Wastewater
In November 2024, after receiving a generous $40,000 grant from the Rose Foundation, Cabrillo Estates Property Owners Association engaged MNS Engineering to estimate the cost of connecting Cabrillo Estates to the Los Osos Wastewater System. MNS is a well-established organization that provides quality infrastructure consulting services to the wastewater resources, transportation, and government service markets throughout California. MNS has considerable experience in the wastewater and water resources industry, and the organization has an extensive resume of completed wastewater and water projects. The report was completed in April 2025.
On May 1, 2025, CEPOA held an informational meeting to share the report as well as additional information about the costs of installing onsite wastewater treatment systems. A narrated recap of the meeting is available, as well as a download of the slides. If, after reading the report and viewing the slides, you have remaining questions, please see the Q&A page.
Background
In 2020, the County of San Luis Obispo adopted new, much more stringent requirements for new and replacement onsite water treatment systems (OWTS). These requirements are contained in the Local Agency Management Plan (LAMP) which now regulates the use of septic systems in the county, including in Cabrillo Estates.
In 2020, the County of San Luis Obispo adopted new, much more stringent requirements for new and replacement onsite water treatment systems (OWTS). These requirements are contained in the Local Agency Management Plan (LAMP) which now regulates the use of septic systems in the county, including in Cabrillo Estates.
The Cabrillo Estates Property Owners Association (CEPOA) formed a small, ad hoc committee to learn more about the LAMP, OWTS, and the alternative of connecting Cabrillo Estates to the Los Osos Wastewater System (a.k.a. "the sewer"). That led to a general meeting of property owners on May 14, 2024. The purpose of that meeting was to make sure property owners were aware of the LAMP and its requirements, and to judge interest in connecting to the sewer.
At the meeting's conclusion, attendees were asked to complete an informal poll to determine interest in pursuing the possibility of connecting to the sewer. Here is a graph of the results:
In November 2024, with funds provided by a grant from the Rose Foundation, CEPOA contracted with MNS Engineering, Inc., to conduct a study of the feasibility and cost to connect the properties in Cabrillo Estates to the Los Osos Wastewater System. Local contractor Sam Crizer volunteered his time to study four sample properties in Cabrillo and estimate the cost for each to install an onsite wastewater treatment system of the type now required should the existing septic system fail. Results of both studies are to be presented at a special meeting on May 1, 2025.
Additional background resources
- FAQs: Local Agency Management Program for Onsite Wastewater Treatment Systems
- FAQ for Cabrillo Estates. This "draft" document was prepared by San Luis Obispo County prior to the May 14, 2024 general meeting.
- Nitrate Fact Sheet. Basic information from the California Department of Public Health
- California Septic Tank Requirements. From a seller of underground septic tanks, this gives a good rundown of what's involved in the installation of a new system with the exception of the fact it refers to a traditional septic tank-leach field arrangement. What must be added in Cabrillo Estates is the advanced treatment system. Here is a sample owners manual from one vendor.
- Onsite Wastewater Treatment System Services. You'll find links to the LAMP and information on Septic System Operation and Maintenance
- Los Osos Groundwater Conditions Update. This Central Coast Regional Water Quality Control Board staff report from September 2022 provides a brief update on groundwater conditions in the Los Osos Groundwater Basin.
- State Water Resources Control Board. Here you'll find the California Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Treatment Systems (OWTS).
- Central Coast Regional Water Quality Control Board
- Los Osos Valley Groundwater Basin. You'll find background information as well as a link to the Los Osos Basin Management Committee.
- Additional documents provided by the Central Coast Regional Water Quality Control Board
Below is a recording of the informational meeting held July 25, 2023. The presenter is Michael Sundberg of MicroSepTec, a manufacturer of an advanced onsite wastewater treatment system. We are just beginning to gather information about what is involved in replacing our septic tanks with the county-required systems.
It is important to note there are many more costs involved than Mr. Sundberg mentioned in this recording. His company only manufactures the unit. Each installation is a custom project which would involve permits, design engineering, preparing the location, installing the system and constructing the leach field. After that any cleanup and restoration of driveways, patios and landscape would be an additional cost. Mr. Sundberg cannot estimate these costs for us. It is also important to note that a system will be sized according to the number of bedrooms in a house. Then adjustments may need to be made if there are more or less people using the system.
It's complicated! It is a mini-wastewater system. There are ongoing testing requirements. The systems require maintenance, including some parts that have to be replaced every 5-10 years.
A question we did not think to ask Mr. Sundberg: What happens if a house remains vacant for a period of time. Several of our Cabrillo property owners are part-time residents.
It is important to note there are many more costs involved than Mr. Sundberg mentioned in this recording. His company only manufactures the unit. Each installation is a custom project which would involve permits, design engineering, preparing the location, installing the system and constructing the leach field. After that any cleanup and restoration of driveways, patios and landscape would be an additional cost. Mr. Sundberg cannot estimate these costs for us. It is also important to note that a system will be sized according to the number of bedrooms in a house. Then adjustments may need to be made if there are more or less people using the system.
It's complicated! It is a mini-wastewater system. There are ongoing testing requirements. The systems require maintenance, including some parts that have to be replaced every 5-10 years.
A question we did not think to ask Mr. Sundberg: What happens if a house remains vacant for a period of time. Several of our Cabrillo property owners are part-time residents.