Septic Engineer for Owasco, NY Lake and Upland Lots

The short answer for Owasco

Owasco is the town on the east side of Owasco Lake, and the lake is the drinking water source for both the City of Auburn and the Town of Owasco. Any new system, repair or replacement here needs a design professional, and repairs in the Owasco Lake watershed are on the short list where Cayuga County says a Licensed Professional Engineer or Registered Architect must prepare the plans, even for a modification.

Designs are prepared and stamped by a New York licensed Professional Engineer (PE). Backwell coordinates the design, the Cayuga County Health Department submittal, and the install.

Owasco Lake watershed rules, current and proposed

The watershed has had rules and regulations since 1984. An update was drafted by the Owasco Lake Watershed Management Council on behalf of the City of Auburn and the Town of Owasco, supported by both boards in October 2020, and sent to the NYS Department of Health for state review. Cayuga County posts the 2023 version with state recommendations dated September 15, 2023. As of this writing we have not seen a final adoption notice, so treat these as proposed. They are worth designing to now, because they show where review is heading:

• The absorption area, including the required expansion area, at least 100 feet from the high-water mark of Owasco Lake and from all waters of the state.
• No absorption area in a FEMA floodway, floodplain or special flood hazard area unless the bottom of the field is at least 2 feet above the flood elevation.
• An extra 50 percent of usable area set aside for future expansion.
• Land based holding tanks only during construction, or as a repair where nothing else fits, at least 50 feet from the lake or any water, with an alarm at 80 percent full and three years of pump-out receipts kept.
• All new installs and all alterations, repairs and replacements, except minor repairs, designed by a design professional.
• No new construction, addition or change of use, such as turning a garage into a bedroom, until the county has approved the septic side.
• Lakefront owners who offer short term rentals notify the watershed inspection division by May 1 each year.

Soils on the east side of the lake

The lakeshore and the low ground behind it run to wet, fine textured soils: the county soil survey maps Canandaigua silty clay loam, poorly to very poorly drained, in low lake plain positions around Owasco Lake. Climbing east onto the till, the ground turns to Honeoye silt loam on the drumlins, well drained, and Lima silt loam, moderately well drained. That split decides most designs. Upland Honeoye lots can often carry a conventional or shallow trench. Shoreline lots with water near the surface, and narrow lake lots where the field cannot reach the 100 foot line, push toward a raised system, a mound with pressure dosing, or an enhanced treatment unit ahead of the field.

Appendix 75-A sets the limits. A raised system needs at least one foot of original soil faster than 60 minutes per inch, the high groundwater at least one foot below the surface, and slopes no steeper than 15 percent. A mound needs bedrock at least two feet down, natural soil faster than 120 minutes per inch, and slopes of 12 percent or less.

How a septic design works in Owasco

1. Address and plans. Bedrooms, new house or replacement, and if you rent the place out. Estimate in 1 hour.
2. Locate the lake line and every watercourse. The 100 foot distance is measured to the absorption area and the expansion area. Tributary streams count, not just the lake.
3. Perc and deep hole. At least two perc tests and a test hole at least six feet deep. On wet ground the deep hole records the seasonal high water and the type of water table.
4. PE stamped plan. System type picked from the soil data, with the reserve area drawn.
5. Cayuga County review. Three copies, application and fee to 8 Dill Street, Auburn. County staff check the property and review against Appendix 75-A. The accepted plan is copied to the town Code Enforcement Officer.
6. Install, then certify. The PE verifies the install before backfill and files the certificate of construction. Abandoned tanks are pumped and removed or filled.

Problems we see on Owasco lots

Timeline and county paperwork

The county says approval to construct may take up to 4 to 6 weeks after a complete submittal. Before closing on any Owasco home, Cayuga County also requires the septic be inspected and the tank pumped; a transfer inspection is valid for one year and counts as the routine inspection.

Sources

• NYS DOH, 10 NYCRR Appendix 75-A, Wastewater Treatment Standards, Residential Onsite Systems
• Cayuga County Health Department, Septic System Installation and Inspection
• Cayuga County Health Department, Instructions to Obtain Septic System Plan Approval for New Construction
• Cayuga County Health Department, Application to Install a New Septic System (rev. 1/7/2025)
• Cayuga County Health Department, Application to Modify/Replace an Existing Septic System (rev. 1/7/2025)
• Cayuga County, Owasco Watershed Rules and Regulations update project
• Owasco Lake Watershed Rules and Regulations, Updates 2023 (State Recommendations dated 9/15/23)
• USDA NRCS Official Soil Series Description, Canandaigua
• USDA NRCS Official Soil Series Description, Honeoye
• USDA NRCS Official Soil Series Description, Lima

Rules and fees as published by each office on the date this page was written. They can change; the design is checked against the current versions at submittal.