Laserfiche WebLink
<br />. <br /> <br />(hazard) structure. This classification denotes that failure of the dam would cause <br />extensive property damage and probable loss of human life. <br /> <br />Riverside Dam and Reservoir currently is not equipped with an emergency spillway, which <br />is required by the DWR's Ru/es and Regu/ations for Dam Safety and Dam Construction. <br />Construction of a spillway on the dam will reduce the risk of dam failure by overtopping <br />during an extreme flood event, enhancing the safety of dowt)~tream residents and property. <br /> <br />. <br /> <br />AL TERNA TIVES EV ALUA TED <br />A range of structural alternatives for the spillway construction were considered, including <br />1) Don't build the project, or 2) Construct a spillway on the dam. Alternative 2 has several <br />sub-alternatives including 2a) construct a soil cement (or otherwise) lined open channel <br />spillway, 2b) construct an unlined open channel spillway with sheet piling grade/erosion <br />control cutoff walls, 2c) construct an unlined open channel spillway with a soil cement <br />grade/erosion control cutoff wall, or 2d) construct an unlined spillway without <br />grade/erosion control cutoff walls. <br /> <br />A subjective evaluation of the alternatives follows. <br />1. Don't Build the Proiect <br />No construction will be involved. <br /> <br />The DWR has issued a nominal storage restriction on Riverside Reservoir of 0.05 <br />foot. It is expected that if no action is taken, the DWR's storage restriction will be <br />progressively increased to reduce the available active storage in the reservoir in <br />order to provide protection to the downstream public. It is anticipated that the <br />storage restriction could be as great as 31 ,000 acre feet, which is about 1/2 of the <br />total usable reservoir storage volume. The impact of the usable storage reduction <br />would have profound adverse impact on the water users under the Riverside <br />irrigation system. The do nothing alternative is not feasible. <br /> <br />. <br /> <br />2. Construct a Spillwav on the Dam <br />This altern::'ive is feasible and is considered the preferred alternative. There are <br /> <br />7 <br />