October 2009 - South Tahoe Public Utility District
October 2009 - South Tahoe Public Utility District
October 2009 - South Tahoe Public Utility District
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Like Project No. 14 (page 11-81), project implementation for Project No. 15 is contingent upon<br />
water quality and quantity in the Indian Creek Reservoir.<br />
The Upper Dressler Ditch carries freshwater from Snowshoe Thompson No. 1 Ditch at Indian<br />
Creek to Indian Creek Reservoir. Portions of the ditch are concrete lined, while other sections<br />
consist of loosely consolidated earth. These earthen areas are prone to a high rate of leakage<br />
and erosion. Lining or piping sections of this ditch can reduce sediment transport. This project<br />
should be phased on a priority reach basis. The <strong>District</strong> completed in 2007 the conversion of<br />
approximately 2,000 feet to piped conveyance. Problem sections are planned to be improved<br />
first and the concrete sections may require replacement as they deteriorate in the future.<br />
11.2.1 Project Description<br />
Unlined sections of the Upper Dressler Ditch are planned to be piped in a 48” diameter pipeline<br />
to promote conveyance and ditch stability. The general construction method for piping the<br />
Upper Dressler ditch will be to place the pipeline in the existing ditch alignment and backfill and<br />
compact.<br />
Figure 11.1 (at the end of Section 11) depicts the reach of the Upper Dressler Ditch that has a<br />
high seepage rate and should be the priority reach when this project is implemented.<br />
11.2.2 Project Considerations<br />
The sections in most need of repair are entirely within <strong>District</strong> owned lands; access exists along<br />
the entire alignment. Other than the pipe material, suitable bedding and backfill material may be<br />
the greatest construction cost.<br />
A detailed condition assessment for the portions of the C-Line to be converted to freshwater<br />
conveyance which is associated with Project No. 2 (page 9-63) is necessary before final<br />
decisions are made regarding the Upper Dressler Ditch Conveyance Improvements.<br />
The conceptual cost of the Upper Dressler Ditch Conveyance Improvements project is $2.5<br />
million.<br />
11.3 Project No. 16 - Indian Creek Treatment Wetlands<br />
This project addresses the purpose and need statement:<br />
<br />
PN-9. Ability to meet Indian Creek Reservoir water quality requirements is impaired and<br />
the <strong>District</strong> needs to meet TMDL requirements for the Indian Creek Reservoir.<br />
Project No. 16 is contingent upon the success of the <strong>District</strong>‟s current Hypolimnetic Oxygenation<br />
System project. The TMDL on Indian Creek Reservoir sets a water quality standard for<br />
phosphorus. Concerns exist that flushing more water through the reservoir will transfer the<br />
elevated level of phosphorus to downstream systems, thereby impeding the water quality<br />
objectives of the receiving water bodies. If the Hypolimnetic Oxygenation System project meets<br />
TMDL goals the need for the Indian Creek Treatment Wetlands Project will be eliminated. If the<br />
Hypolimnetic Oxygenation System project does not meet TMDL goals, then the <strong>District</strong> may be<br />
faced with increasing flushing flows through the Indian Creek Reservoir. Project No. 16 could<br />
be constructed as shown in Figure 11.2 (at the end of Section 11) to address the impacts of<br />
increased flushing flows on downstream systems.<br />
<strong>South</strong> <strong>Tahoe</strong> <strong>Public</strong> <strong>Utility</strong> <strong>District</strong><br />
Recycled Water Facilities Master Plan - <strong>October</strong> <strong>2009</strong> Page 11-83