CITY COUNCIL INFORMATIONAL MEMORANDUM
Meeting: November 7, 2023
To: Cupertino City Council
From: Matt Morley, Assistant City Manager
Re: Cupertino Sanitary District Update
The Cupertino Sanitary District is an independent district that is governed by an elected Board of Directors. The District provides sanitary sewer services throughout Cupertino and portions of neighboring jurisdictions and works closely with the City on various projects that the District is responsible for performing, including development projects, capital improvements, and maintenance. The District sets its own policy direction.
Much of the information provided in this report is available on the District’s webpage:
https://www.cupertinosanitarydistrict.org/home
Wolfe Road Sewer Relocation Project
In preparation for the replacement of the Wolfe Road overpass, the District is relocating the sanitary sewer line that crosses Caltrans right of way at that location. This project is underway and the District anticipates completion in late 2023. Traffic will be impacted as lanes are closed during the course of construction.
Infiltration and Inflow Reduction
The District reports that “45-50 percent of peak flows in the sewer system during wet weather flow” originates from the infiltration of stormwater or groundwater into the system. This results in stormwater mixing with and being treated as sewage as opposed to flowing directly into the creek or stormwater system. The District has implemented a program to reduce the occurrence of this infiltration. The program includes finding and fixing sources of infiltration and modeling peak flows to identify the impact of infiltration on system capacity. By managing infiltration and inflow, the District can make more capacity available for development projects.
Ordinance 130 – Property Line Cleanouts
In March, the District Board approved Ordinance 130 governing the placement and maintenance of sanitary sewer line cleanouts. The ordinance is intended to provide the District greater access to service the sanitary line. The ordinance includes an increased cost share with property owners when new cleanouts are required.
Sewer Service Rates
In May of this year, the District Board set rates for sanitary sewer service, including a 5% residential rate increase. The base rate for a single-family connection is $734.56 per year. The District sets rates through a public hearing and publishes the rates on their website. These charges for service are billed and collected on the property tax bill for each property.
System Capacity and Anticipated Upgrades
The District has historically had concerns with system capacity, with physical limitations on the flow capacity constrained by system size as it flows through the City of Santa Clara. Through past hydrology analysis, capacity concerns arose during wet weather conditions largely due to infiltration issues. Infiltration occurs where stormwater enters the sanitary sewer system, an undesirable condition in any case. Stormwater should stay in its own separate system. The District has seen increases in flow during wet weather, which points directly to stormwater infiltration. As a result, the District has invested purposefully in infiltration testing and reduction strategies.
Most recently, the District re-evaluated the hydrological model assumptions and made changes that more accurately reflect existing conditions. The calculations from these changes demonstrated a system with less capacity constraints, leaving the District in a place where it can accommodate foreseeable new development.
Other system upgrades have been focused on renewal and resiliency of aging infrastructure, including sewer lines and pump stations. As pump stations are modernized, the District will include opportunities to provide permanent back up power where it does not currently exist and will upgrade digital monitoring and control systems to allow for more responsive and reliable operations. These upgraded pump stations are also expected to reduce episodic odor issues.
Sustainability Impact
There is no sustainability impact resulting from the recommended action in this report.
Fiscal Impact
There is no fiscal impact from the recommended actions in this report.
California Environmental Quality Act (CEQA)
Not applicable.
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Prepared by: Matt Morley, Assistant City Manager
Approved for Submission by: Pamela Wu, City Manager