Geohydrologist Greg Kamman was tasked to review the revised Alternative Project as proposed and tentatively approved in the FEIR. Additional review of the revised project including responses to the Final EIR by Analytical Environmental Science’s (AES) Report dated July 2016) resulted in additional research being conducted to verify the accuracy of the hydrologic analysis by AES.
Upon further review of July 2016 Supplemental Report submitted by AES on behalf of the Walt Ranch project, Kamman’s report of August 26, 2016 determined the following:
- The EIR fails to accurately assess the estimated water run-off rates and to quantify the long term changes in run off rates and associated erosion potential (Kamman Report, pg. 2)
- The EIR does not include any onsite field tests of ripped soil types to verify deep ripping will alter the soil, accordingly the hydraulic analysis which relies upon unverified designations in order to estimate peak storm run-off rates is invalid. (Kamman Report, pg. 3)
- The EIR does not provide storm water runoff estimates by vineyard block, and instead relies upon estimates that are calculated from much larger drainage areas and does not factor in the drainage elements concentrating and increasing peak flows from individual vineyard blocks. (Kamman Report, page 3)
- To illustrate the conclusions reached by Mr. Kamman in his August 2016 Report, Vineyard Block 21B was chosen for a hdyrologic analysis to verify conclusions set forth in the EIR. Walt’s experts state in the EIR that there is no difference in drainage created by this vineyard block, in their pre-construction vs. post-construction modeling. Kamman’s hydrologic modeling revealed that simulated project drainage improvements proposed by the project actually increased hydrological outflow (run-off) from this vineyard block by 12.4 to 15.7% higher depending on the storm intensity. (Kamman Report, pps. 3-4)
- Geohydrologist Kamman‘s August 2016 report conclusively establishes that there are serious deficiencies in the EIR and that the EIR does not accurately identify areas of increased run-off and erosion potential. He further opines that the results of his hydrologic study call into question the suitable of the EIR in identifying and evaluating the potential for adverse impacts association with project erosion control measures and structures (Kamman Report, pgs. 4-5)
- If drainage “improvements” proposed to be installed by Walt increase water outflow from one vineyard block by an average of 13.86% (where their experts said there would be no change in storm water runoff), how much additional water will be deflected from Walt downhill into the community of Circle Oaks from the development of all vineyard blocks?
- Kamman was also asked to evaluate whether the Walt Ranch project could increase potential for landslide hazards. He was asked to review this concern in light of the March 2016 failure of SR121, located a short distance south of the community of Circle Oaks. Of concern, the Walt Project experts have admitted by their own hydrologic studies, that peak storm runoff will be greater than pre-project conditions in 41 of 69 project vineyard blocks.
Note: Kamman’s August 2016 report establishes that the results of the AES Hydrologic Study are inaccurate; therefore the peak storm runoff rates will be much greater than predicted by the Walt Project. ( Kamman Report, p. 5)
- Of further concern is that at least 7 vineyard blocks have been designed where their drainage pours directly onto existing mapped landslides where the ground is already known to be unstable. (Kamman Report, p. 5)
- Kamman’s concluding remarks in the category of Project Effects on Landslide Potential is particularly chilling. Kamman opines that given the steep slopes and propensity for landslides to occur during large storm events, there is a potential to impact infrastructure downstream of these slides including but not limited to the Circle Oaks development, their utility delivery system, as well as Highway 121. (Kamman Report, pgs. 6-7).
Note: For further reference to storm water run-off and failure of Highway 121 see also Living Rivers Council Appeal letter, Exhibit 3, dated 08-29-2016: Cal Trans Traffic Advisory-Closure of SR 121 re: emergency road closure, 3-18-2016.
Update: Stream Flow and Sediment Yield Monitoring
- Geohydrologist Greg Kamman’s August 2016 Report is critical of the Water Quality Monitoring Program reached following negotiations between the City of Napa and the County of Napa post Walt Ranch ECPA and FEIR approval. The approval of the Erosion Control Plan and FEIR did not include any provisions for monitoring of stream flow and sediment from Milliken Creek flowing through Walt Ranch and into the City of Napa’s Milliken Reservoir. Faced with either working out a deal with the County or filing an Appeal of the Walt Ranch approval, the City of Napa and the County of Napa hastily resolved their concerns which was memorialized in a Memorandum dated August 15, 2016.
See Exhibit 4 to the Living Rivers Council Appeal Letter, dated 08-29-2016, which is the City of Napa Memo re: Update to Conditions of Approval of Water Quality Monitoring Program re: Walt Ranch Vineyard Conversion Project, 08-15-2016.
- Kamman has consistently opined that the Walt Ranch project will result in sediment-laden runoff water which will eventually end up in creeks, such as Capell Creek and Milliken Creek, endangering species of fish and amphibians (See Kamman Report, Section regarding biological impacts.)
- In Kamman’s August 2016 Report, he states that the water quality monitoring agreement falls short of properly monitoring concerns and results in only a “snapshot” of concentrations at a single point in time. The current water quality monitoring program does not accurately: Quantify the changes in the volume of total sediment derived from the project site; quantify measurements of suspended turbidity and bedload sediment concentrations; nor does it include continuous streamflow monitoring which is required to quantify sediment yields. (Kamman Report, pg. 7)
Exhibit 4: Living Rivers Council Appeal Letter 08-29-2016; City of Napa memo re: Update to Conditions of Approval of Water Quality Monitoring Program re: Walt Ranch Vineyard Conversion Project, 08-15-2016