City of Gonzales
PUBLIC WORKS / CITY ENGINEER DEPARTMENT
STAFF REPORT
TO: Honorable Mayor Rios and City Council
DATE: January 13, 2025
FROM: Patrick Dobbins, Public Works Director/City Engineer THROUGH: Carmen Gil, City Manager
SUBJECT: Update on the Wastewater Treatment Plant Emergency - New Disposal Pond
RECOMMENDATION
Staff recommends the City Council Receive a Progress Report on the recent Emergency Work performed at the City Wastewater Treatment Plant.
BACKGROUND
The City operates a wastewater system that serves residents, businesses, and industrial facilities. The Municipal Wastewater Treatment Plant (MWWTP) is permitted to treat and dispose of 1.3 million gallons/day by the Central Coast Regional Water Quality Control Board under Waste Discharge Requirements R3-2006-005. During October and November, Public Works staff observed that the MWWTP treatment ponds were fuller than usual and was challenging to discharge treated wastewater using the three disposal fields.
At the December 11, 2024 Special City Council Meeting, staff reported the MWWTP was struggling to dispose of wastewater for the following reasons:
1. The last two years of heavy rainfall and regular dam releases from Lake Nacimiento and Lake San Antonio has resulted in higher groundwater along the Salinas River. Groundwater used to be more than 10 feet below the bottom of the disposal beds and it’s now closer to 4 feet. Higher groundwater has decreased the performance of the disposal beds as there’s less storage for the water to drain to.
2. The slow percolation of the disposal beds has made it difficult for Public Works staff to get a tractor with implements in the disposal beds to rip the bottom of the beds to improve the percolation.
AGENDA
ITEM
16 3. The processing facilities ramped up their production for the holiday season and some of the processing facilities exceeded their Industrial Wastewater (IW) allocations in the last two months.
Without adequate percolation, the infiltration ponds are filling and operating at minimum freeboard, risking breech of the basins and an uncontrolled wastewater spill. Additionally at a certain freeboard, the flow hydraulically backs up in the treatment ponds, impacting the overall treatment process. Disposal of treated wastewater is critical to operating the MWWTP.
Dudek Consulting prepared the construction drawing for the new disposal bed on city-owned property just east of the MWWTP. Adding this disposal bed improves the MWWTP ability to dispose of treated wastewater. The new disposal bed will be used in future Phase 2 of the IWTF with some modifications.
Staff discussed the construction of the new disposal bed with Regional Water Board staff, and they support the approach as long as it doesn’t increase the capacity of the MWWTP and is only used in emergencies. They will revise the City’s WDR permit to incorporate the use of the new disposal pond with conditions.
At the December 11, 2024 Special Meeting, the Council authorized staff to proceed with emergency work at the MWWTP to construct the new disposal bed. Polaris Consulting performed the construction staking based on Dudek’s design. Swift Tectonics was engaged to construct the new disposal bed and mobilized immediately after the Council’s authorization. The new disposal bed was completed on December 24, 2024 and City staff immediately began pumping treated wastewater to the disposal bed.
REVIEW AND ANALYSIS
The estimated and updated costs for the emergency work are in this table:
Contractor/Consultant
Estimated Costs
as presented at
Dec 11, 2024
Council meeting
Costs as
of 1/07/2025
1 Swift Tectonics to construct Disposal Bed and
install piping $400,000 $309,607
2 Trucking Wastewater to City of Soledad Sewer
System $200,000 $50,000
3 Dudek Consulting (design services) $10,000 $12,145
4 MNS Engineers (construction inspection) $10,000 $5,112 5 Polaris Consulting (construction staking) $10,000 $3,500 6 Pacific Crest (soil compaction testing) $20,000 $4,620 7 Pump Procurement and Installation $115,000 Pending Quotes 8 Fencing Material and Installation $25,000 $5,000
9 Misc Piping for Pump Suction & Connection $10,000 $0
10 Contingency $150,000 $0
Total = $950,000 $389,984
As of January 6, 2025, the new disposal bed is percolating well and the freeboard in the MWWTP ponds has increased significantly. City staff will continue to use the new disposal bed allowing the existing MWWTP disposal fields to be sequentially dried out and ripped by Swift Tectonics in the coming weeks, thereby returning them to previous functionality.
How Recommendation Supports the Vision
Gonzales will continue to be a safe, clean, family-friendly community, diverse in its heritage, and committed to working collaboratively to preserve and retain its small town charm.
Explain: This project supports our vision by making improvements to the wastewater system to for better operation.
Explain how the Recommendation Directly Implements the Mission The City Council and Staff of the City of Gonzales will realize our Vision by providing the leadership, commitment and resources necessary to provide excellent services that enhance the quality of life of our diverse community. X Yes ____ No____ N/A
Explain: Maintaining and improving the wastewater treatment plant enhances the community’s quality of life by providing for treatment and safe disposal of the City’s wastewater.
City services will be delivered in a cost-effective, respectful and friendly manner to insure the safety and well being of the residents and the promotion of business, recreational, housing and employment opportunities in an environmentally sustainable manner. X Yes ____No ____ N/A Explain: See Vision explanation above.
Strong fiscal policies allow us to provide appropriate infrastructure for:
• Public Safety Yes X No N/A
• Housing X Yes No N/A
• Recreation Yes X No N/A
• Environment X Yes No N/A
• Education Yes X No N/A
Explain: See Vision above.
ALTERNATIVES
This is a progress report on the recent emergency work at the Municipal Wastewater Treatment Plant, so there isn’t an alternative to consider.
BUDGET IMPACT
This work will be funded with wastewater CIP fund by slightly deferring projects. A revised CIP budget will be presented at the next council meeting.
CONCLUSION
Staff recommends the City Council Receive a Progress Report on the recent Emergency Work performed at the City Wastewater Treatment Plant.
Attachments:
• Project Photos