Title
1. Consider Finding that:
a. Emergency repairs are necessary to maintain service essential to the public health, safety or welfare at the Nacimiento Dam spillway plunge pool pursuant CEQA Guideline 15269(b); and
b. Specific actions are necessary to prevent or mitigate an emergency at the Nacimiento Dam spillway plunge pool pursuant CEQA Guideline 15269(c).
2. Approving an Agreement with Whitaker Construction Group, Inc. for an amount not to exceed $2,000,000, for emergency repair and protection of the Nacimiento Dam spillway plunge pool banks; and
3. Authorizing the Interim General Manager to execute the Agreement with Whitaker Construction Group, Inc., upon County Counsel review and approval of the Agreement; and
4. Authorizing the Interim General Manager to execute Change Orders to the Agreement totaling up to $1,000,000.
Report
RECOMMENDATION:
It is recommended that the Monterey County Water Resources Agency Board of Directors:
1. Find that:
a. Emergency repairs are necessary to maintain service essential to the public health, safety or welfare at the Nacimiento Dam spillway plunge pool pursuant CEQA Guideline 15269(b); and
b. Specific actions are necessary to prevent or mitigate an emergency at the Nacimiento Dam spillway plunge pool pursuant CEQA Guideline 15269(c).
2. Approve an Agreement with Whitaker Construction Group, Inc. for an amount not to exceed $2,000,000, for emergency repair and protection of the Nacimiento Dam spillway plunge pool banks; and
3. Authorize the Interim General Manager to execute the Agreement with Whitaker Construction Group, Inc., upon County Counsel review and approval of the Agreement; and
4. Authorize the Interim General Manager to execute Change Orders to the Agreement totaling up to $1,000,000.
SUMMARY/DISCUSSION:
Storm events during January 2023 resulted in the rapid filling of Nacimiento Reservoir requiring spillway discharges up to approximately 3,000 cubic feet per second causing new erosion along the left plunge pool bank. With the potential for additional large storm events this winter, further spillway discharges could further erode plunge pool banks, including potential erosion towards the left side of the spillway along the highly erodible Monterey Formation bank material. If left bank erosion of the Monterey Formation encroaches upon the spillway, impacts could create spillway instability and a dam safety concern. Rock protection along the left bank is needed to stabilize the area and prevent erosion towards the spillway, and towards an existing PG&E power pole located on the left bank in the near term from additional storm inflow that could occur this winter. Rock protection in two unprotected areas on the right bank would also stabilize the right bank slopes in the near term from erosion towards the toe of Nacimiento Dam.
The California Environmental Quality Act (CEQA) Guidelines Section 15269 (b) and (c) exempt projects that consist of:
(b) Emergency repairs to publicly or privately owned service facilities necessary to maintain service essential to the public health, safety or welfare. Emergency repairs include those that require a reasonable amount of planning to address an anticipated emergency.
(c) Specific actions necessary to prevent or mitigate an emergency. This does not include long-term projects undertaken for the purpose of preventing or mitigating a situation that has a low probability of occurrence in the short-term, but this exclusion does not apply (i) if the anticipated period of time to conduct an environmental review of such a long-term project would create a risk to public health, safety or welfare, or (ii) if activities (such as fire or catastrophic risk mitigation or modifications to improve facility integrity) are proposed for existing facilities in response to an emergency at a similar existing facility.
Proceeding with emergency repair and protective measures for the Nacimiento Dam Spillway plunge pool left and right banks will provide near term protection from erosion encroachment upon the spillway and dam toe, preventing a possible emergency and maintaining essential spillway and dam functions.
Upon approval of these actions, receipt of necessary permits, and confirmation of Federal Emergency Management Agency (FEMA) reimbursement of expenses and construction contracting requirements, Whitaker Construction Group, Inc., of Paso Robles, California, will provide and place rock slope protection on the Nacimiento Dam spillway plunge pool left and right banks to an elevation of 618 feet to protect against erosion from spillway discharge estimated up to approximately 8,000 cubic feet per second, the highest historical spillway discharge.
OTHER AGENCY INVOLVEMENT:
FEMA (reimbursement and contracting requirements); U.S. Army Corps of Engineers (Regional General Permit 5 for Repair and Protection Activities in Emergency Situations); Regional Water Quality Control Board (Emergency Project Application).
FINANCING:
On January 31, 2023, the Monterey County Board of Supervisors approved a short-term cash advance of $7 million for storm related expenses and repairs. Reimbursement of Agency expenses is being pursued from FEMA. Coordination with FEMA is ongoing as of this writing, and further details regarding FEMA reimbursement will be presented at the Board meeting.
Prepared by: Chris Moss, Senior Water Resources Engineer, (831) 755-4860
Approved by: _________________________________________________
Lew Bauman, Interim General Manager, (831) 755-4860
Attachments:
1. Board Order