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8.4.2 Reservoir Alternative 2 - SO Acre-Ft Reservoir with Clay Liner <br />Alternative 2 is for the construction of a new 50 acre-ft reservoir near the end of the Ogilvy Ditch <br />system. The new reservoir will use the existing ditch outlet that was installed on the ditch to feed the <br />small detention reservoir built by the OLIC. The side slopes for the new reservoir will be set at <br />3H:1 V for the upstream and downstream slopes. A geotechnical investigation of the reservoir site <br />found the site soils to be granular and fairly permeable; due to the granular nature of the soils the <br />reservoir will require an impermeable liner. For alternative 2 the reservoir liner was assumed to be a <br />compacted clay liner. The compacted clay liner has the benefit of requiring less maintenance than a <br />HDPE liner, the clay liner also is less susceptible to damage due to gas buildup, and the clay liner <br />also provides more protection to damage done by a high ground water table. However, the <br />compacted clay liner is not resistant to wave/wind erosion and will thus require erosion protection. <br />The estimated total project cost for this alternative is $ 885,000 as show in Table 6. A complete <br />breakdown of the work proposed and expected costs are included in Table 6. <br />8.4.3 Reservoir Alternative 3 - SO Acre-Ft Reservoir with HDPE Embankments and Clay Liner <br />Base <br />Alternative 3 is for the construction of a new 50 acre-ft reservoir near the end of the Ogilvy Ditch <br />system. The new reservoir will use the existing ditch outlet that was installed on the ditch to feed the <br />small detention reservoir built by the OLIO. The side slopes for the new reservoir will be set at <br />3H:1 V for the upstream and downstream slopes. A geotechnical investigation of the reservoir site <br />found the site soils to be granular and fairly permeable; due to the granular nature of the soils the <br />reservoir will require an impermeable liner. For alternative 3 the reservoir liner was assumed to be a <br />combination of a HDPE liner along the embankments and a compacted clay liner along the base, the <br />HDPE liner on the embankments has the benefit of being both resistant to UV desiccation and <br />suitable for protection against wind/wave erosion while the clay liner along the base will allow for <br />the protection of the liner against a buildup of gas pressure beneath the reservoir. <br />The estimated total project cost for this alternative is $ 536,000 as show in Table 7. A complete <br />breakdown of the work proposed and expected costs are included in Table 7. <br />8.4.4 Reservoir Alternative 4 -100 Acre-Ft Reservoir with HDPE Liner <br />Alternative 4 is for the construction of a new 100 acre-ft reservoir near the end of the Ogilvy Ditch <br />system. The new reservoir will require a new diversion from the existing ditch. The side slopes for <br />Feasibility Study of the Ogilvy Augmentation Comparry Page 10 <br />Well Augmentation Project <br />