Ripley Seeks USDA Review of Cost/Seismic Safety Design Policies for Los Osos Project


In a detailed letter/report to the USDA, 30-year water/wastewater professional Dana Ripley calls on the federal agency to review San Luis Obispo County’s campaign of “misrepresentations” and “omissions” on STEP versus gravity collection systems, and utilize new data from recent earthquakes and severe liquefaction in Japan and New Zealand that should immediately change the course of the waylaid Los Osos Wastewater Project.



As the debate rages in Washington over deep cuts in federal programs, Dana Ripley has a good idea how the federal government can curb wasteful spending and instantly save ratepayers at least $50 million in the disadvantaged Central Coast community of Los Osos — scrap San Luis Obispo County’s costly and dangerous $200-million, gravity-collection city-sewer system, scheduled to break ground outside town next year, and adopt a safer, lower-cost alternative while there’s still time.

“Since this project represents the largest public works project in the history of San Luis Obispo County, and represents the single largest USDA loan by RUS (Rural Utilities Services), I believe that the increased scrutiny here is justified,” Ripley wrote in a June 29 letter to Jonathan Adelstein, Administrator, Rural Utilities Services, U.S. Department of Agriculture, in Washington.

The USDA is lending the County $86 million towards construction of the gravity collection system segment of the sewer, backed by $25,000 liens on 5,000 homes in Los Osos’ “Prohibition Zone” to pay for the $200 million project. Ripley wants the USDA to review project details in the loan approval, particularly what he calls “misrepresentations” and “omissions” in the County’s EIR, and for the USDA to consider new information from the recent Japan and New Zealand earthquakes relevant to Los Osos’ high-risk liquefaction zone.

“It is abundantly clear that the liquefaction potential is a well-documented, high-risk geologic hazard in Los Osos as confirmed by the applicant’s (San Luis Obispo County) consistent liquefaction mapping and declaration in the 2008 project environmental report that the liquefaction impact is ‘considerable and, therefore significant.’

Ripley wants the USDA to take advantage of the three-year, $17 million 3-D earthquake impact modeling study now required prior to the Nuclear Regulatory Commission’s relicensing of the Diablo Canyon plant, which is within eight miles of Los Osos’ liquefaction zone. Ripley is not seeking a delay in the project timeline, although he emphasizes that it is imperative to act now to address liquefaction to protect life and property, utility and sewer lines, and the drinkable water supply, should the sewer break apart.

“While I do not suggest here that the Los Osos sewer project should be delayed until completion of the Diablo Canyon 3-D seismic study, I do suggest that known seismic hazards need an increased level of scrutiny and attention given to what has recently transpired in Japan and New Zealand,” he writes. “This new information would be relevant to the Los Osos wastewater project in addition to the Diablo Canyon nuclear plant…”

The seismic hazards at Diablo Canyon have drawn the cameras and the attention of bandwagoning County and State politicians, while the seismic hazards of building a gravity sewer in a high-risk liquefaction zone almost next door has drawn only silence. “For the residents of Los Osos,” wrote Ripley, “the risk of severe liquefaction is likely substantially greater than risk of radiation exposure from Diablo Canyon, even though the community is within eight miles of the nuclear facility.

“This study will assess safeguards necessary to protect public health and safety in the event of a severe seismic event anywhere along the central California coastline… and will likely provide new information added to the existing body of knowledge related to seismic hazards along the California central coast as well as seismic hazards specifically within the Los Osos Valley.”

Ripley is the author of the 2006 “Ripley Plan” for wastewater collection, treatment and water re-use for Los Osos, and a consultant to STEP system builder W.M. Lyles Co., rejected as a bidder by the County in 2009 just prior to the promised design-build cost-competition Lyles undoubtedly would have won, much to the embarrassment of the County and its significantly more expensive predetermined gravity technology, and favored builder, Broomfield, Colo.-based MWH Americas.

New Information

Ripley believes the County has erred by deferring disclosure of liquefaction mitigation measures until after the current redesign by Cambridge, Mass.-headquartered CDM. Important new information in the form of research, reports, images and video of Christchurch, New Zealand’s extensive liquefaction damage to sewer lines, is readily available on the web. “Thousands of Christchurch homes do not have operable sewers and must resort to use of chemical toilets for the foreseeable future,” wrote Ripley.

“Information was provided on the relative performance of PVC and HDPE pipe systems in severe liquefaction events (in Christchurch). The difference between ‘likely thousand of breaks and lesser flaws’ [in PVC pipes] versus ‘not a single instance of damage’ [in HDPE pipes] is largely attributable to the differing material properties of PVC pipe and HDPE pipe… Due to the flexibility of HDPE pipe material, HDPE is inappropriate for gravity collection systems where constant pipe slopes and invert elevations are critical to performance.

“As confirmed by the Christchurch experience, the use of pressure HDPE pipe would fully mitigate the liquefaction risk for the Los Osos sewer collection system,” he wrote. “The additional costs for this mitigation would be zero according to the PER (preliminary environmental report), since costs between the PVC and HDPE alternatives are essentially the same.

“‘The Ripley Plan,’ which includes HDPE pressure collection as a fundamental component represents a cost savings of at least $50 million — on-lot costs included — relative to the gravity system proposed by the applicant…,” he wrote. “The cost savings would be substantially greater if the applicant’s proposed gravity system incorporates ‘hard-fix’ mitigation measures to reduce the liquefaction hazard risks.

“A shutdown of the Los Osos sewer system caused by liquefaction would mean either evacuation or chemical toilets for much of the community very similar to what has transpired this year in Christchurch.”

“The decision here is whether to mitigate or not mitigate the liquefaction hazard,” Ripley told The Rock. “There is no middle ground on whether to mitigate or to not mitigate; I see it as ‘black and white’ since there are no shades of gray on this… The proposed soft fixes are not mitigation of any substance, so hard fixes are the only real means to mitigate. Hard fixes for the gravity collection might include various soil modification schemes for 45 miles of pipeline and 800 manholes which would be cost-prohibitive and likely not perform well anyway in a significant liquefaction event.

“Liquefaction impacts from New Zealand and Japan have jolted geotechnical professionals worldwide, and seismic and liquefaction standards need a re-look for all construction projects moving forward. Add to this fact that the applicant’s liquefaction mitigation measures are limited to soft fixes, which on a $200 million project should be unacceptable knowing what geotechnical and engineering professionals know today since the 2011 quakes.

“The ob
vious solution is to put in a system that can withstand the ground movement and uplift conditions to be expected in liquefiable soils in areas of high seismic activity.”

Click here to read Ripley’s complete letter to the USDA.

Related links:
Ripley Letter to USDA 6-29-11
Christchurch Wastewater System Status 5-26-11
“Blakeslee’s Seismic Contradiction” (The Razor)
“The Liquefaction of Los Osos” (The Rock)