City of Gonzales
PUBLIC WORKS / CITY ENGINEER DEPARTMENT
STAFF REPORT
TO: Honorable Mayor Rios and City Council
DATE: February 20, 2024
FROM: Patrick Dobbins, Public Works Director/City Engineer THROUGH: Carmen Gil, City Manager
SUBJECT: Update on the Wastewater Treatment Plant Emergency Repairs
RECOMMENDATION
It is recommended that the City Council receive this progress report on the Emergency Repairs at the City’s Wastewater Treatment Plant.
BACKGROUND
The WWTP has been located on City-owned parcels just east of the Salinas River since the 1950’s. It’s been expanded periodically over the years with the current configuration constructed in 1982. The Salinas River flooded the WWTP during the 1995 floods, and one of the disposal fields was flooded in April 2011. Both times, the City repaired the storm damage.
The City’s Wastewater Treatment Plant (WWTP) is comprised of the following elements:
• Headworks where wastewater enters the facility via a 21-inch sewer main that conveys the wastewater from Gonzales residents, businesses, and industrial facilities. The sewage passes through a bar screen to catch items that are larger than one inch. • A Lift Station that pumps the sewage from the headworks to the ponds to begin the treatment process.
• Eight ponds separated into two trains where wastewater is treated through the introduction of air and detention time. Typically, wastewater moves through four ponds over a 60-day period before it’s released to percolate in the disposal fields.
AGENDA
ITEM
18 • Treated wastewater from Ponds 7 and 8 is then discharged into three separate disposal fields to percolate into the ground. The disposal fields are designated A, B and C and each have an area of seven acres. Public Works staff rotates which field the treated wastewater is drained into. The disposal fields are drained and regularly disced using a tractor with long ripper teeth to break any crust that might slow percolation.
In mid-January, City Public Works staff observed that the percolation of treated wastewater in the three disposal fields had slowed. The on-site groundwater monitoring wells indicate a higher water table because of last winter and this winter’s rainfall. The heavy rainfall over the several weeks exacerbated the situation due to additional water entering the wastewater system from inflow and infiltration.
Groundwater (infiltration) seeps into sewer pipes through holes, cracks, joint failures, and faulty connections. Stormwater (inflow) flows into sewers via roof drain downspouts, storm drain crossconnections, and through holes in manhole covers.
Based on staff’s recommendation, the City Council authorized spending $250,000 to perform emergency work at the wastewater treatment plant at the February 5, 2024 meeting by Resolution No. 2024-03.
REVIEW & ANALYSIS
The work over the last week at the WWTP disposal fields has included:
• Engaged Swift Tectonics to regrade the levees for Disposal Fields A, B and C. After visiting the WWTP last Tuesday, they moved in equipment and began grading work on Friday, February 9th.
They worked Saturday, February 10th and continued this last week. • Rain 4 Rent installed pipe and a pump to convey treated wastewater to the Emergency Overflow Basin on Friday, February 9th.
• Polaris Consulting (Contract City Surveyor) performed a topographic survey of the disposal fields to determine the design elevations for the levees to guide Swift Tectonics grading work. • Staff installed a pump at Disposal Field B to pump water from Field B to Field C. • Public Works staff cleared vegetation the levees in preparation for the work by Swift Tectonics. • City staff has also cleared vegetation from the ponds in the treatment plant. • Staff disced and ripped the emergency basin before discharging into it via the Rain 4 Rent pipeline. • Staff was at the WWTP last Saturday and Sunday to monitor the grading work and to start and stop the pumps to the emergency pond and Field B.
• Staff continue to keep the pumps running by filling with diesel fuel and moving pumps as needed.
Staff informed Regional Board staff of the emergency work prior to engaging the contractors and performing any field work.
Staff will provide additional information on the emergency work including incurred costs as part of our presentation at the Council meeting.
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 emergency work supports our Vision by making improvements to the wastewater treatment plant’s ability to safely contain and treat sewage.
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 ensure 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 X Yes No N/A
• Housing X Yes No N/A
• Recreation X Yes No N/A
• Environment X Yes No N/A
• Education X Yes No N/A
Explain: See Vision above.
ALTERNATIVES
There are no alternatives to performing this emergency work.
BUDGET IMPACT
At the February 5, 2024 City Council meeting, staff was authorized to spend up to $250,000 on Emergency repairs at the wastewater treatment plant. This project is funded with Sewer Impact funds.
CONCLUSION
It is recommended that the City Council receive this progress report on the Emergency Repairs at the City’s Wastewater Treatment Plant.