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Stevens Reservoir Completion 'Touch and Go' for 2008 |
Sheila Berger | 10/8/08
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With a long dry autumn, the Steven’s Reservoir dam and expansion project could still be completed this year — but an unusually wet summer has Pagosa Area Water and Sanitation District officials holding their breath.
According to PAWSD Project Manager Gregg Mayo, “It’s touch and go. With another period of rain like we saw last weekend, we probably won’t make it.”
The project, which began with land acquisition twenty years ago, raises the existing dam ten feet. This will result in a storage capacity nearly triple that of the old reservoir. Continued...
Pouring the spillway |
Completion of the dam this year would mean that with average winter and spring precipitation, the reservoir could be refilled by mid-2009. A full reservoir would facilitate a PAWSD Board decision to lift the moratorium on new District inclusions. The moratorium has been in place for nearly all of the last decade due to lack of raw water supply. Delay in project completion could mean that the reservoir may not be filled until next autumn or spring of 2010.
 The dam at Steven’s is an earthen-fill, as opposed to a concrete, dam. When building an earthen-fill dam, soil moisture content is everything. The State of Colorado requires an optimum moisture content (percent moisture) in the soil after compaction, with an allowance of one percent lower to two percent higher. For the Steven’s project, the acceptable range is approximately 14 percent to 17 percent. Western Technologies, Inc. is the on-site geotechnical firm that tests the soil. These reports must be furnished to the State. The operators turn the soil in the borrow pit until it reaches the optimum moisture content, and then deliver it to the dam site where it is spread and compacted in 6 inch lifts, and tested again. If at any point the soil fails the test – and relative humidity in the air is part of the soil moisture equation – the soil must be scarified and turned until it dries. Continued...
Working the dirt that will become the dam in the borrow pit |
An abundance of summer, and now fall, rain has wreaked havoc on the construction schedule. Approximately 60 work days have been lost due to weather. As the days get cooler and shorter, it becomes more and more difficult to work the moisture out of the soil.
Once frost sets in, it will require at least an hour of work in the morning to remove the frost protection (approximately two feet of dirt to cap what has already been compacted and tested) and another two hours in the evening to replace the frost protection. Although extra crews and equipment have been brought in, and work weeks have been extended to seven days, the project may not be completed in 2008. At a certain point the cost-benefit ratio of continuing work in cold, wet weather is too high.
Meanwhile, PAWSD staffers continue to hold their breath and hope for a few more weeks of dry weather.
You can visit the PAWSD website for more information and a Virtual Tour of the Steven’s Project. On November 17 at 8:00am, tune in to KWUF 1400 AM when PAWSD staff will discuss the Steven’s Reservoir Project. |
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