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<br />MEMO-Linda <br />March 21, 1980 <br />Page -2- <br />6) In view of the unstable and porous nature of the strata beneath <br />the dam, and as Fox and Associates recommend the same, please clear <br />the revised dam design with them. <br />7) Please confirm that all culverts passing beneath roads(with <br />the exception of the existing PVC C') will be corrugated metal. <br />8) On page 86 of Design of Small Dams, the text states "The <br />inflow design flood most critic- a~ . should be used for final <br />design. Often it is necessary. to route floods from both <br />thunderstorm rainfall and general storm rainfall to determine which <br />flood type is critical." As thunderstorm rainfall will yield a <br />higher cfs in this watershed, it should be routed. <br />9) In sizing ditches, using a peak runoff/acre figure derived <br />from total peak flow divided by total area assumes uniform slope, <br />land conditions, and other factors, so disturbed and undisturbed <br />areas should be computed separately, or the SCS or rational formula <br />used. <br />Comments on Surface Water Monitoring: <br />1. Please clarify that any discharge from the mine area will be <br />monitored per the NPDES standards. <br />2. The irrigation water flowing over the property from the north, <br />if sufficient to cause discharge of itself (keeping storage volume <br />for the 10 yr. event open in the pond), should be monitored above <br />and below the mine disturbance. Applicant should suggest a schedule <br />and parameters, probably including those critical to agriculture <br />(Boron, Chlorine, Selenium, Sodium Absorption Ratio). <br />