Sewer System Management Plan – Update
Sanitary Sewer Overflow (SSO) Information
When SSO’s, or sanitary sewer overflows occur, the City of Mt. Shasta follows its Sanitary Sewer Overflow Emergency Response Plan, or SSOERP. This plan is a required element in the overall Sewer System Management Plan and is included as Appendix E in that plan. The SSOERP outlines the procedures that are followed in the event of an SSO from the initial response, to cleanup and sampling efforts, to final analysis and corrective action to prevent future overflows.
To assist in evaluating SSO’s on a risk basis to determine appropriate and possible mitigation levels with respect to closure, cleanup, and sampling, the City will evaluate all SSO’s according to the following factors as to the level of risk and exposure to the public as well as appropriate clean up measures:
- SSO impact to the public: Heavy foot/vehicular traffic, highly public, around congregations of people, possibly during outdoor events.
- SSO volume: Larger volume SSO’s will require more extensive cleanup measures. Smaller volumes will be generally easy to clean up.
- SSO Location/destination: Is SSO contained to small area, easy to capture? Enters storm drain or drainage feature? Confined to dirt or paved area? Enters major body of water (i.e. Cold Creek)
- SSO ability to clean up: Does nature of containment provide easy clean up or does the SSO enter storm drain and is gone? Or does the SSO require significant cleanup efforts.
- Other environmental factors: Is the SSO occurring during a storm event with much rainfall and dilution?
- High Risk: Immediate and Significant risk to the public or environment.
If the SSO is in a highly public area with heavy foot/vehicular traffic, City crews will take necessary steps to prevent public access (barricades & signage), remove all raw sewage and materials, clean up and disinfect the affected area prior to permitting re-entry. Consists of high volume SSO’s, especially those greater than 50,000 gallons and discharge to a surface water. Eliminating the SSO will also be a top priority in the initial response. Higher risk SSO’s that are difficult to capture, contain, or clean up may require upstream and downstream sampling for Coliform bacteria and ammonia.
- Medium Risk: Some risk to the public or environment, considered less than significant with some mitigation efforts.
Some capture, cleanup, and disinfection is possible. Lower impact to the public. Smaller volumes that are easier to manage. Sampling may be necessary depending on effectiveness of mitigations.
- Low Risk: No immediate or significant risk to the Public or environment.
Little to no impacts to the public. SSO volume is low and enters storm drain with high flows which carries the diluted SSO away quickly and prevents any real cleanup or sampling efforts. No public impact, short duration. Cleanup efforts are easy and highly effective or otherwise not necessary or possible. Sampling not required.
If you see water coming out of a manhole, please notify the City immediately.
To report Sanitary Sewer Overflows (SSO’s):
During City Hall business hours (9:00 am-3:00 pm) call (530) 926-7510
After hours call: (530) 926-7540
To view the State Water Resources Control Board CIWQS SSO Public Reporting Page for Sanitary Sewer Overflows (SSO’s) go to: https://www.waterboards.ca.gov/water_issues/programs/ciwqs/publicreports.html#sso