Iowa Hill update

Michael Raffety

Aug. 25, 2014

The Sacramento Municipal Utility District  has contracted with Jacob Associates to do core drilling, underground design and “rock engineering” for the district’s Iowa Hill pumped storage project, according to SMUD’s summer report, the “Confluence.”

The data collection was completed in May and the contractor “found rock at the planned location of the powerhouse to be suitably strong and said groundwater leakage from rock fractures appears manageable.”

Jacobs also found suitable rock conditions for pressurized water tunnels and shafts, minimizing the need for tunnel lining. That will save money on the project, which is currently estimated to cost $800 million.

SMUD appears to be carefully inching toward its pumped storage project. This fall the district will drill and blast a 1,600-foot deep exploratory 10-by-10-foot tunnel. “More core drilling will be conducted at the end of that tunnel to learn more about the geology around the planned location for the powerhouse cavern,” the newsletter stated.

The Iowa Hill pumped storage project would pump water up from Slab Creek Reservoir at night when power is cheap and then release through the new powerhouse during the day when power-on-demand is needed to run air conditioners in Sacramento.

The pumped storage and its powerhouse in a cavern would generate 400 megawatts, according to SMUD’s Website. That compares to the 688 megawatts SMUD’s entire “Stairway of Power” produces from its 11 reservoirs and eight powerhouses on the upper American River watershed.

On July 24, 2014, SMUD announced it received a 50-year license renewal for its 65-year-old Upper American River Project. The license is issued by the Federal Energy Regulatory Commission.

“The new license also directs SMUD to move forward with the design and potential construction of the proposed Iowa Hill pumped-storage development. This development, which circulates water between a lower and upper reservoir, would add a significant level of operating flexibility that would help SMUD balance supply and demand on the grid. It would play a crucial role in allowing SMUD to develop larger supplies of intermittent wind and solar power. As directed in the new license, SMUD will continue to evaluate the feasibility of building the development over the next three years, before the SMUD Board of Directors determines whether to proceed with construction,” the press release stated.

Similar to requirements FERC placed on the El Dorado Irrigation District, FERC is requiring SMUD to commit to “a 20-year program to upgrade all existing UARP recreation facilities, including campgrounds, picnic areas, paved bike trails, hiking trails and shower facilities at a ski chalet.” Additionally, SMUD is required to release water to sustain the rafting industry in El Dorado County.

The tunnel boring is scheduled to continue through May 2015. Final design and permitting will occupy SMUD from this fall through 2018. Actual powerhouse construction isn’t slated until 2019, with site clearing and transmission line construction projected for the fall of 2017.

Actual operation isn’t expected until 2023, according to SMUD’s schedule.

SMUD is also cooperating with the El Dorado County Water Agency, which is seeking water rights from the SMUD project. UARP is strictly a power project and not a potable water storage project.

“More than 50 years ago we agreed to allow El Dorado County to divert up to 40,000 acre-feet of water from our UARP facilities. In 2005 we went further and agreed to store water for El Dorado County, which would enhance the reliability of the community’s water supply, especially during drought years. We stand ready to make good on our commitments as soon as the county obtains consumptive water rights from the state,” SMUD said in its newsletter.

SMUD nearly filled its reservoirs this winter (2013-14) despite the severely diminished snow and rainfall. The advantage of obtaining 40,000 acre-feet of potable water rights to the Upper American River Project plus a 15,000-acre drought reservation is that it would save the $100 million cost of building a reservoir of that size, “If such a large reservoir could even be built in today’s regulatory environment.”


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