Report Shows Gila Diversion At Risk for Fatal Flaws
Silver City, NM – The Gila Conservation Coalition sent a letter on Monday to Interstate Stream Commission (ISC) chairman, Jim Dunlap, outlining how commissioners were misled by staff about conclusions of an independent engineering review by RJH Consultants (RJH) of the Gila River diversion Preliminary Engineering Report (PER) prepared by Bohannan Huston (BHI). The conclusions were contradicted by the FY15 Gila Diversion work plan prepared by staff and approved by ISC Commissioners at their meeting in June. The work plan claimed that RJH confirmed that the BHI study was “adequate for conceptual level project planning,” but RJH found that “several project components were not adequately addressed in the PER and it is currently unknown if these components represent significant technical challenges or potential fatal flaws….for storage reservoirs and dams, project water availability, and Gila River sediment.” There are currently no plans approved by the ISC to evaluate issues identified by RJH as high priority and critical to determining if the Gila River diversion project is fatally flawed from a technical or financial perspective. Though over $1 million was approved by the ISC for the first half of FY2015, it is unclear what the ISC will do with this funding and if answers to key questions raised by RJH will be addressed.
“The feedback provided by RJH Consultants corroborates the technical input provided to the Commission by former ISC director Norm Gaume. Ignoring the recommendations of the professional engineers at RJH is irresponsible and unprofessional and could result in millions of dollars in wasted Arizona Water Settlements Act (AWSA) funding on a Gila River diversion project that is fatally flawed,” stated Allyson Siwik, Executive Director of the Gila Conservation Coalition.
In testimony and a report presented to the ISC at its monthly meeting in Tucumcari on April 30, former ISC director Norm Gaume told commissioners that the Gila River diversion proposal currently under consideration “would produce little or no water but with major waste of money, time and effort.” Gaume’s analysis of the BHI PER concludes that the average net yield of the Gila River diversion project will be much less than half of the 14,000 acre-foot per year junior water right; the safe yield (minimum annual yield) will be very small or perhaps zero; the project will be hugely expensive to build; operations will be inordinately costly due to energy and exchange costs alone; and existing water rates for project beneficiaries would more than double and $100’s of millions of state funding would be required for construction.
In its engineering review, RJH identifies a number of potential fatal project flaws from either a technical or financial standpoint that were not adequately addressed in the BHI PER, including the following:
- No Quantification of Seepage Losses – “The expected seepage losses, when combined with the evaporative losses could easily equal or exceed the planned minimum annual diversion yield of 10,000 acre-feet, which would result in no available usable water from the project.” The Phase II BHI work plan and FY2015 work plan do not include a task to estimate seepage losses of the Gila River diversion project.
- Lack of Concept Plans for Storage Reservoir Dams – RJH recommends that “typical concept plans and sections for the Alternate 2B dams be developed including developing appropriate quantities required to construct zoned earthfill dams, which were not included in the conceptual-level cost estimate.” Because this could be such a significant cost, RJH identifies this task as a top priority as it could make the project infeasible. The Phase II BHI work plan and FY2015 work plan do not include tasks to address this key element.
- Project Water Availability and Yield Not Assessed – RJH states that the annual diversion yield is needed in order to correctly size reservoirs and conveyance facilities and determine amount of water the diversion could produce reliably. The PER also did not quantify projected annual net yield that is, according to RJH, “the foundation for justifying the project. When estimating the net project yield, Gila River historical flow and diversion records, past and projected future hydrologic cycles of drought and higher than average precipitation should be compared to computed system losses to evaluate long-term project viability.” This fundamental task is not included in either the BHI Phase II work plan or in the FY2015 work plan.
- Project Cost Estimates for Dams “Substantially Understated” RJH identified 12 missing major elements required to safely design and construct zoned embankment dams. RJH’s opinion is that “the total cost for the project may be significantly low. There is considerable uncertainty in many geological and design concepts for the dam and some of the required elements of the dams were not included. In additional some of the unit costs are unrealistically low. When all of these elements are considered, it is our opinion that the cost of the dams could be underestimated by more than 100 percent. Therefore it is our opinion that the overall project costs may be 25 – 50 percent higher than the current estimate.” It is unclear from the BHI Phase II work plan if RJH’s recommendations to revise the conceptual level cost estimate for the project will be implemented.
- Sediment Control Was Not Addressed RJH states that “sedimentation could have a significant impact on design, sizing, and feasibility of the diversion, conveyance and storage reservoirs….. ….This potentially important issue does not appear to have been addressed. Depending on the results of this evaluation, this could become a significant project feasibility issue.” It is unclear from review of the BHI Phase II work plan and FY2015 work plan if sedimentation will be adequately addressed.
“The ISC must conduct additional work to determine if the Gila River diversion is fatally flawed. By ignoring its own independent engineering review, the ISC risks millions of dollars in AWSA funding and taxpayer dollars to continue to pursue a project that is potentially technically and financially infeasible,” explained Siwik.
The letter from the Gila Conservation Coalition to Jim Dunlap, chairman of the Interstate Stream Commission, is available at https://www.gilaconservation.org/wp/wp-content/uploads/2014/06/LetterISC-RJHReview.pdf