Design Level Geotechnical Investigations for the Pacheco Reservoir Expansion Project Notice of Preparation of a Draft Environmental Impact Report

Joint letter logos

Sierra Club Comments
October 30, 2024
Via email to: Todd Sexauer, Senior Environmental Planner [tsexauer@valleywater.org]

The Sierra Club appreciates the opportunity to provide scoping comments in response to the Notice of Preparation of a Draft Environmental Impact Report for Design Level Geotechnical Investigations for the Pacheco Reservoir Expansion Project. Our comments are detailed below. These comments reference the Design Level Geotechnical Investigations for the Pacheco Reservoir Expansion Project Draft - Initial Study and Mitigated Negative Declaration (MND), published in June 2024.

  1. Comments on Project Description
     
    1. Provide sufficient information to understand impacts of access routes. The project description should include a section about the access routes shown in yellow on Figures 2.2a through 2.2e (pages 2-5 through 2-9 of MND). Additional information is needed so the public can evaluate impacts on plants and wildlife, soil, water quality (erosion), etc. The information should include a table describing each access segment that includes the following: length of the segment; quality and width of current surface (or indicate off-road); maximum slope; stream-bed crossings; vegetation types (including any natural communities); BMPs to be applied; and “other potential concerns.” Accumulated impacts from all the segments should also be evaluated in the appropriate environmental impact categories.
    2. Discuss impact of Surface Geophysical Surveys on vegetation. Electrical Resistivity Imaging will extend for 1,520 feet, more than 1⁄4 mile (page 2-4 of MND). Seismic-refraction lines total approximately 16,890 feet, about 3.2 miles (page 2-12 of MND). Laying down multiple cables will require several workers to move back and forth along the line and will disturb existing vegetation. If there are any sensitive plants, they could easily be trampled. Under Biological Resources, please discuss how disturbed vegetation and creation of an ad hoc temporary trail will impact vegetation and how possible impacts to special status plants will be mitigated.
    3. For exploratory borings (page 2-17 through 2-34 of MND) more details are needed to explain how disposal of drilling fluids will be handled. Please provide information about where drilling fluids will be stored on site and where drilling waste will be taken to be disposed of.
    4. Please expand on the information provided under 2.3.5 Project Schedule, Table 2-4 Proposed Project Equipment and Duration of Use Equipment (Page 2-37 of MND), listing equipment to be used for the geotechnical investigations. Other equipment needed to implement BMPs and mitigation measures is not included in the list of equipment to be used for the project. Specifically, many water trucks will take multiple trips daily to implement dust control measures and tire washing and to water exposed, dry stockpiles. Power vacuum street sweepers will be used to remove dirt from public roads. Many hazardous materials trucks will be used for delivery and disposal of hazardous materials and hazardous waste. Table 2-4 should include these and any other equipment (such as tremie pipes) used to support this project or to mitigate the impacts of the project. And the impacts of this additional equipment should be included in the analysis of emissions (air quality), transportation, water supply, etc.
    5. MND Section 2.3.5 Project Schedule says “Valley Water would review weather conditions, weather forecasting, biological observations, and site conditions to determine when geotechnical field work on site would be allowed to occur” (page 2-37 of MND). Please document specific metrics and trigger values to instruct decisions about commencing or halting work on the project site.
       
  2. Comments on Environmental Evaluation
    ​​​​​​​
    1. Section 4.9 Hazards and Hazardous Materials should include a discussion on hazards to the workers who will be implementing the Project, under Worker Safety Requirements (page 4-121 of MND). Specifically, the MND needs to address hazards related to extreme heat or related to smoke from nearby wildfire. Please document mitigation measures to protect workers from heat, and from wildfire smoke. This may not be required by CEQA analysis but needs to be addressed.
    2. Section 4.10 Hydrology and Water Quality discusses operation of the existing Pacheco Reservoir and North Fork Dam (page 4-128 of MND), but neglects to include information about the restricted operation criteria put in place by the Division of Safety of Dams due to spillway deficiencies. Please include information about operation restrictions in place for the existing Pacheco Reservoir.
    3. Section 4.19.3b related to Water Supply (page 4-230 of MND) discusses the use of water “for the purposes of dust control on roadways and staging areas, for exploratory drilling, and for in situ jet testing.” Please quantify the amount of water to be used for each purpose. Will all this water really come from one hydrant at Casa de Fruta? How many truck trips of what size per day? How often will dust control water trucks need to be refilled?
    4. Section 4.20.3 Discussion of wildfire impacts CEQA Checklist item b relates to exacerbating wildfire risks (page 4-242 of MND). During high fire danger warnings, vehicles operating on dry grass can spark a dangerous wildfire. A mitigation measure should be included to cease operations on days designated as high wildfire danger. This is especially crucial since there will be minimal clearing around each worksite, and some access routes will be off-road. Operations will therefore be conducted on or very near dry grass. Most concerning are the hammering operations for the Surface Geophysical Surveys which do not involve any vegetation removal; this hammering could cause sparks and increase wildfire danger. Please describe how hammer sparks will be mitigated to reduce the potential for wildfire.