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This is a partial list of FAQs we’ve received about the McKinley Water Vault. We will continue to update these as the project continues.

Why is the Vault necessary in East Sacramento?
East Sacramento is at the top end of the combined sewer system that flows to the Sacramento Regional Wastewater Treatment Plant. When the combined sewer system is at maximum capacity, flooding and outflows occur in East Sacramento from local runoff and sewage. The McKinley Water Vault will reduce flooding and outflows by temporarily storing the wastewater. The size of the Vault has not been determined yet, but it will likely be in the range of 5-7.5 million gallons.

What will the McKinley Water Vault store?
The Vault will reduce the amount of wastewater (storm water runoff and sewage) that floods the streets in the combined sewer system by temporarily storing it during large storm events. The Vault is kept empty except during large storm events and is drained within one to three days after the storm.

What is the combined sewer system?
The combined sewer system collects and carries wastewater (sewage) and storm water runoff through a single pipe network for treatment at the Sacramento Regional Wastewater Treatment Plant and the City’s wet weather treatment facilities during significant storm events. 

The system serves over 200,000 City residents including people in the downtown, East Sacramento, Land Park, Curtis Park and Oak Park neighborhoods. San Francisco and Sacramento are the only cities in California that have combined systems. The City is managing the system and increasing the capacity to protect the community from street and structure flooding. 

What is the benefit of a combined sewer system? 
The combined sewer system provides water quality benefits by providing tertiary or primary treatment to the combined storm water runoff and wastewater prior to being released into the rivers. 

Why is McKinley Park the preferred project location? Why not McKinley Village?
Utilities identified the need for underground storage to reduce street flooding and outflows in the McKinley Park and East Sacramento neighborhood. The initial concept included a deep tunnel under Alhambra Blvd. with a large diameter pipe and additional underground storage in the McKinley Village development. This concept was further evaluated in the 2015 Combined Sewer System Improvement Plan (CSSIP) Update. Utilities studied four other possible locations in East Sacramento as part of the 2015 CSSIP but none worked nearly as well as McKinley Park. 

How does groundwater affect the project cost?
The groundwater table rises as it nears the river.  Higher groundwater tables require a more extensive design and construction process which drives up costs. We are trying to avoid digging in water saturated soils as much as possible to reduce the project cost. 

Will Utilities cut down trees to create space for the Vault?
The pre-design surveys and layout analyses underway as part of the pre-design phase will help answer this question. Utilities will make every reasonable effort to minimize and/or eliminate the need for tree removal.

What are the solutions to address and mitigate potential odor issues?
The Vault will have a below-ground odor control facility that will filter the air from the Vault. It will not vent to open air but will filter the air through a filter system. The City is successfully operating three similar underground storage facilities without creating order issues 

Why is the project paid for by rate payer dollars, not by the developer and industry contributing to the problem? 
Flooding in East Sacramento is an existing problem that was identified long ago. Developers are required to mitigate their impact to the system.

What above ground structures do you anticipate? 

We anticipate a bathroom facility that will blend in with the look of the park and hold the electrical facility. Any installed above ground structures will not distract from the park’s aesthetics. We will work with the community on this aspect as it progresses. 
What park areas will construction affect? What will it look like when you’re done?
Although design is only conceptual at this time, we anticipate constructing the Vault beneath the baseball field along 33rd Street between the picnic and rose garden areas. We know construction will cause disruption in the park, to the neighbors, rose garden events and community. We will work to mitigate these impacts as much as possible. After construction has been completed, we will reconstruct the baseball field, plant new sod and install new irrigation. 

How will construction affect parking and neighborhood traffic?

Utilities will examine and determine potential impacts during pre-design analyses, which is starting now. We will have a public outreach program to alert neighbors and businesses before and during construction.

Have a question or comment? Email us at or call (916) 808-5545.