER <br /> 12 . <br /> 12 . Based on the limited investigation and monitoring data obtained , it is <br /> unknown if the shallow perched water is continuous between MW-2 and MW- <br /> 5. Based on the limited investigation and monitoring data obtained , it is <br /> unknown why the concentrations increased in the upslope well (MW-2) while <br /> the concentration decreased in MW-5 (downgradient well ) between the March <br /> 1998 and present. Especially since Norman's Nursery began irrigating on <br /> April 20 , 1998 and has irrigated all but three days since May 16 , 1998 . It is <br /> unknown what the source of the perched water and nitrate-nitrogen is, that <br /> existed upslope of the nursery. Natural recharge, springs, vernal pools and <br /> the cattle grazing may be the explanations . Furthermore , the cause of the <br /> decrease and/or dilution of the nitrate-nitrogen in the groundwater near MW-5 <br /> are also unknown . <br /> 13. Total annual precipitation near the site has recently been [as high as] i <br /> approximately 35 inches. <br /> 14 . During three of the four quarterly monitoring events conducted to date , the <br /> concentrations of nitrate-nitrogen in all of the sample locations were <br /> consistent. In fact, the concentrations of nitrate-nitrogen upstream of the <br /> nursery's basin were frequently greater than the water within the basin (or its <br /> discharge, as applicable) . The only exception was at the beginning of the <br /> irrigation season (Third Quarter 1998) prior to the nursery's reinstitution of <br /> treatment of their tailwater with KI-Nitrifier. <br /> 15. Kleinfelder recommends that the groundwater monitoring be continued . <br /> 16 . Since surface water quality does not appear to be impacted significantly by <br /> Norman's Nursery's activities throughout the year (4 quarters) of monitoring <br /> that has taken place at the subject site, Kleinfelder recommends a decrease <br /> in the frequency of monitoring . Therefore, on behalf of Hakeem , Ellis & <br /> Simonelli and Norman's Nursery Kleinfelder recommends that the Monitoring <br /> & Reporting Program No. 97-811 be revised in the following manor: <br /> Norman's Nursery should continue to treat the tailwater within Basin B <br /> using KI-Nitrifier (or comparable treatment alternative) <br /> daily surface water flow monitoring and observation should continue <br /> weekly surface water sampling and analysis should be reduced in <br /> frequency to monthly <br /> monthly surface water sampling and analysis should include all <br /> surface water sampling points detailed in M&RP No . 97-811 <br /> additional surface water sampling for analysis should be conducted <br /> within 2 to 8 hours of the opening of the culverts and the release of <br /> any water to Potter Creek <br /> 17. Based on the laboratory reports for the surface water samples obtained , it <br /> appears that additional sources of nitrate-nitrogen exist upstream of Sample <br /> Location SIA. Kleinfelder recommends that the RWQCB review other <br /> potential sources of nitrates-nitrogen in the surface and groundwater within <br /> the area. <br /> 117226 .E02/ST013R0176 Page 10 of 40 January 31 , 2013 <br /> Copyright 2013 Kleinfelder <br />